SAM D20 - Complete

Atmel SAM D20J / SAM D20G / SAM D20E
SMART ARM-Based Microcontroller
DATASHEET
Description
The Atmel® | SMART™ SAM D20 is a series of low-power microcontrollers using the 32-bit
ARM® Cortex®-M0+ processor, and ranging from 32- to 64-pins with up to 256KB Flash and
32KB of SRAM. The SAM D20 devices operate at a maximum frequency of 48MHz and
reach 2.14 Coremark/MHz. They are designed for simple and intuitive migration with
identical peripheral modules, hex compatible code, identical linear address map and pin
compatible migration paths between all devices in the product series. All devices include
intelligent and flexible peripherals, Atmel Event System for inter-peripheral signaling, and
support for capacitive touch button, slider and wheel user interfaces.
The Atmel | SMART SAM D20 devices provide the following features: In-system
programmable Flash, eight-channel Event System, programmable interrupt controller, up to
52 programmable I/O pins, 32-bit real-time clock and calendar, up to eight 16-bit
Timer/Counters (TC). The timer/counters can be configured to perform frequency and
waveform generation, program execution timing or input capture with time and frequency
measurement of digital signals. The TCs can operate in 8- or 16-bit mode, or be cascaded
to form a 32-bit TC. The series provide up to six Serial Communication Modules (SERCOM)
that each can be configured to act as an USART, UART, SPI and I2C up to 400kHz; up to
twenty-channel 350ksps 12-bit ADC with programmable gain and optional oversampling
and decimation supporting up to 16-bit resolution, one 10-bit 350ksps DAC, two analog
comparators with window mode, Peripheral Touch Controller supporting up to 256 buttons,
sliders, wheels, and proximity sensing; programmable Watchdog Timer, brown-out detector
and power-on reset, and two-pin Serial Wire Debug (SWD) program and debug interface.
All devices have accurate and low-power external and internal oscillators. All oscillators can
be used as a source for the system clock. Different clock domains can be independently
configured to run at different frequencies while enabling power saving by running each
peripheral at its optimal clock frequency.
The Atmel | SMART SAM D20 devices have two software-selectable sleep modes, idle and
standby. In idle mode the CPU is stopped while all other functions can be kept running. In
standby all clocks and functions are stopped expect those selected to continue running. The
device supports SleepWalking. This feature allows the peripheral to wake up from sleep
based on predefined conditions, and thus allows the CPU to wake up only when needed,
e.g. when a threshold is crossed or a result is ready. The Event System supports
synchronous and asynchronous events, allowing peripherals to receive, react to and send
events even in standby mode.
The Flash program memory can be reprogrammed in-system through the SWD interface.
The same interface can be used for non-intrusive on-chip debug of application code. A boot
loader running in the device can use any communication interface to download and upgrade
the application program in the Flash memory.
The Atmel | SMART SAM D20 devices are supported with a full suite of program and system
development tools, including C compilers, macro assemblers, program
debugger/simulators, programmers and evaluation kits.
Atmel-42129N–SAM-D20_datasheet–01/2015
SMART
Features
z Processor
ARM Cortex-M0+ CPU running at up to 48MHz
z Single-cycle hardware multiplier
Memories
z 16/32/64/128/256KB in-system self-programmable flash
z 2/4/8/16/32KB SRAM
System
z Power-on reset (POR) and brown-out detection (BOD)
z Internal and external clock options with 48MHz Digital Frequency Locked Loop (DFLL48M)
z External Interrupt Controller (EIC)
z 16 external interrupts
z One non-maskable interrupt
z Two-pin Serial Wire Debug (SWD) programming, test and debugging interface
Low Power
z Idle and standby sleep modes
z SleepWalking peripherals
Peripherals
z 8-channel Event System
z Up to eight 16-bit Timer/Counters (TC), configurable as either:
z
z
z
z
z
z
One 16-bit TC with compare/capture channels
One 8-bit TC with compare/capture channels
z One 32-bit TC with compare/capture channels, by using two TCs
z
z
z
z
z
z
z
z
z
32-bit Real Time Counter (RTC) with clock/calendar function
Watchdog Timer (WDT)
CRC-32 generator
Up to six Serial Communication Interfaces (SERCOM), each configurable to operate as either:
z USART with full-duplex and single-wire half-duplex configuration
2
z I C up to 400kHz
z SPI
One 12-bit, 350ksps Analog-to-Digital Converter (ADC) with up to 20 channels
z Differential and single-ended channels
z 1/2x to 16x gain stage
z Automatic offset and gain error compensation
z Oversampling and decimation in hardware to support 13-, 14-, 15- or 16-bit resolution
10-bit, 350ksps Digital-to-Analog Converter (DAC)
Two Analog Comparators with window compare function
Peripheral Touch Controller (PTC)
z
256-Channel capacitive touch and proximity sensing
z I/O
z
Up to 52 programmable I/O pins
z Packages
64-pin TQFP, QFN
64-ball UFBGA
z 48-pin TQFP, QFN
z 45-ball WLCSP
z 32-pin TQFP, QFN
z Operating Voltage
z 1.62V – 3.63V
z Power Consumption
z Down to 70µA/MHz in active mode
z Down to 8µA running the Peripheral Touch Controller
z
z
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
2
1.
Configuration Summary
Table 1-1.
Configuration Summary
SAM D20J
SAM D20G
SAM D20E
Number of pins
64
48
32
General Purpose I/O-pins (GPIOs)
52
38
26
Flash
256/128/64/32/16KB
256/128/64/32/16KB
256/128/64/32/16KB
SRAM
32/16/8/4/2KB
32/16/8/4/2KB
32/16/8/4/2KB
Maximum CPU frequency
48MHz
Event System channels
8
8
8
Timer Counter (TC)
8
6
6
Waveform output channels for TC
2
2
2
Serial Communication Interface
(SERCOM)
6
6
4
Analog-to-Digital Converter (ADC)
channels
20
14
10
Analog comparators
2
2
2
Digital-to-Analog Converter (DAC)
channels
1
1
1
Yes
Yes
Yes
1
1
1
1 32-bit value or
2 16-bit values
1 32-bit value or
2 16-bit values
1 32-bit value or
2 16-bit values
16
16
16
16x16
12x10
10x6
QFN
TQFP
UFBGA
QFN
TQFP
WLCSP
QFN
TQFP
Real-Time Counter (RTC)
RTC alarms
RTC compare values
External Interrupt lines
Peripheral Touch Controller (PTC) X
and Y lines
Packages
32.768kHz crystal oscillator (XOSC32K)
0.4-32MHz crystal oscillator (XOSC)
32.768kHzinternal oscillator (OSC32K)
32kHz ultra-low-power internal oscillator (OSCULP32K)
8MHz high-accuracy internal oscillator (OSC8M)
48MHz Digital Frequency Locked Loop (DFLL48M)
Oscillators
SW Debug Interface
Yes
Yes
Yes
Watchdog Timer (WDT)
Yes
Yes
Yes
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
3
2.
Ordering Information
SAMD 20 E 14 A - M U T
Product Family
Package Carrier
SAMD = General Purpose Microcontroller
No character = Tray (Default)
T = Tape and Reel
Product Series
20 = Cortex M0+ CPU, Basic Feature Set
Package Grade
O
Pin Count
U = -40 - 85 C Matte Sn Plating
N = -40 - 105 C Matte Sn Plating
O
E = 32 Pins
G = 48 Pins
J = 64 Pins
Package Type
Flash Memory Density
A = TQFP
M = QFN
C = UFBGA
U = WLCSP
18 = 256KB
17 = 128KB
16 = 64KB
15 = 32KB
14 = 16KB
Device Variant
A = Default Variant
2.1
SAM D20E
Ordering Code
FLASH (bytes)
SRAM (bytes)
Package
Carrier Type
ATSAMD20E14A-AU
Tray
ATSAMD20E14A-AN
TQFP32
ATSAMD20E14A-AUT
Tape & Reel
ATSAMD20E14A-ANT
16K
2K
ATSAMD20E14A-MU
Tray
ATSAMD20E14A-MN
QFN32
ATSAMD20E14A-MUT
Tape & Reel
ATSAMD20E14A-MNT
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
4
Ordering Code
FLASH (bytes)
SRAM (bytes)
Package
Carrier Type
ATSAMD20E15A-AU
Tray
ATSAMD20E15A-AN
TQFP32
ATSAMD20E15A-AUT
Tape & Reel
ATSAMD20E15A-ANT
32K
4K
ATSAMD20E15A-MU
Tray
ATSAMD20E15A-MN
QFN32
ATSAMD20E15A-MUT
Tape & Reel
ATSAMD20E15A-MNT
ATSAMD20E16A-AU
Tray
ATSAMD20E16A-AN
TQFP32
ATSAMD20E16A-AUT
Tape & Reel
ATSAMD20E16A-ANT
64K
8K
ATSAMD20E16A-MU
Tray
ATSAMD20E16A-MN
QFN32
ATSAMD20E16A-MUT
Tape & Reel
ATSAMD20E16A-MNT
ATSAMD20E17A-AU
Tray
ATSAMD20E17A-AN
TQFP32
ATSAMD20E17A-AUT
Tape & Reel
ATSAMD20E17A-ANT
128K
16K
ATSAMD20E17A-MU
Tray
ATSAMD20E17A-MN
QFN32
ATSAMD20E17A-MUT
Tape & Reel
ATSAMD20E17A-MNT
ATSAMD20E18A-AU
Tray
ATSAMD20E18A-AN
TQFP32
ATSAMD20E18A-AUT
Tape & Reel
ATSAMD20E18A-ANT
256K
32K
ATSAMD20E18A-MU
Tray
ATSAMD20E18A-MN
QFN32
ATSAMD20E18A-MUT
Tape & Reel
ATSAMD20E18A-MNT
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
5
2.2
SAM D20G
Ordering Code
FLASH (bytes)
SRAM (bytes)
Package
Carrier Type
ATSAMD20G14A-AU
Tray
ATSAMD20G14A-AN
TQFP48
ATSAMD20G14A-AUT
Tape & Reel
ATSAMD20G14A-ANT
16K
2K
ATSAMD20G14A-MU
Tray
ATSAMD20G14A-MN
QFN48
ATSAMD20G14A-MUT
Tape & Reel
ATSAMD20G14A-MNT
ATSAMD20G15A-AU
Tray
ATSAMD20G15A-AN
TQFP48
ATSAMD20G15A-AUT
Tape & Reel
ATSAMD20G15A-ANT
32K
4K
ATSAMD20G15A-MU
Tray
ATSAMD20G15A-MN
QFN48
ATSAMD20G15A-MUT
Tape & Reel
ATSAMD20G15A-MNT
ATSAMD20G16A-AU
Tray
ATSAMD20G16A-AN
TQFP48
ATSAMD20G16A-AUT
Tape & Reel
ATSAMD20G16A-ANT
64K
8K
ATSAMD20G16A-MU
Tray
ATSAMD20G16A-MN
QFN48
ATSAMD20G16A-MUT
Tape & Reel
ATSAMD20G16A-MNT
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
6
Ordering Code
FLASH (bytes)
SRAM (bytes)
Package
Carrier Type
ATSAMD20G17A-AU
Tray
ATSAMD20G17A-AN
TQFP48
ATSAMD20G17A-AUT
Tape & Reel
ATSAMD20G17A-ANT
ATSAMD20G17A-MU
128K
16K
Tray
ATSAMD20G17A-MN
QFN48
ATSAMD20G17A-MUT
Tape & Reel
ATSAMD20G17A-MNT
ATSAMD20G17A-UUT
WLCSP45
Tape & Reel
ATSAMD20G18A-AU
Tray
ATSAMD20G18A-AN
TQFP48
ATSAMD20G18A-AUT
Tape & Reel
ATSAMD20G18A-ANT
ATSAMD20G18A-MU
256K
32K
Tray
ATSAMD20G18A-MN
QFN48
ATSAMD20G18A-MUT
Tape & Reel
ATSAMD20G18A-MNT
ATSAMD20G18A-UUT
2.3
WLCSP45
Tape & Reel
Package
Carrier Type
SAM D20J
Ordering Code
FLASH (bytes)
SRAM (bytes)
ATSAMD20J14A-AU
Tray
ATSAMD20J14A-AN
TQFP64
ATSAMD20J14A-AUT
Tape & Reel
ATSAMD20J14A-ANT
16K
2K
ATSAMD20J14A-MU
Tray
ATSAMD20J14A-MN
QFN64
ATSAMD20J14A-MUT
Tape & Reel
ATSAMD20J14A-MNT
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
7
Ordering Code
FLASH (bytes)
SRAM (bytes)
Package
Carrier Type
ATSAMD20J15A-AU
Tray
ATSAMD20J15A-AN
TQFP64
ATSAMD20J15A-AUT
Tape & Reel
ATSAMD20J15A-ANT
32K
4K
ATSAMD20J15A-MU
Tray
ATSAMD20J15A-MN
QFN64
ATSAMD20J15A-MUT
Tape & Reel
ATSAMD20J15A-MNT
ATSAMD20J16A-AU
Tray
ATSAMD20J16A-AN
TQFP64
ATSAMD20J16A-AUT
Tape & Reel
ATSAMD20J16A-ANT
64K
8K
ATSAMD20J16A-MU
Tray
ATSAMD20J16A-MN
QFN64
ATSAMD20J16A-MUT
Tape & Reel
ATSAMD20J16A-MNT
ATSAMD20J17A-AU
Tray
ATSAMD20J17A-AN
TQFP64
ATSAMD20J17A-AUT
Tape & Reel
ATSAMD20J17A-ANT
ATSAMD20J17A-MU
128K
16K
Tray
ATSAMD20J17A-MN
QFN64
ATSAMD20J17A-MUT
Tape & Reel
ATSAMD20J17A-MNT
ATSAMD20J17A-CU
Tray
UFBGA64
ATSAMD20J17A-CUT
Tape & Reel
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
8
Ordering Code
FLASH (bytes)
SRAM (bytes)
Package
Carrier Type
ATSAMD20J18A-AU
Tray
ATSAMD20J18A-AN
TQFP64
ATSAMD20J18A-AUT
Tape & Reel
ATSAMD20J18A-ANT
ATSAMD20J18A-MU
256K
32K
Tray
ATSAMD20J18A-MN
QFN64
ATSAMD20J18A-MUT
Tape & Reel
ATSAMD20J18A-MNT
ATSAMD20J18A-CU
Tray
UFBGA64
ATSAMD20J18A-CUT
Tape & Reel
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
9
3.
Block Diagram
ARM SINGLE CYCLE IOBUS
SWCLK
ARM CORTEX-M0+
PROCESSOR
Fmax 48MHz
SERIAL
WIRE
SWDIO
DEVICE
SERVICE
UNIT
M
M
HIGH SPEED
BUS MATRIX
S
S
NVM
256/128/64/32/16KB
CONTROLLERFLASH
S
S
AHB-APB
BRIDGE A
32/16/8/4/2KB
RAM
S
AHB-APB
BRIDGE C
PERIPHERAL
ACCESS CONTROLLER
AHB-APB
BRIDGE B
PERIPHERAL
ACCESS CONTROLLER
PERIPHERAL
ACCESS CONTROLLER
PORT
SYSTEM CONTROLLER
VREF
BOD33
66xxSERCOM
SERCOM
PIN[3:0]
8 x TIMER COUNTER
8 x(See
Timer
Counter
Note1)
WO[1:0]
OSCULP32K
OSC32K
OSC8M
XIN
XOUT
XOSC
DFLL48M
POWER MANAGER
AIN[19:0]
ADC
RESET
RESET
CONTROLLER
GCLK_IO[7:0]
SLEEP
CONTROLLER
WATCHDOG
TIMER
EXTINT[15:0]
NMI
Notes:
1.
AIN[3:0]
2 ANALOG
COMPARATORS
GENERIC CLOCK
CONTROLLER
REAL TIME
COUNTER
EXTERNAL INTERRUPT
CONTROLLER
VREFA
VREFB
CLOCK
CONTROLLER
PORT
XOSC32K
EVENT SYSTEM
XIN32
XOUT32
CMP1:0]
VOUT
DAC
VREFA
PERIPHERAL
TOUCH
CONTROLLER
X[15:0]
Y[15:0]
Some products have different number of SERCOM instances, Timer/Counter instances, PTC signals and ADC signals. Refer to “Configuration Summary” on
page 3 for details.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
10
Pinout
4.1
SAM D20J
4.1.1
QFP64
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
PB03
PB02
PB01
PB00
PB31
PB30
PA31
PA30
VDDIN
VDDCORE
GND
PA28
RESET
PA27
PB23
PB22
4.
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
VDDIO
GND
PA25
PA24
PA23
PA22
PA21
PA20
PB17
PB16
PA19
PA18
PA17
PA16
VDDIO
GND
PA08
PA09
PA10
PA11
VDDIO
GND
PB10
PB11
PB12
PB13
PB14
PB15
PA12
PA13
PA14
PA15
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
PA00
PA01
PA02
PA03
PB04
PB05
GNDANA
VDDANA
PB06
PB07
PB08
PB09
PA04
PA05
PA06
PA07
DIGITAL PIN
ANALOG PIN
OSCILLATOR
GROUND
INPUT SUPPLY
REGULATED OUTPUT SUPPLY
RESET PIN
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
11
4.1.2
UFBGA64
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
12
SAM D20G
4.2.1
QFP48
48
47
46
45
44
43
42
41
40
39
38
37
PB03
PB02
PA31
PA30
VDDIN
VDDCORE
GND
PA28
RESET
PA27
PB23
PB22
4.2
36
35
34
33
32
31
30
29
28
27
26
25
1
2
3
4
5
6
7
8
9
10
11
12
VDDIO
GND
PA25
PA24
PA23
PA22
PA21
PA20
PA19
PA18
PA17
PA16
PA08
PA09
PA10
PA11
VDDIO
GND
PB10
PB11
PA12
PA13
PA14
PA15
13
14
15
16
17
18
19
20
21
22
23
24
PA00
PA01
PA02
PA03
GNDANA
VDDANA
PB08
PB09
PA04
PA05
PA06
PA07
DIGITAL PIN
ANALOG PIN
OSCILLATOR
GROUND
INPUT SUPPLY
REGULATED OUTPUT SUPPLY
RESET PIN
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
13
4.2.2
WLCSP45
"
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
14
32
31
30
29
28
27
26
25
PA31
PA30
VDDIN
VDDCORE
GND
PA28
RESET
PA27
SAM D20E
24
23
22
21
20
19
18
17
1
2
3
4
5
6
7
8
PA25
PA24
PA23
PA22
PA19
PA18
PA17
PA16
9
10
11
12
13
14
15
16
PA00
PA01
PA02
PA03
PA04
PA05
PA06
PA07
VDDANA
GND
PA08
PA09
PA10
PA11
PA14
PA15
4.3
DIGITAL PIN
ANALOG PIN
OSCILLATOR
GROUND
INPUT SUPPLY
REGULATED OUTPUT SUPPLY
RESET PIN
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
15
5.
I/O Multiplexing and Considerations
5.1
Multiplexed Signals
Each pin is by default controlled by the PORT as a general purpose I/O and alternatively it can be assigned to one of the
peripheral functions A, B, C, D, E, F, G or H. To enable a peripheral function on a pin, the Peripheral Multiplexer Enable
bit in the Pin Configuration register corresponding to that pin (PINCFGn.PMUXEN, n = 0-31) in the PORT must be written
to one. The selection of peripheral function A to H is done by writing to the Peripheral Multiplexing Odd and Even bits in
the Peripheral Multiplexing register (PMUXn.PMUXE/O) in the PORT. Refer to “PORT” on page 287 for details on how to
configure the I/O multiplexing.
Table 5-1 describes the peripheral signals multiplexed to the PORT I/O pins.
Table 5-1.
PORT Function Multiplexing
Pin
B(1)
A
SAM SAM SAM I/O
Pin
D20E D20G D20J Pin Supply Type
EIC
REF
ADC
AC
C
PTC DAC
D
E
SERCOM(2)
F
TC(3)
G
H
AC/GCLK
1
1
1
PA00 VDDANA
EXTINT[0]
SERCOM1/
PAD[0]
TC2/
WO[0]
2
2
2
PA01 VDDANA
EXTINT[1]
SERCOM1/
PAD[1]
TC2/
WO[1]
3
3
3
PA02 VDDANA
EXTINT[2]
AIN[0]
Y[0]
4
PA03 VDDANA
ADC/VREFA
EXTINT[3]
AIN[1]
DAC/VREFA
Y[1]
5
PB04 VDDANA
EXTINT[4]
AIN[12]
Y[10]
6
PB05 VDDANA
EXTINT[5]
AIN[13]
Y[11]
9
PB06 VDDANA
EXTINT[6]
AIN[14]
Y[12]
10
PB07 VDDANA
EXTINT[7]
AIN[15]
Y[13]
7
11
PB08 VDDANA
EXTINT[8]
AIN[2]
Y[14]
SERCOM4/
PAD[0]
TC4/
WO[0]
8
12
PB09 VDDANA
EXTINT[9]
AIN[3]
Y[15]
SERCOM4/
PAD[1]
TC4/
WO[1]
5
9
13
PA04 VDDANA
EXTINT[4]
AIN[4] AIN[0] Y[2]
SERCOM0/
PAD[0]
TC0/
WO[0]
6
10
14
PA05 VDDANA
EXTINT[5]
AIN[5] AIN[1] Y[3]
SERCOM0/
PAD[1]
TC0/
WO[1]
7
11
15
PA06 VDDANA
EXTINT[6]
AIN[6] AIN[2] Y[4]
SERCOM0/
PAD[2]
TC1/
WO[0]
8
12
16
PA07 VDDANA
EXTINT[7]
AIN[7] AIN[3] Y[5]
SERCOM0/
PAD[3]
TC1/
WO[1]
11
13
17
PA08
VDDIO
I2C
NMI
AIN[16]
X[0]
SERCOM0/ SERCOM2/
PAD[0]
PAD[0]
TC0/
WO[0]
12
14
18
PA09
VDDIO
I2C
EXTINT[9]
AIN[17]
X[1]
SERCOM0/ SERCOM2/
PAD[1]
PAD[1]
TC0/
WO[1]
13
15
19
PA10
VDDIO
EXTINT[10]
AIN[18]
X[2]
SERCOM0/ SERCOM2/
PAD[2]
PAD[2]
TC1/
WO[0]
GCLK_O[4]
14
16
20
PA11
VDDIO
EXTINT[11]
AIN[19]
X[3]
SERCOM0/ SERCOM2/
PAD[3]
PAD[3]
TC1/
WO[1]
GCLK_IO[5]
19
23
PB10
VDDIO
EXTINT[10]
SERCOM4/
PAD[2]
TC5/
WO[0]
GCLK_IO[4]
20
24
PB11
VDDIO
EXTINT[11]
SERCOM4/
PAD[3]
TC5/
WO[1]
GCLK_IO[5]
25
PB12
VDDIO
I2C
EXTINT[12]
X[12]
SERCOM4/
PAD[0]
TC4/
WO[0]
GCLK_IO[6]
26
PB13
VDDIO
I2C
EXTINT[13]
X[13]
SERCOM4/
PAD[1]
TC4/
WO[1]
GCLK_IO[7]
27
PB14
VDDIO
EXTINT[14]
X[14]
SERCOM4/
PAD[2]
TC5/
WO[0]
GCLK_IO[0]
4
4
ADC/
VREFB
VOUT
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Table 5-1.
PORT Function Multiplexing (Continued)
Pin
B(1)
A
SAM SAM SAM I/O
Pin
D20E D20G D20J Pin Supply Type
EIC
REF
ADC
AC
C
PTC DAC
D
E
SERCOM(2)
F
G
TC(3)
H
AC/GCLK
SERCOM4/
PAD[3]
TC5/
WO[1]
GCLK_IO[1]
EXTINT[12]
SERCOM2/ SERCOM4/
PAD[0]
PAD[0]
TC2/
WO[0]
AC/CMP[0]
EXTINT[13]
SERCOM2/ SERCOM4/
PAD[1]
PAD[1]
TC2/
WO[1]
AC/CMP[1]
VDDIO
EXTINT[14]
SERCOM2/ SERCOM4/
PAD[2]
PAD[2]
TC3/
WO[0]
GCLK_IO[0]
PA15
VDDIO
EXTINT[15]
SERCOM2/ SERCOM4/
PAD[3]
PAD[3]
TC3/
WO[1]
GCLK_IO[1]
35
PA16
VDDIO
I2C
EXTINT[0]
X[4]
SERCOM1/ SERCOM3/
PAD[0]
PAD[0]
TC2/
WO[0]
GCLK_IO[2]
26
36
PA17
VDDIO
I2C
EXTINT[1]
X[5]
SERCOM1/ SERCOM3/
PAD[1]
PAD[1]
TC2/
WO[1]
GCLK_IO[3]
19
27
37
PA18
VDDIO
EXTINT[2]
X[6]
SERCOM1/ SERCOM3/
PAD[2]
PAD[2]
TC3/
WO[0]
AC/CMP[0]
20
28
38
PA19
VDDIO
EXTINT[3]
X[7]
SERCOM1/ SERCOM3/
PAD[3]
PAD[3]
TC3/
WO[1]
AC/CMP[1]
39
PB16
VDDIO
I2C
EXTINT[0]
SERCOM5/
PAD[0]
TC6/
WO[0]
GCLK_IO[2]
40
PB17
VDDIO
I2C
EXTINT[1]
SERCOM5/
PAD[1]
TC6/
WO[1]
GCLK_IO[3]
29
41
PA20
VDDIO
EXTINT[4]
X[8]
SERCOM5/ SERCOM3/
PAD[2]
PAD[2]
TC7/
WO[0]
GCLK_IO[4]
30
42
PA21
VDDIO
EXTINT[5]
X[9]
SERCOM5/ SERCOM3/
PAD[3]
PAD[3]
TC7/
WO[1]
GCLK_IO[5]
21
31
43
PA22
VDDIO
I2C
EXTINT[6]
X[10]
SERCOM3/ SERCOM5/
PAD[0]
PAD[0]
TC4/
WO[0]
GCLK_IO[6]
22
32
44
PA23
VDDIO
I2C
EXTINT[7]
X[11]
SERCOM3/ SERCOM5/
PAD[1]
PAD[1]
TC4/
WO[1]
GCLK_IO[7]
23
33
45
PA24
VDDIO
EXTINT[12]
SERCOM3/ SERCOM5/
PAD[2]
PAD[2]
TC5/
WO[0]
24
34
46
PA25
VDDIO
EXTINT[13]
SERCOM3/ SERCOM5/
PAD[3]
PAD[3]
TC5/
WO[1]
37
49
PB22
VDDIO
EXTINT[6]
SERCOM5/
PAD[2]
TC7/
WO[0]
GCLK_IO[0]
38
50
PB23
VDDIO
EXTINT[7]
SERCOM5/
PAD[3]
TC7/
WO[1]
GCLK_IO[1]
25
39
51
PA27
VDDIO
EXTINT[15]
27
41
53
PA28
VDDIO
EXTINT[8]
28
PB15
VDDIO
EXTINT[15]
21
29
PA12
VDDIO
I2C
22
30
PA13
VDDIO
I2C
15
23
31
PA14
16
24
32
17
25
18
X[15]
GCLK_IO[0]
GCLK_IO[0]
31
45
57
PA30
VDDIO
EXTINT[10]
SERCOM1/
PAD[2]
32
46
58
PA31
VDDIO
EXTINT[11]
SERCOM1/
PAD[3]
TC1/
WO[1]
59
PB30
VDDIO
I2C
EXTINT[14]
SERCOM5/
PAD[0]
TC0/
WO[0]
60
PB31
VDDIO
I2C
EXTINT[15]
SERCOM5/
PAD[1]
TC0/
WO[1]
61
PB00 VDDANA
EXTINT[0]
AIN[8]
Y[6]
SERCOM5/
PAD[2]
TC7/
WO[0]
62
PB01 VDDANA
EXTINT[1]
AIN[9]
Y[7]
SERCOM5/
PAD[3]
TC7/
WO[1]
47
63
PB02 VDDANA
EXTINT[2]
AIN[10]
Y[8]
SERCOM5/
PAD[0]
TC6/
WO[0]
48
64
PB03 VDDANA
EXTINT[3]
AIN[11]
Y[9]
SERCOM5/
PAD[1]
TC6/
WO[1]
Note:
1.
TC1/
WO[0]
SWCLK GCLK_IO[0]
SWDIO(4)
All analog pin functions are on peripheral function B. Peripheral function B must be selected to disable the digital control of the pin.
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2.
3.
4.
Only some pins can be used in SERCOM I2C mode. See the Type column for using a SERCOM pin in I2C mode. Refer to the “I2C Pins” on page 582 for details
on the I2C pin characteristics
Note that TC6 and TC7 are not supported on the SAM D20G. Refer to “Configuration Summary” on page 3 for details.
This function is only activated in the presence of a debugger
5.2
Other Functions
5.2.1
Oscillator Pinout
The oscillators are not mapped to the normal PORT functions and their multiplexing are controlled by registers in the
System Controller (SYSCTRL). Refer to “SYSCTRL – System Controller” on page 134 for more information.
Oscillator
Supply
XOSC
VDDIO
XOSC32K
5.2.2
Signal
I/O Pin
XIN
PA14
XOUT
PA15
XIN32
PA00
XOUT32
PA01
VDDANA
Serial Wire Debug Interface Pinout
After reset, SWCLK functionality is selected for pin PA30 to allow for debugger probe detection. The application software
can switch the SWCLK functionality of PA30 to GPIO (or other peripherals) during runtime. PA31, by default, is configured like other normal I/O pins and will automatically switch to SWDIO function when a debugger cold-plugging or hotplugging is detected. When the device is put in debug mode, application software accesses to PA30 and PA31 PORT
registers are ignored.
Refer to “DSU – Device Service Unit” on page 43 for more information.
Signal
Supply
I/O Pin
SWCLK
VDDIO
PA30
SWDIO
VDDIO
PA31
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6.
Signal Descriptions List
The following table gives details on signal names classified by peripheral.
Table 6-1.
Signal Description List
Signal Name
Function
Type
Active Level
Analog Comparators - AC
AIN[3:0]
AC Analog Inputs
Analog
CMP[1:0]
AC Comparator Outputs
Digital
Analog Digital Converter - ADC
AIN[19:0]
ADC Analog Inputs
Analog
VREFA
ADC Voltage External Reference A
Analog
VREFB
ADC Voltage External Reference B
Analog
Digital Analog Converter - DAC
VOUT
DAC Voltage output
Analog
VREFA
DAC Voltage External Reference
Analog
External Interrupt Controller
EXTINT[15:0]
External Interrupts
Input
NMI
External Non-Maskable Interrupt
Input
Generic Clock Generator - GCLK
GCLK_IO[7:0]
Generic Clock (source clock or generic clock generator output)
I/O
Power Manager - PM
RESET
Reset
Input
Low
Serial Communication Interface - SERCOMx
PAD[3:0]
SERCOM I/O Pads
I/O
System Control - SYSCTRL
XIN
Crystal Input
Analog/ Digital
XIN32
32kHz Crystal Input
Analog/ Digital
XOUT
Crystal Output
Analog
XOUT32
32kHz Crystal Output
Analog
Waveform Outputs
Output
Timer Counter - TCx
WO[1:0]
Peripheral Touch Controller - PTC
X[15:0]
PTC Input
Analog
Y[15:0]
PTC Input
Analog
General Purpose I/O - PORT
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Table 6-1.
Signal Description List (Continued)
Signal Name
Function
Type
PA25 - PA00
Parallel I/O Controller I/O Port A
I/O
PA28 - PA27
Parallel I/O Controller I/O Port A
I/O
PA31 - PA30
Parallel I/O Controller I/O Port A
I/O
PB17 - PB00
Parallel I/O Controller I/O Port B
I/O
PB23 - PB22
Parallel I/O Controller I/O Port B
I/O
PB31 - PB30
Parallel I/O Controller I/O Port B
I/O
Active Level
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ADC
PA[7:2]
VDDIO
VDDIN
GND
Power Domain Overview
VDDCORE
7.1
GNDANA
Power Supply and Start-Up Considerations
VDDANA
7.
VOLTAGE
REGULATOR
PB[31:10]
OSC8M
PA[13:8]
BOD12
XOSC
AC
PB[9:0]
PA[15:14]
PA[31:16]
DAC
PTC
Digital Logic
(CPU, peripherals)
PA[1:0]
XOSC32K
POR
OSC32K
OSCULP32K
7.2
Power Supply Considerations
7.2.1
Power Supplies
DFLL48M
BOD33
The Atmel® SAM D20 has several different power supply pins:
z
VDDIO: Powers I/O lines, OSC8M and XOSC. Voltage is 1.62V to 3.63V.
z
VDDIN: Powers I/O lines and the internal regulator. Voltage is 1.62V to 3.63V.
z
VDDANA: Powers I/O lines and the ADC, AC, DAC, PTC, OSCULP32K, OSC32K, XOSC32K. Voltage is 1.62V to
3.63V.
z
VDDCORE: Internal regulated voltage output. Powers the core, memories and peripherals. Voltage is 1.2V.
The same voltage must be applied to both VDDIN, VDDIO and VDDANA. This common voltage is referred to as VDD in
the datasheet.
The ground pins, GND, are common to VDDCORE, VDDIO and VDDIN. The ground pin for VDDANA is GNDANA.
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For decoupling recommendations for the different power supplies, refer to the schematic checklist.
Refer to “Schematic Checklist” on page 620 for details.
7.2.2
Voltage Regulator
The voltage regulator has two different modes:
7.2.3
z
Normal mode: To be used when the CPU and peripherals are running
z
Low Power (LP) mode: To be used when the regulator draws small static current. It can be used in standby mode
Typical Powering Schematics
The SAM D20 uses a single supply from 1.62V to 3.63V.
The following figure shows the recommended power supply connection.
Figure 7-1. Power Supply Connection
SAM D20
Main Supply
(1.62V — 3.63V)
VDDIO
VDDANA
VDDIN
VDDCORE
GND
GNDANA
7.2.4
Power-Up Sequence
7.2.4.1
Minimum Rise Rate
The integrated power-on reset (POR) circuitry monitoring the VDDANA power supply requires a minimum rise rate. Refer
to the “Electrical Characteristics” on page 571 for details.
7.2.4.2
Maximum Rise Rate
The rise rate of the power supply must not exceed the values described in Electrical Characteristics. Refer to the
“Electrical Characteristics” on page 571 for details.
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7.3
Power-Up
This section summarizes the power-up sequence of the SAM D20. The behavior after power-up is controlled by the
Power Manager. Refer to “PM – Power Manager” on page 107 for details.
7.3.1
Starting of Clocks
After power-up, the device is set to its initial state and kept in reset, until the power has stabilized throughout the device.
Once the power has stabilized, the device will use a 1MHz clock. This clock is derived from the 8MHz Internal Oscillator
(OSC8M), which is divided by eight and used as a clock source for generic clock generator 0. Generic clock generator 0
is the main clock for the Power Manager (PM).
Some synchronous system clocks are active, allowing software execution.
Refer to the “Clock Mask Register” section in “PM – Power Manager” on page 107 for the list of default peripheral clocks
running. Synchronous system clocks that are running are by default not divided and receive a 1MHz clock through
generic clock generator 0. Other generic clocks are disabled except GCLK_WDT, which is used by the Watchdog Timer
(WDT).
7.3.2
I/O Pins
After power-up, the I/O pins are tri-stated.
7.3.3
Fetching of Initial Instructions
After reset has been released, the CPU starts fetching PC and SP values from the reset address, which is 0x00000000.
This address points to the first executable address in the internal flash. The code read from the internal flash is free to
configure the clock system and clock sources. Refer to “PM – Power Manager” on page 107, “GCLK – Generic Clock
Controller” on page 85 and “SYSCTRL – System Controller” on page 134 for details. Refer to the ARM Architecture
Reference Manual for more information on CPU startup (http://www.arm.com).
7.4
Power-On Reset and Brown-Out Detector
The SAM D20 embeds three features to monitor, warn and/or reset the device:
7.4.1
z
POR: Power-on reset on VDDANA
z
BOD33: Brown-out detector on VDDANA
z
BOD12: Voltage Regulator Internal Brown-out detector on VDDCORE. The Voltage Regulator Internal BOD is
calibrated in production and its calibration configuration is stored in the NVM User Row. This configuration should
not be changed if the user row is written to assure the correct behavior of the BOD12.
Power-On Reset on VDDANA
POR monitors VDDANA. It is always activated and monitors voltage at startup and also during all the sleep modes. If
VDDANA goes below the threshold voltage, the entire chip is reset.
7.4.2
Brown-Out Detector on VDDANA
BOD33 monitors VDDANA. Refer to “SYSCTRL – System Controller” on page 134 for details.
7.4.3
Brown-Out Detector on VDDCORE
Once the device has started up, BOD12 monitors the internal VDDCORE.
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8.
Product Mapping
Figure 8-1. SAM D20 Product Mapping
Global Memory Space
0x00000000
Code
0x00000000
Internal flash
Code
0x20000000
0x00040000
Reserved
SRAM
0x1FFFFFFF
SRAM
0x20008000
0x20000000
Undefined
0x40000000
AHB-APB Bridge C
Internal SRAM
0x42000000
PAC2
0x20008000
0x42000400
Peripherals
EVSYS
Peripherals
0x42000800
0x40000000
0x43000000
SERCOM0
AHB-APB
Bridge A
Reserved
0x42000C00
SERCOM1
0x42001000
0x41000000
0x60000000
SERCOM2
AHB-APB
Bridge B
Undefined
0x42001400
SERCOM3
0x42000000
0x60000200
Reserved
SERCOM4
AHB-APB
Bridge C
0xE0000000
System
0x42001800
0x42001C00
SERCOM5
0x42FFFFFF
0x42002000
0xFFFFFFFF
TC0
System
0x42002400
0xE0000000
TC1
Reserved
0x42002800
0xE000E000
TC2
SCS
0x42002C00
0xE000F000
TC3
Reserved
AHB-APB Bridge A
0x40000000
PAC0
0x42003000
0xE00FF000
TC4
ROM Table
0x42003400
0xE0100000
TC5
Reserved
0xFFFFFFFF
0x40000400
0x42003800
TC6
PM
0x40000800
SYSCTRL
AHB-APB Bridge B
0x42004800
0x41004000
0x41004400
0x42004C00
PORT
EIC
0x41004800
0x40001C00
DAC
NVMCTRL
RTC
0x40001800
AC
DSU
WDT
Reserved
0x40FFFFFF
0x42004400
0x41002000
0x40001400
ADC
PAC1
GCLK
0x40001000
TC7
0x42004000
0x41000000
0x40000C00
0x42003C00
PTC
0x42005000
Reserved
0x41FFFFFF
Reserved
0x42FFFFFF
This figure represents the full configuration of the Atmel® SAM D20 with maximum flash and SRAM capabilities and a full
set of peripherals. Refer to the “Configuration Summary” on page 3 for details.
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9.
Memories
9.1
Embedded Memories
9.2
z
Internal high-speed flash
z
Internal high-speed RAM, single-cycle access at full speed
z
Dedicated flash area for EEPROM emulation
Physical Memory Map
The High-Speed bus is implemented as a Bus Matrix. Refer to “High-Speed Bus Matrix” on page 31 for details. All HighSpeed bus addresses are fixed, and they are never remapped. The 32-bit physical address space is mapped as follows:
Table 9-1.
SAM D20 Physical Memory Map(1)
Size
Memory
Start address
SAMD20x18
SAMD20x17
SAMD20x16
SAMD20x15
SAMD20x14
Embedded Flash
0x00000000
256KB
128KB
64KB
32KB
16KB
Embedded SRAM
0x20000000
32KB
16KB
8KB
4KB
2KB
AHB-APB Bridge A
0x40000000
64KB
64KB
64KB
64KB
64KB
AHB-APB Bridge B
0x41000000
64KB
64KB
64KB
64KB
64KB
AHB-APB Bridge C
0x42000000
64KB
64KB
64KB
64KB
64KB
Note:
1.
Table 9-2.
x = G, J or E. Refer to “Ordering Information” on page 4 for details.
Flash Memory Parameters(1)
Device
Flash Size
Number of Pages (NVMP)
Page Size (PSZ)
Row Size
ATSAMD20x18
256KB
4096
64 bytes
4 pages = 256 bytes
ATSAMD20x17
128KB
2048
64 bytes
4 pages = 256 bytes
ATSAMD20x16
64KB
1024
64 bytes
4 pages = 256 bytes
ATSAMD20x15
32KB
512
64 bytes
4 pages = 256 bytes
ATSAMD20x14
16KB
256
64 bytes
4 pages = 256 bytes
Notes:
1.
2.
x = G, J or E. Refer to “Ordering Information” on page 4 for details.
The number of pages (NVMP) and page size (PSZ) can be read from the NVM Pages and Page Size bits in the NVM Parameter register in the
NVMCTRL (PARAM.NVMP and PARAM.PSZ, respectively). Refer to PARAM for details.
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Figure 9-1. Calibration and Auxiliary space
AUX1
0x00806040
0x00800000
Calibration and
auxiliary space
Area 4: Software
calibration area (256bits)
NVM base address +
0x00800000
0x00806020
Area 4 offset address
Area 3: Reserved
(128bits)
NVM base address
+ NVM size
0x00806010
NVM main address
space
Area 2: Device configuration
area (64 bits)
0x00806008
Area 2 offset address
Area 1: Reserved (64 bits)
0x00806000
0x00000000
Area 3 offset address
Area 1 address offset
NVM Base Address
0x00806000
AUX1
AUX1 offset address
0x00804000
AUX0 – NVM User
Row
0x00800000
Automatic calibration
row
AUX0 offset address
Calibration and auxiliary
space address offset
The values from the automatic calibration row is loaded into their respective registers on startup.
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9.3
Non-Volatile Memory (NVM) User Row Mapping
The NVM User Row contains calibration data that are automatically read at device power on.
The NVM User Row can be read at address 0x804000.
To write the NVM User Row refer to “NVMCTRL – Non-Volatile Memory Controller” on page 265.
Note that when writing to the User Row the values will only be loaded at device reset.
Table 9-3.
NVM User Row Mapping
Bit Position
Name
Description
2:0
BOOTPROT
3
Reserved
6:4
EEPROM
7
Reserved
13:8
BOD33 Level
BOD33 Threshold Level (BOD33.LEVEL) at power on. Refer to BOD33
register. Default value = 7.
14
BOD33 Enable
BOD33 Enable at power on. Refer to BOD33 register. Default value = 1.
16:15
BOD33 Action
BOD33 Action at power on. Refer to BOD33 register. Default value = 1.
24:17
Reserved
Voltage Regulator Internal BOD(BOD12) configuration. These bits are written
in production and must not be changed. Default value = 0x70.
25
WDT Enable
WDT Enable at power on. Refer to WDT CTRL register. Default value = 0.
26
WDT Always-On
WDT Always-On at power on. Refer to WDT CTRL register. Default value = 0.
30:27
WDT Period
WDT Period at power on. Refer to WDT CONFIG register. Default
value = 0xB.
34:31
WDT Window
WDT Window mode time-out at power on. Refer to WDT CONFIG register.
Default value, WINDOW_1 = 0x5.
38:35
WDT EWOFFSET
WDT Early Warning Interrupt Time Offset at power on. Refer to WDT
EWCTRL register. Default value = 0xB.
39
WDT WEN
WDT Timer Window Mode Enable at power on. Refer to WDT CTRL register.
Default value = 0.
40(1)
BOD33 Hysteresis
BOD33 Hysteresis configuration at power on. Refer to BOD33 register. Default
value = 0.
41(2)
Reserved
Voltage Regulator Internal BOD(BOD12) configuration. This bit is written in
production and must not be changed. Default value = 0.
47:42
Reserved
63:48
LOCK
Used to select one of eight different bootloader sizes. Refer to “NVMCTRL –
Non-Volatile Memory Controller” on page 265. Default value = 7.
Used to select one of eight different EEPROM area sizes. Refer to
Notes:
1.
2.
“NVMCTRL – Non-Volatile Memory Controller” on page 265. Default
value = 7.
NVM Region Lock Bits. Refer to “NVMCTRL – Non-Volatile Memory
Controller” on page 265. Default value = 0xFFFF.
On rev C: Bit 40 is “Reserved” and Default value = 1.
On rev C: Bit 41 is “Reserved” and Default value = 1.
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9.4
NVM Software Calibration Area Mapping
The NVM Software Calibration Area contains calibration data that are measured and written during production test.
These calibration values should be read by the application software and written back to the corresponding register.
The NVM Software Calibration Area can be read at address 0x806020.
The NVM Software Calibration Area can not be written.
Table 9-4.
Bit Position
Name
2:0
Reserved
14:3
Reserved
26:15
Reserved
34:27
ADC LINEARITY
ADC Linearity Calibration. Should be written to CALIB register.
37:35
ADC BIASCAL
ADC Bias Calibration. Should be written to CALIB register.
44:38
OSC32K CAL
OSC32KCalibration. Should be written to OSC32K register.
57:45
Reserved
63:58
DFLL48M COARSE CAL(1)
DFLL48M Coarse calibration value. Should be written to the DFLLVAL
register.
73:64
DFLL48M FINE CAL(1)
DFLL48M Fine calibration value. Should be written to the DFLLVAL register.
127:74
Reserved
Note:
9.5
NVM Software Calibration Area Mapping
1.
Description
Not applicable for silicon rev C and previous.
Serial Number
Each device has a unique 128-bit serial number which is a concatenation of four 32-bit words contained at the following
addresses:
Word 0: 0x0080A00C
Word 1: 0x0080A040
Word 2: 0x0080A044
Word 3: 0x0080A048
The uniqueness of the serial number is guaranteed only when using all 128 bits.
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10.
Processor and Architecture
10.1
Cortex-M0+ Processor
The Atmel® SAM D20 implements the ARM® Cortex®-M0+ processor, which is based on the ARMv6 architecture and
Thumb®-2 ISA. The Cortex M0+ is 100% instruction set compatible with its predecessor, the Cortex-M0 processor, and
upward compatible with the Cortex-M3 and Cortex-M4 processors. The ARM Cortex-M0+ implemented is revision r0p1.
For more information, refer to www.arm.com.
10.1.1 Cortex-M0+ Configuration
Feature
Configurable Option
SAM D20 Configuration
Interrupts
External interrupts 0-32
32
Data endianness
Little-endian or big-endian
Little-endian
SysTick timer
Present or absent
Present
Number of watchpoint comparators
0, 1, 2
2
Number of breakpoint comparators
0, 1, 2, 3, 4
4
Halting debug support
Present or absent
Present
Multiplier
Fast or small
Fast (single cycle)
Single-cycle I/O port
Present or absent
Present
Wake-up interrupt controller
Supported or not supported
Not supported
Vector Table Offset Register
Present or absent
Present
Unprivileged/Privileged support
Present or absent
Absent
Memory Protection Unit
Not present or 8-region
Not present
Reset all registers
Present or absent
Absent(1)
Instruction fetch width
16-bit only or mostly 32-bit
32-bit
Note:
1.
All software run in privileged mode only
The ARM Cortex-M0+ processor has two bus interfaces:
z
Single 32-bit AMBA® 3 AHB-Lite™ system interface that provides connections to peripherals and all system
memory, including flash and RAM
z
Single 32-bit I/O port bus interfacing to the PORT with one-cycle loads and stores
10.1.2 Cortex-M0+ Peripherals
z
System Control Space (SCS)
z
z
System Timer (SysTick)
z
z
The processor provides debug through registers in the SCS. Refer to the Cortex-M0+ Technical Reference
Manual for details (www.arm.com).
The System Timer is a 24-bit timer that extends the functionality of both the processor and the NVIC. Refer
to the Cortex-M0+ Technical Reference Manual for details (www.arm.com).
Nested Vectored Interrupt Controller (NVIC)
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z
z
External interrupt signals connect to the NVIC, and the NVIC prioritizes the interrupts. Software can set the
priority of each interrupt. The NVIC and the Cortex-M0+ processor core are closely coupled, providing low
latency interrupt processing and efficient processing of late arriving interrupts. Refer to “Nested Vector
Interrupt Controller” on page 30 and the Cortex-M0+ Technical Reference Manual for details
(www.arm.com).
System Control Block (SCB)
z
The System Control Block provides system implementation information, and system control. This includes
configuration, control, and reporting of the system exceptions. Refer to the Cortex-M0+ Devices Generic
User Guide for details (www.arm.com).
10.1.3 Cortex-M0+ Address Map
Table 10-1. Cortex-M0+ Address Map
Address
Peripheral
0xE000E000
System Control Space (SCS)
0xE000E010
System Timer (SysTick)
0xE000E100
Nested Vectored Interrupt Controller (NVIC)
0xE000ED00
System Control Block (SCB)
10.1.4 I/O Interface
10.1.4.1 Overview
Because accesses to the AMBA® AHB™-Lite and the single-cycle I/O interface can be made concurrently, the CortexM0+ processor can fetch the next instructions while accessing the I/Os. This enables single-cycle I/O accesses to be
sustained for as long as needed.
10.1.4.2 Description
Direct access to PORT registers.
10.2
Nested Vector Interrupt Controller
10.2.1 Overview
The Nested Vectored Interrupt Controller (NVIC) in the SAM D20 supports 32 interrupt lines with four different priority
levels. For more details, refer to the Cortex-M0+ Technical Reference Manual (www.arm.com).
10.2.2 Interrupt Line Mapping
Each of the 32 interrupt lines is connected to one peripheral instance, as shown in the table below. Each peripheral can
have one or more interrupt flags, located in the peripheral’s Interrupt Flag Status and Clear (INTFLAG) register. The
interrupt flag is set when the interrupt condition occurs. Each interrupt in the peripheral can be individually enabled by
writing a one to the corresponding bit in the peripheral’s Interrupt Enable Set (INTENSET) register, and disabled by
writing a one to the corresponding bit in the peripheral’s Interrupt Enable Clear (INTENCLR) register. An interrupt request
is generated from the peripheral when the interrupt flag is set and the corresponding interrupt is enabled. The interrupt
requests for one peripheral are ORed together on system level, generating one interrupt request for each peripheral. An
interrupt request will set the corresponding interrupt pending bit in the NVIC interrupt pending registers
(SETPEND/CLRPEND bits in ISPR/ICPR). For the NVIC to activate the interrupt, it must be enabled in the NVIC interrupt
enable register (SETENA/CLRENA bits in ISER/ICER). The NVIC interrupt priority registers IPR0-IPR7 provide a priority
field for each interrupt.
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Peripheral Source
NVIC Line
EIC NMI – External Interrupt Controller Non Maskable Interrupt
10.3
NMI
PM – Power Manager
0
SYSCTRL – System Controller
1
WDT – Watchdog Timer
2
RTC – Real Time Counter
3
EIC – External Interrupt Controller
4
NVMCTRL – Non-Volatile Memory Controller
5
EVSYS – Event System
6
SERCOM0 – Serial Communication Interface 0
7
SERCOM1 – Serial Communication Interface 1
8
SERCOM2 – Serial Communication Interface 2
9
SERCOM3 – Serial Communication Interface 3
10
SERCOM4 – Serial Communication Interface 4
11
SERCOM5 – Serial Communication Interface 5
12
TC0 – Timer/Counter 0
13
TC1 – Timer/Counter 1
14
TC2 – Timer/Counter 2
15
TC3 – Timer/Counter 3
16
TC4 – Timer/Counter 4
17
TC5 – Timer/Counter 5
18
TC6 – Timer/Counter 6
19
TC7 – Timer/Counter 7
20
ADC – Analog-to-Digital Converter
21
AC – Analog Comparator
22
DAC – Digital-to-Analog Converter
23
PTC – Peripheral Touch Controller
24
High-Speed Bus Matrix
10.3.1 Features
The High-Speed Bus Matrix includes these features:
z
Symmetric crossbar bus switch implementation
z
Allows concurrent accesses from different masters to different slaves
z
32-bit data bus
z
Operation at a one-to-one clock frequency with the bus masters
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10.3.2 Configuration
High-Speed Bus
Masters
CM0+
0
DSU
1
Internal Flash
AHB-APB Bridge A
AHB-APB Bridge B
AHB-APB Bridge C
Internal SRAM
High-Speed Bus Slaves
0
1
2
3
4
Table 10-2. Bus Matrix Masters
Bus Matrix Masters
Master ID
CM0+ - Cortex M0+ Processor
0
DSU - Device Service Unit
1
Table 10-3. Bus Matrix Slaves
Bus Matrix Slaves
Slave ID
Internal Flash Memory
0
AHB-APB Bridge A
1
AHB-APB Bridge B
2
AHB-APB Bridge C
3
Internal SRAM
4
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10.4
AHB-APB Bridge
The AHB-APB bridge is an AHB slave, providing an interface between the high-speed AHB domain and the low-power
APB domain. It is used to provide access to the programmable control registers of peripherals (see “Product Mapping” on
page 24).
AHB-APB bridge is based on AMBA APB Protocol Specification V2.0 (ref. as APB4) including:
z Wait state support
z Error reporting
z Transaction protection
z Sparse data transfer (byte, half-word and word)
Additional enhancements:
z Address and data cycles merged into a single cycle
z Sparse data transfer also apply to read access
to operate the AHB-APB bridge, the clock (CLK_HPBx_AHB) must be enabled. See “PM – Power Manager” on page 107
for details.
Figure 10-1. APB Write Access.
T0
T1
T2
PCLK
PADDR
T3
T0
T2
T3
T4
T5
PCLK
Addr 1
PADDR
PWRITE
PWRITE
PSEL
PSEL
PENABLE
PENABLE
PWDATA
T1
Data 1
PREADY
PWDATA
Addr 1
Data 1
PREADY
No wait states
Wait states
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Figure 10-2. APB Read Access.
T0
T1
T2
T3
T0
PCLK
PADDR
Addr 1
PADDR
PWRITE
PSEL
PSEL
PENABLE
PENABLE
Data 1
PREADY
T3
T4
T5
Addr 1
PRDATA
Data 1
PREADY
No wait states
10.5
T2
PCLK
PWRITE
PRDATA
T1
Wait states
PAC – Peripheral Access Controller
10.5.1 Overview
There is one PAC associated with each AHB-APB bridge. The PAC can provide write protection for registers of each
peripheral connected on the same bridge.
The PAC peripheral bus clock (CLK_PACx_APB) can be enabled and disabled in the Power Manager. CLK_PAC0_APB
and CLK_PAC1_APB are enabled are reset. CLK_PAC2_APB is disabled at reset. Refer to “PM – Power Manager” on
page 107 for details. The PAC will continue to operate in any sleep mode where the selected clock source is running.
Write-protection does not apply for debugger access. When the debugger makes an access to a peripheral, writeprotection is ignored so that the debugger can update the register.
Write-protect registers allow the user to disable a selected peripheral’s write-protection without doing a read-modify-write
operation. These registers are mapped into two I/O memory locations, one for clearing and one for setting the register
bits. Writing a one to a bit in the Write Protect Clear register (WPCLR) will clear the corresponding bit in both registers
(WPCLR and WPSET) and disable the write-protection for the corresponding peripheral, while writing a one to a bit in the
Write Protect Set (WPSET) register will set the corresponding bit in both registers (WPCLR and WPSET) and enable the
write-protection for the corresponding peripheral. Both registers (WPCLR and WPSET) will return the same value when
read.
If a peripheral is write-protected, and if a write access is performed, data will not be written, and the peripheral will return
an access error (CPU exception).
The PAC also offers a safety feature for correct program execution, with a CPU exception generated on double writeprotection or double unprotection of a peripheral. If a peripheral n is write-protected and a write to one in WPSET[n] is
detected, the PAC returns an error. This can be used to ensure that the application follows the intended program flow by
always following a write-protect with an unprotect, and vice versa. However, in applications where a write-protected
peripheral is used in several contexts, e.g., interrupts, care should be taken so that either the interrupt can not happen
while the main application or other interrupt levels manipulate the write-protection status, or when the interrupt handler
needs to unprotect the peripheral, based on the current protection status, by reading WPSET.
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10.6
Register Description
Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters and 16-bit halves of a 32-bit register, and
the 8-bit halves of a 16-bit register can be accessed directly.
Refer to “Product Mapping” on page 24 for PAC locations.
10.6.1 Write Protect Clear
Name:
WPCLR
Offset:
0x00
Reset:
0x00000000
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
EIC
RTC
WDT
GCLK
SYSCTRL
PM
Access
R
R/W
R/W
R/W
R/W
R/W
R/W
R
Reset
0
0
0
0
0
0
0
0
z
Bits 31:7 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 6:1 – EIC, RTC, WDT, GCLK, SYSCTRL, PM: Write Protect Disable
0: Write-protection is disabled.
1: Write-protection is enabled.
Writing a zero to these bits has no effect.
Writing a one to these bits will clear the Write Protect bits for the corresponding peripherals.
z
Bit 0 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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10.6.2 Write Protect Set
Name:
WPSET
Offset:
0x04
Reset:
0x00000000
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
EIC
RTC
WDT
GCLK
SYSCTRL
PM
Access
R
R/W
R/W
R/W
R/W
R/W
R/W
R
Reset
0
0
0
0
0
0
0
0
z
Bits 31:7 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 6:1 – EIC, RTC, WDT, GCLK, SYSCTRL, PM: Write Protect Enable
0: Write-protection is disabled.
1: Write-protection is enabled.
Writing a zero to these bits has no effect.
Writing a one to these bits will set the Write Protect bit for the corresponding peripherals.
z
Bit 0 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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10.6.3 PAC1 Register Description
Write Protect Clear
Name:
WPCLR
Offset:
0x00
Reset:
0x00000002
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
PORT
NVMCTRL
DSU
Access
R
R
R
R
R/W
R/W
R/W
R
Reset
0
0
0
0
0
0
1
0
z
Bits 31:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 3:1 – PORT, NVMCTRL, DSU: Write Protect
0: Write-protection is disabled.
1: Write-protection is enabled.
Writing a zero to these bits has no effect.
Writing a one to these bits will clear the Write Protect bit for the corresponding peripherals.
z
Bit 0 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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Write Protect Set
Name:
WPSET
Offset:
0x04
Reset:
0x00000002
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
PORT
NVMCTRL
DSU
Access
R
R
R
R
R/W
R/W
R/W
R
Reset
0
0
0
0
0
0
1
0
z
Bits 31:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 3:1 – PORT, NVMCTRL, DSU: Write Protect
0: Write-protection is disabled.
1: Write-protection is enabled.
Writing a zero to these bits has no effect.
Writing a one to these bits will set the Write Protect bit for the corresponding peripherals.
z
Bit 0 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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10.6.4 PAC2 Register Description
Write Protect Clear
Name:
WPCLR
Offset:
0x00
Reset:
0x00100000
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
PTC
DAC
AC
ADC
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
1
0
0
0
0
Bit
15
14
13
12
11
10
9
8
TC7
TC6
TC5
TC4
TC3
TC2
TC1
TC0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
SERCOM5
SERCOM4
SERCOM3
SERCOM2
SERCOM1
SERCOM0
EVSYS
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R
0
0
0
0
0
0
0
0
Access
Access
Reset
z
Bits 31:20 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
reset value when this register is written. These bits will always return reset value when read.
z
Bits 19:1 – PTC, DAC, AC, ADC, TC7, TC6, TC5, TC4, TC3, TC2, TC1, TC0, SERCOM5, SERCOM4,
SERCOM3, SERCOM2, SERCOM1, SERCOM0, EVSYS: Write Protect
0: Write-protection is disabled.
1: Write-protection is enabled.
Writing a zero to these bits has no effect.
Writing a one to these bits will clear the Write Protect bit for the corresponding peripherals.
z
Bit 0 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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Write Protect Set
Name:
WPSET
Offset:
0x04
Reset:
0x00100000
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
PTC
DAC
AC
ADC
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
1
0
0
0
0
Bit
15
14
13
12
11
10
9
8
TC7
TC6
TC5
TC4
TC3
TC2
TC1
TC0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
SERCOM5
SERCOM4
SERCOM3
SERCOM2
SERCOM1
SERCOM0
EVSYS
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R
0
0
0
0
0
0
0
0
Access
Access
Reset
z
Bits 31:20 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
reset value when this register is written. These bits will always return reset value when read.
z
Bits 19:1 – PTC, DAC, AC, ADC, TC7, TC6, TC5, TC4, TC3, TC2, TC1, TC0, SERCOM5, SERCOM4,
SERCOM3, SERCOM2, SERCOM1, SERCOM0, EVSYS: Write Protect Enable
0: Write-protection is disabled.
1: Write-protection is enabled.
Writing a zero to these bits has no effect.
Writing a one to these bits will set the Write Protect bit for the corresponding peripherals.
z
Bit 0 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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11.
Peripherals Configuration Overview
The following table shows an overview of all the peripherals in the device. The IRQ Line column shows the interrupt
mapping, as described in “Nested Vector Interrupt Controller” on page 30.
The AHB and APB clock indexes correspond to the bit in the AHBMASK and APBMASK (x = A, B or C) registers in the
Power Manager, while the Enabled at Reset column shows whether the peripheral clock is enabled at reset (Y) or not
(N). Refer to the Power Manager AHBMASK, APBAMASK, APBBMASK and APBCMASK registers for details.
The Generic Clock Index column corresponds to the value of the Generic Clock Selection ID bits in the Generic Clock
Control register (CLKCTRL.ID) in the Generic Clock Controller. Refer to the GCLK CLKCTRL register description for
details.
The PAC Index column corresponds to the bit in the PACi (i = 0, 1 or 2) registers, while the Prot at Reset column shows
whether the peripheral is protected at reset (Y) or not (N). Refer to “PAC – Peripheral Access Controller” on page 34 for
details.
The numbers in the Events User column correspond to the value of the User Multiplexer Selection bits in the User
Multiplexer register (USER.USER) in the Event System. See the USER register description and Table 22-6 for details.
The numbers in the Events Generator column correspond to the value of the Event Generator bits in the Channel register
(CHANNEL.EVGEN) in the Event System. See the CHANNEL register description and Table 22-3 for details.
Table 11-1. Peripherals Configuration Overview
AHB Clock
IRQ
Line
APB Clock
Enabled
Enabled
Index at Reset Index at Reset
Generic
Clock
Peripheral
Name
Base
Address
AHB-APB
Bridge A
0x40000000
PAC0
0x40000000
0
Y
PM
0x40000400
0
1
Y
SYSCTRL
0x40000800
1
2
Y
GCLK
0x40000C00
3
Y
WDT
0x40001000
2
4
Y
1
RTC
0x40001400
3
5
Y
EIC
0x40001800
NMI,
4
6
Y
AHB-APB
Bridge B
0x41000000
PAC1
0x41000000
DSU
0x41002000
NVMCTRL
0x41004000
PORT
0x41004400
AHB-APB
Bridge C
0x42000000
PAC2
0x42000000
EVSYS
0x42000400
SERCOM0
0
PAC
Events
Index
Prot at
Reset
1
N
Y
2
N
Y
3
N
Y
4
N
2
5
N
1: CMP0/ALARM0
2: CMP1
3: OVF
4-11: PER0-7
Y
3
6
N
12-27: EXTINT0-15
Y
Index
User
Generator
Sleep
Walking
Y
0: DFLL48M
reference
1
Y
0
Y
3
Y
1
Y
1
Y
4
Y
2
Y
2
N
3
Y
3
N
0
N
6
1
N
4-11: one
per
CHANNEL
1
N
Y
0x42000800
7
2
N
13: CORE
12: SLOW
2
N
Y
SERCOM1
0x42000C00
8
3
N
14: CORE
12: SLOW
3
N
Y
SERCOM2
0x42001000
9
4
N
15: CORE
12: SLOW
4
N
Y
5
2
Y
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Table 11-1. Peripherals Configuration Overview
AHB Clock
APB Clock
Peripheral
Name
Base
Address
IRQ
Line
SERCOM3
0x42001400
10
5
SERCOM4
0x42001800
11
SERCOM5
0x42001C00
TC0
PAC
Events
Index
Index
Prot at
Reset
N
16: CORE
12: SLOW
5
N
Y
6
N
17: CORE
12: SLOW
6
N
Y
12
7
N
18: CORE
12: SLOW
7
N
Y
0x42002000
13
8
N
19
8
N
0: TC
28: OVF
29-30: MC0-1
Y
TC1
0x42002400
14
9
N
19
9
N
1: TC
31: OVF
32-33: MC0-1
Y
TC2
0x42002800
15
10
N
20
10
N
2: TC
34: OVF
35-36: MC0-1
Y
TC3
0x42002C00
16
11
N
20
11
N
3: TC
37: OVF
38-39: MC0-1
Y
TC4
0x42003000
17
12
N
21
12
N
4: TC
40: OVF
41-42: MC0-1
Y
TC5
0x42003400
18
13
N
21
13
N
5: TC
43: OVF
44-45: MC0-1
Y
TC6
0x42003800
19
14
N
22
14
N
6: TC
46: OVF
47-48: MC0-1
Y
TC7
0x42003C00
20
15
N
22
15
N
7: TC
49: OVF
50-51: MC0-1
Y
ADC
0x42004000
21
16
Y
23
16
N
8: START
9: SYNC
52: RESRDY
53: WINMON
Y
AC
0x42004400
22
17
N
24: DIG
25: ANA
17
N
10-11: COMP0-1
54-55: COMP0-1
56: WIN0
Y
DAC
0x42004800
23
18
N
26
18
N
12: START
57: EMPTY
Y
13: STCONV
58: EOC
59: WCOMP
PTC
0x42004C00
24
Enabled
Enabled
Index at Reset Index at Reset
Generic
Clock
19
N
27
19
N
User
Generator
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12.
DSU – Device Service Unit
12.1
Overview
The Device Service Unit (DSU) provides a means to detect debugger probes. This enables the ARM Debug Access Port
(DAP) to have control over multiplexed debug pads and CPU reset. The DSU also provides system-level services to
debug adapters in an ARM debug system. It implements a CoreSight Debug ROM that provides device identification as
well as identification of other debug components in the system. Hence, it complies with the ARM Peripheral Identification
specification. The DSU also provides system services to applications that need memory testing, as required for
IEC60730 Class B compliance, for example. The DSU can be accessed simultaneously by a debugger and the CPU, as
it is connected on the High-Speed Bus Matrix. For security reasons, some of the DSU features will be limited or
unavailable when the device is protected by the NVMCTRL security bit (refer to “Security Bit” on page 271).
12.2
Features
z CPU reset extension
z Debugger probe detection (Cold- and Hot-Plugging)
z Chip-Erase command and status
z 32-bit cyclic redundancy check (CRC32) of any memory accessible through the bus matrix
z ARM® CoreSight™ compliant device identification
z Two debug communications channels
z Debug access port security filter
z Onboard memory built-in self-test (MBIST)
12.3
Block Diagram
Figure 12-1. DSU Bock Diagram
DSU
debugger_present
RESET
SWCLK
DEBUGGER PROBE
INTERFACE
cpu_reset_extension
CPU
DAP
AHB-AP
DAP SECURITY FILTER
NVMCTRL
DBG
CORESIGHT ROM
PORTMUX
M
S
CRC-32
SWDIO
MBIST
M
HIGH-SPEED
HIGH-SPEE
BUS
US MATRIX
M
MATR
CHIP ERASE
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12.4
Signal Description
Signal Name
Type
Description
RESET
Digital Input
External reset
SWCLK
Digital Input
SW clock
SWDIO
Digital I/O
SW bidirectional data pin
Refer to “I/O Multiplexing and Considerations” on page 16 for details on the pin mapping for this peripheral.
12.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
12.5.1 I/O Lines
The SWCLK pin is by default assigned to the DSU module to allow debugger probe detection and the condition to stretch
the CPU reset phase. For more information, refer to “Debugger Probe Detection” on page 45. The Hot-Plugging feature
depends on the PORT configuration. If the SWCLK pin function is changed in the PORT or if the PORT_MUX is disabled,
the Hot-Plugging feature is disabled until a power-reset or an external reset.
12.5.2 Power Management
The DSU will continue to operate in any sleep mode where the selected source clock is running.
Refer to “PM – Power Manager” on page 107 for details on the different sleep modes.
12.5.3 Clocks
The DSU bus clocks (CLK_DSU_APB and CLK_DSU_AHB) can be enabled and disabled in the Power Manager. For
more information on the CLK_DSU_APB and CLK_DSU_AHB clock masks, refer to “PM – Power Manager” on page
107.
12.5.4 Interrupts
Not applicable.
12.5.5 Events
Not applicable.
12.5.6 Register Access Protection
All registers with write access are optionally write-protected by the Peripheral Access Controller (PAC), except the
following registers:
z
Debug Communication Channel 0 register (DCC0)
z
Debug Communication Channel 1 register (DCC1)
Write-protection is denoted by the Write-Protection property in the register description.
Write-protection does not apply for accesses through an external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
12.5.7 Analog Connections
Not applicable.
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12.6
Debug Operation
12.6.1 Principle of Operation
The DSU provides basic services to allow on-chip debug using the ARM Debug Access Port and the ARM processor
debug resources:
z
CPU reset extension
z
Debugger probe detection
For more details on the ARM debug components, refer to the ARM Debug Interface v5Architecture Specification.
12.6.2 CPU Reset Extension
“CPU reset extension” refers to the extension of the reset phase of the CPU core after the external reset is released. This
ensures that the CPU is not executing code at startup while a debugger connects to the system. It is detected on a
RESET release event when SWCLK is low. At startup, SWCLK is internally pulled up to avoid false detection of a
debugger if SWCLK is left unconnected. When the CPU is held in the reset extension phase, the CPU Reset Extension
bit (CRSTEXT) of the Status A register (STATUSA.CRSTEXT) is set. To release the CPU, write a one to
STATUSA.CRSTEXT. STATUSA.CRSTEXT will then be set to zero. Writing a zero to STATUSA.CRSTEXT has no
effect. For security reasons, it is not possible to release the CPU reset extension when the device is protected by the
NVMCTRL security bit (refer to “Security Bit” on page 271). Trying to do so sets the Protection Error bit (PERR) of the
Status A register (STATUSA.PERR).
Figure 12-2. Typical CPU Reset Extension Set and Clear Timing Diagram
SWCLK
RESET
DSU CRSTEXT
Clear
CPU reset
extension
CPU_STATE
reset
running
12.6.3 Debugger Probe Detection
12.6.3.1 Cold-Plugging
Cold-Plugging is the detection of a debugger when the system is in reset. Cold-Plugging is detected when the CPU reset
extension is requested, as described above.
12.6.3.2 Hot-Plugging
Hot-Plugging is the detection of a debugger probe when the system is not in reset. Hot-Plugging is not possible under
reset because the detector is reset when POR or RESET are asserted. Hot-Plugging is active when a SWCLK falling
edge is detected. The SWCLK pad is multiplexed with other functions and the user must ensure that its default function is
assigned to the debug system. If the SWCLK function is changed, the Hot-Plugging feature is disabled until a powerreset or external reset occurs. Availability of the Hot-Plugging feature can be read from the Hot-Plugging Enable bit of the
Status B register (STATUSB.HPE).
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Figure 12-3. Hot-Plugging Detection Timing Diagram
SWCLK
RESET
CPU_STATE
reset
running
Hot-Plugging
The presence of a debugger probe is detected when either Hot-Plugging or Cold-Plugging is detected. Once detected,
the Debugger Present bit of the Status B register (STATUSB.DBGPRES) is set. For security reasons, Hot-Plugging is not
available when the device is protected by the NVMCTRL security bit (refer to “Security Bit” on page 271).
This detection requires that pads are correctly powered. Thus, at cold startup, this detection cannot be done until POR is
released. If the device is protected, Cold-Plugging is the only way to detect a debugger probe, and so the external reset
timing must be longer than the POR timing. If external reset is deasserted before POR release, the user must retry the
procedure above until it gets connected to the device.
12.7
Chip-Erase
Chip-Erase consists of removing all sensitive information stored in the chip and clearing the NVMCTRL security bit (refer
to “Security Bit” on page 271). Hence, all volatile memories and the flash array (including the EEPROM emulation area)
will be erased. The flash auxiliary rows, including the user row, will not be erased. When the device is protected, the
debugger must reset the device in order to be detected. This ensures that internal registers are reset after the protected
state is removed. The Chip-Erase operation is triggered by writing a one to the Chip-Erase bit in the Control register
(CTRL.CE). This command will be discarded if the DSU is protected by the Peripheral Access Controller (PAC). Once
issued, the module clears volatile memories prior to erasing the flash array. To ensure that the Chip-Erase operation is
completed, check the Done bit of the Status A register (STATUSA.DONE). The Chip-Erase operation depends on clocks
and power management features that can be altered by the CPU. For that reason, it is recommended to issue a ChipErase after a Cold-Plugging procedure to ensure that the device is in a known and safe state.
The recommended sequence is as follows:
1.
2.
12.8
Issue the Cold-Plugging procedure (refer to “Cold-Plugging” on page 45). The device then:
1.
Detects the debugger probe
2.
Holds the CPU in reset
Issue the Chip-Erase command by writing a one to CTRL.CE. The device then:
1.
Clears the system volatile memories
2.
Erases the whole flash array (including the EEPROM emulation area, not including auxiliary rows)
3.
Erases the lock row, removing the NVMCTRL security bit protection
3.
Check for completion by polling STATUSA.DONE (read as one when completed).
4.
Reset the device to let the NVMCTRL update fuses.
Programming
Programming of the flash or RAM memories is available when the device is not protected by the NVMCTRL security bit
(refer to “Security Bit” on page 271).
1.
At power up, RESET is driven low by a debugger. The on-chip regulator holds the system in a POR state until the
input supply is above the POR threshold (refer to “Power-On Reset (POR) Characteristics” on page 583). The sys-
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tem continues to be held in this static state until the internally regulated supplies have reached a safe operating
state.
12.9
2.
The PM starts, clocks are switched to the slow clock (Core Clock, System Clock, Flash Clock and any Bus Clocks
that do not have clock gate control). Internal resets are maintained due to the external reset.
3.
The debugger maintains a low level on SWCLK. Releasing RESET results in a debugger Cold-Plugging
procedure.
4.
The debugger generates a clock signal on the SWCLK pin, the Debug Access Port (DAP) receives a clock.
5.
The CPU remains in reset due to the Cold-Plugging procedure; meanwhile, the rest of the system is released.
6.
A Chip-Erase is issued to ensure that the flash is fully erased prior to programming.
7.
Programming is available through the AHB-AP.
8.
After operation is completed, the chip can be restarted either by asserting RESET, toggling power or writing a one
to the Status A register CPU Reset Phase Extension bit (STATUSA.CRSTEXT). Make sure that the SWCLK pin is
high when releasing RESET to prevent extending the CPU reset.
Intellectual Property Protection
Intellectual property protection consists of restricting access to internal memories from external tools when the device is
protected, and is accomplished by setting the NVMCTRL security bit (refer to “Security Bit” on page 271). This protected
state can be removed by issuing a Chip-Erase (refer to “Chip-Erase” on page 46). When the device is protected,
read/write accesses using the AHB-AP are limited to the DSU address range and DSU commands are restricted.
The DSU implements a security filter that monitors the AHB transactions generated by the ARM AHB-AP inside the DAP.
If the device is protected, then AHB-AP read/write accesses outside the DSU external address range are discarded,
causing an error response that sets the ARM AHB-AP sticky error bits (refer to the ARM Debug Interface v5 Architecture
Specification on http://www.arm.com).
The DSU is intended to be accessed either:
z
Internally from the CPU, without any limitation, even when the device is protected
z
Externally from a debug adapter, with some restrictions when the device is protected
For security reasons, DSU features have limitations when used from a debug adapter. To differentiate external accesses
from internal ones, the first 0x100 bytes of the DSU register map have been replicated at offset 0x100:
z
The first 0x100 bytes form the internal address range
z
The next 0x100 bytes form the external address range
When the device is protected, the DAP can only issue MEM-AP accesses in the DSU address range limited to the 0x1000x2000 offset range.
The DSU operating registers are located in the 0x00-0xFF area and remapped in 0x100-0x1FF to differentiate accesses
coming from a debugger and the CPU. If the device is protected and an access is issued in the region 0x100-0x1FF, it is
subject to security restrictions. For more information, refer to Table 12-1.
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Figure 12-4. APB Memory Mapping
0x0000
DSU operating
registers
0x00FC
0x0100
0x01FD
Internal address range
(cannot be accessed from debug tools when the device is
protected by the NVMCTRL security bit)
Replicated
DSU operating
registers
Empty
External address range
(can be accessed from debug tools with some restrictions)
0x1000
DSU CoreSight
ROM
0x1FFC
Some features not activated by APB transactions are not available when the device is protected:
Table 12-1. Feature Availability Under Protection
Features
Availability When the Device is Protected
CPU reset extension
Yes
Debugger Cold-Plugging
Yes
Debugger Hot-Plugging
No
12.10 Device Identification
Device identification relies on the ARM CoreSight component identification scheme, which allows the chip to be identified
as an ATMEL device implementing a DSU. The DSU contains identification registers to differentiate the device.
12.10.1 CoreSight Identification
A system-level ARM CoreSight ROM table is present in the device to identify the vendor and the chip identification
method. Its address is provided in the MEM-AP BASE register inside the ARM Debug Access Port. The CoreSight ROM
implements a 64-bit conceptual ID composed as follows from the PID0 to PID7 CoreSight ROM Table registers:
Figure 12-5. Conceptual 64-Bit Peripheral ID
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Table 12-2. Conceptual 64-Bit Peripheral ID Bit Descriptions
Field
Size
JEP-106 CC code
4
Atmel continuation code: 0x0
JEP-106 ID code
7
Atmel device ID: 0x1F
4KB count
4
Indicates that the CoreSight component is a ROM: 0x0
PID4
RevAnd
4
Not used; read as 0
PID3
CUSMOD
4
Not used; read as 0
PID3
PARTNUM
12
Contains 0xCD0 to indicate that DSU is present
4
DSU revision (starts at 0x0 and increments by 1 at both major and minor
revisions). Identifies DSU identification method variants. If 0x0, this
indicates that device identification can be completed by reading the
Device Identification register (DID)
REVISION
Description
Location
PID4
PID1+PID2
PID0+PID1
PID3
For more information, refer to the ARM Debug Interface Version 5 Architecture Specification.
12.10.2 DSU Chip Identification Method:
The DSU DID register identifies the device by implementing the following information:
z
Processor identification
z
Product family identification
z
Product series identification
z
Device select
12.11 Functional Description
12.11.1 Principle of Operation
The DSU provides memory services such as CRC32 or MBIST that require almost the same interface. Hence, the
Address, Length and Data registers are shared. They must be configured first; then a command can be issued by writing
the Control register. When a command is ongoing, other commands are discarded until the current operation is
completed. Hence, the user must wait for the STATUSA.DONE bit to be set prior to issuing another one.
12.11.2 Basic Operation
12.11.2.1 Initialization
The module is enabled by enabling its clocks. For more details, refer to “Clocks” on page 44. The DSU registers can be
write-protected. Refer to “PAC – Peripheral Access Controller” on page 34.
12.11.2.2 Operation from a debug adapter
Debug adapters should access the DSU registers in the external address range 0x100 – 0x2000. If the device is
protected by the NVMCTRL security bit (refer to “Security Bit” on page 271), accessing the first 0x100 bytes causes the
system to return an error (refer to “Intellectual Property Protection” on page 47).
12.11.2.3 Operation from the CPU
There are no restrictions when accessing DSU registers from the CPU. However, the user should access DSU registers
in the internal address range (0x0 – 0x100) to avoid external security restrictions (refer to “Intellectual Property
Protection” on page 47).
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12.11.3 32-bit Cyclic Redundancy Check (CRC32)
The DSU unit provides support for calculating a cyclic redundancy check (CRC32) value for a memory area (including
flash and AHB RAM).
When the CRC32 command is issued from:
z
The internal range, the CRC32 can be operated at any memory location
z
The external range, the CRC32 operation is restricted; DATA, ADDR and LENGTH values are forced (see below)
Table 12-3. AMOD Bit Descriptions when Operating CRC32
AMOD[1:0]
Short Name
0
ARRAY
1
EEPROM
2-3
Reserved
External Range Restrictions
CRC32 is restricted to the full flash array area (EEPROM emulation area not included)
DATA forced to 0xFFFFFFFF before calculation (no seed)
CRC32 of the whole EEPROM emulation area
DATA forced to 0xFFFFFFFF before calculation (no seed)
The algorithm employed is the industry standard CRC32 algorithm using the generator polynomial 0xEDB88320
(reversed representation).
12.11.3.1 Starting CRC32 Calculation
CRC32 calculation for a memory range is started after writing the start address into the Address register (ADDR) and the
size of the memory range into the Length register (LENGTH). Both must be word-aligned.
The initial value used for the CRC32 calculation must be written to the Data register. This value will usually be
0xFFFFFFFF, but can be, for example, the result of a previous CRC32 calculation if generating a common CRC32 of
separate memory blocks.
Once completed, the calculated CRC32 value can be read out of the Data register. The read value must be
complemented to match standard CRC32 implementations or kept non-inverted if used as starting point for subsequent
CRC32 calculations.
If the device is in protected state by the NVMCTRL security bit (refer to “Security Bit” on page 271), it is only possible to
calculate the CRC32 of the whole flash array when operated from the external address space. In most cases, this area
will be the entire onboard non-volatile memory. The Address, Length and Data registers will be forced to predefined
values once the CRC32 operation is started, and values written by the user are ignored. This allows the user to verify the
contents of a protected device.
The actual test is started by writing a one in the 32-bit Cyclic Redundancy Check bit of the Control register (CTRL.CRC).
A running CRC32 operation can be canceled by resetting the module (writing a one to CTRL.SWRST).
12.11.3.2 Interpreting the Results
The user should monitor the Status A register. When the operation is completed, STATUSA.DONE is set. Then the Bus
Error bit of the Status A register (STATUSA.BERR) must be read to ensure that no bus error occurred.
12.11.4 Debug Communication Channels
The Debug Communication Channels (DCCO and DCC1) consist of a pair of registers with associated handshake logic,
accessible by both CPU and debugger even if the device is protected by the NVMCTRL security bit (refer to “Security Bit”
on page 271). The registers can be used to exchange data between the CPU and the debugger, during run time as well
as in debug mode. This enables the user to build a custom debug protocol using only these registers. The DCC0 and
DCC1 registers are accessible when the protected state is active. When the device is protected, however, it is not
possible to connect a debugger while the CPU is running (STATUSA.CRSTEXT is not writable and the CPU is held
under reset). Dirty bits in the status registers indicate whether a new value has been written in DCC0 or DCC1. These
bits,DCC0D and DCC1D, are located in the STATUSB registers. They are automatically set on write and cleared on
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read. The DCC0 and DCC1 registers are shared with the onboard memory testing logic (MBIST). Accordingly, DCC0 and
DCC1 must not be used while performing MBIST operations.
12.11.5 Testing of Onboard Memories (MBIST)
The DSU implements a feature for automatic testing of memory also known as MBIST. This is primarily intended for
production test of onboard memories. MBIST cannot be operated from the external address range when the device is
protected by the NVMCTRL security bit (refer to “Security Bit” on page 271). If a MBIST command is issued when the
device is protected, a protection error is reported in the Protection Error bit in the Status A register (STATUSA.PERR).
1.
Algorithm
The algorithm used for testing is a type of March algorithm called "March LR". This algorithm is able to detect a
wide range of memory defects, while still keeping a linear run time. The algorithm is:
1.
Write entire memory to 0, in any order.
2.
Bit for bit read 0, write 1, in descending order.
3.
Bit for bit read 1, write 0, read 0, write 1, in ascending order.
4.
Bit for bit read 1, write 0, in ascending order.
5.
Bit for bit read 0, write 1, read 1, write 0, in ascending order.
6.
Read 0 from entire memory, in ascending order.
The specific implementation used has a run time of O(14n) where n is the number of bits in the RAM. The detected
faults are:
2.
z
Address decoder faults
z
Stuck-at faults
z
Transition faults
z
Coupling faults
z
Linked Coupling faults
z
Stuck-open faults
Starting MBIST
To test a memory, you need to write the start address of the memory to the ADDR.ADDR bit group, and the size of
the memory into the Length register. See “Physical Memory Map” on page 25 to know which memories are available, and which address they are at.
For best test coverage, an entire physical memory block should be tested at once. It is possible to test only a subset of a memory, but the test coverage will then be somewhat lower.
The actual test is started by writing a one to CTRL.MBIST. A running MBIST operation can be canceled by writing
a one to CTRL.SWRST.
3.
Interpreting the Results
The tester should monitor the STATUSA register. When the operation is completed, STATUSA.DONE is set.
There are two different modes:
z
ADDR.AMOD=0: exit-on-error (default)
In this mode, the algorithm terminates either when a fault is detected or on successful completion. In both cases,
STATUSA.DONE is set. If an error was detected, STATUSA.FAIL will be set. User then can read the DATA and
ADDR registers to locate the fault. Refer to “Locating Errors” on page 51.
z
ADDR.AMOD=1: pause-on-error
In this mode, the MBIST algorithm is paused when an error is detected. In such a situation, only STATUSA.FAIL is
asserted. The state machine waits for user to clear STATUSA.FAIL by writing a one in STATUSA.FAIL to resume.
Prior to resuming, user can read the DATA and ADDR registers to locate the fault. Refer to “Locating Errors” on
page 51.
4.
Locating Errors
If the test stops with STATUSA.FAIL set, one or more bits failed the test. The test stops at the first detected error.
The position of the failing bit can be found by reading the following registers:
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z
ADDR: Address of the word containing the failing bit.
z
DATA: contains data to identify which bit failed, and during which phase of the test it failed. The DATA
register will in this case contains the following bit groups:
Table 12-4. DATA bits Description When MBIST Operation Returns An Error
Bit
31
30
29
28
27
26
25
24
Bit
23
22
21
20
19
18
17
16
Bit
15
14
13
12
11
10
9
8
phase
Bit
7
6
5
4
3
2
1
0
bit_index
z
bit_index: contains the bit number of the failing bit
z
phase: indicates which phase of the test failed and the cause of the error. See Table 12-5 on page 52.
Table 12-5. MBIST Operation Phases
Phase
Test Actions
0
Write all bits to zero. This phase cannot fail.
1
Read 0, write 1, increment address
2
Read 1, write 0
3
Read 0, write 1, decrement address
4
Read 1, write 0, decrement address
5
Read 0, write 1
6
Read 1, write 0, decrement address
7
Read all zeros. bit_index is not used
12.11.6 System Services Availability When Accessed Externally
External access: Access performed in the DSU address offset 0x200-0x1FFF range.
Internal access: Access performed in the DSU address offset 0x0-0x100 range.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
52
Table 12-6. Available Features When Operated From The External Address Range and Device is Protected
Features
Chip-Erase command and status
CRC32
Availability From The External Address Range and Device is Protected
Yes
Yes, only full array or full EEPROM
CoreSight Compliant Device identification
Yes
Debug communication channels
Yes
Testing of onboard memories (MBIST)
Yes
STATUSA.CRSTEXT clearing
No (STATUSA.PERR is set when attempting to do so)
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
53
12.12 Register Summary
Table 12-7. Register Summary
Offset
Name
Bit
Pos
0x0000
CTRL
7:0
CE
MBIST
CRC
0x0001
STATUSA
7:0
PERR
FAIL
BERR
CRSTEXT
DONE
0x0002
STATUSB
7:0
HPE
DCCD1
DCCD0
DBGPRES
PROT
0x0003
Reserved
0x0004
7:0
0x0005
SWRST
ADDR[5:0]
AMOD[1:0]
15:8
ADDR[13:6]
0x0006
23:16
ADDR[21:14]
0x0007
31:24
ADDR[29:22]
0x0008
7:0
ADDR
0x0009
LENGTH[5:0]
15:8
LENGTH[13:6]
0x000A
23:16
LENGTH[21:14]
0x000B
31:24
LENGTH[29:22]
0x000C
7:0
DATA[7:0]
15:8
DATA[15:8]
0x000E
23:16
DATA[23:16]
0x000F
31:24
DATA[31:24]
0x0010
7:0
DATA[7:0]
15:8
DATA[15:8]
0x0012
23:16
DATA[23:16]
0x0013
31:24
DATA[31:24]
0x0014
7:0
DATA[7:0]
15:8
DATA[15:8]
0x0016
23:16
DATA[23:16]
0x0017
31:24
DATA[31:24]
0x0018
7:0
DEVSEL[7:0]
LENGTH
0x000D
DATA
0x0011
DCC0
0x0015
DCC1
0x0019
15:8
DIE[3:0]
REVISION[3:0]
DID
0x001A
23:16
0x001C
31:24
0x001D
Reserved
...
...
0x00FF
Reserved
FAMILY[0]
SERIES[5:0]
PROCESSOR[3:0]
FAMILY[4:1]
External address range:
0x01000x01FF
Replicates the 0x00:0x1C address range,
Gives access to the same resources but with security restrictions when the device is protected.
This address range is the only one accessible externally (using the ARM DAP) when the device is protected.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
54
0x1000
7:0
0x1001
15:8
FMT
EPRES
FMT
EPRES
ADDOFF[3:0]
ENTRY0
0x1002
23:16
ADDOFF[11:4]
0x1003
31:24
ADDOFF[19:12]
0x1004
7:0
0x1005
15:8
ADDOFF[3:0]
ENTRY1
0x1006
23:16
ADDOFF[11:4]
0x1007
31:24
ADDOFF[19:12]
0x1008
7:0
END[7:0]
15:8
END[15:8]
0x100A
23:16
END[23:16]
0x100B
31:24
END[31:24]
0x1FCC
7:0
0x1009
END
0x1FCD
SMEMP
15:8
MEMTYPE
0x1FCE
23:16
0x1FCF
31:24
0x1FD0
7:0
0x1FD1
FKBC[3:0]
JEPCC[3:0]
15:8
PID4
0x1FD2
23:16
0x1FD3
31:24
0x1FD4
Reserved
…
…
0x1FDF
Reserved
0x1FE0
7:0
0x1FE1
PARTNBL[7:0]
15:8
PID0
0x1FE2
23:16
0x1FE3
31:24
0x1FE4
7:0
0x1FE5
JEPIDCL[3:0]
PARTNBH[3:0]
15:8
PID1
0x1FE6
23:16
0x1FE7
31:24
0x1FE8
7:0
0x1FE9
REVISION[3:0]
JEPU
JEPIDCH[2:0]
15:8
PID2
0x1FEA
23:16
0x1FEB
31:24
0x1FEC
7:0
0x1FED
REVAND[3:0]
CUSMOD[3:0]
15:8
PID3
0x1FEE
23:16
0x1FEF
31:24
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
55
0x1FF0
7:0
0x1FF1
PREAMBLEB0[7:0]
15:8
CID0
0x1FF2
23:16
0x1FF3
31:24
0x1FF4
7:0
0x1FF5
CCLASS[3:0]
PREAMBLE[3:0]
15:8
CID1
0x1FF6
23:16
0x1FF7
31:24
0x1FF8
7:0
0x1FF9
PREAMBLEB2[7:0]
15:8
CID2
0x1FFA
23:16
0x1FFB
31:24
0x1FFC
7:0
0x1FFD
PREAMBLEB3[7:0]
15:8
CID3
0x1FFE
23:16
0x1FFF
31:24
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
56
12.13 Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write protection is denoted by
the Write-Protected property in each individual register description. Refer to “Register Access Protection” on page 44 for
details.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
57
12.13.1 Control
Name:
CTRL
Offset:
0x0000
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
CE
MBIST
CRC
1
0
SWRST
Access
R
R
R
W
W
W
R
W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 4 – CE: Chip Erase
Writing a zero to this bit has no effect.
Writing a one to this bit starts the Chip-Erase operation.
z
Bit 3 – MBIST: Memory Built-In Self-Test
Writing a zero to this bit has no effect.
Writing a one to this bit starts the memory BIST algorithm.
z
Bit 2 – CRC: 32-bit Cyclic Redundancy Check
Writing a zero to this bit has no effect.
Writing a one to this bit starts the cyclic redundancy check algorithm.
z
Bit 1 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written.
z
Bit 0 – SWRST: Software Reset
Writing a zero to this bit has no effect.
Writing a one to this bit resets the module.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
58
12.13.2 Status A
Name:
STATUSA
Offset:
0x0001
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
PERR
FAIL
BERR
CRSTEXT
DONE
Access
R
R
R
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 4 – PERR: Protection Error
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Protection Error bit.
This bit is set when a command that is not allowed in protected state is issued.
z
Bit 3 – FAIL: Failure
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Failure bit.
This bit is set when a DSU operation failure is detected.
z
Bit 2 – BERR: Bus Error
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Bus Error bit.
This bit is set when a bus error is detected.
z
Bit 1 – CRSTEXT: CPU Reset Phase Extension
Writing a zero to this bit has no effect.
Writing a one to this bit clears the CPU Reset Phase Extension bit.
This bit is set when a debug adapter Cold-Plugging is detected, which extends the CPU reset phase.
z
Bit 0 – DONE: Done
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Done bit.
This bit is set when a DSU operation is completed.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
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12.13.3 Status B
Name:
STATUSB
Offset:
0x0002
Reset:
0x1X
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
HPE
DCCD1
DCCD0
DBGPRES
PROT
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
1
0
0
X
X
z
Bits 7:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 4 – HPE: Hot-Plugging Enable
Writing a zero to this bit has no effect.
Writing a one to this bit has no effect.
This bit is set when Hot-Plugging is enabled.
This bit is cleared when Hot-Plugging is disabled. This is the case when the SWCLK function is changed. Only a
power-reset or a external reset can set it again.
z
Bits 3:2 – DCCDx [x=1..0]: Debug Communication Channel x Dirty
Writing a zero to this bit has no effect.
Writing a one to this bit has no effect.
This bit is set when DCCx is written.
This bit is cleared when DCCx is read.
z
Bit 1 – DBGPRES: Debugger Present
Writing a zero to this bit has no effect.
Writing a one to this bit has no effect.
This bit is set when a debugger probe is detected.
This bit is never cleared.
z
Bit 0 – PROT: Protected
Writing a zero to this bit has no effect.
Writing a one to this bit has no effect.
This bit is set at powerup when the device is protected.
This bit is never cleared.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
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12.13.4 Address
Name:
ADDR
Offset:
0x0004
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
ADDR[29:22]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
ADDR[21:14]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
ADDR[13:6]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ADDR[5:0]
Access
AMOD[1:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Reset
z
Bits 31:2 – ADDR[29:0]: Address
Initial word start address needed for memory operations.
z
Bits 1:0 – AMOD[1:0]:
z
AMOD bit descriptions when operating CRC32: refer to description in section “32-bit Cyclic Redundancy
Check (CRC32)”
z
AMOD bit descriptions when Testing of Onboard Memories (MBIST): refer to description in section “Testing
of Onboard Memories (MBIST)”.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
61
12.13.5 Length
Name:
LENGTH
Offset:
0x0008
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
LENGTH[29:22]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
LENGTH[21:14]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
LENGTH[13:6]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
LENGTH[5:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R
R
0
0
0
0
0
0
0
0
z
Bits 31:2 – LENGTH[29:0]: Length
Length in words needed for memory operations.
z
Bits 1:0 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
Atmel | SMART SAM D20 [DATASHEET]
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62
12.13.6 Data
Name:
DATA
Offset:
0x000C
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
DATA[31:24]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
DATA[23:16]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
DATA[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DATA[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31:0 – DATA[31:0]: Data
Memory operation initial value or result value.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
63
12.13.7 Debug Communication Channel n
Name:
DCCn
Offset:
0x0010+n*0x4 [n=0..1]
Reset:
0x00000000
Property:
-
Bit
31
30
29
28
27
26
25
24
DATA[31:24]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
DATA[23:16]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
DATA[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DATA[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31:0 – DATA[31:0]: Data
Data register.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
64
12.13.8 Device Identification
Name:
DID
Offset:
0x0018
Reset:
0x1000XXXX
Property:
Write-Protected
Bit
31
30
29
28
27
26
PROCESSOR[3:0]
25
24
FAMILY[4:1]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
FAMILY[0]
SERIES[5:0]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
DIE[3:0]
REVISION[3:0]
Access
R
R
R
R
R
R
R
R
Reset
X
X
X
X
X
X
X
X
Bit
7
6
5
4
3
2
1
0
DEVSEL[7:0]
Access
R
R
R
R
R
R
R
R
Reset
X
X
X
X
X
X
X
X
The information in this register is related to the ordering code. Refer to the “Ordering Information” on page 4 for details.
z
Bits 31:28 – PROCESSOR[3:0]: Processor
The value of this field defines the processor used on the device. For this device, the value of this field is 0x1, corresponding to the ARM Cortex-M0+ processor.
z
Bits 27:23 – FAMILY[4:0]: Product Family
The value of this field corresponds to the Product Family part of the ordering code. For this device, the value of this
field is 0x0, corresponding to the SAM D family of base line microcontrollers.
z
Bits 21:16 – SERIES[5:0]: Product Series
The value of this field corresponds to the Product Series part of the ordering code. For this device, the value of this
field is 0x00, corresponding to a product with the Cortex-M0+ processor and a basic feature set.
z
Bits 15:12 – DIE[3:0]: Die Identification
Identifies the die in the family.
z
Bits 11:8 – REVISION[3:0]: Revision
Identifies the die revision number.
z
Bits 7:0 – DEVSEL[7:0]: Device Selection
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
65
DEVSEL is used to identify a device within a product family and product series. The value corresponds to the
Flash memory density, pin count and device variant parts of the ordering code. Refer to Table 12-8. for details.
Table 12-8. Device Selection
DEVSEL
Device
Flash
RAM
Pincount
0x0
SAMD20J18A
256KB
32KB
64
0x1
SAMD20J17A
128KB
16KB
64
0x2
SAMD20J16A
64KB
8KB
64
0x3
SAMD20J15A
32KB
4KB
64
0x4
SAMD20J14A
16KB
2KB
64
0x5
SAMD20G18A
256KB
32KB
48
0x6
SAMD20G17A
128KB
16KB
48
0x7
SAMD20G16A
64KB
8KB
48
0x8
SAMD20G15A
32KB
4KB
48
0x9
SAMD20G14A
16KB
2KB
48
0xA
SAMD20E18A
256KB
32KB
32
0xB
SAMD20E17A
128KB
16KB
32
0xC
SAMD20E16A
64KB
8KB
32
0xD
SAMD20E15A
32KB
4KB
32
0xE
SAMD20E14A
16KB
2KB
32
0xF-0xFF
Reserved
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
66
12.13.9 CoreSight ROM Table Entry n
Name:
ENTRYn
Offset:
0x1000+n*0x4 [n=0..1]
Reset:
0xXXXXX00X
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
ADDOFF[19:12]
Access
R
R
R
R
R
R
R
R
Reset
X
X
X
X
X
X
X
X
Bit
23
22
21
20
19
18
17
16
ADDOFF[11:4]
Access
R
R
R
R
R
R
R
R
Reset
X
X
X
X
X
X
X
X
Bit
15
14
13
12
11
10
9
8
ADDOFF[3:0]
Access
R
R
R
R
R
R
R
R
Reset
X
X
X
X
0
0
0
0
Bit
7
6
5
4
3
2
1
0
FMT
EPRES
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
1
X
z
Bits 31:12 – ADDOFF[19:0]: Address Offset
The base address of the component, relative to the base address of this ROM table.
z
Bits 11:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – FMT: Format
Always read as one, indicates a 32-bit ROM table.
z
Bit 0 – EPRES: Entry Present
This bit indicates whether an entry is present at this location in the ROM table.
This bit is set at powerup if the device is not protected indicating that the entry is not present.
This bit is cleared at powerup if the device is not protected indicating that the entry is present.
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12.13.10 CoreSight ROM Table End
Name:
END
Offset:
0x1008
Reset:
0x00000000
Property:
-
Bit
31
30
29
28
27
26
25
24
END[31:24]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
END[23:16]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
END[15:8]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
END[7:0]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bits 31:0 – END[31:0]: End Marker
Indicates the end of the CoreSight ROM table entries.
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12.13.11 Coresight ROM Table Memory Type
Name:
MEMTYPE
Offset:
0x1FCC
Reset:
0x0000000X
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
SMEMP
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
X
z
Bits 31:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – SMEMP: System Memory Present
This bit indicates whether system memory is present on the bus that connects to the ROM table.
This bit is set at powerup if the device is not protected indicating that the system memory is accessible from a
debug adapter.
This bit is cleared at powerup if the device is protected indicating that the system memory is not accessible from a
debug adapter.
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12.13.12 Peripheral Identification 4
Name:
PID4
Offset:
0x1FD0
Reset:
0x00000000
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
FKBC[3:0]
JEPCC[3:0]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bits 31:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 7:4 – FKBC[3:0]: 4KB Count
These bits will always return zero when read, indicating that this debug component occupies one 4KB block.
z
Bits 3:0 – JEPCC[3:0]: JEP-106 Continuation Code
These bits will always return zero when read, indicating a Atmel device.
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12.13.13 Peripheral Identification 0
Name:
PID0
Offset:
0x1FE0
Reset:
0x000000D0
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
PARTNBL[7:0]
Access
R
R
R
R
R
R
R
R
Reset
1
1
0
1
0
0
0
0
z
Bits 31:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 7:0 – PARTNBL[7:0]: Part Number Low
These bits will always return 0xD0 when read, indicating that this device implements a DSU module instance.
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12.13.14 Peripheral Identification 1
Name:
PID1
Offset:
0x1FE4
Reset:
0x000000FC
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
JEPIDCL[3:0]
PARTNBH[3:0]
Access
R
R
R
R
R
R
R
R
Reset
1
1
1
1
1
1
0
0
z
Bits 31:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 7:4 – JEPIDCL[3:0]: Low part of the JEP-106 Identity Code
These bits will always return 0xF when read, indicating a Atmel device (Atmel JEP-106 identity code is 0x1F).
z
Bits 3:0 – PARTNBH[3:0]: Part Number High
These bits will always return 0xC when read, indicating that this device implements a DSU module instance.
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12.13.15 Peripheral Identification 2
Name:
PID2
Offset:
0x1FE8
Reset:
0x00000009
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
REVISION[3:0]
JEPU
JEPIDCH[2:0]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
1
0
0
1
z
Bits 31:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 7:4 – REVISION[3:0]: Revision Number
Revision of the peripheral. Starts at 0x0 and increments by one at both major and minor revisions.
z
Bit 3 – JEPU: JEP-106 Identity Code is used
This bit will always return one when read, indicating that JEP-106 code is used.
z
Bits 2:0 – JEPIDCH[2:0]: JEP-106 Identity Code High
These bits will always return 0x1 when read, indicating an Atmel device (Atmel JEP-106 identity code is 0x1F).
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12.13.16 Peripheral Identification 3
Name:
PID3
Offset:
0x1FEC
Reset:
0x00000000
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
REVAND[3:0]
CUSMOD[3:0]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bits 31:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 7:4 – REVAND[3:0]: Revision Number
These bits will always return 0x0 when read.
z
Bits 3:0 – CUSMOD[3:0]: ARM CUSMOD
These bits will always return 0x0 when read.
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12.13.17 Component Identification 0
Name:
CID0
Offset:
0x1FF0
Reset:
0x0000000D
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
PREAMBLEB0[7:0]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
1
1
0
1
z
Bits 31:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 7:0 – PREAMBLEB0[7:0]: Preamble Byte 0
These bits will always return 0xD when read.
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12.13.18 Component Identification 1
Name:
CID1
Offset:
0x1FF4
Reset:
0x00000010
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
CCLASS[3:0]
PREAMBLE[3:0]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
1
0
0
0
0
z
Bits 31:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 7:4 – CCLASS[3:0]: Component Class
These bits will always return 0x1 when read indicating that this ARM CoreSight component is ROM table (refer to
the ARM Debug Interface v5 Architecture Specification at http://www.arm.com).
z
Bits 3:0 – PREAMBLE[3:0]: Preamble
These bits will always return 0x0 when read.
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12.13.19 Component Identification 2
Name:
CID2
Offset:
0x1FF8
Reset:
0x00000005
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
PREAMBLEB2[7:0]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
1
0
1
z
Bits 31:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 7:0 – PREAMBLEB2[7:0]: Preamble Byte 2
These bits will always return 0x05 when read.
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12.13.20 Component Identification 3
Name:
CID3
Offset:
0x1FFC
Reset:
0x000000B1
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
PREAMBLEB3[7:0]
Access
R
R
R
R
R
R
R
R
Reset
1
0
1
1
0
0
0
1
z
Bits 31:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 7:0 – PREAMBLEB3[7:0]: Preamble Byte 3
These bits will always return 0xB1 when read.
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13.
Clock System
This chapter only aims to summarize the clock distribution and terminology in the SAM D20 device. It will not explain
every detail of its configuration. For in-depth documentation, see the referenced module chapters.
13.1
Clock Distribution
Figure 13-1. Clock distribution
PM
SYSCTRL
Main Clock
Controller
GCLK
XOSC
Generic Clock
Generator 0
OSCULP32K
OSC32K
XOSC32K
OSC8M
DFLL48M
Generic Clock
Generator 1
Generic Clock
Generator x
Generic Clock
Multiplexer 0
(DFLL48M Reference)
Generic Clock
Multiplexer 1
Generic Clock
Multiplexer y
Peripheral 0
Generic
Clocks
Peripheral z
AHB/APB System Clocks
The clock system on the SAM D20 consists of:
z
Clock sources, controlled by SYSCTRL
z
z
z
A Clock source is the base clock signal used in the system. Example clock sources are the internal 8MHz
oscillator (OSC8M), External crystal oscillator (XOSC) and the Digital frequency locked loop (DFLL48M).
Generic Clock Controller (GCLK) which controls the clock distribution system, made up of:
z
Generic Clock generators: A programmable prescaler, that can use any of the system clock sources as its
source clock. GCLKGEN[0] also called GCLK_MAIN, is the clock feeding the Power Manager. The Power
Manager generates main clock.
z
Generic Clocks: Typically the clock input of a peripheral on the system. The generic clocks, through the
Generic Clock Multiplexer, can use any of the Generic Clock generators as its clock source. Multiple
instances of a peripheral will typically have a separate generic clock for each instance. The output from
Generic clock multiplexer 0 is used as reference input for DFLL48M. Here DFLL48M should not be used as
a source for Generic Clock Generator x, which feeds the Generic Clock Multiplexer 0.
Power Manager (PM)
z
The PM controls synchronous clocks on the system. This includes the CPU, bus clocks (APB, AHB) as well
as the synchronous (to the CPU) user interfaces of the peripherals. It contains clock masks that can turn
on/off the user interface of a peripheral as well as prescalers for the CPU and bus clocks.
Figure 13-2 shows an example where SERCOM0 is clocked by the DFLL48M in open loop mode. The DFLL48M is
enabled, the Generic Clock Generator 1 uses the DFLL48M as its clock source, and the generic clock 13, also called
GCLK_SERCOM0_CORE, that is connected to SERCOM0 uses generator 1 as its source. The SERCOM0 interface,
clocked by CLK_SERCOM0_APB, has been unmasked in the APBC Mask register in the PM.
Atmel | SMART SAM D20 [DATASHEET]
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Figure 13-2. Example of SERCOM clock
PM
Synchronous Clock
Controller
SYSCTRL
DFLL48M
13.2
CLK_SERCOM0_APB
GCLK
Generic Clock
Generator 1
Generic Clock
Multiplexer 20
GCLK_SERCOM0_CORE
SERCOM 0
Synchronous and Asynchronous Clocks
As the CPU and the peripherals can be clocked from different clock sources, possibly with widely different clock speeds,
some peripheral accesses by the CPU needs to be synchronized between the different clock domains. In these cases the
peripheral includes a SYNCBUSY status flag that can be used to check if a sync operation is in progress. As the nature
of the synchronization might vary between different peripherals, detailed description for each peripheral can be found in
the sub-chapter “synchronization” for each peripheral where this is necessary.
In the datasheet references to synchronous clocks are referring to the CPU and bus clocks, while asynchronous clocks
are clock generated by generic clocks.
13.3
Register Synchronization
13.3.1 Overview
All peripherals are composed of one digital bus interface, which is connected to the APB or AHB bus and clocked using a
corresponding synchronous clock, and one core clock, which is clocked using a generic clock. Access between these
clock domains must be synchronized. As this mechanism is implemented in hardware the synchronization process takes
place even if the clocks domains are clocked from the same source and on the same frequency. All registers in the bus
interface are accessible without synchronization. All core registers in the generic clock domain must be synchronized
when written. Some core registers must be synchronized when read. Registers that need synchronization has this
denoted in each individual register description. Two properties are used: write-synchronization and read-synchronization.
A common synchronizer is used for all registers in one peripheral, as shown in Figure 13-3. Therefore, only one register
per peripheral can be synchronized at a time.
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Figure 13-3. Synchronization
Asynchronous Domain
(generic clock)
Synchronous Domain
(CLK_APB)
Sync
Non Synced reg
Peripheral bus
INTFLAG
Write-Synced reg
SYNCBUSY
STATUS
READREQ
Synchronizer
Write-Synced reg
R/W-Synced reg
13.3.2 Write-Synchronization
The write-synchronization is triggered by a write to any generic clock core register. The Synchronization Busy bit in the
Status register (STATUS.SYNCBUSY) will be set when the write-synchronization starts and cleared when the writesynchronization is complete. Refer to “Synchronization Delay” on page 83 for details on the synchronization delay.
When the write-synchronization is ongoing (STATUS.SYNCBUSY is one), any of the following actions will cause the
peripheral bus to stall until the synchronization is complete:
z
Writing a generic clock core register
z
Reading a read-synchronized core register
z
Reading the register that is being written (and thus triggered the synchronization)
Core registers without read-synchronization will remain static once they have been written and synchronized, and can be
read while the synchronization is ongoing without causing the peripheral bus to stall. APB registers can also be read
while the synchronization is ongoing without causing the peripheral bus to stall.
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13.3.3 Read-Synchronization
Reading a read-synchronized core register will cause the peripheral bus to stall immediately until the readsynchronization is complete. The Synchronization Busy bit in the Status register (STATUS.SYNCBUSY) will be set when
the read-synchronization starts and cleared when the read-synchronization is complete.
Refer to “Synchronization Delay” on page 83 for details on the synchronization delay.
Note that reading a read-synchronized core register while STATUS.SYNCBUSY is one will cause the peripheral bus to
stall twice; first because of the ongoing synchronization, and then again because reading a read-synchronized core
register will cause the peripheral bus to stall immediately.
13.3.4 Completion of synchronization
The user can either poll STATUS.SYNCBUSY or use the Synchronisation Ready interrupt (if available) to check when
the synchronization is complete. It is also possible to perform the next read/write operation and wait, as this next
operation will be started once the previous write/read operation is synchronized and/or complete.
13.3.5 Read Request
The read request functionality is only available to peripherals that have the Read Request register (READREQ)
implemented. Refer to the register description of individual peripheral chapters for details.
To avoid forcing the peripheral bus to stall when reading read-synchronized core registers, the read request mechanism
can be used.
13.3.5.1 Basic Read Request
Writing a one to the Read Request bit in the Read Request register (READREQ.RREQ) will request readsynchronization of the register specified in the Address bits in READREQ (READREQ.ADDR) and set
STATUS.SYNCBUSY. When read-synchronization is complete, STATUS.SYNCBUSY is cleared. The readsynchronized value is then available for reading without delay until READREQ.RREQ is written to one again.
The address to use is the offset to the peripheral's base address of the register that should be synchronized.
13.3.5.2 Continuous Read Request
Writing a one to the Read Continuously bit in READREQ (READREQ.RCONT) will force continuous readsynchronization of the register specified in READREQ.ADDR. The latest value is always available for reading without
stalling the bus, as the synchronization mechanism is continuously synchronizing the given value.
SYNCBUSY is set for the first synchronization, but not for the subsequent synchronizations. If another synchronization is
attempted, i.e. by executing a write-operation of a write-synchronized register, the read request will be stopped, and will
have to be manually restarted.
Note that continuous read-synchronization is paused in sleep modes where the generic clock is not running. This means
that a new read request is required if the value is needed immediately after exiting sleep.
13.3.6 Write-Synchronization of CTRL.ENABLE
Writing to the Enable bit in the Control register (CTRL.ENABLE) will also trigger write-synchronization and set
STATUS.SYNCBUSY. CTRL.ENABLE will read its new value immediately after being written. The Synchronisation
Ready interrupt (if available) cannot be used for Enable write-synchronization.
