ATMEL ATMEGA163 Nonvolatile program and data memory Datasheet

Features
• High-performance, Low-power AVR® 8-bit Microcontroller
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– 130 Powerful Instructions – Most Single Clock Cycle Execution
– 32 x 8 General Purpose Working Registers
– Fully Static Operation
– Up to 8 MIPS Throughput at 8 MHz
– On-chip 2-cycle Multiplier
Nonvolatile Program and Data Memories
Self-programming In-System Programmable Flash Memory
– 16K Bytes with Optional Boot Block (256 - 2K Bytes)
Endurance: 1,000 Write/Erase Cycles
– Boot Section Allows Reprogramming of Program Code without External
Programmer
– Optional Boot Code Section with Independent Lock Bits
– 512 Bytes EEPROM
Endurance: 100,000 Write/Erase Cycles
– 1024 Bytes Internal SRAM
– Programming Lock for Software Security
Peripheral Features
– Two 8-bit Timer/Counters with Separate Prescaler and Compare Mode
– One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and Capture
Mode
– Real Time Clock with Separate Oscillator and Counter Mode
– Three PWM Channels
– 8-channel, 10-bit ADC
– Byte-oriented Two-wire Serial Interface
– Programmable Serial UART
– Master/Slave SPI Serial Interface
– Programmable Watchdog Timer with Separate On-chip Oscillator
– Analog Comparator
Special Microcontroller Features
– Power-on Reset and Programmable Brown-out Detection
– Internal Calibrated RC Oscillator
– External and Internal Interrupt Sources
– Four Sleep Modes: Idle, ADC Noise Reduction, Power-save, and Power-down
Power Consumption at 4 MHz, 3.0V, 25°C
– Active 5.0 mA
– Idle Mode 1.9 mA
– Power-down Mode < 1 µA
I/O and Packages
– 32 Programmable I/O Lines
– 40-pin PDIP and 44-pin TQFP
Operating Voltages
– 2.7 - 5.5V for ATmega163L
– 4.0 - 5.5V for ATmega163
Speed Grades
– 0 - 4 MHz for ATmega163L
– 0 - 8 MHz for ATmega163
8-bit
Microcontroller
with 16K Bytes
In-System
Programmable
Flash
ATmega163
ATmega163L
Not Recommend for
New Designs. Use
ATmega16.
Rev. 1142E–AVR–02/03
1
(SCL)
(SDA)
Pin Configurations
(SDA)
(SCL)
2
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Description
The ATmega163 is a low-power CMOS 8-bit microcontroller based on the AVR architecture. By executing powerful instructions in a single clock cycle, the ATmega163
achieves throughputs approaching 1 MIPS per MHz allowing the system designer to
optimize power consumption versus processing speed.
Block Diagram
Figure 1. Block Diagram
PA0 - PA7
PC0 - PC7
PORTA DRIVERS
PORTC DRIVERS
VCC
GND
DATA DIR.
REG. PORTA
DATA REGISTER
PORTA
DATA REGISTER
PORTC
DATA DIR.
REG. PORTC
8-BIT DATA BUS
AVCC
ANALOG MUX
ADC
AGND
AREF
OSCILLATOR
2-WIRE SERIAL
INTERFACE
INTERNAL
REFERENCE
INTERNAL
OSCILLATOR
OSCILLATOR
TIMING AND
CONTROL
PROGRAM
COUNTER
STACK
POINTER
WATCHDOG
TIMER
PROGRAM
FLASH
SRAM
MCU CONTROL
REGISTER
INSTRUCTION
REGISTER
GENERAL
PURPOSE
REGISTERS
TIMER/
COUNTERS
X
Y
Z
INTERRUPT
UNIT
ALU
EEPROM
STATUS
REGISTER
INTERNAL
CALIBRATED
OSCILLATOR
SPI
UART
INSTRUCTION
DECODER
CONTROL
LINES
ANALOG
COMPARATOR
+
-
PROGRAMMING
LOGIC
DATA REGISTER
PORTB
DATA DIR.
REG. PORTB
XTAL1
DATA REGISTER
PORTD
XTAL2
RESET
DATA DIR.
REG. PORTD
PORTB DRIVERS
PORTD DRIVERS
PB0 - PB7
PD0 - PD7
The AVR core combines a rich instruction set with 32 general purpose working registers.
All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowing
two independent registers to be accessed in one single instruction executed in one clock
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1142E–AVR–02/03
cycle. The resulting architecture is more code efficient while achieving throughputs up to
ten times faster than conventional CISC microcontrollers.
The ATmega163 provides the following features: 16K bytes of In-System Self-Programmable Flash, 512 bytes EEPROM, 1024 bytes SRAM, 32 general purpose I/O lines, 32
general purpose working registers, three flexible Timer/Counters with compare modes,
internal and external interrupts, a byte oriented Two-wire Serial Interface, an 8-channel,
10-bit ADC, a programmable Watchdog Timer with internal Oscillator, a programmable
serial UART, an SPI serial port, and four software selectable power saving modes. The
Idle mode stops the CPU while allowing the SRAM, Timer/Counters, SPI port, and interrupt system to continue functioning. The Power-down mode saves the register contents
but freezes the Oscillator, disabling all other chip functions until the next interrupt or
Hardware Reset. In Power-save mode, the asynchronous Timer Oscillator continues to
run, allowing the user to maintain a timer base while the rest of the device is sleeping.
The ADC Noise Reduction mode stops the CPU and all I/O modules except asynchronous timer and ADC, to minimize switching noise during ADC conversions.
The On-chip ISP Flash can be programmed through an SPI serial interface or a conventional programmer. By installing a Self-Programming Boot Loader, the microcontroller
can be updated within the application without any external components. The Boot Program can use any interface to download the application program in the Application Flash
memory. By combining an 8-bit CPU with In-System Self-Programmable Flash on a
monolithic chip, the Atmel ATmega163 is a powerful microcontroller that provides a
highly flexible and cost effective solution to many embedded control applications.
The ATmega163 AVR is supported with a full suite of program and system development
tools including: C compilers, macro assemblers, program debugger/simulators, In-Circuit Emulators, and evaluation kits.
Pin Descriptions
VCC
Digital supply voltage.
GND
Digital ground.
Port A (PA7..PA0)
Port A serves as the analog inputs to the A/D Converter.
Port A also serves as an 8-bit bi-directional I/O port, if the A/D Converter is not used.
Port pins can provide internal pull-up resistors (selected for each bit). The Port A output
buffers can sink 20mA and can drive LED displays directly. When pins PA0 to PA7 are
used as inputs and are externally pulled low, they will source current if the internal pullup resistors are activated. The Port A pins are tristated when a reset condition becomes
active, even if the clock is not running.
Port B (PB7..PB0)
Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each
bit). The Port B output buffers can sink 20 mA. As inputs, Port B pins that are externally
pulled low will source current if the pull-up resistors are activated. Port B also serves the
functions of various special features of the ATmega83/163 as listed on page 117. The
Port B pins are tristated when a reset condition becomes active, even if the clock is not
running.
Port C (PC7..PC0)
Port C is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each
bit). The Port C output buffers can sink 20 mA. As inputs, Port C pins that are externally
pulled low will source current if the pull-up resistors are activated. The Port C pins are
tristated when a reset condition becomes active, even if the clock is not running.
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ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Port C also serves the functions of various special features of the ATmega163 as listed
on page 124.
Port D (PD7..PD0)
Port D is an 8-bit bidirectional I/O port with internal pull-up resistors (selected for each
bit). The Port D output buffers can sink 20 mA. As inputs, Port D pins that are externally
pulled low will source current if the pull-up resistors are activated. Port D also serves the
functions of various special features of the ATmega163 as listed on page 128. The Port
D pins are tristated when a reset condition becomes active, even if the clock is not
running.
RESET
Reset input. A low level on this pin for more than 500 ns will generate a Reset, even if
the clock is not running. Shorter pulses are not guaranteed to generate a Reset.
XTAL1
Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.
XTAL2
Output from the inverting Oscillator amplifier.
AVCC
This is the supply voltage pin for Port A and the A/D Converter. It should be externally
connected to VCC, even if the ADC is not used. If the ADC is used, it should be connected to VCC through a low-pass filter. See page 105 for details on operation of the
ADC.
AREF
AREF is the analog reference input pin for the A/D Converter. For ADC operations, a
voltage in the range 2.5V to AVCC can be applied to this pin.
AGND
Analog ground. If the board has a separate analog ground plane, this pin should be connected to this ground plane. Otherwise, connect to GND.
Clock Options
The device has the following clock source options, selectable by Flash Fuse bits as
shown:
Table 1. Device Clocking Options Select(1)
Device Clocking Option
CKSEL3..0
External Crystal/Ceramic Resonator
1111 - 1010
External Low-frequency Crystal
1001 - 1000
External RC Oscillator
0111 - 0101
Internal RC Oscillator
0100 - 0010
External Clock
0001 - 0000
Note:
1. “1” means unprogrammed, “0” means programmed.
The various choices for each clocking option give different start-up times as shown in
Table 5 on page 25.
Internal RC Oscillator
The internal RC Oscillator option is an On-chip Oscillator running at a fixed frequency of
nominally 1 MHz. If selected, the device can operate with no external components. The
device is shipped with this option selected. See “EEPROM Read/Write Access” on page
62 for information on calibrating this Oscillator.
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1142E–AVR–02/03
Crystal Oscillator
XTAL1 and XTAL2 are input and output, respectively, of an inverting amplifier which can
be configured for use as an On-chip Oscillator, as shown in Figure 2. Either a quartz
crystal or a ceramic resonator may be used.
Figure 2. Oscillator Connections
External Clock
To drive the device from an external clock source, XTAL1 should be driven as shown in
Figure 3.
Figure 3. External Clock Drive Configuration
External RC Oscillator
For timing insensitive applications, the external RC configuration shown in Figure 4 can
be used. For details on how to choose R and C, see Table 64 on page 162.
Figure 4. External RC Configuration
VCC
R
NC
XTAL2
XTAL1
C
GND
Timer Oscillator
6
For the Timer Oscillator pins, TOSC1 and TOSC2, the crystal is connected directly
between the pins. No external capacitors are needed. The Oscillator is optimized for use
with a 32,768 Hz watch crystal. Applying an external clock source to the TOSC1 pin is
not recommended.
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Architectural
Overview
The fast-access Register File concept contains 32 x 8-bit general purpose working registers with a single clock cycle access time. This means that during one single clock
cycle, one Arithmetic Logic Unit (ALU) operation is executed. Two operands are output
from the Register File, the operation is executed, and the result is stored back in the
Register File – in one clock cycle.
Six of the 32 registers can be used as three 16-bits indirect address register pointers for
Data Space addressing – enabling efficient address calculations. One of the three
address pointers is also used as the address pointer for look-up tables in Flash Program
memory. These added function registers are the 16-bits X-, Y-, and Z-register.
The ALU supports arithmetic and logic operations between registers or between a constant and a register. Single register operations are also executed in the ALU. Figure 5
shows the ATmega163 AVR Enhanced RISC microcontroller architecture.
In addition to the register operation, the conventional Memory Addressing modes can be
used on the Register File as well. This is enabled by the fact that the Register File is
assigned the 32 lowest Data Space addresses ($00 - $1F), allowing them to be
accessed as though they were ordinary memory locations.
The I/O Memory space contains 64 addresses for CPU peripheral functions as Control
Registers, Timer/Counters, A/D-converters, and other I/O functions. The I/O Memory
can be accessed directly, or as the Data Space locations following those of the Register
File, $20 - $5F.
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1142E–AVR–02/03
Figure 5. The ATmega163 AVR RISC Architecture
Data Bus 8-bit
Interrupt
Unit
8K X 16
Program
Memory
Program
Counter
Status
and Control
32 x 8
General
Purpose
Registrers
Instruction
Register
Serial
UART
Direct Addressing
Indirect Addressing
Two-wire Serial
Interface
Instruction
Decoder
Control Lines
SPI
Unit
ALU
8-bit
Timer/Counter
16-bit
Timer/Counter
with PWM
1024 x 8
Data
SRAM
8-bit
Timer/Counter
with PWM
Watchdog
Timer
512 x 8
EEPROM
A/D Converter
32
I/O Lines
Analog
Comparator
The AVR uses a Harvard architecture concept – with separate memories and buses for
program and data. The Program memory is executed with a two stage pipeline. While
one instruction is being executed, the next instruction is pre-fetched from the Program
memory. This concept enables instructions to be executed in every clock cycle. The
Program memory is In-System Re-programmable Flash memory.
With the jump and call instructions, the whole 8K word address space is directly
accessed. Most AVR instructions have a single 16-bit word format. Every program
memory address contains a 16- or 32-bit instruction.
Program Flash memory space is divided in two sections, the Boot Program section (256
to 2,048 bytes, see page 134) and the Application Program section. Both sections have
dedicated Lock bits for write and read/write protection. The SPM instruction that writes
into the Application Flash memory section is allowed only in the Boot Program section.
During interrupts and subroutine calls, the return address Program Counter (PC) is
stored on the Stack. The Stack is effectively allocated in the general data SRAM, and
consequently the Stack size is only limited by the total SRAM size and the usage of the
SRAM. All user programs must initialize the SP in the reset routine (before subroutines
or interrupts are executed). The 11-bit Stack Pointer SP is read/write accessible in the
I/O space.
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ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
The 1,024 bytes data SRAM can be easily accessed through the five different addressing modes supported in the AVR architecture.
The memory spaces in the AVR architecture are all linear and regular memory maps.
A flexible interrupt module has its Control Registers in the I/O space with an additional
Global Interrupt Enable bit in the Status Register. All interrupts have a separate Interrupt
Vector in the Interrupt Vector table at the beginning of the Program memory. The interrupts have priority in accordance with their Interrupt Vector position. The lower the
Interrupt Vector address, the higher the priority.
Figure 6. Memory Maps
Program Memory
$0000
Application Flash Section
Boot Flash Section
$1FFF
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1142E–AVR–02/03
The General Purpose
Register File
Figure 7 shows the structure of the 32 general purpose working registers in the CPU.
Figure 7. AVR CPU General Purpose Working Registers
7
0
Addr.
R0
$00
R1
$01
R2
$02
…
R13
$0D
General
R14
$0E
Purpose
R15
$0F
Working
R16
$10
Registers
R17
$11
…
R26
$1A
X-register Low Byte
R27
$1B
X-register High Byte
R28
$1C
Y-register Low Byte
R29
$1D
Y-register High Byte
R30
$1E
Z-register Low Byte
R31
$1F
Z-register High Byte
All the register operating instructions in the instruction set have direct and single cycle
access to all registers. The only exception is the five constant arithmetic and logic
instructions SBCI, SUBI, CPI, ANDI, and ORI between a constant and a register, and
the LDI instruction for load immediate constant data. These instructions apply to the
second half of the registers in the Register File – R16..R31. The general SBC, SUB, CP,
AND, and OR and all other operations between two registers or on a single register
apply to the entire Register File.
As shown in Figure 7, each register is also assigned a data memory address, mapping
them directly into the first 32 locations of the user Data Space. Although not being physically implemented as SRAM locations, this memory organization provides great
flexibility in access of the registers, as the X-, Y-, and Z-registers can be set to index any
register in the file.
The X-register, Y-register, and
Z-register
The registers R26..R31 have some added functions to their general purpose usage.
These registers are address pointers for indirect addressing of the Data Space. The
three indirect address registers X, Y, and Z are defined as:
Figure 8. The X-, Y-, and Z-registers
15
X - register
XH
7
XL
0
R27 ($1B)
15
Y - register
YH
7
15
7
R31 ($1F)
10
0
R26 ($1A)
YL
0
R29 ($1D)
Z - register
0
7
0
7
0
R28 ($1C)
ZH
ZL
0
7
0
0
R30 ($1E)
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
In the different addressing modes these address registers have functions as fixed displacement, automatic increment and decrement (see the descriptions for the different
instructions).
The ALU – Arithmetic
Logic Unit
The high-performance AVR ALU operates in direct connection with all the 32 general
purpose working registers. Within a single clock cycle, ALU operations between registers in the Register File are executed. The ALU operations are divided into three main
categories – arithmetic, logical, and bit-functions. ATmega163 also provides a powerful
multiplier supporting both signed/unsigned multiplication and fractional format. See the
Instruction Set section for a detailed description.
The In-System SelfProgrammable Flash
Program Memory
The ATmega163 contains 16K bytes On-chip In-System Self-Programmable Flash
memory for program storage. Since all instructions are 16- or 32-bit words, the Flash is
organized as 8K x 16. The Flash Program memory space is divided in two sections,
Boot Program section and Application Program section.
The Flash memory has an endurance of at least 1,000 write/erase cycles. The
ATmega163 Program Counter (PC) is 13 bits wide, thus addressing the 8,192 Program
Memory locations. The operation of Boot Program section and associated Boot Lock
bits for software protection are described in detail on page 134. See also page 154 for a
detailed description on Flash data serial downloading.
Constant tables can be allocated within the entire Program Memory address space (see
the LPM – Load Program Memory instruction description).
See also page 12 for the different Program Memory Addressing modes.
The SRAM Data Memory
Figure 9 shows how the ATmega163 SRAM Memory is organized.
Figure 9. SRAM Organization
Register File
Data Address Space
R0
R1
R2
...
$0000
$0001
$0002
...
R29
R30
R31
I/O Registers
$00
$01
$02
...
$001D
$001E
$001F
$3D
$3E
$3F
$005D
$005E
$005F
Internal SRAM
$0060
$0061
...
$0020
$0021
$0022
...
$045E
$045F
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The lower 1,120 Data Memory locations address the Register File, the I/O Memory, and
the internal data SRAM. The first 96 locations address the Register File + I/O Memory,
and the next 1,024 locations address the internal data SRAM.
The five different addressing modes for the data memory cover: Direct, Indirect with Displacement, Indirect, Indirect with Pre-decrement, and Indirect with Post-increment. In
the Register File, registers R26 to R31 feature the indirect Addressing Pointer
Registers.
The direct addressing reaches the entire data space.
The Indirect with Displacement mode features a 63 address locations reach from the
base address given by the Y- or Z-register.
When using register indirect addressing modes with automatic pre-decrement and postincrement, the address registers X, Y, and Z are decremented and incremented.
The 32 general purpose working registers, 64 I/O Registers, and the 1,024 bytes of
internal data SRAM in the ATmega163 are all accessible through all these addressing
modes.
The Program and Data
Addressing Modes
The ATmega163 AVR Enhanced RISC microcontroller supports powerful and efficient
addressing modes for access to the Program Memory (Flash) and Data Memory
(SRAM, Register File, and I/O Memory). This section describes the different addressing
modes supported by the AVR architecture. In the figures, OP means the operation code
part of the instruction word. To simplify, not all figures show the exact location of the
addressing bits.
Register Direct, Single
Register Rd
Figure 10. Direct Single Register Addressing
The operand is contained in register d (Rd).
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ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Register Direct, Two Registers
Rd And Rr
Figure 11. Direct Register Addressing, Two Registers
Operands are contained in register r (Rr) and d (Rd). The result is stored in register d
(Rd).
I/O Direct
Figure 12. I/O Direct Addressing
Operand address is contained in 6 bits of the instruction word. n is the destination or
source register address.
Data Direct
Figure 13. Direct Data Addressing
Data Space
20 19
31
OP
16
$0000
Rr/Rd
16 LSBs
15
0
$045F
A 16-bit Data Address is contained in the 16 LSBs of a two-word instruction. Rd/Rr
specify the destination or source register.
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1142E–AVR–02/03
Data Indirect with
Displacement
Figure 14. Data Indirect with Displacement
Data Space
$0000
15
0
Y OR Z - REGISTER
15
10
OP
6 5
n
0
a
$045F
Operand address is the result of the Y- or Z-register contents added to the address contained in 6 bits of the instruction word.
Data Indirect
Figure 15. Data Indirect Addressing
Data Space
$0000
15
0
X, Y OR Z - REGISTER
$045F
Operand address is the contents of the X-, Y-, or the Z-register.
Data Indirect with Predecrement
Figure 16. Data Indirect Addressing with Pre-decrement
Data Space
$0000
15
0
X, Y OR Z - REGISTER
-1
$045F
The X-, Y-, or the Z-register is decremented before the operation. Operand address is
the decremented contents of the X-, Y-, or the Z-register.
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ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Data Indirect with Postincrement
Figure 17. Data Indirect Addressing with Post-increment
Data Space
$0000
15
0
X, Y OR Z - REGISTER
1
$045F
The X-, Y-, or the Z-register is incremented after the operation. Operand address is the
content of the X-, Y-, or the Z-register prior to incrementing.
Constant Addressing Using
The LPM and SPM
Instructions
Figure 18. Code Memory Constant Addressing
$1FFF
Constant byte address is specified by the Z-register contents. The 15 MSBs select word
address (0 - 8K). For LPM, the LSB selects Low Byte if cleared (LSB = 0) or High Byte if
set (LSB = 1). For SPM, the LSB should be cleared.
Indirect Program Addressing,
IJMP and ICALL
Figure 19. Indirect Program Memory Addressing
$1FFF
Program execution continues at address contained by the Z-register (i.e., the PC is
loaded with the contents of the Z-register).
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Relative Program Addressing,
RJMP and RCALL
Figure 20. Relative Program Memory Addressing
1
$1FFF
Program execution continues at address PC + k + 1.
The relative address k is from -2,048 to 2,047.
The EEPROM Data
Memory
The ATmega163 contains 512 bytes of data EEPROM memory. It is organized as a separate data space, in which single bytes can be read and written. The EEPROM has an
endurance of at least 100,000 write/erase cycles. The access between the EEPROM
and the CPU is described on page 62 specifying the EEPROM Address Registers, the
EEPROM Data Register, and the EEPROM Control Register.
For the SPI data downloading, see page 154 for a detailed description.
Memory Access Times
and Instruction
Execution Timing
This section describes the general access timing concepts for instruction execution and
internal memory access.
The AVR CPU is driven by the System Clock Ø, directly generated from the main Oscillator for the chip. No internal clock division is used.
Figure 21 shows the parallel instruction fetches and instruction executions enabled by
the Harvard architecture and the fast-access Register File concept. This is the basic
pipelining concept to obtain up to 1 MIPS per MHz with the corresponding unique results
for functions per cost, functions per clocks, and functions per power-unit.
Figure 21. The Parallel Instruction Fetches and Instruction Executions
T1
T2
T3
T4
System Clock Ø
1st Instruction Fetch
1st Instruction Execute
2nd Instruction Fetch
2nd Instruction Execute
3rd Instruction Fetch
3rd Instruction Execute
4th Instruction Fetch
Figure 22 shows the internal timing concept for the Register File. In a single clock cycle
an ALU operation using two register operands is executed, and the result is stored back
to the destination register.
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ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Figure 22. Single Cycle ALU Operation
T1
T2
T3
T4
System Clock Ø
Total Execution Time
Register Operands Fetch
ALU Operation Execute
Result Write Back
The internal data SRAM access is performed in two System Clock cycles as described
in Figure 23.