When the enable write-synchronization is ongoing (STATUS.SYNCBUSY is one), attempt to do any of the following will
cause the peripheral bus to stall until the enable synchronization is complete:
z
Writing a core register
z
Writing an APB register
z
Reading a read-synchronized core register
APB registers can be read while the enable write-synchronization is ongoing without causing the peripheral bus to stall.
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13.3.7 Software Reset Write-Synchronization
Writing a one to the Software Reset bit in CTRL (CTRL.SWRST) will also trigger write-synchronization and set
STATUS.SYNCBUSY. When writing a one to the CTRL.SWRST bit it will immediately read as one. CTRL.SWRST and
STATUS.SYNCBUSY will be cleared by hardware when the peripheral has been reset. Writing a zero to the
CTRL.SWRST bit has no effect. The Synchronisation Ready interrupt (if available) cannot be used for Software Reset
write-synchronization.
When the software reset is in progress (STATUS.SYNCBUSY and CTRL.SWRST are one), attempt to do any of the
following will cause the peripheral bus to stall until the Software Reset synchronization and the reset is complete:
z
Writing a core register
z
Writing an APB register
z
Reading a read-synchronized register
APB registers can be read while the software reset is being write-synchronized without causing the peripheral bus to
stall.
13.3.8 Synchronization Delay
The synchronization will delay the write or read access duration by a delay D, given by the equation:
5 ⋅ P GCLK + 2 ⋅ P APB < D < 6 ⋅ P GCLK + 3 ⋅ P APB
Where P GCLK is the period of the generic clock and P APB is the period of the peripheral bus clock. A normal peripheral
bus register access duration is 2 ⋅ P APB .
13.4
Enabling a Peripheral
To enable a peripheral clocked by a generic clock, the following parts of the system needs to be configured:
13.5
z
A running clock source.
z
A clock from the Generic Clock Generator must be configured to use one of the running clock sources, and the
generator must be enabled.
z
The generic clock, through the Generic Clock Multiplexer, that connects to the peripheral needs to be configured
with a running clock from the Generic Clock Generator, and the generic clock must be enabled.
z
The user interface of the peripheral needs to be unmasked in the PM. If this is not done the peripheral registers will
read as all 0’s and any writes to the peripheral will be discarded.
On-demand, Clock Requests
Figure 13-4. Clock request routing
Clock request
DFLL48M
Generic Clock
Generator
ENABLE
GENEN
RUNSTDBY
RUNSTDBY
Clock request
Generic Clock
Multiplexer
CLKEN
Clock request
Peripheral
ENABLE
RUNSTDBY
ONDEMAND
All the clock sources in the system can be run in an on-demand mode, where the clock source is in a stopped state when
no peripherals are requesting the clock source. Clock requests propagate from the peripheral, via the GCLK, to the clock
source. If one or more peripheral is using a clock source, the clock source will be started/kept running. As soon as the
clock source is no longer needed and no peripheral have an active request the clock source will be stopped until
requested again. For the clock request to reach the clock source, the peripheral, the generic clock and the clock from the
Generic Clock Generator in-between must be enabled. The time taken from a clock request being asserted to the clock
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source being ready is dependent on the clock source startup time, clock source frequency as well as the divider used in
the Generic Clock Generator. The total startup time from a clock request to the clock is available for the peripheral is:
Delay_start_max = Clock source startup time + 2 * clock source periods + 2 * divided clock source periods
Delay_start_min = Clock source startup time + 1 * clock source period + 1 * divided clock source period
The delay for shutting down the clock source when there is no longer an active request is:
Delay_stop_min = 1 * divided clock source period + 1 * clock source period
Delay_stop_max = 2 * divided clock source periods + 2 * clock source periods
The On-Demand principle can be disabled individually for each clock source by clearing the ONDEMAND bit located in
each clock source controller. The clock is always running whatever is the clock request. This has the effect to remove the
clock source startup time at the cost of the power consumption.
In standby mode, the clock request mechanism is still working if the modules are configured to run in standby mode
(RUNSTDBY bit).
13.6
Power Consumption vs Speed
Due to the nature of the asynchronous clocking of the peripherals there are some considerations that needs to be taken
if either targeting a low-power or a fast-acting system. If clocking a peripheral with a very low clock, the active power
consumption of the peripheral will be lower. At the same time the synchronization to the synchronous (CPU) clock
domain is dependent on the peripheral clock speed, and will be longer with a slower peripheral clock; giving lower
response time and more time waiting for the synchronization to complete.
13.7
Clocks after Reset
On any reset the synchronous clocks start to their initial state:
z
OSC8M is enabled and divided by 8
z
GCLK_MAIN uses OSC8M as source
z
CPU and BUS clocks are undivided
On a power reset the GCLK starts to their initial state:
z
z
All generic clock generators disabled except:
z
the generator 0 (GCLK_MAIN) using OSC8M as source, with no division
z
the generator 2 using OSCULP32K as source, with no division
All generic clocks disabled except:
z
the WDT generic clock using the generator 2 as source
On a user reset the GCLK starts to their initial state, except for:
z
generic clocks that are write-locked (WRTLOCK is written to one prior to reset or the WDT generic clock if the
WDT Always-On at power on bit set in the NVM User Row)
z
The generic clock dedicated to the RTC if the RTC generic clock is enabled
On any reset the clock sources are reset to their initial state except the 32KHz clock sources which are reset only by a
power reset.
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14.
GCLK – Generic Clock Controller
14.1
Overview
Several peripherals may require specific clock frequencies to operate correctly. The Generic Clock Controller consists of
number of generic clock generators and generic clock multiplexers that can provide a wide range of clock frequencies.
The generic clock generators can be set to use different external and internal clock sources. The selected clock can be
divided down in the generic clock generator. The outputs from the generic clock generators are used as clock sources for
the generic clock multiplexers, which select one of the sources to generate a generic clock (GCLK_PERIPHERAL), as
shown in Figure 14-2. The number of generic clocks, m, depends on how many peripherals the device has.
14.2
Features
z Provides generic clocks
z Wide frequency range
z Clock source for the generator can be changed on the fly
14.3
Block Diagram
The Generic Clock Controller can be seen in the clocking diagram, which is shown in Figure 14-1 .
Figure 14-1. Device Clocking Diagram
GENERIC CLOCK CONTROLLER
SYSCTRL
Generic Clock Generator
XOSC
OSCULP32K
Generic Clock Multiplexer
OSC32K
GCLK_PERIPHERAL
XOSC32K
OSC8M
DFLL48M
Clock
Divider &
Masker
Clock
Gate
PERIPHERALS
GCLK_IO
GCLK_MAIN
PM
The Generic Clock Controller block diagram is shown in Figure 14-2.
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Figure 14-2. Generic Clock Controller Block Diagram(1)
Generic Clock Generator 0
Clock Sources
Clock
Divider &
Masker
GCLK_IO[0]
(I/O input)
GCLK_MAIN
GCLKGEN[0]
Generic Clock Multiplexer 0
GCLK_PERIPHERAL[0]
Clock
Gate
Generic Clock Generator 1
Generic Clock Multiplexer 1
Clock
Divider &
Masker
GCLK_IO[1]
(I/O input)
GCLK_IO[0]
(I/O output)
GCLK_IO[1]
(I/O output)
GCLKGEN[1]
GCLK_PERIPHERAL[1]
Clock
Gate
Generic Clock Generator n
Clock
Divider &
Masker
GCLK_IO[n]
(I/O input)
GCLK_IO[n]
(I/O output)
GCLKGEN[n]
Generic Clock Multiplexer m
Clock
Gate
GCLK_PERIPHERAL[m]
GCLKGEN[n:0]
Note:
14.4
1.
If the GENCTRL.SRC=GCLKIN the GCLK_IO is set as an input.
Signal Description
Signal Name
Type
GCLK_IO[n:0]
Digital I/O
Description
Source clock when input
Generic clock when output
Refer to “I/O Multiplexing and Considerations” on page 16 for details on the pin mapping for this peripheral. One signal
can be mapped on several pins.
14.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
14.5.1 I/O Lines
Using the Generic Clock Controller’s I/O lines requires the I/O pins to be configured. Refer to “PORT” on page 287 for
details.
14.5.2 Power Management
The Generic Clock Controller can operate in all sleep modes, if required. Refer to Table 15-4 for details on the different
sleep modes.
14.5.3 Clocks
The Generic Clock Controller bus clock (CLK_GCLK_APB) can be enabled and disabled in the Power Manager, and the
default state of CLK_GCLK_APB can be found in the Peripheral Clock Masking section in APBAMASK.
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14.5.4 Interrupts
Not applicable.
14.5.5 Events
Not applicable.
14.5.6 Debug Operation
Not applicable.
14.5.7 Register Access Protection
All registers with write-access are optionally write-protected by the Peripheral Access Controller (PAC).
Write-protection is denoted by the Write-Protection property in the register description.
When the CPU is halted in debug mode or the CPU reset is extended, all write-protection is automatically disabled.
Write-protection does not apply for accesses through an external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
14.5.8 Analog Connections
Not applicable.
14.6
Functional Description
14.6.1 Principle of Operation
The GCLK module is comprised of eight generic clock generators sourcing m generic clock multiplexers.
A clock source selected as input to one of the generic clock generators can be used directly, or it can be prescaled in the
generic clock generator before the generator output is used as input to one or more of the generic clock multiplexers.
A generic clock multiplexer provides a generic clock to a peripheral (GCLK_PERIPHERAL). A generic clock can act as
the clock to one or several of peripherals.
14.6.2 Basic Operation
14.6.2.1 Initialization
Before a generic clock is enabled, the clock source of its generic clock generator should be enabled. The generic clock
must be configured as outlined by the following steps:
1.
The generic clock generator division factor must be set by performing a single 32-bit write to the Generic Clock
Generator Division register (GENDIV):
z
The generic clock generator that will be selected as the source of the generic clock must be written to the ID
bit group (GENDIV.ID).
z
The division factor must be written to the DIV bit group (GENDIV.DIV)
Refer to GENDIV register for details.
2.
The generic clock generator must be enabled by performing a single 32-bit write to the Generic Clock Generator
Control register (GENCTRL):
z
The generic clock generator that will be selected as the source of the generic clock must be written to the ID
bit group (GENCTRL.ID)
z
The generic clock generator must be enabled by writing a one to the GENEN bit (GENCTRL.GENEN)
Refer to GENCTRL register for details.
3.
The generic clock must be configured by performing a single 16-bit write to the Generic Clock Control register
(CLKCTRL):
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z
The generic clock that will be configured must be written to the ID bit group (CLKCTRL.ID)
z
The generic clock generator used as the source of the generic clock must be written to the GEN bit group
(CLKCTRL.GEN)
Refer to CLKCTRL register for details.
14.6.2.2 Enabling, Disabling and Resetting
The GCLK module has no enable/disable bit to enable or disable the whole module.
The GCLK is reset by writing a one to the Software Reset bit in the Control register (CTRL.SWRST). All registers in the
GCLK will be reset to their initial state except for generic clocks and associated generators that have their Write Lock bit
written to one. Refer to “Configuration Lock” on page 90 for details.
14.6.2.3 Generic Clock Generator
Each generic clock generator (GCLKGEN) can be set to run from one of eight different clock sources except
GCLKGEN[1] which can be set to run from one of seven sources. GCLKGEN[1] can act as source to the other generic
clock generators but can not act as source to itself.
Each generic clock generator GCLKGEN[x] can be connected to one specific GCLK_IO[x] pin. The GCLK_IO[x] can be
set to act as source to GCLKGEN[x] or GCLK_IO[x] can be set up to output the clock generated by GCLKGEN[x].
The selected source (GCLKGENSRC see Figure 14-3) can optionally be divided. Each generic clock generator can be
independently enabled and disabled.
Each GCLKGEN clock can then be used as a clock source for the generic clock multiplexers. Each generic clock is
allocated to one or several peripherals.
GCLKGEN[0], is used as GCLK_MAIN for the synchronous clock controller inside the Power Manager.
Refer to “PM – Power Manager” on page 107 for details on the synchronous clock generation.
Figure 14-3. Generic Clock Generator
GCLKGENSRC
Clock Sources
0
GCLKGENSRC
DIVIDER
GCLK_IO[x]
Clock
Gate
GCLKGEN[x]
1
GENCTRL.GENEN
GENCTRL.DIVSEL
GENCTRL.SRC
GENDIV.DIV
14.6.2.4 Enabling a Generic Clock Generator
A generic clock generator is enabled by writing a one to the Generic Clock Generator Enable bit in the Generic Clock
Generator Control register (GENCTRL.GENEN).
14.6.2.5 Disabling a Generic Clock Generator
A generic clock generator is disabled by writing a zero to GENCTRL.GENEN. When GENCTRL.GENEN is read as zero,
the GCLKGEN clock is disabled and clock gated.
14.6.2.6 Selecting a Clock Source for the Generic Clock Generator
Each generic clock generator can individually select a clock source by writing to the Source Select bit group in
GENCTRL (GENCTRL.SRC). Changing from one clock source, A, to another clock source, B, can be done on the fly. If
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clock source B is not ready, the generic clock generator will continue running with clock source A. As soon as clock
source B is ready, however, the generic clock generator will switch to it. During the switching, the generic clock generator
holds clock requests to clock sources A and B and then releases the clock source A request when the switch is done.
The available clock sources are device dependent (usually the crystal oscillators, RC oscillators, PLL and DFLL clocks).
GCLKGEN[1] can be used as a common source for all the generic clock generators except generic clock generator 1.
Before switching the Generic Clock Generator 0 (GCLKGEN0) from a clock source A to another clock source B, enable
the "ONDEMAND" feature of the clock source A to ensure a proper transition from clock source A to clock source B.
14.6.2.7 Changing Clock Frequency
The selected generic clock generator source, GENCLKSRC can optionally be divided by writing a division factor
in the Division Factor bit group in the Generic Clock Generator Division register (GENDIV.DIV). Depending on the value
of the Divide Selection bit in GENCTRL (GENCTRL.DIVSEL), it can be interpreted in two ways by the integer divider.
Note that the number of DIV bits for each generic clock generator is device dependent.
Refer to Table 14-9 for details.
14.6.2.8 Duty Cycle
When dividing a clock with an odd division factor, the duty-cycle will not be 50/50. Writing a one to the Improve Duty
Cycle bit in GENCTRL (GENCTRL.IDC) will result in a 50/50 duty cycle.
14.6.2.9 Generic Clock Output on I/O Pins
Each Generic Clock Generator's output can be directed to a GCLK_IO pin. If the Output Enable bit in GENCTRL
(GENCTRL.OE) is one and the generic clock generator is enabled (GENCTRL.GENEN is one), the generic clock
generator requests its clock source and the GCLKGEN clock is output to a GCLK_IO pin. If GENCTRL.OE is zero,
GCLK_IO is set according to the Output Off Value bit. If the Output Off Value bit in GENCTRL (GENCTRL.OOV) is zero,
the output clock will be low when generic clock generator is turned off. If GENCTRL.OOV is one, the output clock will be
high when generic clock generator is turned off.
In standby mode, if the clock is output (GENCTRL.OE is one), the clock on the GCLK_IO pin is frozen to the OOV value
if the Run In Standby bit in GENCTRL (GENCTRL.RUNSTDBY) is zero. If GENCTRL.RUNSTDBY is one, the GCLKGEN
clock is kept running and output to GCLK_IO.
14.6.3 Generic Clock
Figure 14-4. Generic Clock Multiplexer
GCLKGEN[0]
GCLKGEN[1]
GCLKGEN[2]
GCLKGEN[n]
Clock
Gate
GCLK_PERIPHERAL
CLKCTRL.CLKEN
CLKCTRL.GEN
14.6.3.1 Enabling a Generic Clock
Before a generic clock is enabled, one of the generic clock generators must be selected as the source for the generic
clock by writing to CLKCTRL.GEN. The clock source selection is individually set for each generic clock.
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When a generic clock generator has been selected, the generic clock is enabled by writing a one to the Clock Enable bit
in CLKCTRL (CLKCTRL.CLKEN). The CLKCTRL.CLKEN bit must be synchronized to the generic clock domain.
CLKCTRL.CLKEN will continue to read as its previous state until the synchronization is complete.
14.6.3.2 Disabling a Generic Clock
A generic clock is disabled by writing a zero to CLKCTRL.CLKEN. The SYNCBUSY bit will be cleared when this writesynchronization is complete. CLKCTRL.CLKEN will continue to read as its previous state until the synchronization is
complete. When the generic clock is disabled, the generic clock is clock gated.
14.6.3.3 Selecting a Clock Source for the Generic Clock
When changing a generic clock source by writing to CLKCTRL.GEN, the generic clock must be disabled before being reenabled with the new clock source setting. This prevents glitches during the transition:
a.
Write a zero to CLKCTRL.CLKEN
b.
Wait until CLKCTRL.CLKEN reads as zero
c.
Change the source of the generic clock by writing CLKCTRL.GEN
d.
Re-enable the generic clock by writing a one to CLKCTRL.CLKEN
14.6.3.4 Configuration Lock
The generic clock configuration is locked for further write accesses by writing the Write Lock bit (WRTLOCK) in the
CLKCTRL register. All writes to the CLKCTRL register will be ignored. It can only be unlocked by a power reset.
The generic clock generator sources of a locked generic clock are also locked. The corresponding GENCTRL and
GENDIV are locked, and can be unlocked only by a power reset.
There is one exception concerning the GCLKGEN[0]. As it is used as GCLK_MAIN, it can not be locked. It is reset by any
reset to startup with a known configuration.
The SWRST can not unlock the registers.
14.6.4 Additional Features
14.6.4.1 Indirect Access
The Generic Clock Generator Control and Division registers (GENCTRL and GENDIV) and the Generic Clock Control
register (CLKCTRL) are indirectly addressed as shown in Figure 14-5.
Figure 14-5. GCLK Indirect Access
User Interface
Generic Clock Generator [i]
GENCTRL
GENDIV
CLKCTRL
GENCTRL.ID=i
GENCTRL
GENDIV.ID=i
GENDIV
CLKCTRL.ID=j
Generic Clock[j]
CLKCTRL
Writing these registers is done by setting the corresponding ID bit group.
To read a register, the user must write the ID of the channel, i, in the corresponding register. The value of the register for
the corresponding ID is available in the user interface by a read access.
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For example, the sequence to read the GENCTRL register of generic clock generator i is:
a.
Do an 8-bit write of the i value to GENCTRL.ID
b.
Read GENCTRL
14.6.4.2 Generic Clock Enable after Reset
The Generic Clock Controller must be able to provide a generic clock to some specific peripherals after a reset. That
means that the configuration of the generic clock generators and generic clocks after reset is device-dependent.
Refer to Table 14-7 and Table 14-8 for details on GENCTRL reset.
Refer to Table 14-11 and Table 14-12 for details on GENDIV reset.
Refer to Table 14-3 and Table 14-4 for details on CLKCTRL reset.
14.6.5 Sleep Mode Operation
14.6.5.1 SleepWalking
The GCLK module supports the SleepWalking feature. During a sleep mode where the generic clocks are stopped, a
peripheral that needs its generic clock to execute a process must request it from the Generic Clock Controller.
The Generic Clock Controller will receive this request and then determine which generic clock generator is involved and
which clock source needs to be awakened. It then wakes up the clock source, enables the generic clock generator and
generic clock stages successively and delivers the generic clock to the peripheral.
14.6.5.2 Run in Standby Mode
In standby mode, the GCLK can continuously output the generic clock generator output to GCLK_IO.
Refer to “Generic Clock Output on I/O Pins” on page 89 for details.
14.6.6 Synchronization
Due to the asynchronicity between CLK_GCLK_APB and GCLKGENSRC some registers must be synchronized when
accessed. A register can require:
z
Synchronization when written
z
Synchronization when read
z
Synchronization when written and read
z
No synchronization
When executing an operation that requires synchronization, the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set immediately, and cleared when synchronization is complete.
If an operation that requires synchronization is executed while STATUS.SYNCBUSY is one, the bus will be stalled. All
operations will complete successfully, but the CPU will be stalled and interrupts will be pending as long as the bus is
stalled.
The following registers need synchronization when written:
z
Generic Clock Generator Control register (GENCTRL)
z
Generic Clock Generator Division register (GENDIV)
z
Control register (CTRL)
Write-synchronization is denoted by the Write-Synchronization property in the register description.
Refer to “Register Synchronization” on page 80 for further details.
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14.7
Register Summary
Offset
Name
Bit
Pos.
0x0
CTRL
7:0
0x1
STATUS
7:0
0x2
SWRST
SYNCBUSY
7:0
ID[5:0]
CLKCTRL
0x3
15:8
0x4
7:0
0x5
WRTLOCK
CLKEN
GEN[3:0]
ID[3:0]
15:8
SRC[4:0]
GENCTRL
0x6
23:16
0x7
31:24
0x8
7:0
0x9
RUNSTDBY
DIVSEL
OE
OOV
IDC
GENEN
ID[3:0]
15:8
DIV[7:0]
0xA
23:16
DIV[15:8]
0xB
31:24
GENDIV
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14.8
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-protected property in each individual register description. Refer to “Register Access Protection” on page 87 for
details.
Some registers require synchronization when read and/or written. Synchronization is denoted by the Write-Synchronized
or the Read-Synchronized property in each individual register description. Refer to “Synchronization” on page 91 for
details.
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14.8.1 Control
Name:
CTRL
Offset:
0x0
Reset:
0x00
Property:
Write-Protected, Write-Synchronized
Bit
7
6
5
4
3
2
1
0
SWRST
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – SWRST: Software Reset
0: There is no reset operation ongoing.
1: There is a reset operation ongoing.
Writing a zero to this bit has no effect.
Writing a one to this bit resets all registers in the GCLK to their initial state after a power reset, except for generic
clocks and associated generators that have their WRTLOCK bit in CLKCTRL read as one.
Refer to Table 14-7 for details on GENCTRL reset.
Refer to Table 14-11 for details on GENDIV reset.
Refer to Table 14-3 for details on CLKCTRL reset.
Due to synchronization, there is a delay from writing CTRL.SWRST until the reset is complete. CTRL.SWRST and
STATUS.SYNCBUSY will both be cleared when the reset is complete.
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14.8.2 Status
Name:
STATUS
Offset:
0x1
Reset:
0x00
Property:
–
Bit
7
6
5
4
3
2
1
0
SYNCBUSY
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bit 7 – SYNCBUSY: Synchronization Busy Status
This bit is cleared when the synchronization of registers between the clock domains is complete.
This bit is set when the synchronization of registers between clock domains is started.
z
Bits 6:0 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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14.8.3 Generic Clock Control
This register allows the user to configure one of the generic clocks, as specified in the CLKCTRL.ID bit group. To write to
the CLKCTRL register, do a 16-bit write with all configurations and the ID.
To read the CLKCTRL register, first do an 8-bit write to the CLKCTRL.ID bit group with the ID of the generic clock whose
configuration is to be read, and then read the CLKCTRL register.
Name:
CLKCTRL
Offset:
0x2
Reset:
0x0000
Property:
Write-Protected
Bit
15
14
WRTLOCK
CLKEN
R/W
R/W
R
R
R/W
Reset
0
0
0
0
Bit
7
6
5
4
Access
13
12
11
10
9
8
R/W
R/W
R/W
0
0
0
0
3
2
1
0
GEN[3:0]
ID[5:0]
Access
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bit 15 – WRTLOCK: Write Lock
When this bit is written, it will lock further writes to the generic clock pointed by the CLKCTRL.ID. The generic clock
generator pointed by CLKCTRL.GEN and the GENDIV.DIV will also be locked.
One exception to this is generic clock generator 0, which cannot be locked.
0: The generic clock and the associated generic clock generator and division factor are not locked.
1: The generic clock and the associated generic clock generator and division factor are locked.
z
Bit 14 – CLKEN: Clock Enable
This bit is used to enable and disable a generic clock.
0: The generic clock is disabled.
1: The generic clock is enabled.
z
Bits 13:12 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 11:8 – GEN[3:0]: Generic Clock Generator
These bits select the generic clock generator to be used as the source of a generic clock. The value of the GEN bit
group versus generic clock generator is shown in Table 14-1.
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Table 14-1. Generic Clock Generator
GEN[3:0]
Name
Description
0x0
GCLKGEN0
Generic clock generator 0
0x1
GCLKGEN1
Generic clock generator 1
0x2
GCLKGEN2
Generic clock generator 2
0x3
GCLKGEN3
Generic clock generator 3
0x4
GCLKGEN4
Generic clock generator 4
0x5
GCLKGEN5
Generic clock generator 5
0x6
GCLKGEN6
Generic clock generator 6
0x7
GCLKGEN7
Generic clock generator 7
0x8-0xF
Reserved
z
Bits 7:6 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 5:0 – ID[5:0]: Generic Clock Selection ID
These bits select the generic clock that will be configured. The value of the ID bit group versus module instance is shown
in Table 14-2.
Table 14-2. Generic Clock Selection ID
ID[5:0]
Name
Description
0x00
GCLK_DFLL48M_REF
DFLL48M Reference
0x01
GCLK_WDT
WDT
0x02
GCLK_RTC
RTC
0x03
GCLK_EIC
EIC
0x04
GCLK_EVSYS_CHANNEL_0
EVSYS_CHANNEL_0
0x05
GCLK_EVSYS_CHANNEL_1
EVSYS_CHANNEL_1
0x06
GCLK_EVSYS_CHANNEL_2
EVSYS_CHANNEL_2
0x07
GCLK_EVSYS_CHANNEL_3
EVSYS_CHANNEL_3
0x08
GCLK_EVSYS_CHANNEL_4
EVSYS_CHANNEL_4
0x09
GCLK_EVSYS_CHANNEL_5
EVSYS_CHANNEL_5
0x0A
GCLK_EVSYS_CHANNEL_6
EVSYS_CHANNEL_6
0x0B
GCLK_EVSYS_CHANNEL_7
EVSYS_CHANNEL_7
0x0C
GCLK_SERCOMx_SLOW
SERCOMx_SLOW
0x0D
GCLK_SERCOM0_CORE
SERCOM0_CORE
0x0E
GCLK_SERCOM1_CORE
SERCOM1_CORE
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Table 14-2. Generic Clock Selection ID (Continued)
0x0F
GCLK_SERCOM2_CORE
SERCOM2_CORE
0x10
GCLK_SERCOM3_CORE
SERCOM3_CORE
0x11
GCLK_SERCOM4_CORE
SERCOM4_CORE
0x12
GCLK_SERCOM5_CORE
SERCOM5_CORE
0x13
GCLK_TCC0, GCLK_TCC1
TC0,TC1
0x14
GCLK_TCC2, GCLK_TC3
TC2,TC3
0x15
GCLK_TC4, GCLK_TC5
TC4,TC5
0x16
GCLK_TC6, GCLK_TC7
TC6,TC7
0x17
GCLK_ADC
ADC
0x18
GCLK_AC_DIG
AC_DIG
0x19
GCLK_AC_ANA
AC_ANA
0x1A
GCLK_DAC
DAC
0x1B
GCLK_PTC
PTC
0x1C-0x3F
Reserved
A power reset will reset the CLKCTRL register for all IDs, including the RTC. If the WRTLOCK bit of the corresponding ID
is zero and the ID is not the RTC, a user reset will reset the CLKCTRL register for this ID.
After a power reset, the reset value of the CLKCTRL register versus module instance is as shown in Table 14-3.
Table 14-3. CLKCTRL Reset Value after a Power Reset
Module Instance
Reset Value after a Power Reset
CLKCTRL.GEN
CLKCTRL.CLKEN
CLKCTRL.WRTLOCK
0x00
0x00
0x00
WDT
0x02
0x01 if WDT Enable bit in NVM
User Row written to one
0x00 if WDT Enable bit in NVM
User Row written to zero
0x01 if WDT Always-On bit in
NVM User Row written to one
0x00 if WDT Always-On bit in
NVM User Row written to zero
Others
0x00
0x00
0x00
RTC
After a user reset, the reset value of the CLKCTRL register versus module instance is as shown in Table 14-4.
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Table 14-4. CLKCTRL Reset Value after a User Reset
Module Instance
Reset Value after a User Reset
CLKCTRL.GEN
CLKCTRL.CLKEN
CLKCTRL.WRTLOCK
0x00 if WRTLOCK=0 and
CLKEN=0
No change if WRTLOCK=1
or CLKEN=1
0x00 if WRTLOCK=0 and CLKEN=0
No change if WRTLOCK=1 or CLKEN=1
No change
WDT
0x02 if WRTLOCK=0
No change if WRTLOCK=1
If WRTLOCK=0
0x01 if WDT Enable bit in NVM User
Row written to one
0x00 if WDT Enable bit in NVM User
Row written to zero
If WRTLOCK=1 no change
No change
Others
0x00 if WRTLOCK=0
No change if WRTLOCK=1
0x00 if WRTLOCK=0
No change if WRTLOCK=1
No change
RTC
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14.8.4 Generic Clock Generator Control
This register allows the user to configure one of the generic clock generators, as specified in the GENCTRL.ID bit group.
To write to the GENCTRL register, do a 32-bit write with all configurations and the ID.
To read the GENCTRL register, first do an 8-bit write to the GENCTRL.ID bit group with the ID of the generic clock
generator those configuration is to be read, and then read the GENCTRL register.
Name:
GENCTRL
Offset:
0x4
Reset:
0x00010600(1)
Property:
Write-protected, Write-Synchronized
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
RUNSTDBY
DIVSEL
OE
OOV
IDC
GENEN
Access
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
SRC[4:0]
Access
R
R
R
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ID[3:0]
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Note:
1.
This is the reset value for Generator with ID =0. See Table 14-7 for reset value of other generators.
z
Bits 31:22 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 21 – RUNSTDBY: Run in Standby
This bit is used to keep the generic clock generator running when it is configured to be output to its dedicated
GCLK_IO pin. If GENCTRL.OE is zero, this bit has no effect and the generic clock generator will only be running if
a peripheral requires the clock.
0: The generic clock generator is stopped in standby and the GCLK_IO pin state (one or zero) will be dependent
on the setting in GENCTRL.OOV.
1: The generic clock generator is kept running and output to its dedicated GCLK_IO pin during standby mode.
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z
Bit 20 – DIVSEL: Divide Selection
This bit is used to decide how the clock source used by the generic clock generator will be divided. If the clock
source should not be divided, the DIVSEL bit must be zero and the GENDIV.DIV value for the corresponding
generic clock generator must be zero or one.
0: The generic clock generator equals the clock source divided by GENDIV.DIV.
1: The generic clock generator equals the clock source divided by 2^(GENDIV.DIV+1).
z
Bit 19 – OE: Output Enable
This bit is used to enable output of the generated clock to GCLK_IO when GCLK_IO is not selected as a source in
the GENCLK.SRC bit group.
0: The generic clock generator is not output.
1: The generic clock generator is output to the corresponding GCLK_IO, unless the corresponding GCLK_IO is
selected as a source in the GENCLK.SRC bit group.
z
Bit 18 – OOV: Output Off Value
This bit is used to control the value of GCLK_IO when GCLK_IO is not selected as a source in the GENCLK.SRC
bit group.
0: The GCLK_IO will be zero when the generic clock generator is turned off or when the OE bit is zero.
1: The GCLK_IO will be one when the generic clock generator is turned off or when the OE bit is zero.
z
Bit 17 – IDC: Improve Duty Cycle
This bit is used to improve the duty cycle of the generic clock generator when odd division factors are used.
0: The generic clock generator duty cycle is not 50/50 for odd division factors.
1: The generic clock generator duty cycle is 50/50.
z
Bit 16 – GENEN: Generic Clock Generator Enable
This bit is used to enable and disable the generic clock generator.
0: The generic clock generator is disabled.
1: The generic clock generator is enabled.
z
Bits 15:13 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 12:8 – SRC[4:0]: Source Select
These bits define the clock source to be used as the source for the generic clock generator, as shown in Table 145.
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Table 14-5. Source Select
SRC[4:0]
Name
Description
0x00
XOSC
XOSC oscillator output
0x01
GCLKIN
Generator input pad
0x02
GCLKGEN1
Generic clock generator 1 output
0x03
OSCULP32K
OSCULP32K oscillator output
0x04
OSC32K
OSC32K oscillator output
0x05
XOSC32K
XOSC32K oscillator output
0x06
OSC8M
OSC8M oscillator output
0x07
DFLL48M
DFLL48M output
0x08-0x1F
Reserved
Reserved for future use
z
Bits 7:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 3:0 – ID[3:0]: Generic Clock Generator Selection
These bits select the generic clock generator that will be configured or read. The value of the ID bit group versus
which generic clock generator is configured is shown in Table 14-6.
Table 14-6. Generic Clock Generator Selection
ID[3:0]
Name
Description
0x0
GCLKGEN0
Generic clock generator 0
0x1
GCLKGEN1
Generic clock generator 1
0x2
GCLKGEN2
Generic clock generator 2
0x3
GCLKGEN3
Generic clock generator 3
0x4
GCLKGEN4
Generic clock generator 4
0x5
GCLKGEN5
Generic clock generator 5
0x6
GCLKGEN6
Generic clock generator 6
0x7
GCLKGEN7
Generic clock generator 7
0x8-0xF
Reserved
A power reset will reset the GENCTRL register for all IDs, including the generic clock generator used by the RTC. If a
generic clock generator ID other than generic clock generator 0 is not a source of a “locked” generic clock or a source of
the RTC generic clock, a user reset will reset the GENCTRL for this ID.
After a power reset, the reset value of the GENCTRL register is as shown in Table 14-7.
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Table 14-7. GENCTRL Reset Value after a Power Reset
Generic Clock Generator ID
Reset Value after a Power Reset
Generator Clock Source
0x00
0x00010600
OSC8M
0x01
0x00000001
XOSC
0x02
0x00010302
OSCULP32K
0x03
0x00000003
XOSC
0x04
0x00000004
XOSC
0x05
0x00000005
XOSC
0x06
0x00000006
XOSC
0x07
0x00000007
XOSC
After a user reset, the reset value of the GENCTRL register is as shown in Table 14-8.
Table 14-8. GENCTRL Reset Value after a User Reset
GCLK Generator ID
Reset Value after a User Reset
0x00
0x00010600
0x01
0x00000001 if the generator is not used by the RTC and not a source of a 'locked' generic clock
No change if the generator is used by the RTC or used by a GCLK with a WRTLOCK as one
0x02
0x00010302 if the generator is not used by the RTC and not a source of a 'locked' generic clock
No change if the generator is used by the RTC or used by a GCLK with a WRTLOCK as one
0x03
0x00000003 if the generator is not used by the RTC and not a source of a 'locked' generic clock
No change if the generator is used by the RTC or used by a GCLK with a WRTLOCK as one
0x04
0x00000004 if the generator is not used by the RTC and not a source of a 'locked' generic clock
No change if the generator is used by the RTC or used by a Generic Clock with a WRTLOCK as one
0x05
0x00000005 if the generator is not used by the RTC and not a source of a 'locked' generic clock
No change if the generator is used by the RTC or used by a Generic Clock with a WRTLOCK as one
0x06
0x00000006 if the generator is not used by the RTC and not a source of a 'locked' generic clock
No change if the generator is used by the RTC or used by a Generic Clock with a WRTLOCK as one
0x07
0x00000007 if the generator is not used by the RTC and not a source of a 'locked' generic clock
No change if the generator is used by the RTC or used by a Generic Clock with a WRTLOCK as one
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14.8.5 Generic Clock Generator Division
This register allows the user to configure one of the generic clock generators, as specified in the GENDIV.ID bit group.
To write to the GENDIV register, do a 32-bit write with all configurations and the ID.
To read the GENDIV register, first do an 8-bit write to the GENDIV.ID bit group with the ID of the generic clock generator
whose configuration is to be read, and then read the GENDIV register.
Name:
GENDIV
Offset:
0x8
Reset:
0x00000000
Property:
Write-protected, Write-Synchronized
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
DIV[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
DIV[7:0]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ID[3:0]
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 31:24 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 23:8 – DIV[15:0]: Division Factor
These bits apply a division on each selected generic clock generator. The number of DIV bits each generator has
can be seen in Table 14-9. Writes to bits above the specified number will be ignored.
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Table 14-9. Division Factor
Generator
Division Factor Bits
Generic clock generator 0
8 division factor bits - DIV[7:0]
Generic clock generator 1
16 division factor bits - DIV[15:0]
Generic clock generators 2
5 division factor bits - DIV[4:0]
Generic clock generators 3 - 7
8 division factor bits - DIV[7:0]
z
Bits 7:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 3:0 – ID[3:0]: Generic Clock Generator Selection
These bits select the generic clock generator on which the division factor will be applied, as shown in Table 14-10.
Table 14-10. Generic Clock Generator Selection
ID[3:0]
Description
0x0
Generic clock generator 0
0x1
Generic clock generator 1
0x2
Generic clock generator 2
0x3
Generic clock generator 3
0x4
Generic clock generator 4
0x5
Generic clock generator 5
0x6
Generic clock generator 6
0x7
Generic clock generator 7
0x8-0xF
Reserved
A power reset will reset the GENDIV register for all IDs, including the generic clock generator used by the RTC. If a
generic clock generator ID other than generic clock generator 0 is not a source of a “locked” generic clock or a source of
the RTC generic clock, a user reset will reset the GENDIV for this ID.
After a power reset, the reset value of the GENDIV register is as shown in Table 14-11.
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Table 14-11. GENDIV Reset value after a Power Reset
GCLK Generator ID
Reset Value after a Power Reset
0x00
0x00000000
0x01
0x00000001
0x02
0x00000002
0x03
0x00000003
0x04
0x00000004
0x05
0x00000005
0x06
0x00000006
0x07
0x00000007
After a user reset, the reset value of the GENDIV register is as shown in Table 14-12.
Table 14-12. GENDIV Reset Value after a User Reset
GCLK Generator ID
Reset Value after a User Reset
0x00
0x00000000
0x01
0x00000001 if the generator is not used by the RTC
No change if the generator is used by the RTC or used by a Generic Clock with a WRTLOCK as one
0x02
0x00000002 if the generator is not used by the RTC
No change if the generator is used by the RTC or used by a Generic Clock with a WRTLOCK as one
0x03
0x00000003 if the generator is not used by the RTC
No change if the generator is used by the RTC or used by a Generic Clock with a WRTLOCK as one
0x04
0x00000004 if the generator is not used by the RTC
No change if the generator is used by the RTC or used by a Generic Clock with a WRTLOCK as one
0x05
0x00000005 if the generator is not used by the RTC
No change if the generator is used by the RTC or used by a Generic Clock with a WRTLOCK as one
0x06
0x00000006 if the generator is not used by the RTC
No change if the generator is used by the RTC or used by a Generic Clock with a WRTLOCK as one
0x07
0x00000007 if the generator is not used by the RTC
No change if the generator is used by the RTC or used by a Generic Clock with a WRTLOCK as one
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15.
PM – Power Manager
15.1
Overview
The Power Manager (PM) controls the reset, clock generation and sleep modes of the microcontroller.
Utilizing a main clock chosen from a large number of clock sources from the GCLK, the clock controller provides
synchronous system clocks to the CPU and the modules connected to the AHB and the APBx bus. The synchronous
system clocks are divided into a number of clock domains; one for the CPU and AHB and one for each APBx. Any
synchronous system clock can be changed at run-time during normal operation. The clock domains can run at different
speeds, enabling the user to save power by running peripherals at a relatively low clock frequency, while maintaining
high CPU performance. In addition, the clock can be masked for individual modules, enabling the user to minimize power
consumption. If for some reason the main clock stops oscillating, the clock failure detector allows switching the main
clock to the safe OSC8M clock.
Before entering the STANDBY sleep mode the user must make sure that a significant amount of clocks and peripherals
are disabled, so that the voltage regulator is not overloaded. This is because during STANDBY sleep mode the internal
voltage regulator will be in low power mode.
Various sleep modes and clock gating are provided in order to fit power consumption requirements. This enables the
microcontroller to stop unused modules to save power. In ACTIVE mode, the CPU is executing application code. When
the device enters a sleep mode, program execution is stopped and some modules and clock domains are automatically
switched off by the PM according to the sleep mode. The application code decides which sleep mode to enter and when.
Interrupts from enabled peripherals and all enabled reset sources can restore the microcontroller from a sleep mode to
ACTIVE mode.
The PM also contains a reset controller, which collects all possible reset sources. It issues a microcontroller reset and
sets the device to its initial state, and allows the reset source to be identified by software.
15.2
Features
z Reset control
z
Reset the microcontroller and set it to an initial state according to the reset source
Multiple reset sources
z Power reset sources: POR, BOD12, BOD33
z User reset sources: External reset (RESET), Watchdog Timer reset, software reset
z Reset status register for reading the reset source from the application code
z
z Clock control
z
Controls CPU, AHB and APB system clocks
z Multiple clock sources and division factor from GCLK
z Clock prescaler with 1x to 128x division
z Safe run-time clock switching from GCLK
z Module-level clock gating through maskable peripheral clocks
z Clock failure detector
z Power management control
z
z
Sleep modes: IDLE, STANDBY
SleepWalking support on GCLK clocks
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15.3
Block Diagram
Figure 15-1. PM Block Diagram
POWER MANAGER
CLK_APB
OSC8M
GCLK
SYNCHRONOUS
CLOCK CONTROLLER
CLK_AHB
PERIPHERALS
CLK_CPU
SLEEP MODE
CONTROLLER
CPU
BOD12
USER RESET
BOD33
POWER RESET
POR
WDT
RESET
CONTROLLER
CPU
RESET
RESET SOURCES
15.4
Signal Description
Signal Name
Type
Description
RESET
Digital input
External reset
Refer to “I/O Multiplexing and Considerations” on page 16 for details on the pin mapping for this peripheral. One signal
can be mapped on several pins.
15.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
15.5.1 I/O Lines
Not applicable.
15.5.2 Power Management
Not applicable.
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15.5.3 Clocks
The PM bus clock (CLK_PM_APB) can be enabled and disabled in the power manager, and the default state of
CLK_PM_APB can be found in Table 15-1. If this clock is disabled in the Power Manager, it can only be re-enabled by a
reset.
A generic clock (GCLK_MAIN) is required to generate the main clock. The clock source for GCLK_MAIN is configured by
default in the Generic Clock Controller, and can be re-configured by the user if needed. Refer to “GCLK – Generic Clock
Controller” on page 85 for details.
15.5.3.1 Main Clock
The main clock (CLK_MAIN) is the common source for the synchronous clocks. This is fed into the common 8-bit
prescaler that is used to generate synchronous clocks to the CPU, AHB and APBx modules.
15.5.3.2 CPU Clock
The CPU clock (CLK_CPU) is routed to the CPU. Halting the CPU clock inhibits the CPU from executing instructions.
15.5.3.3 AHB Clock
The AHB clock (CLK_AHB) is the root clock source used by peripherals requiring an AHB clock. The AHB clock is always
synchronous to the CPU clock and has the same frequency, but may run even when the CPU clock is turned off. A clock
gate is inserted from the common AHB clock to any AHB clock of a peripheral.
15.5.3.4 APBx Clocks
The APBx clock (CLK_APBX) is the root clock source used by modules requiring a clock on the APBx bus. The APBx
clock is always synchronous to the CPU clock, but can be divided by a prescaler, and will run even when the CPU clock
is turned off. A clock gater is inserted from the common APB clock to any APBx clock of a module on APBx bus.
15.5.4 Interrupts
The interrupt request line is connected to the Interrupt Controller. Using the PM interrupt requires the Interrupt Controller
to be configured first. Refer to “Nested Vector Interrupt Controller” on page 30 for details.
15.5.5 Events
Not applicable.
15.5.6 Debug Operation
When the CPU is halted in debug mode, the PM continues normal operation. In sleep mode, the clocks generated from
the PM are kept running to allow the debugger accessing any modules. As a consequence, power measurements are not
possible in debug mode.
15.5.7 Register Access Protection
All registers with write access are optionally write-protected by the Peripheral Access Controller (PAC), except the
following registers:
z
Interrupt Flag register (INTFLAG). Refer to INTFLAG for details
z
Reset Cause register (RCAUSE). Refer to RCAUSE for details
Write-protection is denoted by the Write-Protection property in the register description.
Write-protection does not apply for accesses through an external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
15.5.8 Analog Connections
Not applicable.
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15.6
Functional Description
15.6.1 Principle of Operation
15.6.1.1 Synchronous Clocks
The GCLK_MAIN clock from GCLK module provides the source for the main clock, which is the common root for the
synchronous clocks for the CPU and APBx modules. The main clock is divided by an 8-bit prescaler, and each of the
derived clocks can run from any tapping off this prescaler or the undivided main clock, as long as fCPU ≥ fAPBx. The
synchronous clock source can be changed on the fly to respond to varying load in the application. The clocks for each
module in each synchronous clock domain can be individually masked to avoid power consumption in inactive modules.
Depending on the sleep mode, some clock domains can be turned off (see Table 15-4 on page 115).
15.6.1.2 Reset Controller
The Reset Controller collects the various reset sources and generates reset for the device. The device contains a poweron-reset (POR) detector, which keeps the system reset until power is stable. This eliminates the need for external reset
circuitry to guarantee stable operation when powering up the device.
15.6.1.3 Sleep Mode Controller
In ACTIVE mode, all clock domains are active, allowing software execution and peripheral operation. The PM Sleep
Mode Controller allows the user to choose between different sleep modes depending on application requirements, to
save power (see Table 15-4 on page 115).
15.6.2 Basic Operation
15.6.2.1 Initialization
After a power-on reset, the PM is enabled and the Reset Cause (RCAUSE - refer to RCAUSE for details) register
indicates the POR source. The default clock source of the GCLK_MAIN clock is started and calibrated before the CPU
starts running. The GCLK_MAIN clock is selected as the main clock without any division on the prescaler. The device is
in the ACTIVE mode.
By default, only the necessary clocks are enabled (see Table 15-1).
15.6.2.2 Enabling, Disabling and Resetting
The PM module is always enabled and can not be reset.
15.6.2.3 Selecting the Main Clock Source
Refer to “GCLK – Generic Clock Controller” on page 85 for details on how to configure the main clock source.
15.6.2.4 Selecting the Synchronous Clock Division Ratio
The main clock feeds an 8-bit prescaler, which can be used to generate the synchronous clocks. By default, the
synchronous clocks run on the undivided main clock. The user can select a prescaler division for the CPU clock by
writing the CPU Prescaler Selection bits in the CPU Select register (CPUSEL.CPUDIV), resulting in a CPU clock
frequency determined by this equation:
f main
f CPU = ---------------------CPUDIV
2
Similarly, the clock for the APBx can be divided by writing their respective registers (APBxSEL.APBxDIV). To ensure
correct operation, frequencies must be selected so that fCPU ≥ fAPBx. Also, frequencies must never exceed the specified
maximum frequency for each clock domain.
Note that the AHB clock is always equal to the CPU clock.
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CPUSEL and APBxSEL can be written without halting or disabling peripheral modules. Writing CPUSEL and APBxSEL
allows a new clock setting to be written to all synchronous clocks at the same time. It is possible to keep one or more
clocks unchanged. This way, it is possible to, for example, scale the CPU speed according to the required performance,
while keeping the APBx frequency constant.
Figure 15-2. Synchronous Clock Selection and Prescaler
Sleep Controller
Sleep mode
APBCMASK
Clock
gate
APBCDIV
APBBDIV
GCLK
CLK_PERIPHERAL_APBC_n
CLK_PERIPHERAL_APBC_1
CLK_PERIPHERAL_APBC_0
APBBMASK
Clock
gate
Clock
gate
Clock
gate
Clock
gate
CLK_APBB
CLK_PERIPHERAL_APBB_n
CLK_PERIPHERAL_APBB_1
CLK_PERIPHERAL_APBB_0
APBAMASK
Clock
gate
GCLK_MAIN
Clock
gate
Clock
gate
Clock
gate
CLK_APBC
Clock
gate
Clock
gate
Clock
gate
CLK_PERIPHERAL_APBA_n
CLK_PERIPHERAL_APBA_1
CLK_PERIPHERAL_APBA_0
Clock
gate
Clock
gate
Clock
gate
CLK_PERIPHERAL_AHB_n
CLK_PERIPHERAL_AHB_1
CLK_PERIPHERAL_AHB_0
CLK_APBA
CLK_MAIN
APBADIV
OSC8M
BKUPCLK
Clock
Failure
Detector
Prescaler
AHBMASK
Clock
gate
CLK_AHB
Clock
gate
CLK_CPU
CPUDIV
15.6.2.5 Clock Ready Flag
There is a slight delay from when CPUSEL and APBxSEL are written until the new clock setting becomes effective.
During this interval, the Clock Ready flag in the Interrupt Flag Status and Clear register (INTFLAG.CKRDY) will read as
zero. If CKRDY in the INTENSET register is written to one, the Power Manager interrupt can be triggered when the new
clock setting is effective. CPUSEL must not be re-written while CKRDY is zero, or the system may become unstable or
hang.
15.6.2.6 Peripheral Clock Masking
It is possible to disable or enable the clock for a peripheral in the AHB or APBx clock domain by writing the corresponding
bit in the Clock Mask register (APBxMASK - refer to APBAMASK for details) to zero or one. Refer to Table 15-1 for the
default state of each of the peripheral clocks.
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Table 15-1. Peripheral Clock Default State
Peripheral Clock
Default State
CLK_PAC0_APB
Enabled
CLK_PM_APB
Enabled
CLK_SYSCTRL_APB
Enabled
CLK_GCLK_APB
Enabled
CLK_WDT_APB
Enabled
CLK_RTC_APB
Enabled
CLK_EIC_APB
Enabled
CLK_PAC1_APB
Enabled
CLK_DSU_APB
Enabled
CLK_NVMCTRL_APB
Enabled
CLK_PORT_APB
Enabled
CLK_PAC2_APB
Disabled
CLK_SERCOMx_APB
Disabled
CLK_TCx_APB
Disabled
CLK_ADC_APB
Enabled
CLK_AC_APB
Disabled
CLK_DAC_APB
Disabled
CLK_PTC_APB
Disabled
When the APB clock for a module is not provided its registers cannot be read or written. The module can be re-enabled
later by writing the corresponding mask bit to one.
A module may be connected to several clock domains (for instance, AHB and APB), in which case it will have several
mask bits.
Note that clocks should only be switched off if it is certain that the module will not be used. Switching off the clock for the
NVM Controller (NVMCTRL) will cause a problem if the CPU needs to read from the flash memory. Switching off the
clock to the Power Manager (PM), which contains the mask registers, or the corresponding APBx bridge, will make it
impossible to write the mask registers again. In this case, they can only be re-enabled by a system reset.
15.6.2.7 Clock Failure Detector
This mechanism allows the main clock to be switched automatically to the safe OSC8M clock when the main clock
source is considered off. This may happen for instance when an external crystal oscillator is selected as the clock source
for the main clock and the crystal fails. The mechanism is to designed to detect, during a OSCULP32K clock period, at
least one rising edge of the main clock. If no rising edge is seen, the clock is considered failed.
The clock failure detector is enabled by writing a one to the Clock Failure Detector Enable bit in CTRL (CFDEN_CTRL).
Refer to CTRL for detailed information.
As soon as the Clock Failure Detector Enable bit (CTRL.CFDEN) is one, the clock failure detector (CFD) will monitor the
undivided main clock. When a clock failure is detected, the main clock automatically switches to the OSC8M clock and
the Clock Failure Detector flag in the interrupt Flag Status and Clear register (INTFLAG.CFD) is set and the
corresponding interrupt request will be generated if enabled. The BKUPCLK bit in the CTRL register is set by hardware
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to indicate that the main clock comes from OSC8M. The GCLK_MAIN clock source can be selected again by writing a
zero to the CTRL.BKUPCLK bit. Writing the bit does not fix the failure, however.
Note 1: The detector does not monitor while the main clock is temporarily unavailable (startup time after a wake-up, etc.)
or in sleep mode. The Clock Failure Detector must be disabled before entering standby mode.
Note 2: The clock failure detector must not be enabled if the source of the main clock is not significantly faster than the
OSCULP32K clock. For instance, if GCLK_MAIN is the internal 32kHz RC, then the clock failure detector must be
disabled.
Note 3: The OSC8M internal oscillator should be enabled to allow the main clock switching to the OSC8M clock.
15.6.2.8 Reset Controller
The latest reset cause is available in RCAUSE, and can be read during the application boot sequence in order to
determine proper action.
There are two groups of reset sources:
z
Power Reset: Resets caused by an electrical issue.
z
User Reset: Resets caused by the application.
The table below lists the parts of the device that are reset, depending on the reset type.
Table 15-2. Effects of the Different Reset Events
Power Reset
User Reset
POR, BOD12, BOD33
External Reset
WDT Reset,
SysResetReq
RTC
All the 32kHz sources
WDT with ALWAYSON feature
Generic Clock with WRTLOCK
feature
Y
N
N
Debug logic
Y
Y
N
Others
Y
Y
Y
The external reset is generated when pulling the RESET pin low. This pin has an internal pull-up, and does not need to
be driven externally during normal operation.
The POR, BOD12 and BOD33 reset sources are generated by their corresponding module in the System Controller
Interface (SYSCTRL).
The WDT reset is generated by the Watchdog Timer.
The System Reset Request (SysResetReq) is a software reset generated by the CPU when asserting the
SYSRESETREQ bit located in the Reset Control register of the CPU (See the ARM® Cortex® Technical Reference
Manual on http://www.arm.com).
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Figure 15-3. Reset Controller
RESET CONTROLLER
BOD12
BOD33
POR
RTC
32kHz clock sources
WDT with ALWAYSON
Generic Clock with
WRTLOCK
Debug Logic
RESET
WDT
Others
CPU
RCAUSE
RESET SOURCES
15.6.2.9 Sleep Mode Controller
Sleep mode is activated by the Wait For Interrupt instruction (WFI). The Idle bits in the Sleep Mode register
(SLEEP.IDLE) and the SLEEPDEEP bit of the System Control register of the CPU should be used as argument to select
the level of the sleep mode.
There are two main types of sleep mode:
z
IDLE mode: The CPU is stopped. Optionally, some synchronous clock domains are stopped, depending on the
IDLE argument. Regulator operates in normal mode.
z
STANDBY mode: All clock sources are stopped, except those where the RUNSTDBY bit is set. Regulator operates
in low-power mode. Before entering standby mode the user must make sure that a significant amount of clocks
and peripherals are disabled, so that the voltage regulator is not overloaded.
Table 15-3. Sleep Mode Entry and Exit Table
Mode
Level
0
IDLE
1
2
STANDBY
Notes:
1.
2.
Mode Entry
SCR.SLEEPDEEP = 0
SLEEP.IDLE=Level
WFI
SCR.SLEEPDEEP = 1
WFI
Wake-Up Sources
Synchronous(2) (APB, AHB), asynchronous(1)
Synchronous (APB), asynchronous
Asynchronous
Asynchronous
Asynchronous: interrupt generated on generic clock or external clock or external event.
Synchronous: interrupt generated on the APB clock.
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Table 15-4. Sleep Mode Overview
Sleep
Mode
CPU
Clock
AHB
Clock
APB
Clock
Oscillators
ONDEMAND = 0
ONDEMAND = 1
RUNSTDBY=0
RUNSTDBY=1
RUNSTDBY=0
RUNSTDBY=1
Main
Clock
Regulator
Mode
RAM
Mode
Idle 0
Stop
Run
Run
Run
Run
Run if
requested
Run if
requested
Run
Normal
Normal
Idle 1
Stop
Stop
Run
Run
Run
Run if
requested
Run if
requested
Run
Normal
Normal
Idle 2
Stop
Stop
Stop
Run
Run
Run if
requested
Run if
requested
Run
Normal
Normal
Standby
Stop
Stop
Stop
Stop
Run
Stop
Run if
requested
Stop
Low
power
Low
power
IDLE Mode
The IDLE modes allow power optimization with the fastest wake-up time.
The CPU is stopped. To further reduce power consumption, the user can disable the clocking of modules and clock
sources by configuring the SLEEP.IDLE bit group. The module will be halted regardless of the bit settings of the mask
registers in the Power Manager (PM.AHBMASK, PM.APBxMASK).
Regulator operates in normal mode.
z
Entering IDLE mode: The IDLE mode is entered by executing the WFI instruction. Additionally, if the
SLEEPONEXIT bit in the ARM Cortex System Control register (SCR) is set, the IDLE mode will also be entered
when the CPU exits the lowest priority ISR. This mechanism can be useful for applications that only require the
processor to run when an interrupt occurs. Before entering the IDLE mode, the user must configure the IDLE mode
configuration bit group and must write a zero to the SCR.SLEEPDEEP bit.
z
Exiting IDLE mode: The processor wakes the system up when it detects the occurrence of any interrupt that is not
masked in the NVIC Controller with sufficient priority to cause exception entry. The system goes back to the
ACTIVE mode. The CPU and affected modules are restarted.
STANDBY Mode
The STANDBY mode allows achieving very low power consumption.
In this mode, all clocks are stopped except those which are kept running if requested by a running module or have the
ONDEMAND bit set to zero. For example, the RTC can operate in STANDBY mode. In this case, its Generic Clock clock
source will also be enabled.
The regulator and the RAM operate in low-power mode.
A SLEEPONEXIT feature is also available.
z
Entering STANDBY mode: This mode is entered by executing the WFI instruction with the SCR.SLEEPDEEP bit of
the CPU is written to 1.
z
Exiting STANDBY mode: Any peripheral able to generate an asynchronous interrupt can wake up the system. For
example, a module running on a Generic clock can trigger an interrupt. When the enabled asynchronous wake-up
event occurs and the system is woken up, the device will either execute the interrupt service routine or continue
the normal program execution according to the Priority Mask Register (PRIMASK) configuration of the CPU.
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15.6.3 SleepWalking
SleepWalking is the capability for a device to temporarily wakeup clocks for peripheral to perform a task without wakingup the CPU in STANDBY sleep mode. At the end of the sleepwalking task, the device can either be waken-up by an
interrupt (from a peripheral involved in SleepWalking) or enter again into STANDBY sleep mode.
In Atmel | SMART SAM D20 devices, SleepWalking is supported only on GCLK clocks by using the on-demand clock
principle of the clock sources. Refer to “On-demand, Clock Requests” on page 83 for more details.
15.6.4 Interrupts
The peripheral has the following interrupt sources:
z
Clock Ready flag
z
Clock failure detector
Each interrupt source has an interrupt flag associated with it. The interrupt flag in the Interrupt Flag Status and Clear
(INTFLAG) register is set when the interrupt condition occurs. Each interrupt can be individually enabled by writing a one
to the corresponding bit in the Interrupt Enable Set (INTENSET) register, and disabled by writing a one to the
corresponding bit in the Interrupt Enable Clear (INTENCLR) register. An interrupt request is generated when the interrupt
flag is set and the corresponding interrupt is enabled. The interrupt request remains active until the interrupt flag is
cleared, the interrupt is disabled or the peripheral is reset. An interrupt flag is cleared by writing a one to the
corresponding bit in the INTFLAG register. Each peripheral can have one interrupt request line per interrupt source or
one common interrupt request line for all the interrupt sources. Refer to “Nested Vector Interrupt Controller” on page 30
for details. If the peripheral has one common interrupt request line for all the interrupt sources, the user must read the
INTFLAG register to determine which interrupt condition is present.
15.6.5 Events
Not applicable.
15.6.6 Sleep Mode Operation
In all IDLE sleep modes, the power manager is still running on the selected main clock.
In STANDDBY sleep mode, the power manager is frozen and is able to go back to ACTIVE mode upon any
asynchronous interrupt.
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15.7
Register Summary
Offset
Name
Bit Pos.
0x00
CTRL
7:0
0x01
SLEEP
7:0
0x02
Reserved
0x03
Reserved
…
…
0x06
Reserved
0x07
Reserved
0x08
CPUSEL
7:0
CPUDIV[2:0]
0x09
APBASEL
7:0
APBADIV[2:0]
0x0A
APBBSEL
7:0
APBBDIV[2:0]
0x0B
APBCSEL
7:0
APBCDIV[2:0]
0x0C
Reserved
0x0D
Reserved
…
BKUPCLK
CFDEN
IDLE[1:0]
…
…
…
…
…
…
…
…
…
0x12
Reserved
0x13
Reserved
0x14
7:0
0x15
NVMCTRL
DSU
HPB2
HPB1
HPB0
WDT
GCLK
SYSCTRL
PM
PAC0
PORT
NVMCTRL
DSU
PAC1
15:8
AHBMASK
0x16
23:16
0x17
31:24
0x18
7:0
0x19
EIC
RTC
15:8
APBAMASK
0x1A
23:16
0x1B
31:24
0x1C
7:0
0x1D
15:8
APBBMASK
0x1E
23:16
0x1F
31:24
0x20
7:0
SERCOM5
SERCOM4
SERCOM3
SERCOM2
SERCOM1
SERCOM0
EVSYS
PAC2
15:8
TC7
TC6
TC5
TC4
TC3
TC2
TC1
TC0
PTC
DAC
AC
ADC
…
…
…
…
0x21
APBCMASK
0x22
23:16
0x23
31:24
0x24
Reserved
0x25
Reserved
…
…
0x32
Reserved
…
…
…
…
…
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Offset
Name
Bit Pos.
0x33
Reserved
0x34
INTENCLR
7:0
CFD
CKRDY
0x35
INTENSET
7:0
CFD
CKRDY
0x36
INTFLAG
7:0
CFD
CKRDY
0x37
Reserved
0x38
RCAUSE
BOD12
POR
7:0
SYST
WDT
EXT
BOD33
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15.8
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register, and the 8-bit halves of a 16-bit register can be accessed directly.
Exception for APBASEL, APBBSEL and APBCSEL: These registers must only be accessed with 8-bit access.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-Protected property in each individual register description. Refer to “Register Access Protection” on page 109
for details.
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15.8.1 Control
Name:
CTRL
Offset:
0x00
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
BKUPCLK
2
1
0
CFDEN
Access
R
R
R
R/W
R
R/W
R
R
Reset
0
0
0
0
0
0
0
0
z
Bits 7:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 4 – BKUPCLK: Backup Clock Select
This bit is set by hardware when a clock failure is detected.
0: The GCLK_MAIN clock is selected for the main clock.
1: The OSC8M backup clock is selected for the main clock.
z
Bit 3 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 2 – CFDEN: Clock Failure Detector Enable
0: The clock failure detector is disabled.
1: The clock failure detector is enabled.
z
Bits 1:0 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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15.8.2 Sleep Mode
Name:
SLEEP
Offset:
0x01
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
IDLE[1:0]
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 1:0 – IDLE[1:0]: Idle Mode Configuration
These bits select the Idle mode configuration after a WFI instruction.
Table 15-5. Idle Mode Configuration
IDLE[1:0]
Description
0x0
The CPU clock domain is stopped
0x1
The CPU and AHB clock domains are stopped
0x2
The CPU, AHB and APB clock domains are stopped
0x3
Reserved
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15.8.3 CPU Clock Select
Name:
CPUSEL
Offset:
0x08
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
CPUDIV[2:0]
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 2:0 – CPUDIV[2:0]: CPU Prescaler Selection
These bits define the division ratio of the main clock prescaler (2n).
Table 15-6. CPU Clock Frequency Ratio
CPUDIV[1:0]
Description
0x0
Divide by 1
0x1
Divide by 2
0x2
Divide by 4
0x3
Divide by 8
0x4
Divide by 16
0x5
Divide by 32
0x6
Divide by 64
0x7
Divide by 128
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15.8.4 APBA Clock Select
Name:
APBASEL
Offset:
0x09
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
APBADIV[2:0]
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 2:0 – APBADIV[2:0]: APBA Prescaler Selection
These bits define the division ratio of the APBA clock prescaler (2n).
Table 15-7. APBA Prescaler Selection
APBADIV[1:0]
Description
0x0
Divide by 1
0x1
Divide by 2
0x2
Divide by 4
0x3
Divide by 8
0x4
Divide by 16
0x5
Divide by 32
0x6
Divide by 64
0x7
Divide by 128
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15.8.5 APBB Clock Select
Name:
APBBSEL
Offset:
0x0A
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
APBBDIV[2:0]
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 2:0 – APBBDIV[2:0]: APBB Prescaler Selection
These bits define the division ratio of the APBB clock prescaler (2n).
Table 15-8. APBB Prescaler Selection
APBBDIV[1:0]
Description
0x0
Divide by 1
0x1
Divide by 2
0x2
Divide by 4
0x3
Divide by 8
0x4
Divide by 16
0x5
Divide by 32
0x6
Divide by 64
0x7
Divide by 128
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15.8.6 APBC Clock Select
Name:
APBCSEL
Offset:
0x0B
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
APBCDIV[2:0]
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 2:0 – APBCDIV[2:0]: APBC Prescaler Selection
These bits define the division ratio of the APBC clock prescaler (2n).
Table 15-9. APBC Prescaler Selection
APBCDIV[1:0]
Description
0x0
Divide by 1
0x1
Divide by 2
0x2
Divide by 4
0x3
Divide by 8
0x4
Divide by 16
0x5
Divide by 32
0x6
Divide by 64
0x7
Divide by 128
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15.8.7 AHB Mask
Name:
AHBMASK
Offset:
0x14
Reset:
0x0000001F
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
NVMCTRL
DSU
HPB2
HPB1
HPB0
Access
R
R
R
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
1
1
1
1
1
z
Bits 31:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 4:0 – NVMCTRL, DSU, HPB2, HPB1, HPB0: AHB Clock Enable
For any bit:
0: The AHB clock for the corresponding module is stopped.
1: The AHB clock for the corresponding module is enabled.
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15.8.8 APBA Mask
Name:
APBAMASK
Offset:
0x18
Reset:
0x0000007F
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
EIC
RTC
WDT
GCLK
SYSCTRL
PM
PAC0
Access
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
1
1
1
1
1
1
1
z
Bits 31:7 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 6:0 – EIC, RTC, WDT, GCLK, SYSCTRL, PM, PAC0: APB Clock Enable
For any bit:
0: The APBA clock for the corresponding module is stopped.
1: The APBA clock for the corresponding module is enabled.
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15.8.9 APBB Mask
Name:
APBBMASK
Offset:
0x1C
Reset:
0x0000001F
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
PORT
NVMCTRL
DSU
PAC1
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
1
1
1
1
1
z
Bits 31:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 3:0 – PORT, NVMCTRL, DSU, PAC1: APB Clock Enable
For any bit:
0: The APBB clock for the corresponding module is stopped.
1: The APBB clock for the corresponding module is enabled.
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15.8.10 APBC Mask
Name:
APBCMASK
Offset:
0x20
Reset:
0x00010000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
23
22
21
20
19
18
17
16
PTC
DAC
AC
ADC
Bit
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
1
Bit
15
14
13
12
11
10
9
8
TC7
TC6
TC5
TC4
TC3
TC2
TC1
TC0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
SERCOM5
SERCOM4
SERCOM3
SERCOM2
SERCOM1
SERCOM0
EVSYS
PAC2
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Access
Access
Reset
z
Bits 31:20 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 19:0 – PTC, DAC, AC, ADC, TC7, TC6, TC5, TC4, TC3, TC2, TC1, TC0, SERCOM5, SERCOM4,
SERCOM3, SERCOM2, SERCOM1, SERCOM0, EVSYS, PAC2: APB Clock Enable
For any bit:
0: The APBC clock for the corresponding module is stopped.
1: The APBC clock for the corresponding module is enabled.
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15.8.11 Interrupt Enable Clear
This register allows the user to disable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Set (INTENSET) register.
Name:
INTENCLR
Offset:
0x34
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
CFD
CKRDY
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – CFD: Clock Failure Detector Interrupt Enable
0: The Clock Failure Detector interrupt is disabled.
1: The Clock Failure Detector interrupt is enabled and an interrupt request will be generated when the Clock Failure Detector Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Clock Failure Detector Interrupt Enable bit and the corresponding interrupt
request.
z
Bit 0 – CKRDY: Clock Ready Interrupt Enable
0: The Clock Ready interrupt is disabled.
1: The Clock Ready interrupt is enabled and will generate an interrupt request when the Clock Ready Interrupt flag
is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Clock Ready Interrupt Enable bit and the corresponding interrupt request.
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15.8.12 Interrupt Enable Set
This register allows the user to enable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Clear (INTENCLR) register.
Name:
INTENSET
Offset:
0x35
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
CFD
CKRDY
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – CFD: Clock Failure Detector Interrupt Enable
0: The Clock Failure Detector interrupt is disabled.
1: The Clock Failure Detector interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Clock Failure Detector Interrupt Enable bit and enable the Clock Failure Detector interrupt.
z
Bit 0 – CKRDY: Clock Ready Interrupt Enable
0: The Clock Ready interrupt is disabled.
1: The Clock Ready interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Clock Ready Interrupt Enable bit and enable the Clock Ready interrupt.
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15.8.13 Interrupt Flag Status and Clear
Name:
INTFLAG
Offset:
0x36
Reset:
0x00
Property:
–
Bit
7
6
5
4
3
2
1
0
CFD
CKRDY
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – CFD: Clock Failure Detector
This flag is cleared by writing a one to the flag.
This flag is set on the next cycle after a clock failure detector occurs and will generate an interrupt request if
INTENCLR/SET.CFD is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Clock Failure Detector Interrupt flag.
z
Bit 0 – CKRDY: Clock Ready
This flag is cleared by writing a one to the flag.
This flag is set when the synchronous CPU and APBx clocks have frequencies as indicated in the CPUSEL and
APBxSEL registers, and will generate an interrupt if INTENCLR/SET.CKRDY is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Clock Ready Interrupt flag.
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15.8.14 Reset Cause
Name:
RCAUSE
Offset:
0x38
Reset:
Latest Reset Source
Property:
–
Bit
7
6
5
4
SYST
WDT
EXT
3
2
1
0
BOD33
BOD12
POR
Access
R
R
R
R
R
R
R
R
Reset
0
X
X
X
0
X
X
X
z
Bit 7 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 6 – SYST: System Reset Request
This bit is set if a system reset request has been performed. Refer to the Cortex processor documentation for more
details.
z
Bit 5 – WDT: Watchdog Reset
This flag is set if a Watchdog Timer reset occurs.
z
Bit 4 – EXT: External Reset
This flag is set if an external reset occurs.
z
Bit 3 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 2 – BOD33: Brown Out 33 Detector Reset
This flag is set if a BOD33 reset occurs.
z
Bit 1 – BOD12: Brown Out 12 Detector Reset
This flag is set if a BOD12 reset occurs.
z
Bit 0 – POR: Power-On Reset
This flag is set if a POR occurs.
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16.
16.1
SYSCTRL – System Controller
Overview
The System Controller (SYSCTRL) provides a user interface to the clock sources, brown out detectors, on-chip voltage
regulator and voltage reference of the device.
Through the interface registers, it is possible to enable, disable, calibrate and monitor the SYSCTRL sub-peripherals.
All sub-peripheral statuses are collected in the Power and Clocks Status register (PCLKSR - refer to PCLKSR). They can
additionally trigger interrupts upon status changes via the INTENSET (INTENSET), INTENCLR (INTENCLR) and
INTFLAG (INTFLAG) registers.
Additionally, BOD33 interrupts can be used to wake up the device from standby mode upon a programmed brown-out
detection.
16.2
Features
z 0.4-32MHz Crystal Oscillator (XOSC)
z
Tunable gain control
Programmable start-up time
z Crystal or external input clock on XIN I/O
z
z 32.768kHz Crystal Oscillator (XOSC32K)
z
Automatic or manual gain control
Programmable start-up time
z Crystal or external input clock on XIN32 I/O
z
z 32.768kHz High Accuracy Internal Oscillator (OSC32K)
z
z
Frequency fine tuning
Programmable start-up time
z 32.768kHz Ultra Low Power Internal Oscillator (OSCULP32K)
z
Ultra low power, always-on oscillator
Frequency fine tuning
z Calibration value loaded from Flash Factory Calibration at reset
z
z 8MHz Internal Oscillator (OSC8M)
z
Fast startup
Output frequency fine tuning
z 4/2/1MHz divided output frequencies available
z Calibration value loaded from Flash Factory Calibration at reset
z
z Digital Frequency Locked Loop (DFLL48M)
z
Internal oscillator with no external components
48MHz output frequency
z Operates standalone as a high-frequency programmable oscillator in open loop mode
z Operates as an accurate frequency multiplier against a known frequency in closed loop mode
z
z 3.3V Brown-Out Detector (BOD33)
z
Programmable threshold
Threshold value loaded from Flash User Calibration at startup
z Triggers resets or interrupts
z Operating modes:
z Continuous mode
z Sampled mode for low power applications (programmable refresh frequency)
z Hysteresis
z
z Internal Voltage Regulator system (VREG)
z
Operating modes:
z Normal mode
z Low-power mode
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z
With an internal non-configurable Brown-out detector (BOD12)
z Voltage Reference System (VREF)
z
Bandgap voltage generator with programmable calibration value
Temperature sensor
z Bandgap calibration value loaded from Flash Factory Calibration at startup
z
16.3
Block Diagram
Figure 16-1. SYSCTRL Block Diagram
SYSCTRL
XOSC
XOSC32K
OSCILLATORS
CONTROL
OSC32K
OSCULP32K
OSC8M
DFLL48M
POWER
MONITOR
CONTROL
BOD33
VOLTAGE
REFERENCE
CONTROL
VOLTAGE
REFERENCE
SYSTEM
STATUS
(PCLKSR register)
INTERRUPTS
GENERATOR
Interrupts
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16.4
Signal Description
Signal Name
Types
XIN
Analog Input
XOUT
Analog Output
XIN32
Analog Input
XOUT32
Analog Output
Description
Multipurpose Crystal Oscillator or external
clock generator input
External Multipurpose Crystal Oscillator
output
32kHz Crystal Oscillator or external clock
generator input
32kHz Crystal Oscillator output
The I/O lines are automatically selected when XOSC or XOSC32K are enabled.
16.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
16.5.1 I/O Lines
I/O lines are configured by SYSCTRL when either XOSC or XOSC32K are enabled, and need no user configuration.
16.5.2 Power Management
The SYSCTRL can continue to operate in any sleep mode where the selected source clock is running. The SYSCTRL
interrupts can be used to wake up the device from sleep modes. The events can trigger other operations in the system
without exiting sleep modes. Refer to “PM – Power Manager” on page 107 for details on the different sleep modes.
16.5.3 Clocks
The SYSCTRL gathers controls for all device oscillators and provides clock sources to the Generic Clock Controller
(GCLK). The available clock sources are: XOSC, XOSC32K, OSC32K, OSCULP32K, OSC8M and DFLL48M.
The SYSCTRL bus clock (CLK_SYSCTRL_APB) can be enabled and disabled in the Power Manager, and the default
state of CLK_SYSCTRL_APB can be found in the Peripheral Clock Masking section in the “PM – Power Manager” on
page 107.
The clock used by BOD33in sampled mode is asynchronous to the user interface clock (CLK_SYSCTRL_APB).
Likewise, the DFLL48M control logic uses the DFLL oscillator output, which is also asynchronous to the user interface
clock (CLK_SYSCTRL_APB). Due to this asynchronicity, writes to certain registers will require synchronization between
the clock domains. Refer to “Synchronization” on page 145 for further details.
16.5.4 Interrupts
The interrupt request line is connected to the Interrupt Controller. Using the SYSCTRL interrupts requires the interrupt
controller to be configured first. Refer to “Nested Vector Interrupt Controller” on page 30 for details.
16.5.5 Debug Operation
When the CPU is halted in debug mode, the SYSCTRL continues normal operation. If the SYSCTRL is configured in a
way that requires it to be periodically serviced by the CPU through interrupts or similar, improper operation or data loss
may result during debugging.
If a debugger connection is detected by the system, BOD33 reset will be blocked.
16.5.6 Register Access Protection
All registers with write-access are optionally write-protected by the peripheral access controller (PAC), except the
following registers:
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z
Interrupt Flag Status and Clear register (INTFLAG - refer to INTFLAG)
Write-protection is denoted by the Write-Protection property in the register description.
When the CPU is halted in debug mode, all write-protection is automatically disabled.
Write-protection does not apply for accesses through an external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
16.5.7 Analog Connections
When used, the 32.768kHz crystal must be connected between the XIN32 and XOUT32 pins, and the 0.4-32MHz crystal
must be connected between the XIN and XOUT pins, along with any required load capacitors. For details on
recommended oscillator characteristics and capacitor load, refer to the “Electrical Characteristics” on page 571 for
details.
16.6
Functional Description
16.6.1 Principle of Operation
XOSC, XOSC32K, OSC32K, OSCULP32K, OSC8M, DFLL48M, BOD33, and VREF are configured via SYSCTRL control
registers. Through this interface, the sub-peripherals are enabled, disabled or have their calibration values updated.
The Power and Clocks Status register gathers different status signals coming from the sub-peripherals controlled by the
SYSCTRL. The status signals can be used to generate system interrupts, and in some cases wake up the system from
standby mode, provided the corresponding interrupt is enabled.
The oscillator must be enabled to run. The oscillator is enabled by writing a one to the ENABLE bit in the respective
oscillator control register, and disabled by writing a zero to the oscillator control register. In idle mode, the default
operation of the oscillator is to run only when requested by a peripheral. In standby mode, the default operation of the
oscillator is to stop. This behavior can be changed by the user, see below for details.
The behavior of the oscillators in the different sleep modes is shown in Table 16-1 on page 137
Table 16-1. Behavior of the Oscillators
Oscillator
Idle 0,
1,
2
Standby
XOSC
Run on request
Stop
XOSC32K
Run on request
Stop
OSC32K
Run on request
Stop
OSCULP32K
Run
Run
OSC8M
Run on request
Stop
DFLL48M
Run on request
Stop
To force an oscillator to always run in idle mode, and not only when requested by a peripheral, the oscillator
ONDEMAND bit must be written to zero. The default value of this bit is one, and thus the default operation in idle mode is
to run only when requested by a peripheral.
To force the oscillator to run in standby mode, the RUNSTDBY bit must be written to one. The oscillator will then run in
standby mode when requested by a peripheral (ONDEMAND is one). To force an oscillator to always run in standby
mode, and not only when requested by a peripheral, the ONDEMAND bit must be written to zero and RUNSTDBY must
be written to one.
Table 16-2 on page 138 shows the behavior in the different sleep modes, depending on the settings of ONDEMAND and
RUNSTDBY.
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Table 16-2. Behavior in the different sleep modes
Sleep mode
ONDEMAND
RUNSTDBY
Behavior
Idle
0,
1,
2
0
X
Run
Idle
0,
1,
2
1
X
Run when requested by a peripheral
Standby
0
0
Stop
Standby
0
1
Run
Standby
1
0
Stop
Standby
1
1
Run when requested by a peripheral
Note that this does not apply to the OSCULP32K oscillator, which is always running and cannot be disabled.
16.6.2 External Multipurpose Crystal Oscillator (XOSC) Operation
The XOSC can operate in two different modes:
z
External clock, with an external clock signal connected to the XIN pin
z
Crystal oscillator, with an external 0.4-32MHz crystal
The XOSC can be used as a clock source for generic clock generators, as described in the “GCLK – Generic Clock
Controller” on page 85.
At reset, the XOSC is disabled, and the XIN/XOUT pins can be used as General Purpose I/O (GPIO) pins or by other
peripherals in the system. When XOSC is enabled, the operating mode determines the GPIO usage. When in crystal
oscillator mode, the XIN and XOUT pins are controlled by the SYSCTRL, and GPIO functions are overridden on both
pins. When in external clock mode, only the XIN pin will be overridden and controlled by the SYSCTRL, while the XOUT
pin can still be used as a GPIO pin.
The XOSC is enabled by writing a one to the Enable bit in the External Multipurpose Crystal Oscillator Control register
(XOSC.ENABLE). To enable the XOSC as a crystal oscillator, a one must be written to the XTAL Enable bit
(XOSC.XTALEN). If XOSC.XTALEN is zero, external clock input will be enabled.
When in crystal oscillator mode (XOSC.XTALEN is one), the External Multipurpose Crystal Oscillator Gain (XOSC.GAIN)
must be set to match the external crystal oscillator frequency. If the External Multipurpose Crystal Oscillator Automatic
Amplitude Gain Control (XOSC.AMPGC) is one, the oscillator amplitude will be automatically adjusted, and in most
cases result in a lower power consumption.
The XOSC will behave differently in different sleep modes based on the settings of XOSC.RUNSTDBY,
XOSC.ONDEMAND and XOSC.ENABLE:
XOSC.RUNSTDBY
XOSC.ONDEMAND
XOSC.ENABLE
Sleep Behavior
-
-
0
Disabled
0
0
1
Always run in IDLE sleep modes.
Disabled in STANDBY sleep mode.
0
1
1
Only run in IDLE sleep modes if
requested by a peripheral. Disabled in
STANDBY sleep mode.
1
0
1
Always run in IDLE and STANDBY sleep
modes.
1
1
1
Only run in IDLE or STANDBY sleep
modes if requested by a peripheral.
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After a hard reset, or when waking up from a sleep mode where the XOSC was disabled, the XOSC will need a certain
amount of time to stabilize on the correct frequency. This start-up time can be configured by changing the Oscillator
Start-Up Time bit group (XOSC.STARTUP) in the External Multipurpose Crystal Oscillator Control register. During the
start-up time, the oscillator output is masked to ensure that no unstable clock propagates to the digital logic. The External
Multipurpose Crystal Oscillator Ready bit in the Power and Clock Status register (PCLKSR.XOSCRDY) is set when the
user-selected startup time is over. An interrupt is generated on a zero-to-one transition on PCLKSR.XOSCRDY if the
External Multipurpose Crystal Oscillator Ready bit in the Interrupt Enable Set register (INTENSET.XOSCRDY) is set.
Note:
Do not enter standby mode when an oscillator is in startup:
Wait for the OSCxRDY bit in SYSCTRL.PCLKSR register to be set before going into standby mode.
16.6.3 32kHz External Crystal Oscillator (XOSC32K) Operation
The XOSC32K can operate in two different modes:
z
External clock, with an external clock signal connected to XIN32
z
Crystal oscillator, with an external 32.768kHz crystal connected between XIN32 and XOUT32
The XOSC32K can be used as a source for generic clock generators, as described in the “GCLK – Generic Clock
Controller” on page 85.
At power-on reset (POR) the XOSC32K is disabled, and the XIN32/XOUT32 pins can be used as General Purpose I/O
(GPIO) pins or by other peripherals in the system. When XOSC32K is enabled, the operating mode determines the GPIO
usage. When in crystal oscillator mode, XIN32 and XOUT32 are controlled by the SYSCTRL, and GPIO functions are
overridden on both pins. When in external clock mode, only the XIN32 pin will be overridden and controlled by the
SYSCTRL, while the XOUT32 pin can still be used as a GPIO pin.
The external clock or crystal oscillator is enabled by writing a one to the Enable bit (XOSC32K.ENABLE) in the 32kHz
External Crystal Oscillator Control register. To enable the XOSC32K as a crystal oscillator, a one must be written to the
XTAL Enable bit (XOSC32K.XTALEN). If XOSC32K.XTALEN is zero, external clock input will be enabled.
The oscillator is disabled by writing a zero to the Enable bit (XOSC32K.ENABLE) in the 32kHz External Crystal Oscillator
Control register while keeping the other bits unchanged. Writing to the XOSC32K.ENABLE bit while writing to other bits
may result in unpredictable behavior. The oscillator remains enabled in all sleep modes if it has been enabled
beforehand. The start-up time of the 32kHz External Crystal Oscillator is selected by writing to the Oscillator Start-Up
Time bit group (XOSC32K.STARTUP) in the in the 32kHz External Crystal Oscillator Control register. The SYSCTRL
masks the oscillator output during the start-up time to ensure that no unstable clock propagates to the digital logic. The
32kHz External Crystal Oscillator Ready bit (PCLKSR.XOSC32KRDY) in the Power and Clock Status register is set
when the user-selected startup time is over. An interrupt is generated on a zero-to-one transition of
PCLKSR.XOSC32KRDY if the 32kHz External Crystal Oscillator Ready bit (INTENSET.XOSC32KRDY) in the Interrupt
Enable Set Register is set.
As a crystal oscillator usually requires a very long start-up time (up to one second), the 32kHz External Crystal Oscillator
will keep running across resets, except for power-on reset (POR).
XOSC32K can provide two clock outputs when connected to a crystal. The XOSC32K has a 32.768kHz output enabled
by writing a one to the 32kHz External Crystal Oscillator 32kHz Output Enable bit (XOSC32K.EN32K) in the 32kHz
External Crystal Oscillator Control register. XOSC32K.EN32K is only usable when XIN32 is connected to a crystal, and
not when an external digital clock is applied on XIN32.
Note:
Do not enter standby mode when an oscillator is in startup:
Wait for the OSCxRDY bit in SYSCTRL.PCLKSR register to be set before going into standby mode.
16.6.4 32kHz Internal Oscillator (OSC32K) Operation
The OSC32K provides a tunable, low-speed and low-power clock source.
The OSC32K can be used as a source for the generic clock generators, as described in the “GCLK – Generic Clock
Controller” on page 85.
The OSC32K is disabled by default. The OSC32K is enabled by writing a one to the 32kHz Internal Oscillator Enable bit
(OSC32K.ENABLE) in the 32kHz Internal Oscillator Control register. It is disabled by writing a zero to OSC32K.ENABLE.
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The OSC32K has a 32.768kHz output enabled by writing a one to the 32kHz Internal Oscillator 32kHz Output Enable bit
(OSC32K.EN32K).
The frequency of the OSC32K oscillator is controlled by the value in the 32kHz Internal Oscillator Calibration bits
(OSC32K.CALIB) in the 32kHz Internal Oscillator Control register. The OSC32K.CALIB value must be written by the
user. Flash Factory Calibration values are stored in the NVM Software Calibration Area (refer to “NVM Software
Calibration Area Mapping” on page 28). When writing to the Calibration bits, the user must wait for the
PCLKSR.OSC32KRDY bit to go high before the value is committed to the oscillator.
16.6.5 32kHz Ultra Low Power Internal Oscillator (OSCULP32K) Operation
The OSCULP32K provides a tunable, low-speed and ultra-low-power clock source. The OSCULP32K is factorycalibrated under typical voltage and temperature conditions. The OSCULP32K should be preferred to the OSC32K
whenever the power requirements are prevalent over frequency stability and accuracy.
The OSCULP32K can be used as a source for the generic clock generators, as described in the “GCLK – Generic Clock
Controller” on page 85.
The OSCULP32K is enabled by default after a power-on reset (POR) and will always run except during POR. The
OSCULP32K has a 32.768kHz output is always running.
The frequency of the OSCULP32K oscillator is controlled by the value in the 32kHz Ultra Low Power Internal Oscillator
Calibration bits (OSCULP32K.CALIB) in the 32kHz Ultra Low Power Internal Oscillator Control register.
OSCULP32K.CALIB is automatically loaded from Flash Factory Calibration during startup, and is used to compensate for
process variation, as described in the “Electrical Characteristics” on page 571. The calibration value can be overridden
by the user by writing to OSCULP32K.CALIB.
16.6.6 8MHz Internal Oscillator (OSC8M) Operation
OSC8M is an internal oscillator operating in open-loop mode and generating an 8MHz frequency. The OSC8M is factorycalibrated under typical voltage and temperature conditions.
OSC8M is the default clock source that is used after a power-on reset (POR). The OSC8M can be used as a source for
the generic clock generators, as described in the “GCLK – Generic Clock Controller” on page 85, as well as function as
the backup clock if a main clock failure is detected.
In order to enable OSC8M, the Oscillator Enable bit in the OSC8M Control register (OSC8M.ENABLE) must be written to
one. OSC8M will not be enabled until OSC8M.ENABLE is set. In order to disable OSC8M, OSC8M.ENABLE must be
written to zero. OSC8M will not be disabled until OSC8M is cleared.
The frequency of the OSC8M oscillator is controlled by the value in the calibration bits (OSC8M.CALIB) in the OSC8M
Control register. CALIB is automatically loaded from Flash Factory Calibration during startup, and is used to compensate
for process variation, as described in the “Electrical Characteristics” on page 571.
The user can control the oscillation frequency by writing to the Frequency Range (FRANGE) and Calibration (CALIB) bit
groups in the 8MHz RC Oscillator Control register (OSC8M). It is not recommended to update the FRANGE and CALIB
bits when the OSC8M is enabled. As this is in open-loop mode, the frequency will be voltage, temperature and process
dependent. Refer to the “Electrical Characteristics” on page 571 for details.
OSC8M is automatically switched off in certain sleep modes to reduce power consumption, as described in the “PM –
Power Manager” on page 107.
16.6.7 Digital Frequency Locked Loop (DFLL48M) Operation
The DFLL48M can operate in both open-loop mode and closed-loop mode. In closed-loop mode, a low-frequency clock
with high accuracy can be used as the reference clock to get high accuracy on the output clock (CLK_DFLL48M).
The DFLL48M can be used as a source for the generic clock generators, as described in the “GCLK – Generic Clock
Controller” on page 85.
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16.6.7.1 Basic Operation
Open-Loop Operation
After any reset, the open-loop mode is selected. When operating in open-loop mode, the output frequency of the
DFLL48M will be determined by the values written to the DFLL Coarse Value bit group and the DFLL Fine Value bit
group (DFLLVAL.COARSE and DFLLVAL.FINE) in the DFLL Value register.
It is possible to change the values of DFLLVAL.COARSE and DFLLVAL.FINE and thereby the output frequency of the
DFLL48M output clock, CLK_DFLL48M, while the DFLL48M is enabled and in use. CLK_DFLL48M is ready to be used
when PCLKSR.DFLLRDY is set after enabling the DFLL48M.
Closed-Loop Operation
In closed-loop operation, the output frequency is continuously regulated against a reference clock. Once the
multiplication factor is set, the oscillator fine tuning is automatically adjusted. The DFLL48M must be correctly configured
before closed-loop operation can be enabled. After enabling the DFLL48M, it must be configured in the following way:
1.
Enable and select a reference clock (CLK_DFLL48M_REF). CLK_DFLL48M_REF is Generic Clock Channel 0
(DFLL48M_Reference). Refer to “GCLK – Generic Clock Controller” on page 85 for details.
2.
Select the maximum step size allowed in finding the Coarse and Fine values by writing the appropriate values to
the DFLL Coarse Maximum Step and DFLL Fine Maximum Step bit groups (DFLLMUL.CSTEP and DFLLMUL.FSTEP) in the DFLL Multiplier register. A small step size will ensure low overshoot on the output frequency,
but will typically result in longer lock times. A high value might give a large overshoot, but will typically provide
faster locking. DFLLMUL.CSTEP and DFLLMUL.FSTEP should not be higher than 50% of the maximum value of
DFLLVAL.COARSE and DFLLVAL.FINE, respectively.
3.
Select the multiplication factor in the DFLL Multiply Factor bit group (DFLLMUL.MUL) in the DFLL Multiplier register. Care must be taken when choosing DFLLMUL.MUL so that the output frequency does not exceed the
maximum frequency of the DFLL. If the target frequency is below the minimum frequency of the DFLL48M, the output frequency will be equal to the DFLL minimum frequency.
4.
Start the closed loop mode by writing a one to the DFLL Mode Selection bit (DFLLCTRL.MODE) in the DFLL Control register.
The frequency of CLK_DFLL48M (Fclkdfll48m) is given by:
F clkdfll48m = DFLLMUL ⋅ MUL × F clkdfll48mref
where Fclkdfll48mref is the frequency of the reference clock (CLK_DFLL48M_REF). DFLLVAL.COARSE and
DFLLVAL.FINE are read-only in closed-loop mode, and are controlled by the frequency tuner to meet user specified
frequency. In closed-loop mode, the value in DFLLVAL.COARSE is used by the frequency tuner as a starting point for
Coarse. Writing DFLLVAL.COARSE to a value close to the final value before entering closed-loop mode will reduce the
time needed to get a lock on Coarse.
Frequency Locking
The locking of the frequency in closed-loop mode is divided into two stages. In the first, coarse stage, the control logic
quickly finds the correct value for DFLLVAL.COARSE and sets the output frequency to a value close to the correct
frequency. On coarse lock, the DFLL Locked on Coarse Value bit (PCLKSR.DFLLLOCKC) in the Power and Clocks
Status register will be set.
In the second, fine stage, the control logic tunes the value in DFLLVAL.FINE so that the output frequency is very close to
the desired frequency. On fine lock, the DFLL Locked on Fine Value bit (PCLKSR.DFLLLOCKF) in the Power and Clocks
Status register will be set.
Interrupts are generated by both PCLKSR.DFLLLOCKC and PCLKSR.DFLLLOCKF if INTENSET.DFLLOCKC or
INTENSET.DFLLOCKF are written to one.
CLK_DFLL48M is ready to be used when the DFLL Ready bit (PCLKSR.DFLLRDY) in the Power and Clocks Status
register is set, but the accuracy of the output frequency depends on which locks are set. For lock times, refer to the
“Electrical Characteristics” on page 571.
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Frequency Error Measurement
The ratio between CLK_DFLL48M_REF and CLK48M_DFLL is measured automatically when the DFLL48M is in closedloop mode. The difference between this ratio and the value in DFLLMUL.MUL is stored in the DFLL Multiplication Ratio
Difference bit group(DFLLVAL.DIFF) in the DFLL Value register. The relative error on CLK_DFLL48M compared to the
target frequency is calculated as follows:
DIFF
ERROR = -------------MUL
Drift Compensation
If the Stable DFLL Frequency bit (DFLLCTRL.STABLE) in the DFLL Control register is zero, the frequency tuner will
automatically compensate for drift in the CLK_DFLL48M without losing either of the locks. This means that
DFLLVAL.FINE can change after every measurement of CLK_DFLL48M. If the DFLLVAL.FINE value overflows or
underflows due to large drift in temperature and/or voltage, the DFLL Out Of Bounds bit (PCLKSR.DFLLOOB) in the
Power and Clocks Status register will be set. After an Out of Bounds error condition, the user must rewrite
DFLLMUL.MUL to ensure correct CLK_DFLL48M frequency. An interrupt is generated on a zero-to-one transition on
PCLKSR.DFLLOOB if the DFLL Out Of Bounds bit (INTENSET.DFLLOOB) in the Interrupt Enable Set register is set.
This interrupt will also be triggered if the tuner is not able to lock on the correct Coarse value.
Reference Clock Stop Detection
If CLK_DFLL48M_REF stops or is running at a very low frequency (slower than CLK_DFLL48M/(2 * MULMAX)), the DFLL
Reference Clock Stopped bit (PCLKSR.DFLLRCS) in the Power and Clocks Status register will be set. Detecting a
stopped reference clock can take a long time, on the order of 217 CLK_DFLL48M cycles. When the reference clock is
stopped, the DFLL48M will operate as if in open-loop mode. Closed-loop mode operation will automatically resume if the
CLK_DFLL48M_REF is restarted. An interrupt is generated on a zero-to-one transition on PCLKSR.DFLLRCS if the
DFLL Reference Clock Stopped bit (INTENSET.DFLLRCS) in the Interrupt Enable Set register is set.
16.6.7.2 Additional Features
Dealing with Delay in the DFLL in Closed-Loop Mode
The time from selecting a new CLK_DFLL48M frequency until this frequency is output by the DFLL48M can be up to
several microseconds. If the value in DFLLMUL.MUL is small, this can lead to instability in the DFLL48M locking
mechanism, which can prevent the DFLL48M from achieving locks. To avoid this, a chill cycle, during which the
CLK_DFLL48M frequency is not measured, can be enabled. The chill cycle is enabled by default, but can be disabled by
writing a one to the DFLL Chill Cycle Disable bit (DFLLCTRL.CCDIS) in the DFLL Control register. Enabling chill cycles
might double the lock time.
Another solution to this problem consists of using less strict lock requirements. This is called Quick Lock (QL), which is
also enabled by default, but it can be disabled by writing a one to the Quick Lock Disable bit (DFLLCTRL.QLDIS) in the
DFLL Control register. The Quick Lock might lead to a larger spread in the output frequency than chill cycles, but the
average output frequency is the same.
Wake from Sleep Modes
DFLL48M can optionally reset its lock bits when it is disabled. This is configured by the Lose Lock After Wake bit
(DFLLCTRL.LLAW) in the DFLL Control register. If DFLLCTRL.LLAW is zero, the DFLL48M will be re-enabled and start
running with the same configuration as before being disabled, even if the reference clock is not available. The locks will
not be lost. When the reference clock has restarted, the Fine tracking will quickly compensate for any frequency drift
during sleep if DFLLCTRL.STABLE is zero. If DFLLCTRL.LLAW is one when the DFLL is turned off, the DFLL48M will
lose all its locks, and needs to regain these through the full lock sequence.
Accuracy
There are three main factors that determine the accuracy of Fclkdfll48m. These can be tuned to obtain maximum accuracy
when fine lock is achieved.
z
Fine resolution: The frequency step between two Fine values. This is relatively smaller for high output frequencies.
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z
Resolution of the measurement: If the resolution of the measured Fclkdfll48m is low, i.e., the ratio between the
CLK_DFLL48M frequency and the CLK_DFLL48M_REF frequency is small, then the DFLL48M might lock at a
frequency that is lower than the targeted frequency. It is recommended to use a reference clock frequency of
32kHz or lower to avoid this issue for low target frequencies.
z
The accuracy of the reference clock.
16.6.8 3.3V Brown-Out Detector Operation
The 3.3V BOD monitors the 3.3V VDDANA supply (BOD33). It supports continuous or sampling modes.
The threshold value action (reset the device or generate an interrupt), the Hysteresis configuration, as well as the
enable/disable settings are loaded from Flash User Calibration at startup, and can be overridden by writing to the
corresponding BOD33 register bit groups.
16.6.8.1 3.3V Brown-Out Detector (BOD33)
The 3.3V Brown-Out Detector (BOD33) monitors the VDDANA supply and compares the voltage with the brown-out
threshold level set in the BOD33 Level bit group (BOD33.LEVEL) in the BOD33 register. The BOD33 can generate either
an interrupt or a reset when VDDANA crosses below the brown-out threshold level. The BOD33 detection status can be
read from the BOD33 Detection bit (PCLKSR.BOD33DET) in the Power and Clocks Status register.
At startup or at power-on reset (POR), the BOD33 register values are loaded from the Flash User Row. Refer to “NonVolatile Memory (NVM) User Row Mapping” on page 27 for more details.
16.6.8.2 Continuous Mode
When the BOD33 Mode bit (BOD33.MODE) in the BOD33 register is written to zero and the BOD33 is enabled, the
BOD33 operates in continuous mode. In this mode, the BOD33 is continuously monitoring the VDDANA supply voltage.
Continuous mode is the default mode for BOD33.
16.6.8.3 Sampling Mode
The sampling mode is a low-power mode where the BOD33 is being repeatedly enabled on a sampling clock’s ticks. The
BOD33 will monitor the supply voltage for a short period of time and then go to a low-power disabled state until the next
sampling clock tick.
Sampling mode is enabled by writing one to BOD33.MODE. The frequency of the clock ticks (Fclksampling) is controlled by
the BOD33 Prescaler Select bit group (BOD33.PSEL) in the BOD33 register.
F clkprescaler
F clksampling = -----------------------------2 ( PSEL + 1 )
The prescaler signal (Fclkprescaler) is a 1kHz clock, output from the32kHz Ultra Low Power Oscillator, OSCULP32K.
As the sampling mode clock is different from the APB clock domain, synchronization among the clocks is necessary.
Figure 16-2 shows a block diagram of the sampling mode. The BOD33Synchronization Ready bits (PCLKSR.B33SRDY)
in the Power and Clocks Status register show the synchronization ready status of the synchronizer. Writing attempts to
the BOD33 register are ignored while PCLKSR.B33SRDY is zero.
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Figure 16-2. Sampling Mode Block diagram
USER INTERFACE
REGISTERS
(APB clock domain)
PSEL
CEN
PRESCALER
(clk_prescaler
domain)
SYNCHRONIZER
MODE
CLK_SAMPLING
ENABLE
CLK_APB
CLK_PRESCALER
The BOD33 Clock Enable bit (BOD33.CEN) in the BOD33 register should always be disabled before changing the
prescaler value. To change the prescaler value for the BOD33 during sampling mode, the following steps need to be
taken:
1. Wait until the PCLKSR.B33SRDY bit is set.
2. Write the selected value to the BOD33.PSEL bit group.
16.6.8.4 Hysteresis
The hysteresis functionality can be used in both continuous and sampling mode. Writing a one to the BOD33 Hysteresis
bit (BOD33.HYST) in the BOD33 register will add hysteresis to the BOD33 threshold level.
16.6.9 Voltage Reference System Operation
The Voltage Reference System (VREF) consists of a Bandgap Reference Voltage Generator and a temperature sensor.
The Bandgap Reference Voltage Generator is factory-calibrated under typical voltage and temperature conditions.
At reset, the VREF.CAL register value is loaded from Flash Factory Calibration.
The temperature sensor can be used to get an absolute temperature in the temperature range of CMIN to CMAX
degrees Celsius. The sensor will output a linear voltage proportional to the temperature. The output voltage and
temperature range are located in the “Electrical Characteristics” on page 571. To calculate the temperature from a
measured voltage, the following formula can be used:
Δtemperature
C MIN + ( Vmes – Vout MAX ) -----------------------------------Δvoltage
16.6.9.1 User Control of the Voltage Reference System
To enable the temperature sensor, write a one the Temperature Sensor Enable bit (VREF.TSEN) in the VREF register.
The temperature sensor can be redirected to the ADC for conversion. The Bandgap Reference Voltage Generator output
can also be routed to the ADC if the Bandgap Output Enable bit (VREF.BGOUTEN) in the VREF register is set.
The Bandgap Reference Voltage Generator output level is determined by the CALIB bit group (VREF.CALIB) value in the
VREF register.The default calibration value can be overridden by the user by writing to the CALIB bit group.
16.6.10 Internal Voltage Regulator System (VREG)
The embedded Voltage Regulator (VREG) is an internal voltage regulator that supplies the core and digital logic.
The regulator has two operating modes:
z
a normal operating mode: used when the CPU and peripherals are running
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z
a low-power operating mode: used when the regulator draws small static current. By default, this mode is used in
standby sleep mode. It is possible to have the voltage regulator operate in normal mode when the chip is in
standby sleep mode: this is done by setting the VREG.RUNSTDBY bit.
The low-power operating mode has two possible configurations in standby sleep mode:
z
a low drive configuration, this is the default setting (the VREG.FORCELDO bit is cleared),
z
a high drive configuration: this setting is required for higher loads in standby sleep mode (case where several
modules are up despite the standby mode). To activate this configuration, the FORCELDO bit
(VREG.FORCELDO) in the VREG register must be set.
The internal voltage regulator system contains an internal brown-out detector(BOD12) on VDDCORE. BOD12 is
calibrated in production and its calibration configuration is stored in the NVM User Row. This configuration must not be
changed to assure the correct behavior of the BOD12. The BOD12 can generate either an interrupt or a reset when
VDDCORE crosses below the preset brown-out level. The BOD12 is always disabled in standby sleep mode.
16.6.11 Interrupts
The SYSCTRL has the following interrupt sources:
z
z
z
z
z
z
z
z
z
z
z
z
XOSCRDY - Multipurpose Crystal Oscillator Ready: A “0-to-1” transition on the PCLKSR.XOSCRDY bit is detected
XOSC32KRDY - 32kHz Crystal Oscillator Ready: A “0-to-1” transition on the PCLKSR.XOSC32KRDY bit is detected
OSC32KRDY - 32kHz Internal Oscillator Ready: A “0-to-1” transition on the PCLKSR.OSC32KRDY bit is detected
OSC8MRDY - 8MHz Internal Oscillator Ready: A “0-to-1” transition on the PCLKSR.OSC8MRDY bit is detected
DFLLRDY - DFLL48M Ready: A “0-to-1” transition on the PCLKSR.DFLLRDY bit is detected
DFLLOOB - DFLL48M Out Of Boundaries: A “0-to-1” transition on the PCLKSR.DFLLOOB bit is detected
DFLLLOCKF - DFLL48M Fine Lock: A “0-to-1” transition on the PCLKSR.DFLLLOCKF bit is detected
DFLLLOCKC - DFLL48M Coarse Lock: A “0-to-1” transition on the PCLKSR.DFLLLOCKC bit is detected
DFLLRCS - DFLL48M Reference Clock has Stopped: A “0-to-1” transition on the PCLKSR.DFLLRCS bit is detected
BOD33RDY - BOD33 Ready: A “0-to-1” transition on the PCLKSR.BOD33RDY bit is detected
BOD33DET - BOD33 Detection: A “0-to-1” transition on the PCLKSR.BOD33DET bit is detected. This is an
asynchronous interrupt and can be used to wake-up the device from any sleep mode.
B33SRDY - BOD33 Synchronization Ready: A “0-to-1” transition on the PCLKSR.B33SRDY bit is detected
Each interrupt source has an interrupt flag associated with it. The interrupt flag in the Interrupt Flag Status and Clear
(INTFLAG) register is set when the interrupt condition occurs. Each interrupt can be individually enabled by writing a one
to the corresponding bit in the Interrupt Enable Set (INTENSET) register, and disabled by writing a one to the
corresponding bit in the Interrupt Enable Clear (INTENCLR) register. An interrupt request is generated when the interrupt
flag is set and the corresponding interrupt is enabled. The interrupt request remains active until the interrupt flag is
cleared, the interrupt is disabled, or the SYSCTRL is reset. See Interrupt Flag Status and Clear (INTFLAG) register for
details on how to clear interrupt flags.
All interrupt requests from the peripheral are ORed together on system level to generate one combined interrupt request
to the NVIC. Refer to “Nested Vector Interrupt Controller” on page 30 for details. The user must read the INTFLAG
register to determine which interrupt condition is present.
Note that interrupts must be globally enabled for interrupt requests to be generated. Refer to “Nested Vector Interrupt
Controller” on page 30 for details.
16.6.12 Synchronization
Due to the multiple clock domains, values in the DFLL48M control registers need to be synchronized to other clock
domains. The status of this synchronization can be read from the Power and Clocks Status register (PCLKSR). Before
writing to any of the DFLL48M control registers, the user must check that the DFLL Ready bit (PCLKSR.DFLLRDY) in
PCLKSR is set to one. When this bit is set, the DFLL48M can be configured and CLK_DFLL48M is ready to be used. Any
write to any of the DFLL48M control registers while DFLLRDY is zero will be ignored. An interrupt is generated on a zeroto-one transition of DFLLRDY if the DFLLRDY bit (INTENSET.DFLLDY) in the Interrupt Enable Set register is set.
In order to read from any of the DFLL48M configuration registers, the user must request a read synchronization by
writing a one to DFLLSYNC.READREQ. The registers can be read only when PCLKSR.DFLLRDY is set. If
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DFLLSYNC.READREQ is not written before a read, a synchronization will be started, and the bus will be halted until the
synchronization is complete. Reading the DFLL48M registers when the DFLL48M is disabled will not halt the bus.
The prescaler counter used to trigger one-shot brown-out detections also operates asynchronously from the peripheral
bus. As a consequence, the prescaler registers require synchronization when written or read. The synchronization
results in a delay from when the initialization of the write or read operation begins until the operation is complete.
The write-synchronization is triggered by a write to the BOD33 control register. The Synchronization Ready bit
(PCLKSR.B33SRDY) in the PCLKSR register will be cleared when the write-synchronization starts and set when the
write-synchronization is complete. When the write-synchronization is ongoing (PCLKSR.B33SRDYis zero), an attempt to
do any of the following will cause the peripheral bus to stall until the synchronization is complete:
z
Writing to the BOD33control register
z
Reading the BOD33 control register that was written
The user can either poll PCLKSR.B33SRDY or use the INTENSET.B33SRDY interrupts to check when the
synchronization is complete. It is also possible to perform the next read/write operation and wait, as this next operation
will be completed after the ongoing read/write operation is synchronized.
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16.7
Register Summary
SYSCTRL Register Summary
Offset
Name
0x00
Bit
Pos.
7:0
0x01
DFLLLCKC
DFLLLCKF
DFLLOOB
DFLLRDY
15:8
OSC8MRDY
OSC32KRDY
XOSC32KRDY
XOSCRDY
B33SRDY
BOD33DET
BOD33RDY
DFLLRCS
OSC8MRDY
OSC32KRDY
XOSC32KRDY
XOSCRDY
B33SRDY
BOD33DET
BOD33RDY
DFLLRCS
OSC8MRDY
OSC32KRDY
XOSC32KRDY
XOSCRDY
B33SRDY
BOD33DET
BOD33RDY
DFLLRCS
OSC8MRDY
OSC32KRDY
XOSC32KRDY
XOSCRDY
B33SRDY
BOD33DET
BOD33RDY
DFLLRCS
XTALEN
ENABLE
INTENCLR
0x02
23:16
0x03
31:24
0x04
7:0
0x05
15:8
DFLLLCKC
DFLLLCKF
DFLLOOB
DFLLRDY
INTENSET
0x06
23:16
0x07
31:24
0x08
7:0
0x09
DFLLLCKC
DFLLLCKF
DFLLOOB
DFLLRDY
15:8
INTFLAG
0x0A
23:16
0x0B
31:24
0x0C
7:0
0x0D
15:8
DFLLLCKC
DFLLLCKF
DFLLOOB
DFLLRDY
PCLKSR
0x0E
23:16
0x0F
31:24
0x10
7:0
ONDEMAND
RUNSTDBY
XOSC
0x11
15:8
0x12
Reserved
0x13
Reserved
0x14
7:0
STARTUP[3:0]
ONDEMAND
RUNSTDBY
AMPGC
AAMPEN
EN32K
GAIN[2:0]
XTALEN
ENABLE
XOSC32K
0x15
15:8
0x16
Reserved
0x17
Reserved
0x18
7:0
0x19
15:8
STARTUP[2:0]
WRTLOCK
ONDEMAND
RUNSTDBY
EN32K
ENABLE
STARTUP[2:0]
WRTLOCK
OSC32K
0x1A
23:16
0x1B
CALIB[6:0]
31:24
0x1C
OSCULP32K
0x1D
Reserved
0x1E
Reserved
0x1F
Reserved
0x20
0x21
7:0
WRTLOCK
7:0
ONDEMAND
CALIB[4:0]
RUNSTDBY
ENABLE
15:8
PRESC[1:0]
OSC8M
0x22
23:16
0x23
31:24
0x24
7:0
CALIB[7:0]
FRANGE[1:0]
ONDEMAND
CALIB[11:8]
LLAW
STABLE
MODE
ENABLE
DFLLCTRL
0x25
15:8
0x26
Reserved
0x27
Reserved
QLDIS
CCDIS
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SYSCTRL Register Summary (Continued)
Offset
Name
0x28
Bit
Pos.
7:0
0x29
FINE[7:0]
15:8
COARSE[5:0]
FINE[9:8]
DFLLVAL
0x2A
23:16
DIFF[7:0]
0x2B
31:24
DIFF[15:8]
0x2C
7:0
MUL[7:0]
0x2D
15:8
MUL[15:8]
0x2E
23:16
FSTEP[7:0]
0x2F
31:24
DFLLMUL
0x30
DFLLSYNC
0x31
Reserved
0x32
Reserved
0x33
Reserved
7:0
0x34
7:0
0x35
15:8
CSTEP[5:0]
FSTEP[9:8]
READREQ
RUNSTDBY
ACTION[1:0]
HYST
PSEL[3:0]
ENABLE
CEN
MODE
BOD33
0x36
23:16
0x37
31:24
0x38
Reserved
...
...
0x3B
Reserved
0x3C
7:0
LEVEL[5:0]
RUNSTDBY
VREG
0x3D
15:8
0x3E
Reserved
0x3F
Reserved
0x40
FORCELDO
7:0
0x41
BGOUTEN
TSEN
15:8
VREF
0x42
23:16
0x43
31:24
0x45
Reserved
0x46
Reserved
0x47
Reserved
0x51
Reserved
0x52
Reserved
0x53
Reserved
CALIB[7:0]
CALIB[10:8]
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16.8
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-Protected property in each individual register description. Refer to “Register Access Protection” on page 136
and the “PAC – Peripheral Access Controller” on page 34 for details.
Some registers require synchronization when read and/or written. Synchronization is denoted by the Synchronized
property in each individual register description. Refer to “Synchronization” on page 145 for details.