Figure 23. On-chip Data SRAM Access Cycles
T1
T2
T3
T4
System Clock Ø
Address
Prev. Address
Address
Write
Data
WR
Read
Data
RD
I/O Memory
The I/O space definition of the ATmega163 is shown in the following table:
Table 2. ATmega163 I/O Space (1)
I/O Address
(SRAM Address)
Name
Function
$3F ($5F)
SREG
Status REGister
$3E ($5E)
SPH
Stack Pointer High
$3D ($5D)
SPL
Stack Pointer Low
$3B ($5B)
GIMSK
$3A ($5A)
GIFR
$39 ($59)
TIMSK
$38 ($58)
TIFR
$37 ($57)
SPMCR
SPM Control Register
$36 ($56)
TWCR
Two-wire Serial Interface Control Register
$35 ($55)
MCUCR
MCU general Control Register
$34 ($54)
MCUSR
MCU general Status Register
$33 ($53)
TCCR0
Timer/Counter0 Control Register
General Interrupt MaSK Register
General Interrupt Flag Register
Timer/Counter Interrupt MaSK Register
Timer/Counter Interrupt Flag Register
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Table 2. ATmega163 I/O Space (Continued) (1)
18
I/O Address
(SRAM Address)
Name
Function
$32 ($52)
TCNT0
Timer/Counter0 (8-bit)
$31 ($51)
OSCCAL
Oscillator Calibration Register
$30 ($50)
SFIOR
Special Function I/O Register
$2F ($4F)
TCCR1A
Timer/Counter1 Control Register A
$2E ($4E)
TCCR1B
Timer/Counter1 Control Register B
$2D ($4D)
TCNT1H
Timer/Counter1 High-byte
$2C ($4C)
TCNT1L
Timer/Counter1 Low-byte
$2B ($4B)
OCR1AH
Timer/Counter1 Output Compare Register A High-byte
$2A ($4A)
OCR1AL
Timer/Counter1 Output Compare Register A Low-byte
$29 ($49)
OCR1BH
Timer/Counter1 Output Compare Register B High-byte
$28 ($48)
OCR1BL
Timer/Counter1 Output Compare Register B Low-byte
$27 ($47)
ICR1H
T/C 1 Input Capture Register High-byte
$26 ($46)
ICR1L
T/C 1 Input Capture Register Low-byte
$25 ($45)
TCCR2
Timer/Counter2 Control Register
$24 ($44)
TCNT2
Timer/Counter2 (8-bit)
$23 ($43)
OCR2
Timer/Counter2 Output Compare Register
$22 ($42)
ASSR
Asynchronous Mode Status Register
$21 ($41)
WDTCR
Watchdog Timer Control Register
$20 ($40)
UBRRHI
UART Baud Rate Register High-byte
$1F ($3F)
EEARH
EEPROM Address Register High-byte
$1E ($3E)
EEARL
EEPROM Address Register Low-byte
$1D ($3D)
EEDR
EEPROM Data Register
$1C ($3C)
EECR
EEPROM Control Register
$1B ($3B)
PORTA
$1A ($3A)
DDRA
Data Direction Register, Port A
$19 ($39)
PINA
Input Pins, Port A
$18 ($38)
PORTB
$17 ($37)
DDRB
Data Direction Register, Port B
$16 ($36)
PINB
Input Pins, Port B
$15 ($35)
PORTC
$14 ($34)
DDRC
Data Direction Register, Port C
$13 ($33)
PINC
Input Pins, Port C
$12 ($32)
PORTD
$11 ($31)
DDRD
Data Direction Register, Port D
$10 ($30)
PIND
Input Pins, Port D
Data Register, Port A
Data Register, Port B
Data Register, Port C
Data Register, Port D
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Table 2. ATmega163 I/O Space (Continued) (1)
I/O Address
(SRAM Address)
Name
Function
$0F ($2F)
SPDR
SPI I/O Data Register
$0E ($2E)
SPSR
SPI Status Register
$0D ($2D)
SPCR
SPI Control Register
$0C ($2C)
UDR
UART I/O Data Register
$0B ($2B)
UCSRA
UART Control and Status Register A
$0A ($2A)
UCSRB
UART Control and Status Register B
$09 ($29)
UBRR
UART Baud Rate Register
$08 ($28)
ACSR
Analog Comparator Control and Status Register
$07 ($27)
ADMUX
ADC Multiplexer Select Register
$06 ($26)
ADCSR
ADC Control and Status Register
$05 ($25)
ADCH
ADC Data Register High
$04 ($24)
ADCL
ADC Data Register Low
$03 ($23)
TWDR
Two-wire Serial Interface Data Register
$02 ($22)
TWAR
Two-wire Serial Interface (Slave) Address Register
$01 ($21)
TWSR
Two-wire Serial Interface Status Register
$00 ($20)
TWBR
Two-wire Serial Interface Bit Rate Register
Note:
1. Reserved and unused locations are not shown in the table.
All ATmega163 I/Os and peripherals are placed in the I/O space. The I/O locations are
accessed by the IN and OUT instructions, transferring data between the 32 general purpose working registers and the I/O space. I/O Registers within the address range $00 $1F are directly bit-accessible using the SBI and CBI instructions. In these registers,
the value of single bits can be checked by using the SBIS and SBIC instructions. Refer
to the instruction set chapter for more details. When using the I/O specific commands IN
and OUT, the I/O addresses $00 - $3F must be used. When addressing I/O Registers as
SRAM, $20 must be added to these addresses. All I/O Register addresses throughout
this document are shown with the SRAM address in parentheses.
For compatibility with future devices, reserved bits should be written to zero if accessed.
Reserved I/O memory addresses should never be written.
Some of the Status Flags are cleared by writing a logical one to them. Note that the CBI
and SBI instructions will operate on all bits in the I/O Register, writing a one back into
any Flag read as set, thus clearing the Flag. The CBI and SBI instructions work with registers $00 to $1F only.
The I/O and Peripherals Control Registers are explained in the following sections.
19
1142E–AVR–02/03
The Status Register – SREG
The AVR Status Register – SREG – at I/O space location $3F ($5F) is defined as:
Bit
7
6
5
4
3
2
1
0
$3F ($5F)
I
T
H
S
V
N
Z
C
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
SREG
• Bit 7 – I: Global Interrupt Enable
The Global Interrupt Enable bit must be set (one) for the interrupts to be enabled. The
individual interrupt enable control is then performed in the Interrupt Mask Registers. If
the Global Interrupt Enable Register is cleared (zero), none of the interrupts are enabled
independent of the values of the Interrupt Mask Registers. The I-bit is cleared by hardware after an interrupt has occurred, and is set by the RETI instruction to enable
subsequent interrupts.
• Bit 6 – T: Bit Copy Storage
The Bit Copy instructions BLD (Bit LoaD) and BST (Bit STore) use the T-bit as source
and destination for the operated bit. A bit from a register in the Register File can be copied into T by the BST instruction, and a bit in T can be copied into a bit in a register in the
Register File by the BLD instruction.
• Bit 5 – H: Half Carry Flag
The Half Carry Flag H indicates a half carry in some arithmetic operations. See the
Instruction Set Description for detailed information.
• Bit 4 – S: Sign Bit, S = N ⊕ V
The S-bit is always an exclusive or between the Negative Flag N and the Two’s Complement Overflow Flag V. See the Instruction Set Description for detailed information.
• Bit 3 – V: Two’s Complement Overflow Flag
The Two’s Complement Overflow Flag V supports two’s complement arithmetics. See
the Instruction Set Description for detailed information.
• Bit 2 – N: Negative Flag
The Negative Flag N indicates a negative result in an arithmetic or logic operation. See
the Instruction Set Description for detailed information.
• Bit 1 – Z: Zero Flag
The Zero Flag Z indicates a zero result in an arithmetic or logic operation. See the
Instruction Set Description for detailed information.
• Bit 0 – C: Carry Flag
The Carry Flag C indicates a carry in an arithmetic or logic operation. See the Instruction
Set Description for detailed information.
Note that the Status Register is not automatically stored when entering an interrupt routine and restored when returning from an interrupt routine. This must be handled by
software.
20
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
The Stack Pointer – SP
The ATmega163 Stack Pointer is implemented as two 8-bit registers in the I/O space
locations $3E ($5E) and $3D ($5D). As the ATmega163 data memory has $460 locations, 11 bits are used.
Bit
15
14
13
12
11
10
9
8
$3E ($5E)
–
–
–
–
–
SP10
SP9
SP8
SPH
$3D ($5D)
SP7
SP6
SP5
SP4
SP3
SP2
SP1
SP0
SPL
7
6
5
4
3
2
1
0
Read/Write
Initial Value
R
R
R
R
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
The Stack Pointer points to the data SRAM Stack area where the Subroutine and Interrupt Stacks are located. This Stack space in the data SRAM must be defined by the
program before any subroutine calls are executed or interrupts are enabled. The Stack
Pointer must be set to point above $60. The Stack Pointer is decremented by one when
data is pushed onto the Stack with the PUSH instruction, and it is decremented by two
when the return address is pushed onto the Stack with subroutine call and interrupt. The
Stack Pointer is incremented by one when data is popped from the Stack with the POP
instruction, and it is incremented by two when data is popped from the Stack with return
from subroutine RET or return from interrupt RETI.
Reset and Interrupt
Handling
The ATmega163 provides 17 different interrupt sources. These interrupts and the separate Reset Vector, each have a separate Program Vector in the Program Memory
space. All interrupts are assigned individual enable bits which must be set (one)
together with the I-bit in the Status Register in order to enable the interrupt.
The lowest addresses in the Program Memory space are automatically defined as the
Reset and Interrupt Vectors. The complete list of vectors is shown in Table 3. The list
also determines the priority levels of the different interrupts. The lower the address the
higher is the priority level. RESET has the highest priority, and next is INT0 – the External Interrupt Request 0, etc.
Table 3. Reset and Interrupt Vectors
Vector No.
Program
Address
Source
Interrupt Definition
1
$000(1)
RESET
External Pin, Power-on Reset, Brown-out
Reset and Watchdog Reset
2
$002
INT0
External Interrupt Request 0
3
$004
INT1
External Interrupt Request 1
4
$006
TIMER2 COMP
Timer/Counter2 Compare Match
5
$008
TIMER2 OVF
Timer/Counter2 Overflow
6
$00A
TIMER1 CAPT
Timer/Counter1 Capture Event
7
$00C
TIMER1 COMPA
Timer/Counter1 Compare Match A
8
$00E
TIMER1 COMPB
Timer/Counter1 Compare Match B
9
$010
TIMER1 OVF
Timer/Counter1 Overflow
10
$012
TIMER0 OVF
Timer/Counter0 Overflow
11
$014
SPI, STC
Serial Transfer Complete
12
$016
UART, RXC
UART, Rx Complete
21
1142E–AVR–02/03
Table 3. Reset and Interrupt Vectors (Continued)
Vector No.
Program
Address
13
Source
Interrupt Definition
$018
UART, UDRE
UART Data Register Empty
14
$01A
UART, TXC
UART, Tx Complete
15
$01C
ADC
ADC Conversion Complete
16
$01E
EE_RDY
EEPROM Ready
17
$020
ANA_COMP
Analog Comparator
$022
TWI
Two-wire Serial Interface
18
Note:
1. When the BOOTRST Fuse is programmed, the device will jump to the Boot Loader
address at reset, see “Boot Loader Support” on page 134.
The most typical and general program setup for the Reset and Interrupt Vector
Addresses in ATmega163 is:
Address
Labels Code
Comments
$000
jmp
RESET
; Reset Handler
$002
jmp
EXT_INT0
; IRQ0 Handler
$004
jmp
EXT_INT1
; IRQ1 Handler
$006
jmp
TIM2_COMP
; Timer2 Compare Handler
$008
jmp
TIM2_OVF
; Timer2 Overflow Handler
$00a
jmp
TIM1_CAPT
; Timer1 Capture Handler
$00c
jmp
TIM1_COMPA ; Timer1 Compare A Handler
$00e
jmp
TIM1_COMPB ; Timer1 Compare B Handler
$010
jmp
TIM1_OVF
; Timer1 Overflow Handler
$012
jmp
TIM0_OVF
; Timer0 Overflow Handler
$014
jmp
SPI_STC
; SPI Transfer Complete Handler
$016
jmp
UART_RXC
; UART RX Complete Handler
$018
jmp
UART_DRE
; UDR Empty Handler
$01a
jmp
UART_TXC
; UART TX Complete Handler
$01c
jmp
ADC
$01e
jmp
EE_RDY
$020
jmp
ANA_COMP
$022
jmp
TWI
; ADC Conversion Complete Interrupt Handler
; EEPROM Ready Handler
; Analog Comparator Handler
; Two-wire Serial Interface Interrupt Handler
;
$024
ldi
r16,high(RAMEND) ; Main program start
$025
out
SPH,r16
$026
ldi
r16,low(RAMEND)
$027
out
SPL,r16
...
22
MAIN:
...
; Set stack pointer to top of RAM
...
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
When the BOOTRST Fuse is programmed and the Boot section size set to 512 bytes,
the most typical and general program setup for the Reset and Interrupt Vector
Addresses in ATmega163 is:
Address
Labels Code
$002
...
jmp
...
$022
Comments
EXT_INT0
; IRQ0 Handler
...
jmp
TWI
; Two-wire Serial Interface Interrupt Handler
ldi
r16,high(RAMEND) ; Main program start
$025
out
SPH,r16
$026
ldi
r16,low(RAMEND)
$027
out
SPL,r16
$028
<instr> xxx
;
$024
MAIN:
; Set stack pointer to top of RAM
;
.org $1f00
$1f00
Reset Sources
jmp
RESET
; Reset Handler
The ATmega163 has four sources of reset:
•
Power-on Reset. The MCU is reset when the supply voltage is below the Power-on
Reset threshold (VPOT).
•
External Reset. The MCU is reset when a low level is present on the RESET pin for
more than 500 ns.
•
Watchdog Reset. The MCU is reset when the Watchdog Timer period expires and
the Watchdog is enabled.
•
Brown-out Reset. The MCU is reset when the supply voltage VCC is below the
Brown-out Reset threshold (VBOT).
During Reset, all I/O Registers are set to their initial values, and the program starts execution from address $000 (unless the BOOTRST Fuse is programmed, as explained
above). The instruction placed in this address location must be a JMP – absolute jump –
instruction to the reset handling routine. If the program never enables an interrupt
source, the Interrupt Vectors are not used, and regular program code can be placed at
these locations. The circuit diagram in Figure 24 shows the Reset Logic. Table 4 and
Table 5 define the timing and electrical parameters of the reset circuitry.
23
1142E–AVR–02/03
Figure 24. Reset Logic
DATA BUS
PORF
BORF
EXTRF
WDRF
MCU Status
Register (MCUSR)
Power-on
Reset Circuit
VCC
Internal Reset
Brown-out
Reset Circuit
BODEN
BODLEVEL
100-500kW
SPIKE
FILTER
Reset Circuit
Counter Reset
RESET
Watchdog
Timer
On-chip
RC Oscillator
Clock
Generator
CK
Delay Counters
TIMEOUT
CKSEL[3:0]
Table 4. Reset Characteristics (VCC = 5.0V)
Symbol
Parameter
VPOT
Typ
Max
Units
Power-on Reset Threshold
Voltage (rising)
1.0
1.4
1.8
V
Power-on Reset Threshold
Voltage (falling)(1)
0.4
0.6
0.8
V
–
–
0.85 V CC
V
(BODLEVEL = 1)
2.4
2.7
3.2
(BODLEVEL = 0)
3.5
4.0
4.5
RESET Pin Threshold
Voltage
VBOT
Brown-out Reset Threshold
Voltage
Notes:
24
Min
VRST
Condition
V
1. The Power-on Reset will not work unless the supply voltage has been below VPOT
(falling).
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Table 5. Reset Delay Selections(1)
CKSEL(2)
Start-up Time,
VCC = 2.7V,
BODLEVEL
Unprogrammed
Start-up Time,
VCC = 4.0V,
BODLEVEL
Programmed
Recommended Usage(3)
0000
4.2 ms + 6 CK
5.8 ms + 6 CK
Ext. Clock, fast rising power
0001
(4)
(5)
30 µs + 6 CK
10 µs + 6 CK
Ext. Clock, BOD enabled
67 ms + 6 CK
92 ms + 6 CK
Int. RC Oscillator, slowly rising power
0011
4.2 ms + 6 CK
5.8 ms + 6 CK
Int. RC Oscillator, fast rising power
0100
30 µs + 6 CK(4)
10 µs + 6 CK(5)
Int. RC Oscillator, BOD enabled
0101
67 ms + 6 CK
92 ms + 6 CK
Ext. RC Oscillator, slowly rising power
0110
4.2 ms + 6 CK
5.8 ms + 6 CK
Ext. RC Oscillator, fast rising power
0111
(4)
30 µs + 6 CK
(5)
1000
67ms + 32K CK
92 ms + 32K CK
Ext. Low-frequency Crystal
1001
67 ms + 1K CK
92 ms + 1K CK
Ext. Low-frequency Crystal
1010
67 ms + 16K CK
92 ms + 16K CK
Crystal Oscillator, slowly rising power
1011
4.2 ms + 16K CK
5.8 ms + 16K CK
Crystal Oscillator, fast rising power
1100
30 µs + 16K CK(4)
10 µs + 16K CK(5)
Crystal Oscillator, BOD enabled
1101
67 ms + 1K CK
92 ms + 1K CK
Ceramic Resonator/Ext. Clock, slowly
rising power
1110
4.2 ms + 1K CK
5.8 ms + 1K CK
Ceramic Resonator, fast rising power
1111
(4)
(5)
(6)
0010
Notes:
1.
2.
3.
4.
5.
6.
30 µs + 1K CK
10 µs + 6 CK
10 µs + 1K CK
Ext. RC Oscillator, BOD enabled
Ceramic Resonator, BOD enabled
On power-up, the start-up time is increased with typ. 0.6 ms.
“1” means unprogrammed, “0” means programmed.
For possible clock selections, see “Clock Options” on page 5.
When BODEN is programmed, add 100 µs.
When BODEN is programmed, add 25 µs.
Default value.
Table 5 shows the Start-up Times from Reset. When the CPU wakes up from Powerdown or Power-save, only the clock counting part of the start-up time is used. The
Watchdog Oscillator is used for timing the real time part of the start-up time. The number
of WDT Oscillator cycles used for each time-out is shown in Table 6.
The frequency of the Watchdog Oscillator is voltage dependent as shown in the Electrical Characteristics section. The device is shipped with CKSEL = “0010” (Int. RC
Oscillator, slowly rising power).
25
1142E–AVR–02/03
Table 6. Number of Watchdog Oscillator Cycles(1)
BODLEVEL
VCC Condition
Time-out
Number of Cycles
Unprogrammed
2.7V
30 µs
8
Unprogrammed
2.7V
130 µs
32
Unprogrammed
2.7V
4.2 ms
1K
Unprogrammed
2.7V
67 ms
16K
Programmed
4.0V
10 µs
8
Programmed
4.0V
35 µs
32
Programmed
4.0V
5.8 ms
4K
Programmed
4.0V
92 ms
64K
Note:
Power-on Reset
1. The Bodlevel Fuse can be used to select start-up times even if the Brown-out Detection is disabled (BODEN Fuse unprogrammed).
A Power-on Reset (POR) pulse is generated by an On-chip detection circuit. The detection level is defined in Table 4. The POR is activated whenever V CC is below the
detection level. The POR circuit can be used to trigger the Start-up Reset, as well as to
detect a failure in supply voltage.
A Power-on Reset (POR) circuit ensures that the device is reset from Power-on. Reaching the Power-on Reset threshold voltage invokes a delay counter, which determines
the delay, for which the device is kept in RESET after VCC rise. The Time-out Period of
the delay counter can be defined by the user through the CKSEL Fuses. The different
selections for the delay period are presented in Table 5. The RESET signal is activated
again, without any delay, when the VCC decreases below detection level.
Figure 25. MCU Start-up, RESET Tied to VCC.
VCC
RESET
TIME-OUT
VPOT
VRST
tTOUT
INTERNAL
RESET
26
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Figure 26. MCU Start-up, RESET Extended Externally
VCC
RESET
VPOT
VRST
TIME-OUT
tTOUT
INTERNAL
RESET
External Reset
An External Reset is generated by a low level on the RESET pin. Reset pulses longer
than 500 ns will generate a Reset, even if the clock is not running. Shorter pulses are
not guaranteed to generate a Reset. When the applied signal reaches the Reset
Threshold Voltage – VRST on its positive edge, the delay timer starts the MCU after the
Time-out Period tTOUT has expired.
Figure 27. External Reset During Operation
Brown-out Detection
ATmega163 has an On-chip Brown-out Detection (BOD) circuit for monitoring the VCC
level during the operation. The BOD circuit can be enabled/disabled by the fuse
BODEN. When the BOD is enabled (BODEN programmed), and VCC decreases to a
value below the trigger level, the Brown-out Reset is immediately activated. When VCC
increases above the trigger level, the Brown-out Reset is deactivated after a delay. The
delay is defined by the user in the same way as the delay of POR signal, in Table 5. The
trigger level for the BOD can be selected by the fuse BODLEVEL to be 2.7V
(BODLEVEL unprogrammed), or 4.0V (BODLEVEL programmed). The trigger level has
a hysteresis of 50 mV to ensure spike free Brown-out Detection.
The BOD circuit will only detect a drop in VCC if the voltage stays below the trigger level
for longer than 9 µs for trigger level 4.0V, 21 µs for trigger level 2.7V (typical values).
27
1142E–AVR–02/03
Figure 28. Brown-out Reset During Operation
VCC
VBOT+
VBOT-
RESET
tTOUT
TIME-OUT
INTERNAL
RESET
The hysteresis on VBOT: VBOT+ = VBOT + 25 mV, VBOT- = VBOT - 25 mV
Watchdog Reset
When the Watchdog times out, it will generate a short reset pulse of 1 XTAL cycle duration. On the falling edge of this pulse, the delay timer starts counting the Time-out Period
tTOUT. Refer to page 60 for details on operation of the Watchdog Timer.
Figure 29. Watchdog Reset During Operation
1 CK Cycle
MCU Status Register –
MCUSR
The MCU Status Register provides information on which reset source caused an MCU
Reset.
Bit
7
6
5
4
3
2
1
0
$34 ($54)
–
–
–
–
WDRF
BORF
EXTRF
PORF
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
MCUSR
See Bit Description
• Bits 7..4 – Res: Reserved Bits
These bits are reserved bits in the ATmega163 and always read as zero.
• Bit 3 – WDRF: Watchdog Reset Flag
This bit is set if a Watchdog Reset occurs. The bit is reset by a Power-on Reset, or by
writing a logic zero to the Flag.
28
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
• Bit 2 – BORF: Brown-out Reset Flag
This bit is set if a Brown-out Reset occurs. The bit is reset by a Power-on Reset, or by
writing a logic zero to the Flag.
• Bit 1 – EXTRF: External Reset Flag
This bit is set if an External Reset occurs. The bit is reset by a Power-on Reset, or by
writing a logic zero to the flag.
• Bit 0 – PORF: Power-on Reset Flag
This bit is set if a Power-on Reset occurs. The bit is reset only by writing a logic zero to
the flag.
To make use of the Reset Flags to identify a reset condition, the user should read and
then reset the MCUSR as early as possible in the program. If the register is cleared
before another reset occurs, the source of the reset can be found by examining the
Reset Flags.
Internal Voltage Reference
ATmega163 features an internal bandgap reference with a nominal voltage of 1.22V.
This reference is used for Brown-out Detection, and it can be used as an input to the
Analog Comparator and ADC. The 2.56V reference to the ADC is also generated from
the internal bandgap reference.
Voltage Reference Enable
Signals and Start-up Time
To save power, the reference is not always turned on. The reference is on during the following situations:
1. When the BOD is enabled (by programming the BODEN Fuse)
2. When the bandgap reference is connected to the Analog Comparator (by setting
the ACBG bit in ACSR).
3. When the ADC is enabled.
Thus, when the BOD is not enabled, after setting the ACBG bit, the user must always
allow the reference to start up before the output from the Analog Comparator is used.
The bandgap reference uses typically 10 µA, and to reduce power consumption in
Power-down mode, the user can avoid the three conditions above to ensure that the reference is turned off before entering Power-down mode.
Interrupt Handling
The ATmega163 has two 8-bit Interrupt Mask Control Registers: GIMSK – General
Interrupt Mask Register and TIMSK – Timer/Counter Interrupt Mask Register.
When an interrupt occurs, the Global Interrupt Enable I-bit is cleared (zero) and all interrupts are disabled. The user software must set (one) the I-bit to enable nested
interrupts. The I-bit is set (one) when a Return from Interrupt instruction – RETI – is
executed.
When the Program Counter is vectored to the actual Interrupt Vector in order to execute
the interrupt handling routine, hardware clears the corresponding flag that generated the
interrupt. Some of the interrupt flags can also be cleared by writing a logic one to the flag
bit position(s) to be cleared.
If an interrupt condition occurs when the corresponding interrupt enable bit is cleared
(zero), the Interrupt Flag will be set and remembered until the interrupt is enabled, or the
flag is cleared by software.
29
1142E–AVR–02/03
If one or more interrupt conditions occur when the Global Interrupt Enable bit is cleared
(zero), the corresponding interrupt flag(s) will be set and remembered until the Global
Interrupt Enable bit is set (one), and will be executed by order of priority.
Note that external level interrupt does not have a flag, and will only be remembered for
as long as the interrupt condition is present.
Note that the Status Register is not automatically stored when entering an interrupt routine and restored when returning from an interrupt routine. This must be handled by
software.
Interrupt Response Time
The interrupt execution response for all the enabled AVR interrupts is four clock cycles
minimum. After four clock cycles the Program Vector address for the actual interrupt
handling routine is executed. During this four clock cycle period, the Program Counter
(13 bits) is pushed onto the Stack. The vector is normally a jump to the interrupt routine,
and this jump takes three clock cycles. If an interrupt occurs during execution of a multicycle instruction, this instruction is completed before the interrupt is served. If an interrupt occurs when the MCU is in sleep mode, the interrupt execution response time is
increased by four clock cycles.
A return from an interrupt handling routine takes four clock cycles. During these four
clock cycles, the Program Counter (two bytes) is popped back from the Stack, the Stack
Pointer is incremented by two, and the I Flag in SREG is set. When AVR exits from an
interrupt, it will always return to the main program and execute one more instruction
before any pending interrupt is served.