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16.8.1 Interrupt Enable Clear
This register allows the user to disable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Set register (INTENSET).
Name:
INTENCLR
Offset:
0x00
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
B33SRDY
BOD33DET
BOD33RDY
DFLLRCS
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DFLLLCKC
DFLLLCKF
DFLLOOB
DFLLRDY
OSC8MRDY
OSC32KRDY
XOSC32KRDY
XOSCRDY
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Access
Reset
z
Bits 31:12 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 11 – B33SRDY: BOD33 Synchronization Ready Interrupt Enable
0: The BOD33 Synchronization Ready interrupt is disabled.
1: The BOD33 Synchronization Ready interrupt is enabled, and an interrupt request will be generated when the
BOD33 Synchronization Ready Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the BOD33 Synchronization Ready Interrupt Enable bit, which disables the
BOD33 Synchronization Ready interrupt.
z
Bit 10 – BOD33DET: BOD33 Detection Interrupt Enable
0: The BOD33 Detection interrupt is disabled.
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1: The BOD33 Detection interrupt is enabled, and an interrupt request will be generated when the BOD33 Detection Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the BOD33 Detection Interrupt Enable bit, which disables the BOD33 Detection
interrupt.
z
Bit 9 – BOD33RDY: BOD33 Ready Interrupt Enable
0: The BOD33 Ready interrupt is disabled.
1: The BOD33 Ready interrupt is enabled, and an interrupt request will be generated when the BOD33 Ready
Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the BOD33 Ready Interrupt Enable bit, which disables the BOD33 Ready
interrupt.
z
Bit 8 – DFLLRCS: DFLL Reference Clock Stopped Interrupt Enable
0: The DFLL Reference Clock Stopped interrupt is disabled.
1: The DFLL Reference Clock Stopped interrupt is enabled, and an interrupt request will be generated when the
DFLL Reference Clock Stopped Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the DFLL Reference Clock Stopped Interrupt Enable bit, which disables the DFLL
Reference Clock Stopped interrupt.
z
Bit 7 – DFLLLCKC: DFLL Lock Coarse Interrupt Enable
0: The DFLL Lock Coarse interrupt is disabled.
1: The DFLL Lock Coarse interrupt is enabled, and an interrupt request will be generated when the DFLL Lock
Coarse Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the DFLL Lock Coarse Interrupt Enable bit, which disables the DFLL Lock Coarse
interrupt.
z
Bit 6 – DFLLLCKF: DFLL Lock Fine Interrupt Enable
0: The DFLL Lock Fine interrupt is disabled.
1: The DFLL Lock Fine interrupt is enabled, and an interrupt request will be generated when the DFLL Lock Fine
Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the DFLL Lock Fine Interrupt Enable bit, which disables the DFLL Lock Fine
interrupt.
z
Bit 5 – DFLLOOB: DFLL Out Of Bounds Interrupt Enable
0: The DFLL Out Of Bounds interrupt is disabled.
1: The DFLL Out Of Bounds interrupt is enabled, and an interrupt request will be generated when the DFLL Out Of
Bounds Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the DFLL Out Of Bounds Interrupt Enable bit, which disables the DFLL Out Of
Bounds interrupt.
z
Bit 4 – DFLLRDY: DFLL Ready Interrupt Enable
0: The DFLL Ready interrupt is disabled.
1: The DFLL Ready interrupt is enabled, and an interrupt request will be generated when the DFLL Ready Interrupt
flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the DFLL Ready Interrupt Enable bit, which disables the DFLL Ready interrupt.
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z
Bit 3 – OSC8MRDY: OSC8M Ready Interrupt Enable
0: The OSC8M Ready interrupt is disabled.
1: The OSC8M Ready interrupt is enabled, and an interrupt request will be generated when the OSC8M Ready
Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the OSC8M Ready Interrupt Enable bit, which disables the OSC8M Ready
interrupt.
z
Bit 2 – OSC32KRDY: OSC32K Ready Interrupt Enable
0: The OSC32K Ready interrupt is disabled.
1: The OSC32K Ready interrupt is enabled, and an interrupt request will be generated when the OSC32K Ready
Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the OSC32K Ready Interrupt Enable bit, which disables the OSC32K Ready
interrupt.
z
Bit 1 – XOSC32KRDY: XOSC32K Ready Interrupt Enable
0: The XOSC32K Ready interrupt is disabled.
1: The XOSC32K Ready interrupt is enabled, and an interrupt request will be generated when the XOSC32K
Ready Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the XOSC32K Ready Interrupt Enable bit, which disables the XOSC32K Ready
interrupt.
z
Bit 0 – XOSCRDY: XOSC Ready Interrupt Enable
0: The XOSC Ready interrupt is disabled.
1: The XOSC Ready interrupt is enabled, and an interrupt request will be generated when the XOSC Ready Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the XOSC Ready Interrupt Enable bit, which disables the XOSC Ready interrupt.
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16.8.2 Interrupt Enable Set
This register allows the user to enable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Clear register (INTENCLR).
Name:
INTENSET
Offset:
0x04
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
B33SRDY
BOD33DET
BOD33RDY
DFLLRCS
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DFLLLCKC
DFLLLCKF
DFLLOOB
DFLLRDY
OSC8MRDY
OSC32KRDY
XOSC32KRDY
XOSCRDY
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Access
Reset
z
Bits 31:12 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 11 – B33SRDY: BOD33 Synchronization Ready Interrupt Enable
0: The BOD33 Synchronization Ready interrupt is disabled.
1: The BOD33 Synchronization Ready interrupt is enabled, and an interrupt request will be generated when the
BOD33 Synchronization Ready Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the BOD33 Synchronization Ready Interrupt Enable bit, which enables the BOD33
Synchronization Ready interrupt.
z
Bit 10 – BOD33DET: BOD33 Detection Interrupt Enable
0: The BOD33 Detection interrupt is disabled.
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1: The BOD33 Detection interrupt is enabled, and an interrupt request will be generated when the BOD33 Detection Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the BOD33 Detection Interrupt Enable bit, which enables the BOD33 Detection
interrupt.
z
Bit 9 – BOD33RDY: BOD33 Ready Interrupt Enable
0: The BOD33 Ready interrupt is disabled.
1: The BOD33 Ready interrupt is enabled, and an interrupt request will be generated when the BOD33 Ready
Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the BOD33 Ready Interrupt Enable bit, which enables the BOD33 Ready interrupt.
z
Bit 8 – DFLLRCS: DFLL Reference Clock Stopped Interrupt Enable
0: The DFLL Reference Clock Stopped interrupt is disabled.
1: The DFLL Reference Clock Stopped interrupt is enabled, and an interrupt request will be generated when the
DFLL Reference Clock Stopped Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the DFLL Reference Clock Stopped Interrupt Enable bit, which enables the DFLL
Reference Clock Stopped interrupt.
z
Bit 7 – DFLLLCKC: DFLL Lock Coarse Interrupt Enable
0: The DFLL Lock Coarse interrupt is disabled.
1: The DFLL Lock Coarse interrupt is enabled, and an interrupt request will be generated when the DFLL Lock
Coarse Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the DFLL Lock Coarse Interrupt Enable bit, which enables the DFLL Lock Coarse
interrupt.
z
Bit 6 – DFLLLCKF: DFLL Lock Fine Interrupt Enable
0: The DFLL Lock Fine interrupt is disabled.
1: The DFLL Lock Fine interrupt is enabled, and an interrupt request will be generated when the DFLL Lock Fine
Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the DFLL Lock Fine Interrupt Disable/Enable bit, disable the DFLL Lock Fine interrupt and set the corresponding interrupt request.
z
Bit 5 – DFLLOOB: DFLL Out Of Bounds Interrupt Enable
0: The DFLL Out Of Bounds interrupt is disabled.
1: The DFLL Out Of Bounds interrupt is enabled, and an interrupt request will be generated when the DFLL Out Of
Bounds Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the DFLL Out Of Bounds Interrupt Enable bit, which enables the DFLL Out Of
Bounds interrupt.
z
Bit 4 – DFLLRDY: DFLL Ready Interrupt Enable
0: The DFLL Ready interrupt is disabled.
1: The DFLL Ready interrupt is enabled, and an interrupt request will be generated when the DFLL Ready Interrupt
flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the DFLL Ready Interrupt Enable bit, which enables the DFLL Ready interrupt and
set the corresponding interrupt request.
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z
Bit 3 – OSC8MRDY: OSC8M Ready Interrupt Enable
0: The OSC8M Ready interrupt is disabled.
1: The OSC8M Ready interrupt is enabled, and an interrupt request will be generated when the OSC8M Ready
Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the OSC8M Ready Interrupt Enable bit, which enables the OSC8M Ready interrupt.
z
Bit 2 – OSC32KRDY: OSC32K Ready Interrupt Enable
0: The OSC32K Ready interrupt is disabled.
1: The OSC32K Ready interrupt is enabled, and an interrupt request will be generated when the OSC32K Ready
Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the OSC32K Ready Interrupt Enable bit, which enables the OSC32K Ready
interrupt.
z
Bit 1 – XOSC32KRDY: XOSC32K Ready Interrupt Enable
0: The XOSC32K Ready interrupt is disabled.
1: The XOSC32K Ready interrupt is enabled, and an interrupt request will be generated when the XOSC32K
Ready Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the XOSC32K Ready Interrupt Enable bit, which enables the XOSC32K Ready
interrupt.
z
Bit 0 – XOSCRDY: XOSC Ready Interrupt Enable
0: The XOSC Ready interrupt is disabled.
1: The XOSC Ready interrupt is enabled, and an interrupt request will be generated when the XOSC Ready Interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the XOSC Ready Interrupt Enable bit, which enables the XOSC Ready interrupt.
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16.8.3 Interrupt Flag Status and Clear
Name:
INTFLAG
Offset:
0x08
Reset:
0x00000000
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
B33SRDY
BOD33DET
BOD33RDY
DFLLRCS
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DFLLLCKC
DFLLLCKF
DFLLOOB
DFLLRDY
OSC8MRDY
OSC32KRDY
XOSC32KRDY
XOSCRDY
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Access
Reset
Note:
Depending on the fuse settings, various bits of the INTFLAG register can be set to one at startup. Therefore the user should clear those bits before using
the corresponding interrupts.
z
Bits 31:12 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 11 – B33SRDY: BOD33 Synchronization Ready
This flag is cleared by writing a one to it.
This flag is set on a zero-to-one transition of the BOD33 Synchronization Ready bit in the Status register
(PCLKSR.B33SRDY) and will generate an interrupt request if INTENSET.B33SRDY is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the BOD33 Synchronization Ready interrupt flag
z
Bit 10 – BOD33DET: BOD33 Detection
This flag is cleared by writing a one to it.
This flag is set on a zero-to-one transition of the BOD33 Detection bit in the Status register (PCLKSR.BOD33DET)
and will generate an interrupt request if INTENSET.BOD33DET is one.
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Writing a zero to this bit has no effect.
Writing a one to this bit clears the BOD33 Detection interrupt flag.
z
Bit 9 – BOD33RDY: BOD33 Ready
This flag is cleared by writing a one to it.
This flag is set on a zero-to-one transition of the BOD33 Ready bit in the Status register (PCLKSR.BOD33RDY)
and will generate an interrupt request if INTENSET.BOD33RDY is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the BOD33 Ready interrupt flag.
z
Bit 8 – DFLLRCS: DFLL Reference Clock Stopped
This flag is cleared by writing a one to it.
This flag is set on a zero-to-one transition of the DFLL Reference Clock Stopped bit in the Status register
(PCLKSR.DFLLRCS) and will generate an interrupt request if INTENSET.DFLLRCS is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the DFLL Reference Clock Stopped interrupt flag.
z
Bit 7 – DFLLLCKC: DFLL Lock Coarse
This flag is cleared by writing a one to it.
This flag is set on a zero-to-one transition of the DFLL Lock Coarse bit in the Status register (PCLKSR.DFLLLCKC) and will generate an interrupt request if INTENSET.DFLLLCKC is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the DFLL Lock Coarse interrupt flag.
z
Bit 6 – DFLLLCKF: DFLL Lock Fine
This flag is cleared by writing a one to it.
This flag is set on a zero-to-one transition of the DFLL Lock Fine bit in the Status register (PCLKSR.DFLLLCKF)
and will generate an interrupt request if INTENSET.DFLLLCKF is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the DFLL Lock Fine interrupt flag.
z
Bit 5 – DFLLOOB: DFLL Out Of Bounds
This flag is cleared by writing a one to it.
This flag is set on a zero-to-one transition of the DFLL Out Of Bounds bit in the Status register (PCLKSR.DFLLOOB) and will generate an interrupt request if INTENSET.DFLLOOB is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the DFLL Out Of Bounds interrupt flag.
z
Bit 4 – DFLLRDY: DFLL Ready
This flag is cleared by writing a one to it.
This flag is set on a zero-to-one transition of the DFLL Ready bit in the Status register (PCLKSR.DFLLRDY) and
will generate an interrupt request if INTENSET.DFLLRDY is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the DFLL Ready interrupt flag.
z
Bit 3 – OSC8MRDY: OSC8M Ready
This flag is cleared by writing a one to it.
This flag is set on a zero-to-one transition of the OSC8M Ready bit in the Status register (PCLKSR.OSC8MRDY)
and will generate an interrupt request if INTENSET.OSC8MRDY is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the OSC8M Ready interrupt flag.
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z
Bit 2 – OSC32KRDY: OSC32K Ready
This flag is cleared by writing a one to it.
This flag is set on a zero-to-one transition of the OSC32K Ready bit in the Status register (PCLKSR.OSC32KRDY)
and will generate an interrupt request if INTENSET.OSC32KRDY is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the OSC32K Ready interrupt flag.
z
Bit 1 – XOSC32KRDY: XOSC32K Ready
This flag is cleared by writing a one to it.
This flag is set on a zero-to-one transition of the XOSC32K Ready bit in the Status register
(PCLKSR.XOSC32KRDY) and will generate an interrupt request if INTENSET.XOSC32KRDY is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the XOSC32K Ready interrupt flag.
z
Bit 0 – XOSCRDY: XOSC Ready
This flag is cleared by writing a one to it.
This flag is set on a zero-to-one transition of the XOSC Ready bit in the Status register (PCLKSR.XOSCRDY) and
will generate an interrupt request if INTENSET.XOSCRDY is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the XOSC Ready interrupt flag.
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16.8.4 Power and Clocks Status
Name:
PCLKSR
Offset:
0x0C
Reset:
0x00000000
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
B33SRDY
BOD33DET
BOD33RDY
DFLLRCS
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DFLLLCKC
DFLLLCKF
DFLLOOB
DFLLRDY
OSC8MRDY
OSC32KRDY
XOSC32KRDY
XOSCRDY
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bits 31:12 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 11 – B33SRDY: BOD33 Synchronization Ready
0: BOD33 synchronization is complete.
1: BOD33 synchronization is ongoing.
z
Bit 10 – BOD33DET: BOD33 Detection
0: No BOD33 detection.
1: BOD33 has detected that the I/O power supply is going below the BOD33 reference value.
z
Bit 9 – BOD33RDY: BOD33 Ready
0: BOD33 is not ready.
1: BOD33 is ready.
z
Bit 8 – DFLLRCS: DFLL Reference Clock Stopped
0: DFLL reference clock is running.
1: DFLL reference clock has stopped.
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z
Bit 7 – DFLLLCKC: DFLL Lock Coarse
0: No DFLL coarse lock detected.
1: DFLL coarse lock detected.
z
Bit 6 – DFLLLCKF: DFLL Lock Fine
0: No DFLL fine lock detected.
1: DFLL fine lock detected.
z
Bit 5 – DFLLOOB: DFLL Out Of Bounds
0: No DFLL Out Of Bounds detected.
1: DFLL Out Of Bounds detected.
z
Bit 4 – DFLLRDY: DFLL Ready
0: The Synchronization is ongoing.
1: The Synchronization is complete.
This bit is cleared when the synchronization of registers between clock domains is complete.
This bit is set when the synchronization of registers between clock domains is started.
z
Bit 3 – OSC8MRDY: OSC8M Ready
0: OSC8M is not ready.
1: OSC8M is stable and ready to be used as a clock source.
z
Bit 2 – OSC32KRDY: OSC32K Ready
0: OSC32K is not ready.
1: OSC32K is stable and ready to be used as a clock source.
z
Bit 1 – XOSC32KRDY: XOSC32K Ready
0: XOSC32K is not ready.
1: XOSC32K is stable and ready to be used as a clock source.
z
Bit 0 – XOSCRDY: XOSC Ready
0: XOSC is not ready.
1: XOSC is stable and ready to be used as a clock source.
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16.8.5 External Multipurpose Crystal Oscillator (XOSC) Control
Name:
XOSC
Offset:
0x10
Reset:
0x0080
Property:
Write-Protected
Bit
15
14
13
12
STARTUP[3:0]
Access
11
10
AMPGC
9
8
GAIN[2:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ONDEMAND
RUNSTDBY
XTALEN
ENABLE
R/W
R/W
R
R
R
R/W
R/W
R
1
0
0
0
0
0
0
0
Access
Reset
z
Bits 15:12 – STARTUP[3:0]: Start-Up Time
These bits select start-up time for the oscillator according to Table 16-3.
The OSCULP32K oscillator is used to clock the start-up counter.
Table 16-3. Start-UpTime for External Multipurpose Crystal Oscillator
STARTUP[3:0]
Number of OSCULP32K
Clock Cycles (1)
Number of XOSC
Clock Cycles (2)
Approximate Equivalent Time (OSCULP=32.768kHz) (3)
0x0
1
3
31µs
0x1
2
3
61µs
0x2
4
3
122µs
0x3
8
3
244µs
0x4
16
3
488µs
0x5
32
3
977µs
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Table 16-3. Start-UpTime for External Multipurpose Crystal Oscillator
0x6
64
3
1953µs
0x7
128
3
3906µs
0x8
256
3
7813µs
0x9
512
3
15625µs
0xA
1024
3
31250µs
0xB
2048
3
62500µs
0xC
4096
3
125000µs
0xD
8192
3
250000µs
0xE
16384
3
500000µs
0xF
32768
3
1000000µs
Notes:
1.
2.
3.
Number of cycles for the start-up counter.
Number of cycles for the synchronization delay, before PCLKSR.XOSCRDY is set.
Actual start-up time is n OSCULP32K cycles + 3 XOSC cycles, but given the time neglects the 3 XOSC cycles.
z
Bit 11 – AMPGC: Automatic Amplitude Gain Control
0: The automatic amplitude gain control is disabled.
1: The automatic amplitude gain control is enabled. Amplitude gain will be automatically adjusted during Crystal
Oscillator operation.
z
Bits 10:8 – GAIN[2:0]: Oscillator Gain
These bits select the gain for the oscillator, given in table Table 16-4. The listed maximum frequencies are recommendations, and might vary based on capacitive load and crystal characteristics. Setting this bit group has no
effect when the Automatic Amplitude Gain Control is active.
Table 16-4. External Multipurpose Crystal Oscillator Gain Settings
GAIN[2:0]
Recommended Max Frequency
0x0
2MHz
0x1
4MHz
0x2
8MHz
0x3
16MHz
0x4
30MHz
0x5-0x7
Reserved
z
Bit 7 – ONDEMAND: On Demand Control
The On Demand operation mode allows an oscillator to be enabled or disabled, depending on peripheral clock
requests.
In On Demand operation mode, i.e., if the XOSC.ONDEMAND bit has been previously written to one, the oscillator
will be running only when requested by a peripheral. If there is no peripheral requesting the oscillator’s clock
source, the oscillator will be in a disabled state.
If On Demand is disabled, the oscillator will always be running when enabled.
In standby sleep mode, the On Demand operation is still active if the XOSC.RUNSTDBY bit is one. If
XOSC.RUNSTDBY is zero, the oscillator is disabled.
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0: The oscillator is always on, if enabled.
1: The oscillator is enabled when a peripheral is requesting the oscillator to be used as a clock source. The oscillator is disabled if no peripheral is requesting the clock source.
z
Bit 6 – RUNSTDBY: Run in Standby
This bit controls how the XOSC behaves during standby sleep mode:
0: The oscillator is disabled in standby sleep mode.
1: The oscillator is not stopped in standby sleep mode. If XOSC.ONDEMAND is one, the clock source will be running when a peripheral is requesting the clock. If XOSC.ONDEMAND is zero, the clock source will always be
running in standby sleep mode.
z
Bits 5:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – XTALEN: Crystal Oscillator Enable
This bit controls the connections between the I/O pads and the external clock or crystal oscillator:
0: External clock connected on XIN. XOUT can be used as general-purpose I/O.
1: Crystal connected to XIN/XOUT.
z
Bit 1 – ENABLE: Oscillator Enable
0: The oscillator is disabled.
1: The oscillator is enabled.
z
Bit 0 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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16.8.6 32kHz External Crystal Oscillator (XOSC32K) Control
Name:
XOSC32K
Offset:
0x14
Reset:
0x0080
Property:
Write-Protected
Bit
15
14
13
12
11
10
WRTLOCK
9
8
STARTUP[2:0]
Access
R
R
R
R/W
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ONDEMAND
RUNSTDBY
AAMPEN
EN32K
XTALEN
ENABLE
R/W
R/W
R/W
R
R/W
R/W
R/W
R
1
0
0
0
0
0
0
0
Access
Reset
z
Bits 15:13 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 12 – WRTLOCK: Write Lock
This bit locks the XOSC32K register for futur writes to fix the XOSC32K configuration.
0: The XOSC32K configuration is not locked.
1: The XOSC32K configuration is locked.
z
Bit 11 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 10:8 – STARTUP[2:0]: Oscillator Start-Up Time
These bits select the start-up time for the oscillator according to Table 16-5
The OSCULP32K oscillator is used to clock the start-up counter.
Table 16-5. Start-Up Time for 32kHz External Crystal Oscillator
STARTUP[2:0]
Number of OSCULP32K
Clock Cycles (1)
Number of XOSC32K
Clock Cycles (2)
Approximate Equivalent Time
(OSCULP = 32.768kHz) (3)
0x0
1
3
122µs
0x1
32
3
1068µs
0x2
2048
3
62592µs
0x3
4096
3
125092µs
0x4
16384
3
500092µs
0x5
32768
3
1000092µs
0x6
65536
3
2000092µs
0x7
131072
3
4000092µs
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Notes:
z
1.
2.
3.
Number of cycles for the start-up counter.
Number of cycles for the synchronization delay, before PCLKSR.XOSC32KRDY is set.
Start-up time is n OSCULP32K cycles + 3 XOSC32K cycles.
Bit 7 – ONDEMAND: On Demand Control
The On Demand operation mode allows an oscillator to be enabled or disabled depending on peripheral clock
requests.
In On Demand operation mode, i.e., if the ONDEMAND bit has been previously written to one, the oscillator will
only be running when requested by a peripheral. If there is no peripheral requesting the oscillator’s clock source,
the oscillator will be in a disabled state.
If On Demand is disabled the oscillator will always be running when enabled.
In standby sleep mode, the On Demand operation is still active if the XOSC32K.RUNSTDBY bit is one. If
XOSC32K.RUNSTDBY is zero, the oscillator is disabled.
0: The oscillator is always on, if enabled.
1: The oscillator is enabled when a peripheral is requesting the oscillator to be used as a clock source. The oscillator is disabled if no peripheral is requesting the clock source.
z
Bit 6 – RUNSTDBY: Run in Standby
This bit controls how the XOSC32K behaves during standby sleep mode:
0: The oscillator is disabled in standby sleep mode.
1: The oscillator is not stopped in standby sleep mode. If XOSC32K.ONDEMAND is one, the clock source will be
running when a peripheral is requesting the clock. If XOSC32K.ONDEMAND is zero, the clock source will always
be running in standby sleep mode.
z
Bit 5 – AAMPEN: Automatic Amplitude Control Enable
0: The automatic amplitude control for the crystal oscillator is disabled.
1: The automatic amplitude control for the crystal oscillator is enabled.
z
Bit 4 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 3 – EN32K: 32kHz Output Enable
0: The 32kHz output is disabled.
1: The 32kHz output is enabled.
z
Bit 2 – XTALEN: Crystal Oscillator Enable
This bit controls the connections between the I/O pads and the external clock or crystal oscillator:
0: External clock connected on XIN32. XOUT32 can be used as general-purpose I/O.
1: Crystal connected to XIN32/XOUT32.
z
Bit 1 – ENABLE: Oscillator Enable
0: The oscillator is disabled.
1: The oscillator is enabled.
z
Bit 0 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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16.8.7 32kHz Internal Oscillator (OSC32K) Control
Name:
OSC32K
Offset:
0x18
Reset:
0x00000080
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
CALIB[6:0]
Access
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
WRTLOCK
STARTUP[2:0]
Access
R
R
R
R/W
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ONDEMAND
RUNSTDBY
EN32K
ENABLE
R/W
R/W
R
R
R
R/W
R/W
R
1
0
0
0
0
0
0
0
Access
Reset
z
Bits 31:23 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 22:16 – CALIB[6:0]: Oscillator Calibration
These bits control the oscillator calibration.
This value must be written by the user.
Factory calibration values can be loaded from the non-volatile memory. Refer to “NVM Software Calibration Area
Mapping” on page 28.
z
Bits 15:13 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 12 – WRTLOCK: Write Lock
This bit locks the OSC32K register for futur writes to fix the OSC32K configuration.
0: The OSC32K configuration is not locked.
1: The OSC32K configuration is locked.
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z
Bit 11 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 10:8 – STARTUP[2:0]: Oscillator Start-Up Time
These bits select start-up time for the oscillator according to Table 16-6.
The OSCULP32K oscillator is used as input clock to the startup counter.
Table 16-6. Start-Up Time for 32kHz Internal Oscillator
STARTUP[2:0]
Number of OSC32K
clock cycles (1)
Number of OSC32K
clock cycles (2)
Approximate Equivalent Time
(OSCULP= 32.768kHz) (3)
0x0
1
2
92µs
0x1
2
2
122µs
0x2
4
2
183µs
0x3
8
2
305µs
0x4
16
2
549µs
0x5
32
2
1038µs
0x6
64
2
2014µs
0x7
128
2
3967µs
Notes:
z
1.
2.
3.
Number of cycles for the start-up counter.
Number of cycles for the synchronization delay, before PCLKSR.OSC32KRDY is set.
Start-up time is n OSC32K cycles + 2 OSC32K cycles.
Bit 7 – ONDEMAND: On Demand Control
The On Demand operation mode allows an oscillator to be enabled or disabled depending on peripheral clock
requests.
In On Demand operation mode, i.e., if the ONDEMAND bit has been previously written to one, the oscillator will
only be running when requested by a peripheral. If there is no peripheral requesting the oscillator’s clock source,
the oscillator will be in a disabled state.
If On Demand is disabled the oscillator will always be running when enabled.
In standby sleep mode, the On Demand operation is still active if the OSC32K.RUNSTDBY bit is one. If
OSC32K.RUNSTDBY is zero, the oscillator is disabled.
0: The oscillator is always on, if enabled.
1: The oscillator is enabled when a peripheral is requesting the oscillator to be used as a clock source. The oscillator is disabled if no peripheral is requesting the clock source.
z
Bit 6 – RUNSTDBY: Run in Standby
This bit controls how the OSC32K behaves during standby sleep mode:
0: The oscillator is disabled in standby sleep mode.
1: The oscillator is not stopped in standby sleep mode. If OSC32K.ONDEMAND is one, the clock source will be
running when a peripheral is requesting the clock. If OSC32K.ONDEMAND is zero, the clock source will always be
running in standby sleep mode.
z
Bits 5:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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z
Bit 2 – EN32K: 32kHz Output Enable
0: The 32kHz output is disabled.
1: The 32kHz output is enabled.
z
Bit 1 – ENABLE: Oscillator Enable
0: The oscillator is disabled.
1: The oscillator is enabled.
z
Bit 0 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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16.8.8 32kHz Ultra Low Power Internal Oscillator (OSCULP32K) Control
Name:
OSCULP32K
Offset:
0x1C
Reset:
0xXX
Property:
Write-Protected
Bit
7
6
5
4
3
WRTLOCK
Access
Reset
z
2
1
0
CALIB[4:0]
R/W
R
R
R/W
R/W
R/W
R/W
R/W
0
0
0
X
X
X
X
X
Bit 7 – WRTLOCK: Write Lock
This bit locks the OSCULP32K register for future writes to fix the OSCULP32K configuration.
0: The OSCULP32K configuration is not locked.
1: The OSCULP32K configuration is locked.
z
Bits 6:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 4:0 – CALIB[4:0]: Oscillator Calibration
These bits control the oscillator calibration.
These bits are loaded from Flash Calibration at startup.
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16.8.9 8MHz Internal Oscillator (OSC8M) Control
Name:
OSC8M
Offset:
0x20
Reset:
0xXXXX0382
Property:
Write-Protected
Bit
31
30
29
28
27
26
FRANGE[1:0]
Access
25
24
CALIB[11:8]
R/W
R/W
R
R
R/W
R/W
R/W
R/W
Reset
X
X
0
0
X
X
X
X
Bit
23
22
21
20
19
18
17
16
CALIB[7:0]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
X
X
X
X
X
X
X
x
Bit
15
14
13
12
11
10
9
8
PRESC[1:0]
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
1
1
Bit
7
6
5
4
3
2
1
0
ONDEMAND
RUNSTDBY
R/W
R/W
R
R
R
R
R/W
R
1
0
0
0
0
0
1
0
Access
Reset
z
ENABLE
Bits 31:30 – FRANGE[1:0]: Oscillator Frequency Range
These bits control the oscillator frequency range according to Table 16-7.These bits are loaded from Flash Calibration at startup.
Table 16-7. Oscillator Frequency Range
FRANGE[1:0]
Description
0x0
4 to 6MHz
0x1
6 to 8MHz
0x2
8 to 11MHz
0x3
11 to 15MHz
z
Bits 29:28 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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z
Bits 27:16 – CALIB[11:0]: Oscillator Calibration
These bits control the oscillator calibration. The calibration field is split in two:
CALIB[11:6] is for temperature calibration
CALIB[5:0] is for overall process calibration
These bits are loaded from Flash Calibration at startup.
z
Bits 15:10 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 9:8 – PRESC[1:0]: Oscillator Prescaler
These bits select the oscillator prescaler factor setting according to the Table 16-8.
Table 16-8. Oscillator Prescaler
PRESC[1:0]
Description
0x0
1
0x1
2
0x2
4
0x3
8
z
Bit 7 – ONDEMAND: On Demand Control
The On Demand operation mode allows an oscillator to be enabled or disabled depending on peripheral clock
requests.
In On Demand operation mode, i.e., if the ONDEMAND bit has been previously written to one, the oscillator will
only be running when requested by a peripheral. If there is no peripheral requesting the oscillator’s clock source,
the oscillator will be in a disabled state.
If On Demand is disabled the oscillator will always be running when enabled.
In standby sleep mode, the On Demand operation is still active if the OSC8M.RUNSTDBY bit is one. If
OSC8M.RUNSTDBY is zero, the oscillator is disabled.
0: The oscillator is always on, if enabled.
1: The oscillator is enabled when a peripheral is requesting the oscillator to be used as a clock source. The oscillator is disabled if no peripheral is requesting the clock source.
z
Bit 6 – RUNSTDBY: Run in Standby
This bit controls how the OSC8M behaves during standby sleep mode:
0: The oscillator is disabled in standby sleep mode.
1: The oscillator is not stopped in standby sleep mode. If OSC8M.ONDEMAND is one, the clock source will be running when a peripheral is requesting the clock. If OSC8M.ONDEMAND is zero, the clock source will always be
running in standby sleep mode.
z
Bits 5:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – ENABLE: Oscillator Enable
0: The oscillator is disabled or being enabled.
1: The oscillator is enabled or being disabled.
The user must ensure that the OSC8M is fully disabled before enabling it, and that the OSC8M is fully enabled
before disabling it by reading OSC8M.ENABLE.
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z
Bit 0 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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16.8.10 DFLL48M Control
Name:
DFLLCTRL
Offset:
0x24
Reset:
0x0080
Property:
Write-Protected, Write-Synchronized
Bit
15
14
13
12
11
10
9
8
QLDIS
CCDIS
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
LLAW
STABLE
MODE
ENABLE
ONDEMAND
Access
Reset
R/W
R
R
R/W
R/W
R/W
R/W
R
1
0
0
0
0
0
0
0
z
Bits 15:10 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 9 – QLDIS: Quick Lock Disable
0: Quick Lock is enabled.
1: Quick Lock is disabled.
z
Bit 8 – CCDIS: Chill Cycle Disable
0: Chill Cycle is enabled.
1: Chill Cycle is disabled.
z
Bit 7 – ONDEMAND: On Demand Control
The On Demand operation mode allows an oscillator to be enabled or disabled depending on peripheral clock
requests.
In On Demand operation mode, i.e., if the ONDEMAND bit has been previously written to one, the oscillator will
only be running when requested by a peripheral. If there is no peripheral requesting the oscillator’s clock source,
the oscillator will be in a disabled state.
If On Demand is disabled the oscillator will always be running when enabled.
0: The oscillator is always on, if enabled.
1: The oscillator is enabled when a peripheral is requesting the oscillator to be used as a clock source. The oscillator is disabled if no peripheral is requesting the clock source.
z
Bit 6 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 5 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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z
Bit 4 – LLAW: Lose Lock After Wake
0: Locks will not be lost after waking up from sleep modes if the DFLL clock has been stopped.
1: Locks will be lost after waking up from sleep modes if the DFLL clock has been stopped.
z
Bit 3 – STABLE: Stable DFLL Frequency
0: FINE calibration tracks changes in output frequency.
1: FINE calibration register value will be fixed after a fine lock.
z
Bit 2 – MODE: Operating Mode Selection
0: The DFLL operates in open-loop operation.
1: The DFLL operates in closed-loop operation.
z
Bit 1 – ENABLE: DFLL Enable
0: The DFLL oscillator is disabled.
1: The DFLL oscillator is enabled.
Due to synchronization, there is delay from updating the register until the peripheral is enabled/disabled. The value
written to DFLLCTRL.ENABLE will read back immediately after written.
z
Bit 0 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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16.8.11 DFLL48M Value
Name:
DFLLVAL
Offset:
0x28
Reset:
0x00000000
Property:
Write-Protected, Read-Synchronized
Bit
31
30
29
28
27
26
25
24
DIFF[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
DIFF[7:0]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
COARSE[5:0]
FINE[9:8]
Access
R
R
R
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
FINE[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 31:16 – DIFF: Multiplication Ratio Difference
In closed-loop mode (DFLLCTRL.MODE is written to one), this bit group indicates the difference between the ideal
number of DFLL cycles and the counted number of cycles. This value is not updated in open-loop mode, and
should be considered invalid in that case.
z
Bits 15:10 – COARSE: Coarse Value
Set the value of the Coarse Calibration register. In closed-loop mode, this field is read-only.
z
Bits 9:0 – FINE: Fine Value
Set the value of the Fine Calibration register. In closed-loop mode, this field is read-only.
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16.8.12 DFLL48M Multiplier
Name:
DFLLMUL
Offset:
0x2C
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
CSTEP[5:0]
24
FSTEP[9:8]
Access
R
R
R
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
FSTEP[7:0]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
MUL[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
MUL[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 31:26 – CSTEP: Coarse Maximum Step
This bit group indicates the maximum step size allowed during coarse adjustment in closed-loop mode. When
adjusting to a new frequency, the expected output frequency overshoot depends on this step size.
z
Bits 25:16 – FSTEP: Fine Maximum Step
This bit group indicates the maximum step size allowed during fine adjustment in closed-loop mode. When adjusting to a new frequency, the expected output frequency overshoot depends on this step size.
z
Bits 15:0 – MUL: DFLL Multiply Factor
This field determines the ratio of the CLK_DFLL output frequency to the CLK_DFLL_REF input frequency. Writing
to the MUL bits will cause locks to be lost and the fine calibration value to be reset to its midpoint.
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16.8.13 DFLL48M Synchronization
Name:
DFLLSYNC
Offset:
0x30
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
READREQ
Access
W
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bit 7 – READREQ: Read Request
To be able to read the current value of DFLLVAL in closed-loop mode, this bit should be written to one. The
updated value is available in DFLLVAL when PCLKSR.DFLLRDY is set.
z
Bits 6:0 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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16.8.14 3.3V Brown-Out Detector (BOD33) Control
Name:
BOD33
Offset:
0x34
Reset:
0x00XX00XX
Property:
Synchronized, Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
LEVEL[5:0]
Access
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
X
X
X
X
X
X
Bit
15
14
13
12
11
10
9
8
CEN
MODE
PSEL[3:0]
Access
R/W
R/W
R/W
R/W
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
HYST
ENABLE
RUNSTDBY
ACTION[1:0]
Access
R
R/W
R
R/W
R/W
R/W
R/W
R
Reset
0
0
0
X
X
X
X
0
z
Bits 31:22 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 21:16 – LEVEL[5:0]: BOD33 Threshold Level
This field sets the triggering voltage threshold for the BOD33. See the “Electrical Characteristics” on page 571 for
actual voltage levels. Note that any change to the LEVEL field of the BOD33 register should be done when the
BOD33 is disabled in order to avoid spurious resets or interrupts.
These bits are loaded from Flash User Row at startup. Refer to “Non-Volatile Memory (NVM) User Row Mapping”
on page 27 for more details.
z
Bits 15:12 – PSEL[3:0]: Prescaler Select
Selects the prescaler divide-by output for the BOD33 sampling mode, as given in Table 16-9. The input clock
comes from the OSCULP32K 1kHz output.
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Table 16-9. BOD33 Prescaler Select
PSEL[3:0]
Name
Description
0x0
DIV2
Divide clock by 2
0x1
DIV4
Divide clock by 4
0x2
DIV8
Divide clock by 8
0x3
DIV16
Divide clock by 16
0x4
DIV32
Divide clock by 32
0x5
DIV64
Divide clock by 64
0x6
DIV128
Divide clock by 128
0x7
DIV256
Divide clock by 256
0x8
DIV512
Divide clock by 512
0x9
DIV1K
Divide clock by 1024
0xA
DIV2K
Divide clock by 2048
0xB
DIV4K
Divide clock by 4096
0xC
DIV8K
Divide clock by 8192
0xD
DIV16K
Divide clock by 16384
0xE
DIV32K
Divide clock by 32768
0xF
DIV64K
Divide clock by 65536
z
Bits 11:10 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 9 – CEN: Clock Enable
0: The BOD33 sampling clock is either disabled and stopped, or enabled but not yet stable.
1: The BOD33 sampling clock is either enabled and stable, or disabled but not yet stopped.
Writing a zero to this bit will stop the BOD33 sampling clock.
Writing a one to this bit will start the BOD33 sampling clock.
z
Bit 8 – MODE: Operation Mode
0: The BOD33 operates in continuous mode.
1: The BOD33 operates in sampling mode.
z
Bit 7 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 6 – RUNSTDBY: Run in Standby
0: The BOD33 is disabled in standby sleep mode.
1: The BOD33 is enabled in standby sleep mode.
z
Bit 5 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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z
Bits 4:3 – ACTION: BOD33 Action
These bits are used to select the BOD33 action when the supply voltage crosses below the BOD33 threshold, as
shown in Table 16-10.
These bits are loaded from Flash User Row at startup. Refer to “Non-Volatile Memory (NVM) User Row Mapping”
on page 27 for more details.
Table 16-10. BOD33 Action
ACTION[1:0]
Name
Description
0x0
NONE
No action
0x1
RESET
The BOD33 generates a reset
0x2
INTERRUPT
The BOD33 generates an interrupt
0x3
-
Reserved
z
Bit 2 – HYST: Hysteresis
This bit indicates whether hysteresis is enabled for the BOD33 threshold voltage:
0: No hysteresis.
1: Hysteresis enabled.
This bit is loaded from Flash User Row at startup. Refer to “Non-Volatile Memory (NVM) User Row Mapping” on
page 27 for more details.
z
Bit 1 – ENABLE: Enable
0: BOD33 is disabled.
1: BOD33 is enabled.
This bit is loaded from Flash User Row at startup. Refer to “Non-Volatile Memory (NVM) User Row Mapping” on
page 27 for more details.
z
Bit 0 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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16.8.15 Voltage Regulator System (VREG) Control
Name:
VREG
Offset:
0x3C
Reset:
0x0X02
Property:
Write protected
Bit
15
14
13
12
11
10
9
8
FORCELDO
Access
R
R
R/W
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
RUNSTDBY
Access
R
R/W
R
R
R
R
R
R
Reset
0
0
0
0
0
0
1
0
z
Bits 15:14 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 13 – FORCELDO: Force high drive
0: The voltage regulator is in low power and low drive configuration in standby sleep mode.
1: The voltage regulator is in low power and high drive configuration in standby sleep mode.
z
Bits 12:7 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 6 – RUNSTDBY: Run in Standby
0: The voltage regulator is in low power configuration in standby sleep mode.
1: The voltage regulator is in normal configuration in standby sleep mode.
z
Bits 5:0 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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16.8.16 Voltage References System (VREF) Control
Name:
VREF
Offset:
0x40
Reset:
0x0XXX0000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
CALIB[10:8]
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
X
X
X
23
22
21
20
19
18
17
16
Bit
CALIB[7:0]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
X
X
X
X
X
X
X
X
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
BGOUTEN
TSEN
Access
R
R
R
R
R
R/W
R/W
R
Reset
0
0
0
0
0
0
0
0
z
Bits 31:27 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 26:16 – CALIB[10:0]: Bandgap Voltage Generator Calibration
These bits are used to calibrate the output level of the bandgap voltage reference. These bits are loaded from
Flash Calibration Row at startup.
z
Bits 15:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – BGOUTEN: Bandgap Output Enable
0: The bandgap output is not available as an ADC input channel.
1: The bandgap output is routed to an ADC input channel.
z
Bit 1 – TSEN: Temperature Sensor Enable
0: Temperature sensor is disabled.
1: Temperature sensor is enabled and routed to an ADC input channel.
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z
Bit 0 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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17.
WDT – Watchdog Timer
17.1
Overview
The Watchdog Timer (WDT) is a system function for monitoring correct program operation. It makes it possible to recover
from error situations such as runaway or deadlocked code. The WDT is configured to a predefined time-out period, and is
constantly running when enabled. If the WDT is not cleared within the time-out period, it will issue a system reset. An
early-warning interrupt is available to indicate an upcoming watchdog time-out condition.
The window mode makes it possible to define a time slot (or window) inside the total time-out period during which the
WDT must be cleared. If the WDT is cleared outside this window, either too early or too late, a system reset will be
issued. Compared to the normal mode, this can also catch situations where a code error causes the WDT to be cleared
frequently.
When enabled, the WDT will run in active mode and all sleep modes. It is asynchronous and runs from a CPUindependent clock source.The WDT will continue operation and issue a system reset or interrupt even if the main clocks
fail.
17.2
Features
z Issues a system reset if the Watchdog Timer is not cleared before its time-out period
z Early Warning interrupt generation
z Asynchronous operation from dedicated oscillator
z Two types of operation:
z
z
Normal mode
Window mode
z Selectable time-out periods, from 8 cycles to 16,000 cycles in normal mode or 16 cycles to 32,000 cycles in window
mode
z Always-on capability
17.3
Block Diagram
Figure 17-1. WDT Block Diagram
0xA5
0
CLEAR
GCLK_WDT
COUNT
PER/WINDOW/EWOFFSET
Early Warning Interrupt
Reset
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17.4
Signal Description
Not applicable.
17.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
17.5.1 I/O Lines
Not applicable.
17.5.2 Power Management
The WDT can continue to operate in any sleep mode where the selected source clock is running. The WDT interrupts
can be used to wake up the device from sleep modes. The events can trigger other operations in the system without
exiting sleep modes. Refer to “PM – Power Manager” on page 107 for details on the different sleep modes.
17.5.3 Clocks
The WDT bus clock (CLK_WDT_APB) is enabled by default, and can be enabled and disabled in the Power Manager.
Refer to “PM – Power Manager” on page 107 for details.
A generic clock (GCLK_WDT) is required to clock the WDT. This clock must be configured and enabled in the Generic
Clock Controller before using the WDT. Refer to “GCLK – Generic Clock Controller” on page 85 for details.
This generic clock is asynchronous to the user interface clock (CLK_WDT_APB). Due to this asynchronicity, accessing
certain registers will require synchronization between the clock domains. Refer to “Synchronization” on page 190 for
further details.
GCLK_WDT is intended to be sourced from the clock of the internal ultra-low-power (ULP) oscillator. Due to the ultralow-power design, the oscillator is not very accurate, and so the exact time-out period may vary from device to device.
This variation must be kept in mind when designing software that uses the WDT to ensure that the time-out periods used
are valid for all devices. For more information on ULP oscillator accuracy, consult the “Ultra Low Power Internal 32kHz
RC Oscillator (OSCULP32K) Characteristics” on page 600.
GCLK_WDT can also be clocked from other sources if a more accurate clock is needed, but at the cost of higher power
consumption.
17.5.4 DMA
Not applicable.
17.5.5 Interrupts
The interrupt request line is connected to the Interrupt Controller. Using the WDT interrupts requires the interrupt
controller to be configured first. Refer to “Nested Vector Interrupt Controller” on page 30 for details.
17.5.6 Events
Not applicable.
17.5.7 Debug Operation
When the CPU is halted in debug mode, the WDT will halt normal operation. If the WDT is configured in a way that
requires it to be periodically serviced by the CPU through interrupts or similar, improper operation or data loss may result
during debugging. The WDT can be forced to halt operation during debugging.
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17.5.8 Register Access Protection
All registers with write-access are optionally write-protected by the peripheral access controller (PAC), except the
following registers:
z
Interrupt Flag Status and Clear register (INTFLAG - refer to INTFLAG)
Write-protection is denoted by the Write-Protection property in the register description.
When the CPU is halted in debug mode, all write-protection is automatically disabled.
Write-protection does not apply for accesses through an external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
17.5.9 Analog Connections
Not applicable.
17.6
Functional Description
17.6.1 Principle of Operation
The Watchdog Timer (WDT) is a system for monitoring correct program operation, making it possible to recover from
error situations such as runaway code by issuing a reset. When enabled, the WDT is a constantly running timer that is
configured to a predefined time-out period. Before the end of the time-out period, the WDT should be reconfigured.
The WDT has two modes of operation, normal and window. Additionally, the user can enable Early Warning interrupt
generation in each of the modes. The description for each of the basic modes is given below. The settings in the Control
register (CTRL - refer to CTRL) and the Interrupt Enable register (INTENCLR/SET - refer to INTENCLR) determine the
mode of operation, as illustrated in Table 17-1.
Table 17-1. WDT Operating Modes
ENABLE
WEN
Interrupt
Enable
0
x
x
Stopped
1
0
0
Normal
1
0
1
Normal with Early Warning interrupt
1
1
0
Window
1
1
1
Window with Early Warning interrupt
Mode
17.6.2 Basic Operation
17.6.2.1 Initialization
The following registers are enable-protected:
z
Control register (CTRL - refer to CTRL), except the Enable bit (CTRL.ENABLE)
z
Configuration register (CONFIG - refer to CONFIG)
z
Early Warning Interrupt Control register (EWCTRL - refer to EWCTRL)
Any writes to these bits or registers when the WDT is enabled or is being enabled (CTRL.ENABLE is one) will be
discarded. Writes to these registers while the WDT is being disabled will be completed after the disabling is complete.
Enable-protection is denoted by the Enable-Protected property in the register description.
Initialization of the WDT can be done only while the WDT is disabled. The WDT is configured by defining the required
Time-Out Period bits in the Configuration register (CONFIG.PER). If window-mode operation is required, the Window
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Enable bit in the Control register (CTRL.WEN) must be written to one and the Window Period bits in the Configuration
register (CONFIG.WINDOW) must be defined.
17.6.2.2 Configurable Reset Values
On a power-on reset, some registers will be loaded with initial values from the NVM User Row. Refer to “Non-Volatile
Memory (NVM) User Row Mapping” on page 27 for more details.
This encompasses the following bits and bit groups:
z
Enable bit in the Control register (CTRL.ENABLE)
z
Always-On bit in the Control register (CTRL.ALWAYSON)
z
Watchdog Timer Windows Mode Enable bit in the Control register (CTRL.WEN)
z
Watchdog Timer Windows Mode Time-Out Period bits in the Configuration register (CONFIG.WINDOW)
z
Time-Out Period in the Configuration register (CONFIG.PER)
z
Early Warning Interrupt Time Offset bits in the Early Warning Interrupt Control register (EWCTRL.EWOFFSET)
For more information about fuse locations, see “Non-Volatile Memory (NVM) User Row Mapping” on page 27.
17.6.2.3 Enabling and Disabling
The WDT is enabled by writing a one to the Enable bit in the Control register (CTRL.ENABLE). The WDT is disabled by
writing a zero to CTRL.ENABLE.
The WDT can be disabled only while the Always-On bit in the Control register (CTRL.ALWAYSON) is zero.
17.6.2.4 Normal Mode
In normal-mode operation, the length of a time-out period is configured in CONFIG.PER. The WDT is enabled by writing
a one to the Enable bit in the Control register (CTRL.ENABLE). Once enabled, if the WDT is not cleared from the
application code before the time-out occurs, the WDT will issue a system reset. There are 12 possible WDT time-out
(TOWDT) periods, selectable from 8ms to 16s, and the WDT can be cleared at any time during the time-out period. A new
WDT time-out period will be started each time the WDT is cleared by writing 0xA5 to the Clear register (CLEAR - refer to
CLEAR). Writing any value other than 0xA5 to CLEAR will issue an immediate system reset.
By default, WDT issues a system reset upon a time-out, and the early warning interrupt is disabled. If an early warning
interrupt is required, the Early Warning Interrupt Enable bit in the Interrupt Enable register (INTENSET.EW) must be
enabled. Writing a one to the Early Warning Interrupt bit in the Interrupt Enable Set register (INTENSET.EW) enables the
interrupt, and writing a one to the Early Warning Interrupt bit in the Interrupt Enable Clear register (INTENCLR.EW)
disables the interrupt. If the Early Warning Interrupt is enabled, an interrupt is generated prior to a watchdog time-out
condition. In normal mode, the Early Warning Offset bits in the Early Warning Interrupt Control register
(EWCTRL.EWOFFSET) define the time where the early warning interrupt occurs. The normal-mode operation is
illustrated in Figure 17-2.
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Figure 17-2. Normal-Mode Operation
System Reset
WDT Count
Timely WDT Clear
PER[3:0]=1
WDT Timeout
Early Warning Interrupt
EWOFFSET[3:0]=0
5
10
15
20
25
30
TOWDT
35
t [ms]
17.6.2.5 Window Mode
In window-mode operation, the WDT uses two different time-out periods, a closed window time-out period (TOWDTW) and
the normal, or open, time-out period (TOWDT). The closed window time-out period defines a duration from 8ms to 16s
where the WDT cannot be reset. If the WDT is cleared during this period, the WDT will issue a system reset. The normal
WDT time-out period, which is also from 8ms to 16s, defines the duration of the open period during which the WDT can
be cleared. The open period will always follow the closed period, and so the total duration of the time-out period is the
sum of the closed window and the open window time-out periods. The closed window is defined by the Window Period
bits in the Configuration register (CONFIG.WINDOW), and the open window is defined by the Period bits in the
Configuration register (CONFIG.PER).
By default, the WDT issues a system reset upon a time-out and the Early Warning interrupt is disabled. If an Early
Warning interrupt is required, INTENCLR/SET.EW must be set. Writing a one to INTENSET.EW enables the interrupt,
and writing a one to INTENCLR.EW disables the interrupt. If the Early Warning interrupt is enabled in window mode, the
interrupt is generated at the start of the open window period.
The window mode operation is illustrated in Figure 17-3.
Figure 17-3. Window-Mode Operation
WDT Count
Timely WDT Clear
Open
PER[3:0]=0
Early Warning Interrupt
Early WDT Clear
Closed
WINDOW[3:0]=0
WDT Timeout
5
10
15
20
TOWDTW
25
30
TOWDT
35
t [ms]
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17.6.3 Additional Features
17.6.3.1 Always-On Mode
The always-on mode is enabled by writing a one to the Always-On bit in the Control register (CTRL.ALWAYSON). When
the always-on mode is enabled, the WDT runs continuously, regardless of the state of CTRL.ENABLE. Once written, the
Always-On bit can only be cleared by a power-on reset. The Configuration (CONFIG) and Early Warning Control
(EWCTRL) registers are read-only registers while the CTRL.ALWAYSON bit is set. Thus, the time period configuration
bits (CONFIG.PER, CONFIG.WINDOW, EWCTRL.EWOFFSET) of the WDT cannot be changed.
Enabling or disabling window-mode operation by writing the Window Enable bit (CTRL.WEN) is allowed while in the
always-on mode, but note that CONFIG.PER cannot be changed.
The CTRL.ALWAYSON bit must never be set to one by software if any of the following conditions is true:
a.
The GCLK_WDT is disabled
b.
The clock generator for the GCLK_WDT is disabled
c.
The source clock of the clock generator for the GCLK_WDT is disabled or off
The Interrupt Clear and Interrupt Set registers are accessible in the always-on mode. The Early Warning interrupt can still
be enabled or disabled while in the always-on mode, but note that EWCTRL.EWOFFSET cannot be changed.
Table 17-2 shows the operation of the WDT when CTRL.ALWAYSON is set.
Table 17-2. WDT Operating Modes With Always-On
WEN
Interrupt enable
Mode
0
0
Always-on and normal mode
0
1
Always-on and normal mode with Early Warning interrupt
1
0
Always-on and window mode
1
1
Always-on and window mode with Early Warning interrupt
17.6.4 Interrupts
The WDT has the following interrupt sources:
z
Early Warning (EW): this is an asynchronous interrupt and can be used to wake-up the device from any sleep
mode.
Each interrupt source has an interrupt flag associated with it. The interrupt flag in the Interrupt Flag Status and Clear
register (INTFLAG) is set when the interrupt condition occurs. Each interrupt can be individually enabled by writing a one
to the corresponding bit in the Interrupt Enable Set register (INTENSET), and disabled by writing a one to the
corresponding bit in the Interrupt Enable Clear register (INTENCLR). An interrupt request is generated when the interrupt
flag is set and the corresponding interrupt is enabled. The interrupt request remains active until the interrupt flag is
cleared, the interrupt is disabled or the WDT is reset. See INTFLAG for details on how to clear interrupt flags.
The WDT has one common interrupt request line for all the interrupt sources. The user must read INTFLAG to determine
which interrupt condition is present.
Note that interrupts must be globally enabled for interrupt requests to be generated. Refer to “Nested Vector Interrupt
Controller” on page 30 for details.
The Early Warning interrupt behaves differently in normal mode and in window mode. In normal mode, the Early Warning
interrupt generation is defined by the Early Warning Offset in the Early Warning Control register (EWCTRL.EWOFFSET).
The Early Warning Offset bits define the number of GCLK_WDT clocks before the interrupt is generated, relative to the
start of the watchdog time-out period. For example, if the WDT is operating in normal mode with CONFIG.PER = 0x2 and
EWCTRL.EWOFFSET = 0x1, the Early Warning interrupt is generated 16 GCLK_WDT clock cycles from the start of the
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watchdog time-out period, and the watchdog time-out system reset is generated 32 GCLK_WDT clock cycles from the
start of the watchdog time-out period. The user must take caution when programming the Early Warning Offset bits. If
these bits define an Early Warning interrupt generation time greater than the watchdog time-out period, the watchdog
time-out system reset is generated prior to the Early Warning interrupt. Thus, the Early Warning interrupt will never be
generated.
In window mode, the Early Warning interrupt is generated at the start of the open window period. In a typical application
where the system is in sleep mode, it can use this interrupt to wake up and clear the Watchdog Timer, after which the
system can perform other tasks or return to sleep mode.
17.6.5 Synchronization
Due to the asynchronicity between CLK_WDT_APB and GCLK_WDT some registers must be synchronized when
accessed. A register can require:
z
Synchronization when written
z
Synchronization when read
z
Synchronization when written and read
z
No synchronization
When executing an operation that requires synchronization, the Synchronization Busy bit in the Status
register(STATUS.SYNCBUSY) will be set immediately, and cleared when synchronization is complete. The
synchronization Ready interrupt can be used to signal when sync is complete. This can be accessed via the
Synchronization Ready Interrupt Flag in the Interrupt Flag Status and Clear register (INTFLAG.SYNCRDY).
If an operation that requires synchronization is executed while STATUS.SYNCBUSY is one, the bus will be stalled. All
operations will complete successfully, but the CPU will be stalled and interrupts will be pending as long as the bus is
stalled.
The following registers need synchronization when written:
z
Control register (CTRL)
z
Clear register (CLEAR)
Write-synchronization is denoted by the Write-Synchronized property in the register description.
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17.7
Register Summary
Register summary
Offset
Name
Bit
Pos.
0x0
CTRL
7:0
0x1
CONFIG
7:0
0x2
EWCTRL
7:0
0x3
Reserved
0x4
INTENCLR
7:0
EW
0x5
INTENSET
7:0
EW
0x6
INTFLAG
7:0
EW
0x7
STATUS
7:0
0x8
CLEAR
7:0
ALWAYSON
WEN
WINDOW[3:0]
ENABLE
PER[3:0]
EWOFFSET[3:0]
SYNCBUSY
CLEAR[7:0]
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17.8
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-Protected property in each individual register description. Refer to “Register Access Protection” on page 186
for details.
Some registers require synchronization when read and/or written. Synchronization is denoted by the Write-Synchronized
or the Read-Synchronized property in each individual register description. Refer to “Synchronization” on page 190 for
details.
Some registers are enable-protected, meaning they can be written only when the WDT is disabled. Enable-protection is
denoted by the Enable-Protected property in each individual register description.
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17.8.1 Control
Name:
CTRL
Offset:
0x0
Reset:
N/A - Loaded from NVM User Row at startup
Property:
Write-Protected, Enable-Protected, Write-Synchronized
Bit
7
6
5
4
3
ALWAYSON
Access
Reset
z
2
1
WEN
ENABLE
0
R/W1
R/W
R/W
R/W
R/W
R/W
R/W
R/W
X
0
0
0
0
X
X
0
Bit 7 – ALWAYSON: Always-On
This bit allows the WDT to run continuously. After being written to one, this bit cannot be written to zero, and the
WDT will remain enabled until a power-on reset is received. When this bit is one, the Control register (CTRL), the
Configuration register (CONFIG) and the Early Warning Control register (EWCTRL) will be read-only, and any
writes to these registers are not allowed. Writing a zero to this bit has no effect.
0: The WDT is enabled and disabled through the ENABLE bit.
1: The WDT is enabled and can only be disabled by a power-on reset (POR).
This bit is not enable-protected.
These bits are loaded from NVM User Row at startup. Refer to “Non-Volatile Memory (NVM) User Row Mapping”
on page 27 for more details.
z
Bits 6:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – WEN: Watchdog Timer Window Mode Enable
The initial value of this bit is loaded from Flash Calibration.
0: Window mode is disabled (normal operation).
1: Window mode is enabled.
This bit is loaded from NVM User Row at startup. Refer to “Non-Volatile Memory (NVM) User Row Mapping” on
page 27 for more details.
z
Bit 1 – ENABLE: Enable
This bit enables or disables the WDT. Can only be written while CTRL.ALWAYSON is zero.
0: The WDT is disabled.
1: The WDT is enabled.
Due to synchronization, there is delay from writing CTRL.ENABLE until the peripheral is enabled/disabled. The
value written to CTRL.ENABLE will read back immediately, and the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set. STATUS.SYNCBUSY will be cleared when the operation is complete.
This bit is not enable-protected.
This bit is loaded from NVM User Row at startup. Refer to “Non-Volatile Memory (NVM) User Row Mapping” on
page 27 for more details.
z
Bit 0 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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17.8.2 Configuration
Name:
CONFIG
Offset:
0x1
Reset:
N/A - Loaded from NVM User Row at startup
Property:
Write-Protected, Enable-Protected, Write-Synchronized
Bit
7
6
5
4
3
2
WINDOW[3:0]
Access
Reset
z
1
0
PER[3:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
X
X
X
X
X
X
X
X
Bits 7:4 – WINDOW[3:0]: Window Mode Time-Out Period
In window mode, these bits determine the watchdog closed window period as a number of oscillator cycles. The
closed window periods are defined in Table 17-3.
These bits are loaded from NVM User Row at startup. Refer to “Non-Volatile Memory (NVM) User Row Mapping”
on page 27 for more details.
Table 17-3. Window Mode Time-Out Period
Value
0x0
8 clock cycles
0x1
16 clock cycles
0x2
32 clock cycles
0x3
64 clock cycles
0x4
128 clock cycles
0x5
256 clocks cycles
0x6
512 clocks cycles
0x7
1024 clock cycles
0x8
2048 clock cycles
0x9
4096 clock cycles
0xA
8192 clock cycles
0xB
16384 clock cycles
0xC-0xF
z
Description
Reserved
Bits 3:0 – PER[3:0]: Time-Out Period
These bits determine the watchdog time-out period as a number of GCLK_WDT clock cycles. In window mode
operation, these bits define the open window period. The different typical time-out periods are found in Table 17-4.
These bits are loaded from NVM User Row at startup. Refer to “Non-Volatile Memory (NVM) User Row Mapping”
on page 27 for more details.
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Table 17-4. Time-Out Period
Value
Description
0x0
8 clock cycles
0x1
16 clock cycles
0x2
32 clock cycles
0x3
64 clock cycles
0x4
128 clock cycles
0x5
256 clocks cycles
0x6
512 clocks cycles
0x7
1024 clock cycles
0x8
2048 clock cycles
0x9
4096 clock cycles
0xA
8192 clock cycles
0xB
16384 clock cycles
0xC-0xF
Reserved
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17.8.3 Early Warning Interrupt Control
Name:
EWCTRL
Offset:
0x2
Reset:
N/A - Loaded from NVM User Row at startup
Property:
Write-Protected, Enable-Protected
Bit
7
6
5
4
3
2
1
0
EWOFFSET[3:0]
Acces
s
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
X
X
X
X
z
Bits 7:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 3:0 – EWOFFSET[3:0]: Early Warning Interrupt Time Offset
These bits determine the number of GCLK_WDT clocks in the offset from the start of the watchdog time-out period
to when the Early Warning interrupt is generated. The Early Warning Offset is defined in Table 17-5. These bits
are loaded from NVM User Row at startup. Refer to “Non-Volatile Memory (NVM) User Row Mapping” on page 27
for more details.
Table 17-5. Early Warning Interrupt Time Offset
Value
Description
0x0
8 clock cycles
0x1
16 clock cycles
0x2
32 clock cycles
0x3
64 clock cycles
0x4
128 clock cycles
0x5
256 clocks cycles
0x6
512 clocks cycles
0x7
1024 clock cycles
0x8
2048 clock cycles
0x9
4096 clock cycles
0xA
8192 clock cycles
0xB
16384 clock cycles
0xC-0xF
Reserved
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17.8.4 Interrupt Enable Clear
This register allows the user to disable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Set register (INTENSET).
Name:
INTENCLR
Offset:
0x4
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
EW
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – EW: Early Warning Interrupt Enable
0: The Early Warning interrupt is disabled.
1: The Early Warning interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit disables the Early Warning interrupt.
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17.8.5 Interrupt Enable Set
This register allows the user to enable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Clear register (INTENCLR).
Name:
INTENSET
Offset:
0x5
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
EW
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – EW: Early Warning Interrupt Enable
0: The Early Warning interrupt is disabled.
1: The Early Warning interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit enables the Early Warning interrupt.
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17.8.6 Interrupt Flag Status and Clear
Name:
INTFLAG
Offset:
0x6
Reset:
0x00
Property:
–
Bit
7
6
5
4
3
2
1
0
EW
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these
bits to zero when this register is written. These bits will always return zero when read.
z
Bit 0 – EW: Early Warning
This flag is set when an Early Warning interrupt occurs, as defined by the EWOFFSET bit group in
EWCTRL.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Early Warning interrupt flag.
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17.8.7 Status
Name:
STATUS
Offset:
0x7
Reset:
0x00
Property:
–
Bit
7
6
5
4
3
2
1
0
SYNCBUSY
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bit 7 – SYNCBUSY: Synchronization Busy
This bit is cleared when the synchronization of registers between clock domains is complete.
This bit is set when the synchronization of registers between clock domains is started.
z
Bits 6:0 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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17.8.8 Clear
Name:
CLEAR
Offset:
Offset: 0x8
Reset:
0x00
Property:
Write-Protected, Write-Synchronized
Bit
7
6
5
4
3
2
1
0
CLEAR[7:0]
Access
W
W
W
W
W
W
W
W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:0 – CLEAR: Watchdog Clear
Writing 0xA5 to this register will clear the Watchdog Timer and the watchdog time-out period is restarted. Writing
any other value will issue an immediate system reset.
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18.
18.1
RTC – Real-Time Counter
Overview
The Real-Time Counter (RTC) is a 32-bit counter with a 10-bit programmable prescaler that typically runs continuously to
keep track of time. The RTC can wake up the device from sleep modes using the alarm/compare wake up, periodic wake
up or overflow wake up mechanisms.
The RTC can generate periodic peripheral events from outputs of the prescaler, as well as alarm/compare interrupts and
peripheral events, which can trigger at any counter value. Additionally, the timer can trigger an overflow interrupt and
peripheral event, and be reset on the occurrence of an alarm/compare match. This allows periodic interrupts and
peripheral events at very long and accurate intervals.
The 10-bit programmable prescaler can scale down the clock source, and so a wide range of resolutions and time-out
periods can be configured. With a 32.768kHz clock source, the minimum counter tick interval is 30.5µs, and time-out
periods can range up to 36 hours. With the counter tick interval configured to 1s, the maximum time-out period is more
than 136 years.
18.2
Features
z 32-bit counter with 10-bit prescaler
z Multiple clock sources
z 32-bit or 16-bit Counter mode
z
One 32-bit or two 16-bit compare values
z Clock/Calendar mode
z
Time in seconds, minutes and hours (12/24)
Date in day of month, month and year
z Leap year correction
z
z Digital prescaler correction/tuning for increased accuracy
z Overflow, alarm/compare match and prescaler interrupts and events
z
18.3
Optional clear on alarm/compare match
Block Diagram
Figure 18-1. RTC Block Diagram (Mode 0 — 32-Bit Counter)
0
MATCHCLR
GCLK_RTC
10-bit
Prescaler
CLK_RTC_CNT
Overflow
COUNT
32
=
Periodic
Events
Compare n
32
COMPn
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Figure 18-2. RTC Block Diagram (Mode 1 — 16-Bit Counter)
0
GCLK_RTC
10-bit
Prescaler
CLK_RTC_CNT
COUNT
=
16
Overflow
16
Periodic
Events
PER
=
Compare n
16
COMPn
Figure 18-3. RTC Block Diagram (Mode 2 — Clock/Calendar)
0
MATCHCLR
GCLK_RTC
10-bit
Prescaler
CLK_RTC_CNT
32
Y/M/D H:M:S
32
Y/M/D H:M:S
=
MASKn
Periodic
Events
18.4
Overflow
CLOCK
Alarm n
ALARMn
Signal Description
Not applicable.
18.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
18.5.1 I/O Lines
Not applicable.
18.5.2 Power Management
The RTC can continue to operate in any sleep mode. The RTC interrupts can be used to wake up the device from sleep
modes. The events can trigger other operations in the system without exiting sleep modes. Refer to “PM – Power
Manager” on page 107 for details on the different sleep modes.
The RTC will be reset only at power-on (POR) or by writing a one to the Software Reset bit in the Control register
(CTRL.SWRST).
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18.5.3 Clocks
The RTC bus clock (CLK_RTC_APB) can be enabled and disabled in the Power Manager, and the default state of
CLK_RTC_APB can be found in the Peripheral Clock Masking section in the “PM – Power Manager” on page 107.
A generic clock (GCLK_RTC) is required to clock the RTC. This clock must be configured and enabled in the Generic
Clock Controller before using the RTC. Refer to “GCLK – Generic Clock Controller” on page 85 for details.
This generic clock is asynchronous to the user interface clock (CLK_RTC_APB). Due to this asynchronicity, accessing
certain registers will require synchronization between the clock domains. Refer to “Synchronization” on page 209 for
further details.
The RTC should never be used with the generic clock generator 0.
18.5.4 DMA
Not applicable.
18.5.5 Interrupts
The interrupt request line is connected to the Interrupt Controller. Using the RTC interrupts requires the interrupt
controller to be configured first. Refer to “Nested Vector Interrupt Controller” on page 30 for details.
18.5.6 Events
To use the RTC event functionality, the corresponding events need to be configured in the event system. Refer to
“EVSYS – Event System” on page 313 for details.
18.5.7 Debug Operation
When the CPU is halted in debug mode the RTC will halt normal operation. The RTC can be forced to continue operation
during debugging. Refer to the DBGCTRL register for details.
18.5.8 Register Access Protection
All registers with write-access are optionally write-protected by the peripheral access controller (PAC), except the
following registers:
z
Interrupt Flag Status and Clear register (INTFLAG - refer to INTFLAG)
z
Read Request register (READREQ - refer to READREQ)
z
Status register (STATUS - refer to STATUS)
z
Debug register (DBGCTRL - refer to DBGCTRL)
Write-protection is denoted by the Write-Protection property in the register description.
When the CPU is halted in debug mode, all write-protection is automatically disabled.
Write-protection does not apply for accesses through an external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
18.5.9 Analog Connections
A 32.768kHz crystal can be connected to the XIN32 and XOUT32 pins, along with any required load capacitors. For
details on recommended crystal characteristics and load capacitors, refer to “Electrical Characteristics” on page 571 for
details.
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18.6
Functional Description
18.6.1 Principle of Operation
The RTC keeps track of time in the system and enables periodic events, as well as interrupts and events at a specified
time. The RTC consists of a 10-bit prescaler that feeds a 32-bit counter. The actual format of the 32-bit counter depends
on the RTC operating mode.
18.6.2 Basic Operation
18.6.2.1 Initialization
The following bits are enable-protected, meaning that they can only be written when the RTC is disabled (CTRL.ENABLE
is zero):
z
Operating Mode bits in the Control register (CTRL.MODE)
z
Prescaler bits in the Control register (CTRL.PRESCALER)
z
Clear on Match bit in the Control register (CTRL.MATCHCLR)
z
Clock Representation bit in the Control register (CTRL.CLKREP)
The following register is enable-protected:
z
Event Control register (EVCTRL - refer to EVCTRL)
Any writes to these bits or registers when the RTC is enabled or being disabled (CTRL.ENABLE is one) will be discarded.
Writes to these bits or registers while the RTC is being disabled will be completed after the disabling is complete.
Enable-protection is denoted by the Enable-Protection property in the register description.
Before the RTC is enabled, it must be configured, as outlined by the following steps:
z
RTC operation mode must be selected by writing the Operating Mode bit group in the Control register
(CTRL.MODE)
z
Clock representation must be selected by writing the Clock Representation bit in the Control register
(CTRL.CLKREP)
z
Prescaler value must be selected by writing the Prescaler bit group in the Control register (CTRL.PRESCALER)
The RTC prescaler divides down the source clock for the RTC counter. The frequency of the RTC clock
(CLK_RTC_CNT) is given by the following formula:
f GCLK_RTC
f CLK_RTC_CNT = ---------------------------PRESCALER
2
The frequency of the generic clock, GCLK_RTC, is given by fGCLK_RTC, and fCLK_RTC_CNT is the frequency of the internal
prescaled RTC clock, CLK_RTC_CNT.
Note that in the Clock/Calendar mode, the prescaler must be configured to provide a 1Hz clock to the counter for correct
operation.
18.6.2.2 Enabling, Disabling and Resetting
The RTC is enabled by writing a one to the Enable bit in the Control register (CTRL.ENABLE). The RTC is disabled by
writing a zero to CTRL.ENABLE.
The RTC should be disabled before resetting it.
The RTC is reset by writing a one to the Software Reset bit in the Control register (CTRL.SWRST). All registers in the
RTC, except DBGCTRL, will be reset to their initial state, and the RTC will be disabled.
Refer to the CTRL register for details.
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18.6.3 Operating Modes
The RTC counter supports three RTC operating modes: 32-bit Counter, 16-bit Counter and Clock/Calendar. The
operating mode is selected by the Operating Mode bit group in the Control register (CTRL.MODE).
18.6.3.1 32-Bit Counter (Mode 0)
When the RTC Operating Mode bits in the Control register (CTRL.MODE) are zero, the counter operates in 32-bit
Counter mode. The block diagram of this mode is shown in Figure 18-1. When the RTC is enabled, the counter will
increment on every 0-to-1 transition of CLK_RTC_CNT. The counter will increment until it reaches the top value of
0xFFFFFFFF, and then wrap to 0x00000000. This sets the Overflow Interrupt flag in the Interrupt Flag Status and Clear
register (INTFLAG.OVF).
The RTC counter value can be read from or written to the Counter Value register (COUNT) in 32-bit format.
The counter value is continuously compared with the 32-bit Compare register (COMP0). When a compare match occurs,
the Compare 0Interrupt flag in the Interrupt Flag Status and Clear register (INTFLAG.CMP0) is set on the next 0-to-1
transition of CLK_RTC_CNT.
If the Clear on Match bit in the Control register (CTRL.MATCHCLR) is one, the counter is cleared on the next counter
cycle when a compare match with COMP0 occurs. This allows the RTC to generate periodic interrupts or events with
longer periods than are possible with the prescaler events. Note that when CTRL.MATCHCLR is one, INTFLAG.CMP0
and INTFLAG.OVF will both be set simultaneously on a compare match with COMP0.
18.6.3.2 16-Bit Counter (Mode 1)
When CTRL.MODE is one, the counter operates in 16-bit Counter mode as shown in Figure 18-2. When the RTC is
enabled, the counter will increment on every 0-to-1 transition of CLK_RTC_CNT. In 16-bit Counter mode, the 16-bit
Period register (PER) holds the maximum value of the counter. The counter will increment until it reaches the PER value,
and then wrap to 0x0000. This sets the Overflow Interrupt flag in the Interrupt Flag Status and Clear register
(INTFLAG.OVF).
The RTC counter value can be read from or written to the Counter Value register (COUNT) in 16-bit format.
The counter value is continuously compared with the 16-bit Compare registers (COMPn, n=0–1). When a compare
match occurs, the Compare n Interrupt flag in the Interrupt Flag Status and Clear register (INTFLAG.CMPn, n=0–1) is set
on the next 0-to-1 transition of CLK_RTC_CNT.
18.6.3.3 Clock/Calendar (Mode 2)
When CTRL.MODE is two, the counter operates in Clock/Calendar mode, as shown in Figure 18-3. When the RTC is
enabled, the counter will increment on every 0-to-1 transition of CLK_RTC_CNT. The selected clock source and RTC
prescaler must be configured to provide a 1Hz clock to the counter for correct operation in this mode.
The time and date can be read from or written to the Clock Value register (CLOCK) in a 32-bit time/date format. Time is
represented as:
z
Seconds
z
Minutes
z
Hours
Hours can be represented in either 12- or 24-hour format, selected by the Clock Representation bit in the Control register
(CTRL.CLKREP). This bit can be changed only while the RTC is disabled.
Date is represented as:
z
Day as the numeric day of the month (starting at 1)
z
Month as the numeric month of the year (1 = January, 2 = February, etc.)
z
Year as a value counting the offset from a reference value that must be defined in software
The date is automatically adjusted for leap years, assuming every year divisible by 4 is a leap year. Therefore, the
reference value must be a leap year, e.g. 2000. The RTC will increment until it reaches the top value of 23:59:59
December 31 of year 63, and then wrap to 00:00:00 January 1 of year 0. This will set the Overflow Interrupt flag in the
Interrupt Flag Status and Clear registers (INTFLAG.OVF).
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The clock value is continuously compared with the 32-bit Alarm register (ALARM0). When an alarm match occurs, the
Alarm 0 Interrupt flag in the Interrupt Flag Status and Clear registers (INTFLAG.ALARMn0) is set on the next 0-to-1
transition of CLK_RTC_CNT.
A valid alarm match depends on the setting of the Alarm Mask Selection bits in the Alarm 0 Mask register (MASK0.SEL).
These bits determine which time/date fields of the clock and alarm values are valid for comparison and which are
ignored.
If the Clear on Match bit in the Control register (CTRL.MATCHCLR) is one, the counter is cleared on the next counter
cycle when an alarm match with ALARM0 occurs. This allows the RTC to generate periodic interrupts or events with
longer periods than are possible with the prescaler events (see “Periodic Events” on page 207). Note that when
CTRL.MATCHCLR is one, INTFLAG.ALARM0 and INTFLAG.OVF will both be set simultaneously on an alarm match
with ALARM0.
18.6.4 Additional Features
18.6.4.1 Periodic Events
The RTC prescaler can generate events at periodic intervals, allowing flexible system tick creation. Any of the upper
eight bits of the prescaler (bits 2 to 9) can be the source of an event. When one of the Periodic Event Output bits in the
Event Control register (EVCTRL.PEREOn) is one, an event is generated on the 0-to1 transition of the related bit in the
prescaler, resulting in a periodic event frequency of:
f PERIODIC =
f GCLK _ RTC
2 n +3
fGCLK_RTC is the frequency of the internal prescaler clock, GCLK_RTC, and n is the position of the EVCTRL.PEREOn bit.
For example, PER0 will generate an event every 8 GCLK_RTC cycles, PER1 every 16 cycles, etc. This is shown in
Figure 18-4. Periodic events are independent of the prescaler setting used by the RTC counter, except if
CTRL.PRESCALER is zero. Then, no periodic events will be generated.
Figure 18-4. Example Periodic Events
GCLK_RTC
PER0
PER1
PER2
PER3
PER4
18.6.4.2 Frequency Correction
The RTC Frequency Correction module employs periodic counter corrections to compensate for a too-slow or too-fast
oscillator. Frequency correction requires that CTRL.PRESCALER is greater than 1.
The digital correction circuit adds or subtracts cycles from the RTC prescaler to adjust the frequency in approximately
1PPM steps. Digital correction is achieved by adding or skipping a single count in the prescaler once every 1024
GCLK_RTC cycles. The Value bit group in the Frequency Correction register (FREQCORR.VALUE) determines the
number of times the adjustment is applied over 976 of these periods. The resulting correction is as follows:
6
FREQCORR.VALUE
Correction in PPM = ----------------------------------------------------- ⋅ 10 PPM
1024 ⋅ 976
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This results in a resolution of 1.0006PPM.
The Sign bit in the Frequency Correction register (FREQCORR.SIGN) determines the direction of the correction. A
positive value will speed up the frequency, and a negative value will slow down the frequency.
Digital correction also affects the generation of the periodic events from the prescaler. When the correction is applied at
the end of the correction cycle period, the interval between the previous periodic event and the next occurrence may also
be shortened or lengthened depending on the correction value.
18.6.5 DMA Operation
Not applicable.
18.6.6 Interrupts
The RTC has the following interrupt sources:
z
Overflow (INTFLAG.OVF): this is an asynchronous interrupt and can be used to wake-up the device from any
sleep mode.
z
Compare n (INTFLAG.CMPn): this is an asynchronous interrupt and can be used to wake-up the device from any
sleep mode.
z
Alarm n (INTFLAG.ALARM0): this is an asynchronous interrupt and can be used to wake-up the device from any
sleep mode.
z
Synchronization Ready (INTFLAG.SYNCRDY): this is an asynchronous interrupt and can be used to wake-up the
device from any sleep mode.
Each interrupt source has an interrupt flag associated with it. The interrupt flag in the Interrupt Flag Status and Clear
register (INTFLAG) is set when the interrupt condition occurs. Each interrupt can be individually enabled by writing a one
to the corresponding bit in the Interrupt Enable Set register (INTENSET), and disabled by writing a one to the
corresponding bit in the Interrupt Enable Clear register (INTENCLR). An interrupt request is generated when the interrupt
flag is set and the corresponding interrupt is enabled. The interrupt request remains active until the interrupt flag is
cleared, the interrupt is disabled or the RTC is reset. See INTFLAG for details on how to clear interrupt flags. The RTC
has one common interrupt request line for all the interrupt sources. The user must read INTFLAG to determine which
interrupt condition is present.
Note that interrupts must be globally enabled for interrupt requests to be generated. Refer to “Nested Vector Interrupt
Controller” on page 30 for details.
18.6.7 Events
The RTC can generate the following output events, which are generated in the same way as the corresponding
interrupts:
z
Overflow (OVF)
z
Period n (PERn)
z
Compare n (CMPn)
z
Alarm n (ALARMn)
Output events must be enabled to be generated. Writing a one to an Event Output bit in the Event Control register
(EVCTRL.xxEO) enables the corresponding output event. Writing a zero to this bit disables the corresponding output
event. Refer to “EVSYS – Event System” on page 313 for details.
18.6.8 Sleep Mode Operation
The RTC will continue to operate in any sleep mode where the source clock is active. The RTC interrupts can be used to
wake up the device from a sleep mode, or the RTC events can trigger other operations in the system without exiting the
sleep mode.
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An interrupt request will be generated after the wake-up if the Interrupt Controller is configured accordingly. Otherwise
the CPU will wake up directly, without triggering an interrupt. In this case, the CPU will continue executing from the
instruction following the entry into sleep.
The periodic events can also wake up the CPU through the interrupt function of the Event System. In this case, the event
must be enabled and connected to an event channel with its interrupt enabled. See “EVSYS – Event System” on page
313 for more information.
18.6.9 Synchronization
Due to the asynchronicity between CLK_RTC_APB and GCLK_RTC some registers must be synchronized when
accessed. A register can require:
z
Synchronization when written
z
Synchronization when read
z
Synchronization when written and read
z
No synchronization
When executing an operation that requires synchronization, the Synchronization Busy bit in the Status
register(STATUS.SYNCBUSY) will be set immediately, and cleared when synchronization is complete. The
synchronization Ready interrupt can be used to signal when sync is complete. This can be accessed via the
Synchronization Ready Interrupt Flag in the Interrupt Flag Status and Clear register (INTFLAG.SYNCRDY).
If an operation that requires synchronization is executed while STATUS.SYNCBUSY is one, the bus will be stalled. All
operations will complete successfully, but the CPU will be stalled and interrupts will be pending as long as the bus is
stalled.
The following bits need synchronization when written:
z
Software Reset bit in the Control register (CTRL.SWRST)
z
Enable bit in the Control register (CTRL.ENABLE)
The following registers need synchronization when written:
z
The Counter Value register (COUNT)
z
The Clock Value register (CLOCK)
z
The Counter Period register (PER)
z
The Compare n Value registers (COMPn)
z
The Alarm n Value registers (ALARMn)
z
The Frequency Correction register (FREQCORR)
z
The Alarm n Mask register (MASKn)
Write-synchronization is denoted by the Write-Synchronization property in the register description.
The following registers need synchronization when read:
z
The Counter Value register (COUNT)
z
The Clock Value register (CLOCK)
Read-synchronization is denoted by the Read-Synchronization property in the register description.
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18.7
Register Summary
The register mapping depends on the Operating Mode bits in the Control register (CTRL.MODE). The register summary
is presented for each of the three modes.
Table 18-1. Register Summary - Mode 0 Registers
Offset
Name
0x00
Bit Pos.
7:0
MATCHCLR
CLKREP
MODE[1:0]
ENABLE
SWRST
CTRL
0x01
15:8
0x02
PRESCALER[3:0]
7:0
ADDR[5:0]
READREQ
0x03
0x04
15:8
RREQ
RCONT
7:0
PEREO7
PEREO6
15:8
OVFEO
PEREO5
PEREO4
PEREO3
PEREO2
PEREO1
PEREO0
EVCTRL
0x05
CMPEO0
0x06
INTENCLR
7:0
OVF
SYNCRDY
CMP0
0x07
INTENSET
7:0
OVF
SYNCRDY
CMP0
0x08
INTFLAG
7:0
OVF
SYNCRDY
CMP0
0x09
Reserved
0x0A
STATUS
7:0
SYNCBUSY
0x0B
DBGCTRL
7:0
0x0C
FREQCORR
7:0
0x0D
Reserved
0x0E
Reserved
0x0F
Reserved
0x10
DBGRUN
SIGN
VALUE[6:0]
7:0
COUNT[7:0]
15:8
COUNT[15:8]
0x12
23:16
COUNT[23:16]
0x13
31:24
COUNT[31:24]
7:0
COMP[7:0]
15:8
COMP[15:8]
0x1A
23:16
COMP[23:16]
0x1B
31:24
COMP[31:24]
0x11
COUNT
0x14
Reserved
0x15
Reserved
0x16
Reserved
0x17
Reserved
0x18
0x19
COMP0
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Table 18-2. Register Summary - Mode 1 Registers
Offset
Name
0x00
Bit Pos.
7:0
MATCHCLR
CLKREP
MODE[1:0]
ENABLE
SWRST
CTRL
0x01
PRESCALER[3:0]
15:8
7:0
0x02
ADDR[5:0]
READREQ
0x03
0x04
15:8
RREQ
RCONT
7:0
PEREO7
PEREO6
15:8
OVFEO
PEREO5
PEREO4
PEREO3
PEREO2
PEREO1
PEREO0
CMPEO1
CMPEO0
EVCTRL
0x05
0x06
INTENCLR
7:0
OVF
SYNCRDY
CMP1
CMP0
0x07
INTENSET
7:0
OVF
SYNCRDY
CMP1
CMP0
0x08
INTFLAG
7:0
OVF
SYNCRDY
CMP1
CMP0
0x09
Reserved
0x0A
STATUS
7:0
SYNCBUSY
0x0B
DBGCTRL
7:0
0x0C
FREQCORR
7:0
0x0D
Reserved
0x0E
Reserved
0x0F
Reserved
0x10
DBGRUN
SIGN
VALUE[6:0]
7:0
COUNT[7:0]
15:8
COUNT[15:8]
7:0
PER[7:0]
15:8
PER[15:8]
7:0
COMP[7:0]
15:8
COMP[15:8]
7:0
COMP[7:0]
15:8
COMP[15:8]
COUNT
0x11
0x12
Reserved
0x13
Reserved
0x14
PER
0x15
0x16
Reserved
0x17
Reserved
0x18
COMP0
0x19
0x1A
COMP1
0x1B
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Table 18-3. Register Summary - Mode 2 Registers
Offset
Name
0x00
Bit Pos.
7:0
MATCHCLR
CLKREP
MODE[1:0]
ENABLE
SWRST
CTRL
0x01
PRESCALER[3:0]
15:8
7:0
0x02
ADDR[5:0]
READREQ
0x03
0x04
15:8
RREQ
RCONT
7:0
PEREO7
PEREO6
15:8
OVFEO
PEREO5
PEREO4
PEREO3
PEREO2
PEREO1
PEREO0
EVCTRL
0x05
ALARMEO0
0x06
INTENCLR
7:0
OVF
SYNCRDY
ALARM0
0x07
INTENSET
7:0
OVF
SYNCRDY
ALARM0
0x08
INTFLAG
7:0
OVF
SYNCRDY
ALARM0
0x09
Reserved
0x0A
STATUS
7:0
SYNCBUSY
0x0B
DBGCTRL
7:0
0x0C
FREQCORR
7:0
0x0D
Reserved
0x0E
Reserved
0x0F
Reserved
0x10
7:0
0x11
DBGRUN
SIGN
VALUE[6:0]
MINUTE[1:0]
15:8
SECOND[5:0]
HOUR[3:0]
MINUTE[5:2]
CLOCK
0x12
23:16
0x13
31:24
0x14
Reserved
0x15
Reserved
0x16
Reserved
0x17
Reserved
7:0
0x18
0x19
MONTH[1:0]
DAY[4:0]
HOUR[4]
YEAR[5:0]
MINUTE[1:0]
15:8
MONTH[3:2]
SECOND[5:0]
HOUR[3:0]
MINUTE[5:2]
ALARM0
0x1A
23:16
0x1B
31:24
0x1C
MASK0
7:0
MONTH[1:0]
DAY[4:0]
YEAR[5:0]
HOUR[4]
MONTH[3:2]
SEL[2:0]
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18.8
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-Protected property in each individual register description. Refer to “Register Access Protection” on page 204
for details.
Some registers require synchronization when read and/or written. Synchronization is denoted by the Write-Synchronized
or the Read-Synchronized property in each individual register description. Refer to “Synchronization” on page 209 for
details.
Some registers are enable-protected, meaning they can only be written when the RTC is disabled. Enable-protection is
denoted by the Enable-Protected property in each individual register description.
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18.8.1 Control
18.8.1.1 Mode 0
Name:
CTRL
Offset:
0x00
Reset:
0x0000
Property:
Write-Protected, Enable-Protected, Write-Synchronized
Bit
15
14
13
12
11
10
9
8
PRESCALER[3:0]
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ENABLE
SWRST
MATCHCLR
Access
Reset
MODE[1:0]
R/W
R
R
R
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 15:12 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 11:8 – PRESCALER[3:0]: Prescaler
These bits define the prescaling factor for the RTC clock source (GCLK_RTC) to generate the counter clock
(CLK_RTC_CNT).
These bits are not synchronized.
Table 18-4. Prescaler
PRESCALER[3:0]
Prescaler
Description
0x0
DIV1
CLK_RTC_CNT = GCLK_RTC/1
0x1
DIV2
CLK_RTC_CNT = GCLK_RTC/2
0x2
DIV4
CLK_RTC_CNT = GCLK_RTC/4
0x3
DIV8
CLK_RTC_CNT = GCLK_RTC/8
0x4
DIV16
CLK_RTC_CNT = GCLK_RTC/16
0x5
DIV32
CLK_RTC_CNT = GCLK_RTC/32
0x6
DIV64
CLK_RTC_CNT = GCLK_RTC/64
0x7
DIV128
CLK_RTC_CNT = GCLK_RTC/128
0x8
DIV256
CLK_RTC_CNT = GCLK_RTC/256
0x9
DIV512
CLK_RTC_CNT = GCLK_RTC/512
0xA
DIV1024
CLK_RTC_CNT = GCLK_RTC/1024
0xB-0xF
-
Reserved
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z
Bit 7 – MATCHCLR: Clear on Match
This bit is valid only in Mode 0 and Mode 2. This bit can be written only when the peripheral is disabled.
0: The counter is not cleared on a Compare/Alarm 0 match.
1: The counter is cleared on a Compare/Alarm 0 match.
This bit is not synchronized.
z
Bits 6:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 3:2 – MODE[1:0]: Operating Mode
These bits define the operating mode of the RTC.
These bits are not synchronized.
Table 18-5. Peripheral Operating Mode
MODE[1:0]
Operating Mode
Description
0x0
COUNT32
Mode 0: 32-bit Counter
0x1
COUNT16
Mode 1: 16-bit Counter
0x2
CLOCK
Mode 2: Clock/Calendar
0x3
-
Reserved
z
Bit 1 – ENABLE: Enable
0: The peripheral is disabled or being disabled.
1: The peripheral is enabled or being enabled.
Due to synchronization, there is delay from writing CTRL.ENABLE until the peripheral is enabled/disabled. The
value written to CTRL.ENABLE will read back immediately, and the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set. STATUS.SYNCBUSY will be cleared when the operation is complete.
This bit is not enable-protected.
z
Bit 0 – SWRST: Software Reset
0: There is no reset operation ongoing.
1: The reset operation is ongoing.
Writing a zero to this bit has no effect.
Writing a one to this bit resets all registers in the RTC, except DBGCTRL, to their initial state, and the RTC will be
disabled.
Writing a one to CTRL.SWRST will always take precedence, meaning that all other writes in the same write-operation will be discarded.
Due to synchronization, there is a delay from writing CTRL.SWRST until the reset is complete. CTRL.SWRST and
STATUS.SYNCBUSY will both be cleared when the reset is complete.
This bit is not enable-protected.
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18.8.1.2 Mode 1
Name:
CTRL
Offset:
0x00
Reset:
0x0000
Property:
Write-Protected, Enable-Protected, Write-Synchronized
Bit
15
14
13
12
11
10
9
8
PRESCALER[3:0]
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ENABLE
SWRST
MODE[1:0]
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 15:12 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 11:8 – PRESCALER[3:0]: Prescaler
These bits define the prescaling factor for the RTC clock source (GCLK_RTC) to generate the counter clock
(CLK_RTC_CNT).
These bits are not synchronized.
Table 18-6. Prescaler
PRESCALER[3:0]
Prescaler
Description
0x0
DIV1
CLK_RTC_CNT = GCLK_RTC/1
0x1
DIV2
CLK_RTC_CNT = GCLK_RTC/2
0x2
DIV4
CLK_RTC_CNT = GCLK_RTC/4
0x3
DIV8
CLK_RTC_CNT = GCLK_RTC/8
0x4
DIV16
CLK_RTC_CNT = GCLK_RTC/16
0x5
DIV32
CLK_RTC_CNT = GCLK_RTC/32
0x6
DIV64
CLK_RTC_CNT = GCLK_RTC/64
0x7
DIV128
CLK_RTC_CNT = GCLK_RTC/128
0x8
DIV256
CLK_RTC_CNT = GCLK_RTC/256
0x9
DIV512
CLK_RTC_CNT = GCLK_RTC/512
0xA
DIV1024
CLK_RTC_CNT = GCLK_RTC/1024
0xB-0xF
-
Reserved
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z
Bits 7:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 3:2 – MODE[1:0]: Operating Mode
These bits define the operating mode of the RTC.
These bits are not synchronized.
Table 18-7. Peripheral Operating Mode
MODE[1:0]
Operating Mode
Description
0x0
COUNT32
Mode 0: 32-bit Counter
0x1
COUNT16
Mode 1: 16-bit Counter
0x2
CLOCK
Mode 2: Clock/Calendar
0x3
-
Reserved
z
Bit 1 – ENABLE: Enable
0: The peripheral is disabled or being disabled.
1: The peripheral is enabled or being enabled.
Due to synchronization, there is delay from writing CTRL.ENABLE until the peripheral is enabled/disabled. The
value written to CTRL.ENABLE will read back immediately, and the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set. STATUS.SYNCBUSY will be cleared when the operation is complete.
This bit is not enable-protected.
z
Bit 0 – SWRST: Software Reset
0: There is no reset operation ongoing.
1: The reset operation is ongoing.
Writing a zero to this bit has no effect.
Writing a one to this bit resets all registers in the RTC, except DBGCTRL, to their initial state, and the RTC will be
disabled.
Writing a one to CTRL.SWRST will always take precedence, meaning that all other writes in the same write-operation will be discarded.
Due to synchronization, there is a delay from writing CTRL.SWRST until the reset is complete. CTRL.SWRST and
STATUS.SYNCBUSY will both be cleared when the reset is complete.
This bit is not enable-protected.
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18.8.1.3 Mode 2
Name:
CTRL
Offset:
0x00
Reset:
0x0000
Property:
Write-Protected, Enable-Protected, Write-Synchronized
Bit
15
14
13
12
11
10
9
8
PRESCALER[3:0]
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
MATCHCLR
CLKREP
ENABLE
SWRST
R/W
R/W
R
R
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Access
Reset
MODE[1:0]
z
Bits 15:12 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 11:8 – PRESCALER[3:0]: Prescaler
These bits define the prescaling factor for the RTC clock source (GCLK_RTC) to generate the counter clock
(CLK_RTC_CNT).
These bits are not synchronized.
Table 18-8. Prescaler
PRESCALER[3:0]
Prescaler
Description
0x0
DIV1
CLK_RTC_CNT = GCLK_RTC/1
0x1
DIV2
CLK_RTC_CNT = GCLK_RTC/2
0x2
DIV4
CLK_RTC_CNT = GCLK_RTC/4
0x3
DIV8
CLK_RTC_CNT = GCLK_RTC/8
0x4
DIV16
CLK_RTC_CNT = GCLK_RTC/16
0x5
DIV32
CLK_RTC_CNT = GCLK_RTC/32
0x6
DIV64
CLK_RTC_CNT = GCLK_RTC/64
0x7
DIV128
CLK_RTC_CNT = GCLK_RTC/128
0x8
DIV256
CLK_RTC_CNT = GCLK_RTC/256
0x9
DIV512
CLK_RTC_CNT = GCLK_RTC/512
0xA
DIV1024
CLK_RTC_CNT = GCLK_RTC/1024
0xB-0xF
-
Reserved
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z
Bit 7 – MATCHCLR: Clear on Match
This bit is valid only in Mode 0 and Mode 2. This bit can be written only when the peripheral is disabled.
0: The counter is not cleared on a Compare/Alarm 0 match.
1: The counter is cleared on a Compare/Alarm 0 match.
This bit is not synchronized.
z
Bit 6 – CLKREP: Clock Representation
This bit is valid only in Mode 2 and determines how the hours are represented in the Clock Value (CLOCK) register. This bit can be written only when the peripheral is disabled.
0: 24 Hour
1: 12 Hour (AM/PM)
This bit is not synchronized.
z
Bits 5:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 3:2 – MODE[1:0]: Operating Mode
These bits define the operating mode of the RTC.
These bits are not synchronized.
Table 18-9. Peripheral Operating Mode
MODE[1:0]
Operating Mode
Description
0x0
COUNT32
Mode 0: 32-bit Counter
0x1
COUNT16
Mode 1: 16-bit Counter
0x2
CLOCK
Mode 2: Clock/Calendar
0x3
-
Reserved
z
Bit 1 – ENABLE: Enable
0: The peripheral is disabled or being disabled.
1: The peripheral is enabled or being enabled.
Due to synchronization, there is delay from writing CTRL.ENABLE until the peripheral is enabled/disabled. The
value written to CTRL.ENABLE will read back immediately, and the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set. STATUS.SYNCBUSY will be cleared when the operation is complete.
This bit is not enable-protected.
z
Bit 0 – SWRST: Software Reset
0: There is no reset operation ongoing.
1: The reset operation is ongoing.
Writing a zero to this bit has no effect.
Writing a one to this bit resets all registers in the RTC, except DBGCTRL, to their initial state, and the RTC will be
disabled.
Writing a one to CTRL.SWRST will always take precedence, meaning that all other writes in the same write-operation will be discarded.
Due to synchronization, there is a delay from writing CTRL.SWRST until the reset is complete. CTRL.SWRST and
STATUS.SYNCBUSY will both be cleared when the reset is complete.
This bit is not enable-protected.
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18.8.2 Read Request
Name:
READREQ
Offset:
0x02
Reset:
0x0010
Property:
–
Bit
15
14
13
12
11
10
9
8
RREQ
RCONT
Access
W
R/W
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ADDR[5:0]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bit 15 – RREQ: Read Request
Writing a zero to this bit has no effect.
Writing a one to this bit requests synchronization of the register pointed to by the Address bit group (READREQ.ADDR) and sets the Synchronization Busy bit in the Status register (STATUS.SYNCBUSY).
z
Bit 14 – RCONT: Read Continuously
Writing a zero to this bit disables continuous synchronization.
Writing a one to this bit enables continuous synchronization of the register pointed to by READREQ.ADDR. The
register value will be synchronized automatically every time the register is updated.
This bit is cleared when the register pointed to by READREQ.ADDR is written.
z
Bits 13:6 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 5:0 – ADDR: Address
These bits select the offset of the register that needs read synchronization. In the RTC only the COUNT and
CLOCK registers, which share the same address, are available for read synchronization. Therefore, the ADDR bit
group is a read-only constant of 0x10.
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18.8.3 Event Control
18.8.3.1 Mode 0
Name:
EVCTRL
Offset:
0x04
Reset:
0x0000
Property:
Write-Protected, Enable-Protected
Bit
15
14
13
12
11
10
9
OVFEO
Access
8
CMPEO0
R/W
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
PEREO7
PEREO6
PEREO5
PEREO4
PEREO3
PEREO2
PEREO1
PEREO0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Access
Reset
z
Bit 15 – OVFEO: Overflow Event Output Enable
0: Overflow event is disabled and will not be generated.
1: Overflow event is enabled and will be generated for every overflow.
z
Bits 14:9 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 8 – CMPEO0: Compare 0 Event Output Enable
0: Compare 0 event is disabled and will not be generated.
1: Compare 0 event is enabled and will be generated for every compare match.
z
Bits 7:0 – PEREOx: Periodic Interval x Event Output Enable
0: Periodic Interval m event is disabled and will not be generated.
1: Periodic Interval m event is enabled and will be generated.
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18.8.3.2 Mode 1
Name:
EVCTRL
Offset:
0x04
Reset:
0x0000
Property:
Write-Protected, Enable-Protected
Bit
15
14
13
12
11
10
OVFEO
Access
9
8
CMPEO1
CMPEO0
R/W
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
PEREO7
PEREO6
PEREO5
PEREO4
PEREO3
PEREO2
PEREO1
PEREO0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Access
Reset
z
Bit 15 – OVFEO: Overflow Event Output Enable
0: Overflow event is disabled and will not be generated.
1: Overflow event is enabled and will be generated for every overflow.
z
Bits 14:10 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 9 – CMPEO1: Compare Event Output Enable 1
0: Compare 1 event is disabled and will not be generated.
1: Compare 1 event is enabled and will be generated for every compare match.
z
Bit 8 – CMPEO0: Compare Event Output Enable 0
0: Compare 0 event is disabled and will not be generated.
1: Compare 0 event is enabled and will be generated for every compare match.
z
Bits 7:0 – PEREOx: Periodic Interval x Event Output Enable
0: Periodic Interval m event is disabled and will not be generated.
1: Periodic Interval m event is enabled and will be generated.
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18.8.3.3 Mode 2
Name:
EVCTRL
Offset:
0x04
Reset:
0x0000
Property:
Write-Protected, Enabled-Protected
Bit
15
14
13
12
11
10
9
OVFEO
Access
8
ALARMEO0
R/W
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
PEREO7
PEREO6
PEREO5
PEREO4
PEREO3
PEREO2
PEREO1
PEREO0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Access
Reset
z
Bit 15 – OVFEO: Overflow Event Output Enable
0: Overflow event is disabled and will not be generated.
1: Overflow event is enabled and will be generated for every overflow.
z
Bits 14:9 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 8 – ALARMEO0: Alarm 0 Event Output Enable
0: Alarm 0 event is disabled and will not be generated.
1: Alarm 0 event is enabled and will be generated for every alarm.
z
Bits 7:0 – PEREOx: Periodic Interval x Event Output Enable
0: Periodic Interval n event is disabled and will not be generated.
1: Periodic Interval n event is enabled and will be generated.
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18.8.4 Interrupt Enable Clear
This register allows the user to disable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Set register (INTENSET).
18.8.4.1 Mode 0
Name:
INTENCLR
Offset:
0x06
Reset:
0x00
Property:
Write-Protected
Bit
Access
Reset
z
7
6
5
4
3
2
1
0
OVF
SYNCRDY
R/W
R/W
R
R
R
R
R
R/W
0
0
0
0
0
0
0
0
CMP0
Bit 7 – OVF: Overflow Interrupt Enable
0: The Overflow interrupt is disabled.
1: The Overflow interrupt is enabled, and an interrupt request will be generated when the Overflow interrupt flag is
set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Overflow Interrupt Enable bit and disable the corresponding interrupt.
z
Bit 6 – SYNCRDY: Synchronization Ready Interrupt Enable
0: The Synchronization Ready interrupt is disabled.
1: The Synchronization Ready interrupt is enabled, and an interrupt request will be generated when the Synchronization Ready interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Synchronization Ready Interrupt Enable bit and disable the corresponding
interrupt.
z
Bits 5:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – CMP0: Compare 0 Interrupt Enable
0: The Compare 0 interrupt is disabled.
1: The Compare 0 interrupt is enabled, and an interrupt request will be generated when the Compare 0 interrupt
flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Compare 0 Interrupt Enable bit and disable the corresponding interrupt.
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18.8.4.2 Mode 1
Name:
INTENCLR
Offset:
0x06
Reset:
0x00
Property:
Write-Protected
Bit
Access
Reset
z
7
6
5
4
3
OVF
SYNCRDY
R/W
R/W
R
R
R
0
0
0
0
0
2
1
0
CMP1
CMP0
R
R/W
R/W
0
0
0
Bit 7 – OVF: Overflow Interrupt Enable
0: The Overflow interrupt is disabled.
1: The Overflow interrupt is enabled, and an interrupt request will be generated when the Overflow interrupt flag is
set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Overflow Interrupt Enable bit and disable the corresponding interrupt.
z
Bit 6 – SYNCRDY: Synchronization Ready Interrupt Enable
0: The Synchronization Ready interrupt is disabled.
1: The Synchronization Ready interrupt is enabled, and an interrupt request will be generated when the Synchronization Ready interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Synchronization Ready Interrupt Enable bit and disable the corresponding
interrupt.
z
Bits 5:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – CMP1: Compare 1 Interrupt Enable
0: The Compare 1 interrupt is disabled.
1: The Compare 1 interrupt is enabled, and an interrupt request will be generated when the Compare 1 interrupt
flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Compare 1 Interrupt Enable bit and disable the corresponding interrupt.
z
Bit 0 – CMP0: Compare 0 Interrupt Enable
0: The Compare 0 interrupt is disabled.
1: The Compare 0 interrupt is enabled, and an interrupt request will be generated when the Compare 0 interrupt
flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Compare 0 Interrupt Enable bit and disable the corresponding interrupt.
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18.8.4.3 Mode 2
Name:
INTENCLR
Offset:
0x06
Reset:
0x00
Property:
Write-protected
Bit
Access
Reset
z
7
6
5
4
3
2
1
0
OVF
SYNCRDY
R/W
R/W
R
R
R
R
R
R/W
0
0
0
0
0
0
0
0
ALARM0
Bit 7 – OVF: Overflow Interrupt Enable
0: The Overflow interrupt is disabled.
1: The Overflow interrupt is enabled, and an interrupt request will be generated when the Overflow interrupt flag is
set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Overflow Interrupt Enable bit and disable the corresponding interrupt.
z
Bit 6 – SYNCRDY: Synchronization Ready Interrupt Enable
0: The synchronization ready interrupt is disabled.
1: The synchronization ready interrupt is enabled, and an interrupt request will be generated when the Synchronization Ready interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Synchronization Ready Interrupt Enable bit and disable the corresponding
interrupt.
z
Bits 5:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – ALARM0: Alarm 0 Interrupt Enable
0: The Alarm 0 interrupt is disabled.
1: The Alarm 0 interrupt is enabled, and an interrupt request will be generated when the Alarm 0 interrupt flag is
set.
Writing a zero to this bit has no effect.
Writing a one to this bit disables the Alarm 0 interrupt.
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18.8.5 Interrupt Enable Set
This register allows the user to enable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Clear (INTENCLR) register.
18.8.5.1 Mode 0
Name:
INTENSET
Offset:
0x07
Reset:
0x00
Property:
Write-Protected
Bit
Access
Reset
z
7
6
5
4
3
2
1
0
OVF
SYNCRDY
R/W
R/W
R
R
R
R
R
R
0
0
0
0
0
0
0
0
CMP0
Bit 7 – OVF: Overflow Interrupt Enable
0: The overflow interrupt is disabled.
1: The overflow interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Overflow Interrupt Enable bit and enable the Overflow interrupt.
z
Bit 6 – SYNCRDY: Synchronization Ready Interrupt Enable
0: The synchronization ready interrupt is disabled.
1: The synchronization ready interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Synchronization Ready Interrupt Enable bit and enable the Synchronization
Ready interrupt.
z
Bits 5:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – CMP0: Compare 0 Interrupt Enable
0: The compare 0 interrupt is disabled.
1: The compare 0 interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Compare 0 Interrupt Enable bit and enable the Compare 0 interrupt.
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18.8.5.2 Mode 1
Name:
INTENSET
Offset:
0x07
Reset:
0x00
Property:
Write-Protected
Bit
Access
Reset
z
7
6
5
4
3
OVF
SYNCRDY
R/W
R/W
R
R
R
0
0
0
0
0
2
1
0
CMP1
CMP0
R
R/W
R/W
0
0
0
Bit 7 – OVF: Overflow Interrupt Enable
0: The overflow interrupt is disabled.
1: The overflow interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Overflow interrupt bit and enable the Overflow interrupt.
z
Bit 6 – SYNCRDY: Synchronization Ready Interrupt Enable
0: The synchronization ready interrupt is disabled.
1: The synchronization ready interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Synchronization Ready Interrupt Enable bit and enable the Synchronization
Ready interrupt.
z
Bits 5:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – CMP1: Compare 1 Interrupt Enable
0: The compare 1 interrupt is disabled.
1: The compare 1 interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Compare 1 Interrupt Enable bit and enable the Compare 1 interrupt.
z
Bit 0 – CMP0: Compare 0 Interrupt Enable
0: The compare 0 interrupt is disabled.
1: The compare 0 interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Compare 0 Interrupt Enable bit and enable the Compare 0 interrupt.
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18.8.5.3 Mode 2
Name:
INTENSET
Offset:
0x07
Reset:
0x00
Property:
Write-Protected
Bit
Access
Reset
z
7
6
5
4
3
2
1
0
OVF
SYNCRDY
R/W
R/W
R
R
R
R
R
R/W
0
0
0
0
0
0
0
0
ALARM0
Bit 7 – OVF: Overflow Interrupt Enable
0: The overflow interrupt is disabled.
1: The overflow interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Overflow Interrupt Enable bit and enable the Overflow interrupt.
z
Bit 6 – SYNCRDY: Synchronization Ready Interrupt Enable
0: The synchronization ready interrupt is disabled.
1: The synchronization ready interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Synchronization Ready Interrupt bit and enable the Synchronization Ready
interrupt.
Reading this bit returns the state of the synchronization ready interrupt enable.
z
Bits 5:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – ALARM0: Alarm0 Interrupt Enable
0: The alarm 0 interrupt is disabled.
1: The alarm 0 interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Alarm 0 Interrupt Enable bit and enable the Alarm 0 interrupt.
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18.8.6 Interrupt Flag Status and Clear
18.8.6.1 Mode 0
Name:
INTFLAG
Offset:
0x08
Reset:
0x00
Property:
-
Bit
Access
Reset
z
7
6
5
4
3
2
1
0
OVF
SYNCRDY
R/W
R/W
R
R
R
R
R
R/W
0
0
0
0
0
0
0
0
CMP0
Bit 7 – OVF: Overflow
This flag is cleared by writing a one to the flag.
This flag is set on the next CLK_RTC_CNT cycle after an overflow condition occurs, and an interrupt request will
be generated ifINTENCLR/SET.OVF is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Overflow interrupt flag.
z
Bit 6 – SYNCRDY: Synchronization Ready
This flag is cleared by writing a one to the flag.
This flag is set on a 1-to-0 transition of the Synchronization Busy bit in the Status register (STATUS.SYNCBUSY),
except when caused by Enable or software Reset, and an interrupt request will be generated if INTENCLR/SET.SYNCRDY is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Synchronization Ready interrupt flag.
z
Bits 5:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – CMP0: Compare 0
This flag is cleared by writing a one to the flag.
This flag is set on the next CLK_RTC_CNT cycle after a match with the compare condition, and an interrupt
request will be generated if INTENCLR/SET.COMP0 is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Compare 0 interrupt flag.
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18.8.6.2 Mode 1
Name:
INTFLAG
Offset:
0x08
Reset:
0x00
Property:
-
Bit
Access
Reset
z
7
6
5
4
3
OVF
SYNCRDY
R/W
R/W
R
R
R
0
0
0
0
0
2
1
0
CMP1
CMP0
R
R/W
R/W
0
0
0
Bit 7 – OVF: Overflow
This flag is cleared by writing a one to the flag.
This flag is set on the next CLK_RTC_CNT cycle after an overflow condition occurs, and an interrupt request will
be generated ifINTENCLR/SET.OVF is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Overflow interrupt flag.
z
Bit 6 – SYNCRDY: Synchronization Ready
This flag is cleared by writing a one to the flag.
This flag is set on a 1-to-0 transition of the Synchronization Busy bit in the Status register (STATUS.SYNCBUSY),
except when caused by Enable or software Reset, and an interrupt request will be generated if INTENCLR/SET.SYNCRDY is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Synchronization Ready interrupt flag.
z
, and an interrupt request will be generatedBits 5:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – CMP1: Compare 1
This flag is cleared by writing a one to the flag.
This flag is set on the next CLK_RTC_CNT cycle after a match with the compare condition, and an interrupt
request will be generated if INTENCLR/SET.COMP1 is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Compare 1 interrupt flag.
z
Bit 0 – CMP0: Compare 0
This flag is cleared by writing a one to the flag.
This flag is set on the next CLK_RTC_CNT cycle after a match with the compare condition, and an interrupt
request will be generated if INTENCLR/SET.COMP0 is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Compare 0 interrupt flag.
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18.8.6.3 Mode 2
Name:
INTFLAG
Offset:
0x08
Reset:
0x00
Property:
–
Bit
Access
Reset
z
7
6
5
4
3
2
1
0
OVF
SYNCRDY
R/W
R/W
R
R
R
R
R
R/W
0
0
0
0
0
0
0
0
ALARM0
Bit 7 – OVF: Overflow
This flag is cleared by writing a one to the flag.
This flag is set on the next CLK_RTC_CNT cycle after an overflow condition occurs, and an interrupt request will
be generated if INTENCLR/SET.OVF is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Overflow interrupt flag.
z
Bit 6 – SYNCRDY: Synchronization Ready
This flag is cleared by writing a one to the flag.
This flag is set on a 1-to-0 transition of the Synchronization Busy bit in the Status register (STATUS.SYNCBUSY),
except when caused by Enable or software Reset, and an interrupt request will be generated if INTENCLR/SET.SYNCRDY is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Synchronization Ready interrupt flag.
z
Bits 5:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – ALARM0: Alarm 0
This flag is cleared by writing a one to the flag.
This flag is set on the next CLK_RTC_CNT cycle after a match with ALARM0 condition occurs, and an interrupt
request will be generated if INTENCLR/SET.ALARM0 is also one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Alarm 0 interrupt flag.
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18.8.7 Status
Name:
STATUS
Offset:
0x0A
Reset:
0x00
Property:
–
Bit
7
6
5
4
3
2
1
0
SYNCBUSY
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bit 7 – SYNCBUSY: Synchronization Busy
This bit is cleared when the synchronization of registers between the clock domains is complete.
This bit is set when the synchronization of registers between clock domains is started.
z
Bits 6:0 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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18.8.8 Debug Control
Name:
DBGCTRL
Offset:
0x0B
Reset:
0x00
Property:
–
Bit
7
6
5
4
3
2
1
0
DBGRUN
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – DBGRUN: Run During Debug
This bit is not reset by a software reset.
Writing a zero to this bit causes the RTC to halt during debug mode.
Writing a one to this bit allows the RTC to continue normal operation during debug mode.
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18.8.9 Frequency Correction
Name:
FREQCORR
Offset:
0x0C
Reset:
0x00
Property:
Write-Protected, Write-Synchronized
Bit
7
6
5
4
SIGN
Access
Reset
3
2
1
0
VALUE[6:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bit 7 – SIGN: Correction Sign
0: The correction value is positive, i.e., frequency will be increased.
1: The correction value is negative, i.e., frequency will be decreased.
z
Bits 6:0 – VALUE[6:0]: Correction Value
These bits define the amount of correction applied to the RTC prescaler.
0: Correction is disabled and the RTC frequency is unchanged.
1–127: The RTC frequency is adjusted according to the value.
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18.8.10 Counter Value
18.8.10.1 Mode 0
Name:
COUNT
Offset:
0x10
Reset:
0x00000000
Property:
Write-Protected, Write-Synchronized, Read-Synchronized
Bit
31
30
29
28
27
26
25
24
COUNT[31:24]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
COUNT[23:16]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
COUNT[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
COUNT[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31:0 – COUNT[31:0]: Counter Value
These bits define the value of the 32-bit RTC counter.
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18.8.10.2 Mode 1
Name:
COUNT
Offset:
0x10
Reset:
0x0000
Property:
Write-Protected, Write-Synchronized, Read-Synchronized
Bit
15
14
13
12
11
10
9
8
COUNT[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
COUNT[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 15:0 – COUNT[15:0]: Counter Value
These bits define the value of the 16-bit RTC counter.
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18.8.11 Clock Value
18.8.11.1 Mode 2
Name:
CLOCK
Offset:
0x10
Reset:
0x00000000
Property:
Write-Protected, Write-Synchronized, Read-Synchronized
Bit
31
30
29
28
27
26
25
YEAR[5:0]
Access
24
MONTH[3:2]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
MONTH[1:0]
Access
DAY[4:0]
HOUR[4]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
HOUR[3:0]
Access
MINUTE[5:2]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
MINUTE[1:0]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Reset
z
SECOND[5:0]
Bits 31:26 – YEAR[5:0]: Year
The year offset with respect to the reference year (defined in software).
The year is considered a leap year if YEAR[1:0] is zero.
z
Bits 25:22 – MONTH[3:0]: Month
1 – January
2 – February
…
12 – December
z
Bits 21:17 – DAY[4:0]: Day
Day starts at 1 and ends at 28, 29, 30 or 31, depending on the month and year.
z
Bits 16:12 – HOUR[4:0]: Hour
When CTRL.CLKREP is zero, the Hour bit group is in 24-hour format, with values 0-23. When CTRL.CLKREP is
one, HOUR[3:0] has values 1-12 and HOUR[4] represents AM (0) or PM (1).
z
Bits 11:6 – MINUTE[5:0]: Minute
0 – 59.
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z
Bits 5:0 – SECOND[5:0]: Second
0– 59.
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18.8.12 Counter Period
18.8.12.1 Mode 1
Name:
PER
Offset:
0x14
Reset:
0x0000
Property:
Write-Protected, Write-Synchronized
Bit
15
14
13
12
11
10
9
8
PER[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
PER[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 15:0 – PER[15:0]: Counter Period
These bits define the value of the 16-bit RTC period.
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18.8.13 Compare n Value
18.8.13.1 Mode 0
Name:
COMPn
Offset:
0x18 + n*0x4 [n=0..3]
Reset:
0x00000000
Property:
Write-Protected, Write-Synchronized
Bit
31
30
29
28
27
26
25
24
COMP[31:24]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
COMP[23:16]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
COMP[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
COMP[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31:0 – COMP[31:0]: Compare Value
The 32-bit value of COMPn is continuously compared with the 32-bit COUNT value. When a match occurs, the
Compare n interrupt flag in the Interrupt Flag Status and Clear register (INTFLAG.CMPn) is set on the next counter
cycle, and the counter value is cleared if CTRL.MATCHCLR is one.
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18.8.13.2 Mode 1
Name:
COMPn
Offset:
0x18 + n*0x2 [n=0..5]
Reset:
0x0000
Property:
Write-Protected, Write-Synchronized
Bit
15
14
13
12
11
10
9
8
COMP[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
COMP[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 15:0 – COMP[15:0]: Compare Value
The 16-bit value of COMPn is continuously compared with the 16-bit COUNT value. When a match occurs, the
Compare n interrupt flag in the Interrupt Flag Status and Clear register (INTFLAG.CMPn) is set on the next counter
cycle.
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18.8.14 Alarm n Value
18.8.14.1 Mode 2
Name:
ALARMn
Offset:
0x18 + n*0x8 [n=0..3]
Reset:
0x00000000
Property:
Write-Protected, Write-Synchronized
Bit
31
30
29
28
27
26
25
YEAR[5:0]
Access
24
MONTH[3:2]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
MONTH[1:0]
Access
DAY[4:0]
HOUR[4]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
HOUR[3:0]
Access
MINUTE[5:2]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
MINUTE[1:0]
Access
Reset
SECOND[5:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
The 32-bit value of ALARMn is continuously compared with the 32-bit CLOCK value, based on the masking set by
MASKn.SEL. When a match occurs, the Alarm n interrupt flag in the Interrupt Flag Status and Clear register
(INTFLAG.ALARMn) is set on the next counter cycle, and the counter is cleared if CTRL.MATCHCLR is one.
z
Bits 31:26 – YEAR[5:0]: Year
The alarm year. Years are only matched if MASKn.SEL is 6.
z
Bits 25:22 – MONTH[3:0]: Month
The alarm month. Months are matched only if MASKn.SEL is greater than 4.
z
Bits 21:17 – DAY[4:0]: Day
The alarm day. Days are matched only if MASKn.SEL is greater than 3.
z
Bits 16:12 – HOUR[4:0]: Hour
The alarm hour. Hours are matched only if MASKn.SEL is greater than 2.
z
Bits 11:6 – MINUTE[5:0]: Minute
The alarm minute. Minutes are matched only if MASKn.SEL is greater than 1.
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z
Bits 5:0 – SECOND[5:0]: Second
The alarm second. Seconds are matched only if MASKn.SEL is greater than 0.
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18.8.15 Alarm n Mask
18.8.15.1 Mode 2
Name:
MASKn
Offset:
0x1C + n*0x8 [n=0..3]
Reset:
0x00
Property:
Write-Protected, Write-Synchronized
Bit
7
6
5
4
3
2
1
0
SEL[2:0]
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 2:0 – SEL[2:0]: Alarm Mask Selection
These bits define which bit groups of Alarm n are valid.
Table 18-10. Alarm Mask Selection
SEL[2:0]
Alarm Mask Selection
Description
0x0
OFF
Alarm Disabled
0x1
SS
Match seconds only
0x2
MMSS
Match seconds and minutes only
0x3
HHMMSS
Match seconds, minutes and hours only
0x4
DDHHMMSS
Match seconds, minutes, hours and days only
0x5
MMDDHHMMSS
Match seconds, minutes, hours, days and months only
0x6
YYMMDDHHMMSS
Match seconds, minutes, hours, days, months and years
0x7
-
Reserved
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19.
EIC – External Interrupt Controller
19.1
Overview
The External Interrupt Controller (EIC) allows external pins to be configured as interrupt lines. Each interrupt line can be
individually masked and can generate an interrupt on rising, falling or both edges, or on high or low levels. Each external
pin has a configurable filter to remove spikes. Each external pin can also be configured to be asynchronous in order to
wake up the device from sleep modes where all clocks have been disabled. External pins can also generate an event.
A separate non-maskable interrupt (NMI) is also supported. It has properties similar to the other external interrupts, but is
connected to the NMI request of the CPU, enabling it to interrupt any other interrupt mode.
19.2
19.3
Features
z
16 external pins, plus one non-maskable pin
z
Dedicated interrupt line for each pin
z
Individually maskable interrupt lines
z
Interrupt on rising, falling or both edges
z
Interrupt on high or low levels
z
Asynchronous interrupts for sleep modes without clock
z
Filtering of external pins
z
Event generation
z
Configurable wake-up for sleep modes
Block Diagram
Figure 19-1. EIC Block Diagram
FILTENx
SENSEx[2:0]
intreq_extint[x]
Interrupt
EXTINTx
Filter
Edge/Level
Detection
inwake_extint[x]
Wake
evt_extint[x]
Event
NMIFILTEN
NMISENSE[2:0]
intreq_nmi
Interrupt
NMI
Filter
Edge/Level
Detection
inwake_nmi
Wake
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19.4
Signal Description
Signal Name
Type
Description
EXTINT[15..0]
Digital Input
External interrupt pin
NMI
Digital Input
Non-maskable interrupt pin
Refer to “I/O Multiplexing and Considerations” on page 16 for details on the pin mapping for this peripheral. One signal
can be mapped on several pins.
19.5
Product Dependencies
In order to use this EIC, other parts of the system must be configured correctly, as described below.
19.5.1 I/O Lines
Using the EIC’s I/O lines requires the I/O pins to be configured. Refer to “PORT” on page 287 for details.
19.5.2 Power Management
All interrupts are available in all sleep modes, but the EIC can be configured to automatically mask some interrupts in
order to prevent device wake-up.
The EIC will continue to operate in any sleep mode where the selected source clock is running. The EIC’s interrupts can
be used to wake up the device from sleep modes. Events connected to the Event System can trigger other operations in
the system without exiting sleep modes. Refer to “PM – Power Manager” on page 107 for details on the different sleep
modes.
19.5.3 Clocks
The EIC bus clock (CLK_EIC_APB) can be enabled and disabled in the Power Manager, and the default state of
CLK_EIC_APB can be found in the Peripheral Clock Masking section in “PM – Power Manager” on page 107.
A generic clock (GCLK_EIC) is required to clock the peripheral. This clock must be configured and enabled in the
Generic Clock Controller before using the peripheral. Refer to “GCLK – Generic Clock Controller” on page 85 for details.
This generic clock is asynchronous to the user interface clock (CLK_EIC_APB). Due to this asynchronicity, writes to
certain registers will require synchronization between the clock domains. Refer to “Synchronization” on page 251 for
further details.
19.5.4 Interrupts
There are two interrupt request lines, one for the external interrupts (EXTINT) and one for non-maskable interrupt (NMI).
The EXTINT interrupt request line is connected to the interrupt controller. Using the EIC interrupt requires the interrupt
controller to be configured first. Refer to “Nested Vector Interrupt Controller” on page 30 for details.
The NMI interrupt request line is also connected to the interrupt controller, but does not require the interrupt to be
configured.
19.5.5 Events
The events are connected to the Event System. Using the events requires the Event System to be configured first. The
External Interrupt Controller generates events as pulses.
Refer to “EVSYS – Event System” on page 313 for details.
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19.5.6 Debug Operation
When the CPU is halted in debug mode, the EIC continues normal operation. If the EIC is configured in a way that
requires it to be periodically serviced by the CPU through interrupts or similar, improper operation or data loss may result
during debugging.
19.5.7 Register Access Protection
All registers with write-access are optionally write-protected by the Peripheral Access Controller (PAC), except the
following registers:
z
Interrupt Flag Status and Clear register (INTFLAG - refer to INTFLAG)
z
Non-Maskable Interrupt Flag Status and Clear register (NMIFLAG - refer to NMIFLAG)
Write-protection is denoted by the Write-Protected property in the register description.
Write-protection does not apply to accesses through an external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
19.5.8 Analog Connections
Not applicable.
19.6
Functional Description
19.6.1 Principle of Operation
The EIC detects edge or level condition to generate interrupts to the CPU Interrupt Controller or events to the Event
System. Each external interrupt pin (EXTINT) can be filtered using majority vote filtering, clocked by generic clock
GCLK_EIC.
19.6.2 Basic Operation
19.6.2.1 Initialization
The EIC must be initialized in the following order:
1.
Enable CLK_EIC_APB
2.
If edge detection or filtering is required, GCLK_EIC must be enabled
3.
Write the EIC configuration registers (EVCTRL, WAKEUP, CONFIGy)
4.
Enable the EIC
When NMI is used, GCLK_EIC must be enabled after EIC configuration (NMICTRL).
19.6.2.2 Enabling, Disabling and Resetting
The EIC is enabled by writing a one to the Enable bit in the Control register (CTRL.ENABLE). The EIC is disabled by
writing a zero to CTRL.ENABLE.
The EIC is reset by writing a one to the Software Reset bit in the Control register (CTRL.SWRST). All registers in the EIC
will be reset to their initial state, and the EIC will be disabled.
Refer to CTRL register for details.
19.6.3 External Pin Processing
Each external pin can be configured to generate an interrupt/event on edge detection (rising, falling or both edges) or
level detection (high or low). The sense of external pins is configured by writing the Interrupt Sense x bits in the Config y
register (CONFIGy.SENSEx). The corresponding interrupt flag (INTFLAG.EXTINT[x]) in the Interrupt Flag Status and
Clear register (INTFLAG) is set when the interrupt condition is met (CONFIGy.SENSEx must be different from zero).
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When the interrupt has been cleared in edge-sensitive mode, INTFLAG.EXTINT[x] will only be set if a new interrupt
condition is met. In level-sensitive mode, when interrupt has been cleared, INTFLAG.EXTINT[x] will be set immediately if
the EXTINTx pin still matches the interrupt condition.
Each external pin can be filtered by a majority vote filtering, clocked by GCLK_EIC. Filtering is enabled if bit Filter Enable
x in the Configuration y register (CONFIGy.FILTENx) is written to one. The majority vote filter samples the external pin
three times with GCLK_EIC and outputs the value when two or more samples are equal.
Table 19-1. Majority Vote Filter
Samples [0, 1, 2]
Filter Output
[0,0,0]
0
[0,0,1]
0
[0,1,0]
0
[0,1,1]
1
[1,0,0]
0
[1,0,1]
1
[1,1,0]
1
[1,1,1]
1
When an external interrupt is configured for level detection, or if filtering is disabled, detection is made asynchronously,
and GCLK_EIC is not required.
If filtering or edge detection is enabled, the EIC automatically requests the GCLK_EIC to operate (GCLK_EIC must be
enabled in the GCLK module, see “GCLK – Generic Clock Controller” on page 85 for details). If level detection is
enabled, GCLK_EIC is not required, but interrupt and events can still be generated.
Figure 19-2. Interrupt detections
GCLK_EIC
CLK_EIC_APB
EXTINTx
intreq_extint[x]
(level detection / no filter)
intreq_extint[x]
(level detection / filter)
No interrupt
intreq_extint[x]
(edge detection / no filter)
intreq_extint[x]
(edge detection / filter)
No interrupt
clear INTFLAG.EXTINT[x]
The detection delay depends on the detection mode.
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Table 19-2. Interrupt Latency
Detection Mode
Latency (Worst Case)
Level without filter
3 CLK_EIC_APB periods
Level with filter
4 GCLK_EIC periods + 3 CLK_EIC_APB periods
Edge without filter
4 GCLK_EIC periods + 3 CLK_EIC_APB periods
Edge with filter
6 GCLK_EIC periods + 3 CLK_EIC_APB periods
19.6.4 Additional Features
The non-maskable interrupt pin can also generate an interrupt on edge or level detection, but it is configured with the
dedicated NMI Control register (NMICTRL - refer to NMICTRL). To select the sense for NMI, write to the NMISENSE bit
group in the NMI Control register (NMICTRL.NMISENSE). NMI filtering is enabled by writing a one to the NMI Filter
Enable bit (NMICTRL.NMIFILTEN).
NMI detection is enabled only by the NMICTRL.NMISENSE value, and the EIC is not required to be enabled.
After reset, NMI is configured to no detection mode.
When an NMI is detected, the non-maskable interrupt flag in the NMI Flag Status and Clear register is set
(NMIFLAG.NMI). NMI interrupt generation is always enabled, and NMIFLAG.NMI generates an interrupt request when
set.
19.6.5 Interrupts
The EIC has the following interrupt sources:
z
External interrupt pins (EXTINTx). This is an asynchronous interrupt if the corresponding WAKEUP register bit is
set, and can be used to wake-up the device from any sleep mode. See “Basic Operation” on page 248
z
Non-maskable interrupt pin (NMI). This is an asynchronous interrupt and can be used to wake-up the device from
any sleep mode. See “Additional Features” on page 250
Each interrupt source has an interrupt flag associated with it. The interrupt flag in the Interrupt Flag Status and Clear
register (INTFLAG) is set when an interrupt condition occurs (NMIFLAG for NMI). Each interrupt, except NMI, can be
individually enabled by writing a one to the corresponding bit in the Interrupt Enable Set register (INTENSET), and
disabled by writing a one to the corresponding bit in the Interrupt Enable Clear register (INTENCLR). An interrupt request
is generated when the interrupt flag is set and the corresponding interrupt is enabled. The interrupt request remains
active until the interrupt flag is cleared, the interrupt is disabled or the EIC is reset. See the INTFLAG register for details
on how to clear interrupt flags. The EIC has one common interrupt request line for all the interrupt sources (except the
NMI interrupt request line). Refer to “Processor and Architecture” on page 29 for details. The user must read the
INTFLAG (or NMIFLAG) register to determine which interrupt condition is present.
Note that interrupts must be globally enabled for interrupt requests to be generated. Refer to “Processor and
Architecture” on page 29 for details.
19.6.6 Events
The EIC can generate the following output events:
z
External event from pin (EXTINTx).
Writing a one to an Event Output Control register (EVCTRLEXTINTEO) enables the corresponding output event. Writing
a zero to this bit disables the corresponding output event. Refer to “EVSYS – Event System” on page 313 for details on
configuring the Event System.
When the condition on pin EXTINTx matches the configuration in the CONFIGy register, the corresponding event is
generated, if enabled.
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19.6.7 Sleep Mode Operation
In sleep modes, an EXTINTx pin can wake up the device if the corresponding condition matches the configuration in
CONFIGy register. Writing a one to a Wake-Up Enable bit (WAKEUP.WAKEUPEN[x]) enables the wake-up from pin
EXTINTx. Writing a zero to a Wake-Up Enable bit (WAKEUP.WAKEUPEN[x]) disables the wake-up from pin EXTINTx.
Using WAKEUPEN[x]=1 with INTENSET=0 is not recommended.
Figure 19-3. Wake-Up Operation Example (High-Level Detection, No Filter, WAKEUPEN[x]=1)
CLK_EIC_APB
EXTINTx
intwake_extint[x]
intreq_extint[x]
clear INTFLAG.EXTINT[x]
return to sleep mode
19.6.8 Synchronization
Due to the asynchronicity between CLK_EIC_APB and GCLK_EIC, some registers must be synchronized when
accessed. A register can require:
z
Synchronization when written
z
Synchronization when read
z
Synchronization when written and read
z
No synchronization
When executing an operation that requires synchronization, the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set immediately, and cleared when synchronization is complete.
If an operation that requires synchronization is executed while STATUS.SYNCBUSY is one, the bus will be stalled. All
operations will complete successfully, but the CPU will be stalled, and interrupts will be pending as long as the bus is
stalled.
The following bits need synchronization when written:
z
Software Reset bit in the Control register (CTRL.SWRST)
z
Enable bit in the Control register (CTRL.ENABLE)
No register needs synchronization when written.
No register needs synchronization when read.
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19.7
Register Summary
Table 19-3. Register Summary
Name
Bit
Pos.
0x00
CTRL
7:0
0x01
STATUS
7:0
0x02
NMICTRL
7:0
0x03
NMIFLAG
7:0
Offset
ENABLE
NMIFILTEN
0x04
7:0
EXTINTEO[7:0]
15:8
EXTINTEO[15:8]
EVCTRL
23:16
0x07
31:24
0x08
7:0
EXTINT[7:0]
15:8
EXTINT[15:8]
0x09
0x0A
INTENCLR
23:16
0x0B
31:24
0x0C
7:0
EXTINT[7:0]
15:8
EXTINT[15:8]
0x0D
0x0E
INTENSET
23:16
0x0F
31:24
0x10
7:0
EXTINT[7:0]
15:8
EXTINT[15:8]
0x11
0x12
INTFLAG
0x13
23:16
31:24
0x14
7:0
WAKEUPEN[7:0]
0x15
15:8
WAKEUPEN[15:8]
0x16
NMISENSE[2:0]
NMI
0x05
0x06
WAKEUP
23:16
0x17
31:24
0x18
7:0
FILTEN1
SENSE1[2:0]
FILTEN0
SENSE0[2:0]
15:8
FILTEN3
SENSE3[2:0]
FILTEN2
SENSE2[2:0]
0x19
0x1A
CONFIG0
23:16
FILTEN5
SENSE5[2:0]
FILTEN4
SENSE4[2:0]
0x1B
31:24
FILTEN7
SENSE7[2:0]
FILTEN6
SENSE6[2:0]
0x1C
7:0
FILTEN9
SENSE9[2:0]
FILTEN8
SENSE8[2:0]
0x1D
0x1E
0x1F
SWRST
SYNCBUSY
CONFIG1
15:8
FILTEN11
SENSE11[2:0]
FILTEN10
SENSE10[2:0]
23:16
FILTEN13
SENSE13[2:0]
FILTEN12
SENSE12[2:0]
31:24
FILTEN15
SENSE15[2:0]
FILTEN14
SENSE14[2:0]
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19.8
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-protected property in each individual register description. Refer to “Register Access Protection” on page 248 for
details.
Some registers require synchronization when read and/or written. Synchronization is denoted by the Synchronized
property in each individual register description. Refer to “Synchronization” on page 251 for details.
Some registers are enable-protected, meaning they can be written only when the EIC is disabled. Enable-protection is
denoted by the Enabled-Protected property in each individual register description.
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19.8.1 Control
Name:
CTRL
Offset:
0x00
Reset:
0x00
Property:
Write-Protected,Write-Synchronized
Bit
7
6
5
4
3
2
1
0
ENABLE
SWRST
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – ENABLE: Enable
0: The EIC is disabled.
1: The EIC is enabled.
Due to synchronization, there is delay from writing CTRL.ENABLE until the peripheral is enabled/disabled. The
value written to CTRL.ENABLE will read back immediately, and the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set. STATUS.SYNCBUSY will be cleared when the operation is complete.
z
Bit 0 – SWRST: Software Reset
0: There is no ongoing reset operation.
1: The reset operation is ongoing.
Writing a zero to this bit has no effect.
Writing a one to this bit resets all registers in the EIC to their initial state, and the EIC will be disabled.
Writing a one to CTRL.SWRST will always take precedence, meaning that all other writes in the same write operation will be discarded.
Due to synchronization, there is a delay from writing CTRL.SWRST until the reset is complete. CTRL.SWRST and
STATUS.SYNCBUSY will both be cleared when the reset is complete.
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19.8.2 Status
Name:
STATUS
Offset:
0x01
Reset:
0x00
Property:
-
Bit
7
6
5
4
3
2
1
0
SYNCBUSY
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bit 7 – SYNCBUSY: Synchronization Busy
This bit is cleared when the synchronization of registers between the clock domains is complete.
This bit is set when the synchronization of registers between clock domains is started.
z
Bits 6:0 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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19.8.3 Non-Maskable Interrupt Control
Name:
NMICTRL
Offset:
0x02
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
NMIFILTEN
1
0
NMISENSE[2:0]
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 3 – NMIFILTEN: Non-Maskable Interrupt Filter Enable
0: NMI filter is disabled.
1: NMI filter is enabled.
z
Bits 2:0 – NMISENSE: Non-Maskable Interrupt Sense
These bits define on which edge or level the NMI triggers.
Table 19-4. NMI Sense Configuration
NMISENSE
Name
Description
0x0
NONE
No detection
0x1
RISE
Rising-edge detection
0x2
FALL
Falling-edge detection
0x3
BOTH
Both-edges detection
0x4
HIGH
High-level detection
0x5
LOW
Low-level detection
0x6-0x7
-
Reserved
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19.8.4 Non-Maskable Interrupt Flag Status and Clear
Name:
NMIFLAG
Offset:
0x03
Reset:
0x00
Property:
-
Bit
7
6
5
4
3
2
1
0
NMI
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – NMI: Non-Maskable Interrupt
This flag is cleared by writing a one to it.
This flag is set when the NMI pin matches the NMI sense configuration, and will generate an interrupt request.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the non-maskable interrupt flag.
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19.8.5 Event Control
Name:
EVCTRL
Offset:
0x04
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
EXTINTEO[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
EXTINTEO[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 31:16 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 15:0 – EXTINTEO: External Interrupt x Event Output Enable
These bits indicate whether the event associated with the EXTINTx pin is enabled or not to generated for every
detection.
0: Event from pin EXTINTx is disabled.
1: Event from pin EXTINTx is enabled.
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19.8.6 Interrupt Enable Clear
This register allows the user to disable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Set register (INTENSET).
Name:
INTENCLR
Offset:
0x08
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
EXTINT[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
EXTINT[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 31:16 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 15:0 – EXTINT: External Interrupt x Enable
0: The external interrupt x is disabled.
1: The external interrupt x is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the External Interrupt x Enable bit, which enables the external interrupt.
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19.8.7 Interrupt Enable Set
This register allows the user to enable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Clear (INTENCLR) register.
Name:
INTENSET
Offset:
0x0C
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
EXTINT[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
EXTINT[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 31:16 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 15:0 – EXTINT: External Interrupt x Enable
0: The external interrupt x is disabled.
1: The external interrupt x is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the External Interrupt x Enable bit, which enables the external interrupt.
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19.8.8 Interrupt Flag Status and Clear
Name:
INTFLAG
Offset:
0x10
Reset:
0x00000000
Property:
-
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
EXTINT[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
EXTINT[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 31:16 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 15:0 – EXTINT: External Interrupt x
This flag is cleared by writing a one to it.
This flag is set when EXTINTx pin matches the external interrupt sense configuration and will generate an interrupt
request if INTENCLR/SET.EXTINT[x] is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the External Interrupt x flag.
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19.8.9 Wake-Up Enable
Name:
WAKEUP
Offset:
0x14
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
WAKEUPEN[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
WAKEUPEN[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 31:16 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 15:0 – WAKEUPEN: External Interrupt x Wake-up Enable
This bit enables or disables wake-up from sleep modes when the EXTINTx pin matches the external interrupt
sense configuration.
0: Wake-up from the EXTINTx pin is disabled.
1: Wake-up from the EXTINTx pin is enabled.
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19.8.10 Configuration n
Name:
CONFIGn
Offset:
0x18+n*0x4 [n=0..1]
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
FILTEN7
Access
29
28
SENSE7[2:0]
27
26
FILTEN6
25
24
SENSE6[2:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
FILTEN5
Access
SENSE5[2:0]
FILTEN4
SENSE4[2:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
FILTEN3
Access
SENSE3[2:0]
FILTEN2
SENSE2[2:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
FILTEN1
Access
Reset
z
SENSE1[2:0]
FILTEN0
SENSE0[2:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31, 27, 23, 19, 15, 11, 7, 3 – FILTENx [x=7..0]: Filter x Enable
0: Filter is disabled for EXTINT[n*8+x] input.
1: Filter is enabled for EXTINT[n*8+x] input.
z
Bits 30:28, 26:24, 22:20, 18:16, 14:12, 10:8, 6:4, 2:0 – SENSEx[2:0] [x=7..0]: Input Sense x Configuration
These bits define on which edge or level the interrupt or event for EXTINT[n*8+x] will be generated.
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Table 19-5. Sense Configuration
SENSE
Name
Description
0x0
NONE
No detection
0x1
RISE
Rising-edge detection
0x2
FALL
Falling-edge detection
0x3
BOTH
Both-edges detection
0x4
HIGH
High-level detection
0x5
LOW
Low-level detection
0x6-0x7
-
Reserved
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20.
NVMCTRL – Non-Volatile Memory Controller
20.1
Overview
Non-volatile memory (NVM) is a reprogrammable flash memory that retains program and data storage even with power
off. The NVM Controller (NVMCTRL) connects to the AHB and APB bus interfaces for system access to the NVM block.
The AHB interface is used for reads and writes to the NVM block, while the APB interface is used for commands and
configuration.
20.2
Features
z 32-bit AHB interface for reads and writes
z All NVM sections are memory mapped to the AHB, including calibration and system configuration
z 32-bit APB interface for commands and control
z Programmable wait states for read optimization
z 16 regions can be individually protected or unprotected
z Additional protection for boot loader
z Supports device protection through a security bit
z Interface to Power Manager for power-down of flash blocks in sleep modes
z Can optionally wake up on exit from sleep or on first access
z Direct-mapped cache
20.3
Block Diagram
Figure 20-1. Block Diagram
NVMCTRL
AHB
Cache
NVM Interface
APB
20.4
NVM Block
Command and
Control
Signal Description
Not applicable
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20.5
Product Dependencies
In order to use this module, other parts of the system must be configured correctly, as described below.
20.5.1 Power Management
The NVMCTRL will continue to operate in any sleep mode where the selected source clock is running. The NVMCTRL’s
interrupts can be used to wake up the device from sleep modes. Refer to “PM – Power Manager” on page 107 for details
on the different sleep modes.
The Power Manager will automatically put the NVM block into a low-power state when entering sleep mode. This is
based on the Control B register (CTRLB - refer to CTRLB) SLEEPPRM bit setting. Read the CTRLB register description
for more details.
20.5.2 Clocks
Two synchronous clocks are used by the NVMCTRL. One is provided by the AHB bus (CLK_NVMCTRL_AHB) and the
other is provided by the APB bus (CLK_NVMCTRL_APB). For higher system frequencies, a programmable number of
wait states can be used to optimize performance. When changing the AHB bus frequency, the user must ensure that the
NVM Controller is configured with the proper number of wait states. Refer to the “Electrical Characteristics” on page 571
for the exact number of wait states to be used for a particular frequency range.
20.5.3 Interrupts
The NVM Controller interrupt request line is connected to the interrupt controller. Using the NVMCTRL interrupt requires
the interrupt controller to be programmed first.
Refer to “Nested Vector Interrupt Controller” on page 30 for details.
20.5.4 Debug Operation
When an external debugger forces the CPU into debug mode, the peripheral continues normal operation.
Access to the NVM block can be protected by the security bit. In this case, the NVM block will not be accessible. See
“Security Bit” on page 271 for details.
20.5.5 Register Access Protection
All registers with write-access are optionally write-protected by the Peripheral Access Controller (PAC), except the
following registers:
z
Interrupt Flag Status and Clear register (INTFLAG - refer to INTFLAG)
z
Status register (STATUS - refer to STATUS)
Write-protection is denoted by the Write-Protected property in the register description. Write-protection does not apply for
accesses through an external debugger.
When the CPU is halted in debug mode, all write-protection is automatically disabled. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
20.5.6 Analog Connections
Not applicable.
20.6
Functional Description
20.6.1 Principle of Operation
The NVM Controller is a slave on the AHB and APB buses. It responds to commands, read requests and write requests,
based on user configuration.
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20.6.2 Basic Operations
20.6.2.1 Initialization
After power up, the NVM Controller goes through a power-up sequence. During this time, access to the NVM Controller
from the AHB bus is halted. Upon power-up completion, the NVM Controller is operational without any need for user
configuration.
20.6.2.2 Enabling, Disabling and Resetting
Not applicable.
20.6.3 Memory Organization
Refer to “Physical Memory Map” on page 25 for memory sizes and addresses for each device.
The NVM is organized into rows, where each row contains four pages, as shown in Figure 20-2. The NVM has a rowerase granularity, while the write granularity is by page. In other words, a single row erase will erase all four pages in the
row, while four write operations are used to write the complete row.
Figure 20-2. Row Organization
Row n
Page (n * 4) + 3
Page (n * 4) + 2
Page (n * 4) + 1
Page (n * 4) + 0
The NVM block contains a calibration and auxiliary space that is memory mapped. Refer to Figure 20-3 for details.
The calibration and auxiliary space contains factory calibration and system configuration information. This space can be
read from the AHB bus in the same way as the main NVM main address space.
In addition, a boot loader section can be allocated at the beginning of the main array, and an EEPROM emulation area
can be allocated at the end of the NVM main address space.
Figure 20-3. NVM Memory Organization
Calibration and
auxiliary space
NVM Base Address + 0x00800000
NVM Base Address + NVM size
NVM Main
Address Space
NVM Base Address
The lower rows in the NVM main address space can be allocated as a boot loader section by using the BOOTPROT
fuses, and the upper rows can be allocated to EEPROM emulation, as shown in Figure 20-4. The boot loader section is
protected by the lock bit(s) corresponding to this address space and by the BOOTPROT[2:0] fuse. The EEPROM rows
can be written regardless of the region lock status. The number of rows protected by BOOTPROT and the number of
rows allocated to EEPROM emulation are given in Table 20-2 and Table 20-3, respectively.
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Figure 20-4. EEPROM Emulation and Boot Loader Allocation
NVM Base Address + NVM size
EEPROM Emulation
allocation
NVM Base Address + NVM size - EEPROM size
Program
allocation
NVM Base Address + BOOTPROT size
BOOT
allocation
NVM Base Address
20.6.4 Region Lock Bits
The NVM block is grouped into 16 equally sized regions. The region size is dependent on the flash memory size, and is
given in the table below. Each region has a dedicated lock bit preventing writing and erasing pages in the region. After
production, all regions will be unlocked.
Table 20-1. Region Size
Memory Size [KB]
Region Size [KB]
256
16
128
8
64
4
32
2
To lock or unlock a region, the Lock Region and Unlock Region commands are provided. Writing one of these commands
will temporarily lock/unlock the region containing the address loaded in the ADDR register. ADDR can be written by
software, or the automatically loaded value from a write operation can be used. The new setting will stay in effect until the
next reset, or the setting can be changed again using the lock and unlock commands. The current status of the lock can
be determined by reading the LOCK register.
To change the default lock/unlock setting for a region, the user configuration section of the auxiliary space must be
written using the Write Auxiliary Page command. Writing to the auxiliary space will take effect after the next reset.
Therefore, a boot of the device is needed for changes in the lock/unlock setting to take effect. See “Physical Memory
Map” on page 25 for calibration and auxiliary space address mapping.
20.6.5 Command and Data Interface
The NVM Controller is addressable from the APB bus, while the NVM main address space is addressable from the AHB
bus. Read and automatic page write operations are performed by addressing the NVM main address space directly,
while other operations such as manual page writes and row erase must be performed by issuing commands through the
NVM Controller.
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To issue a command, the CTRLA.CMD bits must be written along with the CTRLA.CMDEX value. When a command is
issued, INTFLAG.READY will be cleared until the command has completed. Any commands written while
INTFLAG.READY is low will be ignored. Read the CTRLA register description for more details.
The CTRLB register must be used to control the power reduction mode, read wait states and the write mode.
20.6.5.1 NVM Read
Reading from the NVM main address space is performed via the AHB bus by addressing the NVM main address space
or auxiliary address space directly. Read data is available after the configured number of read wait states (CTRLB.RWS)
set in the NVM Controller, has passed.
The number of cycles data are delayed to the AHB bus is determined by the read wait states. Examples of using zero
and one wait states are shown in Figure 20-5.
Figure 20-5. Read Wait State Examples
0 Wait States
AHB Command
Rd 0
Idle
Rd 1
AHB Slave Ready
Data 0
AHB Slave Data
Data 1
1 Wait State
AHB Command Rd 0
Rd 1
Idle
AHB Slave Ready
AHB Slave Data
Data 0
Data 1
20.6.5.2 NVM Write
The NVM Controller requires that an erase must be done before programming. The entire NVM main address space can
be erased by a debugger Chip Erase command. Alternatively, rows can be individually erased by the Erase Row
command.
After programming, the region that the page resides in can be locked to prevent spurious write or erase sequences.
Locking is performed on a per-region basis, and so locking a region locks all pages inside the region.
Data to be written to the NVM block are first written and stored in an internal buffer called the page buffer. The page
buffer contains the same number of bytes as an NVM page. Writes to the page buffer must be 16 or 32 bits. 8-bit writes
to the page buffer is not allowed, and will cause a system exception.
Writing to the NVM block via the AHB bus is performed by a load operation to the page buffer. For each AHB bus write,
the address is stored in the ADDR register. After the page buffer has been loaded with the required number of bytes, the
page can be written to the addressed location by setting CMD to Write Page and setting the key value to CMDEX. The
LOAD bit in the STATUS register indicates whether the page buffer has been loaded or not. Before writing the page to
memory, the accessed row must be erased.
By default, automatic page writes are enabled (MANW=0). This will trigger a write operation to the page addressed by
ADDR when the last location of the page is written.
Because the address is automatically stored in ADDR during the I/O bus write operation, the last given address will be
present in the ADDR register. There is no need to load the ADDR register manually, unless a different page in memory is
to be written.
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Procedure for Manual Page Writes (MANW=1)
The row to be written must be erased before the write command is given.
z
Write to the page buffer by addressing the NVM main address space directly
z
Write the page buffer to memory: CMD=Write Page and CMDEX
z
The READY bit in the INTFLAG register will be low while programming is in progress, and access through the AHB
will be stalled
Procedure for Automatic Page Writes (MANW=0)
The row to be written must be erased before the last write to the page buffer is performed.
Note that partially written pages must be written with a manual write.
z
Write to the page buffer by addressing the NVM main address space directly.
z
z
When the last location in the page buffer is written, the page is automatically written to NVM main address
space.
INTFLAG.READY will be zero while programming is in progress and access through the AHB will be stalled.
20.6.5.3 Page Buffer Clear
The page buffer is automatically cleared to all ones after a page write is performed. If a partial page has been written and
it is desired to clear the contents of the page buffer, the Page Buffer Clear command can be used.
20.6.5.4 Erase Row
Before a page can be written, the row that contains the page must be erased. The Erase Row command can be used to
erase the desired row. Erasing the row sets all bits to one. If the row resides in a region that is locked, the erase will not
be performed and the Lock Error bit in the Status register (STATUS.LOCKE) will be set.
Procedure for Erase Row
z
Write the address of the row to erase ADDR. Any address within the row can be used.
z
Issue an Erase Row command.
20.6.5.5 Lock and Unlock Region
These commands are used to lock and unlock regions as detailed in section “Region Lock Bits” on page 268.
20.6.5.6 Set and Clear Power Reduction Mode
The NVM Controller and block can be taken in and out of power reduction mode through the set and clear power
reduction mode commands. When the NVM Controller and block are in power reduction mode, the Power Reduction
Mode bit in the Status register (STATUS.PRM) is set.
20.6.6 NVM User Configuration
The NVM user configuration resides in the auxiliary space. See “Physical Memory Map” on page 25 for calibration and
auxiliary space address mapping.
The bootloader resides in the main array starting at offset zero. The allocated boot loader section is protected against
write.
Table 20-2. Boot Loader Size
BOOTPROT [2:0]
Rows Protected by BOOTPROT
Boot Loader Size in Bytes
7
None
0
6
2
512
5
4
1024
4
8
2048
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BOOTPROT [2:0]
Rows Protected by BOOTPROT
Boot Loader Size in Bytes
3
16
4096
2
32
8192
1
64
16384
0
128
32768
The EEPROM bits indicates the Flash size reserved for EEPROM emulation according to the Table 20-3. EEPROM
resides in the upper rows of the NVM main address space and are writable, regardless of the region lock status.
Table 20-3. Flash size for EEPROM emulation
Note:
EEPROM[2:0]
Rows Allocated to EEPROM
EEPROM Size in Bytes for EEPROM emulation(1)
7
None
0
6
1
256
5
2
512
4
4
1024
3
8
2048
2
16
4096
1
32
8192
0
64
16384
1.
the actual size of the EEPROM depends on the emulation software. For more information see Application Note AT03265
20.6.7 Security Bit
The security bit allows the entire chip to be locked from external access for code security. The security bit can be written
by a dedicated command, Set Security Bit (SSB). Once set, the only way to clear the security bit is through a debugger
Chip Erase command. After issuing the SSB command, the PROGE error bit can be checked. Refer to “DSU – Device
Service Unit” on page 43 for details.
20.6.8 Cache
The NVM Controller cache reduces the device power consumption and improves system performance when wait states
are required. It is a direct-mapped cache that implements 8 lines of 64 bits (i.e., 64 bytes). NVM Controller cache can be
enabled by writing a zero in the CACHEDIS bit in the CTRLB register (CTRLB.CACHEDIS). Cache can be configured to
three different modes using the READMODE bit group in the CTRLB register. Refer to CTRLB register description for
more details. The INVALL command can be issued through the CTRLA register to invalidate all cache lines. Commands
affecting NVM content automatically invalidate cache lines.
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20.7
Offset
Register Summary
Name
0x00
Bit Pos.
7:0
CMD[6:0]
CTRLA
0x01
15:8
0x2
Reserved
0x3
Reserved
0x04
7:0
0x05
CMDEX[7:0]
MANW
RWS[3:0]
15:8
SLEEPPRM[1:0]
CTRLB
CACHEDIS
0x06
23:16
0x07
31:24
0x08
7:0
NVMP[7:0]
15:8
NVMP[15:8]
0x09
0x0A
PARAM
0x0B
23:16
READMODE[1:0]
PSZ[2:0]
31:24
0x0C
INTENCLR
0x0D
Reserved
0x0E
Reserved
0x0F
Reserved
0x10
INTENSET
0x11
Reserved
0x12
Reserved
0x13
Reserved
0x14
INTFLAG
0x15
Reserved
0x16
Reserved
0x17
Reserved
0x18
7:0
ERROR
READY
7:0
ERROR
READY
7:0
ERROR
READY
LOAD
PRM
7:0
NVME
LOCKE
PROGE
STATUS
0x19
15:8
0x1A
Reserved
0x1B
Reserved
0x1C
0x1D
0x1E
ADDR
0x1F
SB
7:0
ADDR[7:0]
15:8
ADDR[15:8]
23:16
ADDR[21:16]
31:24
0x20
7:0
LOCK[7:0]
15:8
LOCK[15:8]
LOCK
0x21
0x22
Reserved
0x23
Reserved
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20.8
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-Protected property in each individual register description. Refer to the “Register Access Protection” on page
266 and the “PAC – Peripheral Access Controller” on page 34 for details.
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20.8.1 Control A
Name:
CTRLA
Offset:
0x00
Reset:
0x0000
Property:
Write-Protected
Bit
15
14
13
12
11
10
9
8
CMDEX[7:0]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
CMD[6:0]
Access
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 15:8 – CMDEX: Command Execution
This bit group should be written with the key value 0xA5 to enable the command written to CMD to be executed. If
the bit group is written with a different key value, the write is not performed and the PROGE status bit is set.
PROGE is also set if the a previously written command is not complete.
The key value must be written at the same time as CMD. If a command is issued through the APB bus on the
same cycle as an AHB bus access, the AHB bus access will be given priority. The command will then be executed
when the NVM block and the AHB bus are idle.
The READY status must be one when the command is issued.
Bit 0 of the CMDEX bit group will read back as one until the command is issued.
z
Bit 7 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 6:0 – CMD: Command
These bits define the command to be executed when the CMDEX key is written, as shown in Table 20-4.
Table 20-4. Command Bit Description
CMD[4:0]
Group Configuration
Description
0x00-0x01
-
Reserved
0x02
ER
Erase Row - Erases the row addressed by the ADDR register.
0x03
-
Reserved
0x04
WP
Write Page - Writes the contents of the page buffer to the page addressed
by the ADDR register.
0x05
EAR
Erase Auxiliary Row - Erases the auxiliary row addressed by the ADDR
register. This command can be given only when the security bit is not set
and only to the user configuration row.
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Table 20-4. Command Bit Description (Continued)
CMD[4:0]
Group Configuration
Description
0x06
WAP
Write Auxiliary Page - Writes the contents of the page buffer to the page
addressed by the ADDR register. This command can be given only when the
security bit is not set and only to the user configuration row.
0x07-0x3F
-
Reserved
0x40
LR
Lock Region - Locks the region containing the address location in the ADDR
register.
0x41
UR
Unlock Region - Unlocks the region containing the address location in the
ADDR register.
0x42
SPRM
Sets the power reduction mode.
0x43
CPRM
Clears the power reduction mode.
0x44
PBC
Page Buffer Clear - Clears the page buffer.
0x45
SSB
Set Security Bit - Sets the security bit by writing 0x00 to the first byte in the
lockbit row.
0x46
INVALL
Invalidates all cache lines.
0x46-0x7F
-
Reserved
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20.8.2 Control B
Name:
CTRLB
Offset:
0x04
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
CACHEDIS
READMODE[1:0]
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
SLEEPPRM[1:0]
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
MANW
Access
Reset
RWS[3:0]
R/W
R
R
R/W
R/W
R/W
R/W
R
0
0
0
0
0
0
0
0
z
Bits 31:19 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 18 – CACHEDIS: Cache Disable
This bit is used to disable the cache.
0: The cache is enabled.
1: The cache is disabled.
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z
Bits 17:16 – READMODE: NVMCTRL Read Mode
READMODE
Name
Description
NO_MISS_PENALTY
The NVM Controller (cache system) does not insert wait states on
a cache miss. Gives the best system performance.
LOW_POWER
Reduces power consumption of the cache system, but inserts a
wait state each time there is a cache miss. This mode may not be
relevant if CPU performance is required, as the application will be
stalled and may lead to increase run time.
0x2
DETERMINISTIC
The cache system ensures that a cache hit or miss takes the same
amount of time, determined by the number of programmed flash
wait states. This mode can be used for real-time applications that
require deterministic execution timings.
0x3
Reserved
0x0
0x1
z
Bits 15:10 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 9:8 – SLEEPPRM: Power Reduction Mode during Sleep
Indicates the power reduction mode during sleep.
Table 20-5. Table 1-7. Power Reduction Mode during Sleep
SLEEPPRM[1:0]
z
Name
Description
0x0
WAKEONACCESS
NVM block enters low-power mode when entering sleep.
NVM block exits low-power mode upon first access.
0x1
WAKEUPINSTANT
NVM block enters low-power mode when entering sleep.
NVM block exits low-power mode when exiting sleep.
0x2
Reserved
0x3
DISABLED
Auto power reduction disabled.
Bit 7 – MANW: Manual Write
0: Writing to the last word in the page buffer will automatically initiate a write operation to the page addressed in
the Address (ADDR) register. This includes writes to memory and auxiliary rows.
1: Write commands must be issued through the Command bit group in the Control A register(CTRLA.CMD).
z
Bits 6:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 4:1 – RWS: NVM Read Wait States
These bits give the number of wait states for a read operation. Zero indicates zero wait states, one indicates one
wait state, etc., up to 15 wait states.
This register is initialized to 0 wait states. Software can change this value based on the NVM access time and system frequency.
z
Bit 0 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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20.8.3 NVM Parameter
Name:
PARAM
Offset:
0x08
Reset:
0x000XXXXX
Property:
–
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
PSZ[2:0]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
X
X
X
Bit
15
14
13
12
11
10
9
8
NVMP[15:8]
Access
R
R
R
R
R
R
R
R
Reset
X
X
X
X
X
X
X
X
Bit
7
6
5
4
3
2
1
0
R
R
X
X
NVMP[7:0]
Access
R
R
R
R
R
Reset
X
X
X
X
X
X
z
Bits 31:19 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 18:16 – PSZ: Page Size
Indicates the page size. Not all device families will provide all the page sizes indicated in the table.
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Table 20-6. Page Size
z
PSZ[2:0]
Name
Description
0x0
8
8 bytes
0x1
16
16 bytes
0x2
32
32 bytes
0x3
64
64 bytes
0x4
128
128 bytes
0x5
256
256 bytes
0x6
512
512 bytes
0x7
1024
1024 bytes
Bits 15:0 – NVMP: NVM Pages
Indicates the number of pages in the NVM main address space.
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20.8.4 Interrupt Enable Clear
This register allows the user to disable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Set register (INTENSET).
Name:
INTENCLR
Offset:
0x0C
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
ERROR
READY
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – ERROR: Error Interrupt Enable
0: Error interrupt is disabled
1: Error interrupt is enabled
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Error Interrupt Enable bit, which disables the Error interrupt.
z
Bit 0 – READY: NVM Ready Interrupt Enable
0: NVM Ready interrupt is disabled
1: NVM Ready interrupt is enabled
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the NVM Ready Interrupt Enable bit, which disables the NVM Ready interrupt.
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20.8.5 Interrupt Enable Set
This register allows the user to enable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Clear register (INTENCLR).
Name:
INTENSET
Offset:
0x10
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
ERROR
READY
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – ERROR: Error Interrupt Enable
Writing a zero to this bit has no effect.
Writing a one to this bit sets the ERROR interrupt enable.
This bit will read as the current value of the ERROR interrupt enable.
z
Bit 0 – READY: NVM Ready Interrupt Enable
Writing a zero to this bit has no effect.
Writing a one to this bit sets the READY interrupt enable.
This bit will read as the current value of the READY interrupt enable.
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20.8.6 Interrupt Flag Status and Clear
Name:
INTFLAG
Offset:
0x14
Reset:
0x00
Property:
–
Bit
7
6
5
4
3
2
1
0
ERROR
READY
Access
R
R
R
R
R
R
R/W
R
Reset
0
0
0
0
0
0
0
0
z
Bits 7:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – ERROR: Error
This flag is set on the occurrence of an NVME, LOCKE or PROGE error.
0: No errors have been received since the last clear.
1: At least one error has occurred since the last clear.
This bit can be cleared by writing a one to its bit location.
z
Bit 0 – READY: NVM Ready
0: The NVM controller is busy programming or erasing.
1: The NVM controller is ready to accept a new command.
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20.8.7 Status
Name:
STATUS
Offset:
0x18
Reset:
0x0X00
Property:
–
Bit
15
14
13
12
11
10
9
8
SB
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
X
Bit
7
6
5
4
3
2
1
0
NVME
LOCKE
PROGE
LOAD
PRM
Access
R
R
R
R/W
R/W
R/W
R/W
R
Reset
0
0
0
0
0
0
0
0
z
Bits 15:9 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 8 – SB: Security Bit Status
0: The Security bit is inactive.
1: The Security bit is active.
z
Bits 7:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 4 – NVME: NVM Error
0: No programming or erase errors have been received from the NVM controller since this bit was last cleared.
1: At least one error has been registered from the NVM Controller since this bit was last cleared.
This bit can be cleared by writing a one to its bit location.
z
Bit 3 – LOCKE: Lock Error Status
0: No programming of any locked lock region has happened since this bit was last cleared.
1: Programming of at least one locked lock region has happened since this bit was last cleared.
This bit can be cleared by writing a one to its bit location.
z
Bit 2 – PROGE: Programming Error Status
0: No invalid commands or bad keywords were written in the NVM Command register since this bit was last
cleared.
1: An invalid command and/or a bad keyword was/were written in the NVM Command register since this bit was
last cleared.
This bit can be cleared by writing a one to its bit location.
z
Bit 1 – LOAD: NVM Page Buffer Active Loading
This bit indicates that the NVM page buffer has been loaded with one or more words. Immediately after an NVM
load has been performed, this flag is set, and it remains set until a page write or a page buffer clear (PBCLR) command is given.
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This bit can be cleared by writing a one to its bit location.
z
Bit 0 – PRM: Power Reduction Mode
This bit indicates the current NVM power reduction state. The NVM block can be set in power reduction mode in
two ways: through the command interface or automatically when entering sleep with SLEEPPRM set accordingly.
PRM can be cleared in three ways: through AHB access to the NVM block, through the command interface (SPRM
and CPRM) or when exiting sleep with SLEEPPRM set accordingly.
0: NVM is not in power reduction mode.
1: NVM is in power reduction mode.
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20.8.8 Address
Name:
ADDR
Offset:
0x1C
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
ADDR[21:16]
Access
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
ADDR[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ADDR[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 31:22 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 21:0 – ADDR: NVM Address
ADDR drives the hardware (16-bit) address to the NVM when a command is executed using CMDEX. 8-bit
addresses must be shifted one bit to the right before writing to this register.
This register is automatically updated when writing to the page buffer, and can also be manually written. This register holds the address offset for the section addressed.
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20.8.9 Lock Section
Name:
LOCK
Offset:
0x20
Reset:
0xXXXX
Property:
–
Bit
15
14
13
12
11
10
9
8
LOCK[15:8]
Access
R
R
R
R
R
R
R
R
Reset
X
X
X
X
X
X
X
X
Bit
7
6
5
4
3
2
1
0
LOCK[7:0]
Access
R
R
R
R
R
R
R
R
Reset
X
X
X
X
X
X
X
X
z
Bits 15:0 – LOCK: Region Lock Bits
In order to set or clear these bits, the CMD register must be used.
0: The corresponding lock region is locked.
1: The corresponding lock region is not locked.
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21.
PORT
21.1
Overview
The Port (PORT) controls the I/O pins of the microcontroller. The I/O pins are organized in a series of groups, collectively
referred to as a line bundle, and each group can have up to 32 pins that can be configured and controlled individually or
as a group. Each pin may either be used for general-purpose I/O under direct application control or assigned to an
embedded device peripheral. When used for general-purpose I/O, each pin can be configured as input or output, with
highly configurable driver and pull settings.
All I/O pins have true read-modify-write functionality when used for general-purpose I/O; the direction or the output value
of one or more pins may be changed (set, reset or toggled) without unintentionally changing the state of any other pins in
the same line bundle via a single, atomic 8-, 16- or 32-bit write.
The PORT is connected to the high-speed bus matrix through an AHB/APB bridge. The Pin Direction, Data Output Value
and Data Input Value registers may also be accessed using the low-latency CPU local bus (IOBUS; ARM® single-cycle
I/O port).
21.2
Features
z Selectable input and output configuration individually for each pin
z Software-controlled multiplexing of peripheral functions on I/O pins
z Flexible pin configuration through a dedicated Pin Configuration register
z Configurable output driver and pull settings:
z
Totem-pole (push-pull)
Pull configuration
z Driver strength
z
z Configurable input buffer and pull settings:
z
Internal pull-up or pull-down
Input sampling criteria
z Input buffer can be disabled if not needed for lower power consumption
z
z Read-modify-write support for pin configuration, output value and pin direction
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21.3
Block Diagram
Figure 21-1. PORT Block Diagram
PORT
Peripheral Mux Select
Control
Status
Port Line
Bundles
IP Line Bundles
PORTMUX
and
Pin Line
Bundles
I/O
PINS
Analog Pin
Connections
PERIPHERALS
Digital Controls of Analog Blocks
ANALOG
BLOCKS
21.4
Signal Description
Signal Name
Type
Description
Pxy
Digital I/O
General-purpose I/O pin y
Refer to “I/O Multiplexing and Considerations” on page 16 for details on the pin mapping for this peripheral. One signal
can be mapped on several pins.
21.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
21.5.1 I/O Lines
The I/O lines of the PORT are mapped to pins of the physical device package according to a simple naming scheme.
Each line bundle of up to 32 pins is assigned a letter identifier, starting with A, that monotonically increases through the
alphabet for each subsequent line bundle. Within each line bundle, each pin is assigned a numerical identifier according
to its bit position.
The resulting PORT pins are mapped as Pxy, where x=A, B, C,… and y=00, 01, …, 31 to uniquely identify each pin in the
device, e.g., PA24, PC03, etc.
Each pin may have one or more peripheral multiplexer settings, which allow the pin to be routed internally to a dedicated
peripheral function. When enabled, the selected peripheral is given control over the output state of the pin, as well as the
ability to read the current physical pin state. Refer to “I/O Multiplexing and Considerations” on page 16 for details.
Device-specific configurations may result in some pins (and the corresponding Pxy pin) not being implemented.
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21.5.2 Power Management
During reset, all PORT lines are configured as inputs with input buffers, output buffers and pull disabled.
If the PORT peripheral is shut down, the latches contained in the pin will retain their current configuration, such as the
output value and pull settings. However, the PORT configuration registers and input synchronizers will lose their
contents, and these will not be restored when PORT is powered up again. The user must, therefore, reconfigure the
PORT peripheral at power up to ensure it is in a well-defined state before use.
The PORT will continue to operate in any sleep mode where the selected module source clock is running.
21.5.3 Clocks
The PORT bus clock (CLK_PORT_APB) can be enabled and disabled in the Power Manager, and the default state of
CLK_PORT_APB can be found in the Peripheral Clock Masking section in the “PM – Power Manager” on page 107.
The PORT is fed by two different clocks: a CPU main clock, which allows the CPU to access the PORT through the lowlatency CPU local bus (IOBUS), and an APB clock, which is a divided clock of the CPU main clock and allows the CPU to
access the PORT registers through the high-speed matrix and the AHB/APB bridge.
IOBUS accesses have priority over APB accesses. The latter must insert wait states in the event of concurrent PORT
accesses.
The PORT input synchronizers use the CPU main clock so that the resynchronization delay is minimized with respect to
the APB clock.
21.5.4 DMA
Not applicable.
21.5.5 Interrupts
Not applicable.
21.5.6 Events
Not applicable.
21.5.7 Debug Operation
When the CPU is halted in debug mode, the PORT continues normal operation. If the PORT is configured in a way that
requires it to be periodically serviced by the CPU through interrupts or similar, improper operation or data loss may result
during debugging.
21.5.8 Register Access Protection
All registers with write-access are optionally write-protected by the Peripheral Access Controller (PAC).
Write-protection is denoted by the Write-Protected property in the register description.
When the CPU is halted in debug mode, all write-protection is automatically disabled.
Write-protection does not apply for accesses through an external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
21.5.9 Analog Connections
Analog functions are connected directly between the analog blocks and the I/O pins using analog buses. However,
selecting an analog peripheral function for a given pin will disable the corresponding digital features of the pin.
21.5.10 CPU Local Bus
The CPU local bus (IOBUS) is an interface that connects the CPU directly to the PORT. It is a single-cycle bus interface,
and does not support wait states. It supports byte, half word and word sizes.
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The CPU accesses the PORT module through the IOBUS when it performs read or write from address 0x60000000. The
PORT register map is equivalent to the one described in the register description section.
This bus is generally used for low latency. The Data Direction (DIR - refer to DIR) and Data Output Value (OUT - refer to
OUT) registers can be read, written, set, cleared or toggled using this bus, and the Data Input Value (IN - refer to IN)
registers can be read.
Since the IOBUS cannot wait for IN register resynchronization, the Control register (CTRL - refer to CTRL) must be
configured to enable continuous sampling of all pins that will need to be read via the IOBUS to prevent stale data from
being read.
21.6
Functional Description
Figure 21-2. Overview of the PORT
...
PADy
PORTx
PULLEN
PULLENy
Pull
Resistor
Port_Mux
APB Bus
PG
OUT
OUTy
3.3V
OE
DIRy
PADy
NG
INEN
INENy
IN
INy
Synchronizer
...
Input to Other Modules
Analog Input/Output
21.6.1 Principle of Operation
The I/O pins of the device are controlled by reads and writes of the PORT peripheral registers. For each port pin, a
corresponding bit in the Data Direction (DIR - refer to DIR) and Data Output Value (OUT - refer to OUT) registers are
used to enable that pin as an output and to define the output state.
The direction of each pin in a port bundle is configured via the DIR register. If a bit in DIR is written to one, the
corresponding pin is configured as an output pin. If a bit in DIR is written to zero, the corresponding pin is configured as
an input pin.
When the direction is set as output, the corresponding bit in the OUT register is used to set the level of the pin. If bit y of
OUT is written to one, pin y is driven high. If bit y of OUT is written to zero, pin y is driven low.
Additional pin configuration can be set by writing to the Pin Configuration (PINCFGy - refer to PINCFGy) registers.
The Data Input Value bit (IN - refer to IN) is used to read the port pin with resynchronization to the PORT clock. By
default, these input synchronizers are clocked only when an input value read is requested in order to reduce power
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consumption. Input value can always be read, whether the pin is configured as input or output, except if digital input is
disabled by writing a zero to the INEN bit in the Pin Configuration registers (PINCFGy).
The PORT also allows peripheral functions to be connected to individual I/O pins by writing a one to the corresponding
PMUXEN bit in the PINCFGy registers and by writing the chosen selection to the Peripheral Multiplexing registers
(PMUXn - refer to PMUXn) for that pin. This will override the connection between the PORT and that I/O pin, and connect
the selected peripheral line bundle to the pin instead of the PORT line bundle.
Each group of up to 32 pins is controlled by a set of registers, as described in Figure 21-3. This set of registers is
duplicated for each group of pins, with increasing base addresses.
Figure 21-3. Overview of the Peripheral Functions Multiplexing
PORT bit y
Port y PINCFG
PMUXEN
Port y
Data+Config
Port y
PMUX[3:0]
PORTMUX
Port y Peripheral
Mux Enable
Port y Line Bundle
0
Port y PMUX Select
Pin y
PIN y
Line Bundle
Periph Line 0
0
Periph Line 1
1
1
Peripheral Line Bundles
to be muxed to Pad y
Periph Line 15
15
21.6.2 Basic Operation
21.6.2.1 Initialization
After reset, all standard-function device I/O pins are connected to the PORT with outputs tri-stated and input buffers
disabled, even if no clocks are running. Specific pins, such as the ones used for connection to a debugger, may be
configured differently, as required by their special function.
21.6.3 Basic Operation
Each I/O pin y can be configured and accessed by reading or writing PORT registers. Because PORT registers are
grouped into sets of registers for each group of up to 32 pins, the base address of the register set for pin y is at byte
address PORT + (y / 32) * 0x80. (y%32) will be used as the index within each register of that register set.
To use pin y as an output, configure it as output by writing the (y%32) bit in the DIR register to one. To avoid disturbing
the configuration of other pins in that group, this can also be done by writing the (y%32) bit in the DIRSET register to one.
The desired output value can be set by writing the (y%32) bit to that value in register OUT.
Similarly, writing an OUTSET bit to one will set the corresponding bit in the OUT register to one, while writing an
OUTCLR bit to one will set it to zero, and writing an OUTTGL bit to one will toggle that bit in OUT.
To use pin y as an input, configure it as input by writing the (y%32) bit in the DIR register to zero. To avoid disturbing the
configuration of other pins in that group, this can also be done by writing the (y%32) bit in DIRCLR register to one. The
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desired input value can be read from the (y%32) bit in register IN as soon as the INEN bit in the Pin Configuration register
(PINCFGy) is written to one. Refer to “I/O Multiplexing and Considerations” on page 16 for details on pin configuration.
By default, the input synchronizer is clocked only when an input read is requested, which will delay the read operation by
two CLK_PORT cycles. To remove that delay, the input synchronizers for each group of eight pins can be configured to
be always active, but this comes at the expense of higher power consumption. This is controlled by writing a one to the
corresponding SAMPLINGn bit group of the CTRL register, where n = (y%32) / 8.
To use pin y as one of the available peripheral functions for that pin, configure it by writing a one to the corresponding
PMUXEN bit of the PINCFGy register. The PINCFGy register for pin y is at byte offset (PINCFG0 + (y%32)).
The peripheral function can be selected by writing to the PMUXO or PMUXE bit group in the PMUXn register. The
PMUXO/PMUXE bit group is at byte offset (PMUX0 + (y%32) / 2), in bits 3:0 if y is even and in bits 7:4 if y is odd.
The chosen peripheral must also be configured and enabled.
21.6.4 I/O Pin Configuration
The Pin Configuration register (PINCFGy) is used for additional I/O pin configuration. A pin can be set in a totem-pole or
pull configuration.
Because pull configuration is done through the Pin Configuration register, all intermediate PORT states during switching
of pin direction and pin values are avoided.
The I/O pin configurations are described further in this chapter, and summarized in Table 21-1.
21.6.4.1 Pin Configurations Summary
Table 21-1. Pin Configurations Summary
DIR
INEN
PULLEN
OUT
Configuration
0
0
0
X
Reset or analog I/O; all digital disabled
0
0
1
0
Pull-down; input disabled
0
0
1
1
Pull-up; input disabled
0
1
0
X
Input
0
1
1
0
Input with pull-down
0
1
1
1
Input with pull-up
1
0
X
X
Output; input disabled
1
1
X
X
Output; input enabled
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21.6.4.2 Input Configuration
Figure 21-4. I/O Configuration - Standard Input
PULLEN
PULLEN
INEN
DIR
0
1
0
PULLEN
INEN
DIR
1
1
0
DIR
OUT
IN
INEN
Figure 21-5. I/O Configuration - Input with Pull
PULLEN
DIR
OUT
IN
INEN
Note that when pull is enabled, the pull value is defined by the OUTx value.
21.6.4.3 Totem-Pole Output
When configured for totem-pole (push-pull) output, the pin is driven low or high according to the corresponding bit setting
in the OUT register. In this configuration, there is no current limitation for sink or source other than what the pin is capable
of. If the pin is configured for input, the pin will float if no external pull is connected. Note, that enabling the output driver
automatically disables pull.
Figure 21-6. I/O Configuration - Totem-Pole Output with Disabled Input
PULLEN
PULLEN
INEN
DIR
0
0
1
DIR
OUT
IN
INEN
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Figure 21-7. I/O Configuration - Totem-Pole Output with Enabled Input
PULLEN
PULLEN
INEN
DIR
0
1
1
PULLEN
INEN
DIR
1
0
0
DIR
OUT
IN
INEN
Figure 21-8. I/O Configuration - Output with Pull
PULLEN
DIR
OUT
IN
INEN
21.6.4.4 Digital Functionality Disabled
Figure 21-9. I/O Configuration - Reset or Analog I/O: Digital Output, Input and Pull Disabled
PULLEN
PULLEN
INEN
DIR
0
0
0
DIR
OUT
IN
INEN
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21.7
Register Summary
The I/O pins are organized in groups with up to 32 pins. Group 0 consists of the PA pins, group 1 the PB pins, etc. Each
group has its own set of registers. For example, the register address offset for the Data Direction (DIR) register for group
0 (PA00 to PA31) is 0x00, while the register address offset for the DIR register for group 1 (PB00 to PB31) is 0x80.
Bit
Offset
Name
Pos.
0x00
7:0
DIR[7:0]
0x01
15:8
DIR[15:8]
0x02
23:16
DIR[23:16]
0x03
31:24
DIR[31:24]
DIR
0x04
7:0
DIRCLR[7:0]
0x05
15:8
DIRCLR[15:8]
0x06
23:16
DIRCLR[23:16]
0x07
31:24
DIRCLR[31:24]
DIRCLR
0x08
7:0
DIRSET[7:0]
0x09
15:8
DIRSET[15:8]
0x0A
23:16
DIRSET[23:16]
0x0B
31:24
DIRSET[31:24]
DIRSET
0x0C
7:0
DIRTGL[7:0]
0x0D
15:8
DIRTGL[15:8]
0x0E
23:16
DIRTGL[23:16]
0x0F
31:24
DIRTGL[31:24]
DIRTGL
0x10
7:0
OUT[7:0]
0x11
15:8
OUT[15:8]
0x12
23:16
OUT[23:16]
0x13
31:24
OUT[31:24]
OUT
0x14
7:0
OUTCLR[7:0]
0x15
15:8
OUTCLR[15:8]
0x16
23:16
OUTCLR[23:16]
0x17
31:24
OUTCLR[31:24]
0x18
7:0
OUTSET[7:0]
OUTCLR
15:8
OUTSET[15:8]
0x1A
0x19
23:16
OUTSET[23:16]
0x1B
31:24
OUTSET[31:24]
0x1C
7:0
OUTTGL[7:0]
OUTSET
0x1D
15:8
OUTTGL[15:8]
0x1E
23:16
OUTTGL[23:16]
0x1F
31:24
OUTTGL[31:24]
0x20
7:0
IN[7:0]
OUTTGL
0x21
15:8
IN[15:8]
0x22
23:16
IN[23:16]
0x23
31:24
IN[31:24]
0x24
7:0
SAMPLING[7:0]
IN
0x25
15:8
SAMPLING[15:8]
0x26
23:16
SAMPLING[23:16]
0x27
31:24
SAMPLING[31:24]
CTRL
Atmel | SMART SAM D20 [DATASHEET]
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295
Bit
Offset
Name
0x28
Pos.
7:0
0x29
PINMASK[7:0]
15:8
PINMASK[15:8]
WRCONFIG
0x2A
23:16
0x2B
31:24
DRVSTR
HWSEL
WRPINCFG
PULLEN
WRPMUX
INEN
PMUXEN
PMUX[3:0]
0x2C
0x2D
Reserved
0x2E
0x2F
0x30
PMUX0
7:0
PMUXO[3:0]
PMUXE[3:0]
0x31
PMUX1
7:0
PMUXO[3:0]
PMUXE[3:0]
…
…
…
0x3E
PMUX14
7:0
PMUXO[3:0]
PMUXE[3:0]
0x3F
PMUX15
7:0
PMUXO[3:0]
PMUXE[3:0]
0x40
PINCFG0
7:0
DRVSTR
PULLEN
INEN
PMUXEN
0x41
PINCFG1
7:0
DRVSTR
PULLEN
INEN
PMUXEN
…
…
…
0x5E
PINCFG30
7:0
DRVSTR
PULLEN
INEN
PMUXEN
0x5F
PINCFG31
7:0
DRVSTR
PULLEN
INEN
PMUXEN
Atmel | SMART SAM D20 [DATASHEET]
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296
21.8
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-Protected property in each individual register description. Refer to “Register Access Protection” on page 289
for details.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
297
21.8.1 Data Direction
Name:
DIR
Offset:
0x00+x*0x80 [x=0..1]
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
DIR[31:24]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
DIR[23:16]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
DIR[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DIR[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31:0 – DIR[31:0]: Port Data Direction
These bits set the data direction for the individual I/O pins in the PORT group.
0: The corresponding I/O pin in the group is configured as an input.
1: The corresponding I/O pin in the group is configured as an output.
Atmel | SMART SAM D20 [DATASHEET]
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298
21.8.2 Data Direction Clear
This register allows the user to set one or more I/O pins as an input, without doing a read-modify-write operation.
Changes in this register will also be reflected in the Data Direction (DIR), Data Direction Toggle (DIRTGL) and Data
Direction Set (DIRSET) registers.
Name:
DIRCLR
Offset:
0x04+x*0x80 [x=0..1]
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
DIRCLR[31:24]
Access
Reset
Bit
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
23
22
21
20
19
18
17
16
DIRCLR[23:16]
Access
Reset
Bit
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
DIRCLR[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DIRCLR[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31:0 – DIRCLR[31:0]: Port Data Direction Clear
0: The I/O pin direction is cleared.
1: The I/O pin direction is set.
Writing a zero to a bit has no effect.
Writing a one to a bit will clear the corresponding bit in the DIR register, which configures the I/O pin as an input.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
299
21.8.3 Data Direction Set
This register allows the user to set one or more I/O pins as an output, without doing a read-modify-write operation.
Changes in this register will also be reflected in the Data Direction (DIR), Data Direction Toggle (DIRTGL) and Data
Direction Clear (DIRCLR) registers.
Name:
DIRSET
Offset:
0x08+x*0x80 [x=0..1]
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
DIRSET[31:24]
Access
Reset
Bit
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
23
22
21
20
19
18
17
16
DIRSET[23:16]
Access
Reset
Bit
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
DIRSET[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DIRSET[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31:0 – DIRSET[31:0]: Port Data Direction Set
0: The I/O pin direction is cleared.
1: The I/O pin direction is set.
Writing a zero to a bit has no effect.
Writing a one to a bit will set the corresponding bit in the DIR register, which configures the I/O pin as an output.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
300
21.8.4 Data Direction Toggle
This register allows the user to toggle the direction of one or more I/O pins, without doing a read-modify-write operation.
Changes in this register will also be reflected in the Data Direction (DIR), Data Direction Set (DIRSET) and Data Direction
Clear (DIRCLR) registers.
Name:
DIRTGL
Offset:
0x0C+x*0x80 [x=0..1]
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
DIRTGL[31:24]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
DIRTGL[23:16]
Access
Reset
Bit
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
DIRTGL[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DIRTGL[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31:0 – DIRTGL[31:0]: Port Data Direction Toggle
0: The I/O pin direction is cleared.
1: The I/O pin direction is set.
Writing a zero to a bit has no effect.
Writing a one to a bit will toggle the corresponding bit in the DIR register, which reverses the direction of the I/O
pin.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
301
21.8.5 Data Output Value
This register sets the data output drive value for the individual I/O pins in the PORT.
Name:
OUT
Offset:
0x10+x*0x80 [x=0..1]
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
OUT[31:24]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
OUT[23:16]
Access
Reset
Bit
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
OUT[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
OUT[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31:0 – OUT[31:0]: Port Data Output Value
These bits set the logical output drive level of I/O pins configured as outputs via the Data Direction register (DIR).
For pins configured as inputs via the Data Direction register (DIR) with pull enabled via the Pull Enable register
(PULLEN), these bits will set the input pull direction.
0: The I/O pin output is driven low, or the input is connected to an internal pull-down.
1: The I/O pin output is driven high, or the input is connected to an internal pull-up.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
302
21.8.6 Data Output Value Clear
This register allows the user to set one or more output I/O pin drive levels low, without doing a read-modify-write
operation. Changes in this register will also be reflected in the Data Output Value (OUT), Data Output Value Toggle
(OUTTGL) and Data Output Value Set (OUTSET) registers.
Name:
OUTCLR
Offset:
0x14+x*0x80 [x=0..1]
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
OUTCLR[31:24]
Access
Reset
Bit
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
23
22
21
20
19
18
17
16
OUTCLR[23:16]
Access
Reset
Bit
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
OUTCLR[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
OUTCLR[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31:0 – OUTCLR[31:0]: Port Data Output Value Clear
0: The I/O pin output is driven low.
1: The I/O pin output is driven high.
Writing a zero to a bit has no effect.
Writing a one to a bit will clear the corresponding bit in the OUT register, which sets the output drive level low for
I/O pins configured as outputs via the Data Direction register (DIR). For pins configured as inputs via the Data
Direction register (DIR) with pull enabled via the Pull Enable register (PULLEN), these bits will set the input pull
direction to an internal pull-down.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
303
21.8.7 Data Output Value Set
This register allows the user to set one or more output I/O pin drive levels high, without doing a read-modify-write
operation. Changes in this register will also be reflected in the Data Output Value (OUT), Data Output Value Toggle
(OUTTGL) and Data Output Value Clear (OUTCLR) registers.
Name:
OUTSET
Offset:
0x18+x*0x80 [x=0..1]
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
OUTSET[31:24]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
OUTSET[23:16]
Access
Reset
Bit
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
OUTSET[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
OUTSET[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31:0 – OUTSET[31:0]: Port Data Output Value Set
0: The I/O pin output is driven low.
1: The I/O pin output is driven high.
Writing a zero to a bit has no effect.
Writing a one to a bit will set the corresponding bit in the OUT register, which sets the output drive level high for I/O
pins configured as outputs via the Data Direction register (DIR). For pins configured as inputs via the Data Direction register (DIR) with pull enabled via the Pull Enable register (PULLEN), these bits will set the input pull direction
to an internal pull-up.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
304
21.8.8 Data Output Value Toggle
This register allows the user to toggle the drive level of one or more output I/O pins, without doing a read-modify-write
operation. Changes in this register will also be reflected in the Data Output Value (OUT), Data Output Value Set
(OUTSET) and Data Output Value Clear (OUTCLR) registers.
Name:
OUTTGL
Offset:
0x1C+x*0x80 [x=0..1]
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
OUTTGL[31:24]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
OUTTGL[23:16]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
OUTTGL[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
OUTTGL[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31:0 – OUTTGL[31:0]: Port Data Output Value Toggle
0: The I/O pin output is driven low.
1: The I/O pin output is driven high.
Writing a zero to a bit has no effect.
Writing a one to a bit will toggle the corresponding bit in the OUT register, which inverts the output drive level for
I/O pins configured as outputs via the Data Direction register (DIR). For pins configured as inputs via the Data
Direction register (DIR) with pull enabled via the Pull Enable register (PULLEN), these bits will toggle the input pull
direction.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
305
21.8.9 Data Input Value
Name:
IN
Offset:
0x20+x*0x80 [x=0..1]
Reset:
0x00000000
Property:
-
Bit
31
30
29
28
27
26
25
24
IN[31:24]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
IN[23:16]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
Bit
IN[15:8]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
IN[7:0]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bits 31:0 – IN[31:0]: Port Data Input Value
These bits are cleared when the corresponding I/O pin input sampler detects a logical low level on the input pin.
These bits are set when the corresponding I/O pin input sampler detects a logical high level on the input pin.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
306
21.8.10 Control
Name:
CTRL
Offset:
0x24+x*0x80 [x=0..1]
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
SAMPLING[31:24]
Access
Reset
Bit
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
23
22
21
20
19
18
17
16
SAMPLING[23:16]
Access
Reset
Bit
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
SAMPLING[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
SAMPLING[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31:0 – SAMPLING[31:0]: Input Sampling Mode
Configures the input sampling functionality of the I/O pin input samplers for pins configured as inputs via the Data
Direction register (DIR).
0: The I/O pin input synchronizer is disabled.
1: The I/O pin input synchronizer is enabled.
The input samplers are enabled and disabled in sub-groups of eight. Thus, if any pins within a byte request continuous sampling, all pins in that eight pin sub-group will be continuously sampled.
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129N–SAM-D20_datasheet–01/2015
307
21.8.11 Write Configuration
This write-only register is used to configure several pins simultaneously with the same configuration and/or peripheral
multiplexing.
In order to avoid the side effect of non-atomic access, 8-bit or 16-bit writes to this register will have no effect. Reading this
register always returns zero.
Name:
WRCONFIG
Offset:
0x28+x*0x80 [x=0..1]
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
HWSEL
WRPINCFG
Access
W
W
R
W
W
Reset
0
0
0
0
Bit
23
22
21
20
26
25
24
W
W
W
0
0
0
0
19
18
17
16
PULLEN
INEN
PMUXEN
WRPMUX
PMUX[3:0]
DRVSTR
Access
R
W
R
W
W
W
W
W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
PINMASK[15:8]
Access
W
W
W
W
W
W
W
W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
PINMASK[7:0]
Access
W
W
W
W
W
W
W
W
Reset
0
0
0
0
0
0
0
0
z
Bit 31 – HWSEL: Half-Word Select
This bit selects the half-word field of a 32-pin group to be reconfigured in the atomic write operation.
0: The lower 16 pins of the PORT group will be configured.
1: The upper 16 pins of the PORT group will be configured.
This bit will always read as zero.
z
Bit 30 – WRPINCFG: Write PINCFG
This bit determines whether the atomic write operation will update the Pin Configuration register (PINCFGy) or not
for all pins selected by the WRCONFIG.PINMASK and WRCONFIG.HWSEL bits.
0: The PINCFGy registers of the selected pins will not be updated.
1: The PINCFGy registers of the selected pins will be updated.
Writing a zero to this bit has no effect.
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Writing a one to this bit updates the configuration of the selected pins with the written WRCONFIG.DRVSTR,
WRCONFIG.SLEWLIM, WRCONFIG.ODRAIN, WRCONFIG.PULLEN, WRCONFIG.INEN, WRCONFIG.PMUXEN
and WRCONFIG.PINMASK values.
This bit will always read as zero.
z
Bit 29 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 28 – WRPMUX: Write PMUX
This bit determines whether the atomic write operation will update the Peripheral Multiplexing register (PMUXn) or
not for all pins selected by the WRCONFIG.PINMASK and WRCONFIG.HWSEL bits.
0: The PMUXn registers of the selected pins will not be updated.
1: The PMUXn registers of the selected pins will be updated.
Writing a zero to this bit has no effect.
Writing a one to this bit updates the pin multiplexer configuration of the selected pins with the written WRCONFIG.PMUX value.
This bit will always read as zero.
z
Bits 27:24 – PMUX[3:0]: Peripheral Multiplexing
These bits determine the new value written to the Peripheral Multiplexing register (PMUXn) for all pins selected by
the WRCONFIG.PINMASK and WRCONFIG.HWSEL bits, when the WRCONFIG.WRPMUX bit is set.
These bits will always read as zero.
z
Bit 23 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 22 – DRVSTR: Output Driver Strength Selection
This bit determines the new value written to PINCFGy.DRVSTR for all pins selected by the WRCONFIG.PINMASK
and WRCONFIG.HWSEL bits the WRCONFIG.WRPINCFG bit is set.
This bit will always read as zero.
z
Bit 21:19 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 18 – PULLEN: Pull Enable
This bit determines the new value written to PINCFGy.PULLEN for all pins selected by the WRCONFIG.PINMASK
and WRCONFIG.HWSEL bits when the WRCONFIG.WRPINCFG bit is set.
This bit will always read as zero.
z
Bit 17 – INEN: Input Enable
This bit determines the new value written to PINCFGy.DRVSTR for all pins selected by the WRCONFIG.PINMASK
and WRCONFIG.HWSEL bits when the WRCONFIG.WRPINCFG bit is set.
This bit will always read as zero.
z
Bit 16 – PMUXEN: Peripheral Multiplexer Enable
This bit determines the new value written to PINCFGy.PMUXEN for all pins selected by the WRCONFIG.PINMASK and WRCONFIG.HWSEL bits when the WRCONFIG.WRPINCFG bit is set.
This bit will always read as zero.
z
Bits 15:0 – PINMASK[15:0]: Pin Mask for Multiple Pin Configuration
These bits select the pins to be configured within the half-word group selected by the WRCONFIG.HWSEL bit.
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0: The configuration of the corresponding I/O pin in the half-word group will be left unchanged.
1: The configuration of the corresponding I/O pin in the half-word pin group will be updated.
These bits will always read as zero.
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21.8.12 Peripheral Multiplexing n
There are up to 16 Peripheral Multiplexing registers in each group, one for every set of two subsequent I/O lines. The n
denotes the number of the set of I/O lines, while the m denotes the number of the group.
Name:
PMUXn
Offset:
0x30+n*0x1+x*0x80 [n=0..15] (x=0..1)
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
PMUXO[3:0]
Access
0
PMUXE[3:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Reset
z
1
Bits 7:4 – PMUXO[3:0]: Peripheral Multiplexing Odd
These bits select the peripheral function for odd-numbered pins (2*n + 1) of a PORT group, if the corresponding
PINCFGy.PMUXEN bit is one.
Not all possible values for this selection may be valid. For more details, refer to “I/O Multiplexing and Considerations” on page 16.
z
Bits 3:0 – PMUXE[3:0]: Peripheral Multiplexing Even
These bits select the peripheral function for even-numbered pins (2*n) of a PORT group, if the corresponding
PINCFGy.PMUXEN bit is one.
Not all possible values for this selection may be valid. For more details, refer to “I/O Multiplexing and Considerations” on page 16.
Value
Name
Description
0x0
A
Peripheral function A selected
0x1
B
Peripheral function B selected
0x2
C
Peripheral function C selected
0x3
D
Peripheral function D selected
0x4
E
Peripheral function E selected
0x5
F
Peripheral function F selected
0x6
G
Peripheral function G selected
0x7
H
Peripheral function H selected
0x8-0xF
Reserved
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21.8.13 Pin Configuration y
There are up to 32 Pin Configuration registers in each group, one for each I/O line. The y denotes the number of the I/O
line, while the x denotes the number of the group.
Name:
PINCFGy
Offset:
0x40+y*0x1+x*0x80 [n=0..31] (x=0..1)
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
DRVSTR
2
1
0
PULLEN
INEN
PMUXEN
Access
R
R/W
R
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bit 7 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 6 – DRVSTR: Output Driver Strength Selection
This bit controls the output driver strength of an I/O pin configured as an output.
0: Pin drive strength is set to normal drive strength.
1: Pin drive strength is set to stronger drive strength.
z
Bits 5:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – PULLEN: Pull Enable
This bit enables the internal pull-up or pull-down resistor of an I/O pin configured as an input.
0: Internal pull resistor is disabled, and the input is in a high-impedance configuration.
1: Internal pull resistor is enabled, and the input is driven to a defined logic level in the absence of external input.
z
Bit 1 – INEN: Input Enable
This bit controls the input buffer of an I/O pin configured as either an input or output.
0: Input buffer for the I/O pin is disabled, and the input value will not be sampled.
1: Input buffer for the I/O pin is enabled, and the input value will be sampled when required.
Writing a zero to this bit disables the input buffer completely, preventing read-back of the physical pin state when
the pin is configured as either an input or output.
z
Bit 0 – PMUXEN: Peripheral Multiplexer Enable
This bit enables or disables the peripheral multiplexer selection set in the Peripheral Multiplexing register (PMUXn)
to enable or disable alternative peripheral control over an I/O pin direction and output drive value.
0: The peripheral multiplexer selection is disabled, and the PORT registers control the direction and output drive
value.
1: The peripheral multiplexer selection is enabled, and the selected peripheral controls the direction and output
drive value.
Writing a zero to this bit allows the PORT to control the pad direction via the Data Direction register (DIR) and output drive value via the Data Output Value register (OUT). The peripheral multiplexer value in PMUXn is ignored.
Writing a one to this bit enables the peripheral selection in PMUXn to control the pad. In this configuration, the
physical pin state may still be read from the Data Input Value register (IN) if PINCFGy.INEN is set.
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22.
EVSYS – Event System
22.1
Overview
The Event System (EVSYS) allows autonomous, low-latency and configurable communication between peripherals.
Several peripherals can be configured to emit and/or respond to signals known as events. The exact condition to
generate an event, or the action taken upon receiving an event, is specific to each module. Peripherals that respond to
events are called event users. Peripherals that emit events are called event generators. A peripheral can have one or
more event generators and can have one or more event users.
Communication is made without CPU intervention and without consuming system resources such as bus or RAM
bandwidth. This reduces the load on the CPU and other system resources, compared to a traditional interrupt-based
system.
22.2
Features
z System for direct peripheral-to-peripheral communication and signaling
z 8 configurable event channels, where each channel can:
z
z
Be connected to any event generator
Provide a pure asynchronous, resynchronized or synchronous path
z 59 event generators
z 14 event users
z Configurable edge detector
z Peripherals can be event generators, event users or both
z SleepWalking and interrupt for operation in low-power modes
z Software event generation
z Each event user can choose which channel to listen to
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22.3
Block Diagram
Figure 22-1. Event System Block Diagram
EVSYS
USER
MUX
CHANNELS
PERIPHERALS
GENERATOR
EVENTS
PERIPHERALS
USERS EVENTS
CLOCK REQUESTS
GCLK
22.4
Signal Description
Not applicable.
22.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
22.5.1
I/O Lines
Not applicable.
22.5.2 Power Management
The EVSYS can be used to wake up the CPU from all sleep modes, even if the clock used by the EVSYS channel and
the EVSYS bus clock are disabled. Refer to “PM – Power Manager” on page 107 for details on the different sleep modes.
In all power save modes where the clock for the EVSYS is stopped, the device can wake up the EVSYS clock.
Some event generators can generate an event when the system clock is stopped. The generic clock (GCLK_EVSYS_x)
for this channel will be restarted if the channel uses a synchronized path or a resynchronized path, without waking the
system from sleep. The clock remains active only as long as necessary to handle the event. After the event has been
handled, the clock will be turned off and the system will remain in the original sleep mode. This is known as
SleepWalking. When an asynchronous path is used, there is no need for the clock to be activated for the event to be
propagated to the user.
On a software reset, all registers are set to their reset values and any ongoing events are canceled.
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22.5.3 Clocks
The EVSYS bus clock (CLK_EVSYS_APB) can be enabled and disabled in the Power Manager, and the default state of
CLK_EVSYS_APB can be found in the Peripheral Clock Masking section in “PM – Power Manager” on page 107.
Each EVSYS channel has a dedicated generic clock (GCLK_EVSYS_x). These are used for detection and propagation
of events for each channel. These clocks must be configured and enabled in the generic clock controller before using the
EVSYS. Refer to “Enabling a Generic Clock” on page 89 for details.
22.5.4 DMA
Not applicable.
22.5.5 Interrupts
The interrupt request line is connected to the interrupt controller. Using the EVSYS interrupts requires the interrupt
controller to be configured first. Refer to “Nested Vector Interrupt Controller” on page 30 for details.
22.5.6 Events
Not applicable.
22.5.7 Debug Operation
When the CPU is halted in debug mode, the EVSYS continues normal operation. If the EVSYS is configured in a way
that requires it to be periodically serviced by the CPU through interrupts or similar, improper operation or data loss may
result during debugging.
22.5.8 Register Access Protection
All registers with write-access are optionally write-protected by the Peripheral Access Controller (PAC), except the
following register:
z
Interrupt Flag Status and Clear register (INTFLAG)
Write-protection is denoted by the Write-Protected property in the register description.
Write-protection does not apply for accesses through an external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
22.5.9 Analog Connections
Not applicable.
22.6
Functional Description
22.6.1 Principle of Operation
Event users are connected to multiplexers that have all available event channels as input. The multiplexer must be
configured to select one of these channels. The channels can be configured to route signals from any event generator,
but cannot be connected to multiple event generators.
22.6.2 Basic Operation
22.6.2.1 Initialization
The peripheral that is to act as event generator should be configured to be able to generate events. The peripheral to act
as event user should be configured to handle incoming events.
When this has been done, the event system is ready to be configured. The configuration must follow this order:
1.
Configure the event user by performing a single 16-bit write to the User Multiplexer register (USER) with:
6.1.
The channel to be connected to a user is written to the Channel bit group (USER.CHANNEL)
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1.1. The user to connect the channel is written to the User bit group (USER.USER)
2.
Configure the channel by performing a single 32-bit write to the Channel (CHANNEL) register with:
The channel to be configured is written to the Channel Selection bit group
(CHANNEL.CHANNEL)
2.1. The path to be used is written to the Path Selection bit group (CHANNEL.PATH)
2.2. The type of edge detection to use on the channel is written to the Edge Selection bit group
(CHANNEL.EDGSEL)
2.3. The event generator to be used is written to the Event Generator bit group (CHANNEL.EVGEN)
6.2.
22.6.2.2 Enabling, Disabling and Resetting
The EVSYS is always enabled.
The EVSYS is reset by writing a one to the Software Reset bit in the Control register (CTRL.SWRST). All registers in the
EVSYS will be reset to their initial state. Refer to the CTRL register for details.
22.6.2.3 User Multiplexer Setup
Each user multiplexer is dedicated to one event user. A user multiplexer receives all event channel outputs and must be
configured to select one of these channels. The user must always be configured before the channel is configured. A full
list of selectable users can be found in the User Multiplexer register (USER) description. Refer to Table 22-6 for details.
To configure a user multiplexer, the USER register must be written in a single 16-bit write.
It is possible to read out the configuration of a user by first selecting the user by writing to USER.USER using an 8-bit
write and then performing a read of the USER register.
Figure 22-2. User MUX
CHANNEL_EVT_0
CHANNEL_EVT_1
CHANNEL_EVT_m
USER
MUX
USER.CHANNEL
USER_EVT_x
USER_EVT_y
PERIPHERAL A
USER_EVT_z
PERIPHERAL B
22.6.2.4 Channel Setup
The channel to be used with an event user must be configured with an event generator. The path of the channel should
be configured, and when using a synchronous path or resynchronized path, the edge selection should be configured. All
these configurations are available in the Channel register (CHANNEL).
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To configure a channel, the Channel register must be written in a single 32-bit write.
It is possible to read out the configuration of a channel by first selecting the channel by writing to CHANNEL.CHANNEL
using a, 8-bit write, and then performing a read of the CHANNEL register.
Event Generators
The event generator is selected by writing to the Event Generator bit group in the Channel register (CHANNEL.EVGEN).
A full list of selectable generators can be found in the CHANNEL register description. Refer to Table 22-3 for details.
The channels are not connected to any of the event generators (CHANNEL.EVGEN = 0x00) by default.
22.6.2.5 Channel Path
There are three different ways to propagate the event provided by an event generator:
z
Asynchronous path
z
Synchronous path
z
Resynchronized path
Figure 22-3. Channel
CLOCK_REQUEST_m
CHANNEL m
SLEEPWALKING
DETECTOR
ASYNC
GENERATORS EVENTS
SYNC
CHANNEL_EVT_m
EDGE
DETECTION
PERIPHERALS
RESYNC
CHANNEL.SWEVT
CHANNEL.EDGSEL
CHANNEL.PATH
CHANNEL.EVGEN
The path is selected by writing to the Path Selection bit group in the Channel register (CHANNEL.PATH).
Asynchronous Path
When using the asynchronous path, the events are propagated from the event generator to the event user with no
intervention from the event system. This means that if the GCLK_EVSYS_x for the channel used is inactive, the event
will still be propagated to the user.
Events propagated in the asynchronous path cannot generate any interrupts, and no channel status bits will indicate the
state of the channel. No edge detection is available; this must be handled in the event user.
When the event generator and the event user share the same generic clock, using the asynchronous path will propagate
the event with the least amount of latency.
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Synchronous Path
The synchronous path should be used when the event generator and the event channel share the same generic clock. If
they do not share the same clock, a logic change from the event generator to the event channel might not be detected in
the channel, which means that the event will not be propagated to the event user.
When using the synchronous path, the channel is capable of generating interrupts. The channel status bits in the
Channel Status register (CHSTATUS) are also updated and available for use.
If the Generic Clocks Request bit in the Control register (CTRL.GCLKREQ) is zero, the channel operates in
SleepWalking mode and request the configured generic clock only when an event is to be propagated through the
channel. If CTRL.GCLKREQ is one, the generic clock will always be on for the configured channel.
Resynchronized Path
The resynchronized path should be used when the event generator and the event channel do not share the same clock.
When the resynchronized path is used, resynchronization of the event from the event generator is done in the channel.
When the resynchronized path is used, the channel is capable of generating interrupts. The channel status bits in the
Channel Status register (CHSTATUS) are also updated and available for use.
If the Generic Clocks Request bit in the Control register (CTRL.GCLKREQ) is zero, the channel operates in
SleepWalking mode and request the configured generic clock only when an event is to be propagated through the
channel. If CTRL.GCLKREQ is one, the generic clock will always be on for the configured channel.
22.6.2.6 Edge Detection
When synchronous or resynchronized paths are used, edge detection must be used. The event system can perform
edge detection in three different ways:
z
Generate an event only on the rising edge
z
Generate an event only on the falling edge
z
Generate an event on rising and falling edges.
Edge detection is selected by writing to the Edge Selection bit group in the Channel register (CHANNEL.EDGSEL).
If the generator event is a pulse, the Both Edges method must not be selected. Use the Rising Edge or Falling Edge
detection method, depending on the generator event default level.
22.6.2.7 Channel Status
The Channel Status register (CHSTATUS) updates the status of the channels when a synchronous or resynchronized
path is in use. There are two different status bits in CHSTATUS for each of the available channels: The
CHSTATUS.CHBUSYx bit is set to one if an event on the corresponding channel x has not been handled by all event
users connected to that channel.
The CHSTATUS.USRRDYx bit is set to one if all event users connected to the corresponding channel x are ready to
handle incoming events on that channel.
22.6.2.8 Software Event
A software event can be initiated on a channel by writing a one to the Software Event bit in the Channel register
(CHANNEL.SWEVT) together with the Channel bits (CHANNEL.CHANNEL). This will generate a software event on the
selected channel.
The software event can be used for application debugging, and functions like any event generator. To use the software
event, the event path must be configured to either a synchronous path or resynchronized path (CHANNEL.PATH = 0x0
or 0x1), edge detection must be configured to rising-edge detection (CHANNEL.EDGSEL= 0x1) and the Generic Clock
Request bit must be set to one (CTRL.GCLKREQ=0x1).
22.6.3 Interrupts
The EVSYS has the following interrupt sources:
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z
Overrun Channel x (OVRx): this is an asynchronous interrupt and can be used to wake-up the device from any
sleep mode. (INTFLAG.OVRx)
z
Event Detected Channel x (EVDx): this is an asynchronous interrupt and can be used to wake-up the device from
any sleep mode. (INTFLAG)
Each interrupt source has an interrupt flag associated with it. The interrupt flag in the Interrupt Flag Status and Clear
register (INTFLAG) is set when the interrupt condition occurs. Each interrupt can be individually enabled by writing a one
to the corresponding bit in the Interrupt Enable Set register (INTENSET), and disabled by writing a one to the
corresponding bit in the Interrupt Enable Clear register (INTENCLR). An interrupt request is generated when the interrupt
flag is set and the corresponding interrupt is enabled. The interrupt request remains active until the interrupt flag is
cleared, the interrupt is disabled or the EVSYS is reset.
See the INTFLAG register for details on how to clear interrupt flags. The EVSYS has one common interrupt request line
for all the interrupt sources. The user must read the INTFLAG register to determine which interrupt condition is present.
Note that interrupts must be globally enabled for interrupt requests to be generated.
Refer to “Nested Vector Interrupt Controller” on page 30 for details.
22.6.3.1 The Overrun Channel x Interrupt
The Overrun Channel x interrupt flag in the Interrupt Flag Status and Clear register (INTFLAG.OVRx) is set and the
optional interrupt is generated in the following two cases:
z
At least one of the event users on channel x is not ready when a new event occurs
z
An event occurs when the previous event on channel x has not yet been handled by all event users
INTFLAG.OVRx will be set when using a synchronous or resynchronized path, but not when using an asynchronous
path.
22.6.3.2 The Event Detected Channel x Interrupt
The Event Detected Channel x interrupt flag in the Interrupt Flag Status and Clear register (INTFLAG.EVDx) is set when
an event coming from the event generator configured on channel x is detected.
INTFLAG.EVDx will be set when using a synchronous and resynchronized path, but not when using an asynchronous
path.
22.6.4 Sleep Mode Operation
The EVSYS can generate interrupts to wake up the device from any sleep mode.
Some event generators can generate an event when the system clock is stopped. The generic clock
(GCLK_EVSYS_CHANNELx) for this channel will be restarted if the channel uses a synchronized path or a
resynchronized path, without waking the system from sleep. The clock remains active only as long as necessary to
handle the event. After the event has been handled, the clock will be turned off and the system will remain in the original
sleep mode. This is known as SleepWalking. When an asynchronous path is used, there is no need for the clock to be
activated for the event to be propagated to the user.
On a software reset, all registers are set to their reset values and any ongoing events are canceled
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22.7
Register Summary
Offset
Name
Bit Pos.
0x00
CTRL
7:0
0x01
Reserved
0x02
Reserved
0x03
Reserved
0x04
GCLKREQ
7:0
0x05
SWRST
CHANNEL[7:0]
15:8
SWEVT
CHANNEL
0x06
23:16
0x07
31:24
0x08
EVGEN[7:0]
EDGSEL[1:0]
7:0
USER[7:0]
15:8
CHANNEL[7:0]
PATH[1:0]
USER
0x09
0x0A
Reserved
0x0B
Reserved
0x0C
0x0D
7:0
USRRDY7
USRRDY6
USRRDY5
USRRDY4
USRRDY3
USRRDY2
USRRDY1
USRRDY0
15:8
CHBUSY7
CHBUSY6
CHBUSY5
CHBUSY4
CHBUSY3
CHBUSY2
CHBUSY1
CHBUSY0
CHSTATUS
0x0E
23:16
0x0F
31:24
0x10
7:0
OVR7
OVR6
OVR5
OVR4
OVR3
OVR2
OVR1
OVR0
15:8
EVD7
EVD6
EVD5
EVD4
EVD3
EVD2
EVD1
EVD0
0x11
INTENCLR
0x12
23:16
0x13
31:24
0x14
7:0
OVR7
OVR6
OVR5
OVR4
OVR3
OVR2
OVR1
OVR0
15:8
EVD7
EVD6
EVD5
EVD4
EVD3
EVD2
EVD1
EVD0
0x15
INTENSET
0x16
23:16
0x17
31:24
0x18
7:0
OVR7
OVR6
OVR5
OVR4
OVR3
OVR2
OVR1
OVR0
15:8
EVD7
EVD6
EVD5
EVD4
EVD3
EVD2
EVD1
EVD0
0x19
INTFLAG
0x1A
23:16
0x1B
31:24
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22.8
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-Protected property in each individual register description. Refer to “Register Access Protection” on page 315
and “PAC – Peripheral Access Controller” on page 34 for details.
22.8.1 Control
Name:
CTRL
Offset:
0x00
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
GCLKREQ
0
SWRST
Access
R
R
R
R/W
R
R
R
W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 4 – GCLKREQ: Generic Clock Requests
This bit is used to determine whether the generic clocks used for the different channels should be on all the time or
only when an event needs the generic clock. Events propagated through asynchronous paths will not need a
generic clock.
0: Generic clock is requested and turned on only if an event is detected.
1: Generic clock for a channel is always on.
z
Bits 3:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – SWRST: Software Reset
Writing a zero to this bit has no effect.
Writing a one to this bit resets all registers in the EVSYS to their initial state.
Writing a one to CTRL.SWRST will always take precedence, meaning that all other writes in the same write-operation will be discarded.
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22.8.2 Channel
This register allows the user to configure the channel specified in the CHANNEL bit group. To write to this register, do a
single 32-bit write of all the configuration and channel selection data.
To read from this register, first do an 8-bit write to the CHANNEL.CHANNEL bit group specifying the channel
configuration to be read, and then read the Channel register (CHANNEL).
Name:
CHANNEL
Offset:
0x04
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
EDGSEL[1:0]
24
PATH[1:0]
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
23
22
21
20
19
18
17
16
Bit
EVGEN[7:0]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
SWEVT
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
CHANNEL[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 31:28 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 27:26 – EDGSEL[1:0]: Edge Detection Selection
These bits set the type of edge detection to be used on the channel.
These bits must be written to zero when using the asynchronous path.
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Table 22-1. Edge Detection Selection
Value
Name
Description
0x0
NO_EVT_OUTPUT
No event output when using the resynchronized or synchronous path
0x1
RISING_EDGE
Event detection only on the rising edge of the signal from the event generator
0x2
FALLING_EDGE
Event detection only on the falling edge of the signal from the event generator
0x3
BOTH_EDGES
Event detection on rising and falling edges of the signal from the event
generator
z
Bits 25:24 – PATH[1:0]: Path Selection
These bits are used to choose the path to be used by the selected channel.
The path choice can be limited by the channel source, see Table 22-6.
Table 22-2. Path Selection
Value
Name
Description
0x0
SYNCHRONOUS
Synchronous path
0x1
RESYNCHRONIZED
Resynchronized path
0x2
ASYNCHRONOUS
Asynchronous path
0x3
-
Reserved
z
Bits 23:16 – EVGEN[7:0]: Event Generator
These bits are used to choose the event generator to connect to the selected channel.
Table 22-3. Event Generator Selection
Value
Event Generator
Description
0x00
NONE
No event generator selected
0x01
RTC CMP0
Compare 0 (mode 0 and 1) or Alarm 0 (mode 2)
0x02
RTC CMP1
Compare 1
0x03
RTC OVF
Overflow
0x04
RTC PER0
Period 0
0x05
RTC PER1
Period 1
0x06
RTC PER2
Period 2
0x07
RTC PER3
Period 3
0x08
RTC PER4
Period 4
0x09
RTC PER5
Period 5
0x0A
RTC PER6
Period 6
0x0B
RTC PER7
Period 7
0x0C
EIC EXTINT0
External Interrupt 0
0x0D
EIC EXTINT1
External Interrupt 1
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Table 22-3. Event Generator Selection (Continued)
Value
Event Generator
Description
0x0E
EIC EXTINT2
External Interrupt 2
0x0F
EIC EXTINT3
External Interrupt 3
0x10
EIC EXTINT4
External Interrupt 4
0x11
EIC EXTINT5
External Interrupt 5
0x12
EIC EXTINT6
External Interrupt 6
0x13
EIC EXTINT7
External Interrupt 7
0x14
EIC EXTINT8
External Interrupt 8
0x15
EIC EXTINT9
External Interrupt 9
0x16
EIC EXTINT10
External Interrupt 10
0x17
EIC EXTINT11
External Interrupt 11
0x18
EIC EXTINT12
External Interrupt 12
0x19
EIC EXTINT13
External Interrupt 13
0x1A
EIC EXTINT14
External Interrupt 14
0x1B
EIC EXTINT15
External Interrupt 15
0x1C
TC0 OVF
Overflow/Underflow
0x1D
TC0 MC0
Match/Capture 0
0x1E
TC0 MC1
Match/Capture 1
0x1F
TC1 OVF
Overflow/Underflow
0x20
TC1 MC0
Match/Capture 0
0x21
TC1 MC1
Match/Capture 1
0x22
TC2 OVF
Overflow/Underflow
0x23
TC2 MC0
Match/Capture 0
0x24
TC2 MC1
Match/Capture 1
0x25
TC3 OVF
Overflow/Underflow
0x26
TC3 MC0
Match/Capture 0
0x27
TC3 MC1
Match/Capture 1
0x28
TC4 OVF
Overflow/Underflow
0x29
TC4 MC0
Match/Capture 0
0x2A
TC4 MC1
Match/Capture 1
0x2B
TC5 OVF
Overflow/Underflow
0x2C
TC5 MC0
Match/Capture 0
0x2D
TC5 MC1
Match/Capture 1
0x2E
TC6 OVF
Overflow/Underflow
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Table 22-3. Event Generator Selection (Continued)
Value
Event Generator
Description
0x2F
TC6 MC0
Match/Capture 0
0x30
TC6 MC1
Match/Capture 1
0x31
TC7 OVF
Overflow/Underflow
0x32
TC7 MC0
Match/Capture 0
0x33
TC7 MC1
Match/Capture 1
0x34
ADC RESRDY
Result Ready
0x35
ADC WINMON
Window Monitor
0x36
AC COMP0
Comparator 0
0x37
AC COMP1
Comparator 1
0x38
AC WIN
Window 0
0x39
DAC EMPTY
Data Buffer Empty
0x3A
PTC EOC
End of Conversion
0x3B
PTC WCOMP
Window Comparator
0x3C-0xFF
Reserved
z
Bits 15:9 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 8 – SWEVT: Software Event
This bit is used to insert a software event on the channel selected by the CHANNEL.CHANNEL bit group.
This bit must be written together with CHANNEL.CHANNEL using a 16-bit write.
Writing a zero to this bit has no effect.
Writing a one to this bit will trigger a software event for the corresponding channel.
This bit will always return zero when read.
z
Bits 7:0 – CHANNEL: Channel Selection
These bits are used to select the channel to be set up or read from.
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Table 22-4. Channel Selection
Value
Channel Number
0x00
0
0x01
1
0x02
2
0x03
3
0x04
4
0x05
5
0x06
6
0x07
7
0x08-0xFF
Reserved
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22.8.3 User Multiplexer
This register is used to configure a specified event user. To write to this register, do a single 16-bit write of all the
configuration and event user selection data.
To read from this register, first do an 8-bit write to the USER.USER bit group specifying the event user configuration to be
read, and then read USER.
Name:
USER
Offset:
0x08
Reset:
0x0000
Property:
Write-protected
Bit
15
14
13
12
11
10
9
8
CHANNEL[7:0]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
USER[7:0]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Reset
z
Bits 15:8 – CHANNEL: Channel Event Selection
These bits are used to select the channel to connect to the event user.
Note that to select channel n, the value (n+1) must be written to the USER.CHANNEL bit group.
Table 22-5. Channel Event Selection
Value
Channel Number
0x00
No channel output selected
0x01
0
0x02
1
0x03
2
0x04
3
0x05
4
0x06
5
0x07
6
0x08
7
0x09-0xFF
Reserved
z
Bits 7:0 – USER: User Multiplexer Selection
These bits select the event user to be configured with a channel, or the event user to read the channel value from.
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Table 22-6. User Multiplexer Selection
USER[7:0]
User Multiplexer
Description
Path Type
0x00
TC0
Asynchronous, synchronous and resynchronized paths
0x01
TC1
Asynchronous, synchronous and resynchronized paths
0x02
TC2
Asynchronous, synchronous and resynchronized paths
0x03
TC3
Asynchronous, synchronous and resynchronized paths
0x04
TC4
Asynchronous, synchronous and resynchronized paths
0x05
TC5
Asynchronous, synchronous and resynchronized paths
0x06
TC6
Asynchronous, synchronous and resynchronized paths
0x07
TC7
Asynchronous, synchronous and resynchronized paths
0x08
ADC START
ADC start conversion
Asynchronous path only
0x09
ADC SYNC
Flush ADC
Asynchronous path only
0x0A
AC COMP0
Start comparator 0
Asynchronous path only
0x0B
AC COMP1
Start comparator 1
Asynchronous path only
0x0C
DAC START
DAC start conversion
Asynchronous path only
0x0D
PTC STCONV
PTC start conversion
Asynchronous path only
0x0E-0xFF
Reserved
Reserved
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22.8.4 Channel Status
Name:
CHSTATUS
Offset:
0x0C
Reset:
0x000000FF
Property:
–
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
CHBUSY7
CHBUSY6
CHBUSY5
CHBUSY4
CHBUSY3
CHBUSY2
CHBUSY1
CHBUSY0
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
USRRDY7
USRRDY6
USRRDY5
USRRDY4
USRRDY3
USRRDY2
USRRDY1
USRRDY0
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bits 31:16 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 15:8 – CHBUSYx: Channel Busy x
This bit is cleared when channel x is idle
This bit is set if an event on channel x has not been handled by all event users connected to channel x.
z
Bits 7:0 – USRRDYx: User Ready for Channel x
This bit is cleared when at least one of the event users connected to the channel is not ready.
This bit is set when all event users connected to channel x are ready to handle incoming events on channel x.
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22.8.5 Interrupt Enable Clear
This register allows the user to disable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Set register (INTENSET).
Name:
INTENCLR
Offset:
0x10
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
EVD7
EVD6
EVD5
EVD4
EVD3
EVD2
EVD1
EVD0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
OVR7
OVR6
OVR5
OVR4
OVR3
OVR2
OVR1
OVR0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Access
Access
Reset
z
Bits 31:16 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 15:8 – EVDx: Event Detected Channel x Interrupt Enable
0: The Event Detected Channel x interrupt is disabled.
1: The Event Detected Channel x interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Event Detected Channel x Interrupt Enable bit, which disables the Event
Detected Channel x interrupt.
z
Bits 7:0 – OVRx: Overrun Channel x Interrupt Enable
0: The Overrun Channel x interrupt is disabled.
1: The Overrun Channel x interrupt is enabled.
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Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Overrun Channel x Interrupt Enable bit, which disables the Overrun Channel
x interrupt.
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22.8.6 Interrupt Enable Set
This register allows the user to enable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Clear register (INTENCLR).