The General Interrupt Mask
Register – GIMSK
Bit
7
6
5
4
3
2
1
$3B ($5B)
INT1
INT0
–
–
–
–
–
0
–
Read/Write
R/W
R/W
R
R
R
R
R
R
Initial Value
0
0
x
0
0
0
0
0
GIMSK
• Bit 7 – INT1: External Interrupt Request 1 Enable
When the INT1 bit is set (one) and the I-bit in the Status Register (SREG) is set (one),
the external pin interrupt is activated. The Interrupt Sense Control1 bits 1/0 (ISC11 and
ISC10) in the MCU general Control Register (MCUCR) define whether the external
interrupt is activated on rising and/or falling edge of the INT1 pin or level sensed. Activity
on the pin will cause an interrupt request even if INT1 is configured as an output. The
corresponding interrupt of External Interrupt Request 1 is executed from program memory address $004. See also “External Interrupts”.
• Bit 6 – INT0: External Interrupt Request 0 Enable
When the INT0 bit is set (one) and the I-bit in the Status Register (SREG) is set (one),
the external pin interrupt is activated. The Interrupt Sense Control0 bits 1/0 (ISC01 and
ISC00) in the MCU General Control Register (MCUCR) define whether the external
interrupt is activated on rising or falling edge of the INT0 pin or level sensed. Activity on
the pin will cause an interrupt request even if INT0 is configured as an output. The corresponding interrupt of External Interrupt Request 0 is executed from Program Memory
address $002. See also “External Interrupts.”
• Bits 5 – Res: Reserved Bits
This bit is reserved in the ATmega163 and the read value is undefined.
30
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
• Bits 4..0 – Res: Reserved Bits
These bits are reserved bits in the ATmega163 and always read as zero.
The General Interrupt Flag
Register – GIFR
Bit
7
6
5
4
3
2
1
$3A ($5A)
INTF1
INTF0
–
–
–
–
–
0
–
Read/Write
R/W
R/W
R
R
R
R
R
R
Initial Value
0
0
0
0
0
0
0
0
GIFR
• Bit 7 – INTF1: External Interrupt Flag1
When an edge on the INT1 pin triggers an interrupt request, the correspnding Interrupt
Flag, INTF1, becomes set (one). If the I-bit in SREG and the corresponding Interrupt
Enable bit, INT1 in GIMSK are set (one), the MCU will jump to the Interrupt Vector. The
Flag is cleared when the interrupt routine is executed. Alternatively, the Flag can be
cleared by writing a logical one to it. This Flag is always cleared when INT1 is configured as a level interrupt.
• Bit 6 – INTF0: External Interrupt Flag0
When an event on the INT0 pin triggers an interrupt request, the corresponding Interrupt
Flag, INTF0 becomes set (one). If the I-bit in SREG and the corresponding Interrupt
Enable bit, INT0 in GIMSK are set (one), the MCU will jump to the Interrupt Vector. The
Flag is cleared when the interrupt routine is executed. Alternatively, the Flag can be
cleared by writing a logical one to it. This Flag is always cleared when INT0 is configured as a level interrupt.
• Bits 5..0 – Res: Reserved Bits
These bits are reserved bits in the ATmega163 and always read as zero.
The Timer/Counter Interrupt
Mask Register – TIMSK
Bit
7
6
5
4
3
2
1
0
OCIE2
TOIE2
TICIE1
OCIE1A
OCIE1B
TOIE1
–
TOIE0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R
R/W
Initial Value
0
0
0
0
0
0
0
0
$39 ($59)
TIMSK
• Bit 7 – OCIE2: Timer/Counter2 Output Compare Match Interrupt Enable
When the OCIE2 bit is set (one) and the I-bit in the Status Register is set (one), the
Timer/Counter2 Compare Match Interrupt is enabled. The corresponding interrupt (at
vector $006) is executed if a Compare Match in Timer/Counter2 occurs, i.e., when the
OCF2 bit is set in the Timer/Counter Interrupt Flag Register – TIFR.
• Bit 6 – TOIE2: Timer/Counter2 Overflow Interrupt Enable
When the TOIE2 bit is set (one) and the I-bit in the Status Register is set (one), the
Timer/Counter2 Overflow Interrupt is enabled. The corresponding interrupt (at vector
$008) is executed if an overflow in Timer/Counter2 occurs, i.e., when the TOV2 bit is set
in the Timer/Counter Interrupt Flag Register – TIFR.
• Bit 5 – TICIE1: Timer/Counter1 Input Capture Interrupt Enable
When the TICIE1 bit is set (one) and the I-bit in the Status Register is set (one), the
Timer/Counter1 Input Capture Event Interrupt is enabled. The corresponding interrupt
31
1142E–AVR–02/03
(at vector $00A) is executed if a capture triggering event occurs on PD6 (ICP), i.e., when
the ICF1 bit is set in the Timer/Counter Interrupt Flag Register – TIFR.
• Bit 4 – OCIE1A: Timer/Counter1 Output CompareA Match Interrupt Enable
When the OCIE1A bit is set (one) and the I-bit in the Status Register is set (one), the
Timer/Counter1 Compare A Match Interrupt is enabled. The corresponding interrupt (at
vector $00C) is executed if a Compare A Match in Timer/Counter1 occurs, i.e., when the
OCF1A bit is set in the Timer/Counter Interrupt Flag Register – TIFR.
• Bit 3 – OCIE1B: Timer/Counter1 Output CompareB Match Interrupt Enable
When the OCIE1B bit is set (one) and the I-bit in the Status Register is set (one), the
Timer/Counter1 Compare B Match Interrupt is enabled. The corresponding interrupt (at
vector $00E) is executed if a Compare B Match in Timer/Counter1 occurs, i.e., when the
OCF1B bit is set in the Timer/Counter Interrupt Flag Register – TIFR.
• Bit 2 – TOIE1: Timer/Counter1 Overflow Interrupt Enable
When the TOIE1 bit is set (one) and the I-bit in the Status Register is set (one), the
Timer/Counter1 Overflow Interrupt is enabled. The corresponding interrupt (at vector
$010) is executed if an overflow in Timer/Counter1 occurs, i.e., when the TOV1 bit is set
in the Timer/Counter Interrupt Flag Register – TIFR.
• Bit 1 – Res: Reserved Bit
This bit is a reserved bit in the ATmega163 and always reads as zero.
• Bit 0 – TOIE0: Timer/Counter0 Overflow Interrupt Enable
When the TOIE0 bit is set (one) and the I-bit in the Status Register is set (one), the
Timer/Counter0 Overflow Interrupt is enabled. The corresponding interrupt (at vector
$012) is executed if an overflow in Timer/Counter0 occurs, i.e., when the TOV0 bit is set
in the Timer/Counter Interrupt Flag Register – TIFR.
The Timer/Counter Interrupt
Flag Register – TIFR
Bit
7
6
5
4
3
2
1
0
OCF2
TOV2
ICF1
OCF1A
OCF1B
TOV1
–
TOV0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R
R/W
Initial Value
0
0
0
0
0
0
x
0
$38 ($58)
TIFR
• Bit 7 – OCF2: Output Compare Flag2
The OCF2 bit is set (one) when a Compare Match occurs between the Timer/Counter2
and the data in OCR2 – Output Compare Register2. OCF2 is cleared by hardware when
executing the corresponding Interrupt Handling Vector. Alternatively, OCF2 is cleared
by writing a logic one to the flag. When the I-bit in SREG, and OCIE2 (Timer/Counter2
Compare Match Interrupt Enable), and the OCF2 are set (one), the Timer/Counter2
Compare Match Interrupt is executed.
• Bit 6 – TOV2: Timer/Counter2 Overflow Flag
The TOV2 bit is set (one) when an overflow occurs in Timer/Counter2. TOV2 is cleared
by hardware when executing the corresponding inteRrupt Handling Vector. Alternatively, TOV2 is cleared by writing a logic one to the flag. When the SREG I-bit, and
TOIE2 (Timer/Counter2 Overflow Interrupt Enable), and TOV2 are set (one), the
32
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Timer/Counter2 Overflow Interrupt is executed. In up/down PWM mode, this bit is set
when Timer/Counter2 changes counting direction at $00.
• Bit 5 – ICF1: Input Capture Flag1
The ICF1 bit is set (one) to Flag an Input Capture Event, indicating that the
Timer/Counter1 value has been transferred to the Input Capture Register – ICR1. ICF1
is cleared by hardware when executing the corresponding Interrupt Handling Vector.
Alternatively, ICF1 is cleared by writing a logic one to the flag.
• Bit 4 – OCF1A: Output Compare Flag 1A
The OCF1A bit is set (one) when a Compare Match occurs between the Timer/Counter1
and the data in OCR1A – Output Compare Register 1A. OCF1A is cleared by hardware
when executing the corresponding Interrupt Handling Vector. Alternatively, OCF1A is
cleared by writing a logic one to the flag. When the I-bit in SREG, and OCIE1A
(Timer/Counter1 Compare Match Interrupt A Enable), and the OCF1A are set (one), the
Timer/Counter1A Compare Match Interrupt is executed.
• Bit 3 – OCF1B: Output Compare Flag 1B
The OCF1B bit is set (one) when a Compare Match occurs between the Timer/Counter1
and the data in OCR1B – Output Compare Register 1B. OCF1B is cleared by hardware
when executing the corresponding Interrupt Handling Vector. Alternatively, OCF1B is
cleared by writing a logic one to the flag. When the I-bit in SREG, and OCIE1B
(Timer/Counter1 Compare Match Interrupt B Enable), and the OCF1B are set (one), the
Timer/Counter1B Compare Match Interrupt is executed.
• Bit 2 – TOV1: Timer/Counter1 Overflow Flag
The TOV1 is set (one) when an overflow occurs in Timer/Counter1. TOV1 is cleared by
hardware when executing the corresponding Interrupt Handling Vector. Alternatively,
TOV1 is cleared by writing a logic one to the flag. When the I-bit in SREG, and TOIE1
( Time r /C o u n te r1 O ve r flo w In te r ru p t En a b le ), a n d TO V 1 a r e se t ( o ne ) , th e
Timer/Counter1 Overflow Interrupt is executed. In up/down PWM mode, this bit is set
when Timer/Counter1 changes counting direction at $0000.
• Bit 1 – Res: Reserved Bit
This bit is a reserved bit in the ATmega163 and the read value is undefined.
• Bit 0 – TOV0: Timer/Counter0 Overflow Flag
The bit TOV0 is set (one) when an overflow occurs in Timer/Counter0. TOV0 is cleared
by hardware when executing the corresponding Interrupt Handling Vector. Alternatively,
TOV0 is cleared by writing a logic one to the flag. When the SREG I-bit, and TOIE0
( Time r /C o u n te r0 O ve r flo w In te r ru p t En a b le ), a n d TO V 0 a r e se t ( o ne ) , th e
Timer/Counter0 Overflow interrupt is executed.
External Interrupts
The external interrupts are triggered by the INT0 and INT1 pins. Observe that, if
enabled, the interrupts will trigger even if the INT0/INT1 pins are configured as outputs.
This feature provides a way of generating a software interrupt. The external interrupts
can be triggered by a falling or rising edge or a low level. This is set up as indicated in
the specification for the MCU Control Register – MCUCR. When the external interrupt is
enabled and is configured as level triggered, the interrupt will trigger as long as the pin is
held low.
33
1142E–AVR–02/03
MCU Control Register –
MCUCR
The MCU Control Register contains control bits for general MCU functions.
Bit
7
6
5
4
3
2
1
0
$35 ($55)
–
SE
SM1
SM0
ISC11
ISC10
ISC01
ISC00
Read/Write
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
MCUCR
• Bit 7 – Res: Reserved Bit
This bit is a reserved bit in the ATmega163 and always reads as zero.
• Bit 6 – SE: Sleep Enable
The SE bit must be set (one) to make the MCU enter the sleep mode when the SLEEP
instruction is executed. To avoid the MCU entering the sleep mode unless it is the programmers purpose, it is recommended to set the Sleep Enable SE bit just before the
execution of the SLEEP instruction.
• Bits 5, 4 – SM1/SM0: Sleep Mode Select Bits 1 and 0
These bits select between the three available sleep modes as shown in Table 7.
Table 7. Sleep Mode Select
SM1
SM0
Sleep Mode
0
0
Idle
0
1
ADC Noise Reduction
1
0
Power-down
1
1
Power-save
• Bits 3, 2 – ISC11, ISC10: Interrupt Sense Control 1 Bit 1 and Bit 0
The External Interrupt 1 is activated by the external pin INT1 if the SREG I-Flag and the
corresponding interrupt mask in the GIMSK are set. The level and edges on the external
INT1 pin that activate the interrupt are defined in Table 8. The value on the INT1 pin is
sampled before detecting edges. If edge or toggle interrupt is selected, pulses that last
longer than one clock period will generate an interrupt. Shorter pulses are not guaranteed to generate an interrupt. If low level interrupt is selected, the low level must be held
until the completion of the currently executing instruction to generate an interrupt.
Table 8. Interrupt 1 Sense Control
34
ISC11
ISC10
Description
0
0
The low level of INT1 generates an interrupt request.
0
1
Any logical change on INT1 generates an interrupt request.
1
0
The falling edge of INT1 generates an interrupt request.
1
1
The rising edge of INT1 generates an interrupt request.
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
• Bit 1, 0 – ISC01, ISC00: Interrupt Sense Control 0 Bit 1 and Bit 0
The External Interrupt 0 is activated by the external pin INT0 if the SREG I-Flag and the
corresponding interrupt mask are set. The level and edges on the external INT0 pin that
activate the interrupt are defined in Table 9. The value on the INT0 pin is sampled
before detecting edges. If edge or toggle interrupt is selected, pulses that last longer
than one clock period will generate an interrupt. Shorter pulses are not guaranteed to
generate an interrupt. If low level interrupt is selected, the low level must be held until
the completion of the currently executing instruction to generate an interrupt.
Table 9. Interrupt 0 Sense Control
ISC01
ISC00
Description
0
0
The low level of INT0 generates an interrupt request.
0
1
Any logical change on INT0 generates an interrupt request.
1
0
The falling edge of INT0 generates an interrupt request.
1
1
The rising edge of INT0 generates an interrupt request.
Sleep Modes
To enter any of the four sleep modes, the SE bit in MCUCR must be set (one) and a
SLEEP instruction must be executed. The SM1 and SM0 bits in the MCUCR Register
select which sleep mode (Idle, ADC Noise Reduction, Power-down, or Power-save) will
be activated by the SLEEP instruction. See Table 7 for a summary. If an enabled interrupt occurs while the MCU is in a sleep mode, the MCU wakes up. The MCU is then
halted for four cycles, executes the interrupt routine, and resumes execution from the
instruction following SLEEP. The contents of the Register File, SRAM, and I/O memory
are unaltered when the device wakes up from sleep. If a Reset occurs during sleep
mode, the MCU wakes up and executes from the Reset Vector.
Idle Mode
When the SM1/SM0 bits are set to 00, the SLEEP instruction makes the MCU enter Idle
mode, stopping the CPU but allowing SPI, UART, Analog Comparator, ADC, Two-wire
Serial Interface, Timer/Counters, Watchdog, and the interrupt system to continue operating (if enabled). This enables the MCU to wake up from external triggered interrupts
as well as internal ones like the Timer Overflow and UART Receive Complete interrupts.
If wake-up from the Analog Comparator interrupt is not required, the Analog Comparator
can be powered down by setting the ACD bit in the Analog Comparator Control and Status Register – ACSR. This will reduce power consumption in Idle Mode. If the ADC is
enabled, a conversion starts automatically when this mode is entered.
ADC Noise Reduction Mode
When the SM1/SM0 bits are set to 01, the SLEEP instruction makes the MCU enter
ADC Noise Reduction mode, stopping the CPU but allowing the ADC, the external interrupts, the Two-wire Serial Interface address watch, Timer/Counter2 and the Watchdog
to continue operating (if enabled). This improves the noise environment for the ADC,
enabling higher resolution measurements. If the ADC is enabled, a conversion starts
automatically when this mode is entered. Apart from the ADC Conversion Complete
interrupt, only an External Reset, a Watchdog Reset (if enabled), a Brown-out Reset, a
Two-wire Serial Interface address match interrupt, or an external level interrupt can
wake up the MCU from ADC Noise Reduction Mode. A Timer/Counter2 Output Compare or overflow event will wake up the MCU, but will not generate an interrupt unless
Timer/Counter2 is clocked asynchronously.
In future devices this is subject to change. It is recommended for future code compatibility to disable Timer/Counter2 interrupts during ADC Noise Reduction mode if the
Timer/Counter2 is clocked synchronously.
35
1142E–AVR–02/03
Power-down Mode
When the SM1/SM0 bits are 10, the SLEEP instruction makes the MCU enter Powerdown mode. In this mode, the external Oscillator is stopped, while the external interrupts, the Two-wire Serial Interface address match, and the Watchdog continue
operating (if enabled). Only an External Reset, a Watchdog Reset, a Brown-out Reset, a
Two-wire Serial Interface address match interrupt, or an external level interrupt can
wake up the MCU.
Note that if a level triggered interrupt is used for wake-up from Power-down mode, the
changed level must be held for some time to wake up the MCU. This makes the MCU
less sensitive to noise. The changed level is sampled twice by the Watchdog Oscillator
clock, and if the input has the required level during this time, the MCU will wake up. The
period of the Watchdog Oscillator is 1 µs (nominal) at 5.0V and 25°C. The frequency of
the Watchdog Oscillator is voltage dependent as shown in the Electrical Characteristics
section.
When waking up from Power-down mode, there is a delay from the wake-up condition
occurs until the wake-up becomes effective. This allows the clock to restart and become
stable after having been stopped. The wake-up period is defined by the same CKSEL
Fuses that define the Reset Time-out period, as seen in Table 5 on page 25.
Power-save Mode
When the SM1/SM0 bits are 11, the SLEEP instruction forces the MCU into the Powersave mode. This mode is identical to Power-down, with one exception:
If Timer/Counter2 is clocked asynchronously, i.e., the AS2 bit in ASSR is set,
Timer/Counter2 will run during sleep. The device can wake up from either Timer Overf lo w o r O u tp u t C o m p a r e e v e n t fr o m Ti me r /C o u n te r2 i f t h e c o r r e s p o n d i n g
Timer/Counter2 interrupt enable bits are set in TIMSK, and the global interrupt enable
bit in SREG is set.
If the asynchronous timer is NOT clocked asynchronously, Power-down mode is recommended instead of Power-save mode because the contents of the registers in the
asynchronous timer should be considered undefined after wake-up in Power-save mode
if AS2 is 0.
36
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Calibrated Internal RC
Oscillator
Oscillator Calibration Register
– OSCCAL
The calibrated internal Oscillator provides a fixed 1 MHz (nominal) clock at 5V and
25°C. This clock may be used as the system clock. See the section “Clock Options” on
page 5 for information on how to select this clock as the system clock. This Oscillator
can be calibrated by writing the calibration byte to the OSCCAL Register. When this
Oscillator is used as the chip clock, the Watchdog Oscillator will still be used for the
Watchdog Timer and for the Reset Time-out. At 5V and 25oC, the pre-programmed calibration byte gives a frequency within ± 1% of the nominal frequency. For details on how
to use the pre-programmed calibration value, see “Calibration Byte” on page 144.
Bit
7
6
5
4
3
2
1
0
CAL7
CAL6
CAL5
CAL4
CAL3
CAL2
CAL1
CAL0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
$31 ($51)
• Bits 7..0 – CAL7..0: Oscillator Calibration Value
Writing the calibration byte to this address will trim the internal Oscillator to remove process variations from the Oscillator frequency. When OSCCAL is zero, the lowest
available frequency is chosen. Writing non-zero values to this register will increase the
frequency of the internal Oscillator. Writing $FF to the register gives the highest available frequency.
The calibrated Oscillator is used to time EEPROM and Flash access. If EEPROM or
Flash is written, do not calibrate to more than 10% above the nominal frequency. Otherwise, the EEPROM or Flash write operation may fail. Note that the Oscillator is intended
for calibration to 1.0MHz, thus tuning to other values is not guaranteed.
Table 10. Internal RC Oscillator Frequency Range.
Special Function I/O Register
– SFIOR
OSCCAL Value
Min Frequency (MHz)
Max Frequency (MHz)
$00
0.5
1.0
$7F
0.7
1.5
$FF
1.0
2.0
Bit
7
6
5
4
3
2
1
0
$30 ($50)
–
–
–
–
ACME
PUD
PSR2
PSR10
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
SFIOR
• Bit 7..4 – Res: Reserved Bits
These bits are reserved bits in the ATmega163 and always read as zero.
• Bit 3 – ACME: Analog Comparator Multiplexer Enable
When this bit is set (one) and the ADC is switched off (ADEN in ADCSR is zero), the
ADC multiplexer selects the negative input to the Analog Comparator. When this bit is
cleared (zero), AIN1 is applied to the negative input of the Analog Comparator. For a
detailed description of this bit, see “Analog Comparator Multiplexed Input” on page 104.
37
1142E–AVR–02/03
• Bit 2 – PUD: Pull-up Disable
When this bit is set (one), all pull-ups on all ports are disabled. If the bit is cleared (zero),
the pull-ups can be individually enabled as described in the chapter “I/O Ports” on page
115.
• Bit 1 – PSR2: Prescaler Reset Timer/Counter2
When this bit is set (one) the Timer/Counter2 Prescaler will be reset. The bit will be
cleared by hardware after the operation is performed. Writing a zero to this bit will have
no effect. This bit will always be read as zero if Timer/Counter2 is clocked by the internal
CPU clock. If this bit is written when Timer/Counter2 is operating in asynchronous
mode. The bit will remain one until the prescaler has been reset. See “Asynchronous
Operation of Timer/Counter2” on page 58 for a detailed description of asynchronous
operation.
• Bit 0 – PSR10: Prescaler Reset Timer/Counter1 and Timer/Counter0
When this bit is set (one) the Timer/Counter1 and Timer/Counter0 Prescaler will be
reset. The bit will be cleared by hardware after the operation is performed. Writing a
zero to this bit will have no effect. Note that Timer/Counter1 and Timer/Counter0 share
the same prescaler and a reset of this prescaler will affect both timers. This bit will
always be read as zero.
38
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Timer/Counters
The ATmega163 provides three general purpose Timer/Counters – two 8-bit T/Cs and
one 16-bit T/C. Timer/Counter2 can optionally be asynchronously clocked from an external Oscillator. This Oscillator is optimized for use with a 32.768 kHz watch crystal,
enabling use of Timer/Counter2 as a Real Time Clock (RTC). Timer/Counter0 and
Timer/Counter1 have individual prescaling selection from the same 10-bit prescaler.
Timer/Counter2 has its own prescaler. Both these prescalers can be reset by setting the
corresponding control bits in the Special Functions I/O Register (SFIOR). These
Timer/Counters can either be used as a timer with an internal clock time-base or as a
counter with an external pin connection which triggers the counting.
Timer/Counter
Prescalers
Figure 30. Prescaler for Timer/Counter0 and Timer/Counter1
Clear
PSR10
TCK1
TCK0
For Timer/Counter0 and Timer/Counter1, the four different prescaled selections are:
CK/8, CK/64, CK/256, and CK/1024, where CK is the Oscillator clock. For the two
Timer/Counter0 and Timer/Counter1, CK, external source, and stop can also be
selected as clock sources. Setting the PSR10 bit in SFIOR resets the prescaler. This
allows the user to operate with a predictable prescaler. Note that Timer/Counter1 and
Timer/Counter0 share the same prescaler and a Prescaler Reset will affect both
Timer/Counters.
39
1142E–AVR–02/03
Figure 31. Prescaler for Timer/Counter2
PCK2
PSR2
PCK2/1024
PCK2/256
PCK2/128
AS2
PCK2/64
10-BIT T/C PRESCALER
Clear
PCK2/32
TOSC1
PCK2/8
CK
0
CS20
CS21
CS22
TIMER/COUNTER2 CLOCK SOURCE
TCK2
The clock source for Timer/Counter2 is named PCK2. PCK2 is by default connected to
the main system clock CK. By setting the AS2 bit in ASSR, Timer/Counter2 is asynchronously clocked from the PC6(TOSC1) pin. This enables use of Timer/Counter2 as a
Real Time Clock (RTC). When AS2 is set, pins PC6(TOSC1) and PC7(TOSC2) are disconnected from Port C. A crystal can then be connected between the PC6(TOSC1) and
PC7(TOSC2) pins to serve as an independent clock source for Timer/Counter2. The
Oscillator is optimized for use with a 32.768 kHz crystal. Applying an external clock
source to TOSC1 is not recommended. Setting the PSR2 bit in SFIOR resets the prescaler. This allows the user to operate with a predictable prescaler.
8-bit Timer/Counter0
Figure 32 shows the block diagram for Timer/Counter0.
The 8-bit Timer/Counter0 can select clock source from CK, prescaled CK, or an external
pin. In addition it can be stopped as described in “Timer/Counter0 Control Register –
TCCR0” on page 41. The overflow Status Flag is found in “The Timer/Counter Interrupt
Flag Register – TIFR” on page 32. Control signals are found in the Timer/Counter0 Control Register – TCCR0. The interrupt enable/disable settings for Timer/Counter0 are
found in “The Timer/Counter Interrupt Mask Register – TIMSK” on page 31.