Name:
INTENSET
Offset:
0x14
Reset:
0x00000000
Property:
Write-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
EVD7
EVD6
EVD5
EVD4
EVD3
EVD2
EVD1
EVD0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
OVR7
OVR6
OVR5
OVR4
OVR3
OVR2
OVR1
OVR0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Access
Access
Reset
z
Bits 31:16 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 15:8 – EVDx: Event Detected Channel x Interrupt Enable
0: The Event Detected Channel x interrupt is disabled.
1: The Event Detected Channel x interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Event Detected Channel x Interrupt Enable bit, which enables the Event
Detected Channel x interrupt.
z
Bits 7:0 – OVRx: Overrun Channel x Interrupt Enable
0: The Overrun Channel x interrupt is disabled.
1: The Overrun Channel x interrupt is enabled.
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Writing a zero to this bit has no effect.
Writing a one to this bit will set the Overrun Channel x Interrupt Enable bit, which enables the Overrun Channel x
interrupt.
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22.8.7 Interrupt Flag Status and Clear
Name:
INTFLAG
Offset:
0x18
Reset:
0x00000000
Property:
–
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
EVD7
EVD6
EVD5
EVD4
EVD3
EVD2
EVD1
EVD0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
OVR7
OVR6
OVR5
OVR4
OVR3
OVR2
OVR1
OVR0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Access
Access
Reset
z
Bits 31:16 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 15:8 – EVDx: Event Detected Channel x
This flag is set on the next CLK_EVSYS_APB cycle when an event is being propagated through the channel, and
an interrupt request will be generated if INTENCLR/SET.EVDx is one.
When the event channel path is asynchronous, the EVDx interrupt flag will not be set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Event Detected Channel n interrupt flag.
z
Bits 7:0 – OVRx: Overrun Channel x
This flag is set on the next CLK_EVSYS cycle after an overrun channel condition occurs, and an interrupt request
will be generated if INTENCLR/SET.OVRx is one.
There are two possible overrun channel conditions:
z
One or more of the event users on channel x are not ready when a new event occurs
z
An event happens when the previous event on channel x has not yet been handled by all event users
When the event channel path is asynchronous, the OVRx interrupt flag will not be set.
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Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Overrun Channel x interrupt flag.
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23.
SERCOM – Serial Communication Interface
23.1
Overview
The serial communication interface (SERCOM) can be configured to support a number of modes; I2C, SPI and USART.
Once configured and enabled, all SERCOM resources are dedicated to the selected mode.
The SERCOM serial engine consists of a transmitter and receiver, baud-rate generator and address matching
functionality. It can be configured to use the internal generic clock or an external clock, making operation in all sleep
modes possible.
23.2
Features
z Combined interface configurable as one of the following:
I2C – Two-wire serial interface
z SMBus™ compatible.
z SPI – Serial peripheral interface
z USART – Universal synchronous and asynchronous serial receiver and transmitter
z
z Single transmit buffer and double receive buffer
z Baud-rate generator
z Address match/mask logic
z Operational in all sleep modes
23.3
Block Diagram
Figure 23-1. SERCOM Block Diagram
SERCOM
Register Interface
CONTROL/STATUS
Mode Specific
TX/RX DATA
BAUD/ADDR
Serial Engine
Mode n
Mode 1
Baud Rate
Generator
Transmitter
PAD[3:0]
Mode 0
Address
Match
Receiver
23.4
Signal Description
See the respective SERCOM mode chapters for details:
z
“SERCOM USART – SERCOM Universal Synchronous and Asynchronous Receiver and Transmitter” on page
344
z
“SERCOM SPI – SERCOM Serial Peripheral Interface” on page 369
z
“SERCOM I2C – SERCOM Inter-Integrated Circuit” on page 394
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23.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
23.5.1 I/O Lines
Using the SERCOM I/O lines requires the I/O pins to be configured using port configuration (PORT). Refer to “PORT” on
page 287 for details.
From Figure 23-1 one can see that the SERCOM has four internal pads, PAD[3:0]. The signals from I2C, SPI and USART
are routed through these SERCOM pads via a multiplexer. The configuration of the multiplexer is available from the
different SERCOM modes. Refer to the mode specific chapters for details:
z
“SERCOM USART – SERCOM Universal Synchronous and Asynchronous Receiver and Transmitter” on page
344
z
“SERCOM SPI – SERCOM Serial Peripheral Interface” on page 369
z
“SERCOM I2C – SERCOM Inter-Integrated Circuit” on page 394
23.5.2 Power Management
The SERCOM can operate in any sleep mode.SERCOM interrupts can be used to wake up the device from sleep
modes. Refer to “PM – Power Manager” on page 107 for details on the different sleep modes.
23.5.3 Clocks
The SERCOM bus clock (CLK_SERCOMx_APB) is enabled by default, and can be enabled and disabled in the Power
Manager. Refer to “PM – Power Manager” on page 107 for details.
Two generic clocks are used by the SERCOM: GCLK_SERCOMx_CORE and GCLK_SERCOMx_SLOW. The core clock
(GCLK_SERCOMx_CORE) is required to clock the SERCOM while operating as a master, while the slow clock
(GCLK_SERCOMx_SLOW) is only required for certain functions. See specific mode chapters for details.
These clocks must be configured and enabled in the Generic Clock Controller (GCLK) before using the SERCOM. Refer
to “GCLK – Generic Clock Controller” on page 85 for details.
These generic clocks are asynchronous to the user interface clock (CLK_SERCOMx_APB). Due to this asynchronicity,
writes to certain registers will require synchronization between the clock domains. Refer to “Synchronization” on page
343 for further details.
23.5.4 DMA
Not applicable.
23.5.5 Interrupts
The interrupt request line is connected to the Interrupt Controller. Using the SERCOM interrupts requires the Interrupt
Controller to be configured first. Refer to “Nested Vector Interrupt Controller” on page 30 for details.
23.5.6 Events
Not applicable.
23.5.7 Debug Operation
When the CPU is halted in debug mode, the SERCOM continues normal operation. If the SERCOM is configured in a
way that requires it to be periodically serviced by the CPU through interrupts or similar, improper operation or data loss
may result during debugging. The SERCOM can be forced to halt operation during debugging.
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23.5.8 Register Access Protection
All registers with write-access are optionally write-protected by the Peripheral Access Controller (PAC), except the
following registers:
z
Interrupt Flag Status and Clear register (INTFLAG)
z
Address register (ADDR)
z
Data register (DATA)
Write-protection is denoted by the Write-Protection property in the register description.
When the CPU is halted in debug mode, all write-protection is automatically disabled. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
23.5.9 Analog Connections
Not applicable.
23.6
Functional Description
23.6.1 Principle of Operation
The basic structure of the SERCOM serial engine is shown in Figure 23-2. Fields shown in capital letters are
synchronous to the system clock and accessible by the CPU, while fields with lowercase letters can be configured to run
on the GCLK_SERCOMx_CORE clock or an external clock.
Figure 23-2. SERCOM Serial Engine
Transmitter
Selectable
Internal Clk
(GCLK)
Ext Clk
BAUD
Address Match
TX DATA
ADDR/ADDRMASK
baud rate generator
1/- /2- /16
tx shift register
Receiver
rx shift register
==
status
Baud Rate Generator
STATUS
rx buffer
RX DATA
The transmitter consists of a single write buffer and a shift register. The receiver consists of a two-level receive buffer and
a shift register. The baud-rate generator is capable of running on the GCLK_SERCOMx_CORE clock or an external
clock. Address matching logic is included for SPI and I2C operation.
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23.6.2 Basic Operation
23.6.2.1 Initialization
The SERCOM must be configured to the desired mode by writing to the Operating Mode bits in the Control A register
(CTRLA.MODE). Refer to Figure 23-1 for details.
Table 23-1. SERCOM Modes
CTRLA.MODE
Description
0x0
USART with external clock
0x1
USART with internal clock
0x2
SPI in slave operation
0x3
SPI in master operation
0x4
I2C slave operation
0x5
I2C master operation
0x6-0x7
Reserved
For further initialization information, see the respective SERCOM mode chapters.
23.6.2.2 Enabling, Disabling and Resetting
The SERCOM is enabled by writing a one to the Enable bit in the Control A register (CTRLA.ENABLE). The SERCOM is
disabled by writing a zero to CTRLA.ENABLE.
The SERCOM is reset by writing a one to the Software Reset bit in the Control A register (CTRLA.SWRST). All registers
in the SERCOM, except DBGCTRL, will be reset to their initial state, and the SERCOM will be disabled. Refer to the
CTRLA register descriptions for details.
23.6.2.3 Clock Generation – Baud-Rate Generator
The baud-rate generator, as shown in Figure 23-3, is used for internal clock generation for asynchronous and
synchronous communication. The generated output frequency (fBAUD) is determined by the Baud register (BAUD) setting
and the baud reference frequency (fREF). The baud reference clock is the serial engine clock, and it can be internal or
external.
For asynchronous operation, the /16 (divide-by-16) output is used when transmitting and the /1 (divide-by-1) output is
used when receiving. For synchronous operation the /2 (divide-by-2) output is used. This functionality is automatically
configured, depending on the selected operating mode.
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Figure 23-3. Baud Rate Generator
Selectable
Internal Clk
(GCLK)
Baud Rate Generator
1
Ext Clk
fref
Base
Period
0
/2
/1
CTRLA.MODE[0]
/8
/2
/16
0
Tx Clk
1
1
CTRLA.CMODE
0
1
Clock
Recovery
Rx Clk
0
Table 23-2 contains equations for calculating the baud rate (in bits per second) and for calculating the BAUD register
value for each mode of operation.
For asynchronous mode, the BAUD register value is 16 bits (0 to 65,535), while for synchronous mode, the BAUD
register value is 8 bits (0 to 255).
Table 23-2. Baud Rate Equations
Operating Mode
Condition
f
Asynchronous
f
Synchronous
BAUD
BAUD
≤
≤
Baud Rate (Bits Per Second)
f
REF
16
f
REF
2
f
f
f
BAUD Register Value Calculation
BAUD ⎞
⎛
=
⎜1 −
⎟
BAUD
16 ⎝ 65,536 ⎠
BAUD
=
REF
f
REF
2( BAUD + 1)
⎛
BAUD = 65,536⎜1 − 16
⎜
⎝
BAUD =
f
2 f
REF
f
f
BAUD
REF
⎞
⎟
⎟
⎠
−1
BAUD
Asynchronous Mode BAUD Value Selection
The formula given for fBAUD calculates the average frequency over 65,536 fREF cycles. Although the BAUD register can be
set to any value between 0 and 65,536, the values that will change the average frequency of fBAUD over a single frame
are more constrained. The BAUD register values that will affect the average frequency over a single frame lead to an
integer increase in the cycles per frame (CPF)
CPF =
f
f
REF
(D + S )
BAUD
where
z
D represent the data bits per frame
z
S represent the sum of start and first stop bits, if present
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Table 23-3 shows the BAUD register value versus baud frequency at a serial engine frequency of 48MHz. This assumes
a D value of 8 bits and an S value of 2 bits (10 bits, including start and stop bits).
Table 23-3. BAUD Register Value vs. Baud Frequency
BAUD Register Value
Serial Engine CPF
fBAUD at 48MHz Serial Engine Frequency (fREF)
0 – 406
160
3MHz
407 – 808
161
2.981MHz
809 – 1205
162
2.963MHz
65206
31775
15.11kHz
65207
31871
15.06kHz
65208
31969
15.01kHz
...
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23.6.3 Additional Features
23.6.3.1 Address Match and Mask
The SERCOM address match and mask feature is capable of matching one address with a mask, two unique addresses
or a range of addresses, based on the mode selected. The match uses seven or eight bits, depending on the mode.
Address With Mask
An address written to the Address bits in the Address register (ADDR.ADDR) with a mask written to the Address Mask
bits in the Address register (ADDR.ADDRMASK) will yield an address match. All bits that are masked are not included in
the match. Note that setting the ADDR.ADDRMASK to all zeros will match a single unique address, while setting
ADDR.ADDRMASK to all ones will result in all addresses being accepted.
Figure 23-4. Address With Mask
ADDR
ADDRMASK
==
Match
rx shift register
Two Unique Addresses
The two addresses written to ADDR and ADDRMASK will cause a match.
Figure 23-5. Two Unique Addresses
ADDR
==
Match
rx shift register
==
ADDRMASK
Address Range
The range of addresses between and including ADDR.ADDR and ADDR.ADDRMASK will cause a match. ADDR.ADDR
and ADDR.ADDRMASK can be set to any two addresses, with ADDR.ADDR acting as the upper limit and
ADDR.ADDRMASK acting as the lower limit.
Figure 23-6. Address Range
ADDRMASK
rx shift register
ADDR
== Match
23.6.4 DMA Operation
Not applicable.
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23.6.5 Interrupts
Interrupt sources are mode-specific. See the respective SERCOM mode chapters for details.
Each interrupt source has an interrupt flag associated with it. The interrupt flag in the Interrupt Flag Status and Clear
register (INTFLAG) is set when the interrupt condition occurs. Each interrupt can be individually enabled by writing a one
to the corresponding bit in the Interrupt Enable Set register (INTENSET), and disabled by writing a one to the
corresponding bit in the Interrupt Enable Clear register (INTENCLR). An interrupt request is generated when the interrupt
flag is set and the corresponding interrupt is enabled. The interrupt request remains active until the interrupt flag is
cleared, the interrupt is disabled or the SERCOM is reset. See the register description for details on how to clear interrupt
flags.
The SERCOM has one common interrupt request line for all the interrupt sources. The user must read the INTFLAG
register to determine which interrupt condition is present.
Note that interrupts must be globally enabled for interrupt requests to be generated. Refer to “Nested Vector Interrupt
Controller” on page 30 for details.
23.6.6 Events
Not applicable.
23.6.7 Sleep Mode Operation
The peripheral can operate in any sleep mode where the selected serial clock is running. This clock can be external or
generated by the internal baud-rate generator.
The SERCOM interrupts can be used to wake up the device from sleep modes. Refer to the different SERCOM mode
chapters for details.
23.6.8 Synchronization
Due to the asynchronicity between CLK_SERCOMx_APB and GCLK_SERCOMx_CORE, some registers must be
synchronized when accessed. A register can require:
z
Synchronization when written
z
Synchronization when read
z
Synchronization when written and read
z
No synchronization
When executing an operation that requires synchronization, the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set immediately, and cleared when synchronization is complete. The Synchronization
Ready interrupt can be used to signal when synchronization is complete.
If an operation that requires synchronization is executed while STATUS.SYNCBUSY is one, the bus will be stalled. All
operations will complete successfully, but the CPU will be stalled and interrupts will be pending as long as the bus is
stalled.
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24.
SERCOM USART – SERCOM Universal Synchronous and Asynchronous
Receiver and Transmitter
24.1
Overview
The universal synchronous and asynchronous receiver and transmitter (USART) is one of the available modes in the
Serial Communication Interface (SERCOM).
Refer to “SERCOM – Serial Communication Interface” on page 336 for details.
The USART uses the SERCOM transmitter and receiver configured as shown in Figure 24-1. Fields shown in capital
letters are synchronous to the CLK_SERCOMx_APB and accessible by the CPU, while fields with lowercase letters can
be configured to run on the internal generic clock or an external clock.
The transmitter consists of a single write buffer, a shift register and control logic for handling different frame formats. The
write buffer allows continuous data transmission without any delay between frames.
The receiver consists of a two-level receive buffer and a shift register. Status information for the received data is
available for error checking. Data and clock recovery units ensure robust synchronization and noise filtering during
asynchronous data reception.
24.2
Features
z Full-duplex operation
z Asynchronous (with clock reconstruction) or synchronous operation
z Internal or external clock source for asynchronous and synchronous operation
z Baud-rate generator
z Supports serial frames with 5, 6, 7, 8 or 9 data bits and 1 or 2 stop bits
z Odd or even parity generation and parity check
z Selectable LSB- or MSB-first data transfer
z Buffer overflow and frame error detection
z Noise filtering, including false start-bit detection and digital low-pass filter
z Can operate in all sleep modes
z Operation at speeds up to half the system clock for internally generated clocks
z Operation at speeds up to the system clock for externally generated clocks
z Start-of-frame detection
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24.3
Block Diagram
Figure 24-1. USART Block Diagram
BAUD
Internal Clk
(GCLK)
TX DATA
baud rate generator
/1 - /2 - /16
tx shift register
TxD
rx shift register
RxD
XCK
Signal name
24.4
status
rx buffer
STATUS
RX DATA
Signal Description
Signal Name
Type
Description
PAD[3:0]
Digital I/O
General SERCOM pins
Refer to “I/O Multiplexing and Considerations” on page 16 for details on the pin mapping for this peripheral. One signal
can be mapped on several pins.
24.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
24.5.1 I/O Lines
Using the USART’s I/O lines requires the I/O pins to be configured using port configuration (PORT).
Refer to “PORT” on page 287 for details.
When the SERCOM is used in USART mode, the pins should be configured according to Table 24-1. If the receiver or
transmitter is disabled, these pins can be used for other purposes.
Table 24-1. USART Pin Configuration
Pin
Pin Configuration
TxD
Output
RxD
Input
XCK
Output or input
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The combined configuration of PORT and the Transmit Data Pinout and Receive Data Pinout bit groups (refer to the
Control A register description) will define the physical position of the USART signals in Table 24-1.
24.5.2 Power Management
The USART can continue to operate in any sleep mode where the selected source clock is running. The USART
interrupts can be used to wake up the device from sleep modes. The events can trigger other operations in the system
without exiting sleep modes. Refer to “PM – Power Manager” on page 107 for details on the different sleep modes.
24.5.3 Clocks
The SERCOM bus clock (CLK_SERCOMx_APB, where x represents the specific SERCOM instance number) can be
enabled and disabled in the Power Manager, and the default state of CLK_SERCOMx_APB can be found in the
Peripheral Clock Masking section in “PM – Power Manager” on page 107.
A generic clock (GCLK_SERCOMx_CORE) is required to clock the SERCOMx_CORE. This clock must be configured
and enabled in the Generic Clock Controller before using the SERCOMx_CORE. Refer to “GCLK – Generic Clock
Controller” on page 85 for details.
This generic clock is asynchronous to the bus clock (CLK_SERCOMx_APB). Due to this asynchronicity, writes to certain
registers will require synchronization between the clock domains. Refer to “Synchronization” on page 353 for further
details.
24.5.4 DMA
Not applicable.
24.5.5 Interrupts
The interrupt request line is connected to the Interrupt Controller. Using the USART interrupts requires the Interrupt
Controller to be configured first. Refer to “Nested Vector Interrupt Controller” on page 30 for details.
24.5.6 Events
Not applicable.
24.5.7 Debug Operation
When the CPU is halted in debug mode, the USART continues normal operation. If the USART is configured in a way
that requires it to be periodically serviced by the CPU through interrupts or similar, improper operation or data loss may
result during debugging. The USART can be forced to halt operation during debugging.
Refer to DBGCTRL for details.
24.5.8 Register Access Protection
All registers with write-access are optionally write-protected by the Peripheral Access Controller (PAC), except the
following registers:
z
Interrupt Flag Status and Clear register (INTFLAG)
z
Status register (STATUS)
z
Data register (DATA)
Write-protection is denoted by the Write-Protection property in the register description.
When the CPU is halted in debug mode, all write-protection is automatically disabled.
Write-protection does not apply for accesses through an external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
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24.5.9 Analog Connections
Not applicable.
24.6
Functional Description
24.6.1 Principle of Operation
The USART uses three communication lines for data transfer:
z
RxD for receiving
z
TxD for transmitting
z
XCK for the transmission clock in synchronous operation
USART data transfer is frame based, where a serial frame consists of:
z
1 start bit
z
5, 6, 7, 8 or 9 data bits
z
MSB or LSB first
z
No, even or odd parity bit
z
1 or 2 stop bits
A frame starts with the start bit followed by one character of data bits. If enabled, the parity bit is inserted after the data
bits and before the first stop bit. One frame can be directly followed by a new frame, or the communication line can return
to the idle (high) state. Figure 24-2 illustrates the possible frame formats. Bits inside brackets are optional.
Figure 24-2. Frame Formats
Frame
(IDLE)
St
0
1
2
3
4
[5]
[6]
[7]
[8]
[P]
Sp1
[Sp2]
(St/IDLE)
St Start bit; always low
(n) Data bits; 0 to 8
P Parity bit; odd or even
Sp
Stop bit; always high
IDLE No transfers on the communication line; always high in this state
24.6.2 Basic Operation
24.6.2.1 Initialization
The following registers are enable-protected, meaning they can only be written when the USART is disabled
(CTRLA.ENABLE is zero):
z
Control A register (CTRLA), except the Enable (ENABLE) and Software Reset (SWRST) bits
z
Control B register (CTRLB), except the Receiver Enable (RXEN) and Transmitter Enable (TXEN) bits
z
Baud register (BAUD)
Any writes to these registers when the USART is enabled or is being enabled (CTRLA.ENABLE is one) will be discarded.
Writes to these registers) while the peripheral is being disabled will be completed after the disabling is complete.
Before the USART is enabled, it must be configured, as outlined in the following steps:
z
USART mode with external or internal clock must be selected first by writing 0x0 or 0x1 to the Operating Mode bit
group in the Control A register (CTRLA.MODE)
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z
Communication mode (asynchronous or synchronous) must be selected by writing to the Communication Mode bit
in the Control A register (CTRLA.CMODE)
z
SERCOM pad to use for the receiver must be selected by writing to the Receive Data Pinout bit group in the
Control A register (CTRLA.RXPO)
z
SERCOM pads to use for the transmitter and external clock must be selected by writing to the Transmit Data
Pinout bit in the Control A register (CTRLA.TXPO)
z
Character size must be selected by writing to the Character Size bit group in the Control B register
(CTRLB.CHSIZE)
z
MSB- or LSB-first data transmission must be selected by writing to the Data Order bit in the Control A register
(CTRLA.DORD)
z
When parity mode is to be used, even or odd parity must be selected by writing to the Parity Mode bit in the Control
B register (CTRLB.PMODE) and enabled by writing 0x1 to the Frame Format bit group in the Control A register
(CTRLA.FORM)
z
Number of stop bits must be selected by writing to the Stop Bit Mode bit in the Control B register
(CTRLB.SBMODE)
z
When using an internal clock, the Baud register (BAUD) must be written to generate the desired baud rate
z
The transmitter and receiver can be enabled by writing ones to the Receiver Enable and Transmitter Enable bits in
the Control B register (CTRLB.RXEN and CTRLB.TXEN)
24.6.2.2 Enabling, Disabling and Resetting
The USART is enabled by writing a one to the Enable bit in the Control A register (CTRLA.ENABLE). The USART is
disabled by writing a zero to CTRLA.ENABLE.
The USART is reset by writing a one to the Software Reset bit in the Control A register (CTRLA.SWRST). All registers in
the USART, except DBGCTRL, will be reset to their initial state, and the USART will be disabled. Refer to the CTRLA
register for details.
24.6.2.3 Clock Generation and Selection
For both synchronous and asynchronous modes, the clock used for shifting and sampling data can be generated
internally by the SERCOM baud-rate generator or supplied externally through the XCK line. Synchronous mode is
selected by writing a one to the Communication Mode bit in the Control A register (CTRLA.CMODE) and asynchronous
mode is selected by writing a zero to CTRLA.CMODE. The internal clock source is selected by writing 0x1 to the
Operation Mode bit group in the Control A register (CTRLA.MODE) and the external clock source is selected by writing
0x0 to CTRLA.MODE.
The SERCOM baud-rate generator is configured as shown in Figure 24-3. When CTRLA.CMODE is zero, the baud-rate
generator is automatically set to asynchronous mode and the 16-bit Baud register value is used. When CTRLA.CMODE
is one, the baud-rate generator is automatically set to synchronous mode and the eight LSBs of the Baud register are
used. Refer to “Clock Generation – Baud-Rate Generator” on page 339 for details on configuring the baud rate.
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Figure 24-3. Clock Generation
Internal C lk
(G C LK )
B au d R ate G enerator
1
0
B ase
Period
/2
/1
C T R LA .M O D E [0]
/8
/2
/16
0
Tx C lk
1
1
XCK
C TR LA .C M O D E
0
1
R x C lk
0
Synchronous Clock Operation
When synchronous mode is used, the CTRLA.MODE bit group controls whether the transmission clock (XCK line) is an
input or output. The dependency between the clock edges and data sampling or data change is the same for internal and
external clocks. Data input on the RxD pin is sampled at the opposite XCK clock edge as data is driven on the TxD pin.
The Clock Polarity bit in the Control A register (CTRLA.CPOL) selects which XCK clock edge is used for RxD sampling
and which is used for TxD change. As shown in Figure 24-4, when CTRLA.CPOL is zero, the data will be changed on the
rising XCK edge and sampled on the falling XCK edge. If CTRLA.CPOL is one, the data will be changed on the falling
edge of XCK and sampled on the rising edge of XCK.
Figure 24-4. Synchronous Mode XCK Timing
Change
XCK
CTRLA.CPOL=1
RxD / TxD
Sample
Change
XCK
CTRLA.CPOL=0
RxD / TxD
Sample
When the clock is provided through XCK (CTRLA.MODE is 0x0), the shift registers operate directly on the XCK clock.
This means that XCK is not synchronized with the system clock and, therefore, can operate at frequencies up to the
system frequency.
24.6.2.4 Data Register
The USART Transmit Data register (TxDATA) and USART Receive Data register(RxDATA) share the same I/O address,
referred to as the Data register (DATA). Writing the DATA register will update the Transmit Data register. Reading the
DATA register will return the contents of the Receive Data register.
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24.6.2.5 Data Transmission
A data transmission is initiated by loading the DATA register with the data to be sent. The data in TxDATA is moved to
the shift register when the shift register is empty and ready to send a new frame. When the shift register is loaded with
data, one complete frame will be transmitted.
The Transmit Complete interrupt flag in the Interrupt Flag Status and Clear register (INTFLAG.TXC) is set, and the
optional interrupt is generated, when the entire frame plus stop bit(s) have been shifted out and there is no new data
written to the DATA register.
The DATA register should only be written when the Data Register Empty flag in the Interrupt Flag Status and Clear
register (INTFLAG.DRE) is set, which indicates that the register is empty and ready for new data.
Disabling the Transmitter
Disabling the transmitter will not become effective until any ongoing and pending transmissions are completed, i.e., when
the transmit shift register and TxDATA do not contain data to be transmitted. The transmitter is disabled by writing a zero
to the Transmitter Enable bit in the Control B register (CTRLB.TXEN).
24.6.2.6 Data Reception
The receiver starts data reception when a valid start bit is detected. Each bit that follows the start bit will be sampled at
the baud rate or XCK clock, and shifted into the receive shift register until the first stop bit of a frame is received. When
the first stop bit is received and a complete serial frame is present in the receive shift register, the contents of the shift
register will be moved into the two-level receive buffer. The Receive Complete interrupt flag in the Interrupt Flag Status
and Clear register (INTFLAG.RXC) is set, and the optional interrupt is generated. A second stop bit will be ignored by the
receiver.
The received data can be read by reading the DATA register. DATA should not be read unless the Receive Complete
interrupt flag is set.
Disabling the Receiver
Disabling the receiver by writing a zero to the Receiver Enable bit in the Control B register (CTRLB.RXEN) will flush the
two-level receive buffer, and data from ongoing receptions will be lost.
Error Bits
The USART receiver has three error bits. The Frame Error (FERR), Buffer Overflow (BUFOVF) and Parity Error (PERR)
bits can be read from the Status (STATUS) register. Upon error detection, the corresponding bit will be set until it is
cleared by writing a one to it. These bits are also automatically cleared when the receiver is disabled.
There are two methods for buffer overflow notification. When the immediate buffer overflow notification bit (CTRLA.IBON)
is set, STATUS.BUFOVF is raised immediately upon buffer overflow. Software can then empty the receive FIFO by
reading RxDATA until the receive complete interrupt flag (INTFLAG.RXC) goes low.
When CTRLA.IBON is zero, the buffer overflow condition travels with data through the receive FIFO. After the received
data is read, STATUS.BUFOVF will be set along with INTFLAG.RXC.
Asynchronous Data Reception
The USART includes a clock recovery and data recovery unit for handling asynchronous data reception. The clock
recovery logic is used to synchronize the incoming asynchronous serial frames at the RxD pin to the internally generated
baud-rate clock. The data recovery logic samples and applies a low-pass filter to each incoming bit, thereby improving
the noise immunity of the receiver. The asynchronous reception operational range depends on the accuracy of the
internal baud-rate clock, the rate of the incoming frames and the frame size (in number of bits).
Asynchronous Operational Range
The operational range of the receiver depends on the difference between the received bit rate and the internally
generated baud rate. If the baud rate of an external transmitter is too high or too low compared to the internally generated
baud rate, the receiver will not be able to synchronize the frames to the start bit.
There are two possible sources for a mismatch in baud rate. The reference clock will always have some minor instability.
In addition, the baud-rate generator can not always do an exact division of the reference clock frequency to get the baud
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rate desired. In this case, the BAUD register value should be selected to give the lowest possible error. Refer to
“Asynchronous Mode BAUD Value Selection” on page 340 for details.
Recommended maximum receiver baud-rate errors for various character sizes are shown in the table below.
Table 24-2. Asynchronous Receiver Error for x16 oversampling
D
(Data bits + Parity)
RSLOW(%)
RFAST(%)
Max Total Error (%)
Recommended Max
Rx Error (%)
5
94.12
107.69
+5.88/-7.69
±2.5
6
94.92
106.67
+5.08/-6.67
±2.0
7
95.52
105.88
+4.48/-5.88
±2.0
8
96.00
105.26
+4.00/-5.26
±2.0
9
96.39
104.76
+3.61/-4.76
±1.5
10
96.70
104.35
+3.30/-4.35
±1.5
The recommended maximum receiver baud-rate error assumes that the receiver and transmitter equally divide the
maximum total error.
The following equations can be used to calculate the ratio of the incoming data rate and internal receiver baud rate:
R
SLOW
=
16( D + 1)
16( D + 1) + 6
R
FAST
=
16( D + 2)
16( D + 1) + 8
where:
z
D is the sum of character size and parity size (D = 5 to 10 bits)
z
RSLOW is the ratio of the slowest incoming data rate that can be accepted in relation to the receiver baud rate
z
RFAST is the ratio of the fastest incoming data rate that can be accepted in relation to the receiver baud rate
24.6.3 Additional Features
24.6.3.1 Parity
Even or odd parity can be selected for error checking by writing 0x1 to the Frame Format bit group in the Control A
register (CTRLA.FORM). If even parity is selected by writing a zero to the Parity Mode bit in the Control B register
(CTRLB.PMODE), the parity bit of the outgoing frame is set to one if the number of data bits that are one is odd (making
the total number of ones even). If odd parity is selected by writing a one to CTRLB.PMODE, the parity bit of the outgoing
frame is set to one if the number of data bits that are one is even (making the total number of ones odd).
When parity checking is enabled, the parity checker calculates the parity of the data bits in incoming frames and
compares the result with the parity bit of the corresponding frame. If a parity error is detected, the Parity Error bit in the
Status register (STATUS.PERR) is set.
24.6.3.2 Loop-back Mode
By configuring the Receive Data Pinout (CTRLA.RXPO) and Transmit Data Pinout (CTRLA.TXPO) to use the same data
pins for transmit and receive, loop-back is achieved. The loop-back is through the pad, so the signal is also available
externally.
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24.6.3.3 Start-of-Frame Detection
The USART start-of-frame detector can wake up the CPU when it detects a start bit. In standby sleep mode, the internal
8MHz oscillator must be selected as the GCLK_SERCOMx_CORE source.
When a 1-to-0 transition is detected on RxD, the 8MHz Internal Oscillator is powered up and the USART clock is
enabled. After startup, the rest of the data frame can be received, provided that the baud rate is slow enough in relation
to the 8MHz Internal Oscillator start-up time. Refer to “Electrical Characteristics” on page 571 for details. The start-up
time of the 8MHz Internal Oscillator varies with supply voltage and temperature.
The USART start-of-frame detection works both in asynchronous and synchronous modes. It is enabled by writing a one
to the Start of Frame Detection Enable bit in the Control B register (CTRLB.SFDE). If the Receive Start Interrupt Enable
bit in the Interrupt Enable Set register (INTENSET.RXS) is set, the Receive Start interrupt is generated immediately
when a start is detected. When using start-of-frame detection without the Receive Start interrupt, start detection will force
the 8MHz Internal Oscillator and USART clock active while the frame is being received, but the CPU will not wakeup until
the Receive Complete interrupt is generated, if enabled.
24.6.4 Interrupts
The USART has the following interrupt sources:
z
Receive Start (RXS): this is an asynchronous interrupt and can be used to wake-up the device from any sleep
mode.
z
Receive Complete (RXC): this is an asynchronous interrupt and can be used to wake-up the device from any sleep
mode.
z
Transmit Complete (TXC): this is an asynchronous interrupt and can be used to wake-up the device from any
sleep mode.
z
Data Register Empty (DRE): this is an asynchronous interrupt and can be used to wake-up the device from any
sleep mode.
Each interrupt source has an interrupt flag associated with it. The interrupt flag in the Interrupt Flag Status and Clear
register (INTFLAG) is set when the interrupt condition occurs. Each interrupt can be individually enabled by writing a one
to the corresponding bit in the Interrupt Enable Set register (INTENSET), and disabled by writing a one to the
corresponding bit in the Interrupt Enable Clear register (INTENCLR). An interrupt request is generated when the interrupt
flag is set and the corresponding interrupt is enabled. The interrupt request remains active until the interrupt flag is
cleared, the interrupt is disabled or the USART is reset. See the register description for details on how to clear interrupt
flags.
The USART has one common interrupt request line for all the interrupt sources. The user must read INTFLAG to
determine which interrupt condition is present.
Note that interrupts must be globally enabled for interrupt requests to be generated. Refer to “Nested Vector Interrupt
Controller” on page 30 for details.
24.6.5 Events
Not applicable.
24.6.6 Sleep Mode Operation
When using internal clocking, writing the Run In Standby bit in the Control A register (CTRLA.RUNSTDBY) to one will
allow GCLK_SERCOMx_CORE to be enabled in all sleep modes. Any interrupt can wake up the device.
When using external clocking, writing a one to CTRLA.RUNSTDBY will allow the Receive Complete interrupt.to wake up
the device.
If CTRLA.RUNSTDBY is zero, the internal clock will be disabled when any ongoing transfer is finished. A Transfer
Complete interrupt can wake up the device. When using external clocking, this will be disconnected when any ongoing
transfer is finished, and all reception will be dropped.
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24.6.7 Synchronization
Due to the asynchronicity between CLK_SERCOMx_APB and GCLK_SERCOMx_CORE, some registers must be
synchronized when accessed. A register can require:
z
Synchronization when written
z
Synchronization when read
z
Synchronization when written and read
z
No synchronization
When executing an operation that requires synchronization, the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set immediately, and cleared when synchronization is complete.
If an operation that requires synchronization is executed while STATUS.SYNCBUSY is one, the bus will be stalled. All
operations will complete successfully, but the CPU will be stalled and interrupts will be pending as long as the bus is
stalled.
The following bits need synchronization when written:
z
Software Reset bit in the Control A register (CTRLA.SWRST).
z
Enable bit in the Control A register (CTRLA.ENABLE).
z
Receiver Enable bit in the Control B register (CTRLB.RXEN).
z
Transmitter Enable bit in the Control B register (CTRLB.TXEN).
CTRLB.RXEN and CTRLB.TXEN behave somewhat differently than described above.
Refer to CTRLB register description for details.
Synchronization is denoted by the Write-Synchronized property in the register description.
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24.7
Offset
Register Summary
Name
0x00
Bit Pos.
7:0
0x01
RUNSTDBY
MODE[2:0]
ENABLE
SWRST
IBON
15:8
CTRLA
RXPO[1:0]
0x02
23:16
0x03
31:24
DORD
0x04
7:0
SBMODE
0x05
CTRLB
23:16
0x07
31:24
0x08
DBGCTRL
0x09
Reserved
0x0A
CMODE
FORM[3:0]
CHSIZE[2:0]
PMODE
15:8
0x06
CPOL
TXPO
SFDE
RXEN
7:0
TXEN
DBGSTOP
7:0
BAUD[7:0]
15:8
BAUD[15:8]
BAUD
0x0B
0x0C
INTENCLR
7:0
RXS
RXC
TXC
DRE
0x0D
INTENSET
7:0
RXS
RXC
TXC
DRE
0x0E
INTFLAG
7:0
RXS
RXC
TXC
DRE
0x0F
Reserved
BUFOVF
FERR
PERR
0x10
7:0
STATUS
0x11
15:8
0x12
Reserved
0x13
Reserved
0x14
Reserved
0x15
Reserved
0x16
Reserved
0x17
Reserved
0x18
7:0
SYNCBUSY
DATA[7:0]
DATA
0x19
15:8
0x1A
Reserved
0x1B
Reserved
0x1C
Reserved
0x1D
Reserved
0x1E
Reserved
0x1F
Reserved
DATA[8]
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24.8
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-Protected property in each individual register description. Refer to “Register Access Protection” on page 346
for details.
Some registers require synchronization when read and/or written. Synchronization is denoted by the Synchronized
property in each individual register description. Refer to “Synchronization” on page 353 for details.
Some registers are enable-protected, meaning they can only be written when the USART is disabled. Enable-protection
is denoted by the Enable-Protected property in each individual register description.
24.8.1 Control A
Name:
CTRLA
Offset:
0x00
Reset:
0x00000000
Property:
Enable-Protected, Write-Protected, Write-Synchronized
Bit
31
30
29
28
DORD
CPOL
CMODE
27
26
25
24
FORM[3:0]
Access
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
RXPO[1:0]
TXPO
Access
R
R
R/W
R/W
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
IBON
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ENABLE
SWRST
RUNSTDBY
Access
Reset
z
MODE[2:0]
R/W
R
R
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bit 31 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
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z
Bit 30 – DORD: Data Order
This bit indicates the data order when a character is shifted out from the Data register.
0: MSB is transmitted first.
1: LSB is transmitted first.
This bit is not synchronized.
z
Bit 29 – CPOL: Clock Polarity
This bit indicates the relationship between data output change and data input sampling in synchronous mode.
This bit is not synchronized.
Table 24-3. Clock Polarity
z
CPOL
TxD Change
RxD Sample
0x0
Rising XCK edge
Falling XCK edge
0x1
Falling XCK edge
Rising XCK edge
Bit 28 – CMODE: Communication Mode
This bit indicates asynchronous or synchronous communication.
0: Asynchronous communication.
1: Synchronous communication.
This bit is not synchronized.
z
Bits 27:24 – FORM[3:0]: Frame Format
These bits define the frame format.
These bits are not synchronized.
Table 24-4. Frame Format
FORM[3:0]
Description
0x0
USART frame
0x1
USART frame with parity
0x2-0xF
Reserved
z
Bits 23:22 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 21:20 – RXPO[1:0]: Receive Data Pinout
These bits define the receive data (RxD) pin configuration.
These bits are not synchronized.
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Table 24-5. Receive Data Pinout
RXPO[1:0]
Name
Description
0x0
PAD[0]
SERCOM PAD[0] is used for data reception
0x1
PAD[1]
SERCOM PAD[1] is used for data reception
0x2
PAD[2]
SERCOM PAD[2] is used for data reception
0x3
PAD[3]
SERCOM PAD[3] is used for data reception
z
Bits 19:17 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 16 – TXPO: Transmit Data Pinout
This bit defines the transmit data (TxD) and XCK pin configurations.
This bit is not synchronized.
Table 24-6. Transmit Data Pinout
TXPO
TxD Pin Location
XCK Pin Location (When Applicable)
0x0
PAD[0]
PAD[1]
0x1
PAD[2]
PAD[3]
z
Bits 15:9 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 8 – IBON: Immediate Buffer Overflow Notification
This bit controls when the buffer overflow status bit (STATUS.BUFOVF) is asserted when a buffer overflow occurs.
0: STATUS.BUFOVF is asserted when it occurs in the data stream.
1: STATUS.BUFOVF is asserted immediately upon buffer overflow.
z
Bit 7 – RUNSTDBY: Run In Standby
This bit defines the functionality in standby sleep mode.
This bit is not synchronized.
Table 24-7. Run In Standby
RUNSTDBY
External Clock
Internal Clock
0x0
External clock is disconnected when
ongoing transfer is finished. All
reception is dropped.
Generic clock is disabled when ongoing transfer is
finished. The device can wake up on Receive Start or
Transfer Complete interrupt.
0x1
Wake on Receive Start or Receive
Complete interrupt.
Generic clock is enabled in all sleep modes. Any
interrupt can wake up the device.
z
Bits 6:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 4:2 – MODE: Operating Mode
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These bits must be written to 0x0 or 0x1 to select the USART serial communication interface of the SERCOM.
0x0: USART with external clock.
0x1: USART with internal clock.
These bits are not synchronized.
z
Bit 1 – ENABLE: Enable
0: The peripheral is disabled or being disabled.
1: The peripheral is enabled or being enabled.
Due to synchronization, there is delay from writing CTRLA.ENABLE until the peripheral is enabled/disabled. The
value written to CTRLA.ENABLE will read back immediately and the Synchronization Busy bit in the Status register (STATUS.SYNCBUSY) will be set. STATUS.SYNCBUSY is cleared when the operation is complete.
This bit is not enable-protected.
z
Bit 0 – SWRST: Software Reset
0: There is no reset operation ongoing.
1: The reset operation is ongoing.
Writing a zero to this bit has no effect.
Writing a one to this bit resets all registers in the SERCOM, except DBGCTRL, to their initial state, and the SERCOM will be disabled.
Writing a one to CTRLA.SWRST will always take precedence, meaning that all other writes in the same write-operation will be discarded.
Due to synchronization, there is a delay from writing CTRLA.SWRST until the reset is complete. CTRLA.SWRST
and STATUS.SYNCBUSY will both be cleared when the reset is complete.
This bit is not enable-protected.
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24.8.2 Control B
Name:
CTRLB
Offset:
0x04
Reset:
0x00000000
Property:
Enable-Protected, Write-Protected, Write-Synchronized
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
RXEN
TXEN
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
PMODE
SFDE
Access
R
R
R/W
R
R
R
R/W
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
SBMODE
CHSIZE[2:0]
Access
R
R/W
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 31:18 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 17 – RXEN: Receiver Enable
0: The receiver is disabled or being enabled.
1: The receiver is enabled or will be enabled when the USART is enabled.
Writing a zero to this bit will disable the USART receiver. Disabling the receiver will flush the receive buffer and
clear the FERR, PERR and BUFOVF bits in the STATUS register.
Writing a one to CTRLB.RXEN when the USART is disabled will set CTRLB.RXEN immediately. When the USART
is enabled, CTRLB.RXEN will be cleared, and STATUS.SYNCBUSY will be set and remain set until the receiver is
enabled. When the receiver is enabled, CTRLB.RXEN will read back as one.
Writing a one to CTRLB.RXEN when the USART is enabled will set STATUS.SYNCBUSY, which will remain set
until the receiver is enabled, and CTRLB.RXEN will read back as one.
This bit is not enable-protected.
z
Bit 16 – TXEN: Transmitter Enable
0: The transmitter is disabled or being enabled.
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1: The transmitter is enabled or will be enabled when the USART is enabled.
Writing a zero to this bit will disable the USART transmitter. Disabling the transmitter will not become effective until
ongoing and pending transmissions are completed.
Writing a one to CTRLB.TXEN when the USART is disabled will set CTRLB.TXEN immediately. When the USART
is enabled, CTRLB.TXEN will be cleared, and STATUS.SYNCBUSY will be set and remain set until the transmitter
is enabled. When the transmitter is enabled, CTRLB.TXEN will read back as one.
Writing a one to CTRLB.TXEN when the USART is enabled will set STATUS.SYNCBUSY, which will remain set
until the receiver is enabled, and CTRLB.TXEN will read back as one.
This bit is not enable-protected.
z
Bits 15:14 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 13 – PMODE: Parity Mode
This bit selects the type of parity used when parity is enabled (CTRLA.FORM is one). The transmitter will automatically generate and send the parity of the transmitted data bits within each frame. The receiver will generate a
parity value for the incoming data and parity bit, compare it to the parity mode and, if a mismatch is detected, STATUS.PERR will be set.
0: Even parity.
1: Odd parity.
This bit is not synchronized.
z
Bit 12:10 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 9 – SFDE: Start of Frame Detection Enable
This bit controls whether the start-of-frame detector will wake up the device when a start bit is detected on the RxD
line, according to the table below.
This bit is not synchronized.
SFDE
INTENSET.RXS
INTENSET.RXC
Description
0
X
X
Start-of-frame detection disabled.
1
0
0
Reserved
1
0
1
Start-of-frame detection enabled. RXCIF wakes up the device from all sleep modes.
1
1
0
Start-of-frame detection enabled. RXSIF wakes up the device from all sleep modes.
1
1
1
Start-of-frame detection enabled. Both RXCIF and RXSIF wake up the device from
all sleep modes.
z
Bits 8:7 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 6 – SBMODE: Stop Bit Mode
This bit selects the number of stop bits transmitted.
0: One stop bit.
1: Two stop bits.
This bit is not synchronized.
z
Bits 5:3 – Reserved
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These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 2:0 – CHSIZE[2:0]: Character Size
These bits select the number of bits in a character.
These bits are not synchronized.
Table 24-8. Character Size
CHSIZE[2:0]
Description
0x0
8 bits
0x1
9 bits
0x2-0x4
Reserved
0x5
5 bits
0x6
6 bits
0x7
7 bits
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24.8.3 Debug Control
Name:
DBGCTRL
Offset:
0x08
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
DBGSTOP
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – DBGSTOP: Debug Stop Mode
This bit controls the baud-rate generator functionality when the CPU is halted by an external debugger.
0: The baud-rate generator continues normal operation when the CPU is halted by an external debugger.
1: The baud-rate generator is halted when the CPU is halted by an external debugger.
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24.8.4 Baud
Name:
BAUD
Offset:
0x0A
Reset:
0x0000
Property:
Enable-Protected, Write-Protected
Bit
15
14
13
12
11
10
9
8
BAUD[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
BAUD[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 15:0 – BAUD: Baud Value
These bits control the clock generation, as described in the SERCOM Baud Rate section.
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24.8.5 Interrupt Enable Clear
This register allows the user to disable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Set register (INTENSET).
Name:
INTENCLR
Offset:
0x0C
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
RXS
RXC
TXC
DRE
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 3 – RXS: Receive Start Interrupt Enable
0: Receive Start interrupt is disabled.
1: Receive Start interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Receive Start Interrupt Enable bit, which disables the Receive Start interrupt.
z
Bit 2 – RXC: Receive Complete Interrupt Enable
0: Receive Complete interrupt is disabled.
1: Receive Complete interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Receive Complete Interrupt Enable bit, which disables the Receive Complete
interrupt.
z
Bit 1 – TXC: Transmit Complete Interrupt Enable
0: Transmit Complete interrupt is disabled.
1: Transmit Complete interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Transmit Complete Interrupt Enable bit, which disables the Receive Complete
interrupt.
z
Bit 0 – DRE: Data Register Empty Interrupt Enable
0: Data Register Empty interrupt is disabled.
1: Data Register Empty interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Data Register Empty Interrupt Enable bit, which disables the Data Register
Empty interrupt.
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24.8.6 Interrupt Enable Set
This register allows the user to enable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Clear register (INTENCLR).
Name:
INTENSET
Offset:
0x0D
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
RXS
RXC
TXC
DRE
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 3 – RXS: Receive Start Interrupt Enable
0: Receive Start interrupt is disabled.
1: Receive Start interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Receive Start Interrupt Enable bit, which enables the Receive Start interrupt.
z
Bit 2 – RXC: Receive Complete Interrupt Enable
0: Receive Complete interrupt is disabled.
1: Receive Complete interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Receive Complete Interrupt Enable bit, which enables the Receive Complete
interrupt.
z
Bit 1– TXC: Transmit Complete Interrupt Enable
0: Transmit Complete interrupt is disabled.
1: Transmit Complete interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Transmit Complete Interrupt Enable bit, which enables the Transmit Complete
interrupt.
z
Bit 0 – DRE: Data Register Empty Interrupt Enable
0: Data Register Empty interrupt is disabled.
1: Data Register Empty interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Data Register Empty Interrupt Enable bit, which enables the Data Register
Empty interrupt.
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24.8.7 Interrupt Flag Status and Clear
Name:
INTFLAG
Offset:
0x0E
Reset:
0x00
Property:
Bit
7
6
5
4
3
2
1
0
RXS
RXC
TXC
DRE
Access
R
R
R
R
R/W
R
R/W
R
Reset
0
0
0
0
0
0
0
0
z
Bits 7:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 3 – RXS: Receive Start
This flag is cleared by writing a one to it.
This flag is set when a start condition is detected on the RxD line and start-of-frame detection is enabled
(CTRLB.SFDE is one).
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Receive Start interrupt flag.
z
Bit 2 – RXC: Receive Complete
This flag is cleared by reading the Data register (DATA) or by disabling the receiver.
This flag is set when there are unread data in DATA.
Writing a zero to this bit has no effect.
Writing a one to this bit has no effect.
z
Bit 1 – TXC: Transmit Complete
This flag is cleared by writing a one to it or by writing new data to DATA.
This flag is set when the entire frame in the transmit shift register has been shifted out and there are no new data
in DATA.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the flag.
z
Bit 0 – DRE: Data Register Empty
This flag is cleared by writing new data to DATA.
This flag is set when DATA is empty and ready to be written.
Writing a zero to this bit has no effect.
Writing a one to this bit has no effect.
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24.8.8 Status
Name:
STATUS
Offset:
0x10
Reset:
0x0000
Property:
Bit
15
14
13
12
11
10
9
8
R/W
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
BUFOVF
FERR
PERR
SYNCBUSY
Access
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bit 15 – SYNCBUSY: Synchronization Busy
This bit is cleared when the synchronization of registers between the clock domains is complete.
This bit is set when the synchronization of registers between clock domains is started.
z
Bits 14:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – BUFOVF: Buffer Overflow
Reading this bit before reading the Data register will indicate the error status of the next character to be read.
This bit is cleared by writing a one to the bit or by disabling the receiver.
This bit is set when a buffer overflow condition is detected. A buffer overflow occurs when the receive buffer is full,
there is a new character waiting in the receive shift register and a new start bit is detected.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear it.
z
Bit 1 – FERR: Frame Error
Reading this bit before reading the Data register will indicate the error status of the next character to be read.
This bit is cleared by writing a one to the bit or by disabling the receiver.
This bit is set if the received character had a frame error, i.e., when the first stop bit is zero.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear it.
z
Bit 0 – PERR: Parity Error
Reading this bit before reading the Data register will indicate the error status of the next character to be read.
This bit is cleared by writing a one to the bit or by disabling the receiver.
This bit is set if parity checking is enabled (CTRLA.FORM is one) and a parity error is detected.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear it.
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24.8.9 Data
Name:
DATA
Offset:
0x18
Reset:
0x0000
Property:
-
Bit
15
14
13
12
11
10
9
8
DATA[8]
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DATA[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 15:9 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 8:0 – DATA[8:0]: Data
Reading these bits will return the contents of the Receive Data register. The register should be read only when the
Receive Complete Interrupt Flag bit in the Interrupt Flag Status and Clear register (INTFLAG.RXC) is set. The status bits in STATUS should be read before reading the DATA value in order to get any corresponding error.
Writing these bits will write the Transmit Data register. This register should be written only when the Data Register
Empty Interrupt Flag bit in the Interrupt Flag Status and Clear register (INTFLAG.DRE) is set.
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25.
SERCOM SPI – SERCOM Serial Peripheral Interface
25.1
Overview
The serial peripheral interface (SPI) is one of the available modes in the Serial Communication Interface (SERCOM).
Refer to “SERCOM – Serial Communication Interface” on page 336 for details.
The SPI uses the SERCOM transmitter and receiver configured as shown in “Full-Duplex SPI Master Slave
Interconnection” on page 369. Each side, master and slave, depicts a separate SPI containing a shift register, a transmit
buffer and two receive buffers. In addition, the SPI master uses the SERCOM baud-rate generator, while the SPI slave
can use the SERCOM address match logic. Fields shown in capital letters are synchronous to CLK_SERCOMx_APB
and accessible by the CPU, while fields with lowercase letters are synchronous to the SCK clock.
25.2
Features
z Full-duplex, four-wire interface (MISO, MOSI, SCK, _SS)
z Single-buffered transmitter, double-buffered receiver
z Supports all four SPI modes of operation
z Single data direction operation allows alternate function on MISO or MOSI pin
z Selectable LSB- or MSB-first data transfer
z Master operation:
z
z
Serial clock speed up to half the system clock
8-bit clock generator
z Slave operation:
z
Serial clock speed up to the system clock
Optional 8-bit address match operation
z Operation in all sleep modes
z
25.3
Block Diagram
Figure 25-1. Full-Duplex SPI Master Slave Interconnection
Master
BAUD
Slave
Tx DATA
Tx DATA
ADDR/ADDRMASK
SCK
_SS
baud rate generator
MISO
shift register
shift register
MOSI
25.4
rx buffer
rx buffer
Rx DATA
Rx DATA
==
Address Match
Signal Description
Signal Name
Type
Description
PAD[3:0]
Digital I/O
General SERCOM pins
Refer to “I/O Multiplexing and Considerations” on page 16 for details on the pin mapping for this peripheral. One signal
can be mapped to one of several pins.
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25.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
25.5.1 I/O Lines
Using the SERCOM’s I/O lines requires the I/O pins to be configured using port configuration (PORT). Refer to “PORT”
on page 287 for details.
When the SERCOM is configured for SPI operation, the pins should be configured according to Table 25-1. If the
receiver is disabled, the data input pin can be used for other purposes. In master mode the slave select line (_SS) is
controlled by software.
Table 25-1. SPI Pin Configuration
Pin
Master SPI
Slave SPI
MOSI
Output
Input
MISO
Input
Output
SCK
Output
Input
_SS
User defined output enable
Input
The combined configuration of PORT and the Data In/Data Out and Data Out Pinout bit groups in Control A register will
define the physical position of the SPI signals in Table 25-1.
25.5.2 Power Management
The SPI can continue to operate in any sleep mode. The SPI interrupts can be used to wake up the device from sleep
modes. Refer to “PM – Power Manager” on page 107 for details on the different sleep modes.
25.5.3 Clocks
The SERCOM bus clock (CLK_SERCOMx_APB) can be enabled and disabled in the Power Manager, and the default
state of CLK_SERCOMx_APB can be found in the Peripheral Clock Masking section in the “PM – Power Manager” on
page 107.
A generic clock (GCLK_SERCOMx_CORE) is required to clock the SPI. This clock must be configured and enabled in
the Generic Clock Controller before using the SPI. Refer to “GCLK – Generic Clock Controller” on page 85 for details.
This generic clock is asynchronous to the bus clock (CLK_SERCOMx_APB). Due to this asynchronicity, writes to certain
registers will require synchronization between the clock domains. Refer to “Synchronization” on page 377 for further
details.
25.5.4 DMA
Not applicable.
25.5.5 Interrupts
The interrupt request line is connected to the Interrupt Controller. Using the SPI, interrupts requires the Interrupt
Controller to be configured first. Refer to “Nested Vector Interrupt Controller” on page 30 for details.
25.5.6 Events
Not applicable.
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25.5.7 Debug Operation
When the CPU is halted in debug mode, the SPI continues normal operation. If the SPI is configured in a way that
requires it to be periodically serviced by the CPU through interrupts or similar, improper operation or data loss may result
during debugging. The SPI can be forced to halt operation during debugging. Refer to the Debug Control (DBGCTRL)
register for details.
25.5.8 Register Access Protection
All registers with write-access are optionally write-protected by the Peripheral Access Controller (PAC), except the
following registers:
z
Interrupt Flag Clear and Status register (INTFLAG)
z
Status register (STATUS)
z
Data register (DATA)
Write-protection is denoted by the Write-Protection property in the register description.
When the CPU is halted in debug mode, all write-protection is automatically disabled.
Write-protection does not apply for accesses through an external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
25.5.9 Analog Connections
Not applicable.
25.6
Functional Description
25.6.1 Principle of Operation
The SPI is a high-speed synchronous data transfer interface. It allows fast communication between the device and
peripheral devices.
The SPI can operate as master or slave. As master, the SPI initiates and controls all data transactions. The SPI is single
buffered for transmitting and double buffered for receiving. When transmitting data, the Data register can be loaded with
the next character to be transmitted while the current transmission is in progress. For receiving, this means that the data
is transferred to the two-level receive buffer upon reception, and the receiver is ready for a new character.
The SPI transaction format is shown in Figure 25-2, where each transaction can contain one or more characters. The
character size is configurable, and can be either 8 or 9 bits.
Figure 25-2. SPI Transaction Format
Transaction
Character
MOSI/MISO
Character 0
Character 1
Character 2
_SS
The SPI master must initiate a transaction by pulling low the slave select line (_SS) of the desired slave. The master and
slave prepare data to be sent in their respective shift registers, and the master generates the serial clock on the SCK line.
Data are always shifted from master to slave on the master output, slave input line (MOSI), and from slave to master on
the master input, slave output line (MISO). The master signals the end of the transaction by pulling the _SS line high.
As each character is shifted out from the master, another character is shifted in from the slave.
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25.6.2 Basic Operation
25.6.2.1 Initialization
The following registers are enable-protected, meaning that they can only be written when the SPI is disabled
(CTRLA.ENABLE is zero):
z
Control A register (CTRLA), except Enable (CTRLA.ENABLE) and Software Reset (CTRLA.SWRST)
z
Control B register (CTRLB), except Receiver Enable (RXEN)
z
Baud register (BAUD)
z
Address register (ADDR)
Any writes to these registers when the SPI is enabled or is being enabled (CTRL.ENABLE is one) will be discarded.
Writes to these registers while the SPI is being disabled will be completed after the disabling is complete.
Enable-protection is denoted by the Enable-Protection property in the register description.
Before the SPI is enabled, it must be configured, as outlined by the following steps:
z
SPI mode in master or slave operation must be selected by writing 0x2 or 0x3 to the Operating Mode bit group in
the Control A register (CTRLA.MODE)
z
Transfer mode must be selected by writing the Clock Polarity bit and the Clock Phase bit in the Control A register
(CTRLA.CPOL and CTRLA.CPHA)
z
Transaction format must be selected by writing the Frame Format bit group in the Control A register
(CTRLA.FORM)
z
SERCOM pad to use for the receiver must be selected by writing the Data In Pinout bit in the Control A register
(CTRLA.DIPO)
z
SERCOM pads to use for the transmitter, slave select and serial clock must be selected by writing the Data Out
Pinout bit group in the Control A register (CTRLA.DOPO)
z
Character size must be selected by writing the Character Size bit in the Control B register (CTRLB.CHSIZE)
z
Data direction must be selected by writing the Data Order bit in the Control A register (CTRLA.DORD)
z
If the SPI is used in master mode, the Baud register (BAUD) must be written to generate the desired baud rate
z
The receiver can be enabled by writing a one to the Receiver Enable bit in the Control B register (CTRLB.RXEN)
25.6.2.2 Enabling, Disabling and Resetting
The SPI is enabled by writing a one to the Enable bit in the Control A register (CTRLA.ENABLE). The SPI is disabled by
writing a zero to CTRLA.ENABLE.
The SPI is reset by writing a one to the Software Reset bit in the Control A register (CTRLA.SWRST). All registers in the
SPI, except DBGCTRL, will be reset to their initial state, and the SPI will be disabled. Refer to CTRLA for details.
25.6.2.3 Clock Generation
In SPI master operation (CTRLA.MODE is 0x3), the serial clock (SCK) is generated internally using the SERCOM baudrate generator. When used in SPI mode, the baud-rate generator is set to synchronous mode, and the 8-bit Baud register
(BAUD) value is used to generate SCK, clocking the shift register. Refer to “Clock Generation – Baud-Rate Generator”
on page 339 for more details.
In SPI slave operation (CTRLA.MODE is 0x2), the clock is provided by an external master on the SCK pin. This clock is
used to directly clock the SPI shift register.
25.6.2.4 Data Register
The SPI Transmit Data register (TxDATA) and SPI Receive Data register (RxDATA) share the same I/O address,
referred to as the SPI Data register (DATA). Writing the DATA register will update the Transmit Data register. Reading
the DATA register will return the contents of the Receive Data register.
25.6.2.5 SPI Transfer Modes
There are four combinations of SCK phase and polarity with respect to the serial data. The SPI data transfer modes are
shown in Table 25-2 and Figure 25-3. SCK phase is selected by the Clock Phase bit in the Control A register
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(CTRLA.CPHA). SCK polarity is selected by the Clock Polarity bit in the Control A register (CTRLA.CPOL). Data bits are
shifted out and latched in on opposite edges of the SCK signal, ensuring sufficient time for the data signals to stabilize.
Table 25-2. SPI Transfer Modes
Mode
CPOL
CPHA
Leading Edge
Trailing Edge
0
0
0
Rising, sample
Falling, setup
1
0
1
Rising, setup
Falling, sample
2
1
0
Falling, sample
Rising, setup
3
1
1
Falling, setup
Rising, sample
Leading edge is the first clock edge in a clock cycle, while trailing edge is the second clock edge in a clock cycle.
Figure 25-3. SPI Transfer Modes
Mode 0
Mode 2
SAMPLE I
MOSI/MISO
CHANGE 0
MOSI PIN
CHANGE 0
MISO PIN
SS
MSB first (DORD = 0) MSB
LSB first (DORD = 1) LSB
Bit 6
Bit 1
Bit 5
Bit 2
Bit 4
Bit 3
Bit 3
Bit 4
Bit 2
Bit 5
Bit 1
Bit 6
LSB
MSB
Mode 1
Mode 3
SAMPLE I
MOSI/MISO
CHANGE 0
MOSI PIN
CHANGE 0
MISO PIN
SS
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25.6.2.6 Transferring Data
Master
When configured as a master (CTRLA.MODE is 0x3), the _SS line can be located at any general purpose I/O pin, and
must be configured as an output. When the SPI is ready for a data transaction, software must pull the _SS line low.
When writing a character to the Data register (DATA), the character will be transferred to the shift register when the shift
register is empty. Once the contents of TxDATA have been transferred to the shift register, the Data Register Empty flag
in the Interrupt Flag Status and Clear register (INTFLAG.DRE) is set, and a new character can be written to DATA.
As each character is shifted out from the master, another character is shifted in from the slave. If the receiver is enabled
(CTRLA.RXEN is one), the contents of the shift register will be transferred to the two-level receive buffer. The transfer
takes place in the same clock cycle as the last data bit is shifted in, and the Receive Complete Interrupt flag in the
Interrupt Flag Status and Clear register (INTFLAG.RXC) will be set. The received data can be retrieved by reading
DATA.
When the last character has been transmitted and there is no valid data in DATA, the Transmit Complete Interrupt flag in
the Interrupt Flag Status and Clear register (INTFLAG.TXC) is set. When the transaction is finished, the master must
indicate this to the slave by pulling the _SS line high.
Slave
When configured as a slave (CTRLA.MODE is 0x2), the SPI interface will remain inactive, with the MISO line tri-stated as
long as the _SS pin is pulled high. Software may update the contents of DATA at any time, as long as the Data Register
Empty flag in the Interrupt Status and Clear register (INTFLAG.DRE) is set.
When _SS is pulled low and SCK is running, the slave will sample and shift out data according to the transaction mode
set. When the contents of TxDATA have been loaded into the shift register, INTFLAG.DRE is set, and new data can be
written to DATA. Similar to the master, the slave will receive one character for each character transmitted. On the same
clock cycle as the last data bit of a character is received, the character will be transferred into the two-level receive buffer.
The received character can be retrieved from DATA when INTFLAG.RCX is set.
When the master pulls the _SS line high, the transaction is done and the Transmit Complete Interrupt flag in the Interrupt
Flag Status and Clear register (TXC) is set.
Once DATA is written, it takes up to three SCK clock cycles before the content of DATA is ready to be loaded into the
shift register. When the content of DATA is ready to be loaded, this will happen on the next character boundary. As a
consequence, the first character transferred in a SPI transaction will not be the content of DATA. This can be avoided by
using the preloading feature.
Refer to “Preloading of the Slave Shift Register” on page 375.
When transmitting several characters in one SPI transaction, the data has to be written to DATA while there are at least
three SCK clock cycles left in the current character transmission. If this criteria is not met, then the previous character
received will be transmitted.
After the DATA register is empty, it takes three CLK_SERCOM_APB cycles for INTFLAG.DRE to be set.
25.6.2.7 Receiver Error Bit
The SPI receiver has one error bit: the Buffer Overflow bit (BUFOVF), which can be read from the Status register
(STATUS). Upon error detection, the bit will be set until it is cleared by writing a one to it. The bit is also automatically
cleared when the receiver is disabled.
There are two methods for buffer overflow notification. When the immediate buffer overflow notification bit (CTRLA.IBON)
is set, STATUS.BUFOVF is raised immediately upon buffer overflow. Software can then empty the receive FIFO by
reading RxDATA until the receive complete interrupt flag (INTFLAG.RXC) goes low.
When CTRLA.IBON is zero, the buffer overflow condition travels with data through the receive FIFO. After the received
data is read, STATUS.BUFOVF will be set along with INTFLAG.RXC, and RxDATA will be zero.
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25.6.3 Additional Features
25.6.3.1 Address Recognition
When the SPI is configured for slave operation (CTRLA.MODE is 0x2) with address recognition (CTRLA.FORM is 0x2),
the SERCOM address recognition logic is enabled. When address recognition is enabled, the first character in a
transaction is checked for an address match. If there is a match, then the Receive Complete Interrupt flag in the Interrupt
Flag Status and Clear register (INTFLAG.RXC) is set, the MISO output is enabled and the transaction is processed. If
there is no match, the transaction is ignored.
If the device is in sleep mode, an address match can wake up the device in order to process the transaction. If the
address does not match, then the complete transaction is ignored. If a 9-bit frame format is selected, only the lower 8 bits
of the shift register are checked against the Address register (ADDR).
Refer to “Address Match and Mask” on page 342 for further details.
25.6.3.2 Preloading of the Slave Shift Register
When starting a transaction, the slave will first transmit the contents of the shift register before loading new data from
DATA. The first character sent can be either the reset value of the shift register (if this is the first transmission since the
last reset) or the last character in the previous transmission. Preloading can be used to preload data to the shift register
while _SS is high and eliminate sending a dummy character when starting a transaction.
In order to guarantee enough set-up time before the first SCK edge, enough time must be given between _SS going low
and the first SCK sampling edge, as shown in Figure 25-4.
Preloading is enabled by setting the Slave Data Preload Enable bit in the Control B register (CTRLB.PLOADEN).
Figure 25-4. Timing Using Preloading
Required _SS to SCK time using
PRELOADEN
_SS
_SS synchronized to
system domain
SCK
Synchronization to
system domain
MISO to SCK
setup time
Only one data character written to DATA will be preloaded into the shift register while the synchronized _SS signal (see
Figure 25-4) is high. The next character written to DATA before _SS is pulled low will be stored in DATA until transfer
begins. If the shift register is not preloaded, the current contents of the shift register will be shifted out.
25.6.3.3 Master with Several Slaves
If the bus consists of several SPI slaves, an SPI master can use general purpose I/O pins to control the _SS line to each
of the slaves on the bus, as shown in Figure 25-5. In this configuration, the single selected SPI slave will drive the tristate MISO line.
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Figure 25-5. Multiple Slaves in Parallel
shift register
SPI Master
MOSI
MISO
SCK
_SS[0]
MOSI
MISO
SCK
_SS
shift register
_SS[n-1]
MOSI
MISO
SCK
_SS
shift register
SPI Slave 0
SPI Slave n-1
An alternate configuration is shown in Figure 25-6. In this configuration, all n attached slaves are connected in series. A
common _SS line is provided to all slaves, enabling them simultaneously. The master must shift n characters for a
complete transaction.
Figure 25-6. Multiple Slaves in Series
shift register
SPI Master
MOSI
MISO
SCK
_SS
MOSI
MISO
SCK
_SS
shift register
MOSI
MISO
SCK
_SS
shift register
SPI Slave 0
SPI Slave n-1
25.6.3.4 Loop-back Mode
By configuring the Data In Pinout (CTRLA.DIPO) and Data Out Pinout (CTRLA.DOPO) to use the same data pins for
transmit and receive, loop-back is achieved. The loop-back is through the pad, so the signal is also available externally.
25.6.4 Interrupts
The SPI has the following interrupt sources:
z
Receive Complete (RXC): this is an asynchronous interrupt and can be used to wake-up the device from any sleep
mode.
z
Transmit Complete (TXC): this is an asynchronous interrupt and can be used to wake-up the device from any
sleep mode.
z
Data Register Empty (DRE): this is an asynchronous interrupt and can be used to wake-up the device from any
sleep mode.
Each interrupt source has an interrupt flag associated with it. The interrupt flag in the Interrupt Flag Status and Clear
register (INTFLAG) is set when the interrupt condition occurs. Each interrupt can be individually enabled by writing a one
to the corresponding bit in the Interrupt Enable Set register (INTENSET), and disabled by writing a one to the
corresponding bit in the Interrupt Enable Clear register (INTENCLR). An interrupt request is generated when the interrupt
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flag is set and the corresponding interrupt is enabled. The interrupt request remains active until the interrupt flag is
cleared, the interrupt is disabled or the SPI is reset. See the register description for details on how to clear interrupt flags.
The SPI has one common interrupt request line for all the interrupt sources. The user must read INTFLAG to determine
which interrupt condition is present.
Note that interrupts must be globally enabled for interrupt requests to be generated. Refer to “Nested Vector Interrupt
Controller” on page 30 for details.
For details on clearing interrupt flags, refer to INTFLAG.
25.6.5 Events
Not applicable.
25.6.6 Sleep Mode Operation
During master operation, the generic clock will continue to run in idle sleep mode. If the Run In Standby bit in the Control
A register (CTRLA.RUNSTDBY) is one, the GCLK_SERCOM_CORE will also be enabled in standby sleep mode. Any
interrupt can wake up the device.
If CTRLA.RUNSTDBY is zero during master operation, GLK_SERCOMx_CORE will be disabled when the ongoing
transaction is finished. Any interrupt can wake up the device.
During slave operation, writing a one to CTRLA.RUNSTDBY will allow the Receive Complete interrupt to wake up the
device.
If CTRLA.RUNSTDBY is zero during slave operation, all reception will be dropped, including the ongoing transaction.
25.6.7 Synchronization
Due to the asynchronicity between CLK_SERCOMx_APB and GCLK_SERCOMx_CORE, some registers must be
synchronized when accessed. A register can require:
z
Synchronization when written
z
Synchronization when read
z
Synchronization when written and read
z
No synchronization
When executing an operation that requires synchronization, the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set immediately, and cleared when synchronization is complete.
If an operation that requires synchronization is executed while STATUS.SYNCBUSY is one, the bus will be stalled. All
operations will complete successfully, but the CPU will be stalled and interrupts will be pending as long as the bus is
stalled.
The following bits need synchronization when written:
z
Software Reset bit in the Control A register (CTRLA.SWRST).
z
Enable bit in the Control A register (CTRLA.ENABLE).
z
Receiver Enable bit in the Control B register (CTRLB.RXEN).
CTRLB.RXEN behaves somewhat differently than described above. Refer to CTRLB register for details.
Write-synchronization is denoted by the Write-Synchronized property in the register description.
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25.7
Offset
Register Summary
Name
0x00
Bit Pos.
7:0
0x01
RUNSTDBY
MODE[2:0]
ENABLE
SWRST
IBON
15:8
CTRLA
DIPO[1:0]
0x02
23:16
0x03
31:24
DORD
0x04
7:0
PLOADEN
0x05
15:8
CPOL
DOPO[1:0]
CPHA
FORM[3:0]
CHSIZE[2:0]
AMODE[1:0]
CTRLB
0x06
23:16
0x07
31:24
RXEN
0x08
DBGCTRL
0x09
Reserved
0x0A
BAUD
0x0B
Reserved
0x0C
INTENCLR
7:0
RXC
TXC
DRE
0x0D
INTENSET
7:0
RXC
TXC
DRE
0x0E
INTFLAG
7:0
RXC
TXC
DRE
0x0F
Reserved
7:0
BUFOVF
0x10
7:0
DBGSTOP
7:0
BAUD[7:0]
STATUS
0x11
15:8
0x12
Reserved
0x13
Reserved
0x14
7:0
0x15
SYNCBUSY
ADDR[7:0]
15:8
ADDR
0x16
23:16
0x17
31:24
0x18
7:0
ADDRMASK[7:0]
DATA[7:0]
DATA
0x19
15:8
0x1A
Reserved
0x1B
Reserved
0x1C
Reserved
0x1D
Reserved
0x1E
Reserved
0x1F
Reserved
DATA[8]
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25.8
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-Protected property in each individual register description. Refer to “Register Access Protection” on page 371
for details.
Some registers require synchronization when read and/or written. Write-synchronization is denoted by the WriteSynchronized property in each individual register description. Refer to “Synchronization” on page 377 for details.
Some registers are enable-protected, meaning they can only be written when the USART is disabled. Enable-protection
is denoted by the Enable-Protected property in each individual register description.
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25.8.1 Control A
Name:
CTRLA
Offset:
0x00
Reset:
0x00000000
Property:
Write-Protected, Enable-Protected, Write-Synchronized
Bit
31
30
29
28
DORD
CPOL
CPHA
27
26
25
24
FORM[3:0]
Access
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
DIPO[1:0]
DOPO[1:0]
Access
R
R
R/W
R/W
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
IBON
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ENABLE
SWRST
RUNSTDBY
Access
Reset
MODE[2:0]
R/W
R
R
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bit 31 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 30 – DORD: Data Order
This bit indicates the data order when a character is shifted out from the Data register.
0: MSB is transferred first.
1: LSB is transferred first.
This bit is not synchronized.
z
Bit 29 – CPOL: Clock Polarity
In combination with the Clock Phase bit (CPHA), this bit determines the SPI transfer mode.
0: SCK is low when idle. The leading edge of a clock cycle is a rising edge, while the trailing edge is a falling edge.
1: SCK is high when idle. The leading edge of a clock cycle is a falling edge, while the trailing edge is a rising edge.
This bit is not synchronized.
z
Bit 28 – CPHA: Clock Phase
In combination with the Clock Polarity bit (CPOL), this bit determines the SPI transfer mode.
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0: The data is sampled on a leading SCK edge and changed on a trailing SCK edge.
1: The data is sampled on a trailing SCK edge and changed on a leading SCK edge.
This bit is not synchronized.
Table 25-3. SPI Transfer Modes
Mode
CPOL
CPHA
Leading Edge
Trailing Edge
0x0
0
0
Rising, sample
Falling, change
0x1
0
1
Rising, change
Falling, sample
0x2
1
0
Falling, sample
Rising, change
0x3
1
1
Falling, change
Rising, sample
z
Bits 27:24 – FORM[3:0]: Frame Format
Table 25-4 shows the various frame formats supported by the SPI. When a frame format with address is selected,
the first byte received is checked against the ADDR register.
Table 25-4. Frame Format
FORM[3:0]
Name
Description
0x0
SPI
SPI frame
0x1
-
Reserved
0x2
SPI_ADDR
SPI frame with address
0x3-0xF
-
Reserved
z
Bits 23:22 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 21:20 – DIPO[1:0]: Data In Pinout
These bits define the data in (DI) pad configurations.
In master operation, DI is MISO.
In slave operation, DI is MOSI.
These bits are not synchronized.
Table 25-5. Data In Pinout
DIPO[1:0]
Name
Description
0x0
PAD[0]
SERCOM PAD[0] is used as data input
0x1
PAD[1]
SERCOM PAD[1] is used as data input
0x2
PAD[2]
SERCOM PAD[2] is used as data input
0x3
PAD[3]
SERCOM PAD[3] is used as data input
z
Bits 19:18 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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z
Bit 17:16 – DOPO: Data Out Pinout
This bit defines the available pad configurations for data out (DO) and the serial clock (SCK). In slave operation,
the slave select line (_SS) is controlled by DOPO, while in master operation the _SS line is controlled by the port
configuration.
In master operation, DO is MOSI.
In slave operation, DO is MISO.
These bits are not synchronized.
Table 25-6. Data Out Pinout
DOPO
DO
SCK
Slave _SS
Master _SS
0x0
PAD[0]
PAD[1]
PAD[2]
System configuration
0x1
PAD[2]
PAD[3]
PAD[1]
System configuration
0x2
PAD[3]
PAD[1]
PAD[2]
System configuration
0x3
PAD[0]
PAD[3]
PAD[1]
System configuration
z
Bits 15:9 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 8 – IBON: Immediate Buffer Overflow Notification
This bit controls when the buffer overflow status bit (STATUS.BUFOVF) is asserted when a buffer overflow occurs.
0: STATUS.BUFOVF is asserted when it occurs in the data stream.
1: STATUS.BUFOVF is asserted immediately upon buffer overflow.
This bit is not synchronized.
z
Bit 7 – RUNSTDBY: Run In Standby
This bit defines the functionality in standby sleep mode.
These bits are not synchronized.
Table 25-7. Run In Standby Configuration
RUNSTDBY
Slave
Master
0x0
Disabled. All reception is dropped,
including the ongoing transaction.
Generic clock is disabled when ongoing transaction is
finished. All interrupts can wake up the device.
0x1
Wake on Receive Complete interrupt.
Generic clock is enabled while in sleep modes. All
interrupts can wake up the device.
z
Bits 6:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 4:2 – MODE: Operating Mode
These bits must be written to 0x2 or 0x3 to select the SPI serial communication interface of the SERCOM.
0x2: SPI slave operation
0x3: SPI master operation
These bits are not synchronized.
z
Bit 1 – ENABLE: Enable
0: The peripheral is disabled or being disabled.
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1: The peripheral is enabled or being enabled.
Due to synchronization, there is delay from writing CTRLA.ENABLE until the peripheral is enabled/disabled. The
value written to CTRL.ENABLE will read back immediately and the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set. STATUS.SYNCBUSY is cleared when the operation is complete.
This bit is not enable-protected.
z
Bit 0 – SWRST: Software Reset
0: There is no reset operation ongoing.
1: The reset operation is ongoing.
Writing a zero to this bit has no effect.
Writing a one to this bit resets all registers in the SERCOM, except DBGCTRL, to their initial state, and the SERCOM will be disabled.
Writing a one to CTRL.SWRST will always take precedence, meaning that all other writes in the same write-operation will be discarded.
Due to synchronization, there is a delay from writing CTRLA.SWRST until the reset is complete. CTRLA.SWRST
and STATUS.SYNCBUSY will both be cleared when the reset is complete.
This bit is not enable-protected.
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25.8.2 Control B
Name:
CTRLB
Offset:
0x04
Reset:
0x00000000
Property:
Write-Protected, Enable-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
RXEN
Access
R
R
R
R
R
R
R/W
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
R/W
R/W
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
AMODE[1:0]
Access
PLOADEN
CHSIZE[2:0]
Access
R
R/W
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 31:18 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 17 – RXEN: Receiver Enable
0: The receiver is disabled or being enabled.
1: The receiver is enabled or it will be enabled when SPI is enabled.
Writing a zero to this bit will disable the SPI receiver immediately. The receive buffer will be flushed, data from
ongoing receptions will be lost and STATUS.BUFOVF will be cleared.
Writing a one to CTRLB.RXEN when the SPI is disabled will set CTRLB.RXEN immediately. When the SPI is
enabled, CTRLB.RXEN will be cleared, STATUS.SYNCBUSY will be set and remain set until the receiver is
enabled. When the receiver is enabled CTRLB.RXEN will read back as one.
Writing a one to CTRLB.RXEN when the SPI is enabled will set STATUS.SYNCBUSY, which will remain set until
the receiver is enabled, and CTRLB.RXEN will read back as one.
This bit is not enable-protected.
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z
Bit 16 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 15:14 – AMODE: Address Mode
These bits set the slave addressing mode when the frame format (CTRLA.FORM) with address is used. They are
unused in master mode.
Table 25-8. Address Mode
AMODE[1:0]
Name
Description
0x0
MASK
ADDRMASK is used as a mask to the ADDR register
0x1
2_ADDRS
The slave responds to the two unique addresses in ADDR and ADDRMASK
0x2
RANGE
The slave responds to the range of addresses between and including ADDR
and ADDRMASK. ADDR is the upper limit
0x3
Reserved
z
Bits 13:7 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 6 – PLOADEN: Slave Data Preload Enable
Setting this bit will enable preloading of the slave shift register when there is no transfer in progress. If the _SS line
is high when DATA is written, it will be transferred immediately to the shift register.
z
Bits 5:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 2:0 – CHSIZE[2:0]: Character Size
Table 25-9. Character Size
CHSIZE[2:0]
Name
Description
0x0
8BIT
8 bits
0x1
9BIT
9 bits
0x2-0x7
Reserved
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25.8.3
Debug Control
Name:
DBGCTRL
Offset:
0x08
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
DBGSTOP
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – DBGSTOP: Debug Stop Mode
This bit controls the functionality when the CPU is halted by an external debugger.
0: The baud-rate generator continues normal operation when the CPU is halted by an external debugger.
1: The baud-rate generator is halted when the CPU is halted by an external debugger.
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25.8.4 Baud Rate
Name:
BAUD
Offset:
0x0A
Reset:
0x00
Property:
Write-Protected, Enable-Protected
Bit
7
6
5
4
3
2
1
0
BAUD[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 7:0 – BAUD: Baud Register
These bits control the clock generation, as described in the SERCOM “Clock Generation – Baud-Rate Generator”
on page 339.
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25.8.5
Interrupt Enable Clear
This register allows the user to disable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Set register (INTENSET).
Name:
INTENCLR
Offset:
0x0C
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
RXC
TXC
DRE
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – RXC: Receive Complete Interrupt Enable
0: Receive Complete interrupt is disabled.
1: Receive Complete interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Receive Complete Interrupt Enable bit, which disables the Receive Complete
interrupt.
z
Bit 1 – TXC: Transmit Complete Interrupt Enable
0: Transmit Complete interrupt is disabled.
1: Transmit Complete interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Transmit Complete Interrupt Enable bit, which disable the Transmit Complete
interrupt.
z
Bit 0 – DRE: Data Register Empty Interrupt Enable
0: Data Register Empty interrupt is disabled.
1: Data Register Empty interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Data Register Empty Interrupt Enable bit, which disables the Data Register
Empty interrupt.
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25.8.6 Interrupt Enable Set
This register allows the user to disable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Clear register (INTENCLR).
Name:
INTENSET
Offset:
0x0D
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
RXC
TXC
DRE
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – RXC: Receive Complete Interrupt Enable
0: Receive Complete interrupt is disabled.
1: Receive Complete interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Receive Complete Interrupt Enable bit, which enables the Receive Complete
interrupt.
z
Bit 1 – TXC: Transmit Complete Interrupt Enable
0: Transmit Complete interrupt is disabled.
1: Transmit Complete interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Transmit Complete Interrupt Enable bit, which enables the Transmit Complete
interrupt.
z
Bit 0 – DRE: Data Register Empty Interrupt Enable
0: Data Register Empty interrupt is disabled.
1: Data Register Empty interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Data Register Empty Interrupt Enable bit, which enables the Data Register
Empty interrupt.
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25.8.7 Interrupt Flag Status and Clear
Name:
INTFLAG
Offset:
0x0E
Reset:
0x00
Property:
-
Bit
7
6
5
4
3
2
1
0
RXC
TXC
DRE
Access
R
R
R
R
R
R
R/W
R
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – RXC: Receive Complete
This flag is cleared by reading the Data (DATA) register or by disabling the receiver.
This flag is set when there are unread data in the receive buffer. If address matching is enabled, the first data
received in a transaction will be an address.
Writing a zero to this bit has no effect.
Writing a one to this bit has no effect.
z
Bit 1 – TXC: Transmit Complete
This flag is cleared by writing a one to it or by writing new data to DATA.
In master mode, this flag is set when the data have been shifted out and there are no new data in DATA.
In slave mode, this flag is set when the _SS pin is pulled high. If address matching is enabled, this flag is only set
if the transaction was initiated with an address match.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the flag.
z
Bit 0 – DRE: Data Register Empty
This flag is cleared by writing new data to DATA.
This flag is set when DATA is empty and ready for new data to transmit.
Writing a zero to this bit has no effect.
Writing a one to this bit has no effect.
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25.8.8 Status
Name:
STATUS
Offset:
0x10
Reset:
0x0000
Property:
–
Bit
15
14
13
12
11
10
9
8
SYNCBUSY
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
BUFOVF
Access
R
R
R
R
R
R/W
R
R
Reset
0
0
0
0
0
0
0
0
z
Bit 15 – SYNCBUSY: Synchronization Busy
This bit is cleared when the synchronization of registers between the clock domains is complete.
This bit is set when the synchronization of registers between clock domains is in progress.
z
Bits 14:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – BUFOVF: Buffer Overflow
Reading this bit before reading DATA will indicate the error status of the next character to be read.
This bit is cleared by writing a one to the bit or by disabling the receiver.
This bit is set when a buffer overflow condition is detected. An overflow condition occurs if the two-level receive
buffer is full when the last bit of the incoming character is shifted into the shift register. All characters shifted into
the shift registers before the overflow condition is eliminated by reading DATA will be lost.
When set, the corresponding RxDATA will be 0.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear it.
z
Bits 1:0 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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25.8.9
Address
Name:
ADDR
Offset:
0x14
Reset:
0x00000000
Property:
Write-Protected, Enable-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
ADDRMASK[7:0]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ADDR[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 31:24 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 23:16 – ADDRMASK[7:0]: Address Mask
These bits hold the address mask when the transaction format (CTRLA.FORM) with address is used.
z
Bits 15:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 7:0 – ADDR[7:0]: Address
These bits hold the address when the transaction format (CTRLA.FORM) with address is used.
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25.8.10 Data
Name:
DATA
Offset:
0x18
Reset:
0x0000
Property:
–
Bit
15
14
13
12
11
10
9
8
DATA[8]
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DATA[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 15:9 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 8:0 – DATA[8:0]: Data
Reading these bits will return the contents of the receive data buffer. The register should be read only when the
Receive Complete Interrupt Flag bit in the Interrupt Flag Status and Clear register (INTFLAG.RXC) is set.
Writing these bits will write the transmit data buffer. This register should be written only when the Data Register
Empty Interrupt Flag bit in the Interrupt Flag Status and Clear register (INTFLAG.DRE) is set.
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26.
SERCOM I2C – SERCOM Inter-Integrated Circuit
26.1
Overview
The inter-integrated circuit (I2C) interface is one of the available modes in the serial communication interface (SERCOM).
Refer to “SERCOM – Serial Communication Interface” on page 336 for details.
The I2C interface uses the SERCOM transmitter and receiver configured as shown in Figure 26-1. Fields shown in capital
letters are registers accessible by the CPU, while lowercase fields are internal to the SERCOM. Each side, master and
slave, depicts a separate I2C interface containing a shift register, a transmit buffer and a receive buffer. In addition, the
I2C master uses the SERCOM baud-rate generator, while the I2C slave uses the SERCOM address match logic.
26.2
Features
z Master or slave operation
z Philips I2C compatible
z SMBus™ compatible
z 100kHz and 400kHz support at low system clock frequencies
z Physical interface includes:
z
z
Slew-rate limited outputs
Filtered inputs
z Slave operation:
z
Operation in all sleep modes
Wake-up on address match
z Address match in hardware for:
z 7-bit unique address and/or 7-bit general call address
z 7-bit address range
z Two unique 7-bit addresses
z
26.3
Block Diagram
Figure 26-1. I2C Single-Master Single-Slave Interconnection
Master
BAUD
Slave
Tx DATA
Tx DATA
0
SCL
ADDR/ADDRMASK
0
baud rate generator
SCL low hold
shift register
shift register
0
Rx DATA
SDA
0
Rx DATA
==
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26.4
Signal Description
Signal Name
Type
Description
PAD[0]
Digital I/O
SDA
PAD[1]
Digital I/O
SCL
PAD[2]
Digital I/O
SDA_OUT (4-wire)
PAD[3]
Digital I/O
SDC_OUT (4-wire)
Refer to “I/O Multiplexing and Considerations” on page 16 for details on the pin mapping for this peripheral. One signal
can be mapped on several pins. Note that not all the pins are I2C pins. Refer to Table 5-1 for details on the pin type for
each pin.
26.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
26.5.1 I/O Lines
Using the SERCOM’s I/O lines requires the I/O pins to be configured. Refer to “PORT” on page 287 for details.
26.5.2 Power Management
The I2C will continue to operate in any sleep mode where the selected source clock is running. I2C interrupts can be used
to wake up the device from sleep modes. The events can trigger other operations in the system without exiting sleep
modes. Refer to “PM – Power Manager” on page 107 for details on the different sleep modes.
26.5.3 Clocks
The SERCOM bus clock (CLK_SERCOMx_APB, where i represents the specific SERCOM instance number) is enabled
by default, and can be enabled and disabled in the Power Manager. Refer to “PM – Power Manager” on page 107 for
details.
The SERCOM bus clock (CLK_SERCOMx_APB) is enabled by default, and can be enabled and disabled in the Power
Manager. Refer to “PM – Power Manager” on page 107 for details.
Two generic clocks are used by the SERCOM (GCLK_SERCOMx_CORE and GCLK_SERCOM_SLOW). The core clock
(GCLK_SERCOMx_CORE) is required to clock the SERCOM while operating as a master, while the slow clock
(GCLK_SERCOM_SLOW) is required only for certain functions. These clocks must be configured and enabled in the
Generic Clock Controller (GCLK) before using the SERCOM. Refer to “GCLK – Generic Clock Controller” on page 85 for
details.
These generic clocks are asynchronous to the SERCOM bus clock (CLK_SERCOMx_APB). Due to this asynchronicity,
writes to certain registers will require synchronization between the clock domains. Refer to the “Synchronization” on page
407 section for further details.
26.5.4 DMA
Not applicable.
26.5.5 Interrupts
The interrupt request line is connected to the Interrupt Controller. Using the I2C interrupts requires the Interrupt Controller
to be configured first. Refer to “Nested Vector Interrupt Controller” on page 30 for details.
26.5.6 Events
Not applicable.
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26.5.7 Debug Operation
When the CPU is halted in debug mode, the I2C interface continues normal operation. If the I2C interface is configured in
a way that requires it to be periodically serviced by the CPU through interrupts or similar, improper operation or data loss
may result during debugging. The I2C interface can be forced to halt operation during debugging.
Refer to the DBGCTRL register for details.
26.5.8 Register Access Protection
All registers with write-access are optionally write-protected by the Peripheral Access Controller (PAC), except the
following registers:
z
Interrupt Flag Status and Clear register (INTFLAG
z
Status register (STATUS)
z
Address register (ADDR)
z
Data register (DATA)
Write-protection is denoted by the Write-Protected property in the register description.
Write-protection does not apply to accesses through en external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
26.5.9 Analog Connections
Not applicable.
26.6
Functional Description
26.6.1 Principle of Operation
The I2C interface uses two physical lines for communication:
z
Serial Data Line (SDA) for packet transfer
z
Serial Clock Line (SCL) for the bus clock
A transaction starts with the start condition, followed by a 7-bit address and a direction bit (read or write) sent from the I2C
master. The addressed I2C slave will then acknowledge (ACK) the address, and data packet transactions can
commence. Every 9-bit data packet consists of 8 data bits followed by a one-bit reply indicating whether the data was
acknowledged or not. In the event that a data packet is not acknowledged (NACK), whether sent from the I2C slave or
master, it will be up to the I2C master to either terminate the connection by issuing the stop condition, or send a repeated
start if more data is to be transceived.
Figure 26-2 illustrates the possible transaction formats and Figure 26-3 explains the legend used.
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Figure 26-2. Basic I2C Transaction Diagram
SDA
SCL
6 ... 0
S
ADDRESS
S
7 ... 0
R/W
ADDRESS
ACK
R/W A
7 ... 0
DATA
ACK
DATA
A
DATA
P
ACK/NACK
DATA
A/A
P
Direction
Address Packet
Data Packet #0
Data Packet #1
Transaction
Figure 26-3. Transaction Diagram Syntax
Bus Driver:
Master Drives Bus
S
START Condition
Slave Drives Bus
Sr
Repeated START Condition
Either Master or Slave
Drives Bus
P
STOP Condition
Data Packet Direction:
R
Master Read
"1"
W
Special Bus Conditions
Acknowledge:
A
Acknowledge (ACK)
"0"
Master Write
"0"
A
Not Acknowledge (NACK)
"1"
26.6.2 Basic Operation
26.6.2.1 Initialization
The following registers are enable-protected, meaning they can be written only when the I2C interface is disabled
(CTRLA.ENABLE is zero):
z
Control A register (CTRLA), except Enable (CTRLA.ENABLE) and Software Reset (CTRLA.SWRST)
z
Control B register (CTRLB), except Acknowledge Action (CTRLB.ACKACT) and Command (CTRLB.CMD)
z
Baud Rate register (BAUD)
z
Address register (ADDR) while in slave operation
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Any writes to these bits or registers when the I2C interface is enabled or is being enabled (CTRLA.ENABLE is one) will
be discarded. Writes to these registers while the I2C interface is being disabled will be completed after the disabling is
complete.
Enable-protection is denoted by the Enable-Protection property in the register description.
Before the I2C interface is enabled, it must be configured as outlined by the following steps:
I2C mode in master or slave operation must be selected by writing 0x4 or 0x5 to the Operating Mode bit group in the
Control A register (CTRLA.MODE)
z
SCL low time-out can be enabled by writing to the SCL Low Time-Out bit in the Control A register
(CTRLA.LOWTOUT)
z
In master operation, the inactive bus time-out can be set in the Inactive Time-Out bit group in the Control A register
(CTRLA.INACTOUT)
z
Hold time for SDA can be set in the SDA Hold Time bit group in the Control A register (CTRLA.SDAHOLD)
z
Smart operation can be enabled by writing to the Smart Mode Enable bit in the Control B register (CTRLB.SMEN)
z
In slave operation, the address match configuration must be set in the Address Mode bit group in the Control B
register (CTRLB.AMODE)
z
In slave operation, the addresses must be set, according to the selected address configuration, in the Address and
Address Mask bit groups in the Address register (ADDR.ADDR and ADDR.ADDRMASK)
z
In master operation, the Baud Rate register (BAUD) must be written to generate the desired baud rate
26.6.2.2 Enabling, Disabling and Resetting
The I2C interface is enabled by writing a one to the Enable bit in the Control A register (CTRLA.ENABLE). The I2C
interface is disabled by writing a zero to CTRLA.ENABLE. The I2C interface is reset by writing a one to the Software
Reset bit in the Control A register (CTRLA.SWRST). All registers in the I2C interface, except DBGCTRL, will be reset to
their initial state, and the I2C interface will be disabled. Refer to CTRLA for details.
26.6.2.3 I2C Bus State Logic
The bus state logic includes several logic blocks that continuously monitor the activity on the I2C bus lines in all sleep
modes. The start and stop detectors and the bit counter are all essential in the process of determining the current bus
state. The bus state is determined according to the state diagram shown in Figure 26-4. Software can get the current bus
state by reading the Master Bus State bits in the Status register (STATUS.BUSSTATE). The value of
STATUS.BUSSTATE in the figure is shown in binary.
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Figure 26-4. Bus State Diagram
RESET
UNKNOWN
(0b00)
P + Timeout
Sr
S
IDLE
(0b01)
BUSY
(0b11)
P + Timeout
Command P
Write ADDR
(S)
Arbitration
Lost
OWNER
(0b10)
Write ADDR(Sr)
The bus state machine is active when the I2C master is enabled. After the I2C master has been enabled, the bus state is
unknown. From the unknown state, the bus state machine can be forced to enter the idle state by writing to
STATUS.BUSSTATE accordingly. However, if no action is taken by software, the bus state will become idle if a stop
condition is detected on the bus. If the inactive bus time-out is enabled, the bus state will change from unknown to idle on
the occurrence of a time-out. Note that after a known bus state is established, the bus state logic will not re-enter the
unknown state from either of the other states.
When the bus is idle it is ready for a new transaction. If a start condition is issued on the bus by another I2C master in a
multimaster setup, the bus becomes busy until a stop condition is detected. The stop condition will cause the bus to reenter the IDLE state. If the inactive bus time-out (SMBus) is enabled, the bus state will change from busy to idle on the
occurrence of a time-out. If a start condition is generated internally by writing the Address bit group in the Address
register (ADDR.ADDR) while in idle state, the owner state is entered. If the complete transaction was performed without
interference, i.e., arbitration not lost, the I2C master is allowed to issue a stop condition, which in turn will cause a change
of the bus state back to idle. However, if a packet collision is detected when in the owner state, the arbitration is assumed
lost and the bus state becomes busy until a stop condition is detected.
A repeated start condition will change the bus state only if arbitration is lost while issuing a repeated start.
26.6.2.4 Clock Generation
The Master I2C clock (SCL) frequency is determined by a number of factors. The low (TLOW) and high (T_HIGH) times are
determined by the Baud Rate register (BAUD), while the rise (TRISE) and fall (TFALL) times are determined by the bus
topology. Because of the wired-AND logic of the bus, TFALL will be considered as part of TLOW. Likewise, TRISE will be in a
state between TLOW and THIGH until a high state has been detected.
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Figure 26-5. SCL Timing
TRISE
P
TLOW
S
Sr
SCL
THIGH
TBUF
TFALL
SDA
THD;STA
TSU;STO
TSU;STA
The following parameters are timed using the SCL low time period. This comes from the Master Baud Rate Low bit group
in the Baud Rate register (BAUD.BAUDLOW) when non-zero, or the Master Baud Rate bit group in the Baud Rate
register (BAUD.BAUD) when BAUD.BAUDLOW is zero.
z
TLOW – Low period of SCL clock
z
TSU;STO – Set-up time for stop condition
z
TBUF – Bus free time between stop and start conditions
z
THD;STA – Hold time (repeated) start condition
z
TSU;STA – Set-up time for repeated start condition
z
THIGH is timed using the SCL high time count from BAUD.BAUD
z
TRISE is determined by the bus impedance; for internal pull-ups. Refer to “Electrical Characteristics” on page
571 for details.
z
TFALL is determined by the open-drain current limit and bus impedance; can typically be regarded as zero.
Refer to “Electrical Characteristics” on page 571 for details.
The SCL frequency is given by:
f
SCL
=
1
TLOW + THIGH + TRISE
When BAUD.BAUDLOW is zero, the BAUD.BAUD value is used to time both SCL high and SCL low. In this case the
following formula will give the SCL frequency:
f
SCL
=
f
GCLK
2(5 + BAUD) +
f
GCLK
TRISE
When BAUD.BAUDLOW is non-zero, the following formula is used to determine the SCL frequency:
f
SCL
=
f
GCLK
10 + BAUD + BAUDLOW +
f
GCLK
TRISE
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When BAUDLOW is non-zero, the following formula can be used to determine the SCL frequency:
f
SCL
=
f
GCLK
10 + BAUD + BAUDLOW +
f
GCLK
TRISE
The following formulas can be used to determine the SCL TLOW and THIGH times:
=
T
low
T
HIGH
BAUD.BAUDLOW + 5
f GCLK
=
BAUD.BAUD + 5
f GCLK
26.6.2.5 I2C Master Operation
The I2C master is byte-oriented and interrupt based. The number of interrupts generated is kept at a minimum by
automatic handling of most events. Auto-triggering of operations and a special smart mode, which can be enabled by
writing a one to the Smart Mode Enable bit in the Control A register (CTRLA.SMEN), are included to reduce software
driver complexity and code size.
The I2C master operates according to the behavior diagram shown in Figure 26-6. The circles with a capital letter M
followed by a number (M1, M2... etc.) indicate which node in the figure the bus logic can jump to based on software or
hardware interaction.
This diagram is used as reference for the description of the I2C master operation throughout the document.
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Figure 26-6. I2C Master Behavioral Diagram
APPLICATION
MASTER WRITE INTERRUPT + HOLD
M1
M2
BUSY
S
W
P
M3
IDLE
S
Wait for
IDLE
M4
ADDRESS
R/W BUSY
S
W
R/W A
S
W
P
S
W
Sr
W
A
M1
BUSY
M2
IDLE
M3
S
W
BUSY
DATA
M4
A/A
MASTER READ INTERRUPT+ HOLD
S
W
S
W
Software interaction
A
BUSY
The master provides data
on the bus
A/A
Addressed slave provides
data on the bus
A/A Sr
P
IDLE
M4
M2
M3
A/A
R
A
DATA
Transmitting Address Packets
The I2C master starts a bus transaction by writing ADDR.ADDR with the I2C slave address and the direction bit. If the bus
is busy, the I2C master will wait until the bus becomes idle before continuing the operation. When the bus is idle, the I2C
master will issue a start condition on the bus. The I2C master will then transmit an address packet using the address
written to ADDR.ADDR.
After the address packet has been transmitted by the I2C master, one of four cases will arise, based on arbitration and
transfer direction.
Case 1: Arbitration lost or bus error during address packet transmission
If arbitration was lost during transmission of the address packet, the Master on Bus bit in the Interrupt Flag register
(INTFLAG.MB) and the Arbitration Lost bit in the Status register (STATUS.ARBLOST) are both set. Serial data output to
SDA is disabled, and the SCL is released, which disables clock stretching. In effect the I2C master is no longer allowed to
perform any operation on the bus until the bus is idle again. A bus error will behave similarly to the arbitration lost
condition. In this case, the MB interrupt flag and Master Bus Error bit in the Status register (STATUS.BUSERR) are both
set in addition to STATUS.ARBLOST.
The Master Received Not Acknowledge bit in the Status register (STATUS.RXNACK) will always contain the last
successfully received acknowledge or not acknowledge indication.
In this case, software will typically inform the application code of the condition and then clear the interrupt flag before
exiting the interrupt routine. No other flags have to be cleared at this point, because all flags will be cleared automatically
the next time the ADDR.ADDR register is written.
Case 2: Address packet transmit complete – No ACK received
If no I2C slave device responds to the address packet, then the INTFLAG.MB interrupt flag is set and STATUS.RXNACK
is set. The clock hold is active at this point, preventing further activity on the bus.
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The missing ACK response can indicate that the I2C slave is busy with other tasks or sleeping and, therefore, not able to
respond. In this event, the next step can be either issuing a stop condition (recommended) or resending the address
packet by using a repeated start condition. However, the reason for the missing acknowledge can be that an invalid I2C
slave address has been used or that the I2C slave is for some reason disconnected or faulty. If using SMBus logic, the
slave must ACK the address, and hence no action means the slave is not available on the bus.
Case 3: Address packet transmit complete – Write packet, Master on Bus set
If the I2C master receives an acknowledge response from the I2C slave, INTFLAG.MB is set and STATUS.RXNACK is
cleared. The clock hold is active at this point, preventing further activity on the bus.
In this case, the software implementation becomes highly protocol dependent. Three possible actions can enable the I2C
operation to continue. The three options are:
z
The data transmit operation is initiated by writing the data byte to be transmitted into DATA.DATA.
z
Transmit a new address packet by writing ADDR.ADDR. A repeated start condition will automatically be
inserted before the address packet.
z
Issue a stop condition, consequently terminating the transaction.
Case 4: Address packet transmit complete – Read packet, Slave on Bus set
If the I2C master receives an ACK from the I2C slave, the I2C master proceeds to receive the next byte of data from the
I2C slave. When the first data byte is received, the Slave on Bus bit in the Interrupt Flag register (INTFLAG.SB) is set and
STATUS.RXNACK is cleared. The clock hold is active at this point, preventing further activity on the bus.
In this case, the software implementation becomes highly protocol dependent. Three possible actions can enable the I2C
operation to continue. The three options are:
z
Let the I2C master continue to read data by first acknowledging the data received. This is automatically done
when reading DATA.DATA if the smart mode is enabled.
z
Transmit a new address packet.
z
Terminate the transaction by issuing a stop condition.
An ACK or NACK will be automatically transmitted for the last two alternatives if smart mode is enabled. The
Acknowledge Action bit in the Control B register (CTRLB.ACKACT) determines whether ACK or NACK should be sent.
Transmitting Data Packets
When an address packet with direction set to write (STATUS.DIR is zero) has been successfully transmitted,
INTFLAG.MB will be set and the I2C master can start transmitting data by writing to DATA.DATA. The I2C master
transmits data via the I2C bus while continuously monitoring for packet collisions. If a collision is detected, the I2C master
looses arbitration and STATUS.ARBLOST is set. If the transmit was successful, the I2C master automatically receives an
ACK bit from the I2C slave and STATUS.RXNACK will be cleared. INTFLAG.MB will be set in both cases, regardless of
arbitration outcome.
Testing STATUS.ARBLOST and handling the arbitration lost condition in the beginning of the I2C Master on Bus interrupt
is recommended. This can be done, as there is no difference between handling address and data packet arbitration.
STATUS.RXNACK must be checked for each data packet transmitted before the next data packet transmission can
commence. The I2C master is not allowed to continue transmitting data packets if a NACK is given from the I2C slave.
Receiving Data Packets
When INTFLAG.SB is set, the I2C master will already have received one data packet. The I2C master must respond by
sending either an ACK or NACK. Sending a NACK might not be successfully executed as arbitration can be lost during
the transmission. In this case, a loss of arbitration will cause INTFLAG.SB to not be set on completion. Instead,
INTFLAG.MB will be used to indicate a change in arbitration. Handling of lost arbitration is the same as for data bit
transmission.
26.6.2.6 I2C Slave Operation
The I2C slave is byte-oriented and interrupt-based. The number of interrupts generated is kept at a minimum by
automatic handling of most events. Auto triggering of operations and a special smart mode, which can be enabled by
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writing a 1 to the Smart Mode Enable bit in the Control A register (CTRLA.SMEN), are included to reduce software’s
complexity and code size.
The I2C slave operates according to the behavior diagram shown in Figure 26-7. The circles with a capital S followed by
a number (S1, S2... etc.) indicate which node in the figure the bus logic can jump to based on software or hardware
interaction.
This diagram is used as reference for the description of the I2C slave operation throughout the document.
Figure 26-7. I2C Slave Behavioral Diagram
SLAVE ADDRESS INTERRUPT
S1
S3
S2
S
A
ADDRESS
R
S
W
SLAVE DATA INTERRUPT
S1
S2
Sr
S3
S
W
A
A
P
S1
P
S2
Sr
S3
DATA
A/A
SLAVE STOP INTERRUPT
W
Interrupt on STOP
Condition Enabled
S
W
S
W
A/A
DATA
S
W
A/A
S
W
Software interaction
The master provides data
on the bus
Addressed slave provides
data on the bus
Receiving Address Packets
When the I2C slave is properly configured, it will wait for a start condition to be detected. When a start condition is
detected, the successive address packet will be received and checked by the address match logic. If the received
address is not a match, the packet is rejected and the I2C slave waits for a new start condition. The I2C slave Address
Match bit in the Interrupt Flag register (INTFLAG.AMATCH) is set when a start condition followed by a valid address
packet is detected. SCL will be stretched until the I2C slave clears INTFLAG.AMATCH. Because the I2C slave holds the
clock by forcing SCL low, the software is given unlimited time to respond to the address.
The direction of a transaction is determined by reading the Read / Write Direction bit in the Status register
(STATUS.DIR), and the bit will be updated only when a valid address packet is received.
If the Transmit Collision bit in the Status register (STATUS.COLL) is set, this indicates that the last packet addressed to
the I2C slave had a packet collision. A collision causes the SDA and SCL lines to be released without any notification to
software. The next AMATCH interrupt is, therefore, the first indication of the previous packet’s collision. Collisions are
intended to follow the SMBus Address Resolution Protocol (ARP).
After the address packet has been received from the I2C master, one of two cases will arise based on transfer direction.
Case 1: Address packet accepted – Read flag set
The STATUS.DIR bit is one, indicating an I2C master read operation. The SCL line is forced low, stretching the bus clock.
If an ACK is sent, I2C slave hardware will set the Data Ready bit in the Interrupt Flag register (INTFLAG.DRDY),
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indicating data are needed for transmit. If not acknowledge is sent, the I2C slave will wait for a new start condition and
address match.
Typically, software will immediately acknowledge the address packet by sending an ACK/NACK bit. The I2C slave
command CTRLB.CMD = 3 can be used for both read and write operation as the command execution is dependent on
the STATUS.DIR bit.
Writing a one to INTFLAG.AMATCH will also cause an ACK/NACK to be sent corresponding to the CTRLB.ACKACT bit.
Case 2: Address packet accepted – Write flag set
The STATUS.DIR bit is cleared, indicating an I2C master write operation. The SCL line is forced low, stretching the bus
clock. If an ACK is sent, the I2C slave will wait for data to be received. Data, repeated start or stop can be received.
If not acknowledge is sent, the I2C slave will wait for a new start condition and address match.
Typically, software will immediately acknowledge the address packet by sending an ACK/NACK bit. The I2C slave
command CTRLB.CMD = 3 can be used for both read and write operation as the command execution is dependent on
STATUS.DIR.
Writing a one to INTFLAG.AMATCH will also cause an ACK/NACK to be sent corresponding to the CTRLB.ACKACT bit.
Receiving and Transmitting Data Packets
After the I2C slave has received an address packet, it will respond according to the direction either by waiting for the data
packet to be received or by starting to send a data packet by writing to DATA.DATA. When a data packet is received or
sent, INTFLAG.DRDY will be set. Then, if the I2C slave was receiving data, it will send an acknowledge according to
CTRLB.ACKACT.
Case 1: Data received
INTFLAG.DRDY is set, and SCL is held low pending SW interaction.
Case 2: Data sent
When a byte transmission is successfully completed, the INTFLAG.DRDY interrupt flag is set. If NACK is received, the
I2C slave must expect a stop or a repeated start to be received. The I2C slave must release the data line to allow the I2C
master to generate a stop or repeated start.
Upon stop detection, the Stop Received bit in the Interrupt Flag register (INTFLAG.PREC) will be set and the I2C slave
will return to the idle state.
26.6.3 Additional Features
26.6.3.1 SMBus
The I2C hardware incorporates hardware SCL low time-out, which allows a time-out to occur if the clock line is held low
too long. This time-out is driven by the GCLK_SERCOM_SLOW clock. The GCLK_SERCOM_SLOW clock is used to
accurately time the time-out and must be configured to used a 32kHz oscillator. The I2C interface also allows for a
SMBus compatible SDA hold time.
26.6.3.2 Smart Mode
The I2C interface incorporates a special smart mode that simplifies application code and minimizes the user interaction
needed to keep hold of the I2C protocol. The smart mode accomplishes this by letting the reading of DATA.DATA
automatically issue an ACK or NACK based on the state of CTRLB.ACKACT.
26.6.3.3 4-Wire Mode
Setting the Pin Usage bit in the Control A register (CTRLA.PINOUT) for master or slave to 4-wire mode enables
operation as shown in Figure 26-8. In this mode, the internal I2C tri-state drivers are bypassed, and an external, I2Ccompliant tri-state driver is needed when connecting to an I2C bus.
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Figure 26-8. I2C Pad Interface
SCL_OUT/
SDA_OUT
SCL_OUT/
SDA_OUT
pad
PINOUT
I2C
Driver
SCL/SDA
pad
SCL_IN/
SDA_IN
PINOUT
26.6.3.4 Quick Command
Setting the Quick Command Enable bit in the Control B register (CTRLB.QCEN) enables quick command. When quick
command is enabled, the corresponding interrupt flag is set immediately after the slave acknowledges the address. At
this point, the software can either issue a stop command or a repeated start by writing CTRLB.CMD or ADDR.ADDR.
26.6.4 Interrupts
The I2C slave has the following interrupt sources:
z
Data Ready (DRDY): this is an asynchronous interrupt and can be used to wake-up the device from any sleep
mode.
z
Address Match (AMATCH): this is an asynchronous interrupt and can be used to wake-up the device from any
sleep mode.
z
Stop Received (PREC): this is an asynchronous interrupt and can be used to wake-up the device from any sleep
mode.
The I2C master has the following interrupt sources:
z
Slave on Bus (SB): this is an asynchronous interrupt and can be used to wake-up the device from any sleep mode.
z
Master on Bus (MB): this is an asynchronous interrupt and can be used to wake-up the device from any sleep
mode.