When Timer/Counter0 is externally clocked, the external signal is synchronized with the
Oscillator frequency of the CPU. To assure proper sampling of the external clock, the
minimum time between two external clock transitions must be at least one internal CPU
clock period. The external clock signal is sampled on the rising edge of the internal CPU
clock.
The 8-bit Timer/Counter0 features both a high resolution and a high accuracy usage
with the lower prescaling opportunities. Similarly, the high prescaling opportunities make
the Timer/Counter0 useful for lower speed functions or exact timing functions with infrequent actions.
40
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Figure 32. Timer/Counter0 Block Diagram
TOIE0
7
CS00
CS01
CS02
TOV0
TOV1
OCF1A
ICF1
T/C0 CONTROL
REGISTER (TCCR0)
0
TIMER/COUNTER0
(TCNT0)
Timer/Counter0 Control
Register – TCCR0
OCF1B
TIMER INT. FLAG
REGISTER (TIFR)
OCF2
TIMER INT. MASK
REGISTER (TIMSK)
TOV2
OCIE1A
TOIE1
OCIE1B
TICIE1
TOIE2
OCIE2
8-BIT DATA BUS
T/C0 OVERFLOW IRQ
T/C CLK SOURCE
CONTROL
LOGIC
CK
Bit
7
6
5
4
3
2
1
0
$33 ($53)
–
–
–
–
–
CS02
CS01
CS00
Read/Write
R
R
R
R
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
TCCR0
• Bits 7..3 – Res: Reserved Bits
These bits are reserved bits in the ATmega163 and always read as zero.
• Bits 2..0 – CS02, CS01, CS00: Clock Select0, Bit 2, 1, and 0
The Clock Select0 bits 2,1, and 0 define the prescaling source of Timer0.
Table 11. Clock0 Prescale Select
CS02
CS01
CS00
Description
0
0
0
Stop, Timer/Counter0 is stopped.
0
0
1
CK
0
1
0
CK/8
0
1
1
CK/64
1
0
0
CK/256
1
0
1
CK/1024
1
1
0
External Pin T0, falling edge
1
1
1
External Pin T0, rising edge
The Stop condition provides a Timer Enable/Disable function. The prescaled CK modes
are scaled directly from the CK Oscillator clock. If the external pin modes are used for
Timer/Counter0, transitions on PB0/(T0) will clock the counter even if the pin is configured as an output. This feature can give the user SW control of the counting.
41
1142E–AVR–02/03
Timer/Counter 0 – TCNT0
Bit
7
6
5
4
3
2
1
0
$34 ($54)
MSB
LSB
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
TCNT0
The Timer/Counter0 is implemented as an up-counter with read and write access. If the
Timer/Counter0 is written and a clock source is present, the Timer/Counter0 continues
counting in the clock cycle following the write operation.
16-bit Timer/Counter1
Figure 33 shows the block diagram for Timer/Counter1.
Figure 33. Timer/Counter1 Block Diagram
TOV0
8 7
CS11
CS10
CS12
CTC1
ICNC1
ICES1
FOC1B
PWM11
T/C1 CONTROL
REGISTER B (TCCR1B)
PWM10
FOC1A
COM1B1
COM1B0
COM1A1
TOV1
OCF1B
OCF1A
T/C1 CONTROL
REGISTER A (TCCR1A)
COM1A0
TOV1
OCF1B
T/C1 COMPARE T/C1 INPUT
MATCH B IRQ CAPTURE IRQ
TIMER INT. FLAG
REGISTER (TIFR)
ICF1
15
OCF1A
TOV2
OCF2
TOIE0
TOIE1
OCIE1A
OCIE1B
TICIE1
TOIE2
OCIE2
8-BIT DATA BUS
TIMER INT. MASK
REGISTER (TIMSK)
ICF1
T/C1 COMPARE
MATCH A IRQ
T/C1 OVERFLOW IRQ
0
T/C1 INPUT CAPTURE REGISTER (ICR1)
T1
CK
CONTROL
LOGIC
CAPTURE
TRIGGER
15
8 7
0
15
8
7
T/C CLEAR
T/C CLOCK SOURCE
TIMER/COUNTER1 (TCNT1)
UP/DOWN
0
15
15
8
7
8
7
0
16 BIT COMPARATOR
16 BIT COMPARATOR
0
TIMER/COUNTER1 OUTPUT COMPARE REGISTER A
15
8
7
0
TIMER/COUNTER1 OUTPUT COMPARE REGISTER B
The 16-bit Timer/Counter1 can select clock source from CK, prescaled CK, or an external pin. In addition it can be stopped as described in section “Timer/Counter1 Control
Register B – TCCR1B” on page 45. The different Status Flags (Overflow, Compare
Match, and Capture Event) are found in the Timer/Counter Interrupt Flag Register –
TIFR. Control signals are found in the Timer/Counter1 Control Registers – TCCR1A and
TCCR1B. The interrupt enable/disable settings for Timer/Counter1 are found in the
Timer/Counter Interrupt Mask Register – TIMSK.
When Timer/Counter1 is externally clocked, the external signal is synchronized with the
Oscillator frequency of the CPU. To assure proper sampling of the external clock, the
minimum time between two external clock transitions must be at least one internal CPU
42
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
clock period. The external clock signal is sampled on the rising edge of the internal CPU
clock.
The 16-bit Timer/Counter1 features both a high resolution and a high accuracy usage
with the lower prescaling opportunities. Similarly, the high prescaling opportunities
makes the Timer/Counter1 useful for lower speed functions or exact timing functions
with infrequent actions.
The Timer/Counter1 supports two Output Compare functions using the Output Compare
Register 1 A and B (OCR1A and OCR1B) as the data sources to be compared to the
Timer/Counter1 contents. The Output Compare functions includes optional clearing of
the counter on Compare A Match, and actions on the Output Compare pins on both
compare matches.
Timer/Counter1 can also be used as an 8-, 9-, or 10-bit Pulse Width Modulator (PWM).
In this mode the counter and the OCR1A/OCR1B Registers serve as a dual glitch-free
stand-alone PWM with centered pulses. Alternatively, the Timer/Counter1 can be configured to operate at twice the speed in PWM mode, but without centered pulses. Refer
to page 48 for a detailed description of this function.
The Input Capture function of Timer/Counter1 provides a capture of the Timer/Counter1
contents to the Input Capture Register – ICR1, triggered by an external event on the
Input Capture Pin – ICP. The actual capture event settings are defined by the
Timer/Counter1 Control Register – TCCR1B. In addition, the Analog Comparator can be
set to trigger the Input Capture. Refer to the section, “The Analog Comparator” on page
102, for details on this. The ICP pin logic is shown in Figure 34.
Figure 34. ICP Pin Schematic Diagram
If the noise canceler function is enabled, the actual trigger condition for the capture
event is monitored over four samples, and all four must be equal to activate the Capture
Flag.
43
1142E–AVR–02/03
Timer/Counter1 Control
Register A – TCCR1A
Bit
7
6
5
4
3
2
1
0
COM1A1
COM1A0
COM1B1
COM1B0
FOC1A
FOC1B
PWM11
PWM10
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
$2F ($4F)
TCCR1A
• Bits 7, 6 – COM1A1, COM1A0: Compare Output Mode1A, Bits 1, and 0
The COM1A1 and COM1A0 control bits determine any output pin action following a
Compare Match in Timer/Counter1. Any output pin actions affect pin OC1A – Output
Compare A. This is an alternative function to an I/O Port, and the corresponding direction control bit must be set (one) to control an output pin. The control configuration is
shown in Table 10.
• Bits 5, 4 – COM1B1, COM1B0: Compare Output Mode1B, Bits 1, and 0
The COM1B1 and COM1B0 control bits determine any output pin action following a
Compare Match in Timer/Counter1. Any output pin actions affect pin OC1B – Output
Compare B. This is an alternative function to an I/O port, and the corresponding direction control bit must be set (one) to control an output pin. The control configuration is
shown in Table 10.
Table 12. Compare 1 Mode Select(1)
COM1X1
COM1X0
0
0
Timer/Counter1 disconnected from output pin OC1X
0
1
Toggle the OC1X output line.
1
0
Clear the OC1X output line (to zero).
1
1
Set the OC1X output line (to one).
Note:
Description
1. X = A or B.
In PWM mode, these bits have a different function. Refer to Table 14 for a detailed
description.
• Bit 3 – FOC1A: Force Output Compare1A
Writing a logical one to this bit, forces a change in the Compare Match Output pin PD5
according to the values already set in COM1A1 and COM1A0. If the COM1A1 and
COM1A0 bits are written in the same cycle as FOC1A, the new settings will not take
effect until next Compare Match or Forced Compare Match occurs. The Force Output
Compare bit can be used to change the output pin without waiting for a Compare Match
in the Timer. The automatic action programmed in COM1A1 and COM1A0 happens as if
a Compare Match had occurred, but no interrupt is generated and it will not clear the
timer even if CTC1 in TCCR1B is set. The corresponding I/O pin must be set as an output pin for the FOC1A bit to have effect on the pin. The FOC1A bit will always be read as
zero. The setting of the FOC1A bit has no effect in PWM mode.
• Bit 2 – FOC1B: Force Output Compare1B
Writing a logical one to this bit, forces a change in the Compare Match Output pin PD4
according to the values already set in COM1B1 and COM1B0. If the COM1B1 and
COM1B0 bits are written in the same cycle as FOC1B, the new settings will not take
effect until next Compare Match or Forced Compare Match occurs. The Force Output
Compare bit can be used to change the output pin without waiting for a Compare Match
44
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
in the Timer. The automatic action programmed in COM1B1 and COM1B0 happens as if
a Compare Match had occurred, but no interrupt is generated. The corresponding I/O
pin must be set as an output pin for the FOC1B bit to have effect on the pin. The FOC1B
bit will always be read as zero. The setting of the FOC1B bit has no effect in PWM
mode.
• Bits 1..0 – PWM11, PWM10: Pulse Width Modulator Select Bits
These bits select PWM operation of Timer/Counter1 as specified in Table 11. This mode
is described on page 48.
Table 13. PWM Mode Select
Timer/Counter1 Control
Register B – TCCR1B
PWM11
PWM10
0
0
PWM operation of Timer/Counter1 is disabled
0
1
Timer/Counter1 is an 8-bit PWM
1
0
Timer/Counter1 is a 9-bit PWM
1
1
Timer/Counter1 is a 10-bit PWM
Bit
Description
7
6
5
4
3
2
1
0
$2E ($4E)
ICNC1
ICES1
–
–
CTC1
CS12
CS11
CS10
Read/Write
R/W
R/W
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
TCCR1B
• Bit 7 – ICNC1: Input Capture1 Noise Canceler (4 CKs)
When the ICNC1 bit is cleared (zero), the Input Capture trigger noise canceler function
is disabled. The Input Capture is triggered at the first rising/falling edge sampled on the
ICP – Input Capture Pin – as specified. When the ICNC1 bit is set (one), four successive
samples are measures on the ICP – Input Capture Pin, and all samples must be
high/low according to the Input Capture trigger specification in the ICES1 bit. The actual
sampling frequency is XTAL clock frequency.
• Bit 6 – ICES1: Input Capture1 Edge Select
While the ICES1 bit is cleared (zero), the Timer/Counter1 contents are transferred to the
Input Capture Register – ICR1 – on the falling edge of the Input Capture Pin – ICP.
While the ICES1 bit is set (one), the Timer/Counter1 contents are transferred to the
Input Capture Register – ICR1 – on the rising edge of the Input Capture Pin – ICP.
• Bits 5, 4 – Res: Reserved Bits
These bits are reserved bits in the ATmega163 and always read as zero.
• Bit 3 – CTC1: Clear Timer/Counter1 on Compare Match
When the CTC1 control bit is set (one), the Timer/Counter1 is Reset to $0000 in the
clock cycle after a Compare A Match. If the CTC1 control bit is cleared, Timer/Counter1
continues counting and is unaffected by a Compare Match. When a prescaling of 1 is
used, and the Compare A Register is set to C, the timer will count as follows if CTC1 is
set:
... | C-1 | C | 0 | 1 |...
45
1142E–AVR–02/03
When the prescaler is set to divide by eight, the Timer will count like this:
... | C-1, C-1, C-1, C-1, C-1, C-1, C-1, C-1 | C, C, C, C, C, C, C, C | 0, 0, 0, 0, 0, 0, 0, 0
|1,1,1,1,1,1,1,1|...
In PWM mode, this bit has a different function. If the CTC1 bit is cleared in PWM mode,
the Timer/Counter1 acts as an up/down counter. If the CTC1 bit is set (one), the
Timer/Counter wraps when it reaches the TOP value. Refer to page 48 for a detailed
description.
• Bits 2..0 – CS12, CS11, CS10: Clock Select1, Bit 2, 1, and 0
The Clock Select1 bits 2, 1, and 0 define the prescaling source of Timer/Counter1.
Table 14. Clock 1 Prescale Select
CS12
CS11
CS10
Description
0
0
0
Stop, the Timer/Counter1 is stopped.
0
0
1
CK
0
1
0
CK/8
0
1
1
CK/64
1
0
0
CK/256
1
0
1
CK/1024
1
1
0
External Pin T1, falling edge
1
1
1
External Pin T1, rising edge
The Stop condition provides a Timer Enable/Disable function. The prescaled modes are
scaled directly from the CK Oscillator clock. If the external pin modes are used for
Timer/Counter1, transitions on PB1/(T1) will clock the counter even if the pin is configured as an output. This feature can give the user SW control of the counting.
Timer/Counter1 – TCNT1H
and TCNT1L
Bit
$2D ($4D)
15
14
13
12
11
10
9
TCNT1H
$2C ($4C)
LSB
7
Read/Write
Initial Value
8
MSB
6
5
4
3
2
1
TCNT1L
0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
This 16-bit register contains the prescaled value of the 16-bit Timer/Counter1. To
ensure that both the high and low bytes are read and written simultaneously when the
CPU accesses these registers, the access is performed using an 8-bit temporary register (TEMP). This temporary register is also used when accessing OCR1A, OCR1B, and
ICR1. If the main program and also interrupt routines perform access to registers using
TEMP, interrupts must be disabled during access from the main program and interrupt
routines.
46
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
TCNT1 Timer/Counter1 Write
When the CPU writes to the high byte TCNT1H, the written data is placed in the TEMP
Register. Next, when the CPU writes the low byte TCNT1L, this byte of data is combined
with the byte data in the TEMP Register, and all 16 bits are written to the TCNT1
Timer/Counter1 Register simultaneously. Consequently, the high byte TCNT1H must be
accessed first for a full 16-bit register write operation.
TCNT1 Timer/Counter1 Read
When the CPU reads the low byte TCNT1L, the data of the Low Byte TCNT1L is sent to
the CPU and the data of the High Byte TCNT1H is placed in the TEMP Register. When
the CPU reads the data in the High Byte TCNT1H, the CPU receives the data in the
TEMP Register. Consequently, the Low Byte TCNT1L must be accessed first for a full
16-bit register read operation.
The Timer/Counter1 is realized as an up or up/down (in PWM mode) counter with read
and write access. If Timer/Counter1 is written to and a clock source is selected, the
Timer/Counter1 continues counting in the timer clock cycle after it is preset with the written value.
Timer/Counter1 Output
Compare Register – OCR1AH
and OCR1AL
Bit
$2B ($4B)
15
14
13
12
11
10
9
OCR1AH
$2A ($4A)
LSB
7
Read/Write
Initial Value
Timer/Counter1 Output
Compare Register – OCR1BH
and OCR1BL
Bit
$29 ($49)
6
5
4
3
2
1
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
MSB
OCR1BH
LSB
7
Initial Value
OCR1AL
0
R/W
$28 ($48)
Read/Write
8
MSB
6
5
4
3
2
1
OCR1BL
0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
The Output Compare Registers are 16-bit read/write registers.
The Timer/Counter1 Output Compare Registers contain the data to be continuously
compared with Timer/Counter1. Actions on compare matches are specified in the
Timer/Counter1 Control and Status Register. A software write to the Timer/Counter
Register blocks compare matches in the next Timer/Counter clock cycle. This prevents
immediate interrupts when initializing the Timer/Counter.
A Compare Match will set the compare interrupt flag in the CPU clock cycle following the
compare event.
Since the Output Compare Registers – OCR1A and OCR1B – are 16-bit registers, a
temporary register TEMP is used when OCR1A/B are written to ensure that both bytes
are updated simultaneously. When the CPU writes the high byte, OCR1AH or OCR1BH,
the data is temporarily stored in the TEMP Register. When the CPU writes the Low Byte,
OCR1AL or OCR1BL, the TEMP Register is simultaneously written to OCR1AH or
OCR1BH. Consequently, the high byte OCR1AH or OCR1BH must be written first for a
full 16-bit register write operation.
47
1142E–AVR–02/03
The TEMP Register is also used when accessing TCNT1 and ICR1. If the main program
and also interrupt routines perform access to registers using TEMP, interrupts must be
disabled during access from the main program and interrupt routines.
Timer/Counter1 Input Capture
Register – ICR1H and ICR1L
Bit
$27 ($47)
15
14
13
12
11
10
9
ICR1H
$26 ($46)
Read/Write
Initial Value
8
MSB
LSB
7
6
5
4
3
2
1
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
ICR1L
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
The Input Capture Register is a 16-bit read-only register.
When the rising or falling edge (according to the input capture edge setting – ICES1) of
the signal at the Input Capture Pin – ICP – is detected, the current value of the
Timer/Counter1 Register – TCNT1 – is transferred to the Input Capture Register – ICR1.
At the same time, the Input Capture Flag – ICF1 – is set (one).
Since the Input Capture Register – ICR1 – is a 16-bit register, a temporary register
TEMP is used when ICR1 is read to ensure that both bytes are read simultaneously.
When the CPU reads the Low Byte ICR1L, the data is sent to the CPU and the data of
the High Byte ICR1H is placed in the TEMP Register. When the CPU reads the data in
the High Byte ICR1H, the CPU receives the data in the TEMP Register. Consequently,
the Low Byte ICR1L must be accessed first for a full 16-bit register read operation.
The TEMP Register is also used when accessing TCNT1, OCR1A, and OCR1B. If the
main program and also interrupt routines accesses registers using TEMP, interrupts
must be disabled during access from the main program and interrupt routines.
Timer/Counter1 in PWM Mode
When the PWM mode is selected, Timer/Counter1 and the Output Compare Register1A
– OCR1A and the Output Compare Register1B – OCR1B, form a dual 8,- 9-, or 10-bit,
free-running, glitch-free, and phase correct PWM with outputs on the PD5 (OC1A) and
PD4(OC1B) pins. In this mode, the Timer/Counter1 acts as an up/down counter, counting up from $0000 to TOP (see Table 16), where it turns and counts down again to zero
before the cycle is repeated. When the counter value matches the contents of the 8, 9,
or 10 least significant bits (depending on resolution) of OCR1A or OCR1B, the
PD5(OC1A)/PD4(OC1B) pins are set or cleared according to the settings of the
COM1A1/COM1A0 or COM1B1/COM1B0 bits in the Timer/Counter1 Control Register
TCCR1A. Refer to Table 12 on page 44 for details.
Alternatively, the Timer/Counter1 can be configured to a PWM that operates at twice the
speed as in the mode described above. Then the Timer/Counter1 and the Output Compare Register1A – OCR1A and the Output Compare Register1B – OCR1B, form a dual
8-, 9-, or 10-bit, free-running and glitch-free PWM with outputs on the PD5(OC1A) and
PD4(OC1B) pins.
48
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Table 15. Timer TOP Values and PWM Frequency
CTC1
PWM11
PWM10
PWM Resolution
Timer TOP Value
Frequency
0
0
1
8-bit
$00FF (255)
fTCK1/510
0
1
0
9-bit
$01FF (511)
fTCK1/1022
0
1
1
10-bit
$03FF(1023)
fTCK1/2046
1
0
1
8-bit
$00FF (255)
fTCK1/256
1
1
0
9-bit
$01FF (511)
fTCK1/512
1
1
1
10-bit
$03FF(1023)
fTCK1/1024
As shown in Table 15, the PWM operates at either 8, 9, or 10 bits resolution. Note the
unused bits in OCR1A, OCR1B, and TCNT1 will automatically be written to zero by
hardware. For example, bit 9 to 15 will be set to zero in OCR1A, OCR1B, and TCNT1 if
the 9-bit PWM resolution is selected. This makes it possible for the user to perform readmodify-write operations in any of the three resolution modes and the unused bits will be
treated as don’t care.
Table 16. Timer TOP Values and PWM Frequency
PWM Resolution
Timer TOP Value
Frequency
8-bit
$00FF (255)
fTC1/510
9-bit
$01FF (511)
fTC1/1022
10-bit
$03FF(1023)
fTC1/2046
Table 17. Compare1 Mode Select in PWM Mode(1)
CTC1
COM1X 1
COM1X 0
0
0
0
Not connected
0
0
1
Not connected
0
1
0
Cleared on Compare Match, up-counting. Set on Compare
Match, down-counting (non-inverted PWM).
0
1
1
Cleared on Compare Match, down-counting. Set on
Compare Match, up-counting (inverted PWM).
1
0
0
Not connected
1
0
1
Not connected
1
1
0
Cleared on Compare Match, set on overflow.
1
1
1
Set on Compare Match, cleared on overflow.
Note:
Effect on OCX1
1. X = A or B
Note that in the PWM mode, the 8, 9, or 10 least significant OCR1A/OCR1B bits
(depending on resolution), when written, are transferred to a temporary location. They
are latched when Timer/Counter1 reaches the value TOP. This prevents the occurrence
of odd-length PWM pulses (glitches) in the event of an unsynchronized OCR1A/OCR1B
write. See Figure 35 and Figure 36 for an example in each mode.
49
1142E–AVR–02/03
Figure 35. Effects of Unsynchronized OCR1 Latching.
PWM Output OC1x
Synchronized OC1x Latch
PWM Output OC1x
Unsynchronized OC1x Latch
Note: x = A or B
Figure 36. Effects of Unsynchronized OCR1 Latching in Overflow Mode.
PWM Output OC1x
Synchronized OC1x Latch
PWM Output OC1x
Unsynchronized OC1x Latch
Note: X = A or B
During the time between the write and the latch operation, a read from OCR1A or
OCR1B will read the contents of the temporary location. This means that the most
recently written value always will read out of OCR1A/B.
When the OCR1X contains $0000 or TOP, and the up/down PWM mode is selected, the
output OC1A/OC1B is updated to low or high on the next Compare Match according to
the settings of COM1A1/COM1A0 or COM1B1/COM1B0. This is shown in Table 18. In
overflow PWM mode, the output OC1A/OC1B is held low or high only when the Output
Compare Register contains TOP.
Table 18. PWM Outputs OCR1X = $0000 or TOP(1)
Note:
50
COM1X1
COM1X0
OCR1X
Output OC1X
1
0
$0000
L
1
0
TOP
H
1
1
$0000
H
1
1
TOP
L
1. X = A or B
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
In overflow PWM mode, the table above is only valid for OCR1X = TOP.
In PWM mode, the Timer Overflow Flag1, TOV1, is set when the counter advances from
$00 00. In overflow PWM mode, the Timer Overflow Flag is set as in Normal
Timer/Counter mode. Timer Overflow Interrupt1 operates exactly as in Normal
Timer/Counter mode, i.e., it is executed when TOV1 is set provided that Timer Overflow
Interrupt1 and global interrupts are enabled. This also applies to the Timer Output
Compare1 Flags and interrupts.
8-bit Timer/Counter 2
Figure 37 shows the block diagram for Timer/Counter2.
Figure 37. Timer/Counter2 Block Diagram
T/C2 OVER- T/C2 COMPARE
FLOW IRQ
MATCH IRQ
8-BIT DATA BUS
TOV2
0
TIMER/COUNTER2
(TCNT2)
CS20
CS21
CS22
CTC2
COM20
COM21
FOC2
T/C2 CONTROL
REGISTER (TCCR2)
T/C CLEAR
T/C CLK SOURCE
UP/DOWN
7
TOV0
TOV1
OCF1B
OCF1A
ICF1
OCF2
7
TOV2
TIMER INT. FLAG
REGISTER (TIFR)
TIMER INT. MASK
REGISTER (TIMSK)
PWM2
OCF2
TOIE0
TOIE1
OCIE1A
OCIE1B
TICIE1
TOIE2
OCIE2
8-BIT ASYNCH T/C2 DATA BUS
CK
PSR2
TOSC1
CONTROL
LOGIC
0
8-BIT COMPARATOR
0
OUTPUT COMPARE
REGISTER2 (OCR2)
CK
PCK2
ICR2UB
OCR2UB
AS2
ASYNCH. STATUS
REGISTER (ASSR)
TC2UB
7
SYNCH UNIT
The 8-bit Timer/Counter2 can select clock source from CK, prescaled CK, or external
crystal input TOSC1. It can also be stopped as described in the section “Timer/Counter2
Control Register – TCCR2” on page 52.
The Status Flags (Overflow and Compare Match) are found in the Timer/Counter Interrupt Flag Register – TIFR. Control signals are found in the Timer/Counter Control
Register TCCR2. The interrupt enable/disable settings are found in “The Timer/Counter
Interrupt Mask Register – TIMSK” on page 31.
When Timer/Counter2 is externally clocked, the external signal is synchronized with the
Oscillator frequency of the CPU. To assure proper sampling of the external clock, the
minimum time between two external clock transitions must be at least one internal CPU
51
1142E–AVR–02/03
clock period. The external clock signal is sampled on the rising edge of the internal CPU
clock.
This module features a high resolution and a high accuracy usage with the lower prescaling opportunities. Similarly, the high prescaling opportunities make this unit useful for
lower speed functions or exact timing functions with infrequent actions.
Timer/Counter2 can also be used as an 8-bit Pulse Width Modulator. In this mode,
Timer/Counter2 and the Output Compare Register serve as a glitch-free, stand-alone
PWM with centered pulses. Refer to page 57 for a detailed description on this function.
Timer/Counter2 Control
Register – TCCR2
Bit
7
6
5
4
3
2
1
0
FOC2
PWM2
COM21
COM20
CTC2
CS22
CS21
CS20
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
$25 ($45)
TCCR2
• Bit 7 – FOC2: Force Output Compare
Writing a logical one to this bit, forces a change in the Compare Match output pin PD7
(OC2) according to the values already set in COM21 and COM20. If the COM21 and
COM20 bits are written in the same cycle as FOC2, the new settings will not take effect
until next compare match or Forced Output Compare Match occurs. The Force Output
Compare bit can be used to change the output pin without waiting for a Compare Match
in the Timer. The automatic action programmed in COM21 and COM20 happens as if a
Compare Match had occurred, but no interrupt is generated, and the Timer/Counter will
not be cleared even if CTC2 is set. The corresponding I/O pin must be set as an output
pin for the FOC2 bit to have effect on the pin. The FOC2 bit will always be read as zero.
Setting the FOC2 bit has no effect in PWM mode.
• Bit 6 – PWM2: Pulse Width Modulator Enable
When set (one) this bit enables PWM mode for Timer/Counter2. This mode is described
on page 43.
• Bits 5, 4 – COM21, COM20: Compare Output Mode, Bits 1 and 0
The COM21 and COM20 control bits determine any output pin action following a Compare Match in Timer/Counter2. Output pin actions affect pin PD7(OC2). This is an
alternative function to an I/O port, and the corresponding direction control bit must be
set (one) to control an output pin. The control configuration is shown in Table 19.
Table 19. Compare Mode Select(1)
COM21
COM20
0
0
Timer/Counter disconnected from output pin OC2
0
1
Toggle the OC2 output line.
1
0
Clear the OC2 output line (to zero).
1
1
Set the OC2 output line (to one).
Note:
52
Description
1. In PWM mode, these bits have a different function. Refer to Table 21 on page 55 for
a detailed description.
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
• Bit 3 – CTC2: Clear Timer/Counter on Compare Match
When the CTC2 control bit is set (one), Timer/Counter2 is Reset to $00 in the CPU clock
cycle following a Compare Match. If the control bit is cleared, the Timer/Counter2 continues counting and is unaffected by a Compare Match. When a prescaling of 1 is used,
and the Compare Register is set to C, the Timer will count as follows if CTC2 is set:
... | C-1 | C | 0 | 1 |...
When the prescaler is set to divide by eight, the Timer will count like this:
... | C-1, C-1, C-1, C-1, C-1, C-1, C-1, C-1 | C, C, C, C, C, C, C, C | 0, 0, 0, 0, 0, 0, 0, 0 |
1, 1, 1, ...
In PWM mode, this bit has a different function. If the CTC2 bit is cleared in PWM mode,
the Timer/Counter acts as an up/down counter. If the CTC2 bit is set (one), the
Timer/Counter wraps when it reaches $FF. Refer to page 54 for a detailed description.
• Bits 2, 1, 0 – CS22, CS21, CS20: Clock Select Bits 2, 1, and 0
The Clock Select bits 2, 1, and 0 define the prescaling source of Timer/Counter2.
Table 20. Timer/Counter2 Prescale Select
CS22
CS21
CS20
Description
0
0
0
Timer/Counter2 is stopped.
0
0
1
PCK2
0
1
0
PCK2/8
0
1
1
PCK2/32
1
0
0
PCK2/64
1
0
1
PCK2/128
1
1
0
PCK2/256
1
1
1
PCK2/1024
The Stop condition provides a Timer Enable/Disable function. The prescaled modes are
scaled directly from the PCK2 clock.
Timer/Counter2 – TCNT2
Bit
7
6
5
4
3
2
1
0
$24 ($44)
MSB
LSB
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
TCNT2
This 8-bit register contains the value of Timer/Counter2.
Timer/Counters2 is implemented as an up or up/down (in PWM mode) counter with read
and write access. If the Timer/Counter2 is written to and a clock source is selected, it
continues counting in the timer clock cycle following the write operation.
53
1142E–AVR–02/03
Timer/Counter2 Output
Compare Register – OCR2
Bit
7
6
5
4
3
2
1
0
$23 ($43)
MSB
LSB
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
OCR2
The Output Compare Register is an 8-bit read/write register.
The Timer/Counter Output Compare Register contains the data to be continuously compared with Timer/Counter2. Actions on compare matches are specified in TCCR2. A
software write to the Timer/Counter2 Register blocks compare matches in the next
Timer/Counter2 clock cycle. This prevents immediate interrupts when initializing the
Timer/Counter2.
A Compare Match will set the Compare Interrupt Flag in the CPU clock cycle following
the compare event.
Timer/Counter2 in PWM Mode
When PWM mode is selected, the Timer/Counter2 either wraps (overflows) when it
reaches $FF or it acts as an up/down counter.
If the up/down mode is selected, the Timer/Counter2 and the Output Compare Register
– OCR2 form an 8-bit, free-running, glitch-free, and phase correct PWM with outputs on
the PD7(OC2) pin.
If the overflow mode is selected, the Timer/Counter2 and the Output Compare Register
– OCR2 form an 8-bit, free-running, and glitch-free PWM, operating with twice the speed
of the up/down counting mode.
PWM Modes (Up/Down and
Overflow)
The two different PWM modes are selected by the CTC2 bit in the Timer/Counter Control Register – TCCR2.
If CTC2 is cleared and PWM mode is selected, the Timer/Counter acts as an up/down
counter, counting up from $00 to $FF, where it turns and counts down again to zero
before the cycle is repeated. When the counter value matches the contents of the Output Compare Register, the PD7(OC2) pin is set or cleared according to the settings of
the COM21/COM20 bits in the Timer/Counter Control Register TCCR2.
If CTC2 is set and PWM mode is selected, the Timer/Counters will wrap and start counting from $00 after reaching $FF. The PD7(OC2) pin will be set or cleared according to
the settings of COM21/COM20 on a Timer/Counter overflow or when the counter value
matches the contents of the Output Compare Register. Refer to Table 21 for details.
54
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Table 21. Compare Mode Select in PWM Mode
CTC2
COM21
COM20
Effect on Compare Pin
Frequency
0
0
0
Not connected
0
0
1
Not connected
0
1
0
Cleared on Compare Match, up-counting. Set on
Compare Match, down-counting (non-inverted
PWM).
fTCK0/2/510
0
1
1
Cleared on Compare Match, down-counting. Set
on Compare Match, up-counting (inverted PWM).
fTCK0/2/510
1
0
0
Not connected
1
0
1
Not connected
1
1
0
Cleared on compare match, set on overflow.
fTCK0/2/256
1
1
1
Set on compare match, cleared on overflow.
fTCK0/2/256
Note that in PWM mode, the value to be written to the Output Compare Register is first
tr an sfe rr ed to a temp o ra ry lo ca tio n , an d the n latc he d in to O CR 2 w h en th e
Timer/Counter reaches $FF. This prevents the occurrence of odd-length PWM pulses
(glitches) in the event of an unsynchronized OCR2 write. See Figure 38 for examples.
Figure 38. Effects of Unsynchronized OCR Latching
PWM Output OC2
Synchronized OC2 Latch
PWM Output OC2
Unsynchronized OC2 Latch
55
1142E–AVR–02/03
Figure 39. Effects of Unsynchronized OCR Latching in Overflow Mode.
Compare Value changes
Counter Value
Compare Value
PWM Output OC2
Synchronized OC2 Latch
Compare Value changes
Counter Value
Compare Value
PWM Output OC2
Unsynchronized OC2 Latch
Glitch
During the time between the write and the latch operation, a read from OCR2 will read
the contents of the temporary location. This means that the most recently written value
always will read out of OCR2.
When the Output Compare Register contains $00 or $FF, and the up/down PWM mode
is selected, the output PD7(OC2) is updated to low or high on the next compare match
according to the settings of COM21/COM20. This is shown in Table 22. In overflow
PWM mode, the output PD7(OC2) is held low or high only when the Output Compare
Register contains $FF.
Table 22. PWM Outputs OCR2 = $00 or $FF
COM21
COM20
OCR2
Output OC2
1
0
$00
L
1
0
$FF
H
1
1
$00
H
1
1
$FF
L
In up/down PWM mode, the Timer Overflow Flag – TOV2, is set when the counter
changes direction at $00. In overflow PWM mode, the Timer Overflow Flag is set as in
normal Timer/Counter mode. The Timer Overflow Interrupt operates exactly as in normal Timer/Counter mode, i.e., it is executed when TOV2 is set provided that Timer
Overflow Interrupt and Global Interrupts are enabled. This also applies to the Timer Output Compare Flag and Interrupt.
The frequency of the PWM will be Timer Clock Frequency divided by 510.
56
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Asynchronous Status
Register – ASSR
Bit
7
6
5
4
3
2
1
0
$22 ($22)
–
–
–
–
AS2
TCN2UB
OCR2UB
TCR2UB
Read/Write
R
R
R
R
R/W
R
R
R
Initial Value
0
0
0
0
0
0
0
0
ASSR
• Bit 7..4 – Res: Reserved Bits
These bits are reserved bits in the ATmega163 and always read as zero.
• Bit 3 – AS2: Asynchronous Timer/Counter2
When AS2 is cleared (zero), Timer/Counter2 is clocked from the internal system clock,
CK. When AS2 is set (one), Timer/Counter2 is clocked from the PC6(TOSC1) pin. Pins
PC6 and PC7 are connected to a crystal Oscillator and cannot be used as general I/O
pins. When the value of this bit is changed, the contents of TCNT2, OCR2, and TCCR2
might be corrupted.
• Bit 2 – TCN2UB: Timer/Counter2 Update Busy
When Timer/Counter2 operates asynchronously and TCNT2 is written, this bit becomes
set (one). When TCNT2 has been updated from the temporary storage register, this bit
is cleared (zero) by hardware. A logical zero in this bit indicates that TCNT2 is ready to
be updated with a new value.
• Bit 1 – OCR2UB: Output Compare Register2 Update Busy
When Timer/Counter2 operates asynchronously and OCR2 is written, this bit becomes
set (one). When OCR2 has been updated from the temporary storage register, this bit is
cleared (zero) by hardware. A logical zero in this bit indicates that OCR2 is ready to be
updated with a new value.
• Bit 0 – TCR2UB: Timer/Counter Control Register2 Update Busy
When Timer/Counter2 operates asynchronously and TCCR2 is written, this bit becomes
set (one). When TCCR2 has been updated from the temporary storage register, this bit
is cleared (zero) by hardware. A logical zero in this bit indicates that TCCR2 is ready to
be updated with a new value.
If a write is performed to any of the three Timer/Counter2 Registers while its update
busy flag is set (one), the updated value might get corrupted and cause an unintentional
interrupt to occur.
The mechanisms for reading TCNT2, OCR2, and TCCR2 are different. When reading
TCNT2, the actual timer value is read. When reading OCR2 or TCCR2, the value in the
temporary storage register is read.
57
1142E–AVR–02/03
Asynchronous Operation of
Timer/Counter2
When Timer/Counter2 operates asynchronously, some considerations must be taken.
•
Warning: When switching between asynchronous and synchronous clocking of
Timer/Counter2, the Timer Registers TCNT2, OCR2, and TCCR2 might be
corrupted. A safe procedure for switching clock source is:
1. Disable the Timer/Counter2 interrupts by clearing OCIE2 and TOIE2.
2. Select clock source by setting AS2 as appropriate.
3. Write new values to TCNT2, OCR2, and TCCR2.
4. To switch to asynchronous operation: Wait for TCN2UB, OCR2UB, and
TCR2UB.
5. Clear the Timer/Counter2 Interrupt Flags.
6. Enable interrupts, if needed.
•
The Oscillator is optimized for use with a 32.768 kHz watch crystal. Applying an
external clock to the TOSC1 pin may result in incorrect Timer/Counter2 operation.
The CPU main clock frequency must be more than four times the Oscillator
frequency.
•
When writing to one of the registers TCNT2, OCR2, or TCCR2, the value is
transferred to a temporary register, and latched after two positive edges on TOSC1.
The user should not write a new value before the contents of the temporary register
have been transferred to its destination. Each of the three mentioned registers have
their individual temporary register, which means that e.g. writing to TCNT2 does not
disturb an OCR2 write in progress. To detect that a transfer to the destination
register has taken place, the Asynchronous Status Register – ASSR has been
implemented.
•
When entering Power-save mode after having written to TCNT2, OCR2, or TCCR2,
the user must wait until the written register has been updated if Timer/Counter2 is
used to wake up the device. Otherwise, the MCU will enter sleep mode before the
changes are effective. This is particularly important if the Output Compare2 interrupt
is used to wake up the device, since the output compare function is disabled during
writing to OCR2 or TCNT2. If the write cycle is not finished, and the MCU enters
sleep mode before the OCR2UB bit returns to zero, the device will never receive a
compare match interrupt, and the MCU will not wake up.
•
If Timer/Counter2 is used to wake the device up from Power-save mode,
precautions must be taken if the user wants to re-enter Power-save mode: The
interrupt logic needs one TOSC1 cycle to be Reset. If the time between wake-up
and re-entering Power-save mode is less than one TOSC1 cycle, the interrupt will
not occur, and the device will fail to wake up. If the user is in doubt whether the time
before re-entering Power-save is sufficient, the following algorithm can be used to
ensure that one TOSC1 cycle has elapsed:
1. Write a value to TCCR2, TCNT2, or OCR2.
2. Wait until the corresponding Update Busy Flag in ASSR returns to zero.
3. Enter Power-save mode.
58
•
When the asynchronous operation is selected, the 32.768 kHz Oscillator for
Timer/Counter2 is always running, except in Power-down mode. After a Power-up
Reset or Wake-up from Power-down, the user should be aware of the fact that this
Oscillator might take as long as one second to stabilize. The user is advised to wait
for at least one second before using Timer/Counter2 after Power-up or wake-up
from Power-down. The contents of all Timer/Counter2 Registers must be considered
lost after a wake-up from Power-down due to unstable clock signal upon startup.
•
Description of wake-up from Power-save mode when the Timer is clocked
asynchronously: When the interrupt condition is met, the wake-up process is started
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
on the following cycle of the timer clock, that is, the timer is always advanced by at
least one before the processor can read the counter value. After wake-up, the MCU
is halted for four clock cycles, it executes the interrupt routine, and resumes
execution from the instruction following SLEEP.
•
During asynchronous operation, the synchronization of the interrupt flags for the
asynchronous timer takes three processor cycles plus one timer cycle. The timer is
therefore advanced by at least one before the processor can read the timer value
causing the setting of the Interrupt Flag. The output compare pin is changed on the
timer clock and is not synchronized to the processor clock.
•
After waking up from Power-save mode with the asynchronous timer enabled, there
will be a short interval in which TCNT2 will read as the same value as before Powersave mode was entered. After an edge on the asynchronous clock, TCNT2 will read
correctly (The compare and overflow functions of the Timer are not affected by this
behavior.). Safe procedure to ensure that the correct value is read:
1. Write any value to either of the registers OCR2 or TCCR2.
2. Wait for the corresponding Update Busy Flag to be cleared.
3. Read TCNT2.
Note that OCR2 and TCCR2 are never modified by hardware, and will always read
correctly.
59
1142E–AVR–02/03
Watchdog Timer
The Watchdog Timer is clocked from a separate On-chip Oscillator which runs at
1 MHz. This is the typical value at VCC = 5V. See characterization data for typical values
at other VCC levels. By controlling the Watchdog Timer prescaler, the Watchdog Reset
interval can be adjusted as shown in Table 23 on page 61. The WDR – Watchdog Reset
– instruction resets the Watchdog Timer. Eight different clock cycle periods can be
selected to determine the reset period. If the reset period expires without another
Watchdog Reset, the ATmega163 resets and executes from the Reset Vector. For timing details on the Watchdog Reset, refer to page 28.
To prevent unintentional disabling of the Watchdog, a special turn-off sequence must be
followed when the Watchdog is disabled. Refer to the description of the Watchdog Timer
Control Register for details.
Figure 40. Watchdog Timer
OSCILLATOR
1 MHz at VCC = 5V
The Watchdog Timer Control
Register – WDTCR
Bit
7
6
5
4
3
2
1
0
$21 ($41)
–
–
–
WDTOE
WDE
WDP2
WDP1
WDP0
Read/Write
R
R
R
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
WDTCR
• Bits 7..5 – Res: Reserved Bits
These bits are reserved bits in the ATmega163 and will always read as zero.
• Bit 4 – WDTOE: Watchdog Turn-off Enable
This bit must be set (one) when the WDE bit is cleared. Otherwise, the Watchdog will
not be disabled. Once set, hardware will clear this bit to zero after four clock cycles.
Refer to the description of the WDE bit for a Watchdog disable procedure.
• Bit 3 – WDE: Watchdog Enable
When the WDE is set (one) the Watchdog Timer is enabled, and if the WDE is cleared
(zero) the Watchdog Timer function is disabled. WDE can only be cleared if the WDTOE
bit is set(one). To disable an enabled Watchdog Timer, the following procedure must be
followed:
60
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
1. In the same operation, write a logical one to WDTOE and WDE. A logical one
must be written to WDE even though it is set to one before the disable operation
starts.
2. Within the next four clock cycles, write a logical 0 to WDE. This disables the
Watchdog.
• Bits 2..0 – WDP2, WDP1, WDP0: Watchdog Timer Prescaler 2, 1, and 0
The WDP2, WDP1, and WDP0 bits determine the Watchdog Timer prescaling when the
Watchdog Timer is enabled. The different prescaling values and their corresponding
Timeout Periods are shown in Table 23.
Table 23. Watchdog Timer Prescale Select
WDP2
WDP1
WDP0
Number of WDT
Oscillator Cycles
Typical Time-out
at VCC = 3.0V
Typical Time-out
at VCC = 5.0V
0
0
0
16K cycles
47 ms
15 ms
0
0
1
32K cycles
94 ms
30 ms
0
1
0
64K cycles
0.19 s
60 ms
0
1
1
128K cycles
0.38 s
0.12 s
1
0
0
256K cycles
0.75 s
0.24 s
1
0
1
512K cycles
1.5 s
0.49 s
1
1
0
1,024K cycles
3.0 s
0.97 s
1
1
1
2,048K cycles
6.0 s
1.9 s
61
1142E–AVR–02/03
EEPROM Read/Write
Access
The EEPROM Access Registers are accessible in the I/O space.
The write access time is in the range of 1.9 - 3.8 ms, depending on the VCC voltages.
See Table 24 for details. A self-timing function, however, lets the user software detect
when the next byte can be written. If the user code contains code that writes the
EEPROM, some precautions must be taken. In heavily filtered power supplies, VCC is
likely to rise or fall slowly on Power-up/down. This causes the device for some period of
time to run at a voltage lower than specified as minimum for the clock frequency used.
CPU operation under these conditions is likely to cause the Program Counter to perform
unintentional jumps and potentially execute the EEPROM write code. To secure
EEPROM integrity, the user is advised to use an External under-voltage Reset circuit or
the internal BOD in this case.
In order to prevent unintentional EEPROM writes, a specific write procedure must be followed. Refer to the description of the EEPROM Control Register for details on this.
When the EEPROM is read, the CPU is halted for four clock cycles before the next
instruction is executed. When the EEPROM is written, the CPU is halted for two clock
cycles before the next instruction is executed.
The EEPROM Address
Register – EEARH and EEARL
Bit
15
14
13
12
11
10
9
8
$1F ($3F)
–
–
–
–
–
–
–
EEAR8
EEARH
$1E ($3E)
EEAR7
EEAR6
EEAR5
EEAR4
EEAR3
EEAR2
EEAR1
EEAR0
EEARL
7
6
5
4
3
2
1
0
Read/Write
Initial Value
R
R
R
R
R
R
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
X
X
X
X
X
X
X
X
X
• Bits 15..9 – Res: Reserved Bits
These bits are reserved bits in the ATmega163 and will always read as zero.
• Bits 8..0 – EEAR8..0: EEPROM Address
The EEPROM Address Registers – EEARH and EEARL – specify the EEPROM
address in the 512 bytes EEPROM space. The EEPROM data bytes are addressed linearly between 0 and 511. The initial value of EEAR is undefined. A proper value must be
written before the EEPROM may be accessed.
The EEPROM Data Register –
EEDR
Bit
7
6
5
4
3
2
1
0
$1D ($3D)
MSB
LSB
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
EEDR
• Bits 7..0 – EEDR7.0: EEPROM Data
For the EEPROM write operation, the EEDR Register contains the data to be written to
the EEPROM in the address given by the EEAR Register. For the EEPROM read operation, the EEDR contains the data read out from the EEPROM at the address given by
EEAR.
62
ATmega163(L)
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ATmega163(L)
The EEPROM Control Register
– EECR
Bit
7
6
5
4
3
2
1
0
$1C ($3C)
–
–
–
–
EERIE
EEMWE
EEWE
EERE
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
EECR
• Bits 7..4 – Res: Reserved Bits
These bits are reserved bits in the ATmega163 and will always read as zero.
• Bit 3 – EERIE: EEPROM Ready Interrupt Enable
When the I bit in SREG and EERIE are set (one), the EEPROM Ready Interrupt is
enabled. When cleared (zero), the interrupt is disabled. The EEPROM Ready interrupt
generates a constant interrupt when EEWE is cleared (zero).
• Bit 2 – EEMWE: EEPROM Master Write Enable
The EEMWE bit determines whether setting EEWE to one causes the EEPROM to be
written. When EEMWE is set(one) setting EEWE will write data to the EEPROM at the
selected address If EEMWE is zero, setting EEWE will have no effect. When EEMWE
has been set (one) by software, hardware clears the bit to zero after four clock cycles.
See the description of the EEWE bit for an EEPROM write procedure.
• Bit 1 – EEWE: EEPROM Write Enable
The EEPROM Write Enable Signal EEWE is the write strobe to the EEPROM. When
address and data are correctly set up, the EEWE bit must be set to write the value into
the EEPROM. The EEMWE bit must be set when the logical one is written to EEWE,
otherwise no EEPROM write takes place. The following procedure should be followed
when writing the EEPROM (the order of steps 2 and 3 is not essential):
1. Wait until EEWE becomes zero.
2. Write new EEPROM address to EEAR (optional).
3. Write new EEPROM data to EEDR (optional).
4. Write a logical one to the EEMWE bit in EECR.
5. Within four clock cycles after setting EEMWE, write a logical one to EEWE.
Caution: An interrupt between step 4 and step 5 will make the write cycle fail, since the
EEPROM Master Write Enable will time-out. If an interrupt routine accessing the
EEPROM is interrupting another EEPROM access, the EEAR or EEDR Register will be
modified, causing the interrupted EEPROM access to fail. It is recommended to have
the Global Interrupt Flag cleared during the four last steps to avoid these problems.
When the write access time (see Table 24) has elapsed, the EEWE bit is cleared (zero)
by hardware. The user software can poll this bit and wait for a zero before writing the
next byte. When EEWE has been set, the CPU is halted for four cycles before the next
instruction is executed.
• Bit 0 – EERE: EEPROM Read Enable
The EEPROM Read Enable Signal EERE is the read strobe to the EEPROM. When the
correct address is set up in the EEAR Register, the EERE bit must be set. When the
EERE bit is cleared (zero) by hardware, requested data is found in the EEDR Register.
The EEPROM read access takes one instruction, and there is no need to poll the EERE
bit. When EERE has been set, the CPU is halted for two cycles before the next instruction is executed.
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1142E–AVR–02/03
The user should poll the EEWE bit before starting the read operation. If a write operation
is in progress, it is not possible to set the EERE bit, nor to change the EEAR Register.
The calibrated Oscillator is used to time the EEPROM accesses. Table 24 lists the typical programming time for EEPROM access from the CPU
Table 24. EEPROM Programming Time.
Symbol
EEPROM write
(from CPU)
Preventing EEPROM
Corruption
Number of Calibrated
RC Oscillator Cycles
Min Programmingn
Time
Max Programming
Time
2048
1.9 ms
3.8 ms
During periods of low VCC, the EEPROM data can be corrupted because the supply voltage is too low for the CPU and the EEPROM to operate properly. These issues are the
same as for board level systems using the EEPROM, and the same design solutions
should be applied.