Each interrupt source has an interrupt flag associated with it. The interrupt flag in the Interrupt Flag Status and Clear
register (INTFLAG) is set when the interrupt condition occurs. Each interrupt can be individually enabled by writing a one
to the corresponding bit in the Interrupt Enable Set register (INTENSET), and disabled by writing a one to the
corresponding bit in the Interrupt Enable Clear register (INTENCLR). An interrupt request is generated when the interrupt
flag is set and the corresponding interrupt is enabled. The interrupt request remains active until the interrupt flag is
cleared, the interrupt is disabled or the I2C is reset. See INTFLAG for details on how to clear interrupt flags.
The I2C has one common interrupt request line for all the interrupt sources. The user must read INTFLAG to determine
which interrupt condition is present.
Note that interrupts must be globally enabled for interrupt requests to be generated. Refer to “Nested Vector Interrupt
Controller” on page 30 for details.
26.6.5 Sleep Mode Operation
During I2C master operation, the generic clock (GCLK_SERCOMx_CORE) will continue to run in idle sleep mode. If the
Run In Standby bit in the Control A register (CTRLA.RUNSTDBY) is one, the GLK_SERCOMx_CORE will also run in
standby sleep mode. Any interrupt can wake up the device.
If CTRLA.RUNSTDBY is zero during I2C master operation, the GLK_SERCOMx_CORE will be disabled when an
ongoing transaction is finished. Any interrupt can wake up the device.
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During I2C slave operation, writing a one to CTRLA.RUNSTDBY will allow the Address Match interrupt to wake up the
device.
In I2C slave operation, all receptions will be dropped when CTRLA.RUNSTDBY is zero.
26.6.6 Synchronization
Due to the asynchronicity between CLK_SERCOMx_APB and GCLK_SERCOMx_CORE, some registers must be
synchronized when accessed. A register can require:
z
Synchronization when written
z
Synchronization when read
z
Synchronization when written and read
z
No synchronization
When executing an operation that requires synchronization, the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set immediately, and cleared when synchronization is complete.
If an operation that requires synchronization is executed while STATUS.SYNCBUSY is one, the bus will be stalled. All
operations will complete successfully, but the CPU will be stalled and interrupts will be pending as long as the bus is
stalled.
The following register needs synchronization when written:
z
Data (DATA) when in smart mode
The following bits need synchronization when written:
z
Software Reset bit in the Control A register (CTRLA.SWRST).
z
Enable bit in the Control A register (CTRLA.ENABLE).
z
Write to Bus State bits in the Status register (STATUS.BUSSTATE).
z
Address bits in the Address register (ADDR.ADDR) when in master operation.
Write-synchronization is denoted by the Write-Synchronized property in the register description.
The following register needs synchronization when read:
z
Data (DATA) when in master operation.
Read-synchronization is denoted by the Read-Synchronized property in the register description.
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26.7
Register Summary
Table 26-1. Register Summary – Slave Mode
Offset
Name
Bit
Pos.
0x00
7:0
0x01
15:8
RUNSTDBY
MODE[2:0]=100
ENABLE
SWRST
CTRLA
0x02
23:16
0x03
31:24
0x04
7:0
0x05
15:8
SDAHOLD[1:0]
PINOUT
LOWTOUT
AMODE[1:0]
SMEN
CTRLB
0x06
23:16
0x07
31:24
ACKACT
CMD[1:0]
0x08
Reserved
...
Reserved
0x0B
Reserved
0x0C
INTENCLR
7:0
DRDY
AMATCH
PREC
0x0D
INTENSET
7:0
DRDY
AMATCH
PREC
0x0E
INTFLAG
7:0
DRDY
AMATCH
PREC
0x0F
Reserved
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Table 26-1. Register Summary – Slave Mode (Continued)
Offset
Name
0x10
Bit
Pos.
7:0
CLKHOLD
15:8
SYNCBUSY
LOWTOUT
SR
DIR
RXNACK
COLL
BUSERR
STATUS
0x11
0x12
Reserved
0x13
Reserved
0x14
7:0
0x15
ADDR[6:0]
GENCEN
15:8
ADDR
0x16
23:16
0x17
31:24
0x18
7:0
ADDRMASK[6:0]
DATA[7:0]
DATA
0x19
15:8
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Table 26-2. Register Summary – Master Mode
Offset
Name
Bit
Pos
0x00
7:0
0x01
15:8
RUNSTDBY
MODE[2:0]=101
ENABLE
SWRST
CTRLA
0x02
23:16
0x03
31:24
0x04
7:0
0x05
SDAHOLD[1:0]
LOWTOUT
PINOUT
INACTOUT[1:0]
15:8
QCEN
SMEN
CTRLB
0x06
23:16
0x07
31:24
0x08
DBGCTRL
0x09
Reserved
0x0A
ACKACT
CMD[1:0]
7:0
DBGSTOP
7:0
BAUD[7:0]
15:8
BAUDLOW[7:0]
BAUD
0x0B
0x0C
INTENCLR
7:0
SB
MB
0x0D
INTENSET
7:0
SB
MB
0x0E
INTFLAG
7:0
SB
MB
0x0F
Reserved
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Table 26-2. Register Summary – Master Mode (Continued)
Offset
Name
0x10
Bit
Pos
7:0
CLKHOLD
15:8
SYNCBUSY
LOWTOUT
BUSSTATE[1:0]
RXNACK
ARBLOST
BUSERR
STATUS
0x11
0x12
Reserved
0x13
Reserved
0x14
7:0
ADDR[7:0]
ADDR
0x15
15:8
0x16
Reserved
0x17
Reserved
0x18
7:0
DATA[7:0]
DATA
0x19
15:8
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26.8
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-Protected property in each individual register description. Refer to“Register Access Protection” on page 396 for
details.
Some registers require synchronization when read and/or written. Synchronization is denoted by the Write-Synchronized
or the Read-Synchronized property in each individual register description. Refer to “Synchronization” on page 407 for
details.
Some registers are enable-protected, meaning they can only be written when the I2C is disabled. Enable-protection is
denoted by the Enable-Protected property in each individual register description.
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26.8.1 I2C Slave Register Description
26.8.1.1 Control A
Name:
CTRLA
Offset:
0x00
Reset:
0x00000000
Property:
Write-Protected, Enable-Protected, Write-Synchronized
Bit
31
30
29
28
27
26
25
24
LOWTOUT
Access
R
R/W
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
SDAHOLD[1:0]
PINOUT
Access
R
R
R/W
R/W
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ENABLE
SWRST
RUNSTDBY
Access
Reset
MODE[2:0]=100
R/W
R
R
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bit 31 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 30 – LOWTOUT: SCL Low Time-Out
This bit enables the SCL low time-out. If SCL is held low for 25ms-35ms, the slave will release its clock hold, if
enabled, and reset the internal state machine. Any interrupts set at the time of time-out will remain set.
0: Time-out disabled.
1: Time-out enabled.
This bit is not synchronized.
z
Bits 29:22 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 21:20 – SDAHOLD[1:0]: SDA Hold Time
These bits define the SDA hold time with respect to the negative edge of SCL.
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Table 26-3. SDA Hold Time
Value
Name
Description
0x0
DIS
Disabled
0x1
75
50-100ns hold time
0x2
450
300-600ns hold time
0x3
600
400-800ns hold time
These bits are not synchronized.
z
Bits 19:17 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 16 – PINOUT: Pin Usage
This bit sets the pin usage to either two- or four-wire operation:
0: 4-wire operation disabled
1: 4-wire operation enabled
This bit is not synchronized.
z
Bits 15:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 7 – RUNSTDBY: Run in Standby
This bit defines the functionality in standby sleep mode.
0: Disabled – All reception is dropped.
1: Wake on address match, if enabled.
This bit is not synchronized.
z
Bits 6:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 4:2 – MODE[2:0]: Operating Mode
These bits must be written to 0x04 to select the I2C slave serial communication interface of the SERCOM.
These bits are not synchronized.
z
Bit 1 – ENABLE: Enable
0: The peripheral is disabled.
1: The peripheral is enabled.
Due to synchronization, there is delay from writing CTRLA.ENABLE until the peripheral is enabled/disabled. The
value written to CTRL.ENABLE will read back immediately and the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set. STATUS.SYNCBUSY will be cleared when the operation is complete.
This bit is not enable-protected.
z
Bit 0 – SWRST: Software Reset
0: There is no reset operation ongoing.
1: The reset operation is ongoing.
Writing a zero to this bit has no effect.
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Writing a one to this bit resets all registers in the SERCOM, except DBGCTRL, to their initial state, and the SERCOM will be disabled.
Writing a one to CTRLA.SWRST will always take precedence, meaning that all other writes in the same write-operation will be discarded.
Due to synchronization, there is a delay from writing CTRLA.SWRST until the reset is complete. CTRLA.SWRST
and STATUS.SYNCBUSY will both be cleared when the reset is complete.
This bit is not enable-protected.
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26.8.1.2 Control B
Name:
CTRLB
Offset:
0x04
Reset:
0x00000000
Property:
Write-Protected, Enable-Protected, Write-Synchronized
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
ACKACT
CMD[1:0]
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
AMODE[1:0]
Access
SMEN
R/W
R/W
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bits 31:19 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 18 – ACKACT: Acknowledge Action
0: Send ACK
1: Send NACK
The Acknowledge Action (ACKACT) bit defines the slave's acknowledge behavior after an address or data byte is
received from the master. The acknowledge action is executed when a command is written to the CMD bits. If
smart mode is enabled (CTRLB.SMEN is one), the acknowledge action is performed when the DATA register is
read.
This bit is not enable-protected.
z
Bits 17:16 – CMD[1:0]: Command
Writing the Command bits (CMD) triggers the slave operation as defined in Table 26-4. The CMD bits are strobe
bits, and always read as zero. The operation is dependent on the slave interrupt flags, INTFLAG.DRDY and INTFLAG.AMATCH, in addition to STATUS.DIR (See Table 26-4).
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All interrupt flags (INTFLAG.DRDY, INTFLAG.AMATCH and INTFLAG.PREC) are automatically cleared when a
command is given.
This bit is not enable-protected.
Table 26-4. Command Description
CMD[1:0]
DIR
Action
0x0
X
(No action)
0x1
X
(Reserved)
Used to complete a transaction in response to a data interrupt (DRDY)
0x2
0 (Master write)
Execute acknowledge action succeeded by waiting for any start (S/Sr) condition
1 (Master read)
Wait for any start (S/Sr) condition
Used in response to an address interrupt (AMATCH)
0 (Master write)
Execute acknowledge action succeeded by reception of next byte
1 (Master read)
Execute acknowledge action succeeded by slave data interrupt
0x3
Used in response to a data interrupt (DRDY)
z
0 (Master write)
Execute acknowledge action succeeded by reception of next byte
1 (Master read)
Execute a byte read operation followed by ACK/NACK reception
Bits 15:14 – AMODE[1:0]: Address Mode
These bits set the addressing mode according to Table 26-5.
Table 26-5. Address Mode Description
Value
Name
Description
0x0
MASK
The slave responds to the address written in ADDR.ADDR masked by the value in
ADDR.ADDRMASK(1).
0x1
2_ADDRS
The slave responds to the two unique addresses in ADDR.ADDR and ADDR.ADDRMASK.
0x2
RANGE
The slave responds to the range of addresses between and including ADDR.ADDR and
ADDR.ADDRMASK. ADDR.ADDR is the upper limit.
0x3
-
Reserved.
Note:
1.
See “SERCOM – Serial Communication Interface” on page 336 for additional information.
These bits are not write-synchronized.
z
Bits 13:9 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 8 – SMEN: Smart Mode Enable
This bit enables smart mode. When smart mode is enabled, acknowledge action is sent when DATA.DATA is
read.
0: Smart mode is disabled.
1: Smart mode is enabled.
This bit is not write-synchronized.
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z
Bits 7:0 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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26.8.1.3 Interrupt Enable Clear
This register allows the user to disable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Set register (INTENSET).
Name:
INTENCLR
Offset:
0x0C
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
DRDY
AMATCH
PREC
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – DRDY: Data Ready Interrupt Enable
0: The Data Ready interrupt is disabled.
1: The Data Ready interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Data Ready bit, which disables the Data Ready interrupt.
z
Bit 1 – AMATCH: Address Match Interrupt Enable
0: The Address Match interrupt is disabled.
1: The Address Match interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Address Match Interrupt Enable bit, which disables the Address Match
interrupt.
z
Bit 0 – PREC: Stop Received Interrupt Enable
0: The Stop Received interrupt is disabled.
1: The Stop Received interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Stop Received bit, which disables the Stop Received interrupt.
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26.8.1.4 Interrupt Enable Set
This register allows the user to enable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Clear register (INTENCLR).
Name:
INTENSET
Offset:
0x0D
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
DRDY
AMATCH
PREC
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – DRDY: Data Ready Interrupt Enable
0: The Data Ready interrupt is disabled.
1: The Data Ready interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Data Ready bit, which enables the Data Ready interrupt.
z
Bit 1 – AMATCH: Address Match Interrupt Enable
0: The Address Match interrupt is disabled.
1: The Address Match interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Address Match Interrupt Enable bit, which enables the Address Match interrupt.
z
Bit 0 – PREC: Stop Received Interrupt Enable
0: The Stop Received interrupt is disabled.
1: The Stop Received interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Stop Received bit, which enables the Stop Received interrupt.
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26.8.1.5 Interrupt Flag Status and Clear
Name:
INTFLAG
Offset:
0x0E
Reset:
0x00
Property:
-
Bit
7
6
5
4
3
2
1
0
DRDY
AMATCH
PREC
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – DRDY: Data Ready
This flag is set when a I2C slave byte transmission is successfully completed.
The flag is cleared by hardware when either:
z
Writing to the DATA register.
z
Reading the DATA register with smart mode enabled.
z
Writing a valid command to the CMD register.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Data Ready interrupt flag. Optionally, the flag can be cleared manually by writing a one to INTFLAG.DRDY.
z
Bit 1 – AMATCH: Address Match
This flag is set when the I2C slave address match logic detects that a valid address has been received.
The flag is cleared by hardware when CTRL.CMD is written.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Address Match interrupt flag. Optionally the flag can be cleared manually by
writing a one to INTFLAG.AMATCH. When cleared, an ACK/NACK will be sent according to CTRLB.ACKACT.
z
Bit 0 – PREC: Stop Received
This flag is set when a stop condition is detected for a transaction being processed. A stop condition detected
between a bus master and another slave will not set this flag.
This flag is cleared by hardware after a command is issued on the next address match.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Stop Received interrupt flag. Optionally, the flag can be cleared manually by
writing a one to INTFLAG.PREC.
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26.8.1.6 Status
Name:
STATUS
Offset:
0x10
Reset:
0x0000
Property:
-
Bit
15
14
13
12
11
10
9
8
SYNCBUSY
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
CLKHOLD
LOWTOUT
SR
DIR
RXNACK
COLL
BUSERR
Access
R
R/W
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bit 15 – SYNCBUSY: Synchronization Busy
This bit is set when the synchronization of registers between clock domains is started.
This bit is cleared when the synchronization of registers between the clock domains is complete.
z
Bits 14:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 7 – CLKHOLD: Clock Hold
The slave Clock Hold bit (STATUS.CLKHOLD) is set when the slave is holding the SCL line low, stretching the I2C
clock. Software should consider this bit a read-only status flag that is set when INTFLAG.DRDY or INTFLAG.AMATCH is set.
This bit is automatically cleared when the corresponding interrupt is also cleared.
z
Bit 6 – LOWTOUT: SCL Low Time-out
This bit is set if an SCL low time-out occurs.
This bit is cleared automatically if responding to a new start condition with ACK or NACK (write 3 to CTRLB.CMD)
or when INTFLAG.AMATCH is cleared.
0: No SCL low time-out has occurred.
1: SCL low time-out has occurred.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the status.
z
Bit 5 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 4 – SR: Repeated Start
When INTFLAG.AMATCH is raised due to an address match, SR indicates a repeated start or start condition.
0: Start condition on last address match
1: Repeated start condition on last address match
This flag is only valid while the INTFLAG.AMATCH flag is one.
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z
Bit 3 – DIR: Read / Write Direction
The Read/Write Direction (STATUS.DIR) bit stores the direction of the last address packet received from a master.
0: Master write operation is in progress.
1: Master read operation is in progress.
z
Bit 2 – RXNACK: Received Not Acknowledge
This bit indicates whether the last data packet sent was acknowledged or not.
0: Master responded with ACK.
1: Master responded with NACK.
z
Bit 1 – COLL: Transmit Collision
If set, the I2C slave was not able to transmit a high data or NACK bit, the I2C slave will immediately release the
SDA and SCL lines and wait for the next packet addressed to it.
This flag is intended for the SMBus address resolution protocol (ARP). A detected collision in non-ARP situations
indicates that there has been a protocol violation, and should be treated as a bus error.
Note that this status will not trigger any interrupt, and should be checked by software to verify that the data were
sent correctly. This bit is cleared automatically if responding to an address match with an ACK or a NACK (writing
0x3 to CTRLB.CMD), or INTFLAG.AMATCH is cleared.
0: No collision detected on last data byte sent.
1: Collision detected on last data byte sent.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the status.
z
Bit 0 – BUSERR: Bus Error
The Bus Error bit (STATUS.BUSERR) indicates that an illegal bus condition has occurred on the bus, regardless
of bus ownership. An illegal bus condition is detected if a protocol violating start, repeated start or stop is detected
on the I2C bus lines. A start condition directly followed by a stop condition is one example of a protocol violation. If
a time-out occurs during a frame, this is also considered a protocol violation, and will set STATUS.BUSERR.
This bit is cleared automatically if responding to an address match with an ACK or a NACK (writing 0x3 to
CTRLB.CMD) or INTFLAG.AMATCH is cleared.
0: No bus error detected.
1: Bus error detected.
Writing a one to this bit will clear the status.
Writing a zero to this bit has no effect.
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26.8.1.7 Address
Name:
ADDR
Offset:
0x14
Reset:
0x00000000
Property:
Write-Protected, Enable-Protected
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
ADDRMASK[6:0]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ADDR[6:0]
Access
Reset
GENCEN
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 31:24 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 23:17 – ADDRMASK[6:0]: Address Mask
The ADDRMASK bits acts as a second address match register, an address mask register or the lower limit of an
address range, depending on the CTRLB.AMODE setting.
z
Bits 16:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 7:1 – ADDR[6:0]: Address
The slave address (ADDR) bits contain the I2C slave address used by the slave address match logic to determine
if a master has addressed the slave. When using 7-bit addressing, the address register (ADDR.ADDR) represents
the slave address.
If using 10-bit addressing, the address match logic only supports hardware address recognition of the first 2 bits of
a 10-bit address. If writing ADDR.ADDR = "0b1111 0xx," 'xx' represents bits 9 and 8 or the slave address. The next
byte received is bits 7 to 0 in the 10-bit address, and this must be handled by software.
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When the address match logic detects a match, INTFLAG.AMATCH is set and STATUS.DIR is updated to indicate
whether it is a read or a write transaction.
z
Bit 0 – GENCEN: General Call Address Enable
Writing a one to GENCEN enables general call address recognition. A general call address is an address of all
zeroes with the direction bit written to zero (master write).
0: General call address recognition disabled.
1: General call address recognition enabled.
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26.8.1.8 Data
Name:
DATA
Offset:
0x18
Reset:
0x0000
Property:
Write-Synchronized, Read-Synchronized
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DATA[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 15:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 7:0 – DATA[7:0]: Data
The slave data register I/O location (DATA.DATA) provides access to the master transmit and receive data buffers. Reading valid data or writing data to be transmitted can be successfully done only when SCL is held low by
the slave (STATUS.CLKHOLD is set). An exception occurs when reading the last data byte after the stop condition
has been received.
Accessing DATA.DATA auto-triggers I2C bus operations. The operation performed depends on the state of
CTRLB.ACKACT, CTRLB.SMEN and the type of access (read/write).
Writing or reading DATA.DATA when not in smart mode does not require synchronization.
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26.8.2 I2C Master Register Description
26.8.2.1 Control A
Name:
CTRLA
Offset:
0x00
Reset:
0x00000000
Property:
Write-Protected, Enable-Protected, Write-Synchronized
Bit
31
30
LOWTOUT
29
28
27
26
25
24
INACTOUT[1:0]
Access
R
R/W
R/W
R/W
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
SDAHOLD[1:0]
PINOUT
Access
R
R
R/W
R/W
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ENABLE
SWRST
RUNSTDBY
Access
Reset
MODE[2:0]=101
R/W
R
R
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bit 31 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 30 – LOWTOUT: SCL Low Time-Out
This bit enables the SCL low time-out. If SCL is held low for 25ms-35ms, the master will release its clock hold, if
enabled, and complete the current transaction. A stop condition will automatically be transmitted.
INTFLAG.SB or INTFLAG.MB will be set as normal, but the clock hold will be released. The STATUS.LOWTOUT
and STATUS.BUSERR status bits will be set.
0: Time-out disabled.
1: Time-out enabled.
This bit is not synchronized.
z
Bits 29:28 – INACTOUT[1:0]: Inactive Time-Out
If the inactive bus time-out is enabled and the bus is inactive for longer than the time-out setting, the bus state logic
will be set to idle. An inactive bus arise when either an I2C master or slave is holding the SCL low. The available
time-outs are given in Table 26-6.
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Enabling this option is necessary for SMBus compatibility, but can also be used in a non-SMBus set-up.
Table 26-6. Inactive Timout
Value
Name
Description
0x0
DIS
Disabled
0x1
55US
5-6 SCL cycle time-out (50-60µs)
0x2
105US
10-11 SCL cycle time-out (100-110µs)
0x3
205US
20-21 SCL cycle time-out (200-210µs)
Calculated time-out periods are based on a 100kHz baud rate.
These bits are not synchronized.
z
Bits 27:22 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 21:20 – SDAHOLD[1:0]: SDA Hold Time
These bits define the SDA hold time with respect to the negative edge of SCL.
Table 26-7. SDA Hold Time
Value
Name
Description
0x0
DIS
Disabled
0x1
75NS
50-100ns hold time
0x2
450NS
300-600ns hold time
0x3
600NS
400-800ns hold time
These bits are not synchronized.
z
Bits 19:17 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 16 – PINOUT: Pin Usage
This bit set the pin usage to either two- or four-wire operation:
0: 4-wire operation disabled.
1: 4-wire operation enabled.
This bit is not synchronized.
z
Bits 15:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 7 – RUNSTDBY: Run in Standby
This bit defines the functionality in standby sleep mode.
0: GCLK_SERCOMx_CORE is disabled and the I2C master will not operate in standby sleep mode.
1: GCLK_SERCOMx_CORE is enabled in all sleep modes allowing the master to operate in standby sleep mode.
This bit is not synchronized.
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z
Bits 6:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 4:2 – MODE[2:0]: Operating Mode
These bits must be written to 0x5 to select the I2C master serial communication interface of the SERCOM.
These bits are not synchronized.
z
Bit 1 – ENABLE: Enable
0: The peripheral is disabled.
1: The peripheral is enabled.
Due to synchronization, there is delay from writing CTRLA.ENABLE until the peripheral is enabled/disabled. The
value written to CTRL.ENABLE will read back immediately and the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set. STATUS.SYNCBUSY will be cleared when the operation is complete.
This bit is not enable-protected.
z
Bit 0 – SWRST: Software Reset
0: There is no reset operation ongoing.
1: The reset operation is ongoing.
Writing a zero to this bit has no effect.
Writing a one to this bit resets all registers in the SERCOM, except DBGCTRL, to their initial state, and the SERCOM will be disabled.
Writing a one to CTRLA.SWRST will always take precedence, meaning that all other writes in the same write-operation will be discarded.
Due to synchronization there is a delay from writing CTRLA.SWRST until the reset is complete. CTRLA.SWRST
and STATUS.SYNCBUSY will both be cleared when the reset is complete.
This bit is not enable-protected.
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26.8.2.2 Control B
Name:
CTRLB
Offset:
0x04
Reset:
0x00000000
Property:
Write-Protected, Enable-Protected, Write-Synchronized
Bit
31
30
29
28
27
26
25
24
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
23
22
21
20
19
18
17
16
ACKACT
CMD[1:0]
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
QCEN
SMEN
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bits 31:19 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 18 – ACKACT: Acknowledge Action
The Acknowledge Action (ACKACT) bit defines the I2C master's acknowledge behavior after a data byte is
received from the I2C slave. The acknowledge action is executed when a command is written to CTRLB.CMD, or if
smart mode is enabled (CTRLB.SMEN is written to one), when DATA.DATA is read.
0: Send ACK.
1: Send NACK.
This bit is not enable-protected.
This bit is not write-synchronized.
z
Bits 17:16 – CMD[1:0]: Command
Writing the Command bits (CMD) triggers the master operation as defined in Table 26-8. The CMD bits are strobe
bits, and always read as zero. The acknowledge action is only valid in master read mode. In master write mode, a
command will only result in a repeated start or stop condition. The CTRLB.ACKACT bit and the CMD bits can be
written at the same time, and then the acknowledge action will be updated before the command is triggered.
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Commands can only be issued when the Slave on Bus interrupt flag (INTFLAG.SB) or Master on Bus interrupt flag
(INTFLAG.MB) is one.
If CMD 0x1 is issued, a repeated start will be issued followed by the transmission of the current address in
ADDR.ADDR. If another address is desired, ADDR.ADDR must be written instead of the CMD bits. This will trigger
a repeated start followed by transmission of the new address.
Issuing a command will set STATUS.SYNCBUSY.
Table 26-8. Command Description
CMD[1:0]
DIR
Action
0x0
X
(No action)
0x1
X
Execute acknowledge action succeeded by repeated Start
0 (Write)
No operation
1 (Read)
Execute acknowledge action succeeded by a byte read operation
X
Execute acknowledge action succeeded by issuing a stop condition
0x2
0x3
These bits are not enable-protected.
z
Bits 15:10 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 9 – QCEN: Quick Command Enable
Setting the Quick Command Enable bit (QCEN) enables quick command.
0: Quick Command is disabled.
1: Quick Command is enabled.
This bit is not write-synchronized.
z
Bit 8 – SMEN: Smart Mode Enable
This bit enables smart mode. When smart mode is enabled, acknowledge action is sent when DATA.DATA is
read.
0: Smart mode is disabled.
1: Smart mode is enabled.
This bit is not write-synchronized.
z
Bits 7:0 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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26.8.2.3 Debug Control
Name:
DBGCTRL
Offset:
0x08
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
DBGSTOP
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – DBGSTOP: Debug Stop Mode
This bit controls functionality when the CPU is halted by an external debugger.
0: The baud-rate generator continues normal operation when the CPU is halted by an external debugger.
1: The baud-rate generator is halted when the CPU is halted by an external debugger.
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26.8.2.4 Baud Rate
Name:
BAUD
Offset:
0x0A
Reset:
0x0000
Property:
Write-Protected, Enable-Protected
Bit
15
14
13
12
11
10
9
8
BAUDLOW[7:0]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
BAUD[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 15:8 – BAUDLOW[7:0]: Master Baud Rate Low
If the Master Baud Rate Low bit group (BAUDLOW) has a non-zero value, the SCL low time will be described by
the value written.
For more information on how to calculate the frequency, see “SERCOM I2C – SERCOM Inter-Integrated Circuit”
on page 394.
z
Bits 7:0 – BAUD[7:0]: Master Baud Rate
The Master Baud Rate bit group (BAUD) is used to derive the SCL high time if BAUD.BAUDLOW is non-zero. If
BAUD.BAUDLOW is zero, BAUD will be used to generate both high and low periods of the SCL.
For more information on how to calculate the frequency, see “SERCOM I2C – SERCOM Inter-Integrated Circuit”
on page 394.
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26.8.2.5 Interrupt Enable Clear
This register allows the user to disable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Set register (INTENSET).
Name:
INTENCLR
Offset:
0x0C
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
SB
MB
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – SB: Slave on Bus Interrupt Enable
0: The Slave on Bus interrupt is disabled.
1: The Slave on Bus interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Slave on Bus Interrupt Enable bit, which disables the Slave on Bus interrupt.
z
Bit 0 – MB: Master on Bus Interrupt Enable
0: The Master on Bus interrupt is disabled.
1: The Master on Bus interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Master on Bus Interrupt Enable bit, which disables the Master on Bus
interrupt.
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26.8.2.6 Interrupt Enable Set
This register allows the user to enable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Clear register (INTENCLR).
Name:
INTENSET
Offset:
0x0D
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
SB
MB
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – SB: Slave on Bus Interrupt Enable
0: The Slave on Bus interrupt is disabled.
1: The Slave on Bus interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Slave on Bus Interrupt Enable bit, which enables the Slave on Bus interrupt.
z
Bit 0 – MB: Master on Bus Interrupt Enable
0: The Master on Bus interrupt is disabled.
1: The Master on Bus interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Master on Bus Interrupt Enable bit, which enables the Master on Bus interrupt.
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26.8.2.7 Interrupt Flag Status and Clear
Name:
INTFLAG
Offset:
0x0E
Reset:
0x00
Property:
-
Bit
7
6
5
4
3
2
1
0
SB
MB
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – SB: Slave on Bus
The Slave on Bus flag (SB) is set when a byte is successfully received in master read mode, i.e., no arbitration lost
or bus error occurred during the operation. When this flag is set, the master forces the SCL line low, stretching the
I2C clock period. The SCL line will be released and SB will be cleared on one of the following actions:
z
Writing to ADDR.ADDR
z
Writing to DATA.DATA
z
Reading DATA.DATA when smart mode is enabled (CTRLB.SMEN)
z
Writing a valid command to CTRLB.CMD
Writing a one to this bit location will clear the SB flag. The transaction will not continue or be terminated until one of
the above actions is performed.
Writing a zero to this bit has no effect.
z
Bit 0 – MB: Master on Bus
The Master on Bus flag (MB) is set when a byte is transmitted in master write mode. The flag is set regardless of
the occurrence of a bus error or an arbitration lost condition. MB is also set when arbitration is lost during sending
of NACK in master read mode, and when issuing a start condition if the bus state is unknown. When this flag is set
and arbitration is not lost, the master forces the SCL line low, stretching the I2C clock period. The SCL line will be
released and MB will be cleared on one of the following actions:
z
Writing to ADDR.ADDR
z
Writing to DATA.DATA
z
Reading DATA.DATA when smart mode is enabled (CTRLB.SMEN)
z
Writing a valid command to CTRLB.CMD
If arbitration is lost, writing a one to this bit location will clear the MB flag.
If arbitration is not lost, writing a one to this bit location will clear the MB flag. The transaction will not continue or be
terminated until one of the above actions is performed.
Writing a zero to this bit has no effect.
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26.8.2.8 Status
Name:
STATUS
Offset:
0x10
Reset:
0x0000
Property:
Write-Synchronized
Bit
15
14
13
12
11
10
9
8
SYNCBUSY
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
CLKHOLD
LOWTOUT
RXNACK
ARBLOST
BUSERR
Access
R
R/W
R
R/W
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
BUSSTATE[1:0]
Bit 15 – SYNCBUSY: Synchronization Busy
This bit is cleared when the synchronization of registers between the clock domains is complete.
This bit is set when the synchronization of registers between clock domains is started.
z
Bits 14:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 7 – CLKHOLD: Clock Hold
The Master Clock Hold flag (STATUS.CLKHOLD) is set when the master is holding the SCL line low, stretching
the I2C clock. Software should consider this bit a read-only status flag that is set when INTFLAG.SB or INTFLAG.MB is set. When the corresponding interrupt flag is cleared and the next operation is given, this bit is
automatically cleared.
Writing a zero to this bit has no effect.
Writing a one to this bit has no effect.
This bit is not write-synchronized.
z
Bit 6 – LOWTOUT: SCL Low Time-Out
This bit is set if an SCL low time-out occurs.
Writing a one to this bit location will clear STATUS.LOWTOUT. Normal use of the I2C interface does not require
the LOWTOUT flag to be cleared by this method. This flag is automatically cleared when writing to the ADDR
register.
Writing a zero to this bit has no effect.
This bit is not write-synchronized.
z
Bits 5:4 – BUSSTATE[1:0]: Bus State
These bits indicate the current I2C bus state as defined in Table 26-9. After enabling the SERCOM as an I2C master, the bus state will be unknown.
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Table 26-9. Bus State
Value
Name
0x0
Unknown
0x1
Idle
0x2
Owner
0x3
Busy
Description
The bus state is unknown to the I2C master and will wait for a stop condition to be
detected or wait to be forced into an idle state by software
The bus state is waiting for a transaction to be initialized
The I2C master is the current owner of the bus
Some other I2C master owns the bus
When the master is disabled, the bus-state is unknown. When in the unknown state, writing 0x1 to BUSSTATE forces the
bus state into the idle state. The bus state cannot be forced into any other state.
Writing STATUS.BUSSTATE to idle will set STATUS.SYNCBUSY.
z
Bit 3 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 2 – RXNACK: Received Not Acknowledge
This bit indicates whether the last address or data packet sent was acknowledged or not.
0: Slave responded with ACK.
1: Slave responded with NACK.
Writing a zero to this bit has no effect.
Writing a one to this bit has no effect.
This bit is not write-synchronized.
z
Bit 1 – ARBLOST: Arbitration Lost
The Arbitration Lost flag (STATUS.ARBLOST) is set if arbitration is lost while transmitting a high data bit or a
NACK bit, or while issuing a start or repeated start condition on the bus. The Master on Bus interrupt flag (INTFLAG.MB) will be set when STATUS.ARBLOST is set.
Writing the ADDR.ADDR register will automatically clear STATUS.ARBLOST.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear it.
This bit is not write-synchronized.
z
Bit 0 – BUSERR: Bus Error
The Bus Error bit (STATUS.BUSERR) indicates that an illegal bus condition has occurred on the bus, regardless
of bus ownership. An illegal bus condition is detected if a protocol violating start, repeated start or stop is detected
on the I2C bus lines. A start condition directly followed by a stop condition is one example of a protocol violation. If
a time-out occurs during a frame, this is also considered a protocol violation, and will set BUSERR.
If the I2C master is the bus owner at the time a bus error occurs, STATUS.ARBLOST and INTFLAG.MB will be set
in addition to BUSERR.
Writing the ADDR.ADDR register will automatically clear the BUSERR flag.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear it.
This bit is not write-synchronized.
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26.8.2.9 Address
Name:
ADDR
Offset:
0x14
Reset:
0x0000
Property:
Write-Synchronized
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ADDR[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 15:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 7:0 – ADDR[7:0]: Address
When ADDR is written, the consecutive operation will depend on the bus state:
Unknown: INTFLAG.MB and STATUS.BUSERR are set, and the operation is terminated.
Busy: The I2C master will await further operation until the bus becomes idle.
Idle: The I2C master will issue a start condition followed by the address written in ADDR. If the address is acknowledged, SCL is forced and held low, and STATUS.CLKHOLD and INTFLAG.MB are set.
Owner: A repeated start sequence will be performed. If the previous transaction was a read, the acknowledge
action is sent before the repeated start bus condition is issued on the bus. Writing ADDR to issue a repeated start
is performed while INTFLAG.MB or INTFLAG.SB is set.
Regardless of winning or losing arbitration, the entire address will be sent. If arbitration is lost, only ones are transmitted from the point of losing arbitration and the rest of the address length.
STATUS.BUSERR, STATUS.ARBLOST, INTFLAG.MB and INTFLAG.SB will be cleared when ADDR is written.
The ADDR register can be read at any time without interfering with ongoing bus activity, as a read access does not
trigger the master logic to perform any bus protocol related operations.
The I2C master control logic uses bit 0 of ADDR as the bus protocol’s read/write flag (R/W); 0 for write and 1 for
read.
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26.8.2.10 Data
Name:
DATA
Offset:
0x18
Reset:
0x0000
Property:
Write-Synchronized, Read-Synchronized
Bit
15
14
13
12
11
10
9
8
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DATA[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 15:8 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 7:0 – DATA[7:0]: Data
The master data register I/O location (DATA) provides access to the master transmit and receive data buffers.
Reading valid data or writing data to be transmitted can be successfully done only when SCL is held low by the
master (STATUS.CLKHOLD is set). An exception occurs when reading the last data byte after the stop condition
has been sent.
Accessing DATA.DATA auto-triggers I2C bus operations. The operation performed depends on the state of
CTRLB.ACKACT, CTRLB.SMEN and the type of access (read/write).
Writing or reading DATA.DATA when not in smart mode does not require synchronization.
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27.
TC – Timer/Counter
27.1
Overview
The TC consists of a counter, a prescaler, compare/capture channels and control logic. The counter can be set to count
events, or it can be configured to count clock pulses. The counter, together with the compare/capture channels, can be
configured to timestamp input events, allowing capture of frequency and pulse width. It can also perform waveform
generation, such as frequency generation and pulse-width modulation (PWM).
27.2
Features
z Selectable configuration
z
8-, 16- or 32-bit TC, with compare/capture channels
z Waveform generation
z
z
Frequency generation
Single-slope pulse-width modulation
z Input capture
z
Event capture
Frequency capture
z Pulse-width capture
z
z One input event
z Interrupts/output events on:
z
z
Counter overflow/underflow
Compare match or capture
z Internal prescaler
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Block Diagram
Figure 27-1. Timer/Counter Block Diagram
BASE COUNTER
PER
PRESCALER
count
COUNTER
OVF/UNF
(INT Req.)
clear
load
COUNT
CONTROL
LOGIC
direction
ERR
(INT Req.)
=0
Zero
Update
Top
=
event
27.3
Compare / Capture
CONTROL
LOGIC
WOx Out
WAVEFORM
GENERATION
CC0
match
=
MCx
(INT Req.)
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27.4
Signal Description
Signal Name
Type
Description
WO[1:0]
Digital output
Waveform output
Refer to “I/O Multiplexing and Considerations” on page 16 for details on the pin mapping for this peripheral. One signal
can be mapped on several pins.
27.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
27.5.1 I/O Lines
Using the TC’s I/O lines requires the I/O pins to be configured. Refer to “PORT” on page 287 for details.
27.5.2 Power Management
The TC can continue to operate in any sleep mode where the selected source clock is running. The TC interrupts can be
used to wake up the device from sleep modes. The events can trigger other operations in the system without exiting
sleep modes. Refer to “PM – Power Manager” on page 107 for details on the different sleep modes.
27.5.3 Clocks
The TC bus clock (CLK_TCx_APB, where x represents the specific TC instance number) can be enabled and disabled in
the Power Manager, and the default state of CLK_TCx_APB can be found in the Peripheral Clock Masking section in
“PM – Power Manager” on page 107.
The different TC instances are paired, even and odd, starting from TC0, and use the same generic clock, GCLK_TCx.
This means that the TC instances in a TC pair cannot be set up to use different GCLK_TCx clocks.
This generic clock is asynchronous to the user interface clock (CLK_TCx_APB). Due to this asynchronicity, accessing
certain registers will require synchronization between the clock domains. Refer to “Synchronization” on page 452 for
further details.
27.5.4 Interrupts
The interrupt request line is connected to the Interrupt Controller. Using the TC interrupts requires the interrupt controller
to be configured first. Refer to “Nested Vector Interrupt Controller” on page 30 for details.
27.5.5 Events
To use the TC event functionality, the corresponding events need to be configured in the event system. Refer to “EVSYS
– Event System” on page 313 for details.
27.5.6 Debug Operation
When the CPU is halted in debug mode the TC will halt normal operation. The TC can be forced to continue operation
during debugging. Refer to the DBGCTRL register for details.
27.5.7 Register Access Protection
All registers with write-access are optionally write-protected by the peripheral access controller (PAC), except the
following registers:
z
Interrupt Flag register (INTFLAG)
z
Status register (STATUS)
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z
Read Request register (READREQ)
z
Count register (COUNT), “Counter Value” on page 474
z
Period register (PER), “ Period Value” on page 477
z
Compare/Capture Value registers (CCx), “ Compare/Capture” on page 478
Write-protection is denoted by the Write-Protection property in the register description.
When the CPU is halted in debug mode, all write-protection is automatically disabled.
Write-protection does not apply for accesses through an external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
27.5.8 Analog Connections
Not applicable.
27.6
Functional Description
27.6.1 Principle of Operation
The counter in the TC can be set to count on events from the Event System, or on the GCLK_TCx frequency. The pulses
from GCLK_TCx will go through the prescaler, where it is possible to divide the frequency down.
The value in the counter is passed to the compare/capture channels, where it can either be compared with user defined
values or captured on a predefined event.
The TC can be configured as an 8-, 16- or 32-bit counter. Which mode is chosen will determine the maximum range of
the counter. The counter range combined with the operating frequency will determine the maximum time resolution
achievable with the TC peripheral.
The TC can be count up or down. By default, the counter will operate in a continuous mode and count up, where the
counter will wrap to the zero when reaching the top value
When one of the compare/capture channels is used in compare mode, the TC can be used for waveform generation.
Upon a match between the counter and the value in one or more of the Compare/Capture Value registers (CCx), one or
more output pins on the device can be set to toggle. The CCx registers and the counter can thereby be used in frequency
generation and PWM generation.
Capture mode can be used to automatically capture the period and pulse width of signals.
27.6.2 Basic Operation
27.6.2.1 Initialization
The following register is enable-protected, meaning that it can only be written when the TC is disabled (CTRLA.ENABLE
is zero):
z
Control A register (CTRLA), except the Run Standby (RUNSTDBY), Enable (ENABLE) and Software Reset
(SWRST) bits
The following bits are enable-protected:
z
Event Action bits in the Event Control register (EVCTRL.EVACT)
Enable-protected bits in the CTRLA register can be written at the same time as CTRLA.ENABLE is written to one, but not
at the same time as CTRLA.ENABLE is written to zero.
Before the TC is enabled, it must be configured, as outlined by the following steps:
z
The TC bus clock (CLK_TCx_APB) must be enabled
z
The mode (8, 16 or 32 bits) of the TC must be selected in the TC Mode bit group in the Control A register
(CTRLA.MODE). The default mode is 16 bits
z
One of the wavegen modes must be selected in the Waveform Generation Operation bit group in the Control A
register (CTRLA.WAVEGEN)
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z
If the GCLK_TCx frequency used should be prescaled, this can be selected in the Prescaler bit group in the
Control A register (CTRLA.PRESCALER)
z
If the prescaler is used, one of the presync modes must be chosen in the Prescaler and Counter Synchronization
bit group in the Control A register (CTRLA.PRESYNC)
z
One-shot mode can be selected by writing a one to the One-Shot bit in the Control B Set register
(CTRLBSET.ONESHOT)
z
If the counter should count down from the top value, write a one to the Counter Direction bit in the Control B Set
register (CTRLBSET.DIR)
z
If capture operations are to be used, the individual channels must be enabled for capture in the Capture Channel x
Enable bit group in the Control C register (CTRLC.CPTEN)
z
The waveform output for individual channels can be inverted using the Waveform Output Invert Enable bit group in
the Control C register (CTRLC.INVEN)
27.6.2.2 Enabling, Disabling and Resetting
The TC is enabled by writing a one to the Enable bit in the Control A register (CTRLA.ENABLE). The TC is disabled by
writing a zero to CTRLA.ENABLE.
The TC is reset by writing a one to the Software Reset bit in the Control A register (CTRLA.SWRST). All registers in the
TC, except DBGCTRL, will be reset to their initial state, and the TC will be disabled. Refer to the CTRLA register for
details.
The TC should be disabled before the TC is reset to avoid undefined behavior.
27.6.2.3 Prescaler Selection
As seen in Figure 27-2, the GCLK_TC clock is fed into the internal prescaler. Prescaler output intervals from 1 to 1/1024
are available. For a complete list of available prescaler outputs, see the register description for the Prescaler bit group in
the Control A register (CTRLA.PRESCALER).
The prescaler consists of a counter that counts to the selected prescaler value, whereupon the output of the prescaler
toggles.
When the prescaler is set to a value greater than one, it is necessary to choose whether the prescaler should reset its
value to zero or continue counting from its current value on the occurrence of an overflow or underflow. It is also
necessary to choose whether the TC counter should wrap around on the next GCLK_TC clock pulse or the next
prescaled clock pulse (CLK_TC_CNT of Figure 27-2). To do this, use the Prescaler and Counter Synchronization bit
group in the Control A register (CTRLA.PRESYNC).
If the counter is set to count events from the event system, these will not pass through the prescaler, as seen in Figure
27-2.
Figure 27-2. Prescaler
PRESCALER
GCLK_TC
PRESCALER
GCLK_TC /
{1,2,4,8,64,256,1024 }
EVACT
CNT
EVENT
CLK_TC_CNT
27.6.2.4 TC Mode
The counter mode is selected with the TC Mode bit group in the Control A register (CTRLA.MODE). By default, the
counter is enabled in the 16-bit counter mode.
Three counter modes are available:
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z
COUNT8: The 8-bit TC has its own Period register (PER). This register is used to store the period value that can
be used as the top value for waveform generation.
z
COUNT16: This is the default counter mode. There is no dedicated period register in this mode.
z
COUNT32: This mode is achieved by pairing two 16-bit TC peripherals. This pairing is explained in “Clocks” on
page 443. The even-numbered TC instance will act as master to the odd-numbered TC peripheral, which will act
as a slave. The slave status of the slave is indicated by reading the Slave bit in the Status register
(STATUS.SLAVE). The registers of the slave will not reflect the registers of the 32-bit counter. Writing to any of the
slave registers will not affect the 32-bit counter. Normal access to the slave COUNT and CCx registers is not
allowed.
27.6.2.5 Counter Operations
The counter can be set to count up or down. When the counter is counting up and the top value is reached, the counter
will wrap around to zero on the next clock cycle. When counting down, the counter will wrap around to the top value when
zero is reached. In one-shot mode, the counter will stop counting after a wraparound occurs.
To set the counter to count down, write a one to the Direction bit in the Control B Set register (CTRLBSET.DIR). To count
up, write a one to the Direction bit in the Control B Clear register (CTRLBCLR.DIR).
Each time the counter reaches the top value or zero, it will set the Overflow Interrupt flag in the Interrupt Flag Status and
Clear register (INTFLAG.OVF). It is also possible to generate an event on overflow or underflow when the
Overflow/Underflow Event Output Enable bit in the Event Control register (EVCTRL.OVFEO) is one.
The counter value can be read from the Counter Value register (COUNT) or a new value can be written to the COUNT
register. Figure 27-3 gives an example of writing a new counter value. The COUNT value will always be zero when
starting the TC, unless some other value has been written to it or if the TC has been previously reloaded at TOP value,
because stopped while TC was counting down.
Figure 27-3. Counter Operation
Period(T)
Direction Change
COUNT written
"update "
COUNT
TOP
BOT
DIR
Stop Command
On the stop command, which can be evoked in the Command bit group in the Control B Set register (CTRLBSET.CMD),
the counter will retain its current value. All waveforms are cleared. The counter stops counting, and the Stop bit in the
Status register is set (STATUS.STOP).
Retrigger Command and Event Action
Retriggering can be evoked either as a software command, using the Retrigger command in the Control B Set register
(CTRLBSET.CMD), or as a retrigger event action, using the Event Action bit group in the Event Control register
(EVCTRL.EVACT).
When a retrigger is evoked while the counter is running, the counter will wrap to the top value or zero, depending on the
counter direction..
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When a retrigger is evoked with the counter stopped, the counter will continue counting from the value in the COUNT
register.
Note: When retrigger event action is configured and enabled as an event action, enabling the counter will not start the
counter. The counter will start at the next incoming event and restart on any following event.
Count Event Action
When the count event action is configured, every new incoming event will make the counter increment or decrement,
depending on the state of the direction bit (CTRLBSET.DIR).
Start Event Action
When the TC is configured with a start event action in the EVCTRL.EVACT bit group, enabling the TC does not make the
counter start; the start is postponed until the next input event or software retrigger action. When the counter is running,
an input event has not effect on the counter.
27.6.2.6 Compare Operations
When using the TC with the Compare/Capture Value registers (CCx) configured for compare operation, the counter
value is continuously compared to the values in the CCx registers. This can be used for timer or waveform operation.
Waveform Output Operations
The compare channels can be used for waveform generation on the corresponding I/O pins. To make the waveform
visible on the connected pin, the following requirements must be fulfilled:
z
Choose a waveform generation operation
z
Optionally, invert the waveform output by writing the corresponding Waveform Output Invert Enable bit in the
Control C register (CTRLC.INVx)
z
Enable the corresponding multiplexor in the PORT
The counter value is continuously compared with each CCx available. When a compare match occurs, the Match or
Capture Channel x interrupt flag in the Interrupt Flag Status and Clear register (INTFLAG.MCx) is set on the next zero-toone transition of CLK_TC_CNT (see Figure 27-4). An interrupt and/or event can be generated on such a condition when
INTENSET.MCx and/or EVCTRL.MCEOx is one.
One of four configurations in the Waveform Generation Operation bit group in the Control A register (CTRLA.WAVEGEN)
must be chosen to perform waveform generation. This will influence how the waveform is generated and impose
restrictions on the top value. The four configurations are:
z
Normal frequency (NFRQ)
z
Match frequency (MFRQ)
z
Normal PWM (NPWM)
z
Match PWM (MPWM)
When using NPWM or NFRQ, the top value is determined by the counter mode. In 8-bit mode, the Period register (PER)
is used as the top value and the top value can be changed by writing to the PER register. In 16- and 32-bit mode, the top
value is fixed to the maximum value of the counter.
Frequency Operation
When NFRQ is used, the waveform output (WO[x]) toggles every time CCx and the counter are equal, and the interrupt
flag corresponding to that channel will be set.
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Figure 27-4. Normal Frequency Operation
CNT written
"wraparound "
TOP
COUNT
CCx
Zero
WO[x]
When MFRQ is used, the value in CC0 will be used as the top value and WO[0] will toggle on every overflow/underflow.
Figure 27-5. Match Frequency Operation
Period (T)
Direction Change
COUNT written
" wraparound "
COUNT
TOP
Zero
WO[0]
PWM Operation
In PWM operation, the CCx registers control the duty cycle of the waveform generator output. Figure 27-6 shows how in
count-up the WO[x] output is set at a start or compare match between the COUNT value and the top value and cleared
on the compare match between the COUNT value and CCx register value.
In count-down the WO[x] output is cleared at start or compare match between the COUNT value and the top value and
set on the compare match between the COUNT value and CCx register value.
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Figure 27-6. Normal PWM Operation
Period(T)
CCn= BOT
CCn= TOP
"wraparound "
"match "
TOP
COUNT
CC n
Zero
WO[x]
In match operation, Compare/Capture register CC0 is used as the top value, in this case a negative pulse will appear on
WO[0] on every overflow/underflow.
The following equation is used to calculate the exact period for a single-slope PWM (RPWM_SS) waveform:
log ( TOP + 1 )
R PWM_SS = ----------------------------------log ( 2 )
f CLK_TC
f PWM_SS = -----------------------------N ( TOP + 1 )
where N represent the prescaler divider used (1, 2, 4, 8, 16, 64, 256, 1024).
Changing the Top Value
Changing the top value while the counter is running is possible. If a new top value is written when the counter value is
close to zero and counting down, the counter can be reloaded with the previous top value, due to synchronization delays.
If this happens, the counter will count one extra cycle before the new top value is used.
Figure 27-7. Changing the Top Value when Counting Down
MAX
" reload"
" write"
COUNT
ZERO
New TOP value
That is higher than
Current COUNT
New TOP value
That is Lower than
Current COUNT
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When counting up a change from a top value that is lower relative to the old top value can make the counter miss this
change if the counter value is larger than the new top value when the change occurred. This will make the counter count
to the max value. An example of this can be seen in Figure 27-8.
Figure 27-8. Changing the Top Value when Counting Up
Counter Wraparound
MAX
" wraparound "
" write "
COUNT
ZERO
New TOP value
That is higher than
Current COUNT
New TOP value
That is Lower than
Current COUNT
27.6.2.7 Capture Operations
To enable and use capture operations, the event line into the TC must be enabled using the TC Event Input bit in the
Event Control register (EVCTRL.TCEI). The capture channels to be used must also be enabled in the Capture Channel x
Enable bit group in the Control C register (CTRLC.CPTENx) before capture can be performed.
Event Capture Action
The compare/capture channels can be used as input capture channels to capture any event from the Event System and
give them a timestamp. Because all capture channels use the same event line, only one capture channel should be
enabled at a time when performing event capture.
Figure 27-9 shows four capture events for one capture channel.
Figure 27-9. Input Capture Timing
events
TOP
COUNT
ZERO
Capture 0
Capture 1
Capture 2
Capture 3
When the Capture Interrupt flag is set and a new capture event is detected, there is nowhere to store the new timestamp.
As a result, the Error Interrupt flag in the Interrupt Flag Status and Clear register (INTFLAG.ERR) is set.
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Period and Pulse-Width Capture Action
The TC can perform two input captures and restart the counter on one of the edges. This enables the TC to measure the
pulse width and period. This can be used to characterize the frequency and duty cycle of an input signal:
1
f = --T
tp
--dutyCycle = T
When using PPW event action, the period (T) will be captured into CC0 and the pulse width (tp) in CC1. In PWP event
action, the pulse width (tp) will be captured in CC0 and the period (T) in CC1.
Selecting PWP (pulse-width, period) or PPW (period, pulse-width) in the Event Action bit group in the Event Control
register (EVCTRL.EVACT) enables the TC to performs two capture actions, one on the rising edge and one on the falling
edge.
The TC Inverted Event Input in the Event Control register (EVCTRL.TCINV) is used to select whether the wraparound
should occur on the rising edge or the falling edge. If EVCTRL.TCINV is written to one, the wraparound will happen on
the falling edge. The event source to be captured must be an asynchronous event.
To fully characterize the frequency and duty cycle of the input signal, activate capture on CC0 and CC1 by writing 0x3 to
the Capture Channel x Enable bit group in the Control C register (CTRLC.CPTEN). When only one of these
measurements is required, the second channel can be used for other purposes.
The TC can detect capture overflow of the input capture channels. When the Capture Interrupt flag is set and a new
capture event is detected, there is nowhere to store the new timestamp. Asa result, INTFLAG.ERR is set.
27.6.3 Additional Features
27.6.3.1 One-Shot Operation
When one-shot operation is enabled, the counter automatically stops on the next counter overflow or underflow
condition. When the counter is stopped, STATUS.STOP is automatically set by hardware and the waveform outputs are
set to zero.
One-shot operation can be enabled by writing a one into the One-Shot bit in the Control B Set register
(CTRLBSET.ONESHOT) and disabled by writing a one to the One-Shot bit in the Control B Clear register
(CTRLBCLR.ONESHOT). When enabled, it will count until an overflow or underflow occurs. The one-shot operation can
be restarted with a retrigger command, a retrigger event or a start event.
When the counter restarts its operation, the Stop bit in the Status register (STATUS.STOP) is automatically cleared by
hardware.
27.6.4 Interrupts
The TC has the following interrupt sources:
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z Overflow/Underflow: OVF. This is an asynchronous interrupt and can be used to wake-up the device from any sleep
mode.
z Compare or Capture Channel: MCx. This is an asynchronous interrupt and can be used to wake-up the device from
any sleep mode.
z Capture Overflow Error: ERR. This is an asynchronous interrupt and can be used to wake-up the device from any
sleep mode.
z Synchronization Ready: SYNCRDY. This is an asynchronous interrupt and can be used to wake-up the device from
any sleep mode.
Each interrupt source has an interrupt flag associated with it. The interrupt flag in the Interrupt Flag Status and Clear
register (INTFLAG) is set when the interrupt condition occurs. Each interrupt can be individually enabled by writing a one
to the corresponding bit in the Interrupt Enable Set register (INTENSET), and disabled by writing a one to the
corresponding bit in the Interrupt Enable Clear register (INTENCLR). An interrupt request is generated when the interrupt
flag is set and the corresponding interrupt is enabled. The interrupt request remains active until the interrupt flag is
cleared, the interrupt is disabled or the TC is reset. See the INTFLAG register for details on how to clear interrupt flags.
The TC has one common interrupt request line for all the interrupt sources. The user must read the INTFLAG register to
determine which interrupt condition is present. Note that interrupts must be globally enabled for interrupt requests to be
generated. Refer to “Nested Vector Interrupt Controller” on page 30 for details.
27.6.5 Events
The TC can generate the following output events:
z
Overflow/Underflow (OVF)
z
Match or Capture (MC)
Writing a one to an Event Output bit in the Event Control register (EVCTRL.MCEO) enables the corresponding output
event. Writing a zero to this bit disables the corresponding output event.
To enable one of the following event actions, write to the Event Action bit group (EVCTRL.EVACT).
z
Start the counter
z
Retrigger counter
z
Increment or decrement counter (depends on counter direction)
z
Capture event
z
Capture period
z
Capture pulse width
Writing a one to the TC Event Input bit in the Event Control register (EVCTRL.TCEI) enables input events to the TC.
Writing a zero to this bit disables input events to the TC. Refer to “EVSYS – Event System” on page 313 for details on
configuring the Event System.
27.6.6 Sleep Mode Operation
The TC can be configured to operate in any sleep mode. To be able to run in standby, the RUNSTDBY bit in the Control
A register (CTRLA.RUNSTDBY) must be written to one. The TC can wake up the device using interrupts from any sleep
mode or perform actions through the Event System.
27.6.7 Synchronization
Due to the asynchronicity between CLK_TCx_APB and GCLK_TCx some registers must be synchronized when
accessed. A register can require:
z
Synchronization when written
z
Synchronization when read
z
Synchronization when written and read
z
No synchronization
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When executing an operation that requires synchronization, the Synchronization Busy bit in the Status
register(STATUS.SYNCBUSY) will be set immediately, and cleared when synchronization is complete. The
synchronization Ready interrupt can be used to signal when sync is complete. This can be accessed via the
Synchronization Ready Interrupt Flag in the Interrupt Flag Status and Clear register (INTFLAG.SYNCRDY).
If an operation that requires synchronization is executed while STATUS.SYNCBUSY is one, the bus will be stalled. All
operations will complete successfully, but the CPU will be stalled and interrupts will be pending as long as the bus is
stalled.
The following bits need synchronization when written:
z
Software Reset bit in the Control A register (CTRLA.SWRST)
z
Enable bit in the Control A register (CTRLA.ENABLE)
Write-synchronization is denoted by the Write-Synchronized property in the register description.
The following registers need synchronization when written:
z
Control B Clear register (CTRLBCLR)
z
Control B Set register (CTRLBSET)
z
Control C register (CTRLC)
z
Count Value register (COUNT)
z
Period Value register (PERIOD)
z
Compare/Capture Value registers (CCx)
Write-synchronization is denoted by the Write-Synchronized property in the register description.
The following registers need synchronization when read:
z
Control B Clear register (CTRLBCLR)
z
Control B Set register (CTRLBSET)
z
Control C register (CTRLC)
z
Count Value register (COUNT)
z
Period Value register (PERIOD)
z
Compare/Capture Value registers (CCx)
Read-synchronization is denoted by the Read-Synchronized property in the register description.
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27.7
Register Summary
Table 27-1. Register Summary – 8-Bit Mode Registers
Offset
Name
0x00
Bit Pos.
7:0
WAVEGEN[1:0]
MODE[1:0]
ENABLE
SWRST
CTRLA
0x01
PRESCSYNC[1:0]
15:8
0x02
RUNSTDBY
PRESCALER[2:0]
ADDR[4:0]
7:0
READREQ
0x03
15:8
RREQ
RCONT
0x04
CTRLBCLR
7:0
CMD[1:0]
ONESHOT
DIR
0x05
CTRLBSET
7:0
CMD[1:0]
ONESHOT
DIR
0x06
CTRLC
7:0
0x07
Reserved
0x08
DBGCTRL
0x09
Reserved
0x0A
CPTEN1
CPTEN0
INVEN1
7:0
INVEN0
DBGRUN
7:0
TCEI
TCINV
EVACT[2:0]
15:8
MCEO1
MCEO0
EVCTRL
0x0B
OVFEO
0x0C
INTENCLR
7:0
MC1
MC0
SYNCRDY
ERR
OVF
0x0D
INTENSET
7:0
MC1
MC0
SYNCRDY
ERR
OVF
0x0E
INTFLAG
7:0
MC1
MC0
SYNCRDY
ERR
OVF
0x0F
STATUS
7:0
SLAVE
STOP
0x10
COUNT
7:0
COUNT[7:0]
0x11
Reserved
0x12
Reserved
0x13
Reserved
0x14
PER
7:0
PER[7:0]
0x15
Reserved
0x16
Reserved
0x17
Reserved
0x18
CC0
7:0
CC[7:0]
0x19
CC1
7:0
CC[7:0]
0x1A
Reserved
0x1B
Reserved
0x1C
Reserved
0x1D
Reserved
0x1E
Reserved
0x1F
Reserved
SYNCBUSY
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Table 27-2. Register Summary – 16-Bit Mode Registers
Offset
Name
0x00
Bit Pos.
7:0
WAVEGEN[1:0]
MODE[1:0]
ENABLE
SWRST
CTRLA
0x01
PRESCSYNC[1:0]
15:8
0x02
RUNSTDBY
PRESCALER[2:0]
ADDR[4:0]
7:0
READREQ
0x03
15:8
RREQ
RCONT
0x04
CTRLBCLR
7:0
CMD[1:0]
ONESHOT
DIR
0x05
CTRLBSET
7:0
CMD[1:0]
ONESHOT
DIR
0x06
CTRLC
7:0
0x07
Reserved
0x08
DBGCTRL
0x09
Reserved
0x0A
CPTEN1
CPTEN0
INVEN1
7:0
INVEN0
DBGRUN
7:0
TCEI
TCINV
EVACT[2:0]
15:8
MCEO1
MCEO0
EVCTRL
0x0B
OVFEO
0x0C
INTENCLR
7:0
MC1
MC0
SYNCRDY
ERR
OVF
0x0D
INTENSET
7:0
MC1
MC0
SYNCRDY
ERR
OVF
0x0E
INTFLAG
7:0
MC1
MC0
SYNCRDY
ERR
OVF
0x0F
STATUS
7:0
SLAVE
STOP
0x10
SYNCBUSY
7:0
COUNT[7:0]
15:8
COUNT[15:8]
7:0
CC[7:0]
15:8
CC[15:8]
7:0
CC[7:0]
15:8
CC[15:8]
COUNT
0x11
0x12
Reserved
0x13
Reserved
0x14
Reserved
0x15
Reserved
0x16
Reserved
0x17
Reserved
0x18
CC0
0x19
0x1A
CC1
0x1B
0x1C
Reserved
0x1D
Reserved
0x1E
Reserved
0x1F
Reserved
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Table 27-3. Register Summary – 32-Bit Mode Registers
Offset
Name
0x00
Bit Pos.
7:0
WAVEGEN[1:0]
MODE[1:0]
ENABLE
SWRST
CTRLA
0x01
PRESCSYNC[1:0]
15:8
0x02
RUNSTDBY
PRESCALER[2:0]
ADDR[4:0]
7:0
READREQ
0x03
15:8
RREQ
RCONT
0x04
CTRLBCLR
7:0
CMD[1:0]
ONESHOT
DIR
0x05
CTRLBSET
7:0
CMD[1:0]
ONESHOT
DIR
0x06
CTRLC
7:0
0x07
Reserved
0x08
DBGCTRL
0x09
Reserved
0x0A
CPTEN1
CPTEN0
INVEN1
7:0
INVEN0
DBGRUN
7:0
TCEI
TCINV
EVACT[2:0]
15:8
MCEO1
MCEO0
EVCTRL
0x0B
OVFEO
0x0C
INTENCLR
7:0
MC1
MC0
SYNCRDY
ERR
OVF
0x0D
INTENSET
7:0
MC1
MC0
SYNCRDY
ERR
OVF
0x0E
INTFLAG
7:0
MC1
MC0
SYNCRDY
ERR
OVF
0x0F
STATUS
7:0
SLAVE
STOP
0x10
SYNCBUSY
7:0
COUNT[7:0]
15:8
COUNT[15:8]
0x12
23:16
COUNT[23:16]
0x13
31:24
COUNT[31:24]
7:0
CC[7:0]
15:8
CC[15:8]
0x1A
23:16
CC[23:16]
0x1B
31:24
CC[31:24]
0x1C
7:0
CC[7:0]
15:8
CC[15:8]
0x1E
23:16
CC[23:16]
0x1F
31:24
CC[31:24]
0x11
COUNT
0x14
Reserved
0x15
Reserved
0x16
Reserved
0x17
Reserved
0x18
0x19
CC0
0x1D
CC1
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27.8
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-Protected property in each individual register description. Refer to the “Register Access Protection” on page
443 and the “PAC – Peripheral Access Controller” on page 34 for details.
Some registers require synchronization when read and/or written. Synchronization is denoted by the Write-Synchronized
or Read-Synchronized property in each individual register description. Refer to “Synchronization” on page 452 for details.
Some registers are enable-protected, meaning they can only be written when the TC is disabled. Enable-protection is
denoted by the Enable-Protected property in each individual register description.
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27.8.1 Control A
Name:
CTRLA
Offset:
0x00
Reset:
0x0000
Property:
Write-Protected, Enable-Protected, Write-Synchronized
Bit
15
14
13
12
PRESCSYNC[1:0]
11
10
RUNSTDBY
9
8
PRESCALER[2:0]
Access
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ENABLE
SWRST
WAVEGEN[1:0]
MODE[1:0]
Access
R
R/W
R/W
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 15:14 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 13:12 – PRESCSYNC[1:0]: Prescaler and Counter Synchronization
These bits select whether on start or retrigger event the counter should wrap around on the next GCLK_TCx clock
or the next prescaled GCLK_TCx clock. It’s also possible to reset the prescaler.
The options are as shown in Table 27-4.
These bits are not synchronized.
Table 27-4. Prescaler and Counter Synchronization
Value
Name
Description
0x0
GCLK
Reload or reset the counter on next generic clock
0x1
PRESC
Reload or reset the counter on next prescaler clock
0x2
RESYNC
Reload or reset the counter on next generic clock. Reset the prescaler counter
0x3
-
Reserved
z
Bit 11 – RUNSTDBY: Run in Standby
This bit is used to keep the TC running in standby mode:
0: The TC is halted in standby.
1: The TC continues to run in standby.
This bit is not synchronized.
z
Bits 10:8 – PRESCALER[2:0]: Prescaler
These bits select the counter prescaler factor, as shown in Table 27-5.
These bits are not synchronized.
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Table 27-5. Prescaler
Value
Name
Description
0x0
DIV1
Prescaler: GCLK_TC
0x1
DIV2
Prescaler: GCLK_TC/2
0x2
DIV4
Prescaler: GCLK_TC/4
0x3
DIV8
Prescaler: GCLK_TC/8
0x4
DIV16
Prescaler: GCLK_TC/16
0x5
DIV64
Prescaler: GCLK_TC/64
0x6
DIV256
Prescaler: GCLK_TC/256
0x7
DIV1024
Prescaler: GCLK_TC/1024
z
Bit 7 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 6:5 – WAVEGEN[1:0]: Waveform Generation Operation
These bits select the waveform generation operation. They affect the top value, as shown in “Waveform Output
Operations” on page 447. It also controls whether frequency or PWM waveform generation should be used. How
these modes differ can also be seen from “Waveform Output Operations” on page 447.
These bits are not synchronized.
Table 27-6. Waveform Generation Operation
Value
Name
Operation
Top Value
Waveform Output
on Match
Waveform Output
on Wraparound
0x0
NFRQ
Normal frequency
PER(1)/Max
Toggle
No action
0x1
MFRQ
Match frequency
CC0
Toggle
No action
Clear when counting up
Set when counting up
Set when counting
down
Clear when counting
down
Clear when counting up
Set when counting up
Set when counting
down
Clear when counting
down
(1)
0x2
NPWM
Normal PWM
PER /Max
0x3
MPWM
Match PWM
CC0
Note:
1.
This depends on the TC mode. In 8-bit mode, the top value is the Period Value register (PER). In 16- and
32-bit mode it is the maximum value.
z
Bit 4 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 3:2 – MODE[1:0]: TC Mode
These bits select the TC mode, as shown in Table 27-7.
These bits are not synchronized.
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Table 27-7. TC Mode
Value
Name
Description
0x0
COUNT16
Counter in 16-bit mode
0x1
COUNT8
Counter in 8-bit mode
0x2
COUNT32
Counter in 32-bit mode
0x3
-
Reserved
z
Bit 1 – ENABLE: Enable
0: The peripheral is disabled.
1: The peripheral is enabled.
Due to synchronization, there is delay from writing CTRLA.ENABLE until the peripheral is enabled/disabled. The
value written to CTRLA.ENABLE will read back immediately, and the Synchronization Busy bit in the Status register (STATUS.SYNCBUSY) will be set. STATUS.SYNCBUSY will be cleared when the operation is complete.
z
Bit 0 – SWRST: Software Reset
0: There is no reset operation ongoing.
1: The reset operation is ongoing.
Writing a zero to this bit has no effect.
Writing a one to this bit resets all registers in the TC, except DBGCTRL, to their initial state, and the TC will be
disabled.
Writing a one to CTRLA.SWRST will always take precedence; all other writes in the same write-operation will be
discarded.
Due to synchronization there is a delay from writing CTRLA.SWRST until the reset is complete. CTRLA.SWRST
and STATUS.SYNCBUSY will both be cleared when the reset is complete.
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27.8.2 Read Request
For a detailed description of this register and its use, refer to the“Synchronization” on page 452.
Name:
READREQ
Offset:
0x02
Reset:
0x0000
Property:
-
Bit
15
14
13
12
11
10
9
8
RREQ
RCONT
Access
W
R/W
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ADDR[4:0]
Access
R
R
R
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bit 15 – RREQ: Read Request
Writing a zero to this bit has no effect.
This bit will always read as zero.
Writing a one to this bit requests synchronization of the register pointed to by the Address bit group (READREQ.ADDR) and sets the Synchronization Busy bit in the Status register (STATUS.SYNCBUSY).
z
Bit 14 – RCONT: Read Continuously
0: Continuous synchronization is disabled.
1: Continuous synchronization is enabled.
When continuous synchronization is enabled, the register pointed to by the Address bit group (READREQ.ADDR)
will be synchronized automatically every time the register is updated.
z
Bits 13:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 4:0 – ADDR[4:0]: Address
These bits select the offset of the register that needs read synchronization. In the TC, only COUNT and CCx are
available for read synchronization.
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27.8.3 Control B Clear
This register allows the user to change this register without doing a read-modify-write operation. Changes in this register
will also be reflected in the Control B Set (CTRLBSET) register.
Name:
CTRLBCLR
Offset:
0x04
Reset:
0x00
Property:
Write-Protected, Write-Synchronized, Read-Synchronized
Bit
7
6
5
4
3
2
CMD[1:0]
Access
ONESHOT
0
DIR
R/W
R/W
R
R
R
R/W
R
R/W
0
0
0
0
0
0
0
0
Reset
z
1
Bits 7:6 – CMD[1:0]: Command
These bits are used for software control of retriggering and stopping the TC. When a command has been executed, the CMD bit group will read back as zero. The commands are executed on the next prescaled GCLK_TC
clock cycle.
Writing a zero to one of these bits has no effect.
Writing a one to one of these bits will clear the pending command.
Table 27-8. Command
Value
Name
Description
0x0
NONE
No action
0x1
RETRIGGER
Force a start, restart or retrigger
0x2
STOP
Force a stop
0x3
-
Reserved
z
Bits 5:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – ONESHOT: One-Shot
This bit controls one-shot operation of the TC. When in one-shot mode, the TC will stop counting on the next overflow/underflow condition or a stop command.
0: The TC will wrap around and continue counting on an overflow/underflow condition.
1: The TC will wrap around and stop on the next underflow/overflow condition.
Writing a zero to this bit has no effect.
Writing a one to this bit will disable one-shot operation.
z
Bit 1 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 0 – DIR: Counter Direction
This bit is used to change the direction of the counter.
0: The timer/counter is counting up (incrementing).
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1: The timer/counter is counting down (decrementing).
Writing a zero to this bit has no effect.
Writing a one to this bit will make the counter count up.
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27.8.4 Control B Set
This register allows the user to change this register without doing a read-modify-write operation. Changes in this register
will also be reflected in the Control B Set (CTRLBCLR) register.
Name:
CTRLBSET
Offset:
0x05
Reset:
0x00
Property:
Write-Protected, Write-Synchronized, Read-Synchronized
Bit
7
6
5
4
3
CMD[1:0]
Access
1
ONESHOT
0
DIR
R/W
R/W
R
R
R
R/W
R
R/W
0
0
0
0
0
0
0
0
Reset
z
2
Bits 7:6 – CMD[1:0]: Command
These bits is used for software control of retriggering and stopping the TC. When a command has been executed,
the CMD bit group will be read back as zero. The commands are executed on the next prescaled GCLK_TC clock
cycle.
Writing a zero to one of these bits has no effect.
Writing a one to one of these bits will set a command.
Table 27-9. Command
Value
Name
Description
0x0
NONE
No action
0x1
RETRIGGER
Force a start, restart or retrigger
0x2
STOP
Force a stop
0x3
-
Reserved
z
Bits 5:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – ONESHOT: One-Shot
This bit controls one-shot operation of the TC. When active, the TC will stop counting on the next overflow/underflow condition or a stop command.
0: The TC will wrap around and continue counting on an overflow/underflow condition.
1: The timer/counter will wrap around and stop on the next underflow/overflow condition.
Writing a zero to this bit has no effect.
Writing a one to this bit will enable one-shot operation.
z
Bit 1 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 0 – DIR: Counter Direction
This bit is used to change the direction of the counter.
0: The timer/counter is counting up (incrementing).
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1: The timer/counter is counting down (decrementing).
Writing a zero to this bit has no effect
Writing a one to this bit will make the counter count down.
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27.8.5 Control C
Name:
CTRLC
Offset:
0x06
Reset:
0x00
Property:
Write-Protected, Write-Synchronized, Read-Synchronized
Bit
7
6
5
4
CPTEN1
CPTEN0
3
2
1
0
INVEN1
INVEN0
Access
R
R
R/W
R/W
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:6 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 5:4 – CPTENx: Capture Channel x Enable
These bits are used to select whether channel x is a capture or a compare channel.
Writing a one to CPTENx enables capture on channel x.
Writing a zero to CPTENx disables capture on channel x.
z
Bits 3:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 1:0 – INVENx: Waveform Output x Invert Enable
These bits are used to select inversion on the output of channel x.
Writing a one to INVENx inverts the output from WO[x].
Writing a zero to INVENx disables inversion of the output from WO[x].
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27.8.6 Debug Control
Name:
DBGCTRL
Offset:
0x08
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
DBGRUN
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – DBGRUN: Debug Run Mode
This bit is not affected by a software reset, and should not be changed by software while the TC is enabled.
0: The TC is halted when the device is halted in debug mode.
1: The TC continues normal operation when the device is halted in debug mode.
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27.8.7 Event Control
Name:
EVCTRL
Offset:
0x0A
Reset:
0x0000
Property:
Write-Protected, Enable-Protected
Bit
15
14
13
12
MCEO1
MCEO0
11
10
9
8
OVFEO
Access
R
R
R/W
R/W
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
TCEI
TCINV
EVACT[2:0]
Access
R
R
R/W
R/W
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 15:14 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 13:12 – MCEOx: Match or Capture Channel x Event Output Enable
These bits control whether event match or capture on channel x is enabled or not and generated for every match
or capture.
0: Match/Capture event on channel x is disabled and will not be generated.
1: Match/Capture event on channel x is enabled and will be generated for every compare/capture.
These bits are not enable-protected.
z
Bits 11:9 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 8 – OVFEO: Overflow/Underflow Event Output Enable
This bit is used to enable the Overflow/Underflow event. When enabled an event will be generated when the counter overflows/underflows.
0: Overflow/Underflow event is disabled and will not be generated.
1: Overflow/Underflow event is enabled and will be generated for every counter overflow/underflow.
This bit is not enable-protected.
z
Bits 7:6 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 5 – TCEI: TC Event Input
This bit is used to enable input events to the TC.
0: Incoming events are disabled.
1: Incoming events are enabled.
This bit is not enable-protected.
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z
Bit 4 – TCINV: TC Inverted Event Input
This bit inverts the input event source when used in PWP or PPW measurement.
0: Input event source is not inverted.
1: Input event source is inverted.
This bit is not enable-protected.
z
Bit 3 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 2:0 – EVACT[2:0]: Event Action
These bits define the event action the TC will perform on an event,as shown in Table 27-10.
Table 27-10. Event Action
Value
Name
Description
0x0
OFF
Event action disabled
0x1
RETRIGGER
Start, restart or retrigger TC on event
0x2
COUNT
Count on event
0x3
START
Start TC on event
0x4
-
Reserved
0x5
PPW
Period captured in CC0, pulse width in CC1
0x6
PWP
Period captured in CC1, pulse width in CC0
0x7
-
Reserved
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27.8.8 Interrupt Enable Clear
This register allows the user to enable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Set register (INTENSET).
Name:
INTENCLR
Offset:
0x0C
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
MC1
MC0
SYNCRDY
2
1
0
ERR
OVF
Access
R
R/W
R/W
R/W
R/W
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:6 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 5:4 – MCx: Match or Capture Channel x Interrupt Enable
0: The Match or Capture Channel x interrupt is disabled.
1: The Match or Capture Channel x interrupt is enabled.
Writing a zero to MCx has no effect.
Writing a one to MCx will clear the corresponding Match or Capture Channel x Interrupt Disable/Enable bit, which
disables the Match or Capture Channel x interrupt.
z
Bit 3 – SYNCRDY: Synchronization Ready Interrupt Enable
0: The Synchronization Ready interrupt is disabled.
1: The Synchronization Ready interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Synchronization Ready Interrupt Disable/Enable bit, which disables the Synchronization Ready interrupt.
z
Bit 2 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 1 – ERR: Error Interrupt Enable
0: The Error interrupt is disabled.
1: The Error interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Error Interrupt Disable/Enable bit, which disables the Error interrupt.
z
Bit 0 – OVF: Overflow Interrupt Enable
0: The Overflow interrupt is disabled.
1: The Overflow interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Overflow Interrupt Disable/Enable bit, which disables the Overflow interrupt.
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27.8.9 Interrupt Enable Set
This register allows the user to enable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Clear register (INTENCLR).
Name:
INTENSET
Offset:
0x0D
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
MC1
MC0
SYNCRDY
2
1
0
ERR
OVF
Access
R
R
R/W
R/W
R/W
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:6 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 5:4 – MCx: Match or Capture Channel x Interrupt Enable
0: The Match or Capture Channel x interrupt is disabled.
1: The Match or Capture Channel x interrupt is enabled.
Writing a zero to MCx has no effect.
Writing a one to MCx will set the corresponding Match or Capture Channel x Interrupt Enable bit, which enables
the Match or Capture Channel x interrupt.
z
Bit 3 – SYNCRDY: Synchronization Ready Interrupt Enable
0: The Synchronization Ready interrupt is disabled.
1: The Synchronization Ready interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Synchronization Ready Interrupt Disable/Enable bit, which enables the Synchronization Ready interrupt.
z
Bit 2 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 1 – ERR: Error Interrupt Enable
0: The Error interrupt is disabled.
1: The Error interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Error Interrupt bit, which enables the Error interrupt.
z
Bit 0 – OVF: Overflow Interrupt Enable
0: The Overflow interrupt is disabled.
1: The Overflow interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Overflow Interrupt Enable bit, which enables the Overflow interrupt.
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27.8.10 Interrupt Flag Status and Clear
Name:
INTFLAG
Offset:
0x0E
Reset:
0x00
Property:
-
Bit
7
6
5
4
3
2
MC1
MC0
SYNCRDY
1
0
ERR
OVF
Access
R
R
R/W
R/W
R/W
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:6 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 5:4 – MCx: Match or Capture Channel x
This flag is set on the next CLK_TC_CNT cycle after a match with the compare condition or once CCx register
contain a valid capture value, and will generate an interrupt request if the corresponding Match or Capture Channel x Interrupt Enable bit in the Interrupt Enable Set register (INTENSET.MCx) is one.
Writing a zero to one of these bits has no effect.
Writing a one to one of these bits will clear the corresponding Match or Capture Channel x interrupt flag
In capture mode, this flag is automatically cleared when CCx register is read.
z
Bit 3 – SYNCRDY: Synchronization Ready
This flag is set on a 1-to-0 transition of the Synchronization Busy bit in the Status register (STATUS.SYNCBUSY),
except when the transition is caused by an enable or software reset, and will generate an interrupt request if the
Synchronization Ready Interrupt Enable bit in the Interrupt Enable Set register (INTENSET.SYNCRDY) is one.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Synchronization Ready interrupt flag
z
Bit 2 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bit 1 – ERR: Error
This flag is set if a new capture occurs on a channel when the corresponding Match or Capture Channel x interrupt
flag is one, in which case there is nowhere to store the new capture.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Error interrupt flag.
z
Bit 0 – OVF: Overflow
This flag is set on the next CLK_TC_CNT cycle after an overflow condition occurs, and will generate an interrupt if
INTENCLR/SET.OVF is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Overflow interrupt flag.
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27.8.11 Status
Name:
STATUS
Offset:
0x0F
Reset:
0x08
Property:
-
Bit
7
6
5
SYNCBUSY
4
3
SLAVE
STOP
2
1
0
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
1
0
0
0
z
Bit 7 – SYNCBUSY: Synchronization Busy
This bit is cleared when the synchronization of registers between the clock domains is complete.
This bit is set when the synchronization of registers between clock domains is started.
z
Bits 6:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 4 – SLAVE: Slave
This bit is set when the even-numbered master TC is set to run in 32-bit mode. The odd-numbered TC will be the
slave.
z
Bit 3 – STOP: Stop
This bit is set when the TC is disabled, on a Stop command or on an overflow or underflow condition when the
One-Shot bit in the Control B Set register (CTRLBSET.ONESHOT) is one.
0: Counter is running.
1: Counter is stopped.
z
Bits 2:0 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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27.8.12 Counter Value
27.8.12.1 8-Bit Mode
Name:
COUNT
Offset:
0x10
Reset:
0x00
Property:
Write-Synchronized, Read-Synchronized
Bit
7
6
5
4
3
2
1
0
COUNT[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 7:0 – COUNT[7:0]: Counter Value
These bits contain the current counter value.
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27.8.12.2 16-Bit Mode
Name:
COUNT
Offset:
0x10
Reset:
0x0000
Property:
Write-Synchronized, Read-Synchronized
Bit
15
14
13
12
11
10
9
8
COUNT[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
COUNT[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 15:0 – COUNT[15:0]: Counter Value
These bits contain the current counter value.
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27.8.12.3 32-Bit Mode
Name:
COUNT
Offset:
0x10
Reset:
0x00000000
Property:
Write-Synchronized, Read-Synchronized
Bit
31
30
29
28
27
26
25
24
COUNT[31:24]
Access
Reset
Bit
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
23
22
21
20
19
18
17
16
COUNT[23:16]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
COUNT[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
COUNT[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31:0 – COUNT[31:0]: Counter Value
These bits contain the current counter value.
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27.8.13 Period Value
The Period Value register is available only in 8-bit TC mode. It is not available in 16-bit and 32-bit TC modes.
27.8.13.1 8-Bit Mode
Name:
PER
Offset:
0x14
Reset:
0xFF
Property:
Write-Synchronized, Read-Synchronized
Bit
7
6
5
4
3
2
1
0
PER[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
1
1
1
1
1
1
1
1
Bits 7:0 – PER[7:0]: Period Value
These bits contain the counter period value in 8-bitTC mode.
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27.8.14 Compare/Capture
27.8.14.1 8-Bit Mode
Name:
CCx
Offset:
0x18+i*0x1 [i=0..3]
Reset:
0x00
Property:
Write-Synchronized, Read-Synchronized
Bit
7
6
5
4
3
2
1
0
CC[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 7:0 – CC[7:0]: Compare/Capture Value
These bits contain the compare/capture value in 8-bit TC mode. In frequency or PWM waveform match operation
(CTRLA.WAVEGEN), the CC0 register is used as a period register.
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27.8.14.2 16-Bit Mode
Name:
CCx
Offset:
0x18+i*0x2 [i=0..3]
Reset:
0x0000
Property:
Write-Synchronized, Read-Synchronized
Bit
15
14
13
12
11
10
9
8
CC[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
CC[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 15:0 – CC[15:0]: Compare/Capture Value
These bits contain the compare/capture value in 16-bit TC mode. In frequency or PWM waveform match operation
(CTRLA.WAVEGEN), the CC0 register is used as a period register.
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27.8.14.3 32-Bit Mode
Name:
CCx
Offset:
0x18+i*0x4 [i=0..3]
Reset:
0x00000000
Property:
Write-Synchronized, Read-Synchronized
Bit
31
30
29
28
27
26
25
24
CC[31:24]
Access
Reset
Bit
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
23
22
21
20
19
18
17
16
CC[23:16]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
CC[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
CC[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 31:0 – CC[31:0]: Compare/Capture Value
These bits contain the compare/capture value in 32-bit TC mode. In frequency or PWM waveform match operation (CTRLA.WAVEGEN), the CC0 register is used as a period register.
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28.
28.1
ADC – Analog-to-Digital Converter
Overview
The Analog-to-Digital Converter (ADC) converts analog signals to digital values. The ADC has 12-bit resolution, and is
capable of converting up to 350ksps. The input selection is flexible, and both differential and single-ended measurements
can be performed. An optional gain stage is available to increase the dynamic range. In addition, several internal signal
inputs are available. The ADC can provide both signed and unsigned results.
ADC measurements can be started by either application software or an incoming event from another peripheral in the
device. ADC measurements can be started with predictable timing, and without software intervention.
Both internal and external reference voltages can be used.
An integrated temperature sensor is available for use with the ADC. The bandgap voltage as well as the scaled I/O and
core voltages can also be measured by the ADC.
The ADC has a compare function for accurate monitoring of user-defined thresholds, with minimum software intervention
required.
The ADC may be configured for 8-, 10- or 12-bit results, reducing the conversion time. ADC conversion results are
provided left- or right-adjusted, which eases calculation when the result is represented as a signed value.
28.2
Features
z 8-, 10- or 12-bit resolution
z Up to 350,000 samples per second (350ksps)
z Differential and single-ended inputs
z
Up to 32 analog inputs
z 25 positive and 10 negative, including internal and external
z Five internal inputs
z
Bandgap
Temperature sensor
z DAC
z Scaled core supply
z Scaled I/O supply
z
z 1/2x to 16x gain
z Single, continuous and pin-scan conversion options
z Windowing monitor with selectable channel
z Conversion range:
z
z
Vref [1v to VDDANA - 0.6V]
ADCx * GAIN [0V to -Vref ]
z Built-in internal reference and external reference options
z
Four bits for reference selection
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z Event-triggered conversion for accurate timing (one event input)
z Hardware gain and offset compensation
z Averaging and oversampling with decimation to support, up to 16-bit result
z Selectable sampling time
28.3
Block Diagram
Figure 28-1. ADC Block Diagram
CTRLA
WINCTRL
AVGCTRL
WINLT
SAMPCTRL
WINUT
EVCTRL
OFFSETCORR
SWTRIG
GAINCORR
INPUTCTRL
ADC0
...
ADCn
INT.SIG
ADC
POST
PROCESSING
RESULT
ADC0
...
ADCn
INT.SIG
INT1V
CTRLB
INTVCC
VREFA
VREFB
PRESCALER
REFCTRL
28.4
Signal Description
Signal Name
Type
Description
VREFA
Analog input
External reference voltage A
VREFB
Analog input
External reference voltage B
ADC[19..0](1)
Analog input
Analog input channels
Note:
1.
Refer to “Configuration Summary” on page 3 for details on exact number of analog input channels.
Refer to “I/O Multiplexing and Considerations” on page 16 for details on the pin mapping for this peripheral. One signal
can be mapped on several pins.
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28.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
28.5.1 I/O Lines
Using the ADC's I/O lines requires the I/O pins to be configured using the port configuration (PORT).
Refer to “PORT” on page 287 for details.
28.5.2 Power Management
The ADC will continue to operate in any sleep mode where the selected source clock is running. The ADC’s interrupts
can be used to wake up the device from sleep modes. The events can trigger other operations in the system without
exiting the sleep modes. Refer to “PM – Power Manager” on page 107 for details on the different sleep modes.
28.5.3 Clocks
The ADC bus clock (CLK_ADC_APB) can be enabled and disabled in the Power Manager, and the default state of
CLK_ADC_APB can be found in the Table 15-1.
A generic clock (GCLK_ADC) is required to clock the ADC. This clock must be configured and enabled in the Generic
Clock Controller (GCLK) before using the ADC. Refer “GCLK – Generic Clock Controller” on page 85 for details.
This generic clock is asynchronous to the bus clock (CLK_ADC_APB). Due to this asynchronicity, writes to certain
registers will require synchronization between the clock domains. Refer to “Synchronization” on page 492 for further
details.
28.5.4 DMA
Not applicable.
28.5.5 Interrupts
The interrupt request line is connected to the interrupt controller. Using ADC interrupts requires the interrupt controller to
be configured first. Refer to “Nested Vector Interrupt Controller” on page 30 for details.
28.5.6 Events
Events are connected to the Event System. Refer to “EVSYS – Event System” on page 313 for details.
28.5.7 Debug Operation
When the CPU is halted in debug mode, the ADC will halt normal operation. The ADC can be forced to continue
operation during debugging. Refer to the Debug Control register (DBGCTRL) for details.
28.5.8 Register Access Protection
All registers with write-access are optionally write-protected by the Peripheral Access Controller (PAC), except the
following register:
z
Interrupt Flag Status and Clear register (INTFLAG)
Write-protection is denoted by the Write-Protection property in the register description.
When the CPU is halted in debug mode or the CPU reset is extended, all write-protection is automatically disabled.
Write-protection does not apply for accesses through an external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
28.5.9 Analog Connections
I/O-pins AIN0 to AIN19 as well as the VREFA/VREFB reference voltage pin are analog inputs to the ADC.
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28.5.10 Calibration
The values BIAS_CAL and LINEARITY_CAL from the production test must be loaded from the NVM Software Calibration
Area into the ADC Calibration register (CALIB) by software to achieve specified accuracy.
Refer to “NVM Software Calibration Area Mapping” on page 28 for more details.
28.6
Functional Description
28.6.1 Principle of Operation
By default, the ADC provides results with 12-bit resolution. 8-bit or 10-bit results can be selected in order to reduce the
conversion time. The ADC has an oversampling with decimation option that can extend the resolution to 16 bits. The
input values can be either internal (e.g., internal temperature sensor) or external (connected I/O pins). The user can also
configure whether the conversion should be single-ended or differential.
28.6.2 Basic Operation
28.6.2.1 Initialization
Before enabling the ADC, the asynchronous clock source must be selected and enabled, and the ADC reference must be
configured. The first conversion after the reference is changed must not be used. All other configuration registers must
be stable during the conversion. The source for GCLK_ADC is selected and enabled in the System Controller
(SYSCTRL). Refer to “SYSCTRL – System Controller” on page 134 for more details.
When GCLK_ADC is enabled, the ADC can be enabled by writing a one to the Enable bit in the Control Register A
(CTRLA.ENABLE).
28.6.2.2 Enabling, Disabling and Reset
The ADC is enabled by writing a one to the Enable bit in the Control A register (CTRLA.ENABLE). The ADC is disabled
by writing a zero to CTRLA.ENABLE.
The ADC is reset by writing a one to the Software Reset bit in the Control A register (CTRLA.SWRST). All registers in the
ADC, except DBGCTRL, will be reset to their initial state, and the ADC will be disabled. Refer to the CTRLA register for
details.
The ADC must be disabled before it is reset.
28.6.2.3 Basic Operation
In the most basic configuration, the ADC sample values from the configured internal or external sources (INPUTCTRL
register). The rate of the conversion is dependent on the combination of the GCLK_ADC frequency and the clock
prescaler.
To convert analog values to digital values, the ADC needs first to be initialized, as described in “Initialization” on page
484. Data conversion can be started either manually, by writing a one to the Start bit in the Software Trigger register
(SWTRIG.START), or automatically, by configuring an automatic trigger to initiate the conversions. A free-running mode
could be used to continuously convert an input channel. There is no need for a trigger to start the conversion. It will start
automatically at the end of previous conversion.
The automatic trigger can be configured to trigger on many different conditions.
The result of the conversion is stored in the Result register (RESULT) as it becomes available, overwriting the result from
the previous conversion.
To avoid data loss if more than one channel is enabled, the conversion result must be read as it becomes available
(INTFLAG.RESRDY). Failing to do so will result in an overrun error condition, indicated by the OVERRUN bit in the
Interrupt Flag Status and Clear register (INTFLAG.OVERRUN).
To use an interrupt handler, the corresponding bit in the Interrupt Enable Set register (INTENSET) must be written to
one.
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28.6.3 Prescaler
The ADC is clocked by GCLK_ADC. There is also a prescaler in the ADC to enable conversion at lower clock rates.
Refer to CTRLB for details on prescaler settings.
Figure 28-2. ADC Prescaler
DIV512
DIV256
DIV128
DIV64
DIV32
DIV16
DIV8
9-BIT PRESCALER
DIV4
GCLK_ADC
CTRLB.PRESCALER[2:0]
CLK_ADC
The propagation delay of an ADC measurement depends on the selected mode and is given by:
z
Single-shot mode:
Resolution
1 + ---------------------------- + DelayGain
2
PropagationDelay = -------------------------------------------------------------------------f CLK – ADC
z
Free-running mode:
Resolution
---------------------------- + DelayGain
2
PropagationDelay = ---------------------------------------------------------------f CLK – ADC
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Table 28-1. Delay Gain
Delay Gain (in CLK_ADC Period)
Free-running mode
Name
Single shot mode
INTPUTCTRL.GAIN[3:0]
Differential Mode
Single-Ended Mode
Differential mode
Single-Ended mode
1X
0x0
0
0
0
1
2X
0x1
0
1
0.5
1.5
4X
0x2
1
1
1
2
8X
0x3
1
2
1.5
2.5
16X
0x4
2
2
2
3
Reserved
0x5 ... 0xE
Reserved
Reserved
Reserved
Reserved
DIV2
0xF
0
1
0.5
1.5
28.6.4 ADC Resolution
The ADC supports 8-bit, 10-bit and 12-bit resolutions. Resolution can be changed by writing the Resolution bit group in
the Control B register (CTRLB.RESSEL). After a reset, the resolution is set to 12 bits by default.
28.6.5 Differential and Single-Ended Conversions
The ADC has two conversion options: differential and single-ended. When measuring signals where the positive input is
always at a higher voltage than the negative input, the single-ended conversion should be used in order to have full 12bit resolution in the conversion, which has only positive values. The negative input must be connected to ground. This
ground could be the internal GND, IOGND or an external ground connected to a pin. Refer to INPUTCTRL for selection
details. If the positive input may go below the negative input, creating some negative results, the differential mode should
be used in order to get correct results. The configuration of the conversion is done in the Differential Mode bit in the
Control B register (CTRLB.DIFFMODE). These two types of conversion could be run in single mode or in free-running
mode. When set up in free-running mode, an ADC input will continuously sample and do new conversions. The
INTFLAG.RESRDY bit will be set at the end of each conversion.
28.6.5.1 Conversion Timing
Figure 28-3 shows the ADC timing for a single conversion without gain. The writing of the ADC Start Conversion bit
(SWTRIG.START) or Start Conversion Event In bit (EVCTRL.STARTEI) must occur at least one CLK_ADC_APB cycle
before the CLK_ADC cycle on which the conversion starts. The input channel is sampled in the first half CLK_ADC
period. The sampling time can be increased by using the Sampling Time Length bit group in the Sampling Time Control
register (SAMPCTRL.SAMPLEN). Refer to Figure 28-4 for example on increased sampling time.
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Figure 28-3. ADC Timing for One Conversion in Differential Mode without Gain
1
2
3
4
5
6
7
8
CLK_ ADC
START
SAMPLE
INT
Converting Bit
MS B
10
9
8
7
6
5
4
3
2
1
LS B
Figure 28-4. ADC Timing for One Conversion in Differential Mode without Gain, but with Increased Sampling Time
1
2
3
4
5
6
7
8
9
10
11
CLK_ ADC
START
SAMPLE
INT
Converting Bit
MS B
10
9
8
7
6
5
4
3
2
1
LS B
Figure 28-5. ADC Timing for Free Running in Differential Mode without Gain
2
1
3
4
5
6
7
9
8
10
11
12
13
6
4
2
0
14
15
16
8
6
CLK_ ADC
START
SAMPLE
INT
Converting Bit
11
10
9
8
7
6
5
4
3
2
1
0
11
10
9
8
7
5
3
1
11
10
9
7
5
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Figure 28-6. ADC Timing for One Conversion in Single-Ended Mode without Gain
1
2
3
4
5
6
7
8
9
10
11
CLK_ADC
START
SAMPLE
AMPLIFY
INT
Converting Bit
MS B
10
9
8
7
6
5
4
3
2
1
LS B
Figure 28-7. ADC Timing for Free Running in Single-Ended Mode without Gain
2
1
3
4
5
6
7
9
8
10
11
12
13
14
9
7
5
3
1
15
16
CLK_ADC
START
SAMPLE
AMPLIFY
INT
Converting Bit
11
10
9
8
7
6
5
4
3
2
1
0
11
10
8
6
4
2
0
11
10
28.6.6 Accumulation
The result from multiple consecutive conversions can be accumulated. The number of samples to be accumulated is
specified by writing to the Number of Samples to be Collected field in the Average Control register
(AVGCTRL.SAMPLENUM) as described in Table . When accumulating more than 16 samples, the result will be too large
for the 16-bit RESULT register. To avoid overflow, the result is shifted right automatically to fit within the 16 available bits.
The number of automatic right shifts are specified in Table . Note that to be able to perform the accumulation of two or
more samples, the Conversion Result Resolution field in the Control B register (CTRLB.RESSEL) must be written to one.
Table 28-2. Accumulation
Number of
Accumulated Samples
AVGCTRL.
SAMPLENUM
Intermediate
Result Precision
Number of Automatic
Right Shifts
Final Result
Precision
Automatic
Division Factor
1
0x0
12 bits
0
12 bits
0
2
0x1
13 bits
0
13 bits
0
4
0x2
14 bits
0
14 bits
0
8
0x3
15 bits
0
15 bits
0
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Table 28-2. Accumulation (Continued)
Number of
Accumulated Samples
AVGCTRL.
SAMPLENUM
Intermediate
Result Precision
Number of Automatic
Right Shifts
Final Result
Precision
Automatic
Division Factor
16
0x4
16 bits
0
16 bits
0
32
0x5
17 bits
1
16 bits
2
64
0x6
18 bits
2
16 bits
4
128
0x7
19 bits
3
16 bits
8
256
0x8
20 bits
4
16 bits
16
512
0x9
21 bits
5
16 bits
32
1024
0xA
22 bits
6
16 bits
64
Reserved
0xB –0xF
12 bits
12 bits
0
28.6.7 Averaging
Averaging is a feature that increases the sample accuracy, though at the cost of reduced sample rate. This feature is
suitable when operating in noisy conditions. Averaging is done by accumulating m samples, as described in
“Accumulation” on page 488, and divide the result by m. The averaged result is available in the RESULT register. The
number of samples to be accumulated is specified by writing to AVGCTRL.SAMPLENUM as described in Table . The
division is obtained by a combination of the automatic right shift described above, and an additional right shift that must
be specified by writing to the Adjusting Result/Division Coefficient field in AVGCTRL (AVGCTRL.ADJRES) as described
in Table . Note that to be able to perform the averaging of two or more samples, the Conversion Result Resolution field in
the Control B register (CTRLB.RESSEL) must be written to one.
1
Averaging AVGCTRL.SAMPLENUM samples will reduce the effective sample rate by ------------------------------------------------------------------- .
AVGCTRL.SAMPLENUM
When the required average is reached, the INTFLAG.RESRDY bit is set.
Table 28-3. Averaging
Number of
Accumulated
Samples
AVGCTRL.
SAMPLENUM
Intermediate
Result
Precision
Number of
Automatic
Right Shifts
Division
Factor
AVGCTRL.
ADJRES
1
0x0
12 bits
0
1
0x0
2
0x1
13
0
2
0x1
4
0x2
14
0
4
8
0x3
15
0
16
0x4
16
32
0x5
64
Total
Number
of Right
Shifts
Final
Result
Precision
Automatic
Division
Factor
12 bits
0
1
12 bits
0
0x2
2
12 bits
0
8
0x3
3
12 bits
0
0
16
0x4
4
12 bits
0
17
1
16
0x4
5
12 bits
2
0x6
18
2
16
0x4
6
12 bits
4
128
0x7
19
3
16
0x4
7
12 bits
8
256
0x8
20
4
16
0x4
8
12 bits
16
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Table 28-3. Averaging (Continued)
Number of
Accumulated
Samples
AVGCTRL.
ADJRES
Total
Number
of Right
Shifts
Final
Result
Precision
Automatic
Division
Factor
16
0x4
9
12 bits
32
16
0x4
10
12 bits
64
12 bits
0
AVGCTRL.
SAMPLENUM
Intermediate
Result
Precision
Number of
Automatic
Right Shifts
Division
Factor
512
0x9
21
5
1024
0xA
22
6
Reserved
0xB –0xF
0x0
28.6.8 Oversampling and Decimation
By using oversampling and decimation, the ADC resolution can be increased from 12 bits to up to 16 bits. To increase
the resolution by n bits, 4n samples must be accumulated. The result must then be shifted right by n bits. This right shift is
a combination of the automatic right shift and the value written to AVGCTRL.ADJRES. To obtain the correct resolution,
the ADJRES must be configured as described in the table below. This method will result in n bit extra LSB resolution.
Table 28-4. Configuration Required for Oversampling and Decimation
AVGCTRL.SAMPLENUM[3:0]
Number of
Automatic Right
Shifts
AVGCTRL.ADJRES[2:0]
41 = 4
0x2
0
0x1
42 = 16
0x4
0
0x2
Result
Resolution
Number of Samples
to Average
13 bits
14 bits
3
15 bits
4 = 64
0x6
2
0x1
16 bits
44 = 256
0x8
4
0x0
28.6.9 Window Monitor
The window monitor allows the conversion result to be compared to some predefined threshold values. Supported
modes are selected by writing the Window Monitor Mode bit group in the Window Monitor Control register
(WINCTRL.WINMODE[2:0]). Thresholds are given by writing the Window Monitor Lower Threshold register (WINLT) and
Window Monitor Upper Threshold register (WINUT).
If differential input is selected, the WINLT and WINUT are evaluated as signed values. Otherwise they are evaluated as
unsigned values.
Another important point is that the significant WINLT and WINUT bits are given by the precision selected in the
Conversion Result Resolution bit group in the Control B register (CTRLB.RESSEL). This means that if 8-bit mode is
selected, only the eight lower bits will be considered. In addition, in differential mode, the eighth bit will be considered as
the sign bit even if the ninth bit is zero.
The INTFLAG.WINMON interrupt flag will be set if the conversion result matches the window monitor condition.
28.6.10 Offset and Gain Correction
Inherent gain and offset errors affect the absolute accuracy of the ADC. The offset error is defined as the deviation of the
actual ADC’s transfer function from an ideal straight line at zero input voltage. The offset error cancellation is handled by
the Offset Correction register (OFFSETCORR). The offset correction value is subtracted from the converted data before
writing the Result register (RESULT). The gain error is defined as the deviation of the last output step’s midpoint from the
ideal straight line, after compensating for offset error. The gain error cancellation is handled by the Gain Correction
register (GAINCORR). To correct these two errors, the Digital Correction Logic Enabled bit in the Control B register
(CTRLB.CORREN) must be written to one.
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Offset and gain error compensation results are both calculated according to:
Result = ( Conversion value – OFFSETCORR ) ⋅ GAINCORR
In single conversion, a latency of 13 GCLK_ADC is added to the availability of the final result. Since the correction time is
always less than the propagation delay, this latency appears in free-running mode only during the first conversion. After
that, a new conversion will be initialized when a conversion completes. All other conversion results are available at the
defined sampling rate.
Figure 28-8. ADC Timing Correction Enabled
START
CONV0
CONV1
CORR0
CONV2
CORR1
CONV3
CORR2
CORR3
28.6.11 Interrupts
The ADC has the following interrupt sources:
z
Result Conversion Ready: RESRDY. This is an asynchronous interrupt and can be used to wake-up the device
from any sleep mode
z
Overrun: OVERRUN
z
Window Monitor: WINMON. This is an asynchronous interrupt and can be used to wake-up the device from any
sleep mode
z
Synchronization Ready: SYNCRDY. This is an asynchronous interrupt and can be used to wake-up the device
from any sleep mode
Each interrupt source has an interrupt flag associated with it. The interrupt flag in the Interrupt Flag Status and Clear
register (INTFLAG) is set when the interrupt condition occurs. Each interrupt can be individually enabled by writing a one
to the corresponding bit in the Interrupt Enable Set register (INTENSET), and disabled by writing a one to the
corresponding bit in the Interrupt Enable Clear register (INTENCLR) register. An interrupt request is generated when the
interrupt flag is set and the corresponding interrupt is enabled. The interrupt request remains active until the interrupt flag
is cleared, the interrupt is disabled or the peripheral is reset. An interrupt flag is cleared by writing a one to the
corresponding bit in the INTFLAG register. Each peripheral can have one interrupt request line per interrupt source or
one common interrupt request line for all the interrupt sources. This is device dependent.
Refer to “Nested Vector Interrupt Controller” on page 30 for details. If the peripheral has one common interrupt request
line for all the interrupt sources, the user must read the INTFLAG register to determine which interrupt condition is
present.
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28.6.12 Events
The peripheral can generate the following output events:
z
Result Ready (RESRDY)
z
Window Monitor (WINMON)
Output events must be enabled to be generated. Writing a one to an Event Output bit in the Event Control register
(EVCTRL.xxEO) enables the corresponding output event. Writing a zero to this bit disables the corresponding output
event. The events must be correctly routed in the Event System. Refer to “EVSYS – Event System” on page 313 for
details.
The peripheral can take the following actions on an input event:
z
ADC start conversion (START)
z
ADC conversion flush (FLUSH)
Input events must be enabled for the corresponding action to be taken on any input event. Writing a one to an Event
Input bit in the Event Control register (EVCTRL.xxEI) enables the corresponding action on the input event. Writing a zero
to this bit disables the corresponding action on the input event. Note that if several events are connected to the
peripheral, the enabled action will be taken on any of the incoming events. The events must be correctly routed in the
Event System. Refer to “EVSYS – Event System” on page 313 for details.
28.6.13 Sleep Mode Operation
The Run in Standby bit in the Control A register (CTRLA.RUNSTDBY) controls the behavior of the ADC during standby
sleep mode. When the bit is zero, the ADC is disabled during sleep, but maintains its current configuration. When
the bit is one, the ADC continues to operate during sleep. Note that when RUNSTDBY is zero, the analog
blocks are powered off for the lowest power consumption. This necessitates a start-up time delay when the system
returns from sleep.
When RUNSTDBY is one, any enabled ADC interrupt source can wake up the CPU. While the CPU is sleeping, ADC
conversion can only be triggered by events.
28.6.14 Synchronization
Due to the asynchronicity between CLK_ADC_APB and GCLK_ADC, some registers must be synchronized when
accessed. A register can require:
z
Synchronization when written
z
Synchronization when read
z
Synchronization when written and read
z
No synchronization
When executing an operation that requires synchronization, the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set immediately, and cleared when synchronization is complete. The Synchronization
Ready interrupt can be used to signal when synchronization is complete.
If an operation that requires synchronization is executed while STATUS.SYNCBUSY is one, the bus will be stalled. All
operations will complete successfully, but the CPU will be stalled and interrupts will be pending as long as the bus is
stalled.
The following bits need synchronization when written:
z
Software Reset bit in the Control A register (CTRLA.SWRST)
z
Enable bit in the Control A register (CTRLA.ENABLE)
The following registers need synchronization when written:
z
Control B (CTRLB)
z
Software Trigger (SWTRIG)
z
Window Monitor Control (WINCTRL)
z
Input Control (INPUTCTRL)
z
Window Upper/Lower Threshold (WINUT/WINLT)
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Write-synchronization is denoted by the Write-Synchronized property in the register description.
The following registers need synchronization when read:
z
Software Trigger (SWTRIG)
z
Input Control (INPUTCTRL)
z
Result (RESULT)
Read-synchronization is denoted by the Read-Synchronized property in the register description.
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28.7
Register Summary
Offset
Name
Bit pos.
0x00
CTRLA
7:0
0x01
REFCTRL
7:0
0x02
AVGCTRL
7:0
0x03
SAMPCTRL
7:0
0x04
RUNSTDBY
ENABLE
SWRST
REFSEL[3:0]
REFCOMP
ADJRES[2:0]
SAMPLENUM[3:0]
SAMPLEN[5:0]
RESSEL[1:0]
7:0
CORREN
FREERUN
LEFTADJ
DIFFMODE
CTRLB
0x05
0x06
Reserved
0x07
Reserved
0x08
WINCTRL
0x09
Reserved
0x0A
Reserved
0x0B
Reserved
0x0C
SWTRIG
0x0D
Reserved
0x0E
Reserved
0x0F
Reserved
0x10
0x11
15:8
PRESCALER[2:0]
7:0
WINMODE[2:0]
7:0
START
7:0
MUXPOS[4:0]
15:8
MUXNEG[4:0]
FLUSH
INPUTCTRL
0x12
23:16
0x13
31:24
INPUTOFFSET[3:0]
INPUTSCAN[3:0]
GAIN[3:0]
WINMONEO
SYNCEI
STARTEI
WINMON
OVERRUN
RESRDY
SYNCRDY
WINMON
OVERRUN
RESRDY
SYNCRDY
WINMON
OVERRUN
RESRDY
EVCTRL
0x15
Reserved
0x16
INTENCLR
7:0
SYNCRDY
0x17
INTENSET
7:0
0x18
INTFLAG
7:0
0x19
STATUS
7:0
0x1A
7:0
RESRDYEO
0x14
SYNCBUSY
7:0
RESULT[7:0]
15:8
RESULT[15:8]
7:0
WINLT[7:0]
15:8
WINLT[15:8]
7:0
WINUT[7:0]
15:8
WINUT[15:8]
RESULT
0x1B
0x1C
WINLT
0x1D
0x1E
Reserved
0x1F
Reserved
0x20
WINUT
0x21
0x22
Reserved
0x23
Reserved
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Offset
Name
0x24
Bit pos.
7:0
GAINCORR[7:0]
GAINCORR
0x25
GAINCORR[11:8]
15:8
0x26
7:0
OFFSETCORR[7:0]
OFFSETCORR
0x27
OFFSETCORR[11:8]
15:8
0x28
7:0
LINEARITY_CAL[7:0]
CALIB
0x29
0x2A
15:8
DBGCTRL
7:0
BIAS_CAL[2:0]
DBGRUN
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28.8
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-Protected property in each individual register description. Refer to “Register Access Protection” on page 483
for details.
Some registers require synchronization when read and/or written. Synchronization is denoted by the Write-Synchronized
or the Read-Synchronized property in each individual register description. Refer to “Synchronization” on page 492 for
details.
Some registers are enable-protected, meaning they can be written only when the ADC is disabled. Enable-protection is
denoted by the Enable-Protected property in each individual register description.
28.8.1 Control A
Name:
CTRLA
Offset:
0x00
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
RUNSTDBY
ENABLE
SWRST
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – RUNSTDBY: Run in Standby
This bit indicates whether the ADC will continue running in standby sleep mode or not:
0: The ADC is halted during standby sleep mode.
1: The ADC continues normal operation during standby sleep mode.
z
Bit 1 – ENABLE: Enable
0: The ADC is disabled.
1: The ADC is enabled.
Due to synchronization, there is a delay from writing CTRLA.ENABLE until the peripheral is enabled/disabled. The
value written to CTRL.ENABLE will read back immediately and the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set. STATUS.SYNCBUSY will be cleared when the operation is complete.
z
Bit 0 – SWRST: Software Reset
0: There is no reset operation ongoing.
1: The reset operation is ongoing.
Writing a zero to this bit has no effect.
Writing a one to this bit resets all registers in the ADC, except DBGCTRL, to their initial state, and the ADC will be
disabled.
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Writing a one to CTRL.SWRST will always take precedence, meaning that all other writes in the same write-operation will be discarded.
Due to synchronization, there is a delay from writing CTRLA.SWRST until the reset is complete. CTRLA.SWRST
and STATUS.SYNCBUSY will both be cleared when the reset is complete.
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28.8.2 Reference Control
Name:
REFCTRL
Offset:
0x01
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
REFCOMP
Access
Reset
z
1
0
REFSEL[3:0]
R/W
R
R
R
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bit 7 – REFCOMP: Reference Buffer Offset Compensation Enable
The accuracy of the gain stage can be increased by enabling the reference buffer offset compensation. This will
decrease the input impedance and thus increase the start-up time of the reference.
0: Reference buffer offset compensation is disabled.
1: Reference buffer offset compensation is enabled.
z
Bits 6:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 3:0 – REFSEL[3:0]: Reference Selection
These bits select the reference for the ADC according to Table 28-5.
Table 28-5. Reference Selection
Value
Name
Description
0x0
INT1V
1.0V voltage reference
0x1
INTVCC0
1/1.48 VDDANA
0x2
INTVCC1
1/2 VDDANA (only for VDDANA > 2.0V)
0x3
VREFA
External reference
0x4
VREFB
External reference
0x5-0xF
Reserved
Reserved
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28.8.3 Average Control
Name:
AVGCTRL
Offset:
0x02
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
ADJRES[2:0]
2
1
0
SAMPLENUM[3:0]
Access
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bit 7 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 6:4 – ADJRES[2:0]: Adjusting Result / Division Coefficient
These bits define the division coefficient in 2n steps.
z
Bits 3:0 – SAMPLENUM[3:0]: Number of Samples to be Collected
These bits define how many samples should be added together.The result will be available in the Result register
(RESULT). Note: if the result width increases, CTRLB.RESSEL must be changed.
Table 28-6. Number of Samples to be Collected
Value
Name
Description
0x0
1 sample
0x1
2 samples
0x2
4 samples
0x3
8 samples
0x4
16 samples
0x5
32 samples
0x6
64 samples
0x7
128 samples
0x8
256 samples
0x9
512 samples
0xA
1024 samples
0xB-0xF
Reserved
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28.8.4 Sampling Time Control
Name:
SAMPCTRL
Offset:
0x03
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
SAMPLEN[5:0]
Access
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:6 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 5:0 – SAMPLEN[5:0]: Sampling Time Length
These bits control the ADC sampling time in number of half CLK_ADC cycles, depending of the prescaler value,
thus controlling the ADC input impedance. Sampling time is set according to the equation:
CLK ADC
Sampling time = ( SAMPLEN + 1 ) ⋅ ⎛ ----------------------⎞
⎝
⎠
2
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28.8.5 Control B
Name:
CTRLB
Offset:
0x04
Reset:
0x0000
Property:
Write-Synchronized, Write-Protected
Bit
15
14
13
12
11
10
9
8
PRESCALER[2:0]
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
CORREN
FREERUN
LEFTADJ
DIFFMODE
RESSEL[1:0]
Access
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 15:11 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 10:8 – PRESCALER[2:0]: Prescaler Configuration
These bits define the ADC clock relative to the peripheral clock according to Table 28-7. These bits can only be
written while the ADC is disabled.
Table 28-7. Prescaler Configuration
Value
Name
Description
0x0
DIV4
Peripheral clock divided by 4
0x1
DIV8
Peripheral clock divided by 8
0x2
DIV16
Peripheral clock divided by 16
0x3
DIV32
Peripheral clock divided by 32
0x4
DIV64
Peripheral clock divided by 64
0x5
DIV128
Peripheral clock divided by 128
0x6
DIV256
Peripheral clock divided by 256
0x7
DIV512
Peripheral clock divided by 512
z
Bits 7:6 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 5:4 – RESSEL[1:0]: Conversion Result Resolution
These bits define whether the ADC completes the conversion at 12-, 10- or 8-bit result resolution. These bits can
be written only while the ADC is disabled.
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Table 28-8. Conversion Result Resolution
Value
Name
Description
0x0
12BIT
12-bit result
0x1
16BIT
For averaging mode output
0x2
10BIT
10-bit result
0x3
8BIT
8-bit result
z
Bit 3 – CORREN: Digital Correction Logic Enabled
0: Disable the digital result correction.
1: Enable the digital result correction. The ADC conversion result in the RESULT register is then corrected for gain
and offset based on the values in the GAINCAL and OFFSETCAL registers. Conversion time will be increased by
X cycles according to the value in the Offset Correction Value bit group in the Offset Correction register.
This bit can be changed only while the ADC is disabled.
z
Bit 2 – FREERUN: Free Running Mode
0: The ADC run is single conversion mode.
1: The ADC is in free running mode and a new conversion will be initiated when a previous conversion completes.
This bit can be changed only while the ADC is disabled.
z
Bit 1 – LEFTADJ: Left-Adjusted Result
0: The ADC conversion result is right-adjusted in the RESULT register.
1: The ADC conversion result is left-adjusted in the RESULT register. The high byte of the 12-bit result will be
present in the upper part of the result register. Writing this bit to zero (default) will right-adjust the value in the
RESULT register.
This bit can be changed only while the ADC is disabled.
z
Bit 0 – DIFFMODE: Differential Mode
0: The ADC is running in singled-ended mode.
1: The ADC is running in differential mode. In this mode, the voltage difference between the MUXPOS and MUXNEG inputs will be converted by the ADC.
This bit can be changed only while the ADC is disabled.
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28.8.6 Window Monitor Control
Name:
WINCTRL
Offset:
0x08
Reset:
0x00
Property:
Write-Synchronized, Write-Protected
Bit
7
6
5
4
3
2
1
0
WINMODE[2:0]
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 2:0 – WINMODE[2:0]: Window Monitor Mode
These bits enable and define the window monitor mode. Table 28-9 shows the mode selections.
Table 28-9. Window Monitor Mode
Value
Name
Description
0x0
No window mode (default)
0x1
Mode 1: RESULT > WINLT
0x2
Mode 2: RESULT < WINUT
0x3
Mode 3: WINLT < RESULT < WINUT
0x4
Mode 4:!(WINLT < RESULT < WINUT)
0x5-0x7
Reserved
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28.8.7 Software Trigger
Name:
SWTRIG
Offset:
0x0C
Reset:
0x00
Property:
Write-Synchronized, Write-Protected
Bit
7
6
5
4
3
2
1
0
START
FLUSH
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – START: ADC Start Conversion
0: The ADC will not start a conversion.
1: The ADC will start a conversion. The bit is cleared by hardware when the conversion has started. Setting this bit
when it is already set has no effect.
Writing this bit to zero will have no effect.
z
Bit 0 – FLUSH: ADC Conversion Flush
0: No flush action.
1: The ADC pipeline will be flushed. A flush will restart the ADC clock on the next peripheral clock edge, and all
conversions in progress will be aborted and lost. This bit is cleared until the ADC has been flushed.
After the flush, the ADC will resume where it left off; i.e., if a conversion was pending, the ADC will start a new
conversion.
Writing this bit to zero will have no effect.
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28.8.8 Input Control
Name:
INPUTCTRL
Offset:
0x10
Reset:
0x00000000
Property:
Write-Synchronized, Write-Protected
Bit
31
30
29
28
27
26
25
24
GAIN[3:0]
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
23
22
21
20
19
18
17
16
Bit
INPUTOFFSET[3:0]
Access
INPUTSCAN[3:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
MUXNEG[4:0]
Access
R
R
R
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
MUXPOS[4:0]
Access
R
R
R
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 31:28 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 27:24 – GAIN[3:0]: Gain Factor Selection
These bits set the gain factor of the ADC gain stage according to the values shown in Table 28-10.
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Table 28-10. Gain Factor Selection
Value
Name
Description
0x0
1X
1x
0x1
2X
2x
0x2
4X
4x
0x3
8X
8x
0x4
16X
16x
0x5-0xE
–
Reserved
0xF
DIV2
1/2x
z
Bits 23:20 – INPUTOFFSET[3:0]: Positive Mux Setting Offset
The pin scan is enabled when INPUTSCAN != 0. Writing these bits to a value other than zero causes the first conversion triggered to be converted using a positive input equal to MUXPOS + INPUTOFFSET. Setting this register
to zero causes the first conversion to use a positive input equal to MUXPOS.
After a conversion, the INPUTOFFSET register will be incremented by one, causing the next conversion to be
done with the positive input equal to MUXPOS + INPUTOFFSET. The sum of MUXPOS and INPUTOFFSET gives
the input that is actually converted.
z
Bits 19:16 – INPUTSCAN[3:0]: Number of Input Channels Included in Scan
This register gives the number of input sources included in the pin scan. The number of input sources included is
INPUTSCAN + 1. The input channels included are in the range from MUXPOS + INPUTOFFSET to MUXPOS +
INPUTOFFSET + INPUTSCAN.
The range of the scan mode must not exceed the number of input channels available on the device.
z
Bits 15:13 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 12:8 – MUXNEG[4:0]: Negative Mux Input Selection
These bits define the Mux selection for the negative ADC input. Table 28-11 shows the possible input selections.
Table 28-11. Negative Mux Input Selection
Value
Name
Description
0x00
PIN0
ADC AIN0 pin
0x01
PIN1
ADC AIN1 pin
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Table 28-11. Negative Mux Input Selection (Continued)
Value
Name
Description
0x02
PIN2
ADC AIN2 pin
0x03
PIN3
ADC AIN3 pin
0x04
PIN4
ADC AIN4 pin
0x05
PIN5
ADC AIN5 pin
0x06
PIN6
ADC AIN6 pin
0x07
PIN7
ADC AIN7 pin
0x08-0x17
–
Reserved
0x18
GND
Internal ground
0x19
IOGND
I/O ground
0x1A-0x1F
–
Reserved
z
Bits 7:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 4:0 – MUXPOS[4:0]: Positive Mux Input Selection
These bits define the Mux selection for the positive ADC input. Table 28-12 shows the possible input selections. If
the internal bandgap voltage or temperature sensor input channel is selected, then the Sampling Time Length bit
group in the Sampling Control register must be written.
Table 28-12. Positive Mux Input Selection
MUXPOS[4:0]
Group configuration
Description
0x00
PIN0
ADC AIN0 pin
0x01
PIN1
ADC AIN1 pin
0x02
PIN2
ADC AIN2 pin
0x03
PIN3
ADC AIN3 pin
0x04
PIN4
ADC AIN4 pin
0x05
PIN5
ADC AIN5 pin
0x06
PIN6
ADC AIN6 pin
0x07
PIN7
ADC AIN7 pin
0x08
PIN8
ADC AIN8 pin
0x09
PIN9
ADC AIN9 pin
0x0A
PIN10
ADC AIN10 pin
0x0B
PIN11
ADC AIN11 pin
0x0C
PIN12
ADC AIN12 pin
0x0D
PIN13
ADC AIN13 pin
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Table 28-12. Positive Mux Input Selection (Continued)
MUXPOS[4:0]
Group configuration
Description
0x0E
PIN14
ADC AIN14 pin
0x0F
PIN15
ADC AIN15 pin
0x10
PIN16
ADC AIN16 pin
0x11
PIN17
ADC AIN17 pin
0x12
PIN18
ADC AIN18 pin
0x13
PIN19
ADC AIN19 pin
0x14-0x17
Reserved
0x18
TEMP
Temperature reference
0x19
BANDGAP
Bandgap voltage
0x1A
SCALEDCOREVCC
1/4 scaled core supply
0x1B
SCALEDIOVCC
1/4 scaled I/O supply
0x1C
DAC
DAC output
0x1D-0x1F
Reserved
Atmel | SMART SAM D20 [DATASHEET]
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28.8.9 Event Control
Name:
EVCTRL
Offset:
0x14
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
WINMONEO
RESRDYEO
3
2
1
0
SYNCEI
STARTEI
Access
R
R
R/W
R/W
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:6 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 5 – WINMONEO: Window Monitor Event Out
This bit indicates whether the Window Monitor event output is enabled or not and an output event will be generated when the window monitor detects something.
0: Window Monitor event output is disabled and an event will not be generated.
1: Window Monitor event output is enabled and an event will be generated.
z
Bit 4 – RESRDYEO: Result Ready Event Out
This bit indicates whether the Result Ready event output is enabled or not and an output event will be generated
when the conversion result is available.
0: Result Ready event output is disabled and an event will not be generated.
1: Result Ready event output is enabled and an event will be generated.
z
Bits 3:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – SYNCEI: Synchronization Event In
0: A flush and new conversion will not be triggered on any incoming event.
1: A flush and new conversion will be triggered on any incoming event.
z
Bit 0 – STARTEI: Start Conversion Event In
0: A new conversion will not be triggered on any incoming event.
1: A new conversion will be triggered on any incoming event.
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28.8.10 Interrupt Enable Clear
This register allows the user to disable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Set register (INTENSET).
Name:
INTENCLR
Offset:
0x16
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
SYNCRDY
WINMON
OVERRUN
RESRDY
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 3 – SYNCRDY: Synchronization Ready Interrupt Enable
0: The Synchronization Ready interrupt is disabled.
1: The Synchronization Ready interrupt is enabled, and an interrupt request will be generated when the Synchronization Ready interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Synchronization Ready Interrupt Enable bit and the corresponding interrupt
request.
z
Bit 2 – WINMON: Window Monitor Interrupt Enable
0: The window monitor interrupt is disabled.
1: The window monitor interrupt is enabled, and an interrupt request will be generated when the Window Monitor
interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Window Monitor Interrupt Enable bit and the corresponding interrupt request.
z
Bit 1 – OVERRUN: Overrun Interrupt Enable
0: The Overrun interrupt is disabled.
1: The Overrun interrupt is enabled, and an interrupt request will be generated when the Overrun interrupt flag is
set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Overrun Interrupt Enable bit and the corresponding interrupt request.
z
Bit 0 – RESRDY: Result Ready Interrupt Enable
0: The Result Ready interrupt is disabled.
1: The Result Ready interrupt is enabled, and an interrupt request will be generated when the Result Ready interrupt flag is set.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Result Ready Interrupt Enable bit and the corresponding interrupt request.
Atmel | SMART SAM D20 [DATASHEET]
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28.8.11 Interrupt Enable Set
This register allows the user to enable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Clear register (INTENCLR).
Name:
INTENSET
Offset:
0x17
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
SYNCRDY
WINMON
OVERRUN
RESRDY
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 3 – SYNCRDY: Synchronization Ready Interrupt Enable
0: The Synchronization Ready interrupt is disabled.
1: The Synchronization Ready interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Synchronization Ready Interrupt Enable bit, which enables the Synchronization
Ready interrupt.
z
Bit 2 – WINMON: Window Monitor Interrupt Enable
0: The Window Monitor interrupt is disabled.
1: The Window Monitor interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Window Monitor Interrupt bit and enable the Window Monitor interrupt.
z
Bit 1 – OVERRUN: Overrun Interrupt Enable
0: The Overrun interrupt is disabled.
1: The Overrun interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Overrun Interrupt bit and enable the Overrun interrupt.
z
Bit 0 – RESRDY: Result Ready Interrupt Enable
0: The Result Ready interrupt is disabled.
1: The Result Ready interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Result Ready Interrupt bit and enable the Result Ready interrupt.
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28.8.12 Interrupt Flag Status and Clear
Name:
INTFLAG
Offset:
0x18
Reset:
0x00
Property:
–
Bit
7
6
5
4
3
2
1
0
SYNCRDY
WINMON
OVERRUN
RESRDY
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 3 – SYNCRDY: Synchronization Ready
This flag is cleared by writing a one to the flag.
This flag is set on a one-to-zero transition of the Synchronization Busy bit in the Status register (STATUS.SYNCBUSY), except when caused by an enable or software reset, and will generate an interrupt request if
INTENCLR/SET.SYNCRDY is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Synchronization Ready interrupt flag.
z
Bit 2 – WINMON: Window Monitor
This flag is cleared by writing a one to the flag or by reading the RESULT register.
This flag is set on the next GCLK_ADC cycle after a match with the window monitor condition, and an interrupt
request will be generated if INTENCLR/SET.WINMON is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Window Monitor interrupt flag.
z
Bit 1 – OVERRUN: Overrun
This flag is cleared by writing a one to the flag.
This flag is set if RESULT is written before the previous value has been read by CPU, and an interrupt request will
be generated if INTENCLR/SET.OVERRUN is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Overrun interrupt flag.
z
Bit 0 – RESRDY: Result Ready
This flag is cleared by writing a one to the flag or by reading the RESULT register.
This flag is set when the conversion result is available, and an interrupt will be generated if INTENCLR/SET.RESRDY is one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Result Ready interrupt flag.
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28.8.13 Status
Name:
STATUS
Offset:
0x19
Reset:
0x00
Property:
–
Bit
7
6
5
4
3
2
1
0
SYNCBUSY
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bit 7 – SYNCBUSY: Synchronization Busy
This bit is cleared when the synchronization of registers between the clock domains is complete.
This bit is set when the synchronization of registers between clock domains is started.
z
Bits 6:0 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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28.8.14 Result
Name:
RESULT
Offset:
0x1A
Reset:
0x0000
Property:
Read-Synchronized
Bit
15
14
13
12
11
10
9
8
RESULT[15:8]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
RESULT[7:0]
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bits 15:0 – RESULT[15:0]: Result Conversion Value
These bits will hold up to a 16-bit ADC result, depending on the configuration.
In single-ended without averaging mode, the ADC conversion will produce a 12-bit result, which can be left- or
right-shifted, depending on the setting of CTRLB.LEFTADJ.
If the result is left-adjusted (CTRLB.LEFTADJ), the high byte of the result will be in bit position [15:8], while the
remaining 4 bits of the result will be placed in bit locations [7:4]. This can be used only if an 8-bit result is required;
i.e., one can read only the high byte of the entire 16-bit register.
If the result is not left-adjusted (CTRLB.LEFTADJ) and no oversampling is used, the result will be available in bit
locations [11:0], and the result is then 12 bits long.
If oversampling is used, the result will be located in bit locations [15:0], depending on the settings of the Average
Control register (AVGCTRL).
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28.8.15 Window Monitor Lower Threshold
Name:
WINLT
Offset:
0x1C
Reset:
0x0000
Property:
Write-Synchronized, Write-Protected
Bit
15
14
13
12
11
10
9
8
WINLT[15:8]
Acces
s
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
WINLT[7:0]
Acces
s
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 15:0 – WINLT[15:0]: Window Lower Threshold
If the window monitor is enabled, these bits define the lower threshold value.
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28.8.16 Window Monitor Upper Threshold
Name:
WINUT
Offset:
0x20
Reset:
0x0000
Property:
Write-Synchronized, Write-Protected
Bit
15
14
13
12
11
10
9
8
WINUT[15:8]
Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
WINUT[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 15:0 – WINUT[15:0]: Window Upper Threshold
If the window monitor is enabled, these bits define the upper threshold value.
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28.8.17 Gain Correction
Name:
GAINCORR
Offset:
0x24
Reset:
0x0000
Property:
Write-Protected
Bit
15
14
13
12
11
10
9
8
GAINCORR[11:8]
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
GAINCORR[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 15:12 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 11:0 – GAINCORR[11:0]: Gain Correction Value
If the CTRLB.CORREN bit is one, these bits define how the ADC conversion result is compensated for gain error
before being written to the result register. The gain correction is a fractional value, a 1-bit integer plus an 11-bit
fraction, and therefore ½ <= GAINCORR < 2. GAINCORR values range from 0.10000000000 to 1.11111111111.
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28.8.18 Offset Correction
Name:
OFFSETCORR
Offset:
0x26
Reset:
0x0000
Property:
Write-Protected
Bit
15
14
13
12
11
10
9
8
OFFSETCORR[11:8]
Access
R
R
R
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
OFFSETCORR[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 15:12 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 11:0 – OFFSETCORR[11:0]: Offset Correction Value
If the CTRLB.CORREN bit is one, these bits define how the ADC conversion result is compensated for offset error
before being written to the Result register. This OFFSETCORR value is in two’s complement format.
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28.8.19 Calibration
Name:
CALIB
Offset:
0x28
Reset:
0x0000
Property:
Write-Protected
Bit
15
14
13
12
11
10
9
8
BIAS_CAL[2:0]
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
LINEARITY_CAL[7:0]
Access
Reset
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
z
Bits 15:11 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 10:8 – BIAS_CAL[2:0]: Bias Calibration Value
This value from production test must be loaded from the NVM software calibration area into the CALIB register by
software to achieve the specified accuracy.
The value must be copied only, and must not be changed.
z
Bits 7:0 – LINEARITY_CAL[7:0]: Linearity Calibration Value
This value from production test must be loaded from the NVM software calibration area into the CALIB register by
software to achieve the specified accuracy.
The value must be copied only, and must not be changed.
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28.8.20 Debug Control
Name:
DBGCTRL
Offset:
0x2A
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
DBGRUN
Access
R
R
R
R
R
R
R
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 0 – DBGRUN: Debug Run
0: The ADC is halted during debug mode.
1: The ADC continues normal operation during debug mode.
This bit can be changed only while the ADC is disabled.
This bit should be written only while a conversion is not ongoing.
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29.
29.1
AC – Analog Comparators
Overview
The Analog Comparator (AC) supports two individual comparators. Each comparator (COMP) compares the voltage
levels on two inputs, and provides a digital output based on this comparison. Each comparator may be configured to
generate interrupt requests and/or peripheral events upon several different combinations of input change.
Hysteresis and propagation delay are two important properties of the comparators; dynamic behavior. Both parameters
may be adjusted to achieve the optimal operation for each application.
The input selection includes four shared analog port pins and several internal signals. Each comparator output state can
also be output on a pin for use by external devices.
The comparators are always grouped in pairs on each port. The AC module may implement one pair. These are called
Comparator 0 (COMP0) and Comparator 1 (COMP1). They have identical behaviors, but separate control registers. The
pair can be set in window mode to compare a signal to a voltage range instead of a single voltage level.
29.2
Features
z Two individual comparators
z Selectable propagation delay versus current consumption
z Selectable hysteresis
z
On/Off
z Analog comparator outputs available on pins
z
Asynchronous or synchronous
z Flexible input selection
z
Four pins selectable for positive or negative inputs
Ground (for zero crossing)
z Bandgap reference voltage
z 64-level programmable VDDANA scaler per comparator
z DAC
z
z Interrupt generation on:
z
Rising or falling edge
Toggle
z End of comparison
z
z Window function interrupt generation on:
z
Signal above window
Signal inside window
z Signal below window
z Signal outside window
z
z Event generation on:
z
z
Comparator output
Window function inside/outside window
z Optional digital filter on comparator output
z Low-power option
z
Single-shot support
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29.3
Block Diagram
Figure 29-1. Analog Comparator Block Diagram
AIN0
+
CMP0
COMP0
AIN1
-
HYSTERESIS
VDDANA
SCALER
INTERRUPTS
ENABLE
INTERRUPT MODE
DAC
COMPCTRLn
WINCTRL
ENABLE
BANDGAP
EVENTS
GCLK_AC
HYSTERESIS
+
AIN2
INTERRUPT
SENSITIVITY
CONTROL
&
WINDOW
FUNCTION
CMP1
COMP1
AIN3
29.4
-
Signal Description
Signal Name
Type
Description
AIN[3..0]
Analog input
Comparator inputs
CMP[1..0]
Digital output
Comparator outputs
Refer to “I/O Multiplexing and Considerations” on page 16 for details on the pin mapping for this peripheral. One signal
can be mapped on several pins.
29.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
29.5.1 I/O Lines
Using the AC’s I/O lines requires the I/O pins to be configured. Refer to the PORT chapter for details.
Refer to “PORT” on page 287 for details.
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29.5.2 Power Management
The AC will continue to operate in any sleep mode where the selected source clock is running. The AC’s interrupts can
be used to wake up the device from sleep modes. The events can trigger other operations in the system without exiting
sleep modes. Refer to “PM – Power Manager” on page 107 for details on the different sleep modes.
29.5.3 Clocks
The AC bus clock (CLK_AC_APB) can be enabled and disabled in the Power Manager, and the default state of the
CLK_AC_APB can be found in the Peripheral Clock Masking section of “PM – Power Manager” on page 107.
Two generic clocks (GCLK_AC_DIG and GCLK_AC_ANA) are used by the AC. The digital clock (GCLK_AC_DIG) is
required to provide the sampling rate for the comparators, while the analog clock (GCLK_AC_ANA) is required for lowvoltage operation (VDDANA < 2.5V) to ensure that the resistance of the analog input multiplexors remains low. These
clocks must be configured and enabled in the Generic Clock Controller before using the peripheral.
Refer to “GCLK – Generic Clock Controller” on page 85 for details.
These generic clocks are asynchronous to the CLK_AC_APB clock. Due to this asynchronicity, writes to certain registers
will require synchronization between the clock domains. Refer to “Synchronization” on page 531 for further details.
29.5.4 Interrupts
The interrupt request line is connected to the Interrupt Controller. Using the AC interrupts requires the Interrupt Controller
to be configured first. Refer to “Nested Vector Interrupt Controller” on page 30 for details.
29.5.5 Events
The events are connected to the Event System. Using the events requires the Event System to be configured first. Refer
to “EVSYS – Event System” on page 313 for details.
29.5.6 Debug Operation
When the CPU is halted in debug mode, the peripheral continues normal operation. If the peripheral is configured in a
way that requires it to be periodically serviced by the CPU through interrupts or similar, improper operation or data loss
may result during debugging.
29.5.7 Register Access Protection
All registers with write-access are optionally write-protected by the Peripheral Access Controller (PAC), except the
following registers:
z
Control B register (CTRLB)
z
Interrupt Flag register (INTFLAG)
Write-protection is denoted by the Write-Protected property in the register description.
Write-protection does not apply for accesses through an external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
29.5.8 Analog Connections
Each comparator has up to four I/O pins that can be used as analog inputs. Each pair of comparators shares the same
four pins. These pins must be configured for analog operation before using them as comparator inputs.
Any internal reference source, such as a bandgap reference voltage or the DAC, must be configured and enabled prior to
its use as a comparator input.
29.5.9 Other Dependencies
Not applicable.
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29.6
Functional Description
29.6.1 Principle of Operation
Each comparator has one positive input and one negative input. Each positive input may be chosen from a selection of
analog input pins. Each negative input may be chosen from a selection of analog input pins or internal inputs, such as a
bandgap reference voltage. The digital output from the comparator is one when the difference between the positive and
the negative input voltage is positive, and zero otherwise.
The individual comparators can be used independently (normal mode) or grouped in pairs to generate a window
comparison (window mode).
29.6.2 Basic Operation
29.6.2.1 Initialization
Before enabling the AC, the input and output events must be configured in the Event Control register (EVCTRL). These
settings cannot be changed while the AC is enabled.
Each individual comparator must also be configured by its respective Comparator Control register (Comparator Control
n) before that comparator is enabled. These settings cannot be changed while the comparator is enabled.
z
Select the desired measurement mode with COMPCTRLx.SINGLE. See “Starting a Comparison” on page
524 for more details
z
Select the desired hysteresis with COMPCTRLx.HYST. See “Input Hysteresis” on page 528 for more details
z
Select the comparator speed versus power with COMPCTRLx.SPEED. See “Propagation Delay vs. Power
Consumption” on page 528 for more details
z
Select the interrupt source with COMPCTRLx.INTSEL
z
Select the positive and negative input sources with the COMPCTRLx.MUXPOS and
COMPCTRLx.MUXNEG bits. See section “Selecting Comparator Inputs” on page 526 for more details
z
Select the filtering option with COMPCTRLx.FLEN
29.6.2.2 Enabling, Disabling and Resetting
The AC is enabled by writing a one to the Enable bit in the Control A register (CTRLA.ENABLE). The individual
comparators must be also enabled by writing a one to the Enable bit in the Comparator x Control registers
(COMPCTRLx.ENABLE). The AC is disabled by writing a zero to CTRLA.ENABLE. This will also disable the individual
comparators, but will not clear their COMPCTRLx.ENABLE bits.
The AC is reset by writing a one to the Software Reset bit in the Control A register (CTRLA.SWRST). All registers in the
AC, except DEBUG, will be reset to their initial state, and the AC will be disabled. Refer to the CTRLA register for details.
29.6.2.3 Starting a Comparison
Each comparator channel can be in one of two different measurement modes, determined by the Single bit in the
Comparator x Control register (COMPCTRLx.SINGLE):
z
Continuous measurement
z
Single-shot
After being enabled, a start-up delay is required before the result of the comparison is ready. This start-up time is
measured automatically to account for environmental changes, such as temperature or voltage supply level, and is
specified in “Electrical Characteristics” on page 571.
During the start-up time, the COMP output is not available. If the supply voltage is below 2.5V, the start-up time is also
dependent on the voltage doubler. If the supply voltage is guaranteed to be above 2.5V, the voltage doubler can be
disabled by writing the Low-Power Mux bit in the Control A register (CTRLA.LPMUX) to one.
The comparator can be configured to generate interrupts when the output toggles, when the output changes from zero to
one (rising edge), when the output changes from one to zero (falling edge) or at the end of the comparison. An end-ofcomparison interrupt can be used with the single-shot mode to chain further events in the system, regardless of the state
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of the comparator outputs. The interrupt mode is set by the Interrupt Selection bit group in the Comparator Control
register (COMPCTRLx.INTSEL). Events are generated using the comparator output state, regardless of whether the
interrupt is enabled or not.
Continuous Measurement
Continuous measurement is selected by writing COMPCTRLx.SINGLE to zero. In continuous mode, the comparator is
continuously enabled and performing comparisons. This ensures that the result of the latest comparison is always
available in the Current State bit in the Status A register (STATUSA.STATEx). After the start-up time has passed, a
comparison is done and STATUSA is updated. The Comparator x Ready bit in the Status B register
(STATUSB.READYx) is set, and the appropriate peripheral events and interrupts are also generated. New comparisons
are performed continuously until the COMPCTRLx.ENABLE bit is written to zero. The start-up time applies only to the
first comparison.
In continuous operation, edge detection of the comparator output for interrupts is done by comparing the current and
previous sample. The sampling rate is the GCLK_AC_DIG frequency. An example of continuous measurement is shown
in Figure 29-2.
Figure 29-2. Continuous Measurement Example
GCLK_AC
Write ‘1’
COMPCTRLx.ENABLE
2-3 cycles
tSTARTUP
STATUSB.READYx
Sampled
Comparator Output
For low-power operation, comparisons can be performed during sleep modes without a clock. The comparator is enabled
continuously, and changes in the state of the comparator are detected asynchronously. When a toggle occurs, the Power
Manager will start GCLK_AC_DIG to register the appropriate peripheral events and interrupts. The GCLK_AC_DIG clock
is then disabled again automatically, unless configured to wake up the system from sleep.
Single-Shot
Single-shot operation is selected by writing COMPCTRLx.SINGLE to one. During single-shot operation, the comparator
is normally idle. The user starts a single comparison by writing a one to the respective Start Comparison bit in the writeonly Control B register (CTRLB.STARTx). The comparator is enabled, and after the start-up time has passed, a single
comparison is done and STATUSA is updated. Appropriate peripheral events and interrupts are also generated. No new
comparisons will be performed.
Writing a one to CTRLB.STARTx also clears the Comparator x Ready bit in the Status B register (STATUSB.READYx).
STATUSB.READYx is set automatically by hardware when the single comparison has completed. To remove the need
for polling, an additional means of starting the comparison is also available. A read of the Status C register (STATUSC)
will start a comparison on all comparators currently configured for single-shot operation. The read will stall the bus until
all enabled comparators are ready. If a comparator is already busy with a comparison, the read will stall until the current
comparison is compete, and a new comparison will not be started.
A single-shot measurement can also be triggered by the Event System. Writing a one to the Comparator x Event Input bit
in the Event Control Register (EVCTRL.COMPEIx) enables triggering on incoming peripheral events. Each comparator
can be triggered independently by separate events. Event-triggered operation is similar to user-triggered operation; the
difference is that a peripheral event from another hardware module causes the hardware to automatically start the
comparison and clear STATUSB.READYx.
To detect an edge of the comparator output in single-shot operation for the purpose of interrupts, the result of the current
measurement is compared with the result of the previous measurement (one sampling period earlier). An example of
single-shot operation is shown in Figure 29-3.
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Figure 29-3. Single-Shot Example
GCLK_AC
Write ‘1’
CTRLB.STARTx
Write ‘1’
2-3 cycles
2-3 cycles
tSTARTUP
tSTARTUP
STATUSB.READYx
Sampled
Comparator Output
For low-power operation, event-triggered measurements can be performed during sleep modes. When the event occurs,
the Power Manager will start GCLK_AC_DIG. The comparator is enabled, and after the startup time has passed, a
comparison is done and appropriate peripheral events and interrupts are also generated. The comparator and
GCLK_AC_DIG are then disabled again automatically, unless configured to wake up the system from sleep.
29.6.3 Selecting Comparator Inputs
Each comparator has one positive and one negative input. The positive input is fed from an external input pin (AINx). The
negative input can be fed either from an external input pin (AINx) or from one of the several internal reference voltage
sources common to all comparators. The user selects the input source as follows:
z
The positive input is selected by the Positive Input MUX Select bit group in the Comparator Control register
(COMPCTRLx.MUXPOS)
z
The negative input is selected by the Negative Input MUX Select bit group in the Comparator Control
register (COMPCTRLx.MUXNEG)
In the case of using an external I/O pin, the selected pin must be configured for analog usage in the PORT Controller by
disabling the digital input and output. The switching of the analog input multiplexors is controlled to minimize crosstalk
between the channels. The input selection must be changed only while the individual comparator is disabled.
29.6.4 Window Operation
Each comparator pair can be configured to work together in window mode. In this mode, a voltage range is defined, and
the comparators give information about whether an input signal is within this range or not. Window mode is enabled by
the Window Enable x bit in the Window Control register (WINCTRL.WENx). Both comparators in a pair must have the
same measurement mode setting in their respective Comparator Control Registers (COMPCTRLx.SINGLE).
To physically configure the pair of comparators for window mode, the same I/O pin should be chosen for each
comparator’s positive input to create the shared input signal. The negative inputs define the range for the window. In
Figure 29-4, COMP0 defines the upper limit and COMP1 defines the lower limit of the window, as shown but the window
will also work in the opposite configuration with COMP0 lower and COMP1 higher. The current state of the window
function is available in the Window x State bit group of the Status register (STATUS.WSTATEx).
Window mode can be configured to generate interrupts when the input voltage changes to below the window, when the
input voltage changes to above the window, when the input voltage changes into the window or when the input voltage
changes outside the window. The interrupt selections are set by the Window Interrupt Selection bit group in the Window
Control register (WINCTRL.WINTSELx[1:0]). Events are generated using the inside/outside state of the window,
regardless of whether the interrupt is enabled or not. Note that the individual comparator outputs, interrupts and events
continue to function normally during window mode.
When the comparators are configured for window mode and single-shot mode, measurements are performed
simultaneously on both comparators. Writing a one to either Start Comparison bit in the Control B register
(CTRLB.STARTx) starts a measurement. Likewise either peripheral event can start a measurement.
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Figure 29-4. Comparators in Window Mode
+
STATE0
COMP0
UPPER LIMIT OF WINDOW
-
WSTATE[1:0]
INTERRUPT
SENSITIVITY
CONTROL
&
WINDOW
FUNCTION
INPUT SIGNAL
INTERRUPTS
EVENTS
+
STATE1
COMP1
LOWER LIMIT OF WINDOW
-
29.6.5 Voltage Doubler
The AC contains a voltage doubler that can reduce the resistance of the analog multiplexors when the supply voltage is
below 2.5V. The voltage doubler is normally switched on/off automatically based on the supply level. When enabling the
comparators, additional start-up time is required for the voltage doubler to settle. If the supply voltage is guaranteed to be
above 2.5V, the voltage doubler can be disabled by writing the Low-Power Mux bit in the Control A register
(CTRLA.LPMUX) to one. Disabling the voltage doubler saves power and reduces the start-up time.
29.6.6 VDDANA Scaler
The VDDANA scaler generates a reference voltage that is a fraction of the device’s supply voltage, with 64 levels. One
independent voltage channel is dedicated for each comparator. The scaler is enabled when a comparator’s Negative
Input Mux bit group in its Comparator Control register (COMPCTRLx.MUXNEG) is set to five and the comparator is
enabled. The voltage of each channel is selected by the Value bit group in the Scaler x registers
(SCALERx.VALUE[5:0]).
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Figure 29-5. VDDANA Scaler
COMPCTRLx.MUXNEG
== 5
SCALERx.
VALUE
6
to
COMPx
29.6.7 Input Hysteresis
Application software can selectively enable/disable hysteresis for the comparison. Applying hysteresis will help prevent
constant toggling of the output, which can be caused by noise when the input signals are close to each other. Hysteresis
is enabled for each comparator individually by the Hysteresis Mode bit in the Comparator x Control register
(COMPCTRLx.HYST). Hysteresis is available only in continuous mode (COMPCTRLx.SINGLE=0).
29.6.8 Propagation Delay vs. Power Consumption
It is possible to trade off comparison speed for power efficiency to get the shortest possible propagation delay or the
lowest power consumption. The speed setting is configured for each comparator individually by the Speed bit group in
the Comparator x Control register (COMPCTRLx.SPEED). The Speed bits select the amount of bias current provided to
the comparator, and as such will also affect the start-up time.
29.6.9 Filtering
The output of the comparators can be digitally filtered to reduce noise using a simple digital filter. The filtering is
determined by the Filter Length bits in the Comparator Control x register (COMPCTRLx.FLEN), and is independent for
each comparator. Filtering is selectable from none, 3-bit majority (N=3) or 5-bit majority (N=5) functions. Any change in
the comparator output is considered valid only if N/2+1 out of the last N samples agree. The filter sampling rate is the
CLK_AC frequency scaled by the prescaler setting in the Control A register (CTRLA.PRESCALER).
Note that filtering creates an additional delay of N-1 sampling cycles from when a comparison is started until the
comparator output is validated. For continuous mode, the first valid output will occur when the required number of filter
samples is taken. Subsequent outputs will be generated every cycle based on the current sample plus the previous N-1
samples, as shown in Figure 29-6. For single-shot mode, the comparison completes after the Nth filter sample, as shown
in Figure 29-7.
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Figure 29-6. Continuous Mode Filtering
Sampling Clock
Sampled
Comparator Output
3-bit Majority
Filter Output
5-bit Majority
Filter Output
Figure 29-7. Single-Shot Filtering
Sampling Clock
Start
t SUT
3-bit Sampled
Comparator Output
3-bit Majority
Filter Output
5-bit Sampled
Comparator Output
5-bit Majority
Filter Output
During sleep modes, filtering is supported only for single-shot measurements. Filtering must be disabled if continuous
measurements will be done during sleep modes, or the resulting interrupt/event may be generated incorrectly.
29.6.10 Comparator Output
The output of each comparator can be routed to an I/O pin by setting the Output bit group in the Comparator Control x
register (COMPCTRLx.OUT). This allows the comparator to be used by external circuitry. Either the raw, nonsynchronized output of the comparator or the CLK_AC-synchronized version, including filtering, can be used as the I/O
signal source. The output appears on the corresponding CMP[x] pin.
29.6.11 Offset Compensation
The Swap bit in the Comparator Control registers (COMPCTRLx.SWAP) controls switching of the input signals to a
comparator's positive and negative terminals. When the comparator terminals are swapped, the output signal from the
comparator is also inverted, as shown in Figure 29-8. This allows the user to measure or compensate for the comparator
input offset voltage. As part of the input selection, COMPCTRLx.SWAP can be changed only while the comparator is
disabled.
Figure 29-8. Input Swapping for Offset Compensation
+
MUXPOS
COMPx
-
CMPx
HYSTERESIS
ENABLE
SWAP
MUXNEG
COMPCTRLx
SWAP
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29.7
Additional Features
29.7.1 Interrupts
The peripheral has the following interrupt sources:
z
Comparator (COMPx): this is an asynchronous interrupt and can be used to wake-up the device from any sleep
mode.
z
Window (WINx): this is an asynchronous interrupt and can be used to wake-up the device from any sleep mode.
Comparator interrupts are generated based on the conditions selected by the Interrupt Selection bit group in the
Comparator Control registers (COMPCTRLx.INTSEL). Window interrupts are generated based on the conditions
selected by the Window Interrupt Selection bit group in the Window Control register (WINCTRL.WINTSEL[1:0]).
Each interrupt source has an interrupt flag associated with it. The interrupt flag in the Interrupt Flag Status and Clear
register (INTFLAG) is set when the interrupt condition occurs. Each interrupt can be individually enabled by writing a one
to the corresponding bit in the Interrupt Enable Set register (INTENSET), and disabled by writing a one to the
corresponding bit in the Interrupt Enable Clear register (INTENCLR). An interrupt request is generated when the interrupt
flag is set and the corresponding interrupt is enabled. The interrupt request remains active until the interrupt flag is
cleared, the interrupt is disabled or the peripheral is reset. An interrupt flag is cleared by writing a one to the
corresponding bit in the INTFLAG register.
Each peripheral can have one interrupt request line per interrupt source or one common interrupt request line for all the
interrupt sources. If the peripheral has one common interrupt request line for all the interrupt sources, the user must read
the INTFLAG register to determine which interrupt condition is present.
For details on clearing interrupt flags, refer to the INTFLAG register description.
Note that interrupts must be globally enabled for interrupt requests to be generated. Refer to “Nested Vector Interrupt
Controller” on page 30 for details.
29.7.2 Events
The peripheral can generate the following output events:
z
Comparator: COMPEO0, COMPEO1(EVCTRL)
z
Window: WINEO0(EVCTRL)
Output events must be enabled to be generated. Writing a one to an Event Output bit in the Event Control register
(EVCTRL.COMPEOx) enables the corresponding output event. Writing a zero to this bit disables the corresponding
output event. The events must be correctly routed in the Event System. Refer to “EVSYS – Event System” on page 313
for details.
The peripheral can take the following actions on an input event:
z
Single-shot measurement
z
Single-shot measurement in window mode
Input events must be enabled for the corresponding action to be taken on any input event. Writing a one to an Event
Input bit in the Event Control register (EVCTRL.COMPEIx) enables the corresponding action on input event. Writing a
zero to a bit disables the corresponding action on input event. Note that if several events are connected to the peripheral,
the enabled action will be taken on any of the incoming events. The events must be correctly routed in the Event System.
Refer to “EVSYS – Event System” on page 313 for details.
When EVCTRL.COMPEIx is one, the event will start a comparison on COMPx after the start-up time delay. In normal
mode, each comparator responds to its corresponding input event independently. For a pair of comparators in window
mode, either comparator event will trigger a comparison on both comparators simultaneously.
29.7.3 Sleep Mode Operation
The Run in Standby bit in the Control A register (CTRLA.RUNSTDBY) controls the behavior of the AC during standby
sleep mode. When the bit is zero, the comparator pair is disabled during sleep, but maintains its current configuration.
When the bit is one, the comparator pair continues to operate during sleep. Note that when RUNSTDBY is zero, the
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analog blocks are powered off for the lowest power consumption. This necessitates a start-up time delay when the
system returns from sleep.
When RUNSTDBY is one, any enabled AC interrupt source can wake up the CPU. While the CPU is sleeping, singleshot comparisons are only triggerable by events. The AC can also be used during sleep modes where the clock used by
the AC is disabled, provided that the AC is still powered (not in shutdown). In this case, the behavior is slightly different
and depends on the measurement mode, as listed in Table 29-1.
Table 29-1. Sleep Mode Operation
COMPCTRLx.MODE
RUNSTDBY=0
RUNSTDBY=1
0 (Continuous)
COMPx disabled
GCLK_AC_DIG stopped, COMPx enabled
1 (Single-shot)
COMPx disabled
GCLK_AC_DIG stopped, COMPx enabled only
when triggered by an input event
29.7.3.1 Continuous Measurement during Sleep
When a comparator is enabled in continuous measurement mode and GCLK_AC_DIG is disabled during sleep, the
comparator will remain continuously enabled and will function asynchronously. The current state of the comparator is
asynchronously monitored for changes. If an edge matching the interrupt condition is found, GCLK_AC_DIG is started to
register the interrupt condition and generate events. If the interrupt is enabled in the Interrupt Enable registers
(INTENCLR/SET), the AC can wake up the device; otherwise GCLK_AC_DIG is disabled until the next edge detection.
Filtering is not possible with this configuration.
Figure 29-9. Continuous Mode SleepWalking
GCLK_AC
Comparator State
Comparator
Output or Event
29.7.3.2 Single-Shot Measurement during Sleep
For low-power operation, event-triggered measurements can be performed during sleep modes. When the event occurs,
the Power Manager will start GCLK_AC_DIG. The comparator is enabled, and after the start-up time has passed, a
comparison is done, with filtering if desired, and the appropriate peripheral events and interrupts are also generated, as
shown in Figure 29-10 The comparator and GCLK_AC_DIG are then disabled again automatically, unless configured to
wake the system from sleep. Filtering is allowed with this configuration.
Figure 29-10.Single-Shot SleepWalking
GCLK_AC
tSTARTUP
t STARTUP
Input Event
Comparator
Output or Event
29.7.4 Synchronization
Due to the asynchronicity between CLK_MODULE_APB and GCLK_MODULE, some registers must be synchronized
when accessed. A register can require:
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z
Synchronization when written
z
Synchronization when read
z
Synchronization when written and read
z
No synchronization
When executing an operation that requires synchronization, the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set immediately, and cleared when synchronization is complete.
If an operation that requires synchronization is executed while STATUS.SYNCBUSY is one, the bus will be stalled. All
operations will complete successfully, but the CPU will be stalled and interrupts will be pending as long as the bus is
stalled.
The following bits need synchronization when written:
z
Software Reset bit in Control A register (CTRLA.SWRST)
z
Enable bit in Control A register (CTRLA.ENABLE)
z
Enable bit in Comparator Control register (COMPCTRLn.ENABLE)
The following register need synchronization when written:
z
Window Control register (WINCTRL)
Refer to the Synchronization chapter for further details.
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29.8
Register Summary
Offset
Name
Bit Pos.
0x00
CTRLA
7:0
0x01
CTRLB
7:0
0x02
LPMUX
RUNSTDBY
WINEO0
7:0
ENABLE
SWRST
START1
START0
COMPEO1
COMPEO0
COMPEI1
COMPEI0
EVCTRL
0x03
15:8
0x04
INTENCLR
7:0
WIN0
COMP1
COMP0
0x05
INTENSET
7:0
WIN0
COMP1
COMP0
0x06
INTFLAG
7:0
WIN0
COMP1
COMP0
0x07
Reserved
0x08
STATUSA
7:0
STATE1
STATE0
0x09
STATUSB
7:0
READY1
READY0
0x0A
STATUSC
7:0
STATE1
STATE0
0x0B
Reserved
0x0C
WINCTRL
0x0D
Reserved
0x0E
Reserved
0x0F
Reserved
0x10
WSTATE0[1:0]
SYNCBUSY
WSTATE0[1:0]
7:0
WINTSEL0[1:0]
7:0
0x11
15:8
INTSEL[1:0]
SPEED[1:0]
MUXPOS[1:0]
SWAP
WEN0
SINGLE
ENABLE
MUXNEG[2:0]
COMPCTRL0
0x12
23:16
0x13
31:24
0x14
7:0
0x15
15:8
HYST
OUT[1:0]
FLEN[2:0]
INTSEL[1:0]
SWAP
SPEED[1:0]
MUXPOS[1:0]
SINGLE
ENABLE
MUXNEG[2:0]
COMPCTRL1
0x16
23:16
0x17
31:24
HYST
OUT[1:0]
FLEN[2:0]
0x18
Reserved
...
Reserved
0x1F
Reserved
0x20
SCALER0
7:0
VALUE[5:0]
0x21
SCALER1
7:0
VALUE[5:0]
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29.9
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-Protected property in each individual register description. Refer to “Register Access Protection” on page 523
for details.
Some registers require synchronization when read and/or written. Synchronization is denoted by the Write-Synchronized
or the Read-Synchronized property in each individual register description. Refer to “Synchronization” on page 531 for
details.
Some registers are enable-protected, meaning they can be written only when the AC is disabled. Enable-protection is
denoted by the Enable-Protected property in each individual register description.
29.9.1 Control A
Name:
CTRLA
Offset:
0x00
Reset:
0x00
Property:
Write-Protected, Write-Synchronized
Bit
7
6
5
4
3
LPMUX
Access
Reset
z
2
1
0
RUNSTDBY
ENABLE
SWRST
R/W
R
R
R
R
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bit 7 – LPMUX: Low-Power Mux
0: The analog input muxes have low resistance, but consume more power at lower voltages (e.g., are driven by the
voltage doubler).
1: The analog input muxes have high resistance, but consume less power at lower voltages (e.g., the voltage doubler is disabled).
This bit are not synchronized
z
Bits 6:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – RUNSTDBY: Run in Standby
This bit controls the behavior of the comparators during standby sleep mode.
0: The comparator pair is disabled during sleep.
1: The comparator pair continues to operate during sleep.
This bit is not synchronized
z
Bit 1 – ENABLE: Enable
0: The AC is disabled.
1: The AC is enabled. Each comparator must also be enabled individually by the Enable bit in the Comparator
Control register (COMPCTRLn.ENABLE).
Due to synchronization, there is delay from updating the register until the peripheral is enabled/disabled. The value
written to CTRL.ENABLE will read back immediately after being written. STATUS.SYNCBUSY is set. STATUS.SYNCBUSY is cleared when the peripheral is enabled/disabled.
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z
Bit 0 – SWRST: Software Reset
0: There is no reset operation ongoing.
1: The reset operation is ongoing.
Writing a zero to this bit has no effect.
Writing a one to this bit resets all registers in the AC to their initial state, and the AC will be disabled.
Writing a one to CTRL.SWRST will always take precedence, meaning that all other writes in the same write-operation will be discarded.
Due to synchronization, there is a delay from writing CTRLA.SWRST until the reset is complete. CTRLA.SWRST
and STATUS.SYNCBUSY will both be cleared when the reset is complete.
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29.9.2 Control B
Name:
CTRLB
Offset:
0x01
Reset:
0x00
Property:
–
Bit
7
6
5
4
3
2
1
0
START1
START0
Access
R
R
R
R
R
R
W
W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 1:0 – STARTx: Comparator x Start Comparison
Writing a zero to this field has no effect.
Writing a one to STARTx starts a single-shot comparison on COMPx if both the Single-Shot and Enable bits in the
Comparator x Control Register are one (COMPCTRLx.SINGLE and COMPCTRLx.ENABLE). If comparator x is
not implemented, or if it is not enabled in single-shot mode, writing a one has no effect.
This bit always reads as zero.
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29.9.3 Event Control
Name:
EVCTRL
Offset:
0x02
Reset:
0x0000
Property:
Write-Protected, Enable-Protected
Bit
15
14
13
12
11
10
9
8
COMPEI1
COMPEI0
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
COMPEO1
COMPEO0
WINEO0
Access
R
R
R
R/W
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 15:10 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 9:8 – COMPEIx: Comparator x Event Input
Note that several actions can be enabled for incoming events. If several events are connected to the peripheral,
the enabled action will be taken for any of the incoming events. There is no way to tell which of the incoming
events caused the action.
These bits indicate whether a comparison will start or not on any incoming event.
0: Comparison will not start on any incoming event.
1: Comparison will start on any incoming event.
z
Bits 7:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 4 – WINEO0: Window 0 Event Output Enable
This bit indicates whether the window 0 function can generate a peripheral event or not.
0: Window 0 event is disabled.
1: Window 0 event is enabled.
z
Bits 3:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 1:0 – COMPEOx: Comparator x Event Output Enable
These bits indicate whether the comparator x output can generate a peripheral event or not.
0: COMPx event generation is disabled.
1: COMPx event generation is enabled.
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29.9.4 Interrupt Enable Clear
This register allows the user to disable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Set register (INTENSET).
Name:
INTENCLR
Offset:
0x04
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
WIN0
1
0
COMP1
COMP0
Access
R
R
R
R/W
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 4 – WIN0: Window 0 Interrupt Enable
Reading this bit returns the state of the Window 0 interrupt enable.
0: The Window 0 interrupt is disabled.
1: The Window 0 interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit disables the Window 0 interrupt.
z
Bits 3:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 1:0 – COMPx: Comparator x Interrupt Enable
Reading this bit returns the state of the Comparator x interrupt enable.
0: The Comparator x interrupt is disabled.
1: The Comparator x interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit disables the Comparator x interrupt.
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29.9.5 Interrupt Enable Set
This register allows the user to enable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Clear register (INTENCLR).
Name:
INTENSET
Offset:
0x05
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
WIN0
1
0
COMP1
COMP0
Access
R
R
R
R/W
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 4 – WIN0: Window 0 Interrupt Enable
Reading this bit returns the state of the Window 0 interrupt enable.
0: The Window 0 interrupt is disabled.
1: The Window 0 interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit enables the Window 0 interrupt.
z
Bits 3:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 1:0 – COMPx: Comparator x Interrupt Enable
Reading this bit returns the state of the Comparator x interrupt enable.
0: The Comparator x interrupt is disabled.
1: The Comparator x interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Ready interrupt bit and enable the Ready interrupt.
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29.9.6 Interrupt Flag Status and Clear
Name:
INTFLAG
Offset:
0x06
Reset:
0x00
Property:
–
Bit
7
6
5
4
3
2
WIN0
1
0
COMP1
COMP0
Access
R
R
R
R/W
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 4 – WIN0: Window 0
This flag is set according to the Window 0 Interrupt Selection bit group in the WINCTRL register (WINCTRL.WINTSEL0) and will generate an interrupt if INTENCLR/SET.WIN0 is also one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Window 0 interrupt flag.
z
Bits 3:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 1:0 – COMPx: Comparator x
Reading this bit returns the status of the Comparator x interrupt flag. If comparator x is not implemented, COMPx
always reads as zero.
This flag is set according to the Interrupt Selection bit group in the Comparator x Control register (COMPCTRLx.INTSEL) and will generate an interrupt if INTENCLR/SET.COMPx is also one.
Writing a zero to this bit has no effect.
Writing a one to this bit clears the Comparator x interrupt flag.
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29.9.7 Status A
Name:
STATUSA
Offset:
0x08
Reset:
0x00
Property:
–
Bit
7
6
5
4
3
2
WSTATE0[1:0]
1
0
STATE1
STATE0
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bits 7:6 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 5:4 – WSTATE0[1:0]: Window 0 Current State
These bits show the current state of the signal if the window 0 mode is enabled, according to Table 29-2. If the window 0 function is not implemented, WSTATE0 always reads as zero.
Table 29-2. Window Mode Current State
WSTATE0[1:0]
Name
Description
0x0
ABOVE
Signal is above window
0x1
INSIDE
Signal is inside window
0x2
BELOW
Signal is below window
0x3
–
Reserved
z
Bits 3:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 1:0 – STATEx: Comparator x Current State
This bit shows the current state of the output signal from COMPx. STATEx is valid only when STATUSB.READYx
is one.
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29.9.8 Status B
Name:
STATUSB
Offset:
0x09
Reset:
0x00
Property:
–
Bit
7
6
5
4
3
2
SYNCBUSY
1
0
READY1
READY0
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bit 7 – SYNCBUSY: Synchronization Busy
This bit is cleared when the synchronization of registers between the clock domains is complete.
This bit is set when the synchronization of registers between clock domains is started.
z
Bits 6:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 1:0 – READYx: Comparator x Ready
This bit is cleared when the comparator x output is not ready.
This bit is set when the comparator x output is ready.
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29.9.9 Status C
STATUSC is a copy of STATUSA (see STATUSA register), with the additional feature of automatically starting singleshot comparisons. A read of STATUSC will start a comparison on all comparators currently configured for single-shot
operation. The read will stall the bus until all enabled comparators are ready. If a comparator is already busy with a
comparison, the read will stall until the current comparison is compete, and a new comparison will not be started.
Name:
STATUSC
Offset:
0x0A
Reset:
0x00
Property:
–
Bit
7
6
5
4
3
2
WSTATE0[1:0]
1
0
STATE1
STATE0
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bits 7:6 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 5:4 – WSTATE0[1:0]: Window 0 Current State
These bits show the current state of the signal if the window 0 mode is enabled. If the window 0 function is not
implemented, WSTATE0 always reads as zero.
Table 29-3. Window Mode Current State
WSTATE0[1:0]
Name
Description
0x0
ABOVE
Signal is above window
0x1
INSIDE
Signal is inside window
0x2
BELOW
Signal is below window
0x3
–
Reserved
z
Bits 3:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 1:0 – STATEx: Comparator x Current State
This bit shows the current state of the output signal from COMPx. If comparator x is not implemented, STATEx
always reads as zero. STATEx is only valid when STATUSB.READYx is one.
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29.9.10 Window Control
Name:
WINCTRL
Offset:
0x0C
Reset:
0x00
Property:
Write-Synchronized, Write-Protected
Bit
7
6
5
4
3
2
1
WINTSEL0[1:0]
0
WEN0
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 2:1 – WINTSEL[1:0]: Window 0 Interrupt Selection
These bits configure the interrupt mode for the comparator window 0 mode.
Table 29-4. Window 0 Interrupt Selection
WINTSEL[1:0]
Name
Description
0x0
ABOVE
Interrupt on signal above window
0x1
INSIDE
Interrupt on signal inside window
0x2
BELOW
Interrupt on signal below window
0x3
OUTSIDE
Interrupt on signal outside window
z
Bit 0 – WEN0: Window 0 Mode Enable
0: Window mode is disabled for comparators 0 and 1.
1: Window mode is enabled for comparators 0 and 1.
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29.9.11 Scaler n
Name:
SCALERn
Offset:
0x20+n*0x1 [n=0..1]
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
VALUE[5:0]
Access
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:6 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 5:0 – VALUE[5:0]: Scaler Value
These bits define the scaling factor for channel n of the VDDANA voltage scaler. The output voltage, VSCALE, is:
V DDANA ⋅ ( VALUE + 1 )
V SCALE = -----------------------------------------------------------64
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29.9.12 Comparator Control n
The configuration of comparator n is protected while comparator n is enabled (COMPCTRLn.ENABLE = 1). Changes to
the other bits in COMPCTRLn can only occur when COMPCTRLn.ENABLE is zero.
Name:
COMPCTRLn
Offset:
0x10+n*0x4 [n=0..1]
Reset:
0x00000000
Property:
Write-Protected, Write-Synchronized
Bit
31
30
29
28
27
26
25
24
FLEN[2:0]
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
23
22
21
20
19
18
17
16
Bit
HYST
OUT[1:0]
Access
R
R
R
R
R/W
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
8
SWAP
Access
MUXPOS[1:0]
MUXNEG[2:0]
R/W
R
R/W
R/W
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
SINGLE
ENABLE
INTSEL[1:0]
SPEED[1:0]
Access
R
R/W
R/W
R
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 31:27 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 26:24 – FLEN[2:0]: Filter Length
These bits configure the filtering for comparator n. COMPCTRLn.FLEN can only be written while COMPCTRLn.ENABLE is zero.
These bits are not synchronized.
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Table 29-5. Filter Length
FLEN[2:0]
Name
Description
0x0
OFF
No filtering
0x1
MAJ3
3-bit majority function (2 of 3)
0x2
MAJ5
5-bit majority function (3 of 5)
0x3-0x7
N/A
Reserved
z
Bits 23:20 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 19 – HYST: Hysteresis Enable
This bit indicates the hysteresis mode of comparator n. Hysteresis is available only for continuous mode (COMPCTRLn.SINGLE=0). COMPCTRLn.HYST can be written only while COMPCTRLn.ENABLE is zero.
0: Hysteresis is disabled.
1: Hysteresis is enabled.
These bits are not synchronized.
z
Bit 18 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 17:16 – OUT[1:0]: Output
These bits configure the output selection for comparator n. COMPCTRLn.OUT can be written only while COMPCTRLn.ENABLE is zero.
These bits are not synchronized.
Table 29-6. Output Selection
OUT[1:0]
Name
Description
0x0
OFF
The output of COMPn is not routed to the COMPn I/O
port
0x1
ASYNC
The asynchronous output of COMPn is routed to the
COMPn I/O port
0x2
SYNC
The synchronous output (including filtering) of COMPn
is routed to the COMPn I/O port
0x3
N/A
Reserved
z
Bit 15 – SWAP: Swap Inputs and Invert
This bit swaps the positive and negative inputs to COMPn and inverts the output. This function can be used for offset cancellation. COMPCTRLn.SWAP can be written only while COMPCTRLn.ENABLE is zero.
0: The output of MUXPOS connects to the positive input, and the output of MUXNEG connects to the negative
input.
1: The output of MUXNEG connects to the positive input, and the output of MUXPOS connects to the negative
input.
These bits are not synchronized.
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z
Bit 14 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 13:12 – MUXPOS[1:0]: Positive Input Mux Selection
These bits select which input will be connected to the positive input of comparator n. COMPCTRLn.MUXPOS can
be written only while COMPCTRLn.ENABLE is zero.
These bits are not synchronized.
Table 29-7. Positive Input Mux Selection
MUXPOS[1:0]
Name
Description
0x0
PIN0
I/O pin 0
0x1
PIN1
I/O pin 1
0x2
PIN2
I/O pin 2
0x3
PIN3
I/O pin 3
z
Bit 11 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 10:8 – MUXNEG[2:0]: Negative Input Mux Selection
These bits select which input will be connected to the negative input of comparator n. COMPCTRLn.MUXNEG can
only be written while COMPCTRLn.ENABLE is zero.
These bits are not synchronized.
Table 29-8. Negative Input Mux Selection
MUXNEG[2:0]
Name
Description
0x0
PIN0
I/O pin 0
0x1
PIN1
I/O pin 1
0x2
PIN2
I/O pin 2
0x3
PIN3
I/O pin 3
0x4
GND
Ground
0x5
VSCALE
VDDANA scaler
0x6
BANDGAP
Internal bandgap voltage
0x7
DAC
DAC output
z
Bit 7 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 6:5 – INTSEL[1:0]: Interrupt Selection
These bits select the condition for comparator n to generate an interrupt or event. COMPCTRLn.INTSEL can be
written only while COMPCTRLn.ENABLE is zero.
These bits are not synchronized.
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Table 29-9. Interrupt Selection
INTSEL[1:0]
Name
Description
0x0
TOGGLE
Interrupt on comparator output toggle
0x1
RISING
Interrupt on comparator output rising
0x2
FALLING
Interrupt on comparator output falling
0x3
EOC
Interrupt on end of comparison (single-shot mode only)
z
Bit 4 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 3:2 – SPEED[1:0]: Speed Selection
This bit indicates the speed/propagation delay mode of comparator n. COMPCTRLn.SPEED can be written only
while COMPCTRLn.ENABLE is zero.
These bits are not synchronized.
Table 29-10. Speed Selection
SPEED[1:0]
Name
Description
0x0
LOW
Low speed
0x1
HIGH
High speed
0x2-0x3
Reserved
z
Bit 1 – SINGLE: Single-Shot Mode
This bit determines the operation of comparator n. COMPCTRLn.SINGLE can be written only while COMPCTRLn.ENABLE is zero.
0: Comparator n operates in continuous measurement mode.
1: Comparator n operates in single-shot mode.
These bits are not synchronized.
z
Bit 0 – ENABLE: Enable
Writing a zero to this bit disables comparator n.
Writing a one to this bit enables comparator n.
After writing to this bit, the value read back will not change until the action initiated by the writing is complete. Due
to synchronization, there is a latency of at least two GCLK_AC_DIG clock cycles from updating the register until
the comparator is enabled/disabled. The bit will continue to read the previous state while the change is in progress.
Writing a one to COMPCTRLn.ENABLE will prevent further changes to the other bits in COMPCTRLn. These bits
remain protected until COMPCTRLn.ENABLE is written to zero and the write is synchronized.
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30.
30.1
DAC – Digital-to-Analog Converter
Overview
The Digital-to-Analog Converter (DAC) converts a digital value to a voltage. The DAC has one channel with 10-bit
resolution, and it is capable of converting up to 350,000 samples per second (350ksps).
30.2
Features
z DAC with 10-bit resolution
z Up to 350ksps conversion rate
z Multiple trigger sources
z High-drive capabilities
z Output can be used as input to the Analog Comparator (AC)
30.3
Block Diagram
Figure 30-1. DAC Block Diagram
EVCTRL
EVENT
CONTROL
EMPTY
START
DATABUF
DATA
Output
driver
DAC10
CTRLA
VOUT
ADC
CTRLB
AC
AVCC
STATUS
INT1V
VREFA
30.4
Signal Description
Signal Name
Type
Description
VOUT
Analog output
DAC output
VREFA
Analog input
External reference
Refer to “I/O Multiplexing and Considerations” on page 16 for the pin mapping of this peripheral. One signal can be
mapped on several pins.
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30.5
Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
30.5.1 I/O Lines
Using the DAC’s I/O lines requires the I/O pins to be configured using the port configuration (PORT).
Refer to “PORT” on page 287 for details.
30.5.2 Power Management
The DAC will continue to operate in any sleep mode where the selected source clock is running. The DAC interrupts can
be used to wake up the device from sleep modes. The events can trigger other operations in the system without exiting
sleep modes. Refer to “PM – Power Manager” on page 107 for details on the different sleep modes.
30.5.3 Clocks
The DAC bus clock (CLK_DAC_APB) can be enabled and disabled in the Power Manager, and the default state of
CLK_DAC_APB can be found in the Peripheral Clock Masking section in “PM – Power Manager” on page 107.
A generic clock (GCLK_DAC) is required to clock the DAC. This clock must be configured and enabled in the Generic
Clock Controller before using the DAC. Refer to “GCLK – Generic Clock Controller” on page 85 for details.
This generic clock is asynchronous to the bus clock (CLK_DAC). Due to this asynchronicity, writes to certain registers will
require synchronization between the clock domains. Refer to “Synchronization” on page 554 for further details.
30.5.4 DMA
Not applicable.
30.5.5 Interrupts
The interrupt request line is connected to the Interrupt Controller. Using the DAC interrupts requires the Interrupt
Controller to be configured first. Refer to “Nested Vector Interrupt Controller” on page 30 for details.
30.5.6 Events
The events are connected to the Event System. Refer to “EVSYS – Event System” on page 313 for details on how to
configure the Event System.
30.5.7 Debug Operation
When the CPU is halted in debug mode the DAC continues normal operation. If the DAC is configured in a way that
requires it to be periodically serviced by the CPU through interrupts or similar, improper operation or data loss may result
during debugging.
30.5.8 Register Access Protection
All registers with write-access are optionally write-protected by the Peripheral Access Controller (PAC), except the
following register:
z
Interrupt Flag Status and Clear register (INTFLAG)
Write-protection is denoted by the Write-Protection property in the register description.
When the CPU is halted in debug mode, all write-protection is automatically disabled.
Write-protection does not apply for accesses through an external debugger. Refer to “PAC – Peripheral Access
Controller” on page 34 for details.
30.5.9 Analog Connections
Not applicable.
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30.6
Functional Description
30.6.1 Principle of Operation
The Digital-to-Analog Converter (DAC) converts the digital value written to the Data register (DATA) into an analog
voltage on the DAC output. By default, a conversion is started when new data is written to DATA, and the corresponding
voltage is available on the DAC output after the conversion time. It is also possible to enable events from the Event
System to trigger the conversion.
30.6.2 Basic Operation
30.6.2.1 Initialization
Before enabling the DAC, it must be configured by selecting the voltage reference using the Reference Selection bits in
the Control B register (CTRLB.REFSEL).
30.6.2.2 Enabling, Disabling and Resetting
The DAC is enabled by writing a one to the Enable bit in the Control A register (CTRLA.ENABLE). The DAC is disabled
by writing a zero to CTRLA.ENABLE.
The DAC is reset by writing a one to the Software Reset bit in the Control A register (CTRLA.SWRST). All registers in the
DAC will be reset to their initial state, and the DAC will be disabled. Refer to the CTRLA register for details.
30.6.2.3 Enabling the Output Buffer
To enable the DAC output on the VOUT pin, the output driver must be enabled by writing a one to the External Output
Enable bit in the Control B register (CTRLB.EOEN).
The DAC output buffer provides a high-drive-strength output, and is capable of driving both resistive and capacitive
loads. To minimize power consumption, the output buffer should be enabled only when external output is needed.
30.6.3 Additional Features
30.6.3.1 Conversion Range
The conversion range is between GND and the selected DAC voltage reference. The default voltage reference is the
internal 1V (INT1V) reference voltage. The other voltage reference options are the 3.3V analog supply voltage (AVCC =
VDDANA) and the external voltage reference (VREFA). The voltage reference is selected by writing to the Reference
Selection bits in the Control B register (CTRLB.REFSEL). The output voltage from the DAC can be calculated using the
following formula:
DATA
V DAC = ----------------- ⋅ VREF
0x3FF
30.6.3.2 DAC as an Internal Reference
The DAC output can be internally enabled as input to the analog comparator. This is enabled by writing a one to the
Internal Output Enable bit in the Control B register (CTRLB.IOEN). It is possible to have the internal and external output
enabled simultaneously.
The DAC output can also be enabled as input to the Analog-to-Digital Converter. In this case, the output buffer must be
enabled.
30.6.3.3
Data Buffer
The Data Buffer register (DATABUF) and the Data register (DATA) are linked together to form a two-stage FIFO. The
DAC uses the Start Conversion event to load data from DATABUF into DATA and start a new conversion. The Start
Conversion event is enabled by writing a one to the Start Event Input bit in the Event Control register
(EVCTRL.STARTEI). If a Start Conversion event occurs when DATABUF is empty, an Underrun interrupt request is
generated if the Underrun interrupt is enabled.
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The DAC can generate a Data Buffer Empty event when DATABUF becomes empty and new data can be loaded to the
buffer. The Data Buffer Empty event is enabled by writing a one to the Empty Event Output bit in the Event Control
register (EVCTRL.EMPTYEO). A Data Buffer Empty interrupt request is generated if the Data Buffer Empty interrupt is
enabled.
30.6.3.4 Voltage Pump
When the DAC is used at operating voltages lower than 2.5V, the voltage pump must be enabled. This enabling is done
automatically, depending on operating voltage.
The voltage pump can be disabled by writing a one to the Voltage Pump Disable bit in the Control B register
(CTRLB.VPD). This can be used to reduce power consumption when the operating voltage is above 2.5V.
The voltage pump uses the asynchronous GCLK_DAC clock, and requires that the clock frequency be at least four times
higher than the sampling period.
30.6.3.5 Sampling Period
As there is no automatic indication that a conversion is done, the sampling period must be greater than or equal to the
specified conversion time.
30.6.4 DMA Operation
Not applicable.
30.6.5 Interrupts
The DAC has the following interrupt sources:
z
Data Buffer Empty (EMPTY): this asynchronous interrupt can be used to wake-up the device from any sleep mode.
z
Underrun (UNDERRUN): this asynchronous interrupt can be used to wake-up the device from any sleep mode.
z
Synchronization Ready (SYNCRDY): this asynchronous interrupt can be used to wake-up the device from any
sleep mode.
Each interrupt source has an interrupt flag associated with it. The interrupt flag in the Interrupt Flag Status and Clear
register (INTFLAG) is set when the interrupt condition occurs. Each interrupt can be individually enabled by writing a one
to the corresponding bit in the Interrupt Enable Set register (INTENSET), and disabled by writing a one to the
corresponding bit in the Interrupt Enable Clear register (INTENCLR). An interrupt request is generated when the interrupt
flag is set and the corresponding interrupt is enabled. The interrupt request remains active until the interrupt flag is
cleared, the interrupt is disabled or the DAC is reset. See the register description for details on how to clear interrupt
flags.
The DAC has one common interrupt request line for all the interrupt sources. The user must read the INTFLAG register
to determine which interrupt condition is present.
Note that interrupts must be globally enabled for interrupt requests to be generated. Refer to “Nested Vector Interrupt
Controller” on page 30 for details.
30.6.6 Events
The DAC can generate the following output events:
z
Data Buffer Empty (EMPTY)
Writing a one to an Event Output bit in the Event Control register (EVCTRL.xxEO) enables the corresponding output
event. Writing a zero to this bit disables the corresponding output event. Refer to “EVSYS – Event System” on page 313
for details on configuring the event system.
The DAC can take the following actions on an input event:
z
Start Conversion (START)
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Writing a one to an Event Input bit in the Event Control register (EVCTRL.xxEI) enables the corresponding action on an
input event. Writing a zero to this bit disables the corresponding action on input event. Note that if several events are
connected to the DAC, the enabled action will be taken on any of the incoming events. Refer to “EVSYS – Event System”
on page 313 for details on configuring the event system.
30.6.7 Sleep Mode Operation
The generic clock for the DAC is running in idle sleep mode. If the Run In Standby bit in the Control A register
(CTRLA.RUNSTDBY) is one, the DAC output buffer will keep its value in standby sleep mode. If CTRLA.RUNSTDBY is
zero, the DAC output buffer will be disabled in standby sleep mode.
30.6.8 Synchronization
Due to the asynchronicity between CLK_DAC_APB and GCLK_DAC, some registers must be synchronized when
accessed. A register can require:
z
Synchronization when written
z
Synchronization when read
z
Synchronization when written and read
z
No synchronization
When executing an operation that requires synchronization, the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set immediately, and cleared when synchronization is complete. The Synchronization
Ready interrupt can be used to signal when synchronization is complete.
If an operation that requires synchronization is executed while STATUS.SYNCBUSY is one, the bus will be stalled. All
operations will complete successfully, but the CPU will be stalled and interrupts will be pending as long as the bus is
stalled.
The following bits need synchronization when written:
z
Software Reset bit in the Control A register (CTRLA.SWRST)
z
Enable bit in the Control A register (CTRLA.ENABLE)
z
All bits in the Data register (DATA)
z
All bits in the Data Buffer register (DATABUF)
Synchronization is denoted by the Write-Synchronized property in the register description.
The following bits need synchronization when read:
z
All bits in the Data register (DATA)
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30.7
Register Summary
Offset
Name
Bit Pos.
0x00
CTRLA
7:0
0x01
CTRLB
7:0
0x02
EVCTRL
7:0
0x03
Reserved
0x04
INTENCLR
7:0
0x05
INTENSET
0x06
0x07
RUNSTDBY
ENABLE
SWRST
LEFTADJ
IOEN
EOEN
EMPTYEO
STARTEI
SYNCRDY
EMPTY
UNDERRUN
7:0
SYNCRDY
EMPTY
UNDERRUN
INTFLAG
7:0
SYNCRDY
EMPTY
UNDERRUN
STATUS
7:0
0x08
REFSEL[1:0]
VPD
SYNCBUSY
7:0
DATA[7:0]
15:8
DATA[15:8]
7:0
DATABUF[7:0]
15:8
DATABUF[15:8]
DATA
0x09
0x0A
Reserved
0x0B
Reserved
0x0C
DATABUF
0x0D
0x0E
Reserved
0x0F
Reserved
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30.8
Register Description
Registers can be 8, 16 or 32 bits wide. Atomic 8-, 16- and 32-bit accesses are supported. In addition, the 8-bit quarters
and 16-bit halves of a 32-bit register and the 8-bit halves of a 16-bit register can be accessed directly.
Some registers are optionally write-protected by the Peripheral Access Controller (PAC). Write-protection is denoted by
the Write-Protected property in each individual register description. Refer to “Register Access Protection” on page 551
for details.
Some registers require synchronization when read and/or written. Synchronization is denoted by the Synchronized
property in each individual register description. Refer to “Synchronization” on page 554 for details.
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30.8.1 Control A
Name:
CTRLA
Offset:
0x0
Reset:
0x00
Property:
Write-Protected, Write-Synchronized
Bit
7
6
5
4
3
2
1
0
RUNSTDBY
ENABLE
SWRST
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – RUNSTDBY: Run in Standby
0: The DAC output buffer is disabled in standby sleep mode.
1: The DAC output buffer can be enabled in standby sleep mode.
This bit is not synchronized.
z
Bit 1 – ENABLE: Enable
0: The peripheral is disabled or being disabled.
1: The peripheral is enabled or being enabled.
Due to synchronization, there is delay from writing CTRLA.ENABLE until the peripheral is enabled/disabled. The
value written to CTRL.ENABLE will read back immediately and the Synchronization Busy bit in the Status register
(STATUS.SYNCBUSY) will be set. STATUS.SYNCBUSY is cleared when the operation is complete.
z
Bit 0 – SWRST: Software Reset
0: There is no reset operation ongoing.
1: The reset operation is ongoing.
Writing a zero to this bit has no effect.
Writing a one to this bit resets the all registers in the DAC to their initial state, and the DAC will be disabled.
Writing a one to CTRLA.SWRST will always take precedence, meaning that all other writes in the same write operation will be discarded.
Due to synchronization, there is a delay from writing CTRLA.SWRST until the reset is complete. CTRLA.SWRST
and STATUS.SYNCBUSY will both be cleared when the reset is complete.
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30.8.2 Control B
Name:
CTRLB
Offset:
0x1
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
REFSEL[1:0]
Access
Reset
z
4
3
2
1
0
-
VPD
LEFTADJ
IOEN
EOEN
R/W
R/W
R
R
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 7:6 – REFSEL[1:0]: Reference Selection
These bits select the reference voltage for the DAC according to Table 30-1.
Table 30-1. Reference Selection
REFSEL[1:0]
Reference Selection
Description
0x0
INT1V
Internal 1.0V reference
0x1
AVCC
AVCC
0x2
VREFA
External reference
0x3
Reserved
z
Bits 5:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 3 – VPD: Voltage Pump Disable
This bit controls the behavior of the voltage pump.
0: Voltage pump is turned on/off automatically.
1: Voltage pump is disabled.
z
Bit 2 – LEFTADJ: Left-Adjusted Data
This bit controls how the 10-bit conversion data is adjusted in the Data and Data Buffer registers.
0: DATA and DATABUF registers are right-adjusted.
1: DATA and DATABUF registers are left-adjusted.
z
Bit 1 – IOEN: Internal Output Enable
0: Internal DAC output not enabled.
1: Internal DAC output enabled to be used by the AC.
z
Bit 0 – EOEN: External Output Enable
0: The DAC output is turned off.
1: The high-drive output buffer drives the DAC output to the VOUT pin.
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30.8.3 Event Control
Name:
EVCTRL
Offset:
0x2
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
EMPTYEO
STARTEI
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 1 – EMPTYEO: Data Buffer Empty Event Output
This bit indicates whether or not the Data Buffer Empty event is enabled and will be generated when the Data Buffer register is empty.
0: Data Buffer Empty event is disabled and will not be generated.
1: Data Buffer Empty event is enabled and will be generated.
z
Bit 0 – STARTEI: Start Conversion Event Input
This bit indicates whether or not the Start Conversion event is enabled and data are loaded from the Data Buffer
register to the Data register upon event reception.
0: A new conversion will not be triggered on an incoming event.
1: A new conversion will be triggered on an incoming event.
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30.8.4 Interrupt Enable Clear
This register allows the user to disable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Set register (INTENSET).
Name:
INTENCLR
Offset:
0x4
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
SYNCRDY
EMPTY
UNDERRUN
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – SYNCRDY: Synchronization Ready Interrupt Enable
0: The Synchronization Ready interrupt is disabled.
1: The Synchronization Ready interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Synchronization Ready Interrupt Enable bit, which disables the Synchronization Ready interrupt.
z
Bit 1 – EMPTY: Data Buffer Empty Interrupt Enable
0: The Data Buffer Empty interrupt is disabled.
1: The Data Buffer Empty interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Data Buffer Empty Interrupt Enable bit, which disables the Data Buffer Empty
interrupt.
z
Bit 0 – UNDERRUN: Underrun Interrupt Enable
0: The Underrun interrupt is disabled.
1: The Underrun interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Underrun Interrupt Enable bit, which disables the Underrun interrupt.
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30.8.5 Interrupt Enable Set
This register allows the user to enable an interrupt without doing a read-modify-write operation. Changes in this register
will also be reflected in the Interrupt Enable Clear register (INTENCLR).
Name:
INTENSET
Offset:
0x5
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
SYNCRDY
EMPTY
UNDERRUN
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – SYNCRDY: Synchronization Ready Interrupt Enable
0: The Synchronization Ready interrupt is disabled.
1: The Synchronization Ready interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Synchronization Ready Interrupt Enable bit, which enables the Synchronization
Ready interrupt.
z
Bit 1 – EMPTY: Data Buffer Empty Interrupt Enable
0: The Data Buffer Empty interrupt is disabled.
1: The Data Buffer Empty interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Data Buffer Empty Interrupt Enable bit, which enables the Data Buffer Empty
interrupt.
z
Bit 0 – UNDERRUN: Underrun Interrupt Enable
0: The Underrun interrupt is disabled.
1: The Underrun interrupt is enabled.
Writing a zero to this bit has no effect.
Writing a one to this bit will set the Underrun Interrupt Enable bit, which enables the Underrun interrupt.
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30.8.6 Interrupt Flag Status and Clear
Name:
INTFLAG
Offset:
0x6
Reset:
0x00
Property:
Write-Protected
Bit
7
6
5
4
3
2
1
0
SYNCRDY
EMPTY
UNDERRUN
Access
R
R
R
R
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
z
Bits 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bit 2 – SYNCRDY: Synchronization Ready
This flag is cleared by writing a one to the flag.
This flag is set on a 1-to-0 transition of the Synchronization Busy bit in the Status register (STATUS.SYNCBUSY),
except when the transition is caused by an enable or a software reset, and will generate an interrupt request if
INTENCLR/SET.READY is one.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Synchronization Ready interrupt flag.
z
Bit 1 – EMPTY: Data Buffer Empty
This flag is cleared by writing a one to the flag or by writing new data to DATABUF.
This flag is set when data is transferred from DATABUF to DATA, and the DAC is ready to receive new data in
DATABUF, and will generate an interrupt request if INTENCLR/SET.EMPTY is one.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Data Buffer Empty interrupt flag.
z
Bit 0 – UNDERRUN: Underrun
This flag is cleared by writing a one to the flag.
This flag is set when a start conversion event occurs when DATABUF is empty, and will generate an interrupt
request if INTENCLR/SET.UNDERRUN is one.
Writing a zero to this bit has no effect.
Writing a one to this bit will clear the Underrun interrupt flag.
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30.8.7 Status
Name:
STATUS
Offset:
0x7
Reset:
0x00
Property:
Read-Synchronized
Bit
7
6
5
4
3
2
1
0
SYNCBUSY
Access
R
R
R
R
R
R
R
R
Reset
0
0
0
0
0
0
0
0
z
Bit 7 – SYNCBUSY: Synchronization Busy Status
This bit is cleared when the synchronization of registers between the clock domains is complete.
This bit is set when the synchronization of registers between clock domains is started.
z
Bits 6:0 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
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30.8.8 Data
Name:
DATA
Offset:
0x8
Reset:
0x0000
Property:
Write-Synchronized, Read-Synchronized, Write-Protected
Bit
15
14
13
12
11
10
9
8
DATA[15:8]
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DATA[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 15:0 – DATA: Data value to be converted
DATA register contains the 10-bit value that is converted to a voltage by the DAC. The adjustment of these 10 bits
within the 16-bit register is controlled by CTRLB.LEFTADJ:
- DATA[9:0] when CTRLB.LEFTADJ is zero.
- DATA[15:6] when CTRLB.LEFTADJ is one.
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30.8.9 Data Buffer
Name:
DATABUF
Offset:
0xC
Reset:
0x0000
Property:
Write-Synchronized, Write-Protected
Bit
15
14
13
12
11
10
9
8
DATABUF[15:8]
Access
R
R
R
R
R
R
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
DATABUF[7:0]
Access
Reset
z
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 15:0 – DATABUF: Data Buffer
DATABUF contains the value to be transferred into DATA register.
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31.
PTC - Peripheral Touch Controller
31.1
Overview
The purpose of PTC is to acquire signals to detect touch on capacitive sensors. The external capacitive touch sensor is
typically formed on a PCB, and the sensor electrodes are connected to the analog front end of the PTC through the I/O
pins in the device. The PTC supports both self- and mutual-capacitance sensors.
In mutual-capacitance mode, sensing is done using capacitive touch matrices in various X-Y configurations, including
indium tin oxide (ITO) sensor grids. The PTC requires one pin per X-line and one pin per Y-line.
In self-capacitance mode, the PTC requires only one pin (Y-line) for each touch sensor.
31.2
Features
z Low-power, high-sensitivity, environmentally robust capacitive touch buttons, sliders, wheels and proximity sensing
z
Down to 8µA with 200ms scan rate
z Supports mutual capacitance and self-capacitance sensing
z
6/10/16 buttons in self-capacitance mode, for 32-/48-/64- pins respectively
60/120/256 buttons in mutual-capacitance mode, for 32-/48-/64- pins respectively
z Mix-and-match mutual-and self-capacitance sensors
z
z One pin per electrode – no external components
z Load compensating charge sensing
z
Parasitic capacitance compensation and adjustable gain for superior sensitivity
z Zero drift over the temperature and VDD range
z
Auto calibration and re-calibration of sensors
z Single-shot and free-running charge measurement
z Hardware noise filtering and noise signal de-synchronization for high conducted immunity
z Selectable channel change delay
z
Allows choosing the settling time on a new channel, as required
z Acquisition-start triggered by command or interrupt event
z Low CPU utilization through interrupt on acquisition-complete
z
5% CPU utilization scanning 10 channels at 50ms scan rate
z Supported by the Atmel® QTouch® Composer development tool, which comprises QTouch Library project builder and
QTouch analyzer
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31.3
Block Diagram
Figure 31-1. PTC Block Diagram Mutual-capacitance
Input
Control
Compensation
Circuit
Y0
Y1
Y15
RS
Acquisition Module
100K
IRQ
- Gain control
- ADC
- Filtering
Result
10
CX0Y0
X0
X Line Driver
X1
CX15Y0
X15
Figure 31-2. PTC Block Diagram Self-capacitance
Input
Control
Compensation
Circuit
Y0
Y1
RS
CY0
Y15
100K
Acquisition Module
IRQ
- Gain control
- ADC
- Filtering
Result
10
CY15
X Line Driver
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31.4
Signal Description
Name
Type
Description
X[n:0]
Digital
X-line (Output)
Y[m:0]
Analog
Y-line (Input/Output)
Note:
1.
The number of X and Y lines are device dependent. Refer to “Configuration Summary” on page 3 for details.
Refer to “I/O Multiplexing and Considerations” on page 16 for details on the pin mapping for this peripheral. One signal
can be mapped on several pins.
31.5
Product Dependencies
In order to use this Peripheral, configure the other components of the system as described in the following sections.
31.5.1 I/O Lines
The I/O lines used for analog X-lines and Y-lines must be connected to external capacitive touch sensor electrodes.
External components are not required for normal operation. However, to improve the EMC performance, a series resistor
of 1 KΩ can be used on X-lines and Y-lines.
Mutual-capacitance Sensor Arrangement
A mutual-capacitance sensor is formed between two I/O lines - an X electrode for transmitting and Y electrode for
receiving. The mutual capacitance between the X and Y electrode is measured by the Peripheral Touch Controller.
Figure 31-3. Mutual Capacitance Sensor Arrangement
Sensor Capacitance Cx,y
MCU
X0
X1
Xn
Cx0,y0
Cx0,y1
Cx0,ym
Cx1,y0
Cx1,y1
Cx1,ym
Cxn,y0
Cxn,y1
Cxn,ym
PTC
PTC
Module
Module
Y0
Y1
Ym
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Self-capacitance Sensor Arrangement
The self-capacitance sensor is connected to a single pin on the Peripheral Touch Controller through the Y electrode for
receiving the signal. The sense electrode capacitance is measured by the Peripheral Touch Controller.
Figure 31-4. Self-capacitance Sensor Arrangement
MCU
Sensor Capacitance Cy
Y0
Cy0
Y1
PTC
Module
Ym
Cy1
Cym
For more information about designing the touch sensor, refer to Buttons, Sliders and Wheels Touch Sensor Design
Guide on http://www.atmel.com.
31.5.2 Clocks
The PTC is clocked by the GCLK_PTC clock. The PTC operates from an asynchronous clock source and the operation is
independent of the main system clock and its derivative clocks, such as the peripheral bus clock (CLK_APB). A number
of clock sources can be selected as the source for the asynchronous GCLK_PTC. The clock source is selected by
configuring the Generic Clock Selection ID in the Generic Clock Control register. For more information about selecting
the clock sources, refer to “GCLK – Generic Clock Controller” on page 85.
The selected clock must be enabled in the Power Manager, before it can be used by the PTC. By default these clocks are
disabled. The frequency range of GCLK_PTC is 400kHz to 4MHz.
For more details, refer to “PM – Power Manager” on page 107.
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31.6
Functional Description
In order to access the PTC, the user must use the QTouch Composer tool to configure and link the QTouch Library
firmware with the application code. QTouch Library can be used to implement buttons, sliders, wheels and proximity
sensor in a variety of combinations on a single interface.
For more information about QTouch library, refer to the Atmel QTouch Library Peripheral Touch Controller User Guide.
Figure 31-5. QTouch Library Usage
Custom Code
Compiler
Link
Application
Atmel Qtouch
Library
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32.
Electrical Characteristics
32.1
Disclaimer
All typical values are measured at T = 25°C unless otherwise specified. All minimum and maximum values are valid
across operating temperature and voltage unless otherwise specified.
32.2
Absolute Maximum Ratings
Stresses beyond those listed in Table 32-1 may cause permanent damage to the device. This is a stress rating only and
functional operation of the device at these or other conditions beyond those indicated in the operational sections of this
specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device
reliability.
Table 32-1. Absolute maximum ratings
Symbol
VDD
Parameter
Min.
Max.
Units
0
3.8
V
Power supply voltage
(1)
IVDD
Current into a VDD pin
-
92
mA
IGND
Current out of a GND pin
-
130(1)
mA
VPIN
Pin voltage with respect to GND and VDD
GND-0.3V
VDD+0.3V
V
-60
150
°C
Tstorage
Note:
1.
Storage temp
Maximum source current is 46mA and maximum sink current is 65mA per cluster. A cluster is a group of GPIOs as shown in Table 32-2. Also note
that each VDD/GND pair is connected to 2 clusters so current consumption through the pair will be a sum of the clusters source/sink currents.
Table 32-2. GPIO Clusters
PACKAGE
64pins
CLUSTER
SUPPLIES PINS
CONNECTED TO THE
CLUSTER
GPIO
1
PB31
PB30
PA31
PA30
VDDIN pin56/GND pin54
2
PA28
PA27
PB23
PB22
VDDIN pin56/GND pin54 and
VDDIO pin 48/GND pin47
3
PA25
PA24
PA23
PA22
PA21
PA20
PB17
PB16
PA19
PA18
4
PA15
PA14
PA13
PA12
PB15
PB14
PB13
PB12
PB11
PB10
5
PA11
PA10
PA09
PA08
6
PA07
PA06
PA05
PA04
PB09
PB08
PB07
PB06
7
PB05
PB04
PA03
PA02
PA01
PA00
PB03
PB02
PA17
PA16
VDDIO pin 48/GND pin47
and VDDIO pin34/GND pin33
VDDIO pin 34/GND pin33
and VDDIO pin21/GND pin22
VDDIO pin21/GND pin22
VDDANA pin 8/GNDANA
pin7
PB01
PB00
VDDANA pin 8/GNDANA
pin7
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Table 32-2. GPIO Clusters (Continued)
PACKAGE
CLUSTER
48pins
32pins
32.3
SUPPLIES PINS
CONNECTED TO THE
CLUSTER
GPIO
1
PA31
PA30
VDDIN pin44/GND pin42
2
PA28
PA27
PB23
PB22
3
PA25
PA24
PA23
PA22
4
PA11
PA10
PA09
PA08
5
PA07
PA06
PA05
6
PA03
PA02
PA01
1
PA31
PA30
2
PA28
PA27
PA25
PA24
PA23
PA22
PA19
PA18
3
PA07
PA06
PA05
PA04
PA03
PA02
PA01
PA00
VDDIN pin44/GND pin42 and
VDDIO pin36/GND pin35
PA19
PA18
PA17
PA16
PA15
PA14
PA13
PA12
PB11
PB10
VDDIO pin36/GND pin35 and
VDDIO pin17/GND pin18
PA21
PA20
PA04
PB09
PB08
VDDANA pin6/GNDANA pin5
PA00
PB03
PB02
VDDANA pin6/GNDANA pin5
VDDIO pin17/GND pin18
VDDIN pin30/GND pin 28
PA17
PA16
PA15
PA14
PA11
PA10
PA09
PA08
VDDIN pin30/GND pin 28 and
VDDANA pin9/GND pin10
VDDANA pin9/GND pin10
General Operating Ratings
The device must operate within the ratings listed in Table 32-3 in order for all other electrical characteristics and typical
characteristics of the device to be valid.
Table 32-3. General operating conditions
Symbol
Parameter
Min.
Typ.
Max.
Units
VDD
Power supply voltage
1.62(1)
3.3
3.63
V
VDDANA
Analog supply voltage
1.62(1)
3.3
3.63
V
-40
25
85
°C
-
-
100
°C
Notes:
TA
Temperature range
TJ
Junction temperature
1.
With BOD33 disabled. If the BOD33 is enabled, check Table 32-17
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32.4
Supply Characteristics
The following characteristics are applicable to the operating temperature range: TA = -40°C to 85°C, unless otherwise
specified and are valid for a junction temperature up to TJ = 100°C. Refer to “Power Supply and Start-Up Considerations”
on page 21.
Table 32-4. Supply Characteristics
Voltage
Symbol
Conditions
Min.
Max.
Units
VDDIO
VDDIN
VDDANA
Full Voltage Range
1.62
3.63
V
Table 32-5. Supply Rise Rates
Rise Rate
32.5
Symbol
Parameter
VDDIO
VDDIN
VDDANA
DC supply peripheral I/Os, internal regulator and analog supply
voltage
Max.
Units
0.1
V/µs
Maximum Clock Frequencies
Table 32-6. Maximum GCLK Generator Output Frequencies
Symbol
Description
Max.
Units
fGCLKGEN0/fGCLK_MAIN
fGCLKGEN1
fGCLKGEN2
fGCLKGEN3
fGCLKGEN4
fGCLKGEN5
fGCLKGEN6
fGCLKGEN7
GCLK Generator Output Frequency
48
MHz
Max.
Units
Table 32-7. Maximum Peripheral Clock Frequencies
Symbol
Description
fCPU
CPU clock frequency
48
MHz
fAHB
AHB clock frequency
48
MHz
fAPBA
APBA clock frequency
48
MHz
fAPBB
APBB clock frequency
48
MHz
fAPBC
APBC clock frequency
48
MHz
35.1
kHz
48
MHz
fGCLK_DFLL48M_REF
fGCLK_WDT
DFLL48M Reference clock frequency
WDT input clock frequency
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Table 32-7. Maximum Peripheral Clock Frequencies (Continued)
Symbol
Description
Max.
Units
fGCLK_RTC
RTC input clock frequency
48
MHz
fGCLK_EIC
EIC input clock frequency
48
MHz
fGCLK_EVSYS_CHANNEL_0
EVSYS channel 0 input clock frequency
48
MHz
fGCLK_EVSYS_CHANNEL_1
EVSYS channel 1 input clock frequency
48
MHz
fGCLK_EVSYS_CHANNEL_2
EVSYS channel 2 input clock frequency
48
MHz
fGCLK_EVSYS_CHANNEL_3
EVSYS channel 3 input clock frequency
48
MHz
fGCLK_EVSYS_CHANNEL_4
EVSYS channel 4 input clock frequency
48
MHz
fGCLK_EVSYS_CHANNEL_5
EVSYS channel 5 input clock frequency
48
MHz
fGCLK_EVSYS_CHANNEL_6
EVSYS channel 6 input clock frequency
48
MHz
fGCLK_EVSYS_CHANNEL_7
EVSYS channel 7 input clock frequency
48
MHz
fGCLK_SERCOMx_SLOW
Common SERCOM slow input clock
frequency
48
MHz
fGCLK_SERCOM0_CORE
SERCOM0 input clock frequency
48
MHz
fGCLK_SERCOM1_CORE
SERCOM1 input clock frequency
48
MHz
fGCLK_SERCOM2_CORE
SERCOM2 input clock frequency
48
MHz
fGCLK_SERCOM3_CORE
SERCOM3 input clock frequency
48
MHz
fGCLK_SERCOM4_CORE
SERCOM4 input clock frequency
48
MHz
fGCLK_SERCOM5_CORE
SERCOM5 input clock frequency
48
MHz
fGCLK_TC0, GCLK_TC1
TC0,TC1 input clock frequency
48
MHz
fGCLK_TC2, GCLK_TC3
TC2,TC3 input clock frequency
48
MHz
fGCLK_TC4, GCLK_TC5
TC4,TC5 input clock frequency
48
MHz
fGCLK_TC6, GCLK_TC7
TC6,TC7 input clock frequency
48
MHz
ADC input clock frequency
48
MHz
fGCLK_AC_DIG
AC digital input clock frequency
48
MHz
fGCLK_AC_ANA
AC analog input clock frequency
64
kHz
fGCLK_DAC
DAC input clock frequency
350
kHz
fGCLK_PTC
PTC input clock frequency
48
MHz
fGCLK_ADC
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32.6
Power Consumption
The values in Table 32-8 are measured values of power consumption under the following conditions, except where
noted:
z
Operating conditions
z
VVDDIN = 3.3V
z
Wake up time from sleep mode is measured from the edge of the wakeup signal to the execution of the first
instruction fetched in flash.
z
Oscillators
z
z
z
XOSC (crystal oscillator) stopped
z
XOSC32K (32kHz crystal oscillator) running with external 32kHz crystal
z
DFLL48M using XOSC32K as reference and running at 48MHz
Clocks
z
DFLL48M used as main clock source, except otherwise specified.
z
CPU, AHB clocks undivided
z
APBA clock divided by 4
z
APBB and APBC bridges off
The following AHB module clocks are running: NVMCTRL, APBA bridge
z
z
All other AHB clocks stopped
The following peripheral clocks running: PM, SYSCTRL, RTC
z
All other peripheral clocks stopped
z
I/Os are inactive with internal pull-up
z
CPU is running on flash with 1 wait states
z
NVMCTRL cache enabled
z
BOD33 disabled
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Table 32-8. Current Consumption
Mode
Conditions
TA
Min.
Typ.
Max.
25°C
2.13
2.33
2.52
85°C
2.24
2.44
2.63
CPU running a While(1) algorithm VDDIN=1.8V,
CPU is running on Flash with 3 wait states
25°C
2.13
2.34
2.53
85°C
2.26
2.45
2.64
CPU running a While(1) algorithm, CPU is
running on Flash with 3 wait states with
GCLKIN as reference
25°C
-
42*freq
+118
-
85°C
-
42*freq
+208
-
25°C
3.63
4.03
4.37
85°C
3.74
4.12
4.44
25°C
3.64
4.03
4.37
wait states
85°C
3.76
4.13
4.44
CPU running a Fibonacci algorithm, CPU is
running on Flash with 3 wait states with
GCLKIN as reference
25°C
-
80*freq
+118
-
85°C
-
80*freq
+208
-
25°C
5.22
5.72
6.16
85°C
5.36
5.89
6.37
25°C
4.58
4.95
5.27
wait states
85°C
4.74
5.10
5.42
CPU running a CoreMark algorithm, CPU is
running on Flash with 3 wait states with
GCLKIN as reference
25°C
-
94*freq
+118
-
85°C
-
96*freq
+210
-
25°C
1.24
1.35
1.45
85°C
1.31
1.45
1.57
25°C
0.87
0.95
1.03
85°C
0.91
1.03
1.13
25°C
0.72
0.78
0.85
85°C
0.76
0.86
0.96
25°C
-
3.80
11.95
85°C
-
39.91
100
25°C
-
2.46
11.13
85°C
-
38.23
100
Units
CPU running a While(1) algorithm
mA
µA
(with freq
in MHz)
CPU running a Fibonacci algorithm
CPU running a Fibonacci algorithm
VDDIN=1.8V, CPU is running on flash with 3
ACTIVE
mA
µA
(with freq
in MHz)
CPU running a CoreMark algorithm
CPU running a CoreMark algorithm
VDDIN=1.8V, CPU is running on flash with 3
IDLE0
IDLE1
IDLE2
mA
µA
(with freq
in MHz)
I
mA
I
I
XOSC32K running
RTC running at 1kHz
STANDBY
µA
XOSC32K and RTC stopped
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Table 32-9. Wake-up Time
Mode
Conditions
IDLE0
OSC8M used as main clock source, cache disabled
IDLE1
I
TA
Min.
Typ.
Max.
25°C
3.3
4.0
4.5
85°C
3.4
4.0
4.5
25°C
10.5
12.1
13.7
85°C
12.1
13.6
15.0
25°C
11.7
13.0
14.3
85°C
13.0
14.5
15.9
25°C
17.5
19.6
21.4
85°C
18.0
19.7
21.4
Units
OSC8M used as main clock source, cache disabled
µs
IDLE2
STANDBY
I
I
OSC8M used as main clock source, cache disabled
OSC8M used as main clock source, cache disabled
Figure 32-1. Measurement Schematic
SAM D20
VDDIN
VDDANA
VDDIO
Amp 0
VDDCORE
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32.7
Peripheral Power Consumption
Default conditions, except where noted:
z
Operating conditions
z
z
z
z
Oscillators
z
XOSC (crystal oscillator) stopped
z
XOSC32K (32kHz crystal oscillator) running with external 32kHz crystal
z
OSC8M at 8MHz
Clocks
z
OSC8M used as main clock source
z
CPU, AHB and APBn clocks undivided
The following AHB module clocks are running: NVMCTRL, HPB2 bridge, HPB1 bridge, HPB0 bridge
z
z
VVDDIN = 3.3V
All other AHB clocks stopped
The following peripheral clocks running: PM, SYSCTRL
z
All other peripheral clocks stopped
z
I/Os are inactive with internal pull-up
z
CPU in IDLE0 mode
z
Cache enabled
z
BOD33 disabled
In this default conditions, the power consumption Idefault is measured.
Operating mode for each peripheral in turn:
z
Configure and enable the peripheral GCLK (When relevant, see conditions)
z
Unmask the peripheral clock
z
Enable the peripheral (when relevant)
z
Set CPU in IDLE0 mode
z
Measurement Iperiph
z
Wake-up CPU via EIC (async: level detection, filtering disabled)
z
Disable the peripheral (when relevant)
z
Mask the peripheral clock
z
Disable the peripheral GCLK (when relevant, see conditions)
Each peripheral power consumption provided in table x-9 is the value (Iperiph - Idefault), using the same measurement
method as for global power consumption measurement.
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Table 32-10. Typical Peripheral Power Consumption
Peripheral
Typ.
RTC
fGCLK_RTC = 32kHz, 32bit counter mode
5.6
WDT
fGCLK_WDT=32kHz, normal mode with EW
4.2
Both fGCLK=8MHz, Enable both COMP
25.8
fGCLK=8MHz, Enable + COUNTER in 8bit mode
41.5
SERCOMx.I2CM(2)
fGCLK=8MHz, Enable
50.3
SERCOMx.I2CS(2)
fGCLK=8MHz, Enable
23.6
SERCOMx.SPI(2)
fGCLK=8MHz, Enable
47.9
SERCOMx.USART(2)
fGCLK=8MHz, Enable
47.6
AC
TCx(1)
Notes:
Conditions
1.
2.
Units
µA
All TCs share the same power consumption values.
All SERCOMs share the same power consumption values.
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32.8
I/O Pin Characteristics
32.8.1 Normal I/O Pins
Table 32-11. RevD and later normal I/O Pins Characteristics
Symbol
Parameter
RPULL
Pull-up - Pull-down resistance
VIL
Input low-level voltage
VIH
Input high-level voltage
VOL
Output low-level voltage
VOH
Output high-level voltage
IOL
Conditions
Min.
Typ.
Max.
Units
20
40
60
kΩ
VDD=1.62V-2.7V
-
-
0.25*VDD
VDD=2.7V-3.63V
-
-
0.3*VDD
VDD=1.62V-2.7V
0.7*VDD
-
-
VDD=2.7V-3.63V
0.55*VDD
-
-
VDD>1.6V, IOL maxI
-
0.1*VDD
0.2*VDD
VDD>1.6V, IOH maxI
0.8*VDD
0.9*VDD
-
VDD=1.62V-3V,
PORT.PINCFG.DRVSTR=0
-
-
1
VDD=3V-3.63V,
PORT.PINCFG.DRVSTR=0
-
-
2.5
VDD=1.62V-3V,
PORT.PINCFG.DRVSTR=1
-
-
3
VDD=3V-3.63V,
PORT.PINCFG.DRVSTR=1
-
-
10
I
V
Output low-level current
mA
IOH
VDD=1.62V-3V,
PORT.PINCFG.DRVSTR=0
-
-
0.7
VDD=3V-3.63V,
PORT.PINCFG.DRVSTR=0
-
-
2
VDD=1.62V-3V,
PORT.PINCFG.DRVSTR=1
-
-
2
VDD=3V-3.63V,
PORT.PINCFG.DRVSTR=1
-
-
7
PORT.PINCFG.DRVSTR=0
load = 5pF, VDD = 3.3V
-
-
15
PORT.PINCFG.DRVSTR=1
load = 20pF, Vdd = 3.3V
-
-
15
Output high-level current
tRISE
Rise time
(1)
nS
(1)
tFALL
Fall time
ILEAK
Note:
Input leakage current
1.
PORT.PINCFG.DRVSTR=0
load = 5pF, VDD = 3.3V
-
-
15
PORT.PINCFG.DRVSTR=1
load = 20pF, Vdd = 3.3V
-
-
15
Pull-up resistors disabled
-1
+/-0.015
1
µA
These values are based on simulation. These values are not covered by test limits in production or characterization.
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Table 32-12. SAMD20 revC/revB Normal I/O Pins Characteristics
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
20
40
60
kΩ
VDD=1.62V-2.7V
-
-
0.25*VDD
VDD=2.7V-3.63V
-
-
0.3*VDD
VDD=1.62V-2.7V
0.7*VDD
-
-
VDD=2.7V-3.63V
0.55*VDD
-
-
RPULL
Pull-up - Pull-down resistance
VIL
Input low-level voltage
VIH
Input high-level voltage
VOL
Output low-level voltage
VDD>1.6V, IOL maxI
-
0.1*VDD
0.2*VDD
VOH
Output high-level voltage
VDD>1.6V, IOH maxI
0.8*VDD
0.9*VDD
-
-
8
Output low-level current
VDD=1.6V-3V
-
IOL
VDD=3V-3.63V
-
-
20
VDD=1.6V-3V
-
-
4.5
VDD=3V-3.63V
-
-
10
load=30pF,Vdd=3.3V,
slope range [10%90%]
-
7
-
-
9.5
-
-1
+/-0.015
1
IOH
Output high-level current
tRISE
Rise time(1)
tFALL
Fall time(1)
ILEAK
Input leakage current
Note:
1.
I
Pull-up resistors
disabled
V
mA
nS
µA
These values are based on simulation. These values are not covered by test limits in production or characterization.
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32.8.2 I2C Pins
Refer to “I/O Multiplexing and Considerations” on page 16 to get the list of I2C pins.
Table 32-13. I2C Pins Characteristics in I2C configuration
Symbol
Parameter
RPULL
Pull-up - Pull-down resistance
VIL
Input low-level voltage
VIH
Input high-level voltage
VHYS
Hysteresis of Schmitt trigger inputs
VOL
Output low-level voltage
IOL
Output low-level current
fSCL
SCL clock frequency
Condition
Min.
Typ.
Max.
Units
20
40
60
kΩ
VDD=1.62V-2.7VI
-
-
0.25*VDD
VDD=2.7V-3.63V
-
-
0.3*VDD
VDD=1.62V-2.7V
0.7*VDD
-
-
VDD=2.7V-3.63VI
0.55*VDD
-
-
0.08*VDD
-
-
VDD> 2.0VI,
IOL=3mA
-
-
0.4
VDD≤2.0V
IOL=2mA
-
-
0.2*VDD
VOL =0.4V
3
-
-
VOL =0.6V
6
-
-
I
-
-
400
I
V
mA
kHz
I2C pins timing characteristics can be found in “SERCOM in I2C Mode Timing” on page 608.
32.8.3 XOSC Pin
XOSC pins behave as normal pins when used as normal I/Os. Refer to Table 32-11.
32.8.4 XOSC32 Pin
XOSC32 pins behave as normal pins when used as normal I/Os. Refer to Table 32-11.
32.8.5 External Reset Pin
Reset pin has the same electrical characteristics as normal I/O pins. Refer to Table 32-11.
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32.9
Analog Characteristics
32.9.1 Voltage Regulator Characteristics
Table 32-14. Voltage Regulator Electrical Characteristics
Symbol
VDDCORE
Note:
Parameter
DC calibrated output voltage
Conditions
Min.
Typ.
Max.
Units
Voltage regulator
normal mode
1.1
1.23
1.30
V
Supplying any external components using VDDCORE pin is not allowed to assure the integrity of the core supply voltage.
Table 32-15. Decoupling requirements
Symbol
Parameter
Conditions
CIN
Input regulator capacitor,
between VDDIN and GND
COUT
Output regulator capacitor,
between VDDCORE and GND
Min.
Typ.
Max.
Units
-
1
-
µF
0.8
1
-
µF
I
32.9.2 Power-On Reset (POR) Characteristics
Table 32-16. POR Characteristics
Symbol
VPOT+
Parameter
Conditions
Voltage threshold on VDD
rising
I
VPOT-
Voltage threshold on VDD
falling
Min.
Typ.
Max.
Units
1.27
1.45
1.58
V
0.72
0.99
1.32
V
VDD falls at 1V/ms or slower
VDD
Figure 32-2. POR Operating Principle
VPOT+
VPOT-
Reset
Time
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32.9.3 Brown-Out Detectors Characteristics
32.9.3.1 BOD33
Figure 32-3. BOD33 Hysteresis OFF
VCC
VBOD
RESET
Figure 32-4. BOD33 Hysteresis ON
VCC
VBOD+
VBOD-
RESET
Table 32-17. BOD33 LEVEL Value
Symbol
BOD33.LEVEL
Conditions
Min.
Typ.
Max.
-
1.715
1.745
-
1.750
1.779
39
-
2.84
2.92
48
-
3.2
3.3
6
1.62
1.64
1.67
1.64
1.675
1.71
2.72
2.77
2.81
3.0
3.07
3.2
6
7
VBOD+
Units
Hysteresis ON
V
VBODor
VBOD
Hysteresis ON
or
Hysteresis OFF
7
39
48
Note:
See chapter Memories table “NVM User Row Mapping” for the BOD33 default value settings.
Table 32-18. BOD33 Characteristics
Symbol
Parameter
Conditions
I
Step size, between
adjacent values in
BOD33.LEVEL
I
VHYST
VBOD+ - VBOD-
Hysteresis ON
tDET
Detection time
Time with VDDANA < VTH
necessary to generate a
reset signal
-
Min.
Typ.
Max.
Units
-
34
-
mV
35
-
170
mV
0.9(1)
-
µs
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Table 32-18. BOD33 Characteristics (Continued)
Symbol
Parameter
IBOD33
Current
consumption
tSTARTUP
Startup time
Note:
1.
Conditions
Min.
Typ.
Max.
Continuous mode
2.9
33
52.2
Sampling mode
-
23
75.5
I
-
2.2(1)
-
Units
µA
µs
These values are based on simulation. These values are not covered by test limits in production or characterization.
32.9.4 Analog-to-Digital (ADC) Characteristics
Table 32-19. Operating Conditions
Symbol
Parameter
RES
Resolution
ADC Clock frequency
fCLK_ADC
Conditions
Sample rate(1)
Min.
Typ.
Max.