An EEPROM data corruption can be caused by two situations when the voltage is too
low. First, a regular write sequence to the EEPROM requires a minimum voltage to
operate correctly. Secondly, the CPU itself can execute instructions incorrectly, if the
supply voltage for executing instructions is too low.
EEPROM data corruption can easily be avoided by following these design recommendations (one is sufficient):
1. Keep the AVR RESET active (low) during periods of insufficient power supply
voltage. This can be done by enabling the internal Brown-out Detector (BOD) if
the operating voltage matches the detection level. If not, an external low VCC
Reset Protection circuit can be used. If a Reset occurs while a write operation is
in progress, the write operation will be completed provided that the power supply
is voltage is sufficient.
2. Keep the AVR core in Power-down Sleep Mode during periods of low VCC. This
will prevent the CPU from attempting to decode and execute instructions, effectively protecting the EEPROM Registers from unintentional writes.
3. Store constants in Flash memory if the ability to change memory contents from
software is not required. Flash memory can not be updated by the CPU unless
the boot loader software supports writing to the Flash and the Boot Lock bits are
configured so that writing to the Flash memory from CPU is allowed. See “Boot
Loader Support” on page 134 for details.
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ATmega163(L)
Serial Peripheral
Interface – SPI
The Serial Peripheral Interface (SPI) allows high-speed synchronous data transfer
between the ATmega163 and peripheral devices or between several AVR devices. The
ATmega163 SPI includes the following features:
• Full-duplex, Three-wire Synchronous Data Transfer
• Master or Slave Operation
• LSB First or MSB First Data Transfer
• Seven Programmable Bit Rates
• End of Transmission Interrupt Flag
• Write Collision Flag Protection
• Wake-up from Idle Mode
• Double Speed (CK/2) Master SPI Mode
Figure 41. SPI Block Diagram
SPI2X
SPI2X
DIVIDER
/2/4/8/16/32/64/128
The interconnection between Master and Slave CPUs with SPI is shown in Figure 42.
The PB7(SCK) pin is the clock output in the Master mode and the clock input in the
Slave mode. Writing to the SPI Data Register of the Master CPU starts the SPI clock
generator, and the data written shifts out of the PB5(MOSI) pin and into the PB5(MOSI)
pin of the Slave CPU. After shifting one byte, the SPI Clock Generator stops, setting the
end of Transmission Flag (SPIF). If the SPI Interrupt Enable bit (SPIE) in the SPCR
Register is set, an interrupt is requested. The Slave Select input, PB4(SS), is set low to
select an individual Slave SPI device. The two Shift Registers in the Master and the
Slave can be considered as one distributed 16-bit circular Shift Register. This is shown
in Figure 42. When data is shifted from the Master to the Slave, data is also shifted in
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1142E–AVR–02/03
the opposite direction, simultaneously. During one shift cycle, data in the Master and the
Slave is interchanged.
Figure 42. SPI Master-Slave Interconnection
The system is single buffered in the transmit direction and double buffered in the receive
direction. This means that bytes to be transmitted cannot be written to the SPI Data
Register before the entire shift cycle is completed. When receiving data, however, a
received character must be read from the SPI Data Register before the next character
has been completely shifted in. Otherwise, the first byte is lost.
When the SPI is enabled, the data direction of the MOSI, MISO, SCK, and SS pins is
overridden according to Table 25.
Table 25. SPI Pin Overrides(1)
Pin
Direction, Master SPI
Direction, Slave SPI
MOSI
User Defined
Input
MISO
Input
User Defined
SCK
User Defined
Input
SS
User Defined
Input
Note:
SS Pin Functionality
1. See “Alternate Functions Of PORTB” on page 118 for a detailed description of how to
define the direction of the user defined SPI pins.
When the SPI is configured as a Master (MSTR in SPCR is set), the user can determine
the direction of the SS pin. If SS is configured as an output, the pin is a general output
pin which does not affect the SPI system. If SS is configured as an input, it must be held
high to ensure Master SPI operation. If the SS pin is driven low by peripheral circuitry
when the SPI is configured as a Master with the SS pin defined as an input, the SPI system interprets this as another Master selecting the SPI as a Slave and starting to send
data to it. To avoid bus contention, the SPI system takes the following actions:
1. The MSTR bit in SPCR is cleared and the SPI system becomes a Slave. As a
result of the SPI becoming a Slave, the MOSI and SCK pins become inputs.
2. The SPIF Flag in SPSR is set, and if the SPI interrupt is enabled, and the I-bit in
SREG is set, the interrupt routine will be executed.
Thus, when interrupt-driven SPI transmission is used in Master mode, and there exists a
possibility that SS is driven low, the interrupt should always check that the MSTR bit is
still set. If the MSTR bit has been cleared by a slave select, it must be set by the user to
re-enable SPI Master mode.
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ATmega163(L)
When the SPI is configured as a Slave, the SS pin is always input. When SS is held low,
the SPI is activated, and MISO becomes an output if configured so by the user. All other
pins are inputs. When SS is driven high, all pins are inputs, and the SPI is passive,
which means that it will not receive incoming data. Note that the SPI logic will be Reset
once the SS pin is driven high. If the SS pin is driven high during a transmission, the SPI
will stop sending and receiving immediately and both data received and data sent must
be considered as lost.
Data Modes
There are four combinations of SCK phase and polarity with respect to serial data,
which are determined by control bits CPHA and CPOL. The SPI data transfer formats
are shown in Figure 43 and Figure 44.
Figure 43. SPI Transfer Format with CPHA = 0 and DORD = 0
Figure 44. SPI Transfer Format with CPHA = 1 and DORD = 0
SPI Control Register – SPCR
Bit
7
6
5
4
3
2
1
0
$0D ($2D)
SPIE
SPE
DORD
MSTR
CPOL
CPHA
SPR1
SPR0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
SPCR
• Bit 7 – SPIE: SPI Interrupt Enable
This bit causes the SPI interrupt to be executed if SPIF bit in the SPSR Register is set
and the if the Global Interrupt Enable bit in SREG is set.
• Bit 6 – SPE: SPI Enable
When the SPE bit is set (one), the SPI is enabled. This bit must be set to enable any SPI
operations.
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• Bit 5 – DORD: Data Order
When the DORD bit is set (one), the LSB of the data word is transmitted first.
When the DORD bit is cleared (zero), the MSB of the data word is transmitted first.
• Bit 4 – MSTR: Master/Slave Select
This bit selects Master SPI mode when set (one), and Slave SPI mode when cleared
(zero). If SS is configured as an input and is driven low while MSTR is set, MSTR will be
cleared, and SPIF in SPSR will become set. The user will then have to set MSTR to reenable SPI Master mode.
• Bit 3 – CPOL: Clock Polarity
When this bit is set (one), SCK is high when idle. When CPOL is cleared (zero), SCK is
low when idle. Refer to Figure 43 and Figure 44 for additional information.
• Bit 2 – CPHA: Clock Phase
Refer to Figure 43 and Figure 44 for the functionality of this bit.
• Bits 1, 0 – SPR1, SPR0: SPI Clock Rate Select 1 and 0
These two bits control the SCK rate of the device configured as a Master. SPR1 and
SPR0 have no effect on the Slave. The relationship between SCK and the Oscillator
Clock frequency fck is shown in the following table:
Table 26. Relationship Between SCK and the Oscillator Frequency
The SPI Status Register –
SPSR
SPI2X
SPR1
SPR0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Bit
SCK Frequency
fck/4
fck/16
fck/64
fck/128
fck/2
fck/8
fck/32
fck/64
7
6
5
4
3
2
1
0
$0E ($2E)
SPIF
WCOL
–
–
–
–
–
SPI2X
Read/Write
R
R
R
R
R
R
R
R/W
Initial Value
0
0
0
0
0
0
0
0
SPSR
• Bit 7 – SPIF : SPI Interrupt Flag
When a serial transfer is complete, the SPIF bit is set (one) and an interrupt is generated if SPIE in SPCR is set (one) and global interrupts are enabled. If SS is an input and
is driven low when the SPI is in Master mode, this will also set the SPIF Flag. SPIF is
cleared by hardware when executing the corresponding Interrupt Handling Vector. Alternatively, the SPIF bit is cleared by first reading the SPI Status Register with SPIF set
(one), then accessing the SPI Data Register (SPDR).
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ATmega163(L)
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ATmega163(L)
• Bit 6 – WCOL : Write COLlision Flag
The WCOL bit is set if the SPI Data Register (SPDR) is written during a data transfer.
The WCOL bit (and the SPIF bit) are cleared (zero) by first reading the SPI Status Register with WCOL set (one), and then accessing the SPI Data Register.
• Bit 5..1 – Res: Reserved Bits
These bits are reserved bits in the ATmega163 and will always read as zero.
• Bit 0 – SPI2X: Double SPI Speed Bit
When this bit is set (one) the SPI speed (SCK Frequency) will be doubled when the SPI
is in Master mode (see Table 26). This means that the minimum SCK period will be two
CPU clock periods. When the SPI is configured as Slave, the SPI is only guaranteed to
work at fck/4 or lower.
The SPI interface on the ATmega163 is also used for Program memory and EEPROM
downloading or uploading. See page 155 for Serial Programming and verification.
The SPI Data Register – SPDR
Bit
7
6
5
4
3
2
1
0
$0F ($2F)
MSB
LSB
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
X
X
X
X
X
X
X
X
SPDR
Undefined
The SPI Data Register is a read/write register used for data transfer between the Register File and the SPI Shift Register. Writing to the register initiates data transmission.
Reading the register causes the Shift Register Receive buffer to be read.
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UART
The ATmega163 features a full duplex (separate Receive and Transmit Registers) Universal Asynchronous Receiver and Transmitter (UART). The main features are:
• Baud Rate Generator Generates any Baud Rate
• High Baud Rates at Low XTAL Frequencies
• 8 or 9 Bits Data
• Noise Filtering
• OverRun Detection
• Framing Error Detection
• False Start Bit Detection
• Three Separate Interrupts on TX Complete, TX Data Register Empty, and RX Complete
• Multi-processor Communication Mode
• Double Speed UART Mode
Data Transmission
A block schematic of the UART transmitter is shown in Figure 45.
Figure 45. UART Transmitter
Data transmission is initiated by writing the data to be transmitted to the UART I/O Data
Register, UDR. Data is transferred from UDR to the Transmit Shift Register when:
70
•
A new character has been written to UDR after the stop bit from the previous
character has been shifted out. The Shift Register is loaded immediately.
•
A new character has been written to UDR before the stop bit from the previous
character has been shifted out. The Shift Register is loaded when the stop bit of the
character currently being transmitted has been shifted out.
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
When data is transferred from UDR to the Shift Register, the UDRE (UART Data Register Empty) bit in the UART Status Register, USR, is set. When this bit is set (one), the
UART is ready to receive the next character. At the same time as the data is transferred
from UDR to the 10(11)-bit Shift Register, bit 0 of the Shift Register is cleared (start bit)
and bit 9 or 10 is set (stop bit). If 9-bit data word is selected (the CHR9 bit in the UART
Control Register, UCR is set), the TXB8 bit in UCR is transferred to bit 9 in the Transmit
Shift Register.
On the Baud Rate clock following the transfer operation to the Shift Register, the start bit
is shifted out on the TXD pin. Then follows the data, LSB first. When the stop bit has
been shifted out, the Shift Register is loaded if any new data has been written to the
UDR during the transmission. During loading, UDRE is set. If there is no new data in the
UDR Register to send when the stop bit is shifted out, the UDRE Flag will remain set
until UDR is written again. When no new data has been written, and the stop bit has
been present on TXD for one bit length, the Transmit Complete Flag, TXC, in USR is
set.
The TXEN bit in UCR enables the UART transmitter when set (one). When this bit is
cleared (zero), the PD1 pin can be used for general I/O. When TXEN is set, the UART
Transmitter will be connected to PD1, which is forced to be an output pin regardless of
the setting of the DDD1 bit in DDRD.
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Data Reception
Figure 46 shows a block diagram of the UART Receiver
Figure 46. UART Receiver
The Receiver front-end logic samples the signal on the RXD pin at a frequency 16 times
the baud rate. While the line is idle, one single sample of logical zero will be interpreted
as the falling edge of a start bit, and the start bit detection sequence is initiated. Let sample 1 denote the first zero-sample. Following the 1 to 0-transition, the receiver samples
the RXD pin at samples 8, 9, and 10. If two or more of these three samples are found to
be logical ones, the start bit is rejected as a noise spike and the receiver starts looking
for the next 1 to 0-transition.
If however, a valid start bit is detected, sampling of the data bits following the start bit is
performed. These bits are also sampled at samples 8, 9, and 10. The logical value found
in at least two of the three samples is taken as the bit value. All bits are shifted into the
Transmitter Shift Register as they are sampled. Sampling of an incoming character is
shown in Figure 47. Note that the description above is not valid when the UART transmission speed is doubled. See “Double Speed Transmission” on page 78 for a detailed
description.
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ATmega163(L)
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ATmega163(L)
Figure 47. Sampling Received Data(1)
Note:
1. This figure is not valid when the UART speed is doubled. See “Double Speed Transmission” on page 78 for a detailed description.
When the stop bit enters the Receiver, the majority of the three samples must be one to
accept the stop bit. If two or more samples are logical zeros, the Framing Error (FE)
Flag in the UART Status Register (USR) is set. Before reading the UDR Register, the
user should always check the FE bit to detect Framing Errors.
Whether or not a valid stop bit is detected at the end of a character reception cycle, the
data is transferred to UDR and the RXC Flag in USR is set. UDR is in fact two physically
separate registers, one for transmitted data and one for received data. When UDR is
read, the Receive Data Register is accessed, and when UDR is written, the Transmit
Data Register is accessed. If 9-bit data word is selected (the CHR9 bit in the UART Control Register, UCR is set), the RXB8 bit in UCR is loaded with bit nine in the Transmit
Shift Register when data is transferred to UDR.
If, after having received a character, the UDR Register has not been read since the last
receive, the OverRun (OR) Flag in UCR is set. This means that the last data byte shifted
into to the Shift Register could not be transferred to UDR and has been lost. The OR bit
is buffered, and is updated when the valid data byte in UDR is read. Thus, the user
should always check the OR bit when reading the UDR Register in order to detect any
overruns if the baud rate is high or CPU load is high.
When the RXEN bit in the UCR Register is cleared (zero), the receiver is disabled. This
means that the PD0 pin can be used as a general I/O pin. When RXEN is set, the UART
Receiver will be connected to PD0, which is forced to be an input pin regardless of the
setting of the DDD0 bit in DDRD. When PD0 is forced to input by the UART, the
PORTD0 bit can still be used to control the pull-up resistor on the pin.
When the CHR9 bit in the UCR Register is set, transmitted and received characters are
9-bit long plus start and stop bits. The ninth data bit to be transmitted is the TXB8 bit in
UCR Register. This bit must be set to the wanted value before a transmission is initated
by writing to the UDR Register. The 9th data bit received is the RXB8 bit in the UCR
Register.
It is important that the Status Register (USR) always is read before the Data Register
(UDR). The Data Register should be read only once for each received byte. Otherwise,
the Status Register (USR) might get updated with incorrect values.
Multi-processor
Communication Mode
The Multi-Processor Communication mode enables several Slave MCUs to receive data
from a Master MCU. This is done by first decoding an address byte to find out which
MCU has been addressed. If a particular Slave MCU has been addressed, it will receive
the following data bytes as normal, while the other Slave MCUs will ignore the data
bytes until another address byte is received.
For an MCU to act as a Master MCU, it should enter 9-bit transmission mode (CHR9 in
UCSRB set). The ninth bit must be one to indicate that an address byte is being transmitted, and zero to indicate that a data byte is being transmitted.
For the Slave MCUs, the mechanism appears slightly differently for 8-bit and 9-bit
reception mode. In 8-bit reception mode (CHR9 in UCSRB cleared), the stop bit is one
for an address byte and zero for a data byte. In 9-bit reception mode (CHR9 in UCSRB
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1142E–AVR–02/03
set), the 9th bit is one for an address byte and zero for a data byte, whereas the stop bit
is always high.
The following procedure should be used to exchange data in Multi-Processor Communication mode:
1. All Slave MCUs are in Multi-Processor Communication mode (MPCM in UCSRA
is set).
2. The Master MCU sends an address byte, and all slaves receive and read this
byte. In the Slave MCUs, the RXC Flag in UCSRA will be set as normal.
3. Each Slave MCU reads the UDR Register and determines if it has been
selected. If so, it clears the MPCM bit in UCSRA, otherwise it waits for the next
address byte.
4. For each received data byte, the receiving MCU will set the Receive Complete
Flag (RXC in UCSRA). In 8-bit mode, the receiving MCU will also generate a
Framing Error (FE in UCSRA set), since the stop bit is zero. The other slave
MCUs, which still have the MPCM bit set, will ignore the data byte. In this case,
the UDR Register and the RXC or FE Flags will not be affected.
5. After the last byte has been transferred, the process repeats from step 2.
UART Control
UART I/O Data Register – UDR
Bit
7
6
5
4
3
2
1
0
$0C ($2C)
MSB
LSB
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
UDR
The UDR Register is actually two physically separate registers sharing the same I/O
address. When writing to the register, the UART Transmit Data Register is written.
When reading from UDR, the UART Receive Data Register is read.
UART Control and Status
Register A – UCSRA
Bit
7
6
5
4
3
2
1
0
$0B ($2B)
RXC
TXC
UDRE
FE
OR
–
U2X
MPCM
Read/Write
r
R/W
R
R
R
R
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
UCSRA
• Bit 7 – RXC: UART Receive Complete
This bit is set (one) when a received character is transferred from the Receiver Shift
Register to UDR. The bit is set regardless of any detected framing errors. When the
RXCIE bit in UCR is set, the UART Receive Complete interrupt will be executed when
RXC is set(one). RXC is cleared by reading UDR. When interrupt-driven data reception
is used, the UART Receive Complete Interrupt routine must read UDR in order to clear
RXC, otherwise a new interrupt will occur once the interrupt routine terminates.
• Bit 6 – TXC: UART Transmit Complete
This bit is set (one) when the entire character (including the stop bit) in the Transmit
Shift Register has been shifted out and no new data has been written to UDR. This Flag
is especially useful in half-duplex communications interfaces, where a transmitting application must enter receive mode and free the communications bus immediately after
completing the transmission.
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ATmega163(L)
When the TXCIE bit in UCR is set, setting of TXC causes the UART Transmit Complete
interrupt to be executed. TXC is cleared by hardware when executing the corresponding
interrupt handling vector. Alternatively, the TXC bit is cleared (zero) by writing a logical
one to the bit.
• Bit 5 – UDRE: UART Data Register Empty
This bit is set (one) when a character written to UDR is transferred to the Transmit Shift
Register. Setting of this bit indicates that the transmitter is ready to receive a new character for transmission.
When the UDRIE bit in UCR is set, the UART Transmit Complete interrupt to be executed as long as UDRE is set. UDRE is cleared by writing UDR. When interrupt-driven
data transmittal is used, the UART Data Register Empty Interrupt routine must write
UDR in order to clear UDRE, otherwise a new interrupt will occur once the interrupt routine terminates.
UDRE is set (one) during reset to indicate that the transmitter is ready.
• Bit 4 – FE: Framing Error
This bit is set if a Framing Error condition is detected, i.e. when the stop bit of an incoming character is zero.
The FE bit is cleared when the stop bit of received data is one.
• Bit 3 – OR: OverRun
This bit is set if an Overrun condition is detected, i.e., when a character already present
in the UDR Register is not read before the next character has been shifted into the
Receiver Shift Register. The OR bit is buffered, which means that it will be set once the
valid data still in UDR is read.
The OR bit is cleared (zero) when data is received and transferred to UDR.
• Bit 2 – Res: Reserved Bit
This bit is a reserved bit in the ATmega163 and will always read as zero.
• Bits 1 – U2X: Double the UART Transmission Speed
Setting this bit will reduce the division of the baud rate generator clock from 16 to 8,
effectively doubling the transfer speed at the expense of robustness. For a detailed
description, see “Double Speed Transmission” on page 78.
• Bit 0 – MPCM: Multi-processor Communication Mode
This bit is used to enter Multi-Processor Communication mode. The bit is set when the
slave MCU waits for an address byte to be received. When the MCU has been
addressed, the MCU switches off the MPCM bit, and starts data reception.
For a detailed description, see “Multi-processor Communication Mode” on page 73.
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UART Control and Status
Register B – UCSRB
Bit
7
6
5
4
3
2
1
0
$0A ($2A)
RXCIE
TXCIE
UDRIE
RXEN
TXEN
CHR9
RXB8
TXB8
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R
W
Initial Value
0
0
0
0
0
0
1
0
UCSRB
• Bit 7 – RXCIE: RX Complete Interrupt Enable
When this bit is set (one), a setting of the RXC bit in USR will cause the Receive Complete interrupt routine to be executed provided that global interrupts are enabled.
• Bit 6 – TXCIE: TX Complete Interrupt Enable
When this bit is set (one), a setting of the TXC bit in USR will cause the Transmit Complete interrupt routine to be executed provided that global interrupts are enabled.
• Bit 5 – UDRIE: UART Data Register Empty Interrupt Enable
When this bit is set (one), a setting of the UDRE bit in USR will cause the UART Data
Register Empty interrupt routine to be executed provided that global interrupts are
enabled.
• Bit 4 – RXEN: Receiver Enable
This bit enables the UART Receiver when set (one). When the Receiver is disabled, the
RXC, OR, and FE Status Flags cannot become set. If these flags are set, turning off
RXEN does not cause them to be cleared.
• Bit 3 – TXEN: Transmitter Enable
This bit enables the UART Transmitter when set (one). When disabling the Transmitter
while transmitting a character, the Transmitter is not disabled before the character in the
Shift Register plus any following character in UDR has been completely transmitted.
• Bit 2 – CHR9: 9-bit Characters
When this bit is set (one) transmitted and received characters are 9-bit long plus start
and stop bits. The ninth bit is read and written by using the RXB8 and TXB8 bits in UCR,
respectively. The ninth data bit can be used as an extra stop bit or a parity bit.
• Bit 1 – RXB8: Receive Data Bit 8
When CHR9 is set (one), RXB8 is the ninth data bit of the received character.
• Bit 0 – TXB8: Transmit Data Bit 8
When CHR9 is set (one), TXB8 is the ninth data bit in the character to be transmitted.
Baud Rate Generator
The Baud Rate generator is a frequency divider which generates baud-rates according
to the following equation:
f CK
BAUD = --------------------------------16(UBR + 1 )
•
76
BAUD = Baud Rate
•
fCK= Crystal Clock frequency
•
UBR = Contents of the UBRRHI and UBRR Registers, (0 - 4095)
ATmega163(L)
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ATmega163(L)
•
Note that this equation is not valid when the UART transmission speed is doubled.
See “Double Speed Transmission” on page 78 for a detailed description.
For standard crystal frequencies, the most commonly used baud rates can be generated
by using the UBR settings in Table 27. UBR values which yield an actual baud rate differing less than 2% from the target baud rate, are bold in the table. However, using baud
rates that have more than 1% error is not recommended. High error ratings give less
noise resistance.