Units
I
8
-
12
bits
I
30
-
2100
kHz
Single shot
5
-
300
ksps
Free running
5
-
350(3)
ksps
0.5
-
-
cycles
-
6
-
cycles
Sampling time(1)
Conversion time(1)
1x Gain
VREF
Voltage reference range
1.0
-
VDDANA-0.6
V
VREFINT1V
Internal 1V reference (2)
-
1.0
-
V
VREFINTVCC0
VREFINTVCC0
Voltage Error
VREFINTVCC1
VREFINTVCC1
Voltage Error
Internal ratiometric
reference 0
-40°C to 85°C
-
VDDANA/1.48
-
V
Internal ratiometric
reference 0 error(2)
-40°C to 85°C
-1.0
-
+1.0
%
Internal ratiometric
reference 1
2.0V < VDDANA < 3.63V
-40°C to 85°C
-
VDDANA/2
-
V
Internal ratiometric
reference 1 error (2)
2.0V < VDDANA < 3.63V
-40°C to 85°C
-1.0
-
+1.0
%
-VREF/GAIN
-
+VREF/GAIN
V
0.0
-
+VREF/GAIN
V
-
3.5
-
pF
-
-
3.5
kΩ
-
1.25
1.79
mA
Differential mode
Conversion range(1)
Single-ended mode
CSAMPLE
Sampling capacitance
RSAMPLE
Input channel source
resistance(2)
IDD
DC supply current(1)
Notes:
1.
2.
3.
(2)
fCLK_ADC = 2.1MHzI(3)
These values are based on characterization. These values are not covered by test limits in production.
These values are based on simulation. These values are not covered by test limits in production or characterization.
In this condition and for a sample rate of 350ksps, a conversion takes 6 clock cycles of the ADC clock (conditions: 1X gain, 12-bit resolution, differential mode, free-running).
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Table 32-20. Differential Mode
Symbol
ENOB
Parameter
Units
-
10.5
11.1
bits
Total Unadjusted Error
I
1x Gainn
1.5
4.3
15.0
LSB
INLI
Integral Non Linearity
1x Gainn
1.0
1.3
4.5
LSB
DNL
Differential Non Linearity
1x Gainn
+/-0.3
+/-0.5
+/-0.95
LSB
Ext. Ref 1x
-10.0
2.5
+10.0
mV
VREF=VDDANA/1.48
-15.0
-1.5
+10.0
mV
Bandgap
-20.0
-5.0
+20.0
mV
Ext. Ref. 0.5x
+/-0.1
+/-0.2
+/-0.45
%
Ext. Ref. 2x to 16x
+/-0.05
+/-0.1
+/-0.11
%
Ext. Ref. 1x
-5.0
-1.5
+5.0
mV
VREF=VDDANA/1.48
-5.0
0.5
+5.0
mV
Bandgap
-5.0
3.0
+5.0
mV
62.7
70.0
75.0
dB
54.1
65.0
68.5
dB
54.5
65.5
68.6
dB
-77.0
-64.0
-63.0
dB
0.6
1.0
1.6
mV
Gain Error
Gain Accuracy(5)
Offset Error
SFDR
SINAD
Spurious Free Dynamic Range
Signal-to-Noise and Distortion
SNR
Signal-to-Noise Ratio
THD
Total Harmonic Distortion
Noise RMS
5.
Max.
TUE
I
4.
Typ.
With gain compensation
I
1.
2.
3.
Min.
Effective Number Of Bits
I
Notes:
Conditions
1x Gain
FCLK_ADC = 2.1MHz
FIN = 40kHz
AIN = 95%FSR
T=25°C
Maximum numbers are based on characterization and not tested in production, and valid for 5% to 95% of the input voltage range.
Dynamic parameter numbers are based on characterization and not tested in production.
Respect the input common mode voltage through the following equations (where VCM_IN is the Input channel common mode voltage):
d.
If |VIN| > VREF/4
z
VCM_IN < 0.95*VDDANA + VREF/4 – 0.75V
z
VCM_IN > VREF/4 -0.05*VDDANA -0.1V
e.
If |VIN| < VREF/4
z
VCM_IN < 1.2*VDDANA - 0.75V
z
VCM_IN > 0.2*VDDANA - 0.1V
The ADC channels on pins PA08, PA09, PA10, PA11 are powered from the VDDIO power supply. The ADC performance of these pins will not be the same as
all the other ADC channels on pins powered from the VDDANA power supply.
The gain accuracy represents the gain error expressed in percent. Gain accuracy (%) = (Gain Error in V x 100) / (2*Vref/GAIN)
Table 32-21. Single-Ended Mode
Symbol
ENOB
Parameter
Conditions
Min.
Typ.
Max.
Units
Effective Number of Bits
With gain compensation
-
9.5
9.8
Bits
TUE
Total Unadjusted Error
1x gain
-
10.5
14.0
LSB
INL
Integral Non-Linearity
1x gain
1.0
1.6
3.5
LSB
DNL
Differential Non-Linearity
1x gain
+/-0.5
+/-0.6
+/-0.95
LSB
Gain Error
Ext. Ref. 1x
-5.0
0.7
+5.0
mV
Atmel | SMART SAM D20 [DATASHEET]
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Table 32-21. Single-Ended Mode (Continued)
Symbol
Parameter
Gain Accuracy(4)
Offset Error
SFDR
SINAD
Min.
Typ.
Max.
Units
Ext. Ref. 0.5x
+/-0.2
+/-0.34
+/-0.4
%
Ext. Ref. 2x to 16X
+/-0.01
+/-0.1
+/-0.2
%
-5.0
1.5
+5.0
mV
63.1
65.0
67.0
dB
47.5
59.5
61.0
dB
48.0
60.0
64.0
dB
-65.4
-63.0
-62.1
dB
-
1.0
-
mV
Ext. Ref. 1x
Spurious Free Dynamic Range
Signal-to-Noise and Distortion
SNR
Signal-to-Noise Ratio
THD
Total Harmonic Distortion
Noise RMS
Notes:
Conditions
1x Gain
FCLK_ADC = 2.1MHz
FIN = 40kHz
AIN = 95%FSR
T = 25°C
1.
2.
Maximum numbers are based on characterization and not tested in production, and for 5% to 95% of the input voltage range.
Respect the input common mode voltage through the following equations (where VCM_IN is the Input channel common mode voltage) for all VIN:
z
VCM_IN < 0.7*VDDANA + VREF/4 – 0.75V
z
VCM_IN > VREF/4 – 0.3*VDDANA - 0.1V
3.
The ADC channels on pins PA08, PA09, PA10, PA11 are powered from the VDDIO power supply. The ADC performance of these pins will not be the same as
all the other ADC channels on pins powered from the VDDANA power supply.
The gain accuracy represents the gain error expressed in percent. Gain accuracy (%) = (Gain Error in V x 100) / (Vref/GAIN)
4.
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32.9.4.1 Performance with the Averaging Digital Feature
Averaging is a feature which increases the sample accuracy. ADC automatically computes an average value of multiple
consecutive conversions. The numbers of samples to be averaged is specified by the Number-of-Samples-to-becollected bit group in the Average Control register (AVGCTRL.SAMPLENUM[3:0]) and the averaged output is available
in the Result register (RESULT).
Table 32-22. Averaging feature
Average
Number
Conditions
SNR (dB)
SINAD (dB)
SFDR (dB)
ENOB
(bits)
66.0
65.0
72.8
9.75
67.6
65.8
75.1
10.62
69.7
67.1
75.3
10.85
70.4
67.5
75.5
10.91
1
8
32
In differential mode, 1x gain,
VDDANA=3.0V, VREF=1.0V, 350ksps
T= 25°C
128
32.9.4.2 Performance with the hardware offset and gain correction
Inherent gain and offset errors affect the absolute accuracy of the ADC. The offset error cancellation is handled by the
Offset Correction register (OFFSETCORR) and the gain error cancellation, by the Gain Correction register
(GAINCORR). The offset and gain correction value is subtracted from the converted data before writing the Result
register (RESULT).
Table 32-23. Offset and Gain correction feature
Gain Factor
Conditions
0.5x
1x
2x
8x
In differential mode, 1x gain,
VDDANA=3.0V, VREF=1.0V, 350ksps
T= 25°C
16x
Offset Error
(mV)
Gain Error
(mV)
Total Unadjusted Error
(LSB)
0.25
1.0
2.4
0.20
0.10
1.5
0.15
-0.15
2.7
-0.05
0.05
3.2
0.10
-0.05
6.1
32.9.4.3 Inputs and Sample and Hold Acquisition Times
The analog voltage source must be able to charge the sample and hold (S/H) capacitor in the ADC in order to achieve
maximum accuracy. Seen externally the ADC input consists of a resistor ( R SAMPLE ) and a capacitor ( CSAMPLE ). In addition,
the source resistance ( RSOURCE ) must be taken into account when calculating the required sample and hold time. Figure
32-5 shows the ADC input channel equivalent circuit.
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Figure 32-5. ADC Input
VDDANA/2
Analog Input
AINx
RSOURCE
CSAMPLE
RSAMPLE
VIN
To achieve n bits of accuracy, the
V CSAMPLE ≥ V IN × ( 1 – 2
–( n + 1 )
capacitor must be charged at least to a voltage of
C SAMPLE
)
The minimum sampling time
for a given
t SAMPLEHOLD
R SOURCE can
be found using this formula:
t SAMPLEHOLD ≥ ( R SAMPLE + R SOURCE ) × ( C SAMPLE ) × ( n + 1 ) × ln ( 2 )
for a 12 bits accuracy:
t SAMPLEHOLD ≥ ( R SAMPLE + R SOURCE ) × ( C SAMPLE ) × 9.02
where
1
t SAMPLEHOLD = -------------------2 × f ADC
32.9.5 Digital to Analog Converter (DAC) Characteristics
Table 32-24. Operating Conditions(1)
Symbol
Parameter
VDDANA
Analog supply voltage
AVREF
External reference voltage
Min.
Typ.
Max.
Units
I
1.62
-
3.63
V
I
1.0
-
VDDANA-0.6
V
Internal reference voltage 1
-
1
-
V
Internal reference voltage 2
-
VDDANA
-
V
0.05
-
VDDANA-0.05
V
I
Linear output voltage range
I
Minimum resistive load
I
5
-
-
kΩ
I
Maximum capacitance load
I
-
-
100
pF
Voltage pump disabled
-
160
230
µA
DC supply current(2)
iDD
Notes:
Conditions
1.
2.
I
These values are based on specifications otherwise noted.
These values are based on characterization. These values are not covered by test limits in production.
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Table 32-25. Clock and Timing(1)
Symbol
Parameter
Conditions
Startup time
Note:
1.
Typ.
Max.
Normal mode
-
-
350
For ΔDATA=+/-1
-
-
1000
VDDNA > 2.6V
-
-
2.85
µs
VDDNA < 2.6V
-
-
10
µs
Cload=100pF
Rload > 5kΩ
Conversion rate
I
Min.
Units
ksps
These values are based on simulation. These values are not covered by test limits in production or characterization.
Table 32-26. Accuracy Characteristics(1)
Symbol
RES
Parameter
Conditions
Input resolution
Integral non-linearity
VREF = VDDANA
VREF= INT1V
VREF= Ext 1.0V
DNL
Differential non-linearity
VREF= VDDANA
VREF= INT1V
Note:
Typ.
Max.
Units
-
-
10
Bits
VDD = 1.6V
0.75
1.1
2.5
VDD = 3.6V
0.6
1.2
1.5
VDD = 1.6V
1.4
2.2
2.5
VDD = 3.6V
0.9
1.4
1.5
VDD = 1.6V
0.75
1.3
1.5
VDD = 3.6V
0.8
1.2
1.5
VDD = 1.6V
+/-0.9
+/-1.2
+/-1.5
VDD = 3.6V
+/-0.9
+/-1.1
+/-1.2
VDD = 1.6V
+/-1.1
+/-1.5
+/-1.7
VDD = 3.6V
+/-1.0
+/-1.1
+/-1.2
VDD = 1.6V
+/-1.1
+/-1.4
+/-1.5
VDD = 3.6V
+/-1.0
+/-1.5
+/-1.6
I
VREF= Ext 1.0V
INL
Min.
LSB
LSB
I
Gain error
Ext. VREF
+/-1.5
+/-5
+/-10
mV
I
Offset error
Ext. VREF
+/-2
+/-3
+/-6
mV
Min.
Typ.
Max.
0
-
VDDANA
1.
All values measured using a conversion rate of 350ksps.
32.9.6 Analog Comparator Characteristics
Table 32-27. Electrical and Timing
Symbol
Parameter
Conditions
I
Positive input voltage
range
I
I
Negative input voltage
range
I
Units
V
0
-
VDDANA
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Table 32-27. Electrical and Timing (Continued)
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
Hysteresis = 0, Fast mode
-15
0.0
+15
mV
Hysteresis = 0, Low power mode
-25
0.0
+25
mV
Hysteresis = 1, Fast mode
20
50
80
mV
Hysteresis = 1, Low power mode
15
40
75
mV
Changes for VACM=VDDANA/2
100mV overdrive, Fast mode
-
60
116
ns
Changes for VACM=VDDANA/2
100mV overdrive, Low power
mode
-
225
370
ns
Enable to ready delay
Fast mode
-
1
2
µs
Enable to ready delay
Low power mode
-
12
19
µs
INL(3)
-1.4
0.75
+1.4
LSB
DNL(3)
-0.9
0.25
+0.9
LSB
Offset Error (1)(2)
-0.200
0.260
+0.920
LSB
Gain Error (1)(2)
-0.89
0.215
0.89
LSB
Conditions
Min.
Typ.
Max.
Units
Over voltage and [-40°C, +85°C]
1.08
1.1
1.12
Over voltage at 25°C
1.09
1.1
1.11
Offset
I
Hysteresis
Propagation delay
tSTARTUP
VSCALE
Notes:
1.
2.
3.
Startup time
According to the standard equation V(X)=VLSB*(X+1); VLSB=VDDANA/64
Data computed with the Best Fit method
Data computed using histogram
32.9.7 Bandgap Reference Characteristics
Table 32-28. Bandgap (Internal 1.1V reference) characteristics
Symbol
Parameter
INTBG
Bandgap reference
V
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32.9.8 Temperature Sensor Characteristics
32.9.8.1 Temperature Sensor Characteristics
Table 32-29. Temperature Sensor Characteristics(1)
Symbol
Parameter
Conditions
Temperature sensor output
voltage
I
T= 25°C, VDDANA = 3.3V
Min.
Typ.
Max.
Units
-
0.667
-
V
2.3
2.4
2.5
mV/°C
I
Temperature sensor slope
I
Variation over VDDANA voltage
VDDANA=1.62V to 3.6V
-1.7
1
3.7
mV/V
Temperature Sensor
accuracy
Using the method described in
Section 32.9.8.2
-10
-
10
°C
Note:
1.
2.
These values are based on characterization. These values are not covered by test limits in production.
See also rev C errata concerning the temperature sensor.
32.9.8.2 Software-based Refinement of the Actual Temperature
The temperature sensor behavior is linear but it depends on several parameters such as the internal voltage reference
which itself depends on the temperature. To take this into account, each device contains a Temperature Log row with
data measured and written during the production tests. These calibration values should be read by software to infer the
most accurate temperature readings possible.
This Software Temperature Log row can be read at address 0x00806030. The Software Temperature Log row cannot be
written.
This section specifies the Temperature Log row content and explains how to refine the temperature sensor output using
the values in the Temperature Log row.
Temperature Log Row
All values in this row were measured in the following conditions:
z
VDDIN = VDDIO = VDDANA = 3.3V
z
ADC Clock frequency = 3.5MHz
z
ADC sample rate: 125ksps
z
ADC sampling time: 57µs
z
ADC mode: Free running mode, ADC averaging mode with 4 averaged samples
z
Data computed on the average of 10 ADC conversions
z
ADC voltage reference= 1.0V internal reference (aka INT1V)
z
ADC input = temperature sensor
Table 32-30. Temperature Log Row Content
Bit Position
Name
Description
7:0
ROOM_TEMP_VAL_INT
Integer part of room temperature in °C
11:8
ROOM_TEMP_VAL_DEC
Decimal part of room temperature
19:12
HOT_TEMP_VAL_INT
Integer part of hot temperature in °C
23:20
HOT_TEMP_VAL_DEC
Decimal part of hot temperature
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Table 32-30. Temperature Log Row Content (Continued)
Bit Position
Name
Description
31:24
ROOM_INT1V_VAL
2’s complement of the internal 1V reference drift at room
temperature (versus a 1.0 centered value)
39:32
HOT_INT1V_VAL
2’s complement of the internal 1V reference drift at hot
temperature (versus a 1.0 centered value)
51:40
ROOM_ADC_VAL
12bit ADC conversion at room temperature
63:52
HOT_ADC_VAL
12bit ADC conversion at hot temperature
The temperature sensor values are logged during test production flow for Room and Hot insertions:
z
ROOM_TEMP_VAL_INT and ROOM_TEMP_VAL_DEC contains the measured temperature at room
insertion (e.g. for ROOM_TEMP_VAL_INT=25 and ROOM_TEMP_VAL_DEC=2, the measured
temperature at room insertion is 25.2°C).
z
HOT_TEMP_VAL_INT and HOT_TEMP_VAL_DEC contains the measured temperature at hot insertion
(e.g. for HOT_TEMP_VAL_INT=83 and HOT_TEMP_VAL_DEC=3, the measured temperature at room
insertion is 83.3°C).
The temperature log row also contains the corresponding 12bit ADC conversions of both Room and Hot temperatures:
z
ROOM_ADC_VAL contains the 12bit ADC value corresponding to (ROOM_TEMP_VAL_INT,
ROOM_TEMP_VAL_DEC)
z
HOT_ADC_VAL contains the 12bit ADC value corresponding to (HOT_TEMP_VAL_INT,
HOT_TEMP_VAL_DEC)
The temperature log row also contains the corresponding 1V internal reference of both Room and Hot temperatures:
z
ROOM_INT1V_VAL is the 2’s complement of the internal 1V reference value corresponding to
(ROOM_TEMP_VAL_INT, ROOM_TEMP_VAL_DEC)
z
HOT_INT1V_VAL is the 2’s complement of the internal 1V reference value corresponding to
(HOT_TEMP_VAL_INT, HOT_TEMP_VAL_DEC)
z
ROOM_INT1V_VAL and HOT_INT1V_VAL values are centered around 1V with a 0.001V step. In other
words, the range of values [0,127] corresponds to [1V, 0.873V] and the range of values [-1, -127]
corresponds to [1.001V, 1.127V]. INT1V == 1 - (VAL/1000) is valid for both ranges.
Using Linear Interpolation
For concise equations, we’ll use the following notations:
z
(ROOM_TEMP_VAL_INT, ROOM_TEMP_VAL_DEC) is denoted tempR
z
(HOT_TEMP_VAL_INT, HOT_TEMP_VAL_DEC) is denoted tempH
z
ROOM_ADC_VAL is denoted ADCR, its conversion to Volt is denoted VADCR
z
HOT_ADC_VAL is denoted ADCH, its conversion to Volt is denoted VADCH
z
ROOM_INT1V_VAL is denoted INT1VR
z
HOT_INT1V_VAL is denoted INT1VH
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Using the (tempR, ADCR) and (tempH, ADCH) points, using a linear interpolation we have the following equation:
V ADCH – V ADCR⎞
ADC – V ADCR⎞
⎛V
---------------------------------- = ⎛ -------------------------------------⎝ temp – temp R ⎠
⎝ temp H – temp R ⎠
Given a temperature sensor ADC conversion value ADCm, we can infer a coarse value of the temperature tempC as:
[Equation 1]
temp C
INT1V ⎫
⎧⎛
1
-⎞ – ⎛ ADC R ⋅ --------------------R-⎞ ⎬ ⋅ ( temp H – temp R )
⎨ ⎝ ADC m ⋅ -------------------12
12
⎠ ⎝
⎠
(2 – 1)
(2 – 1) ⎭
⎩
---------------------------------------------------------------------------------------------------------------------------------------------------------= temp R +
INT1V H ⎞ ⎛
INT1V ⎫
⎧⎛
- – ADC R ⋅ --------------------R-⎞ ⎬
⎨ ⎝ ADC H ⋅ -------------------12
12
⎠ ⎝
⎠
(2 – 1)
(2 – 1) ⎭
⎩
Note 1: in the previous expression, we’ve added the conversion of the ADC register value to be expressed in V
Note 2: this is a coarse value because we assume INT1V=1V for this ADC conversion.
Using the (tempR, INT1VR) and (tempH, INT1VH) points, using a linear interpolation we have the following equation:
INT1V H – INT1V R⎞
– INT1V
⎛ INT1V
------------------------------------------R-⎞ = ⎛ ---------------------------------------------⎝ temp – temp R ⎠
⎝ temp H – temp R ⎠
Then using the coarse temperature value, we can infer a closer to reality INT1V value during the ADC conversion as:
( INT1V H – INT1V R ) ⋅ ( temp C – temp R )
INT1V m = INT1V R + ⎛ --------------------------------------------------------------------------------------------------⎞
⎝
⎠
( temp H – temp R )
Back to [Equation 1], we replace INT1V=1V by INT1V = INT1Vm, we can then deduce a finer temperature value as:
[Equation 1bis]
INT1V m ⎞ ⎛
INT1V ⎫
⎧⎛
- – ADC R ⋅ --------------------R-⎞ ⎬ ⋅ ( temp H – temp R )
⎨ ⎝ ADC m ⋅ -------------------12
12
⎠ ⎝
⎠
(2 – 1)
(2 – 1) ⎭
⎩
temp f = temp R + ---------------------------------------------------------------------------------------------------------------------------------------------------------INT1V H ⎞ ⎛
INT1V ⎫
⎧⎛
- – ADC R ⋅ --------------------R-⎞ ⎬
⎨ ⎝ ADC H ⋅ -------------------12
12
⎠ ⎝
⎠
(2 – 1)
(2 – 1) ⎭
⎩
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32.10 NVM Characteristics
Table 32-31. Maximum Operating Frequency
VDD range
NVM Wait States
Maximum Operating Frequency
0
14
1
28
2
42
3
48
0
24
1
48
Units
1.62V to 2.7V
MHz
2.7V to 3.63V
Note that on this flash technology, a max number of 8 consecutive write is allowed per row. Once this number is reached,
a row erase is mandatory.
Table 32-32. Flash Endurance and Data Retention
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
RetNVM25k
Retention after up to 25k
Average ambient 55°C
10
50
-
Years
RetNVM2.5k
Retention after up to 2.5k
Average ambient 55°C
20
100
-
Years
RetNVM100
Retention after up to 100
Average ambient 55°C
25
>100
-
Years
CycNVM
Cycling Endurance(1)
-40°C < Ta < 85°C
25k
150k
-
Cycles
Min.
Typ.
Max.
Units
Note:
1.
An endurance cycle is a write and an erase operation.
Table 32-33. EEPROM Emulation(1) Endurance and Data Retention
Symbol
Parameter
Conditions
RetEEPROM100k
Retention after up to 100k
Average ambient 55°C
10
50
-
Years
RetEEPROM10k
Retention after up to 10k
Average ambient 55°C
20
100
-
Years
CycEEPROM
Cycling Endurance(2)
-40°C < Ta < 85°C
100k
600k
-
Cycles
Min.
Typ.
Max.
Units
Notes:
1.
2.
The EEPROM emulation is a software emulation described in the App note AT03265.
An endurance cycle is a write and an erase operation.
Table 32-34. NVM Characteristics
Symbol
Parameter
Conditions
tFPP
Page programming time
-
-
-
2.5
ms
tFRE
Row erase time
I
-
-
-
6
ms
tFCE
DSU chip erase time
(CHIP_ERASE)
-
-
-
240
ms
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32.11 Oscillators Characteristics
32.11.1 Crystal Oscillator (XOSC) Characteristics
32.11.1.1 Digital Clock Characteristics
The following table describes the characteristics for the oscillator when a digital clock is applied on XIN.
Table 32-35. Digital Clock Characteristics
Symbol
fCPXIN
Parameter
Conditions
XIN clock frequency
I
Min.
Typ.
Max.
Units
-
-
32
MHz
32.11.1.2 Crystal Oscillator Characteristics
The following table describes the characteristics for the oscillator when a crystal is connected between XIN and XOUT as
shown in Figure 32-6. The user must choose a crystal oscillator where the crystal load capacitance CL is within the range
given in the table. The exact value of CL can be found in the crystal datasheet. The capacitance of the external capacitors
(CLEXT) can then be computed as follows:
C LEXT = 2 ( C L – C STRAY – C SHUNT )
where CSTRAY is the capacitance of the pins and PCB, CSHUNT is the shunt capacitance of the crystal.
Table 32-36. Crystal Oscillator Characteristics
Symbol
fOUT
ESR
CXIN
Parameter
Min.
Typ.
Max.
Units
0.4
-
32
MHz
f = 0.455MHz, CL = 100pF
XOSC.GAIN = 0
-
-
5.6K
f = 2MHz, CL = 20pF
XOSC.GAIN = 0
-
-
416
Crystal Equivalent Series
Resistance
Safety Factor = 3
f = 4MHz, CL = 20pF
XOSC.GAIN = 1
-
-
243
The AGC doesn’t have any
noticeable impact on these
measurements.
f = 8MHz, CL = 20pF
XOSC.GAIN = 2
-
-
138
f = 16MHz, CL = 20pF
XOSC.GAIN = 3
-
-
66
f = 32MHz, CL = 18pF
XOSC.GAIN = 4
-
-
56
-
5.9
-
pF
-
3.2
-
pF
Crystal oscillator frequency
Conditions
I
Parasitic capacitor load
Ω
I
CXOUT
Parasitic capacitor load
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Table 32-36. Crystal Oscillator Characteristics (Continued)
Symbol
Parameter
Conditions
Current Consumption
tSTARTUP
Startup time
Min.
Typ.
Max.
f = 2MHz, CL = 20pF, AGC off
27
65
85
f = 2MHz, CL = 20pF, AGC on
14
52
73
f = 4MHz, CL = 20pF, AGC off
61
117
150
f = 4MHz, CL = 20pF, AGC on
23
74
100
f = 8MHz, CL = 20pF, AGC off
131
226
296
f = 8MHz, CL = 20pF, AGC on
56
128
172
f = 16MHz, CL = 20pF, AGC off
305
502
687
f = 16MHz, CL = 20pF, AGC on
116
307
552
f = 32MHz, CL = 18pF, AGC off
1031
1622
2200
f = 32MHz, CL = 18pF, AGC on
278
615
1200
f = 2MHz, CL = 20pF,
XOSC.GAIN = 0, ESR = 600Ω
-
14K
48K
f = 4MHz, CL = 20pF,
XOSC.GAIN = 1, ESR = 100Ω
-
6800
19.5K
f = 8MHz, CL = 20pF,
XOSC.GAIN = 2, ESR = 35Ω
-
5550
13K
f = 16MHz, CL = 20pF,
XOSC.GAIN = 3, ESR = 25Ω
-
6750
14.5K
f = 32MHz, CL = 18pF,
XOSC.GAIN = 4, ESR = 40Ω
-
5.3K
9.6K
Units
µA
cycles
Figure 32-6. Oscillator Connection
Xin
C LEXT
Crystal
LM
C SHUNT
RM
C STRAY
CM
Xout
C LEXT
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32.11.2 External 32kHz Crystal Oscillator (XOSC32K) Characteristics
32.11.2.1 Digital Clock Characteristics
The following table describes the characteristics for the oscillator when a digital clock is applied on XIN32 pin.
Table 32-37. Digital Clock Characteristics
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
fCPXIN32
XIN32 clock frequency
I
-
32.768
-
kHz
I
XIN32 clock duty cycle
I
-
50
-
%
32.11.2.2 Crystal Oscillator Characteristics
Figure 32-6 and the equation in “Crystal Oscillator Characteristics” on page 596 also applies to the 32kHz oscillator
connection. The user must choose a crystal oscillator where the crystal load capacitance CL is within the range given in
the table. The exact value of CL can be found in the crystal datasheet.
Table 32-38. 32kHz Crystal Oscillator Characteristics
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
fOUT
Crystal oscillator frequency
I
-
32768
-
Hz
tSTARTUP
Startup time
ESRXTAL = 39.9kΩ, CL = 12.5pF
-
28K
30K
cycles
CL
Crystal load capacitance
I
-
-
12.5
CSHUNT
Crystal shunt capacitance
I
-
0.1
-
CXIN32
Parasitic capacitor load
-
3.1
-
CXOUT32
Parasitic capacitor load
-
3.3
-
AGC off
-
1.22
2.19
IXOSC32K
Current consumption
AGC on(1)
-
-
-
ESR
Crystal equivalent series
resistance f=32.768kHz
Safety Factor = 3
CL=12.5pF
-
-
141
kΩ
Min.
Typ.
Max.
Units
47
48
49
MHz
0.732
32.768
35.1
kHz
-
-
0.42
ns
Note:
pF
TQFP64/48/32 packages
1.
µA
See revD/revC/revB errata concerning the XOSC32K.
32.11.3 Digital Frequency Locked Loop (DFLL48M) Characteristics
Table 32-39. DFLL48M Characteristics - Closed Loop Mode(1)(2)
Symbol
Parameter
Conditions
fOUT
Average Output frequency
I
fREF = 32.768kHz
fREF
Reference frequency
I
Jitter
Period jitter
fREF = 32.768kHz
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Symbol
Parameter
Conditions
If
REF = 32.768kHz. For
SAMD20 revC devices
IDFLL
Power consumption on VDDIN
Lock time
1.
2.
Max.
-
397
-
Units
µA
-
292
-
fREF = 32.768kHz
DFLLVAL.COARSE =
DFLL48M COARSE CAL
DFLLVAL.FINE = 512
DFLLCTRL.BPLCKC = 1
DFLLCTRL.QLDIS = 0
DFLLCTRL.CCDIS = 1
DFLLMUL.FSTEP = 10
100
200
500
Quick lock disabled,
Chill cycle disabled,
CSTEP=3,FSTEP=1,
fREF = 32.768kHz
Note:
Typ.
fREF = 32.768kHz. For
SAMD20 revD and later.
I
tLOCK
Min.
µs
-
600
-
See revC/revB errata concerning the DFLL48M.
All parts are tested in production to be able to use the DFLL as main CPU clock whether in DFLL closed loop mode with an external OSC reference
or in DFLL closed loop mode using the internal OSC8M.
32.11.4 32.768kHz Internal oscillator (OSC32K) Characteristics
Table 32-40. 32kHz RC Oscillator Characteristics
Symbol
fOUT
Parameter
Output frequency
Conditions
Min.
Typ.
Max.
Calibrated against a 32.768kHz
reference at 25°C, over [-40, +85]°C,
over [1.62, 3.63]V
28.508
32.768
34.734
Calibrated against a 32.768kHz
reference at 25°C, at VDD=3.3V
32.276
32.768
33.260
Calibrated against a 32.768kHz
reference at 25°C, over [1.62, 3.63]V
31.457
32.768
34.079
Units
kHz
IOSC32K
Current consumption
I
-
0.67
1.31
µA
tSTARTUP
Startup time
I
-
1
2
cycle
Duty
Duty Cycle
I
-
50
-
%
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32.11.5 Ultra Low Power Internal 32kHz RC Oscillator (OSCULP32K) Characteristics
Table 32-41. Ultra Low Power Internal 32kHz RC Oscillator Characteristics
Symbol
fOUT
Parameter
Output frequency
Conditions
Min.
Typ.
Max.
Calibrated against a 32.768kHz
reference at 25°C, over [-40, +85]C,
over [1.62, 3.63]V
25.559
32.768
38.011
Calibrated against a 32.768kHz
reference at 25°C, at VDD=3.3V
31.293
32.768
34.570
Calibrated against a 32.768kHz
reference at 25°C, over
[1.62, 3.63]V
31.293
32.768
34.570
-
-
125
nA
iOSCULP32K
(1)(2)
Units
kHz
tSTARTUP
Startup time
I
-
10
-
cycles
Duty
Duty Cycle
I
-
50
-
%
Units
Notes:
1.
2.
These values are based on simulation. These values are not covered by test limits in production or characterization.
This oscillator is always on.
32.11.6 8MHz RC Oscillator (OSC8M) Characteristics
Table 32-42. Internal 8MHz RC Oscillator Characteristics
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Calibrated against a 8MHz reference
at 25°C, over [-40, +85]C, over
[1.62, 3.63]V
7.8
8
8.16
Calibrated against a 8MHz reference
at 25°C, at VDD=3.3V
7.94
8
8.06
Calibrated against a 8MHz reference
at 25°C, over [1.62, 3.63]V
7.92
8
8.08
34.5
71
96
µA
I
fOUT
Output frequency
MHz
IOSC8M
Current consumption
IDLE2 on OSC32K versus IDLE2 on
calibrated OSC8M enabled at 8MHz
(FRANGE=1, PRESC=0)
tSTARTUP
Startup time
I
-
2.1
3
µs
Duty
Duty cycle
I
-
50
-
%
I DLE
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32.12 PTC Typical Characteristics
Figure 32-7. Power consumption [µA].
1 sensor, noise countermeasures disabled, f=48MHz, Vcc=3.3V
140
120
100
80
Scan rate 10ms
60
Scan rate 50ms
40
Scan rate 100ms
Scan rate 200ms
20
0
1
2
4
8
16
32
64
Sample averaging
Figure 32-8. Power consumption [µA].
1 sensor, noise countermeasures Enabled, f=48MHz, Vcc=3.3V
200
180
160
140
120
Scan rate 10ms
100
80
Scan rate 50ms
60
Scan rate 100ms
40
Scan rate 200ms
20
0
1
2
4
8
16
32
64
Sample averaging
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Figure 32-9. Power consumption [µA].
10 sensors, noise countermeasures disabled, f=48MHz, Vcc=3.3V
1200
1000
800
Scan rate 10ms
600
Scan rate 50ms
Scan rate 100ms
400
Scan rate 200ms
200
Linear (Scan rate 50ms)
0
1
2
4
8
16
32
64
Sample averaging
Figure 32-10.Power consumption [µA].
10 sensors, noise countermeasures Enabled, f=48MHz, Vcc=3.3V
900
800
700
600
500
Scan rate 10ms
400
Scan rate 50ms
300
Scan rate 100ms
200
Scan rate 200ms
100
0
1
2
4
8
16
32
64
Sample averaging
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Figure 32-11.Power consumption [µA].
100 sensors, noise countermeasures disabled, f=48MHz, Vcc=3.3V
5000
4500
4000
3500
3000
Scan rate 10ms
2500
2000
Scan rate 50ms
1500
Scan rate 100ms
1000
Scan rate 200ms
500
0
1
2
4
8
16
32
64
Sample averaging
Figure 32-12.Power consumption [µA].
100 sensors, noise countermeasures Enabled, f=48MHz, Vcc=3.3V
1800
1600
1400
1200
1000
Scan rate 10ms
800
Scan rate 50ms
600
Scan rate 100ms
400
Scan rate 200ms
200
0
1
2
4
8
16
32
64
Sample averaging
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Figure 32-13.CPU utilization.
80 %
70 %
60 %
50 %
Channel count 1
40 %
Channel count 10
30 %
Channel count 100
20 %
10 %
0%
10
50
100
200
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32.13 Timing Characteristics
32.13.1 External Reset
Table 32-43. External reset characteristics
Symbol
tEXT
Parameter
Condition
Minimum reset pulse width
I
Min.
Typ.
Max.
Units
10
-
-
ns
32.13.2 SERCOM in SPI Mode Timing
Figure 32-14.SPI timing requirements in master mode
SS
tSCKR
tMOS
tSCKF
SCK
(CPOL = 0)
tSCKW
SCK
(CPOL = 1)
tSCKW
tMIS
MISO
(Data Input)
tMIH
tSCK
MSB
LSB
tMOH
tMOH
MOSI
(Data Output)
MSB
LSB
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Figure 32-15.SPI timing requirements in slave mode
SS
tSSCKR
tSSS
tSSCKF
tSSH
SCK
(CPOL = 0)
tSSCKW
SCK
(CPOL = 1)
tSSCKW
tSIS
MOSI
(Data Input)
tSIH
MSB
tSOSS
MISO
(Data Output)
tSSCK
LSB
tSOS
MSB
tSOSH
LSB
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Table 32-44. SPI timing characteristics and requirements(1)
Symbol
Parameter
Conditions
Min.
Typ.
Max.
tSCK
SCK period
Master
tSCKW
SCK high/low width
Master
-
0.5*tSCK
-
tSCKR
SCK rise time(2)
Master
-
-
-
tSCKF
SCK fall time(2)
Master
-
-
-
tMIS
MISO setup to SCK
Master
-
29
-
tMIH
MISO hold after SCK
Master
-
8
-
tMOS
MOSI setup SCK
Master
-
tSCK/2 - 16
-
tMOH
MOSI hold after SCK
Master
-
16
-
tSSCK
Slave SCK Period
Slave
1*tCLK_APB
-
-
tSSCKW
SCK high/low width
Slave
0.5*tSSCK
-
-
tSSCKR
SCK rise time(2)
Slave
-
-
-
tSSCKF
SCK fall time(2)
Slave
-
-
-
tSIS
MOSI setup to SCK
Slave
tSSCK/2 - 19
-
-
tSIH
MOSI hold after SCK
Slave
tSSCK/2 - 5
-
-
PRELOADEN=1
-
SS setup to SCK
Slave
2*tCLK_APB
+ tSOS
-
tSSS
PRELOADEN=0
tSOS+7
-
-
84
tSSH
SS hold after SCK
Slave
tSIH - 4
-
-
tSOS
MISO setup SCK
Slave
-
tSSCK/2 - 20
-
tSOH
MISO hold after SCK
Slave
-
20
-
tSOSS
MISO setup after SS low
Slave
-
16
-
tSOSH
MISO hold after SS high
Slave
-
11
-
Notes:
1.
2.
Units
ns
These values are based on simulation. These values are not covered by test limits in production.
See “I/O Pin Characteristics” on page 580
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32.13.3 SERCOM in I2C Mode Timing
Table 32-45 describes the requirements for devices connected to the I2C Interface Bus. Timing symbols refer to Figure
32-16.
Figure 32-16. I2C Interface Bus Timing
tOF
tHIGH
tR
tLOW
tLOW
SCL
tSU;STA
tHD;STA
tHD;DAT
tSU;DAT
tSU;STO
SDA
tBUF
Table 32-45. I2C Interface Timing(1)
Symbol
Parameter
Conditions
Min.
Typ.
Max.
-
-
300
tR
Rise time for both SDA and SCL(3)
I
tOF
Output fall time from VIHmin to VILmax (3)
10pF < Cb(2) < 400pF
7.0
10.0
50.0
tHD;STA
Hold time (repeated) START condition
fSCL > 100kHz, Master
tLOW-9
-
-
tLOW
Low period of SCL Clock
fSCL > 100kHz
113
-
-
tBUF
Bus free time between a STOP and a
START condition
fSCL > 100kHz
tLOW
-
-
tSU;STA
Setup time for a repeated START condition
fSCL > 100kHz, Master
tLOW+7
-
-
tHD;DAT
Data hold time
fSCL > 100kHz, Master
9
-
12
tSU;DAT
Data setup time
fSCL > 100kHz, Master
104
-
-
tSU;STO
Setup time for STOP condition
fSCL > 100kHz, Master
tLOW+9
-
-
tSU;DAT;rx
Data setup time (receive mode)
fSCL > 100kHz, Slave
51
-
56
tHD;DAT;tx
Data hold time (send mode)
fSCL > 100kHz, Slave
71
90
138
Notes:
1.
2.
3.
Units
ns
These values are based on simulation. These values are not covered by test limits in production.
Cb = Capacitive load on each bus line. Otherwise noted, value of Cb set to 20pF.
These values are based on characterization. These values are not covered by test limits in production.
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32.13.4 SWD Timing
Figure 32-17.SWD Interface Signals
Read Cycle
From debugger to
SWDIO pin
Stop
Park
Tri State
Thigh
Tos
Data
Data
Parity
Start
Tlow
From debugger to
SWDCLK pin
SWDIO pin to
debugger
Tri State
Acknowledge
Tri State
Write Cycle
From debugger to
SWDIO pin
Stop
Park
Tri State
Tis
Start
Tih
From debugger to
SWDCLK pin
SWDIO pin to
debugger
Tri State
Acknowledge
Data
Data
Parity
Tri State
Table 32-46. SWD Timings(1)
Symbol
Parameter
Conditions
Min.
Max.
Thigh
SWDCLK High period
10
500000
Tlow
SWDCLK Low period
10
500000
Tos
SWDIO output skew to falling edge
SWDCLK
-5
5
Tis
Input Setup time required between
SWDIO
Tih
Input Hold time required between
SWDIO and rising edge SWDCLK
Note:
1.
VVDDIO from 3.0V to 3.6V,
maximum external capacitor =
40pF
Units
ns
4
-
1
-
These values are based on simulation. These values are not covered by test limits in production or characterization.
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33.
Packaging Information
33.1
Thermal Considerations
33.1.1 Thermal Resistance Data
Table 33-1 summarizes the thermal resistance data depending on the package.
Table 33-1. Thermal Resistance Data
Package Type
θJA
θJC
32-pin TQFP
68°C/W
25.8°C/W
48-pin TQFP
78.8°C/W
12.3°C/W
64-pin TQFP
66.7°C/W
11.9°C/W
32-pin QFN
37.2°C/W
3.1°C/W
48-pin QFN
33°C/W
11.4°C/W
64-pin QFN
33.5°C/W
11.2°C/W
64-ball UFBGA
67.4°C/W
12.4°C/W
45-ball WLCSP
37.0°C/W
0.36°C/W
33.1.2 Junction Temperature
The average chip-junction temperature, TJ, in °C can be obtained from the following equations:
Equation 1
T J = T A + ( P D × θ JA )
Equation 2
T J = T A + ( P D × ( θ HEATSINK + θ JC ) )
where:
z
θJA = package thermal resistance, Junction-to-ambient (°C/W), provided in Table 33-1
z
θJC = package thermal resistance, Junction-to-case thermal resistance (°C/W), provided in Table 33-1
z
θHEATSINK = cooling device thermal resistance (°C/W), provided in the manufacturer datasheet
z
PD = device power consumption (W)
z
TA = ambient temperature (°C)
From “Equation 1” , the user can derive the estimated lifetime of the chip and decide if a cooling device is necessary or
not. If a cooling device is to be fitted on the chip, “Equation 2” should be used to compute the resulting average chipjunction temperature TJ in °C.
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33.2
Package Drawings
33.2.1 64-pin TQFP
Table 33-2. Device and Package Maximum Weight
300
mg
Table 33-3. Package Characteristics
Moisture Sensitivity Level
MSL3
Table 33-4. Package Reference
JEDEC Drawing Reference
MS-026
JESD97 Classification
E3
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33.2.2 64-pin QFN
Note:
The exposed die attached pad is not connected inside the device.
Table 33-5. Device and Package Maximum Weight
200
mg
Table 33-6. Package Characteristics
Moisture Sensitivity Level
MSL3
Table 33-7. Package Reference
JEDEC Drawing Reference
MO-220
JESD97 Classification
E3
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33.2.3 64-ball UFBGA
Table 33-8. Device and Package Maximum Weight
27.4
mg
Table 33-9. Package Characteristics
Moisture Sensitivity Level
MSL3
Table 33-10. Package Reference
JEDEC Drawing Reference
MO-280
JESD97 Classification
E8
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33.2.4 48-pin TQFP
Table 33-11. Device and Package Maximum Weight
140
mg
Table 33-12. Package Characteristics
Moisture Sensitivity Level
MSL3
Table 33-13. Package Reference
JEDEC Drawing Reference
MS-026
JESD97 Classification
E3
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33.2.5 48-pin QFN
Note:
The exposed die attached pad is not connected inside the device.
Table 33-14. Device and Package Maximum Weight
140
mg
Table 33-15. Package Characteristics
Moisture Sensitivity Level
MSL3
Table 33-16. Package Reference
JEDEC Drawing Reference
MO-220
JESD97 Classification
E3
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33.2.6 45-ball WLCSP
Note:
The exposed die attached pad is not connected inside the device.
Table 33-17. Device and Package Maximum Weight
7.3
mg
Table 33-18. Package Characteristics
Moisture Sensitivity Level
MSL1
Table 33-19. Package Reference
JEDEC Drawing Reference
MO-220
JESD97 Classification
E1
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33.2.7 32-pin TQFP
Table 33-20. Device and Package Maximum Weight
100
mg
Table 33-21. Package Characteristics
Moisture Sensitivity Level
MSL3
Table 33-22. Package Reference
JEDEC Drawing Reference
MS-026
JESD97 Classification
E3
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33.2.8 32-pin QFN
Note:
The exposed die attached pad is connected inside the device to GND and GNDANA connected together.
Table 33-23. Device and Package Maximum Weight
90
mg
Table 33-24. Package Characteristics
Moisture Sensitivity Level
MSL3
Table 33-25. Package Reference
JEDEC Drawing Reference
MO-220
JESD97 Classification
E3
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33.3
Soldering Profile
Table Table 33-26 gives the recommended soldering profile from J-STD-20.
Table 33-26. Soldering Profile
Profile Feature
Green Package
Average Ramp-up Rate (217°C to peak)
3°C/s max.
Preheat Temperature 175°C ±25°C
150-200°C
Time Maintained Above 217°C
60-150s
Time within 5°C of Actual Peak Temperature
30s
Peak Temperature Range
260°C
Ramp-down Rate
6°C/s max
Time 25°C to Peak Temperature
8 minutes max.
A maximum of three reflow passes is allowed per component.
___REV___287606
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34.
Schematic Checklist
34.1
Introduction
A good hardware design comes from a proper schematic. This chapter describes a common checklist which should be
used when starting and reviewing the schematics for a SAM D20 design. This chapter will describe a recommended
power supply connection, how to connect external analog references, programmer, debugger, oscillator and crystal.
34.2
Power Supply
The SAM D20 supports a single power supply from 1.62 to 3.63V.
34.2.1 Power Supply Connections
Figure 34-1. Power Supply Schematic
Close to device
(for every pin)
1.62V-3.63V
VDDANA
10μF
100nF
GNDANA
VDDIO
100nF
VDDIN
100nF
10μF
VDDCORE
100nF
GND
Table 34-1. Power Supply Connections, VDDCORE From Internal Regulator
Signal Name
Recommended Pin Connection
Description
VDDIO
1.6V to 3.6V
Decoupling/filtering capacitors 100nF(1)(2) and 10µF(1)
Decoupling/filtering inductor 10µH(1)(3)
Digital supply voltage
VDDANA
1.6V to 3.6V
Decoupling/filtering capacitors 100nF(1)(2) and 10µF(1)
Ferrite bead(4) prevents the VDD noise interfering the
VDDANA
Analog supply voltage
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Table 34-1. Power Supply Connections, VDDCORE From Internal Regulator (Continued)
Signal Name
Recommended Pin Connection
Description
VDDCORE
1.6V to 1.8V
Decoupling/filtering capacitor 100nF(1)(2)
Core supply voltage / external decoupling pin
GND
Ground
GNDANA
Ground for the analog power domain
Notes:
1.
2.
3.
4.
34.3
These values are only given as typical examples.
Decoupling capacitor should be placed close to the device for each supply pin pair in the signal group, low ESR caps should be used for better
decoupling.
An inductor should be added between the external power and the VDD for power filtering.
Ferrite bead has better filtering performance than the common inductor at high frequencies. It can be added between VDD and VDDANA for preventing digital noise from entering the analog power domain. The bead should provide enough impedance (e.g. 50Ω at 20MHz and 220Ω at 100MHz)
for separating the digital power from the analog power domain. Make sure to select a ferrite bead designed for filtering applications with a low DC
resistance to avoid a large voltage drop across the ferrite bead.
External Analog Reference Connections
The following schematic checklist is only necessary if the application is using one or more of the external analog
references. If the internal references are used instead, the following circuits in Figure 34-2 and Figure 34-3 are not
necessary.
Figure 34-2. External Analog Reference Schematic With Two References
Close to device
(for every pin)
VREFA
EXTERNAL
REFERENCE 1
4.7μF
100nF
GND
VREFB
EXTERNAL
REFERENCE 2
4.7μF
100nF
GND
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Figure 34-3. External Analog Reference Schematic With One Reference
Close to device
(for every pin)
VREFA
EXTERNAL
REFERENCE
4.7μF
100nF
GND
VREFB
100nF
GND
Table 34-2. External Analog Reference Connections
Signal Name
Recommended Pin Connection
Description
VREFx
1.0V to VDDANA - 0.6V for ADC
1.0V to VDDANA - 0.6V for DAC
Decoupling/filtering capacitors
100nF(1)(2) and 4.7µF(1)
External reference from VREFx pin on
the analog port
GND
Notes:
Ground
1.
2.
These values are given as a typical example.
Decoupling capacitor should be placed close to the device for each supply pin pair in the signal group.
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34.4
External Reset Circuit
The external reset circuit is connected to the RESET pin when the external reset function is used. If the external reset
function has been disabled, the circuit is not necessary. The reset switch can also be removed, if the manual reset is not
necessary. The RESET pin itself has an internal pull-up resistor, hence it is optional to also add an external pull-up
resistor.
Figure 34-4. External Reset Circuit Example Schematic
VDD
10kΩ
330Ω
RESET
100nF
GND
A pull-up resistor makes sure that the reset does not go low unintended causing a device reset. An additional resistor has
been added in series with the switch to safely discharge the filtering capacitor, i.e. preventing a current surge when
shorting the filtering capacitor which again causes a noise spike that can have a negative effect on the system.
Table 34-3. Reset Circuit Connections
Signal Name
Recommended Pin Connection
Description
RESET
Reset low level threshold voltage
VDDIO = 1.6V - 2.0V: Below 0.33 * VDDIO
VDDIO = 2.7V - 3.6V: Below 0.36 * VDDIO
Decoupling/filter capacitor 100nF(1)
Pull-up resistor 10kΩ(1)(2)
Resistor in series with the switch 330Ω(1)
Reset pin
Notes:
34.5
1.
2.
These values are given as a typical example.
The SAM D20 features an internal pull-up resistor on the RESET pin, hence an external pull-up is optional.
Unused or Unconnected Pins
Unused or unconnected pins (unless marked as NC where applicable) should not be left unconnected and floating.
Floating pins will add to the overall power consumption of the device. To prevent this one should always draw the pin
voltage towards a given level, either VDD or GND, through a pull up/down resistor. External or internal pull up/down
resistors can be used, e.g. the pins can be configured in pull-up or pull-down mode eliminating the need for external
components, for more information see “PORT” on page 287 for details. There are no obvious benefit in choosing external
vs. internal pull resistors.
34.6
Clocks and Crystal Oscillators
The SAM D20 can be run from internal or external clock sources, or a mix of internal and external sources. An example
of usage will be to use the internal 8MHz oscillator as source for the system clock, and an external 32.768kHz watch
crystal as clock source for the Real-Time counter (RTC).
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34.6.1 External Clock Source
Figure 34-5. External Clock Source Example Schematic
External
Clock
XIN
XOUT/GPIO
NC/GPIO
Table 34-4. External Clock Source Connections
Signal Name
Recommended Pin Connection
Description
XIN
XIN is used as input for an external clock signal
Input for inverting oscillator pin
XOUT/GPIO
Can be left unconnected or used as normal GPIO
34.6.2 Crystal Oscillator
Figure 34-6. Crystal Oscillator Example Schematic
XIN
15pF
XOUT
15pF
The crystal should be located as close to the device as possible. Long signal lines may cause too high load to operate
the crystal, and cause crosstalk to other parts of the system.
Table 34-5. Crystal Oscillator Checklist
Signal Name
Recommended Pin Connection
XIN
Load capacitor 15pF(1)(2)
XOUT
Load capacitor 15pF(1)(2)
Notes:
1.
2.
Description
External crystal between 0.4 to 30MHz
These values are given only as typical example.
Decoupling capacitor should be placed close to the device for each supply pin pair in the signal group.
34.6.3 External Real Time Oscillator
The low frequency crystal oscillator is optimized for use with a 32.768kHz watch crystal. When selecting crystals, load
capacitance and crystal’s Equivalent Series Resistance (ESR) must be taken into consideration. Both values are
specified by the crystal vendor.
SAM D20 oscillator is optimized for very low power consumption, hence close attention should be made when selecting
crystals, see Table 34-6 for maximum ESR recommendations on 9pF and 12.5pF crystals.
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The Low-frequency Crystal Oscillator provides an internal load capacitance of typical 3.05pF and 3.29pF. Crystals with
recommended 12.5pF load capacitance can be without external capacitors as shown in Figure 34-7.
Table 34-6. Maximum ESR Recommendation for 32.768kHz Crystal
Crystal CL (pF)
Max ESR [kΩ]
12.5
313
Note:
Maximum ESR is typical value based on characterization. These values are not covered by test limits in production.
Figure 34-7. External Real Time Oscillator without Load Capacitor
XIN32
32.768kHz
XOUT32
Crystals specifying load capacitance (CL) higher than 12.5pF, require external capacitors applied as described in Figure
34-8.
To find suitable load capacitance for a 32.768kHz crystal, consult the crystal datasheet.
Figure 34-8. External Real Time Oscillator with Load Capacitor
22pF
32.768kHz
XIN32
XOUT32
22pF
Table 34-7. External Real Time Oscillator Checklist
Signal Name
Recommended Pin Connection
(1)(2)
XIN32
Load capacitor 22pF
XOUT32
Load capacitor 22pF(1)(2)
Notes:
1.
2.
Description
Timer oscillator input
Timer oscillator output
These values are given only as typical examples.
Decoupling capacitor should be placed close to the device for each supply pin pair in the signal group.
34.6.4 Calculating the Correct Crystal Decoupling Capacitor
In order to calculate correct load capacitor for a given crystal one can use the model shown in Figure 34-9 which includes
internal capacitors CLn, external parasitic capacitance CELn and external load capacitance CPn.
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Figure 34-9. Crystal Circuit With Internal, External and Parasitic Capacitance
XIN
CEL1
Internal
CL2
XOUT
CP1
CP2
External
CL1
CEL2
Using this model the total capacitive load for the crystal can be calculated as shown in the equation below:
∑
( C L1 + C P1 + C EL1 ) ( C L2 + C P2 + C EL2 )
C tot = -------------------------------------------------------------------------------------------------------C L1 + C P1 + C EL1 + C L2 + C P2 + C EL2
where Ctot is the total load capacitance seen by the crystal, this value should be equal to the load capacitance value
found in the crystal manufacturer datasheet.
The parasitic capacitance CELn can in most applications be disregarded as these are usually very small. If accounted for
the value is dependent on the PCB material and PCB layout.
For some crystal the internal capacitive load provided by the device itself can be enough. To calculate the total load
capacitance in this case. CELn and CPn are both zero, CL1 = CL2 = CL, and the equation reduces to the following:
∑
CL
C tot = ------2
Table 34-8 shows the device equivalent internal pin capacitance.
Table 34-8. Equivalent Internal Pin Capacitance
Symbol
Value
Description
CXIN32
3.05pF
Equivalent internal pin capacitance
CXOUT32
3.29pF
Equivalent internal pin capacitance
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34.7
Programming and Debug Ports
For programming and/or debugging the SAM-ICE can be connected to the device using the Serial Wire Debug, SWD,
interface. The SAM-ICE uses a 20 pin connector to connect to the target, note that only four of the 20 pins and ground
are used. Figure 1-11 shows how the SAM-ICE should be connected to the target. For details please consult with the
SAM-ICE user manual. For connecting to any other programming or debugging tool please refer to that specific
programmer or debugger’s user guide.
The Xplained Pro evaluation board for the SAM D20 supports programming and debugging through the onboard
embedded debugger so no external programmer or debugger is needed.
34.7.1 10-way Serial Wire Debug and Trace Connector
Figure 34-10.10-way Serial Wire Debug Connections
VDD
Cortex Debug Connector
(10-pin)
VTref
1
SWDIO
GND
SWDCLK
GND
NC
NC
NC
NC
RESET
RESET
SWCLK
SWDIO
GND
For debuggers/programmers that support the 10-way ARM debug interface should be connected as shown in Figure 110 with details described in Table 1-9.
Table 34-9. 10-way Serial Wire Debug Connections
Signal Name
Description
SWDCLK
Serial wire clock pin
SWDIO
Serial wire bidirectional data pin
RESET
Target device reset pin, active low
VTref
Target voltage sense, should be connected to the device VDD
GND
Ground
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34.7.2 20-way SAM-ICE Serial Wire Debug Interface
Figure 34-11.20-way Serial Wire Debug Connections
VDD
20-pin IDC JTAG Connector
VCC
1
NC
NC
GND
NC
GND
SWDIO
GND
SWDCLK
GND
NC
GND
NC
GND*
RESET
GND*
NC
GND*
NC
GND*
RESET
SWCLK
SWDIO
GND
Table 34-10. 20-way Serial Wire Debug Connections (SAM-ICE)
Signal Name
Description
SWCLK
Serial wire clock pin
SWDIO
Serial wire bidirectional data pin
RESET
Target device reset pin, active low
VTref
Target voltage sense, should be connected to the device VDD
GND
Ground
GND*
These pins are reserved for firmware extension purposes. They can be left open or connected to GND
in normal debug environment. They are not essential for SWD in general.
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35.
Errata
35.1
Revision E
35.1.1 Device
1 - In the table ""NVM User Row Mapping"", the WDT Window bitfield default
value on silicon is not as specified in the datasheet. The datasheet defines
the default value as 0x5, while it is 0xB on silicon. Errata reference: 13951
Fix/Workaround:
None.
2 - Clock Failure detection for external OSC does not work in standby mode.
Errata reference: 12688
Fix/Workaround:
Before entering standby mode, move the CPU clock to an internal RC, disable
external OSC and disable the Clock Failure detector. Upon CPU wakeup, restart
external OSC (if it does not start, the failure occurred during standby), enable the
Clock Failure detector and move the CPU clock to the external OSC.
3 - In single shot mode and at 105°C, the ADC conversions have linearity
errors. Errata reference: 13276
Fix/Workaround:
- Workaround 1: At 105°C, do not use the ADC in single shot mode; use the
ADC in free running mode only.
- Workaround 2: At 105°C, use the ADC in single shot mode only with
VDDANA > 2.7V.
4 - If APB clock is stopped and GCLK clock is running, APB read access to
read-synchronized registers will freeze the system. The CPU and the DAP
AHB-AP are stalled, as a consequence debug operation is impossible.
Errata reference: 10416
Fix/Workaround:
Do not make read access to read-synchronized registers when APB clock is
stopped and GCLK is running. To recover from this situation, power cycle the
device or reset the device using the RESETN pin.
5 - In the table ""NVM User Row Mapping"", bits 40 & 41 default values on
silicon are not as specified in the datasheet. The datasheet defines the
default value as 0, it is 1 for both bits on silicon. Errata reference: 13950
Fix/workaround:
None.
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6 - In I2C Slave mode, writing the CTRLB register when in the AMATCH or
DRDY interrupt service routines can cause the state machine to reset. Errata
reference: 13574
Fix/Workaround:
Write CTRLB.ACKACT to 0 using the following sequence:
// If higher priority interrupts exist, then disable so that the
// following two writes are atomic.
SERCOM - STATUS.reg = 0;
SERCOM - CTRLB.reg = 0;
// Re-enable interrupts if applicable.
Write CTRLB.ACKACT to 1 using the following sequence:
// If higher priority interrupts exist, then disable so that the
// following two writes are atomic.
SERCOM - STATUS.reg = 0;
SERCOM - CTRLB.reg = SERCOM_I2CS_CTRLB_ACKACT;
// Re-enable interrupts if applicable.
Otherwise, only write to CTRLB in the AMATCH or DRDY interrupts if it is to close
out a transaction.
When not closing a transaction, clear the AMATCH interrupt by writing a 1 to its bit
position instead of using CTRLB.CMD. The DRDY interrupt is automatically
cleared by reading/writing to the DATA register in smart mode. If not in smart
mode, DRDY should be cleared by writing a 1 to its bit position.
Code replacements examples:
Current:
SERCOM - CTRLB.reg |= SERCOM_I2CS_CTRLB_ACKACT;
Change to:
// If higher priority interrupts exist, then disable so that the
// following two writes are atomic.
SERCOM - STATUS.reg = 0;
SERCOM - CTRLB.reg = SERCOM_I2CS_CTRLB_ACKACT;
// Re-enable interrupts if applicable.
Current:
SERCOM - CTRLB.reg &= ~SERCOM_I2CS_CTRLB_ACKACT;
Change to:
// If higher priority interrupts exist, then disable so that the
// following two writes are atomic.
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SERCOM - STATUS.reg = 0;
SERCOM - CTRLB.reg = 0;
// Re-enable interrupts if applicable.
Current:
/* ACK or NACK address */
SERCOM - CTRLB.reg |= SERCOM_I2CS_CTRLB_CMD(0x3);
Change to:
// CMD=0x3 clears all interrupts, so to keep the result similar,
// PREC is cleared if it was set.
if (SERCOM - INTFLAG.bit.PREC) SERCOM - INTFLAG.reg =
SERCOM_I2CS_INTFLAG_PREC;
SERCOM - INTFLAG.reg = SERCOM_I2CS_INTFLAG_AMATCH;
7 - The voltage regulator in low power mode is not functional at
temperatures above 85C. Errata reference: 12290
Fix/Workaround:
Enable normal mode on the voltage regulator in standby sleep mode.
Example code:
// Set the voltage regulator in normal mode configuration in standby sleep mode
SYSCTRL->VREG.bit.RUNSTDBY = 1;
8 - After a clock failure detection (INTFLAG.CFD = 1), if INTFLAG.CFD is
cleared while the clock is still broken, the system is stuck. Errata reference:
12687
Fix/Workaround:
After a clock failure detection, do not clear INTFLAG.CFD or perform a system
reset.
9 - If the external XOSC32K is broken, neither the external pin RST nor the
GCLK software reset can reset the GCLK generators using XOSC32K as
source clock. Errata reference: 12164
Fix/Workaround:
Do a power cycle to reset the GCLK generators after an external XOSC32K
failure.
35.1.2 XOSC32K
1 - The automatic amplitude control of the XOSC32K does not work. Errata
reference: 10933
Fix/Workaround:
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Use the XOSC32K with Automatic Amplitude control disabled
(XOSC32K.AAMPEN = 0)
35.1.3 DFLL48M
1 - The DFLL clock must be requested before being configured otherwise a
write access to a DFLL register can freeze the device. Errata reference: 9905
Fix/Workaround:
Write a zero to the DFLL ONDEMAND bit in the DFLLCTRL register before
configuring the DFLL module.
2 - If the DFLL48M reaches the maximum or minimum COARSE or FINE
calibration values during the locking sequence, an out of bounds interrupt
will be generated. These interrupts will be generated even if the final
calibration values at DFLL48M lock are not at maximum or minimum, and
might therefore be false out of bounds interrupts. Errata reference: 10669
Fix/Workaround:
Check that the lockbits: DFLLLCKC and DFLLLCKF in the SYSCTRL Interrupt
Flag Status and Clear register (INTFLAG) are both set before enabling the
DFLLOOB interrupt.
35.1.4 SERCOM
1 - In TWI master mode, an ongoing transaction should be stalled
immediately when DBGCTRL.DBGSTOP is set and the CPU enters debug
mode. Instead, it is stopped when the current byte transaction is completed
and the corresponding interrupt is triggered if enabled. Errata reference:
12499
Fix/Workaround:
In TWI master mode, keep DBGCTRL.DBGSTOP=0 when in debug mode.
35.2
Revision D
35.2.1 DSU
1 - If a debugger has issued a DSU Cold-Plugging procedure and then
released the CPU from the resulting ""CPU Reset Extension"", the CPU will
be held in ""CPU Reset Extension"" after any upcoming reset event. Errata
reference: 12015
Fix/workaround:
The CPU must be released from the ""CPU Reset Extension"" either by writing a
one in the DSU STATUSA.CRSTEXT register or by applying an external reset
with SWCLK high or by power cycling the device.
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35.2.2 NVMCTRL
1 - When the part is secured and EEPROM emulation area configured to
none, the CRC32 is not executed on the entire flash area but up to the onchip flash size minus half a row. Errata reference: 11988
Fix/Workaround:
When using CRC32 on a protected device with EEPROM emulation area
configured to none, compute the reference CRC32 value to the full chip flash size
minus half row.
35.2.3 Device
1 - When VDDIN is lower than the POR threshold during power rise or fall, an
internal pull-up resistor is enabled on pins with PTC functionality (see PORT
Function Multiplexing). Note that this behavior will be present even if PTC
functionality is not enabled on the pin. The POR level is defined in the
“Power-On Reset (POR) Characteristics” chapter. Errata reference: 10805
Fix/Workaround:
Use a pin without PTC functionality if the pull-up could damage your application
during power up.
2 - In the table ""NVM User Row Mapping"", the WDT Window bitfield default
value on silicon is not as specified in the datasheet. The datasheet defines
the default value as 0x5, while it is 0xB on silicon. Errata reference: 13951
Fix/Workaround:
None.
3 - Clock Failure detection for external OSC does not work in standby mode.
Errata reference: 12688
Fix/Workaround:
Before entering standby mode, move the CPU clock to an internal RC, disable
external OSC and disable the Clock Failure detector. Upon CPU wakeup, restart
external OSC (if it does not start, the failure occurred during standby), enable the
Clock Failure detector and move the CPU clock to the external OSC.
4 - In single shot mode and at 105°C, the ADC conversions have linearity
errors. Errata reference: 13276
Fix/Workaround:
- Workaround 1: At 105°C, do not use the ADC in single shot mode; use the
ADC in free running mode only.
- Workaround 2: At 105°C, use the ADC in single shot mode only with
VDDANA > 2.7V.
5 - If APB clock is stopped and GCLK clock is running, APB read access to
read-synchronized registers will freeze the system. The CPU and the DAP
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AHB-AP are stalled, as a consequence debug operation is impossible.
Errata reference: 10416
Fix/Workaround:
Do not make read access to read-synchronized registers when APB clock is
stopped and GCLK is running. To recover from this situation, power cycle the
device or reset the device using the RESETN pin.
6 - In the table ""NVM User Row Mapping"", bits 40 & 41 default values on
silicon are not as specified in the datasheet. The datasheet defines the
default value as 0, it is 1 for both bits on silicon. Errata reference: 13950
Fix/workaround:
None.
7 - In I2C Slave mode, writing the CTRLB register when in the AMATCH or
DRDY interrupt service routines can cause the state machine to reset. Errata
reference: 13574
Fix/Workaround:
Write CTRLB.ACKACT to 0 using the following sequence:
// If higher priority interrupts exist, then disable so that the
// following two writes are atomic.
SERCOM - STATUS.reg = 0;
SERCOM - CTRLB.reg = 0;
// Re-enable interrupts if applicable.
Write CTRLB.ACKACT to 1 using the following sequence:
// If higher priority interrupts exist, then disable so that the
// following two writes are atomic.
SERCOM - STATUS.reg = 0;
SERCOM - CTRLB.reg = SERCOM_I2CS_CTRLB_ACKACT;
// Re-enable interrupts if applicable.
Otherwise, only write to CTRLB in the AMATCH or DRDY interrupts if it is to close
out a transaction.
When not closing a transaction, clear the AMATCH interrupt by writing a 1 to its bit
position instead of using CTRLB.CMD. The DRDY interrupt is automatically
cleared by reading/writing to the DATA register in smart mode. If not in smart
mode, DRDY should be cleared by writing a 1 to its bit position.
Code replacements examples:
Current:
SERCOM - CTRLB.reg |= SERCOM_I2CS_CTRLB_ACKACT;
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Change to:
// If higher priority interrupts exist, then disable so that the
// following two writes are atomic.
SERCOM - STATUS.reg = 0;
SERCOM - CTRLB.reg = SERCOM_I2CS_CTRLB_ACKACT;
// Re-enable interrupts if applicable.
Current:
SERCOM - CTRLB.reg &= ~SERCOM_I2CS_CTRLB_ACKACT;
Change to:
// If higher priority interrupts exist, then disable so that the
// following two writes are atomic.
SERCOM - STATUS.reg = 0;
SERCOM - CTRLB.reg = 0;
// Re-enable interrupts if applicable.
Current:
/* ACK or NACK address */
SERCOM - CTRLB.reg |= SERCOM_I2CS_CTRLB_CMD(0x3);
Change to:
// CMD=0x3 clears all interrupts, so to keep the result similar,
// PREC is cleared if it was set.
if (SERCOM - INTFLAG.bit.PREC) SERCOM - INTFLAG.reg =
SERCOM_I2CS_INTFLAG_PREC;
SERCOM - INTFLAG.reg = SERCOM_I2CS_INTFLAG_AMATCH;
8 - The voltage regulator in low power mode is not functional at
temperatures above 85C. Errata reference: 12290
Fix/Workaround:
Enable normal mode on the voltage regulator in standby sleep mode.
Example code:
// Set the voltage regulator in normal mode configuration in standby sleep mode
SYSCTRL->VREG.bit.RUNSTDBY = 1;
9 - After a clock failure detection (INTFLAG.CFD = 1), if INTFLAG.CFD is
cleared while the clock is still broken, the system is stuck. Errata reference:
12687
Fix/Workaround:
After a clock failure detection, do not clear INTFLAG.CFD or perform a system
reset.
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10 - In Standby, Idle1 and Idle2 sleep modes the device might not wake up
from sleep. An External Reset, Power on Reset or Watch Dog Reset will start
the device again. Errata reference: 13140
Fix/Workaround:
the SLEEPPRM bits in the NVMCTRL.CTRLB register must be written to 3
(NVMCTRL - CTRLB.bit.SLEEPPRM = 3) to ensure correct operation of the
device. The average power consumption of the device will increase with 20uA
compared to numbers in the electrical characteristics chapter.
11 - Digital pin outputs from Timer/Counters, AC (Analog Comparator),
GCLK (Generic Clock Controller), and SERCOM (I2C and SPI) do not change
value during standby sleep mode. Errata reference: 12537
Fix/Workaround:
Set the voltage regulator in Normal mode before entering STANDBY sleep mode
in order to keep digital pin output enabled. This is done by setting the RUNSTDBY
bit in the VREG register.
12 - If the external XOSC32K is broken, neither the external pin RST nor the
GCLK software reset can reset the GCLK generators using XOSC32K as
source clock. Errata reference: 12164
Fix/Workaround:
Do a power cycle to reset the GCLK generators after an external XOSC32K
failure.
35.2.4 PM
1 - In debug mode, if a watchdog reset occurs, the debug session is lost.
Errata reference: 12196
Fix/Workaround:
A new debug session must be restart after a watchdog reset.
35.2.5 XOSC32K
1 - The automatic amplitude control of the XOSC32K does not work. Errata
reference: 10933
Fix/Workaround:
Use the XOSC32K with Automatic Amplitude control disabled
(XOSC32K.AAMPEN = 0)
35.2.6 DFLL48M
1 - The DFLL clock must be requested before being configured otherwise a
write access to a DFLL register can freeze the device. Errata reference: 9905
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Fix/Workaround:
Write a zero to the DFLL ONDEMAND bit in the DFLLCTRL register before
configuring the DFLL module.
2 - If the DFLL48M reaches the maximum or minimum COARSE or FINE
calibration values during the locking sequence, an out of bounds interrupt
will be generated. These interrupts will be generated even if the final
calibration values at DFLL48M lock are not at maximum or minimum, and
might therefore be false out of bounds interrupts. Errata reference: 10669
Fix/Workaround:
Check that the lockbits: DFLLLCKC and DFLLLCKF in the SYSCTRL Interrupt
Flag Status and Clear register (INTFLAG) are both set before enabling the
DFLLOOB interrupt.
35.2.7 SERCOM
1 - In TWI master mode, an ongoing transaction should be stalled
immediately when DBGCTRL.DBGSTOP is set and the CPU enters debug
mode. Instead, it is stopped when the current byte transaction is completed
and the corresponding interrupt is triggered if enabled. Errata reference:
12499
Fix/Workaround:
In TWI master mode, keep DBGCTRL.DBGSTOP=0 when in debug mode.
35.2.8 TC
1 - Spurious TC overflow and Match/Capture events may occur. Errata
reference: 13268
Fix/Workaround:
Do not use the TC overflow and Match/Capture events. Use the corresponding
Interrupts instead.
35.2.9 PTC
1 - WCOMP interrupt flag is not stable. The WCOMP interrupt flag will not
always be set as described in the datasheet. Errata reference: 12860
Fix/Workaround:
Do not use the WCOMP interrupt. Use the WCOMP event.
35.3
Revision C
35.3.1 DSU
1 - If a debugger has issued a DSU Cold-Plugging procedure and then
released the CPU from the resulting ""CPU Reset Extension"", the CPU will
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be held in ""CPU Reset Extension"" after any upcoming reset event. Errata
reference: 12015
Fix/workaround:
The CPU must be released from the ""CPU Reset Extension"" either by writing a
one in the DSU STATUSA.CRSTEXT register or by applying an external reset
with SWCLK high or by power cycling the device.
35.3.2 NVMCTRL
1 - When the part is secured and EEPROM emulation area configured to
none, the CRC32 is not executed on the entire flash area but up to the onchip flash size minus half a row. Errata reference: 11988
Fix/Workaround:
When using CRC32 on a protected device with EEPROM emulation area
configured to none, compute the reference CRC32 value to the full chip flash size
minus half row.
35.3.3 VREG
1 - With default bit and register settings the device does not work as
specified in STANDBY mode if load current exceeds 100µA. Errata
reference: 11082
Fix/Workaround:
Set the FORCELDO bit in the VREG register.
35.3.4 Device
1 - When VDDIN is lower than the POR threshold during power rise or fall, an
internal pull-up resistor is enabled on pins with PTC functionality (see PORT
Function Multiplexing). Note that this behavior will be present even if PTC
functionality is not enabled on the pin. The POR level is defined in the
“Power-On Reset (POR) Characteristics” chapter. Errata reference: 10805
Fix/Workaround:
Use a pin without PTC functionality if the pull-up could damage your application
during power up.
2 - The values stored in the NVM software calibration area for the DFLL
calibration are not valid. Errata reference: 12843
Fix/Workaround:
None.
3 - In the table ""NVM User Row Mapping"", the WDT Window bitfield default
value on silicon is not as specified in the datasheet. The datasheet defines
the default value as 0x5, while it is 0xB on silicon. Errata reference: 13951
Fix/Workaround:
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None.
4 - Clock Failure detection for external OSC does not work in standby mode.
Errata reference: 12688
Fix/Workaround:
Before entering standby mode, move the CPU clock to an internal RC, disable
external OSC and disable the Clock Failure detector. Upon CPU wakeup, restart
external OSC (if it does not start, the failure occurred during standby), enable the
Clock Failure detector and move the CPU clock to the external OSC.
5 - If APB clock is stopped and GCLK clock is running, APB read access to
read-synchronized registers will freeze the system. The CPU and the DAP
AHB-AP are stalled, as a consequence debug operation is impossible.
Errata reference: 10416
Fix/Workaround:
Do not make read access to read-synchronized registers when APB clock is
stopped and GCLK is running. To recover from this situation, power cycle the
device or reset the device using the RESETN pin.
6 - The PORT output driver strength feature is not available. Errata
reference: 12684
Fix/Workaround:
None
7 - Maximum toggle frequency on all pins in worst case operating condition
is 8MHz. This affects all operations on the pins, including serial
communications. Errata reference: 10335
Fix/Workaround:
None.
8 - Do not enable Timers/Counters, AC (Analog Comparator), GCLK (Generic
Clock Controller), and SERCOM (I2C and SPI) to control Digital outputs in
standby sleep mode. Errata reference: 12786
Fix/Workaround:
Set the voltage regulator in Normal mode before entering STANDBY sleep mode.
This is done by setting the RUNSTDBY bit in the VREG register.
9 - After a clock failure detection (INTFLAG.CFD = 1), if INTFLAG.CFD is
cleared while the clock is still broken, the system is stuck. Errata reference:
12687
Fix/Workaround:
After a clock failure detection, do not clear INTFLAG.CFD or perform a system
reset.
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10 - In Standby, Idle1 and Idle2 sleep modes the device might not wake up
from sleep. An External Reset, Power on Reset or Watch Dog Reset will start
the device again. Errata reference: 13140
Fix/Workaround:
the SLEEPPRM bits in the NVMCTRL.CTRLB register must be written to 3
(NVMCTRL - CTRLB.bit.SLEEPPRM = 3) to ensure correct operation of the
device. The average power consumption of the device will increase with 20uA
compared to numbers in the electrical characteristics chapter.
11 - The temperature sensor is not accurate. No value is written into the
Temperature Log row during production test. Errata reference: 11731
Fix/Workaround:
None
12 - The DFLLVAL.COARSE, DFLLVAL.FINE, DFLLMUL.CSTEP and
DFLLMUL.FSTEP bit groups are not correctly located in the register map.
DFLLVAL.COARSE is only 5 bits and located in DFLLVAL[12..8].
DFLLVAL.FINE is only 8 bits and located in DFLLVAL[7:0]. DFLLMUL.CSTEP
is only 5 bits and located in DFLLMUL[28:24]. DFLLMUL.FSTEP is only 8 bits
and located in DFLLMUL[23:16] Errata reference: 10988
Fix/Workaround:
DFLLVAL.COARSE, DFLLVAL.FINE, DFLLMUL.CSTEP and DFLLMUL.FSTEP
should not be used if code compatibility is required with future device revisions.
13 - If the external XOSC32K is broken, neither the external pin RST nor the
GCLK software reset can reset the GCLK generators using XOSC32K as
source clock. Errata reference: 12164
Fix/Workaround:
Do a power cycle to reset the GCLK generators after an external XOSC32K
failure.
35.3.5 PM
1 - In debug mode, if a watchdog reset occurs, the debug session is lost.
Errata reference: 12196
Fix/Workaround:
A new debug session must be restart after a watchdog reset.
2 - The SysTick timer does not generate a wake up signal to the Power
Manager, and therefore cannot be used to wake up the CPU from sleep
mode. Errata reference: 11012
Fix/Workaround:
None.
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35.3.6 GCLK
1 - When the GCLK generator is enabled (GENCTRL.GENEN = 1), set as
output (GENCTRL.OE = 1) and use a division factor of one (GENDIV.DIV = 1
or 0 and GENCTRL.DIVSEL=0), the GCLK_IO might not be set to the
configured GENCTRL.OOV value after disabling the GCLK generator
(GENCTRL.GENEN=0). Errata reference: 10716
Fix/Workaround:
Disable the OE request of the GCLK generator (GENCTRL.OE = 0) before
disabling the GCLK generator (GENCTRL.GENEN = 0).
2 - The GCLK Generator clock is stuck when disabling the generator and
changing the division factor from one to a different value while the GCLK
generator is set as output. When the GCLK generator is enabled
(GENCTRL.GENEN=1), set as output (GENCTRL.OE=1) and use a division
factor of one (GENDIV.DIV=1 or 0 and GENCTRL.DIVSEL=0), if the division
factor is written to a value different of one or zero after disabling the GCLK
generator (GENCTRL.GENEN=0), the GCLK generator will be stuck. Errata
reference: 10686
Fix/Workaround:
Disable the OE request of the GCLK generator (GENCTRL.OE=0) before
disabling the GCLK generator (GENCTRL.GENEN=0).
3 - When a GCLK is locked and the generator used by the locked GCLK is
not GCLK generator 1, issuing a GCLK software reset will lock up the GCLK
with the SYNCBUSY flag always set. Errata reference: 10645
Fix/Workaround:
Do not issue a GCLK SWRST or map GCLK generator 1 to ""locked"" GCLKs.
35.3.7 XOSC32K
1 - The automatic amplitude control of the XOSC32K does not work. Errata
reference: 10933
Fix/Workaround:
Use the XOSC32K with Automatic Amplitude control disabled
(XOSC32K.AAMPEN = 0)
35.3.8 DFLL48M
1 - If the firmware writes to the DFLLMUL.MUL register in the same cycle as
the closed loop mode tries to update it, the fine calibration will first be reset
to midpoint and then incremented/decremented by the closed loop mode.
Then the coarse calibration will be performed with the updated fine value. If
this happens before the dfll have got a lock, the new fine calibration value
can be anything between 128-DFLLMUL.FSTEP and 128+DFLLMUL.FSTEP
which could give smaller calibration range for the fine calibration. Errata
reference: 10634
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Fix/Workaround:
Always wait until the DFLL48M has locked before writing the DFLLMUL.MUL
register
2 - The DFLL clock must be requested before being configured otherwise a
write access to a DFLL register can freeze the device. Errata reference: 9905
Fix/Workaround:
Write a zero to the DFLL ONDEMAND bit in the DFLLCTRL register before
configuring the DFLL module.
3 - Changing the DFLLVAL.FINE calibration bits of the DFLL48M Digital
Frequency Locked Loop might result in a short output frequency overshoot.
This might occur both in open loop mode while writing DFLLVAL.FINE by
software and closed loop mode when the DFLL automatically adjusts its
output frequency. Errata reference: 10537
Fix/Workaround:
- When using DFLL48M in open loop mode, be sure the DFLL48M is not used by
any module while DFLLVAL.FINE is written.
- When using DFLL48M in closed loop mode, be sure that DFLLCTRL.STABLE is
written to 1. The DFLL clock should not be used by any modules until the DFLL
locks are set.
If the application requires on-the-fly DFLL calibration (temperature/VCC drift
compensation), the firmware should perform, either periodically or when the
DFLL48M frequency differ too much from target frequency (indicated by
DFLLVAL.DIFF), the following:
o Switch system clock/module clocks to different clock than DFLL48M
o Re-initiate a DFLL48M closed loop lock sequence by disabling and re-enabling
the DFLL48M
o Wait for fine lock (PCLKSR.DFLLLCKF set to 1)
o Switch back system clock/module clocks to the DFLL48M
Better accuracy is achieved using a high multiplier for the DFLL48M, using a
scaled down or slow clock as reference. A multiplier of 6 will have a theoretical
worst case frequency deviation from the reference clock of +/- 8.33%. A multiplier
of 500 will have a theoretical worst case frequency deviation from the reference
clock of +/- 0.1%.
4 - If the DFLL48M reaches the maximum or minimum COARSE or FINE
calibration values during the locking sequence, an out of bounds interrupt
will be generated. These interrupts will be generated even if the final
calibration values at DFLL48M lock are not at maximum or minimum, and
might therefore be false out of bounds interrupts. Errata reference: 10669
Fix/Workaround:
Check that the lockbits: DFLLLCKC and DFLLLCKF in the SYSCTRL Interrupt
Flag Status and Clear register (INTFLAG) are both set before enabling the
DFLLOOB interrupt.
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35.3.9 BOD33
1 - The BOD33 HYST bit is not updated from NVM user row at power on. The
reset value of this bit is zero. Errata reference: 10565
Fix/Workaround:
None.
35.3.10 BOD12
1 - The BOD12 HYST bit is not updated from NVM user row at power on. The
reset value of this bit is zero. Errata reference: 10568
Fix/Workaround:
None.
35.3.11 EVSYS
1 - Using synchronous or resynchronized paths, some channels (0,3,6,7)
detect an overrun on every event even if no overrun condition is present.
Errata reference: 10895
Fix/Workaround:
- Ignore overrun detection bit for channels 0,3,6,7.
- Use channels 1,2,4,5 if overrun detection is required.
2 - Changing the selected generator of a channel can trigger a spurious
interrupt/event. Errata reference: 10443
Fix/Workaround:
To change the generator of a channel, first write with EDGESEL written to zero,
then perform a second write with EDGESEL written to its target value.
35.3.12 SERCOM
1 - The SERCOM SPI CTRLA register bit 17 (DOPO Bit 1) will always be zero,
and cannot be changed. Therefore the SERCOM SPI cannot be switched
between master and slave mode on the same DI and DO pins. Errata
reference: 10812
Fix/Workaround:
Connect the alternate DI and DO pins externally and use the port MUX to switch
between pin configurations for master and slave functionality.
2 - When the SERCOM is in slave SPI mode, the BUFOVF flag is not
automatically cleared when CTRLB.RXEN is set to zero. Errata reference:
10563
Fix/Workaround:
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The BUFOVF flag must be manually cleared by software.
3 - In TWI master mode, an ongoing transaction should be stalled
immediately when DBGCTRL.DBGSTOP is set and the CPU enters debug
mode. Instead, it is stopped when the current byte transaction is completed
and the corresponding interrupt is triggered if enabled. Errata reference:
12499
Fix/Workaround:
In TWI master mode, keep DBGCTRL.DBGSTOP=0 when in debug mode.
4 - The SERCOM SPI BUFOVF status bit is not set until the next character is
received after a buffer overflow, instead of directly after the overflow has
occurred. Furthermore the CTRLA.IBON bit will always be zero and cannot
be changed. Errata reference: 10551
Fix/Workaround:
None.
35.3.13 TC
1 - Spurious TC overflow and Match/Capture events may occur. Errata
reference: 13268
Fix/Workaround:
Do not use the TC overflow and Match/Capture events. Use the corresponding
Interrupts instead.
35.3.14 ADC
1 - When the ADC bus clock frequency(CLK_ADC_APB) is smaller than the
ADC asynchronous clock frequency(GCLK_ADC), issuing an ADC SWRST
(ADC.CTRLA.SWRST) will lock up the ADC with the SYNCBUSY
(ADC.STATUS.SYNCBUSY) flag always set. Errata reference: 10987
Fix/Workaround:
Do not issue an ADC SWRST if the ADC bus clock frequency (CLK_ADC_APB) is
smaller than the ADC asynchronous clock frequency(GCLK_ADC).
2 - The automatic right shift of the result when accumulating/averaging ADC
samples does not work. Errata reference: 10530
Fix/Workaround:
To accumulate or average more than 16 samples, one must add the number of
automatic right shifts to AVGCTRL.ADJRES to perform the correct number of
right shifts. For example, for averaging 128 samples, AVGCTRL.ADJRES must
be written to 7 instead of 4, as the automatic right shift of 3 is not done. For
oversampling to 16 bits resolution, AVGCTRL.ADJRES must be written to 4
instead of 0 as the automatic right shift of 4 is not done.
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The maximum number of right shifts that can be done using ADJRES is 7. This
means that when averaging more than 128 samples, the result will be more than
12 bits, and the additional right shifts to get the result down to 12 bits must be
done by firmware.
35.3.15 PTC
1 - WCOMP interrupt flag is not stable. The WCOMP interrupt flag will not
always be set as described in the datasheet. Errata reference: 12860
Fix/Workaround:
Do not use the WCOMP interrupt. Use the WCOMP event.
35.3.16 Flash
1 - When cache read mode is set to deterministic (READMODE=2), setting
CACHEDIS=1 does not lead to 0 wait states on Flash access. Errata
reference: 10830
Fix/Workaround:
When disabling the cache (CTRLB.CACHEDIS=1), the user must also set
READMODE to 0 (CTRLB.READMODE=0).
2 - When NVMCTRL issues either erase or write commands and the
NVMCTRL cache is not in LOW_POWER mode, CPU hardfault exception
may occur. Errata reference: 10804
Fix/Workaround:
Either:
- turn off cache before issuing flash commands by setting the NVMCTRL
CTRLB.CACHEDIS bit to one.
- Configure the cache in LOW_POWER mode by writing 0x1 into the NVMCTRL
CTRLB.READMODE bits.
35.4
Revision B
35.4.1 DSU
1 - If a debugger has issued a DSU Cold-Plugging procedure and then
released the CPU from the resulting ""CPU Reset Extension"", the CPU will
be held in ""CPU Reset Extension"" after any upcoming reset event. Errata
reference: 12015
Fix/workaround:
The CPU must be released from the ""CPU Reset Extension"" either by writing a
one in the DSU STATUSA.CRSTEXT register or by applying an external reset
with SWCLK high or by power cycling the device.
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35.4.2 NVMCTRL
1 - When the part is secured and EEPROM emulation area configured to
none, the CRC32 is not executed on the entire flash area but up to the onchip flash size minus half a row. Errata reference: 11988
Fix/Workaround:
When using CRC32 on a protected device with EEPROM emulation area
configured to none, compute the reference CRC32 value to the full chip flash size
minus half row.
35.4.3 VREG
1 - With default bit and register settings the device does not work as
specified in STANDBY mode if load current exceeds 100µA. Errata
reference: 11082
Fix/Workaround:
Set the FORCELDO bit in the VREG register.
35.4.4 Device
1 - When VDDIN is lower than the POR threshold during power rise or fall, an
internal pull-up resistor is enabled on pins with PTC functionality (see PORT
Function Multiplexing). Note that this behavior will be present even if PTC
functionality is not enabled on the pin. The POR level is defined in the
“Power-On Reset (POR) Characteristics” chapter. Errata reference: 10805
Fix/Workaround:
Use a pin without PTC functionality if the pull-up could damage your application
during power up.
2 - The values stored in the NVM software calibration area for the DFLL
calibration are not valid. Errata reference: 12843
Fix/Workaround:
None.
3 - In the table ""NVM User Row Mapping"", the WDT Window bitfield default
value on silicon is not as specified in the datasheet. The datasheet defines
the default value as 0x5, while it is 0xB on silicon. Errata reference: 13951
Fix/Workaround:
None.
4 - Clock Failure detection for external OSC does not work in standby mode.
Errata reference: 12688
Fix/Workaround:
Before entering standby mode, move the CPU clock to an internal RC, disable
external OSC and disable the Clock Failure detector. Upon CPU wakeup, restart
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external OSC (if it does not start, the failure occurred during standby), enable the
Clock Failure detector and move the CPU clock to the external OSC.
5 - If APB clock is stopped and GCLK clock is running, APB read access to
read-synchronized registers will freeze the system. The CPU and the DAP
AHB-AP are stalled, as a consequence debug operation is impossible.
Errata reference: 10416
Fix/Workaround:
Do not make read access to read-synchronized registers when APB clock is
stopped and GCLK is running. To recover from this situation, power cycle the
device or reset the device using the RESETN pin.
6 - The PORT output driver strength feature is not available. Errata
reference: 12684
Fix/Workaround:
None
7 - Maximum toggle frequency on all pins in worst case operating condition
is 8MHz. This affects all operations on the pins, including serial
communications. Errata reference: 10335
Fix/Workaround:
None.
8 - Do not enable Timers/Counters, AC (Analog Comparator), GCLK (Generic
Clock Controller), and SERCOM (I2C and SPI) to control Digital outputs in
standby sleep mode. Errata reference: 12786
Fix/Workaround:
Set the voltage regulator in Normal mode before entering STANDBY sleep mode.
This is done by setting the RUNSTDBY bit in the VREG register.
9 - After a clock failure detection (INTFLAG.CFD = 1), if INTFLAG.CFD is
cleared while the clock is still broken, the system is stuck. Errata reference:
12687
Fix/Workaround:
After a clock failure detection, do not clear INTFLAG.CFD or perform a system
reset.
10 - In Standby, Idle1 and Idle2 sleep modes the device might not wake up
from sleep. An External Reset, Power on Reset or Watch Dog Reset will start
the device again. Errata reference: 13140
Fix/Workaround:
the SLEEPPRM bits in the NVMCTRL.CTRLB register must be written to 3
(NVMCTRL - CTRLB.bit.SLEEPPRM = 3) to ensure correct operation of the
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device. The average power consumption of the device will increase with 20uA
compared to numbers in the electrical characteristics chapter.
11 - The temperature sensor is not accurate. No value is written into the
Temperature Log row during production test. Errata reference: 11731
Fix/Workaround:
None
12 - The DFLLVAL.COARSE, DFLLVAL.FINE, DFLLMUL.CSTEP and
DFLLMUL.FSTEP bit groups are not correctly located in the register map.
DFLLVAL.COARSE is only 5 bits and located in DFLLVAL[12..8].
DFLLVAL.FINE is only 8 bits and located in DFLLVAL[7:0]. DFLLMUL.CSTEP
is only 5 bits and located in DFLLMUL[28:24]. DFLLMUL.FSTEP is only 8 bits
and located in DFLLMUL[23:16] Errata reference: 10988
Fix/Workaround:
DFLLVAL.COARSE, DFLLVAL.FINE, DFLLMUL.CSTEP and DFLLMUL.FSTEP
should not be used if code compatibility is required with future device revisions.
13 - If the external XOSC32K is broken, neither the external pin RST nor the
GCLK software reset can reset the GCLK generators using XOSC32K as
source clock. Errata reference: 12164
Fix/Workaround:
Do a power cycle to reset the GCLK generators after an external XOSC32K
failure.
35.4.5 PM
1 - In debug mode, if a watchdog reset occurs, the debug session is lost.
Errata reference: 12196
Fix/Workaround:
A new debug session must be restart after a watchdog reset.
2 - The SysTick timer does not generate a wake up signal to the Power
Manager, and therefore cannot be used to wake up the CPU from sleep
mode. Errata reference: 11012
Fix/Workaround:
None.
35.4.6 GCLK
1 - When the GCLK generator is enabled (GENCTRL.GENEN = 1), set as
output (GENCTRL.OE = 1) and use a division factor of one (GENDIV.DIV = 1
or 0 and GENCTRL.DIVSEL=0), the GCLK_IO might not be set to the
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configured GENCTRL.OOV value after disabling the GCLK generator
(GENCTRL.GENEN=0). Errata reference: 10716
Fix/Workaround:
Disable the OE request of the GCLK generator (GENCTRL.OE = 0) before
disabling the GCLK generator (GENCTRL.GENEN = 0).
2 - The GCLK Generator clock is stuck when disabling the generator and
changing the division factor from one to a different value while the GCLK
generator is set as output. When the GCLK generator is enabled
(GENCTRL.GENEN=1), set as output (GENCTRL.OE=1) and use a division
factor of one (GENDIV.DIV=1 or 0 and GENCTRL.DIVSEL=0), if the division
factor is written to a value different of one or zero after disabling the GCLK
generator (GENCTRL.GENEN=0), the GCLK generator will be stuck. Errata
reference: 10686
Fix/Workaround:
Disable the OE request of the GCLK generator (GENCTRL.OE=0) before
disabling the GCLK generator (GENCTRL.GENEN=0).
3 - When a GCLK is locked and the generator used by the locked GCLK is
not GCLK generator 1, issuing a GCLK software reset will lock up the GCLK
with the SYNCBUSY flag always set. Errata reference: 10645
Fix/Workaround:
Do not issue a GCLK SWRST or map GCLK generator 1 to ""locked"" GCLKs.
35.4.7 XOSC32K
1 - The automatic amplitude control of the XOSC32K does not work. Errata
reference: 10933
Fix/Workaround:
Use the XOSC32K with Automatic Amplitude control disabled
(XOSC32K.AAMPEN = 0)
35.4.8 DFLL48M
1 - If the firmware writes to the DFLLMUL.MUL register in the same cycle as
the closed loop mode tries to update it, the fine calibration will first be reset
to midpoint and then incremented/decremented by the closed loop mode.
Then the coarse calibration will be performed with the updated fine value. If
this happens before the dfll have got a lock, the new fine calibration value
can be anything between 128-DFLLMUL.FSTEP and 128+DFLLMUL.FSTEP
which could give smaller calibration range for the fine calibration. Errata
reference: 10634
Fix/Workaround:
Always wait until the DFLL48M has locked before writing the DFLLMUL.MUL
register
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2 - The DFLL clock must be requested before being configured otherwise a write access to a
DFLL register can freeze the device. Errata reference: 9905
Fix/Workaround:
Write a zero to the DFLL ONDEMAND bit in the DFLLCTRL register before configuring the DFLL
module.
3 - Changing the DFLLVAL.FINE calibration bits of the DFLL48M Digital Frequency Locked
Loop might result in a short output frequency overshoot. This might occur both in open
loop mode while writing DFLLVAL.FINE by software and closed loop mode when the DFLL
automatically adjusts its output frequency. Errata reference: 10537
Fix/Workaround:
- When using DFLL48M in open loop mode, be sure the DFLL48M is not used by any module while
DFLLVAL.FINE is written.
- When using DFLL48M in closed loop mode, be sure that DFLLCTRL.STABLE is written to 1. The
DFLL clock should not be used by any modules until the DFLL locks are set.
If the application requires on-the-fly DFLL calibration (temperature/VCC drift compensation), the
firmware should perform, either periodically or when the DFLL48M frequency differ too much from
target frequency (indicated by DFLLVAL.DIFF), the following:
o Switch system clock/module clocks to different clock than DFLL48M
o Re-initiate a DFLL48M closed loop lock sequence by disabling and re-enabling the DFLL48M
o Wait for fine lock (PCLKSR.DFLLLCKF set to 1)
o Switch back system clock/module clocks to the DFLL48M
Better accuracy is achieved using a high multiplier for the DFLL48M, using a scaled down or slow
clock as reference. A multiplier of 6 will have a theoretical worst case frequency deviation from the
reference clock of +/- 8.33%. A multiplier of 500 will have a theoretical worst case frequency
deviation from the reference clock of +/- 0.1%.
4 - If the DFLL48M reaches the maximum or minimum COARSE or FINE calibration values
during the locking sequence, an out of bounds interrupt will be generated. These interrupts
will be generated even if the final calibration values at DFLL48M lock are not at maximum or
minimum, and might therefore be false out of bounds interrupts. Errata reference: 10669
Fix/Workaround:
Check that the lockbits: DFLLLCKC and DFLLLCKF in the SYSCTRL Interrupt Flag Status and
Clear register (INTFLAG) are both set before enabling the DFLLOOB interrupt.
35.4.9 BOD33
1 - The BOD33 HYST bit is not updated from NVM user row at power on. The reset value of
this bit is zero. Errata reference: 10565
Fix/Workaround:
None.
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35.4.10 BOD12
1 - The BOD12 HYST bit is not updated from NVM user row at power on. The reset value of
this bit is zero. Errata reference: 10568
Fix/Workaround:
None.
35.4.11 EVSYS
1 - Using synchronous or resynchronized paths, some channels (0,3,6,7) detect an overrun
on every event even if no overrun condition is present. Errata reference: 10895
Fix/Workaround:
- Ignore overrun detection bit for channels 0,3,6,7.
- Use channels 1,2,4,5 if overrun detection is required.
2 - Changing the selected generator of a channel can trigger a spurious interrupt/event.
Errata reference: 10443
Fix/Workaround:
To change the generator of a channel, first write with EDGESEL written to zero, then perform a
second write with EDGESEL written to its target value.
35.4.12 SERCOM
1 - The SERCOM SPI CTRLA register bit 17 (DOPO Bit 1) will always be zero, and cannot be
changed. Therefore the SERCOM SPI cannot be switched between master and slave mode
on the same DI and DO pins. Errata reference: 10812
Fix/Workaround:
Connect the alternate DI and DO pins externally and use the port MUX to switch between pin
configurations for master and slave functionality.
2 - When the SERCOM is in slave SPI mode, the BUFOVF flag is not automatically cleared
when CTRLB.RXEN is set to zero. Errata reference: 10563
Fix/Workaround:
The BUFOVF flag must be manually cleared by software.
3 - In TWI master mode, an ongoing transaction should be stalled immediately when
DBGCTRL.DBGSTOP is set and the CPU enters debug mode. Instead, it is stopped when the
current byte transaction is completed and the corresponding interrupt is triggered if
enabled. Errata reference: 12499
Fix/Workaround:
In TWI master mode, keep DBGCTRL.DBGSTOP=0 when in debug mode.
4 - The SERCOM SPI BUFOVF status bit is not set until the next character is received after a
buffer overflow, instead of directly after the overflow has occurred. Furthermore the
CTRLA.IBON bit will always be zero and cannot be changed. Errata reference: 10551
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Fix/Workaround:
None.
35.4.13 TC
1 - Spurious TC overflow and Match/Capture events may occur. Errata reference: 13268
Fix/Workaround:
Do not use the TC overflow and Match/Capture events. Use the corresponding Interrupts instead.
35.4.14 ADC
1 - When the ADC bus clock frequency(CLK_ADC_APB) is smaller than the ADC
asynchronous clock frequency(GCLK_ADC), issuing an ADC SWRST (ADC.CTRLA.SWRST)
will lock up the ADC with the SYNCBUSY (ADC.STATUS.SYNCBUSY) flag always set. Errata
reference: 10987
Fix/Workaround:
Do not issue an ADC SWRST if the ADC bus clock frequency (CLK_ADC_APB) is smaller than the
ADC asynchronous clock frequency(GCLK_ADC).
2 - The automatic right shift of the result when accumulating/averaging ADC samples does
not work. Errata reference: 10530
Fix/Workaround:
To accumulate or average more than 16 samples, one must add the number of automatic right
shifts to AVGCTRL.ADJRES to perform the correct number of right shifts. For example, for
averaging 128 samples, AVGCTRL.ADJRES must be written to 7 instead of 4, as the automatic
right shift of 3 is not done. For oversampling to 16 bits resolution, AVGCTRL.ADJRES must be
written to 4 instead of 0 as the automatic right shift of 4 is not done.
The maximum number of right shifts that can be done using ADJRES is 7. This means that when
averaging more than 128 samples, the result will be more than 12 bits, and the additional right
shifts to get the result down to 12 bits must be done by firmware.
35.4.15 PTC
1 - Some gain settings for the PTC in self-capacitance mode do not work. The two lowest
gain settings are not selectable and an attempt by the QTouch Library to set enable of these
may result in a higher sensitivity than optimal for the sensor. The PTC will not detect all
touches. This errata does not affect mutual-capacitance mode which operates as specified.
Errata reference: 10684
Fix/Workaround:
Use SAM D20 revision C or later for self-capacitance touch sensing.
2 - WCOMP interrupt flag is not stable. The WCOMP interrupt flag will not always be set as
described in the datasheet. Errata reference: 12860
Fix/Workaround:
Do not use the WCOMP interrupt. Use the WCOMP event.
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35.4.16 Flash
1 - When cache read mode is set to deterministic (READMODE=2), setting CACHEDIS=1
does not lead to 0 wait states on Flash access. Errata reference: 10830
Fix/Workaround:
When disabling the cache (CTRLB.CACHEDIS=1), the user must also set READMODE to 0
(CTRLB.READMODE=0).
2 - When NVMCTRL issues either erase or write commands and the NVMCTRL cache is not
in LOW_POWER mode, CPU hardfault exception may occur. Errata reference: 10804
Fix/Workaround:
Either:
- turn off cache before issuing flash commands by setting the NVMCTRL CTRLB.CACHEDIS bit to
one.
- Configure the cache in LOW_POWER mode by writing 0x1 into the NVMCTRL
CTRLB.READMODE bits.
35.5
Revision A
Not Sampled
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36.
Datasheet Revision History
Please note that the referring page numbers in this section are referred to this document. The referring revision in this
section are referring to the document revision.
36.1
Rev. N - 01/2015
z
Electrical
Characteristics
Updated Table 32-19 in the “Analog-to-Digital (ADC) Characteristics” on page 585
z
added two rows. One for Internal ratiometric reference 0 error and the other for
Internal ratiometric reference 1 error
z
added more details in Conditions of VREFINTVCC0 and VREFINTVCC1
z
Added Errata revision E
z
Updated Errata revision D:
Errata
z
z
z
Added new Errata references: 12290; 13950 and 13951
z
Updated Errata reference 13574: The software workaround: In I2C Slave mode,
writing the CTRLB register when in the AMATCH or DRDY interrupt service
routines can cause the state machine to reset
z
Updated Errata reference 13276 Workaround 2: At 105°C, use the ADC in single
shot mode only with VDDANA > 2.7V
Updated Errata revision C:
z
Added new Errrata reference:13951
z
Updated Errata reference 10537
Updated Errata revision B:
z
z
Added “Electrical Characteristics at 105°C” on page 674
Signal Description
List
z
VREFP renamed VREFA and VREFB in Table 6-1
Memories
z
Added a table note to the Table 9-4
z
Updated Table 12-7
z
Updated ADDR
Appendix
36.2
Added new Errrata reference:13951
Rev. M - 12/2014
DSU - Device
Service Unit
z
z
ADC - Analog-toDigital Converter
Added the description of “Bits 1:0 – AMOD[1:0]”
z
Removed all references to 1Khz from “32kHz External Crystal Oscillator (XOSC32K)
Operation” on page 139, “32kHz Internal Oscillator (OSC32K) Operation” on page 139
and “32kHz Ultra Low Power Internal Oscillator (OSCULP32K) Operation” on page 140
z
Changed EN1K bits to “Reserved” in XOSC32K and in OSC32K
z
Updated “I/O Pin Configuration” on page 292
System Controller
PORT
Added bit AMOD[1:0]
z
z
Removed reference to “open-drain”
Replaced AREFA/AREFB by VREFA/VREFB in “Analog Connections” on page 483
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DAC - Digital -toAnalog Converter
z
Replaced VREFP by VREFA in “Conversion Range” on page 552 and in Table 30-1
z
“Brown-Out Detectors Characteristics” on page 584:
z
Electrical
Characteristics
z
Added Figure 32-3, Figure 32-4 and clarifications.
z
Updated conditions in Table 32-17 and Table 32-18.
“Analog-to-Digital (ADC) Characteristics” on page 585:
z
z
z
Updated Table 32-39 in “Oscillators Characteristics” on page 596:
z
Renamed “Power consumption on VDDANA” to “Power consumption on VDDIN”
z
Added IDFLL specific typical value for revD and later
Updated Table 32-44 in “SERCOM in SPI Mode Timing” on page 605:
z
z
Package Information
Updated conditions in Table 32-22 and Table 32-23.
The value of tSCK“SCK period” updated from 42 to 84
Updated Table 33-1:
z
Added ThetaJA and ThetaJC values for the packages: 64-ball UFBGA and 45-ball
WLCSP
Schematic Checklist
z
Updated the introduction text “Schematic Checklist” on page 620
z
Replaced AREFA/AREFB by VREFA/VREFB in “Schematic Checklist” on page 620
z
Updated “Programming and Debug Ports” on page 627
z
Updated Errata revision D:
z
Errata
36.3
z
Updated all sub-sections, tables and figures
Added Errata reference 13574 related to CTRLB register / I2C in Slave Mode.
Rev. L - 09/2014
z
Added UFBGA64 and WLCSP45 packages
z
Introduced the 105°C devices
Pinout
z
Added two more pinouts: “UFBGA64” on page 12 and “WLCSP45” on page 14
Configuration
Summary
z
Updated “Configuration Summary” on page 3 to include UFBGA64 and WLCSP45
packages
z
Updated “Ordering Information” on page 4 to include UFBGA64, WLCSP45 packages
and the ordering codes for 105°C devices
Peripheral
Configuration
z
Updated “Peripherals Configuration Overview” on page 41
PM - Power
Management
z
Updated the table note 1 of the Table 15-3
z
Updated “Interrupts” on page 145
Features
Ordering Information
System Controller
z
z
Added one column “SleepWalking” in the Table 11-1
Interrupt source “BOD33DET - BOD33 Detection” is an Asynchronous interrupt
that can be used to wake-up the device from any sleep mode
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z
Updated “Always-On Mode” on page 189
z
Watchdog Timer
z
Updated “Interrupts” on page 189
z
z
External Interrupt
Controller
z
PORT
z
z
Instances “pad” changed to “pin”
z
Updated the sentence in “Basic Operation” on page 291
Updated “Interrupts” on page 318
Overrun Channel x (OVRx) and Event Detected Channel x (EVDx) are
asynchronous and can be used to wake-up the device from any sleep mode
z
Updated “Sleep Mode Operation” on page 319
z
Updated “Interrupts” on page 352
SERCOM USART
ADC - Analog-toDigital Converter
External interrupt pins (EXTINTx) and Non-maskable interrupt pin (NMI) are both
asynchronous and can be used to wake-up the device from any sleep mode
Updated “Basic Operation” on page 291
z
Event System
Overflow (INTFLAG.OVF), Compare n (INTFLAG.CMPn), Alarm 0
(INTFLAG.ALARMn) and Synchronization Ready (INTFLAG.SYNCRDY) are all
asynchronous and can be used to wake-up the device from any sleep mode
Updated “Interrupts” on page 250
z
z
Early Warning (EW) is an asynchronous interrupt that can be used to wake-up the
device from any sleep mode
Updated “Interrupts” on page 208
z
RTC
Added conditions for which CTRL.ALWAYSON bit must never be set to one by
software
z
RXS, RXC, TXC and DRE interrupts are asynchronous and can be used to wakeup the device from any sleep mode.
z
Fix a typo in the description of the bitfield MUXPOS of the register INPUTCTRL
z
Added more info to the table “Delay Gain” and about the propagation delay in subsection 7.3 “Prescaler”
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z
Updated “Maximum Clock Frequencies” on page 573
z
Added Table 32-6
z
Renamed Table 32-7 to "Maximum Peripheral Clock Frequencies" and updated
the whole table content including the symbols and descriptions
z
Added “Peripheral Power Consumption” on page 578
z
Updated “I/O Pin Characteristics” on page 580
z
Updated Table 32-11
z
z
Updated “SERCOM in SPI Mode Timing” on page 605
z
Electrical
Characteristics
Added typical tSCK in the Table 32-44
z
Updated “Voltage Regulator Characteristics” on page 583
z
Updated “Digital Frequency Locked Loop (DFLL48M) Characteristics” on page 598
z
z
Added a min value to the Cout parameter in Table 32-15
z
Renamed Table 32-39 to DFLL48M Characteristics - Closed Loop Mode
z
Updated the content and the table note of the Table 32-39
Updated the “Analog-to-Digital (ADC) Characteristics” on page 585
z
z
Table 32-19
z
Updated single-shot sample rate max value
z
Updated the table note 3
Table 32-20 and Table 32-21
z
z
Added definition of the gain accuracy parameter
Updated “Temperature Sensor Characteristics” on page 592
z
Table 32-29
z
Added temperature sensor accuracy and its condition
z
Added link for the values of XIN32/XOUT32 pins parasitic capacitance in Table 32-38
z
Added two more packages: “64-ball UFBGA” on page 613 and “45-ball WLCSP” on page
616
z
Updated errata for revision B, C and D. Added errata references: 10805, 12015, 12499,
13140, 13140 and 13268
Description
z
Updated partially the Atmel SAM D20 “Description” on page 1
Block Diagram
z
VREFP on DAC renamed VREFA
z
Updated Table
Schematic Checklist
Package Information
Errata
36.4
For tRISE and tFALL added different load conditions depending on DVRSTR
value
Rev. K – 05/2014
Memories
z
Changed the WDT window default value, WINDOW_1 to 0x5
z
Updated “DSU Chip Identification Method:” on page 49
z
Updated the protection state of the device in “ Starting CRC32 Calculation” on page 50
DSU - Device
Service Unit
z
“Family” renamed “Product family” and subfamily became “Product series”
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SYSCTRL - System
Controller
z
Updated “8MHz Internal Oscillator (OSC8M) Operation” on page 140
z
Updated Table 16-1
z
z
z
z
“External Multipurpose Crystal Oscillator (XOSC) Operation” on page 138
“32kHz External Crystal Oscillator (XOSC32K) Operation” on page 139
Added VREG register
z
Added VREG in “Register Summary” on page 147
z
Updated the description of Bit 6 – RUNSTDBY and Bit 13 – FORCELDO
z
Updated the description of “Interrupts” on page 145
z
Updated OSC8M
z
RTC - Real-Time
Counter
z
PORT
z
z
z
TOSC1 and TOSC2 renamed respectively XIN32 and XOUT32
Updated “Principle of Operation” on page 290
The reference for Pin Configuration registers changed to PINCFGy
Updated CTRLB
z
TC - Timer/Counter
Bits 11:0 - CALIB has two calibration fields CALIB[11-6] and CALIB[5:0]
Updated “Analog Connections” on page 204
z
SERCOM SPI
DFLL renamed DFLL48M
Added Note on how to enter standby mode in:
z
z
Updated the description of writing to FRANGE and CALIB
Bit 17 - RXEN is R/W
z
Updated Table 27-6
z
Updated CTRLC
z
Bits 1:0 - INVENx: Waveform Output x Invert Enable
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AC - Analog
Comparators
z
Added Bit 7 - LPMUX in CTRLA and updated “Register Summary” on page 533
DAC - Digital -toAnalog Converter
z
Added a new DAC Figure 30-1 with VREFP replaced by VREFA
z
Updated “Signal Description” on page 550
z
z
VREFP renamed VREFA
Updated Table 32-1
z
Updated IVDD and IGND max values
z
Added a detailed table note for IVDD and IGND
z
Added Table 32-2
z
Updated Table 32-3
z
z
Removed table note (1) related to the operating conditions
Updated the Table 32-8
z
Updated values in ACTIVE and IDLE0/1/2 modes
z
Updated the max values @ 85°C in STANDBY modes
z
Electrical
Characteristics
z
Max values updated to 100µA both for RT