Table 27. UBR Settings at Various Crystal Frequencies
Baud R ate
1 MHz % Error
1,84 MHz % Erro r
2 MHz
% Error
2,458 MHz % Error
2400
UBR=
25
0,2 U BR =
47
0 ,0 U BR =
51
0,2 U BR =
63
0,0
4800
UBR=
12
0,2 U BR =
23
0 ,0 U BR =
25
0,2 U BR =
31
0,0
9600
UBR=
6
7,5 U BR =
11
0 ,0 U BR =
12
0,2 U BR =
15
0,0
14400
UBR=
3
7,8 U BR =
7
0 ,0 U BR =
8
3,7 U BR =
10
3,1
19200
UBR=
2
7,8 U BR =
5
0 ,0 U BR =
6
7,5 U BR =
7
0,0
6,3
28800
UBR=
1
7,8 U BR =
3
0 ,0 U BR =
3
7,8 U BR =
4
38400
UBR=
1
22,9 U BR =
2
0 ,0 U BR =
2
7,8 U BR =
3
0,0
57600
UBR=
0
7,8 U BR =
1
0 ,0 U BR =
1
7,8 U BR =
2
1 2,5
76800
UBR=
0
22,9 U BR =
1
33 ,3 U BR =
1
2 2,9 U BR =
1
0,0
11520 0
UBR=
0
84,3 U BR =
0
0 ,0 U BR =
0
7,8 U BR =
0
2 5,0
Baud R ate
2400
3,28 MHz % Error
UBR=
84
3,69 MHz % Erro r
0,4 U BR =
95
4 MHz
0 ,0 U BR =
103
% Error
4,608 MHz % Error
0,2 U BR =
119
0,0
4800
UBR=
42
0,8 U BR =
47
0 ,0 U BR =
51
0,2 U BR =
59
0,0
9600
UBR=
20
1,6 U BR =
23
0 ,0 U BR =
25
0,2 U BR =
29
0,0
14400
UBR=
13
1,6 U BR =
15
0 ,0 U BR =
16
2,1 U BR =
19
0,0
19200
UBR=
10
3,1 U BR =
11
0 ,0 U BR =
12
0,2 U BR =
14
0,0
28800
UBR=
6
1,6 U BR =
7
0 ,0 U BR =
8
3,7 U BR =
9
0,0
38400
UBR=
4
6,3 U BR =
5
0 ,0 U BR =
6
7,5 U BR =
7
6,7
57600
UBR=
3
12,5 U BR =
3
0 ,0 U BR =
3
7,8 U BR =
4
0,0
76800
UBR=
2
12,5 U BR =
2
0 ,0 U BR =
2
7,8 U BR =
3
6,7
11520 0
UBR=
1
12,5 U BR =
1
0 ,0 U BR =
1
7,8 U BR =
2
2 0,0
Baud R ate
7,37 MHz % Error
8 MHz % Erro r
2400
UBR=
191
0,0 U BR =
2 07
0 ,2
4800
UBR=
95
0,0 U BR =
1 03
0 ,2
9600
UBR=
47
0,0 U BR =
51
0 ,2
14400
UBR=
31
0,0 U BR =
34
0 ,8
19200
UBR=
23
0,0 U BR =
25
0 ,2
28800
UBR=
15
0,0 U BR =
16
2 ,1
38400
UBR=
11
0,0 U BR =
12
0 ,2
57600
UBR=
7
0,0 U BR =
8
3 ,7
76800
UBR=
5
0,0 U BR =
6
7 ,5
11520 0
UBR=
3
0,0 U BR =
3
7 ,8
77
1142E–AVR–02/03
UART Baud Rate Registers –
UBRR and UBRRHI
Bit
15
14
13
12
11
$20 ($40)
–
–
–
–
MSB
$09 ($29)
MSB
7
Read/Write
6
5
4
10
3
9
2
8
1
LSB
UBRRHI
LSB
UBRR
0
R
R
R
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
This is a 12-bit register which contains the UART Baud Rate according to the equation
on the previous page. The UBRRHI contains the four most significant bits, and the
UBRR contains the eight least significant bits of the UART Baud Rate.
Double Speed
Transmission
The ATmega163 provides a separate UART mode which allows the user to double the
communication speed. By setting the U2X bit in the UART Control and Status Register
UCSRA, the UART speed will be doubled. Note, however, that the receiver will in this
case only use half the number of samples (only 8 instead of 16) for data sampling and
clock recovery, and therefore requires more accurate baud rate setting and system
clock.
The data reception will differ slightly from Normal mode. Since the speed is doubled, the
Receiver front-end logic samples the signals on RXD pin at a frequency eight times the
baud rate. While the line is idle, one single sample of logical zero will be interpreted as
the falling edge of a start bit, and the start bit detection sequence is initiated. Let sample
1 denote the first zero-sample. Following the 1 to 0-transition, the Receiver samples the
RXD pin at samples 4, 5, and 6. If two or more of these three samples are found to be
logical ones, the start bit is rejected as a noise spike and the receiver starts looking for
the next 1 to 0-transition.
If however, a valid start bit is detected, sampling of the data bits following the start bit is
performed. These bits are also sampled at samples 4, 5, and 6. The logical value found
in at least two of the three samples is taken as the bit value. All bits are shifted into the
Transmitter Shift Register as they are sampled. Sampling of an incoming character is
shown in Figure 48.
Figure 48. Sampling Received Data When the Transmission Speed is Doubled
RXD
START BIT
D0
D1
D2
D3
D4
D5
D6
D7
STOP BIT
RECEIVER
SAMPLING
The Baud Rate Generator in
Double UART Speed Mode
Note that the baud-rate equation is different from the equation on page 78 when the
UART speed is doubled:
f CK
BAUD = -----------------------------8(UBR + 1 )
•
BAUD = Baud Rate
•
fCK= Crystal Clock frequency
•
UBR = Contents of the UBRRHI and UBRR Registers, (0 - 4095)
•
Note that this equation is only valid when the UART Transmission Speed is doubled.
For standard crystal frequencies, the most commonly used baud rates can be generated
by using the UBR settings in Table 28. UBR values which yield an actual baud rate differing less than 1.5% from the target baud rate, are bold in the table. However, since the
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ATmega163(L)
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ATmega163(L)
number of samples are reduced, and the system clock might have some variance (this
applies especially when using resonators), it is recommended that the baud rate error is
less than 0.5%.
Table 28. UBR Settings at Various Crystal Frequencies in Double Speed Mode
1.0000 MHz
% Error
1.8432 MHz
% Error
2.0000 MHz
% Error
UBR = 51
0.2 UBR = 95
0.0 UBR = 103
0.2
UBR = 25
0.2 UBR = 47
0.0 UBR = 51
0.2
UBR = 12
0.2 UBR = 23
0.0 UBR = 25
0.2
UBR = 8
3.7 UBR = 15
0.0 UBR = 16
2.1
UBR = 6
7.5 UBR = 11
0.0 UBR = 12
0.2
UBR = 3
7.8 UBR = 7
0.0 UBR = 8
3.7
UBR = 2
7.8 UBR = 5
0.0 UBR = 6
7.5
UBR = 1
7.8 UBR = 3
0.0 UBR = 3
7.8
UBR = 1
22.9 UBR = 2
0.0 UBR = 2
7.8
UBR = 0
84.3 UBR = 1
0.0 UBR = 1
7.8
- UBR = 0
3.2768 MHz
% Error
3.6864 MHz
0.0 % Error
4.0000 MHz
% Error
UBR = 170
0.2 UBR = 191
0.0 UBR = 207
0.2
UBR = 84
0.4 UBR = 95
0.0 UBR = 103
0.2
UBR = 42
0.8 UBR = 47
0.0 UBR = 51
0.2
UBR = 27
1.6 UBR = 31
0.0 UBR = 34
0.8
UBR = 20
1.6 UBR = 23
0.0 UBR = 25
0.2
UBR = 13
1.6 UBR = 15
0.0 UBR = 16
2.1
UBR = 10
3.1 UBR = 11
0.0 UBR = 12
0.2
UBR = 6
1.6 UBR = 7
0.0 UBR = 8
3.7
UBR = 4
6.2 UBR = 5
0.0 UBR = 6
7.5
UBR = 3
12.5 UBR = 3
0.0 UBR = 3
7.8
UBR = 1
12.5 UBR = 1
0.0 UBR = 1
7.8
UBR = 0
12.5 UBR = 0
0.0 UBR = 0
7.8
7.3728 MHz
% Error
8.0000 MHz
% Error
UBR = 383
0.0 UBR = 416
0.1
UBR = 191
0.0 UBR = 207
0.2
UBR = 95
0.0 UBR = 103
0.2
UBR = 63
0.0 UBR = 68
0.6
UBR = 47
0.0 UBR = 51
0.2
UBR = 31
0.0 UBR = 34
0.8
UBR = 23
0.0 UBR = 25
0.2
UBR = 15
0.0 UBR = 16
2.1
UBR = 11
0.0 UBR = 12
0.2
UBR = 7
0.0 UBR = 8
3.7
UBR = 3
0.0 UBR = 3
7.8
UBR = 1
0.0 UBR = 1
7.8
UBR = 0
0.0 UBR = 0
7.8
79
1142E–AVR–02/03
Two-wire Serial
Interface (Byte
Oriented)
The Two-wire Serial Interface supports bi-directional serial communication. It is
designed primarily for simple but efficient integrated circuit (IC) control. The system is
comprised of two lines, SCL (Serial Clock) and SDA (Serial Data) that carry information
between the ICs connected to them. Various communication configurations can be
designed using this bus. Figure 49 shows a typical Two-wire Serial Bus configuration.
Any device connected to the bus can be master or slave. Note that all AVR devices connected to the bus must be powered to allow any bus operation.
Figure 49. Two-wire Serial Bus Configuration
V
Device 1
Device 2
Device 3 ....... Device n
R1
CC
R2
SCL
SDA
The Two-wire Serial Interface supports Master/Slave and Transmitter/Receiver operation at up to 217 kHz bus clock rate. The Two-wire Serial Interface has hardware
support for 7-bit addressing, but is easily extended to, e.g., a 10-bit addressing format in
software. When the Two-wire Serial Interface is enabled (TWEN in TWCR is set), a
glitch filter is enabled for the input signals from the pins PC0 (SCL) and PC1 (SDA), and
the output from these pins is slew-rate controlled. The Two-wire Serial Interface is byte
oriented. The operation of the Two-wire Serial Bus is shown as a pulse diagram in Figure 50, including the START and STOP conditions and generation of ACK signal by the
bus receiver.
Figure 50. Two-wire Serial Bus Timing Diagram
ACKNOWLEDGE
FROM RECEIVER
SDA
MSB
SCL
1
START
CONDITION
STOP CONDITION
REPEATED START
CONDITION
R/W
BIT
2
7
8
9
ACK
1
2
8
9
ACK
The block diagram of the Two-wire Serial Interface is shown in Figure 51.
80
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Figure 51. Block Diagram of the Two-wire Serial Interface
ADDRESS REGISTER
AND
COMPARATOR
TWAR
INPUT
SDA
OUTPUT
DATA SHIFT
REGISTER
ACK
INPUT
SCL
OUTPUT
START/STOP
AND SYNC
ARBITRATION
TIMING
AND
CONTROL
SERIAL CLOCK
GENERATOR
CONTROL
REGISTER
AVR 8-BIT DATA BUS
TWDR
TWCR
STATUS
STATE MACHINE
AND
STATUS DECODER
STATUS
REGISTER
TWSR
The CPU interfaces with the Two-wire Serial Interface via the following five I/O Registers: the Two-wire Serial Interface Bit Rate Register (TWBR), the Two-wire Serial
Interface Control Register (TWCR), the Two-wire Serial Interface Status Register
(TWSR), the Two-wire Serial Interface Data Register (TWDR), and the Two-wire Serial
Interface Address Register (TWAR, used in Slave mode).
81
1142E–AVR–02/03
The Two-wire Serial Interface
Bit Rate Register – TWBR
Bit
7
6
5
4
3
2
1
0
TWBR7
TWBR6
TWBR5
TWBR4
TWBR3
TWBR2
TWBR1
TWBR0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
$00 ($20)
TWBR
• Bits 7..0 – Two-wire Serial Interface Bit Rate Register
TWBR selects the division factor for the bit rate generator. The bit rate generator is a
frequency divider which generates the SCL clock frequency in the Master modes
according to the following equation:
f CK
Bit Rate = ----------------------------------------------------------16 + 2(TWBR) + t A f CK
•
Bit Rate = SCL frequency
•
fCK = CPU Clock frequency
•
TWBR = Contents of the Two-wire Serial Interface Bit Rate Register
•
tA = Bus alignment adjustion
Note:
Both the Receiver and the Transmitter can stretch the low period of the SCL line when
waiting for user response, thereby reducing the average bit rate.
TWBR should be set to a value higher than seven to ensure correct Two-wire Serial Bus
functionality. The bus alignment adjustion is automatically inserted by the Two-wire
Serial Interface, and ensures the validity of setup and hold times on the bus for any
TWBR value higher than seven. This adjustment may vary from 200 ns to 600 ns
depending on bus loads and drive capabilities of the devices connected to the bus.
The Two-wire Serial Interface
Control Register – TWCR
Bit
7
6
5
4
3
2
1
0
TWINT
TWEA
TWSTA
TWSTO
TWWC
TWEN
–
TWIE
Read/Write
R/W
R/W
R/W
R/W
R
R/W
R
R/W
Initial Value
0
0
0
0
0
0
0
0
$36 ($56)
TWCR
• Bit 7 – TWINT: Two-wire Serial Interface Interrupt Flag
This bit is set by hardware when the Two-wire Serial Interface has finished its current
job and expects application software response. If the I-bit in the SREG and TWIE in the
TWCR Register are set (one), the MCU will jump to the Interrupt Vector at address $22.
While the TWINT Flag is set, the bus SCL clock line low period is stretched. The TWINT
Flag must be cleared by software by writing a logic one to it. Note that this flag is not
automaticaly cleared by hardware when executing the interrupt routine. Also note that
clearing this flag starts the operation of the Two-wire Serial Interface, so all accesses to
the Two-wire Serial Interface Address Register – TWAR, Two-wire Serial Interface Status Register – TWSR, and Two-wire Serial Interface Data Register – TWDR must be
complete before clearing this flag.
82
ATmega163(L)
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ATmega163(L)
• Bit 6 – TWEA: Two-wire Serial Interface Enable Acknowledge Flag
TWEA Flag controls the generation of the acknowledge pulse. If the TWEA bit is set,
the ACK pulse is generated on the Two-wire Serial Bus if the following conditions are
met:
1. The device’s own slave address has been received.
2. A general call has been received, while the TWGCE bit in the TWAR is set.
3. A data byte has been received in Master Receiver or Slave Receiver mode.
By setting the TWEA bit low, the device can be virtually disconnected from the Two-wire
Serial Bus temporarily. Address recognition can then be resumed by setting the TWEA
bit again.
• Bit 5 – TWSTA: Two-wire Serial Bus START Condition Flag
The TWSTA Flag is set by the application when it desires to become a Master on the
Two-wire Serial Bus. The Two-wire Serial Interface hardware checks if the bus is available, and generates a START condition on the bus if it is free. However, if the bus is not
free, the Two-wire Serial Interface waits until a STOP condition is detected, and then
generates a new START condition to claim the bus Master status.
• Bit 4 – TWSTO: Two-wire Serial Bus STOP Condition Flag
TWSTO is a Stop Condition Flag. In Master mode setting the TWSTO bit in the Control
Register will generate a STOP condition on the Two-wire Serial Bus. When the STOP
condition is executed on the bus, the TWSTO bit is cleared automatically. In Slave mode
setting the TWSTO bit can be used to recover from an error condition. No stop condition
is generated on the bus then, but the Two-wire Serial Interface returns to a well-defined
unaddressed Slave mode and releases the SCL and SDA lines to a high impedance
state.
• Bit 3 – TWWC: Two-wire Serial Bus Write Collision Flag
The TWWC bit is set when attempting to write to the Two-wire Serial Interface Data
Register – TWDR when TWINT is low. This flag is cleared by writing the TWDR Register
when TWINT is high.
• Bit 2 – TWEN: Two-wire Serial Interface Enable Bit
The TWEN bit enables Two-wire Serial Interface operation. If this bit is cleared (zero),
the bus outputs SDA and SCL are set to high impedance state, and the input signals are
ignored. The interface is activated by setting this bit (one).
• Bit 1 – Res: Reserved Bit
This bit is a reserved bit in the ATmega163 and will always read as zero.
83
1142E–AVR–02/03
• Bit 0 – TWIE: Two-wire Serial Interface Interrupt Enable
When this bit is enabled, and the I-bit in SREG is set, the Two-wire Serial Interface interrupt will be activated for as long as the TWINT Flag is high.
The TWCR is used to control the operation of the Two-wire Serial Interface. It is used to
enable the Two-wire Serial Interface, to initiate a Master access by applying a START
condition to the bus, to generate a receiver acknowledge, to generate a stop condition,
and to control halting of the bus while the data to be written to the bus are written to the
TWDR. It also indicates a write collision if data is attempted written to TWDR while the
register is inaccessible.
The Two-wire Serial Interface
Status Register – TWSR
Bit
7
6
5
4
3
2
1
TWS7
TWS6
TWS5
TWS4
TWS3
–
–
–
Read/Write
R
R
R
R
R
R
R
R
Initial Value
1
1
1
1
1
0
0
0
$01 ($21)
0
TWSR
• Bits 7..3 – TWS: Two-wire Serial Interface Status
These five bits reflect the status of the Two-wire Serial Interface logic and the Two-wire
Serial Bus.
• Bits 2..0 – Res: Reserved bits
These bits are reserved in ATmega163 and will always read as zero
The TWSR is read only. It contains a status code which reflects the status of the Twowire Serial Interface logic and the Two-wire Serial Bus. There are 26 possible status
codes. When TWSR contains $F8, no relevant state information is available and no
Two-wire Serial Interface interrupt is requested. A valid status code is available in
TWSR one CPU clock cycle after the Two-wire Serial Interface Interrupt Flag (TWINT) is
set by hardware and is valid until one CPU clock cycle after TWINT is cleared by software. Table 32 to Table 36 give the status information for the various modes.
The Two-wire Serial Interface
Data Register – TWDR
Bit
7
6
5
4
3
2
1
0
TWD7
TWD6
TWD5
TWD4
TWD3
TWD2
TWD1
TWD0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
1
1
1
1
1
1
1
1
$03 ($23)
TWDR
• Bits 7..0 – TWD: Two-wire Serial Interface Data Register
These eight bits constitute the next data byte to be transmitted, or the latest data byte
received on the Two-wire Serial Bus.
In Transmit mode, TWDR contains the next byte to be transmitted. In Receive mode, the
TWDR contains the last byte received. It is writeable while the Two-wire Serial Interface
is not in the process of shifting a byte. This occurs when the Two-wire Serial Interface
Interrupt Flag (TWINT) is set by hardware. Note that the Data Register cannot be initialized by the user before the first interrupt occurs. The data in TWDR remain stable as
long as TWINT is set. While data is shifted out, data on the bus is simultaneously shifted
in. TWDR always contains the last byte present on the bus, except after a wake up from
ADC Noise Reduction mode, Power-down mode, or Power-save mode by the Two-wire
Serial Interface interrupt. For example, in the case of a lost bus arbitration, no data is
lost in the transition from Master to Slave. Handling of the ACK Flag is controlled automatically by the Two-wire Serial Interface logic, the CPU cannot access the ACK bit
directly.
84
ATmega163(L)
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ATmega163(L)
The Two-wire Serial Interface
(Slave) Address Register –
TWAR
Bit
7
6
5
4
3
2
1
0
TWA6
TWA5
TWA4
TWA3
TWA2
TWA1
TWA0
TWGCE
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
1
1
1
1
1
1
1
0
$02 ($22)
TWAR
• Bits 7..1 – TWA: Two-wire Serial Interface (Slave) Address Register
These seven bits constitute the slave address of the Two-wire Serial Bus unit.
• Bit 0 – TWGCE: Two-wire Serial Interface General Call Recognition Enable Bit
This bit enables, if set, the recognition of the General Call given over the Two-wire Serial
Bus.
The TWAR should be loaded with the 7-bit slave address (in the seven most significant
bits of TWAR) to which the Two-wire Serial Interface will respond when programmed as
a Slave Transmitter or Receiver, and not needed in the Master modes. The LSB of
TWAR is used to enable recognition of the general call address ($00). There is an associated address comparator that looks for the slave address (or generall call address if
enabled) in the received serial address. If a match is found, an interrupt request is
generated.
Two-wire Serial Interface
Modes
The Two-wire Serial Interface can operate in four different modes:
•
Master Transmitter
•
Master Receiver
•
Slave Receiver
•
Slave Transmitter
Data transfer in each mode of operation is shown in Figure 52 to Figure 55. These figures contain the following abbreviations:
S: START condition
R: Read bit (high level at SDA)
W: Write bit (low level at SDA)
A: Acknowledge bit (low level at SDA)
A: Not acknowledge bit (high level at SDA)
Data: 8-bit data byte
P: STOP condition
SLA: Slave Address
In Figure 52 to Figure 55, circles are used to indicate that the Two-wire Serial Interface
Interrupt Flag is set. The numbers in the circles show the status code held in TWSR. At
these points, actions must be taken by the application to continue or complete the Twowire Serial Bus transfer. The Two-wire Serial Bus transfer is suspended until the Twowire Serial Interface Interrupt Flag is cleared by software.
The Two-wire Serial Interface Interrupt Flag is not automatically cleared by hardware
when executing the interrupt routine. Software has to clear the flag to continue the Twowire transfer. Also note that the Two-wire Serial Interface starts execution as soon as
this bit is cleared, so that all access to TWAR, TWDR, and TWSR must have been completed before clearing this flag.
85
1142E–AVR–02/03
When the Two-wire Serial Interface Interrupt Flag is set, the status code in TWSR is
used to determine the appropriate software action. For each status code, the required
software action and details of the following serial transfer are given in Table 32 to Table
36.
Master Transmitter Mode In the Master Transmitter mode, a number of data bytes are transmitted to a Slave
Receiver (see Figure 52). Before Master Transmitter mode can be entered, the TWCR
must be initialized as follows:
Table 29. TWCR: Master Transmitter Mode Initialization
TWCR
TWINT
TWEA
TWSTA
TWSTO
TWWC
TWEN
–
TWIE
Value
0
X
0
0
0
1
0
X
TWEN must be set to enable the Two-wire Serial Interface, TWSTA and TWSTO must
be cleared.
The Master Transmitter mode may now be entered by setting the TWSTA bit. The Twowire Serial Interface logic will then test the Two-wire Serial Bus and generate a START
condition as soon as the bus becomes free. When a START condition is transmitted, the
Two-wire Serial Interface Interrupt Flag (TWINT) is set by hardware, and the status code
in TWSR will be $08. TWDR must then be loaded with the slave address and the data
direction bit (SLA+W). Clearing the TWINT bit in software will continue the transfer. The
TWINT Flag is cleared by writing a logic one to the flag.
When the slave address and the direction bit have been transmitted and an acknowledgement bit has been received, TWINT is set again and a number of status codes in
TWSR are possible. Possible status codes in Master mode are $18, $20, or $38. The
appropriate action to be taken for each of these status codes is detailed in Table 32. The
data must be loaded when TWINT is high only. If not, the access will be discarded, and
the Write Collision bit – TWWC will be set in the TWCR Register. This scheme is
repeated until the last byte is sent and the transfer is ended by generating a STOP condition or a repeated START condition. A STOP condition is generated by setting
TWSTO, a repeated START condition is generated by setting TWSTA and TWSTO.
After a repeated START condition (state $10) the Two-wire Serial Interface can access
the same Slave again, or a new Slave without transmitting a STOP condition. Repeated
START enables the Master to switch between Slaves, Master Transmitter mode and
Master Receiver mode without loosing control over the bus.
Assembly code illustrating operation of the Master Transmitter mode is given at the end
of the TWI section.
Master Receiver Mode
In the Master Receiver mode, a number of data bytes are received from a Slave Transmitter (see Figure 53). The transfer is initialized as in the Master Transmitter mode.
When the START condition has been transmitted, the TWINT Flag is set by hardware.
The software must then load TWDR with the 7-bit slave address and the Data Direction
bit (SLA+R). The transfer will then continue when the TWINT Flag is cleared by
software.
When the slave address and the direction bit have been transmitted and an acknowledgement bit has been received, TWINT is set again and a number of status codes in
TWSR are possible. Possible status codes in Master mode are $40, $48, or $38. The
appropriate action to be taken for each of these status codes is detailed in Table 52.
Received data can be read from the TWDR Register when the TWINT Flag is set high
by hardware. This scheme is repeated until the last byte has been received and a STOP
condition is transmitted by writing a logic one to the TWSTO bit in the TWCR Register.
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ATmega163(L)
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ATmega163(L)
After a repeated START condition (state $10), the Two-wire Serial Interface may switch
to the Master Transmitter mode by loading TWDR with SLA+W or access a new Slave
as Master Receiver or Transmitter.
Assembly code illustrating operation of the Master Receiver mode is given at the end of
the TWI section.
Slave Receiver Mode
In the Slave Receiver mode, a number of data bytes are received from a Master Transmitter (see Figure 54). To initiate the Slave Receiver mode, TWAR and TWCR must be
initialized as follows:
Table 30. TWAR: Slave Receiver Mode Initialization
TWAR
TWA6
TWA5
Value
TWA4
TWA3
TWA2
TWA1
TWA0
TWGCE
Device’s Own Slave Address
The upper seven bits are the address to which the Two-wire Serial Interface will respond
when addressed by a Master. If the LSB is set, the Two-wire Serial Interface will
respond to the general call address ($00), otherwise it will ignore the general call
address.
Table 31. WCR: Slave Receiver Mode Initialization
TWCR
TWINT
TWEA
TWSTA
TWSTO
TWWC
TWEN
–
TWIE
Value
0
1
0
0
0
1
0
X
TWEN must be set to enable the Two-wire Serial Interface. The TWEA bit must be set to
enable the acknowledgement of the device’s own slave address or the general call
address. TWSTA and TWSTO must be cleared.
When TWAR and TWCR have been initialized, the Two-wire Serial Interface waits until
it is addressed by its own slave address (or the general call address if enabled) followed
by the Data Direction bit which must be “0” (write) for the Two-wire Serial Interface to
operate in the Slave Receiver mode. After its own slave address and the write bit have
been received, the Two-wire Serial Interface Interrupt Flag is set and a valid status code
can be read from TWSR. The status code is used to determine the appropriate software
action. The appropriate action to be taken for each status code is detailed in Table 34.
The Slave Receiver mode may also be entered if arbitration is lost while the Two-wire
Serial Interface is in the Master mode (see states $68 and $78).
If the TWEA bit is reset during a transfer, the Two-wire Serial Interface will return a “Not
Acknowledge” (“1”) to SDA after the next received data byte. While TWEA is Reset, the
Two-wire Serial Interface does not respond to its own slave address. However, the Twowire Serial Bus is still monitored and address recognition may resume at any time by
setting TWEA. This implies that the TWEA bit may be used to temporarily isolate the
Two-wire Serial Interface from the Two-wire Serial Bus.
In ADC Noise Reduction mode, Power-down mode, and Power-save mode, the clock
system to the Two-wire Serial Interface is turned off. If the Slave Receive mode is
enabled, the interface can still acknowledge a general call and its own slave address by
using the Two-wire Serial Bus clock as a clock source. The part will then wake-up from
sleep and the Two-wire Serial Interface will hold the SCL clock wil low during the wakeup and until the TWINT Flag is cleared.
Note that the Two-wire Serial Interface Data Register – TWDR – does not reflect the last
byte present on the bus when waking up from these sleep modes.
Assembly code illustrating operation of the Slave Receiver mode is given at the end of
the TWI section.
87
1142E–AVR–02/03
Slave Transmitter Mode
In the Slave Transmitter mode, a number of data bytes are transmitted to a Master
Receiver (see Figure 55). The transfer is initialized as in the Slave Receiver mode.
When TWAR and TWCR have been initialized, the Two-wire Serial Interface waits until
it is addressed by its own slave address (or the general call address if enabled) followed
by the Data Direction bit which must be “1” (read) for the Two-wire Serial Interface to
operate in the Slave Transmitter mode. After its own slave address and the read bit
have been received, the Two-wire Serial Interface Interrupt Flag is set and a valid status
code can be read from TWSR. The status code is used to determine the appropriate
software action. The appropriate action to be taken for each status code is detailed in
Table 35. The slave transmitter mode may also be entered if arbitration is lost while the
Two-wire Serial Interface is in the Master mode (see state $B0).
If the TWEA bit is reset during a transfer, the Two-wire Serial Interface will transmit the
last byte of the transfer and enter state $C0 or state $C8. the Two-wire Serial Interface
is switched to the not addressed Slave mode, and will ignore the Master if it continues
the transfer. Thus the Master Receiver receives all “1” as serial data. While TWEA is
reset, the Two-wire Serial Interface does not respond to its own slave address. However, the Two-wire Serial Bus is still monitored and address recognition may resume at
any time by setting TWEA. This implies that the TWEA bit may be used to temporarily
isolate the Two-wire Serial Interface from the Two-wire Serial Bus.
Assembly code illustrating operation of the Slave Receiver mode is given at the end of
the TWI section.
Miscellaneous States
There are two status codes that do not correspond to a defined Two-wire Serial Interface state, see Table 36.
Status $F8 indicates that no relevant information is available because the Two-wire
Serial Interface Interrupt Flag (TWINT) is not set yet. This occurs between other states,
and when the Two-wire Serial Interface is not involved in a serial transfer.
Status $00 indicates that a bus error has occured during a Two-wire Serial Bus transfer.
A bus error occurs when a START or STOP condition occurs at an illegal position in the
format frame. Examples of such illegal positions are during the serial transfer of an
address byte, a data byte or an acknowledge bit. When a bus error occurs, TWINT is
set. To recover from a bus error, the TWSTO Flag must set and TWINT must be cleared
by writing a logic one to it. This causes the Two-wire Serial Interface to enter the not
addressed Slave mode and to clear the TWSTO Flag (no other bits in TWCR are
affected). The SDA and SCL lines are released and no STOP condition is transmitted.
88
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Table 32. Status Codes for Master Transmitter Mode
Application Software Response
Status Code
(TWSR)
Status of the Two-wire Serial
Bus and Two-wire Serial Interface Hardware
To TWCR
To/from TWDR
STA
STO
TWINT
TWEA
Next Action Taken by Two-wire Serial Interface Hardware
$08
A START condition has been
transmitted
Load SLA+W
X
0
1
X
SLA+W will be transmitted;
ACK or NOT ACK will be received
$10
A repeated START condition
has been transmitted
Load SLA+W or
X
0
1
X
Load SLA+R
X
0
1
X
SLA+W will be transmitted;
ACK or NOT ACK will be received
SLA+R will be transmitted;
Logic will switch to Master Receiver mode
Load data byte or
0
0
1
X
No TWDR action or
No TWDR action or
1
0
0
1
1
1
X
X
No TWDR action
1
1
1
X
Load data byte or
0
0
1
X
No TWDR action or
No TWDR action or
1
0
0
1
1
1
X
X
No TWDR action
1
1
1
X
Load data byte or
0
0
1
X
No TWDR action or
No TWDR action or
1
0
0
1
1
1
X
X
No TWDR action
1
1
1
X
Load data byte or
0
0
1
X
No TWDR action or
No TWDR action or
1
0
0
1
1
1
X
X
No TWDR action
1
1
1
X
No TWDR action or
0
0
1
X
No TWDR action
1
0
1
X
$18
$20
$28
$30
$38
SLA+W has been transmitted;
ACK has been received
SLA+W has been transmitted;
NOT ACK has been received
Data byte has been transmitted;
ACK has been received
Data byte has been transmitted;
NOT ACK has been received
Arbitration lost in SLA+W or
data bytes
Data byte will be transmitted and ACK or NOT ACK will
be received
Repeated START will be transmitted
STOP condition will be transmitted and
TWSTO Flag will be Reset
STOP condition followed by a START condition will be
transmitted and TWSTO Flag will be reset
Data byte will be transmitted and ACK or NOT ACK will
be received
Repeated START will be transmitted
STOP condition will be transmitted and
TWSTO Flag will be Reset
STOP condition followed by a START condition will be
transmitted and TWSTO Flag will be Reset
Data byte will be transmitted and ACK or NOT ACK will
be received
Repeated START will be transmitted
STOP condition will be transmitted and
TWSTO Flag will be Reset
STOP condition followed by a START condition will be
transmitted and TWSTO Flag will be Reset
Data byte will be transmitted and ACK or NOT ACK will
be received
Repeated START will be transmitted
STOP condition will be transmitted and
TWSTO Flag will be Reset
STOP condition followed by a START condition will be
transmitted and TWSTO Flag will be Reset
Two-wire Serial Bus will be released and not addressed
Slave mode entered
A START condition will be transmitted when the bus becomes free
89
1142E–AVR–02/03
Figure 52. Formats and States in the Master Transmitter Mode
MT
Successfull
Transmission
to a Slave
Receiver
S
SLA
W
A
DATA
A
$18
$08
P
$28
Next Transfer
Started with a
Repeated Start
Condition
S
SLA
W
$10
Not Acknowledge
Received After the
Slave Address
A
R
P
$20
MR
Not Acknowledge
Received After a Data
Byte
A
P
$30
Arbitration Lost in Slave
Address or Data Byte
A or A
Other Master
Continues
A or A
$38
Arbitration Lost and
Addressed as Slave
A
$68
From Master to Slave
From Slave to Master
Assembly Code Example –
Master Transmitter Mode
Other Master
Continues
$38
Other Master
Continues
$78
To Corresponding
States in Slave Mode
$B0
DATA
A
n
Any Number of Data Bytes
and their Associated Acknowledge Bits
This Number (Contained in TWSR) Corresponds
to a Defined State of the Two-wire Serial Bus
;The Slave being addressed has address 0x64. The code examples also assumes
some sort of error handling routine named ERROR.
;Part specific include file and TWI include file must be included.
; <Initialize registers, including TWAR, TWBR and TWCR>
ldi
r16, (1<<TWSTA) | (1<<TWEN)
out
TWCR, r16
wait1: in
r16,TWCR
sbrs r16,TWINT
; Send START condition
; Wait for TWINT Flag set. This indicates that
; the START condition has been transmitted
rjmp wait1
90
in
r16, TWSR
; Check value of TWI Status Register.
cpi
r16, START
; If status different from START go to ERROR
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
brne ERROR
ldi
r16, 0xc8
; Load SLA+W into TWDR Register
out
TWDR, r16
ldi
r16, (1<<TWINT) | (1<<TWEN)
out
address
TWCR, r16
; Clear TWINT bit in TWCR to start transmission of
wait2:in
r16, TWCR
; Wait for TWINT Flag set. This indicates that
sbrs
r16, TWINT ; SLA+W has been transmitted, and ACK/NACK has
rjmp
wait2
; been received
in
r16, TWSR
; Check value of TWI Status Register. If status
cpi
r16, MT_SLA_ACK; different from MT_SLA_ACK, go to ERROR
brne
ERROR
ldi
r16, 0x33
out
TWDR, r16
ldi
r16, (1<<TWINT) | (1<<TWEN)
out
TWCR, r16 ; Clear TWINT bit in TWCR to start transmission of data
wait3:in
; Load data (here, data = 0x33) into TWDR Register
r16, TWCR ; Wait for TWINT flag set. This indicates that
sbrs
r16, TWINT; data has been transmitted, and ACK/NACK has
rjmp
wait3
in
r16, TWSR ; Check value of TWI Status Register. If status
cpi
r16, MT_DATA_ACK ; different from MT_DATA_ACK, go to ERROR
brne
ERROR
ldi
r16, 0x44 ; Load data (here, data = 0x44) into TWDR Register
out
TWDR, r16
ldi
r16, (1<<TWINT) | (1<<TWEN)
out
TWCR, r16 ; Clear TWINT bit in TWCR to start transmission of data
; been received
;<send more data bytes if needed>
wait4:in
r16, TWCR ; Wait for TWINT flag set. This indicates that
sbrs
r16, TWINT; data has been transmitted, and ACK/NACK has
rjmp
wait4
in
r16, TWSR ; Check value of TWI Status Register. If status
cpi
r16, MT_DATA_ACK; different from MT_DATA_ACK, go to ERROR
brne
ERROR
ldi
r16, (1<<TWINT) | (1<<TWSTO) | (1<<TWEN)
out
TWCR, r16 ; Transmit STOP condition
; been received
91
1142E–AVR–02/03
Table 33. Status Codes for Master Receiver Mode
Application Software Response
Status Code
(TWSR)
Status of the Two-wire Serial
Bus and Two-wire Serial Interface hardware
To TWCR
To/from TWDR
STA
STO
TWINT
TWEA
Next Action Taken by Two-wire Serial Interface Hardware
$08
A START condition has been
transmitted
Load SLA+R
X
0
1
X
SLA+R will be transmitted
ACK or NOT ACK will be received
$10
A repeated START condition
has been transmitted
Load SLA+R or
X
0
1
X
Load SLA+W
X
0
1
X
SLA+R will be transmitted
ACK or NOT ACK will be received
SLA+W will be transmitted
Logic will switch to Master Transmitter mode.
No TWDR action or
0
0
1
X
No TWDR actio
1
0
1
X
0
$38
Arbitration lost in SLA+R or
NOT ACK bit
$40
SLA+R has been transmitted;
ACK has been received
No TWDR action or
0
0
1
No TWDR action
0
0
1
1
$48
SLA+R has been transmitted;
NOT ACK has been received
No TWDR action or
No TWDR action or
1
0
0
1
1
1
X
X
No TWDR action
1
1
1
X
0
$50
Data byte has been received;
ACK has been returned
Read data byte or
0
0
1
Read data byte
0
0
1
1
$58
Data byte has been received;
NOT ACK has been returned
Read data byte or
Read data byte or
1
0
0
1
1
1
X
X
Read data byte
1
1
1
X
Two-wire Serial Bus will be released and not addressed
Slave mode will be entered
A START condition will be transmitted when the bus
becomes free
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
Repeated START will be transmitted
STOP condition will be transmitted and TWSTO Flag
will be Reset
STOP condition followed by a START condition will be
transmitted and TWSTO Flag will be Reset
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
Repeated START will be transmitted
STOP condition will be transmitted and TWSTO Flag
will be Reset
STOP condition followed by a START condition will be
transmitted and TWSTO Flag will be Reset
Figure 53. Formats and States in the Master Receiver Mode
MR
Successfull
Reception
From a Slave
Receiver
S
SLA
$08
R
A
DATA
$40
A
DATA
$50
A
P
$58
Next Transfer
Started with a
Repeated Start
Condition
S
SLA
R
$10
Not Acknowledge
Received After the
Slave Address
A
W
P
$48
MT
Arbitration Lost in Slave
Address or Data Byte
A or A
Other Master
Continues
$38
Arbitration Lost and
Addressed as Slave
A
$68
From Master to Slave
From Slave to Master
92
A
Other Master
Continues
$38
Other Master
Continues
$78
DATA
To corresponding
states in slave mode
$B0
A
n
Any Number of Data Bytes
and their Associated Acknowledge Bits
This Number (Contained in TWSR) Corresponds
to a Defined State of the Two-wire Serial Bus
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Assembly Code Example –
Master Receiver Mode
;Part specific include file and TWI include file must be included.
; <Initialize registers TWAR and TWBR>
ldi
r16, (1<<TWINT) | (1<<TWSTA) | (1<<TWEN)
out
TWCR, r16
wait5:in
;Send START condition
r16,TWCR
; Wait for TWINT flag set. This indicates that
sbrs
r16, TWINT
; the START condition has been transmitted
rjmp
wait5
in
r16, TWSR
; Check value of TWI Status Register. If status
cpi
r16, START
; different from START, go to ERROR
brne
ERROR
ldi
r16, 0xc9
out
TWDR, r16
ldi
r16, (1<<TWINT) | (1<<TWEN)
out
TWCR, r16
wait6:in
r16,TWCR
; Load SLA+R into TWDR Register
; Clear TWINT bit in TWCR to start transmission of
; SLA+R
; Wait for TWINT flag set. This indicates that
sbrs
r16, TWINT
; SLA+R has been transmitted, and ACK/NACK has
rjmp
wait6
; been received
in
r16, TWSR
cpi
r16, MR_SLA_ACK; different from MR_SLA_ACK, go to ERROR
brne
ERROR
ldi
r16, (1<<TWINT) | (1<<TWEA) | (1<<TWEN)
out
TWCR, r16
;
;
;
;
r16,TWCR
; Wait for TWINT flag set. This indicates that
sbrs
r16, TWINT
; data has been received and ACK returned
rjmp
wait7
in
r16, TWSR
cpi
r16, MR_DATA_ACK ; different from MR_DATA_ACK, go to ERROR
brne
ERROR
in
r16, TWDR
wait7:in
nop
; Check value of TWI Status Register. If status
Clear TWINT bit in TWCR to start reception of
data.
Setting TWEA causes ACK to be returned after
reception of data byte
; Check value of TWI Status Register. If status
; Input received data from TWDR.
;<do something with received data>
ldi
r16, (1<<TWINT) | (1<<TWEA) | (1<<TWEN)
out
TWCR, r16
; Clear TWINT bit in TWCR to start reception of
; data. Setting TWEA causes ACK to be returned
; after reception of data byte
;<Receive more data bytes if needed>
;receive next to last data byte.
wait8:in
r16,TWCR
; Wait for TWINT flag set. This indicates that
93
1142E–AVR–02/03
sbrs
r16, TWINT
rjmp
wait8
in
r16, TWSR
cpi
r16, MR_DATA_ACK ; different from MR_DATA_ACK, go to ERROR
brne
ERROR
in
r16, TWDR
nop
; Check value of TWI Status Register. If status
; Input received data from TWDR.
;<do something with received data>
ldi
r16, (1<<TWINT) | (1<<TWEN)
out
TWCR, r16
wait9:in
;
;
;
;
;
Clear TWINT bit in TWCR to start reception of
data. Not setting TWEA causes NACK to be
returned after reception of next data byte
receive last data byte. Signal this to slave by
returning NACK
r16,TWCR
; Wait for TWINT flag set. This indicates that
sbrs
r16, TWINT
; data has been received and NACK returned
rjmp
wait9
in
r16, TWSR
cpi
r16, MR_DATA_NACK ; different from MR_DATA_NACK, go to ERROR
brne
ERROR
in
r16, TWDR
nop
94
; data has been received and ACK returned
; Check value of TWI Status Register. If status
; Input received data from TWDR.
;<do something with received data>
ldi
r16, (1<<TWINT) | (1<<TWSTO) | (1<<TWEN)
out
TWCR, r16
; Send STOP signal
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Table 34. Status Codes for Slave Receiver Mode
Application Software Response
Status code
(TWSR)
Status of the Two-wire Serial Bus
and Two-wire Serial Interface
hardware
To TWCR
To/from TWDR
STA
STO
TWINT
TWEA
X
0
1
0
$60
Own SLA+W has been received;
ACK has been returned
No TWDR action or
No TWDR action
X
0
1
1
$68
Arbitration lost in SLA+R/W as
master; own SLA+W has been
received; ACK has been returned
No TWDR action or
X
0
1
0
No TWDR action
X
0
1
1
$70
General call address has been
received; ACK has been returned
No TWDR action or
X
0
1
0
No TWDR action
X
0
1
1
$78
Arbitration lost in SLA+R/W as
master; General call address has
been received; ACK has been
returned
No TWDR action or
X
0
1
0
No TWDR action
X
0
1
1
$80
Previously addressed with own
SLA+W; data has been received;
ACK has been returned
Read data byte or
X
0
1
0
Read data byte
X
0
1
1
$88
Previously addressed with own
SLA+W; data has been received;
NOT ACK has been returned
Read data byte or
0
0
1
0
Read data byte or
0
0
1
1
Read data byte or
1
0
1
0
Read data byte
1
0
1
1
0
1
0
$90
Previously addressed with
general call; data has been received; ACK has been returned
Read data byte or
X
Read data byte
X
0
1
1
$98
Previously addressed with
general call; data has been
received; NOT ACK has been
returned
Read data byte or
0
0
1
0
Read data byte or
0
0
1
1
Read data byte or
1
0
1
0
Read data byte
1
0
1
1
Read data byte or
0
0
1
0
Read data byte or
0
0
1
1
Read data byte or
1
0
1
0
Read data byte
1
0
1
1
$A0
A STOP condition or repeated
START condition has been
received while still addressed as
slave
Next Action Taken by Two-wire Serial Interface Hardtware
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
Switched to the not addressed Slave mode;
no recognition of own SLA or GCA
Switched to the not addressed Slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”
Switched to the not addressed Slave mode;
no recognition of own SLA or GCA;
a START condition will be transmitted when the bus
becomes free
Switched to the not addressed Slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”;
a START condition will be transmitted when the bus
becomes free
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
Switched to the not addressed Slave mode;
no recognition of own SLA or GCA
Switched to the not addressed Slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”
Switched to the not addressed Slave mode;
no recognition of own SLA or GCA;
a START condition will be transmitted when the bus
becomes free
Switched to the not addressed Slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”;
a START condition will be transmitted when the bus
becomes free
Switched to the not addressed Slave mode;
no recognition of own SLA or GCA
Switched to the not addressed Slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”
Switched to the not addressed Slave mode;
no recognition of own SLA or GCA;
a START condition will be transmitted when the bus
becomes free
Switched to the not addressed Slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”;
a START condition will be transmitted when the bus
becomes free
95
1142E–AVR–02/03
Figure 54. Formats and States in the Slave Receiver Mode
Reception of the Own
Slave Address and One or
More Data Bytes. All are
Acknowledged
S
SLA
W
A
DATA
$60
A
DATA
$80
Last Data Byte Received
is not Acknowledged
A
P or S
$80
$A0
A
P or S
$88
Arbitration Lost as Master
and Addressed as Slave
A
$68
Reception of the General Call
Address and One or More Data
Bytes
General Call
A
DATA
$70
A
DATA
$90
Last Data Byte Received is
not Acknowledged
A
P or S
$90
$A0
A
P or S
$98
Arbitration Lost as Master and
Addressed as Slave by General Call
A
$78
From Master to Slave
From Slave to Master
Assembly Code Example –
Slave Receiver Mode
DATA
A
n
Any Number of Data Bytes
and their Associated Acknowledge Bits
This Number (Contained in TWSR) Corresponds
to a Defined State of the Two-wire Serial Bus
;Part specific include file and TWI include file must be included.
; <Initialize registers TWAR and TWBR>
ldi
r16, (1<<TWINT) | (1<<TWEA) | (1<<TWEN)
out
TWCR, r16
; Enable TWI in Slave Receiver Mode
; <Receive START condition and SLA+W>
wait10:in
96
r16,TWCR
; Wait for TWINT flag set. This indicates that
sbrs
r16, TWINT
; START followed by SLA+W has been received
rjmp
wait10
in
r16, TWSR
cpi
r16, SR_SLA_ACK ; different from SR_SLA_ACK, go to ERROR
; Check value of TWI Status Register. If status
brne
ERROR
ldi
r16, (1<<TWINT) | (1<<TWEA) | (1<<TWEN)
out
TWCR, r16
; Clear TWINT bit in TWCR to start reception of
; first data byte. Setting TWEA indicates that
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
; ACK should be returned after receiving first
; data byte
wait12:in
r16,TWCR
; Wait for TWINT flag set. This indicates that
sbrs
r16, TWINT
rjmp
wait12
in
r16, TWSR
cpi
r16, SR_DATA_ACK ; different from SR_DATA_ACK, go to ERROR
brne
ERROR
in
r16, TWDR
nop
; data has been received and ACK returned
; Check value of TWI Status Register. If status
; Input received data from TWDR.
;<do something with received data>
ldi
r16, (1<<TWINT) | (1<<TWEN)
out
TWCR, r16
wait13:in
; Clear TWINT bit in TWCR to start reception of
; data. Not setting TWEA causes NACK to be
; returned after reception of next data byte
r16,TWCR
; Wait for TWINT flag set. This indicates that
sbrs
r16, TWINT
; data has been received and NACK returned
rjmp
wait13
in
r16, TWSR
cpi
r16, SR_DATA_NACK ; different from SR_DATA_NACK, go to ERROR
brne
ERROR
in
r16, TWDR
nop
; Check value of TWI Status Register. If status
; Input received data from TWDR.
;<do something with received data>
ldi
r16, (1<<TWINT) | (1<<TWEA) | (1<<TWEN)
out
TWCR, r16
;
;
;
;
Clear TWINT bit in TWCR to start reception of
data. Setting TWEA causes TWI unit to enter
not addressed slave mode with reckognition of
own SLA
;<Wait for next data transmission or do something else>
97
1142E–AVR–02/03
Table 35. Status Codes for Slave Transmitter Mode
Application Software Response
Status Code
(TWSR)
$A8
$B0
$B8
$C0
$C8
Status of the Two-wire Serial Bus
and Two-wire Serial Interface
hardware
To TWCR
To/from TWDR
STA
STO
TWINT
TWEA
Load data byte or
X
0
1
0
Load data byte
X
0
1
1
Arbitration lost in SLA+R/W as
master; own SLA+R has been
received; ACK has been returned
Load data byte or
X
0
1
0
Load data byte
X
0
1
1
Data byte in TWDR has been
transmitted; ACK has been
received
Load data byte or
X
0
1
0
Load data byte
X
0
1
1
Data byte in TWDR has been
transmitted; NOT ACK has been
received
No TWDR action or
0
0
1
0
No TWDR action or
0
0
1
1
No TWDR action or
1
0
1
0
No TWDR action
1
0
1
1
No TWDR action or
0
0
1
0
No TWDR action or
0
0
1
1
No TWDR action or
1
0
1
0
No TWDR action
1
0
1
1
Own SLA+R has been received;
ACK has been returned
Last data byte in TWDR has been
transmitted (TWEA = “0”); ACK
has been received
Next Action Taken by Two-wire Serial Interface Hardware
Last data byte will be transmitted and NOT ACK should
be received
Data byte will be transmitted and ACK should be received
Last data byte will be transmitted and NOT ACK should
be received
Data byte will be transmitted and ACK should be received
Last data byte will be transmitted and NOT ACK should
be received
Data byte will be transmitted and ACK should be received
Switched to the not addressed Slave mode;
no recognition of own SLA or GCA
Switched to the not addressed Slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”
Switched to the not addressed Slave mode;
no recognition of own SLA or GCA;
a START condition will be transmitted when the bus
becomes free
Switched to the not addressed Slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”;
a START condition will be transmitted when the bus
becomes free
Switched to the not addressed Slave mode;
no recognition of own SLA or GCA
Switched to the not addressed Slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”
Switched to the not addressed slave mode;
no recognition of own SLA or GCA;
a START condition will be transmitted when the bus
becomes free
Switched to the not addressed Slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”;
a START condition will be transmitted when the bus
becomes free
Figure 55. Formats and States in the Slave Transmitter Mode
Reception of the Own
Slave Address and One or
More Data Bytes
S
SLA
R
A
DATA
$A8
Arbitration Lost as Master
and Addressed as Slave
A
DATA
$B8
A
P or S
$C0
A
$B0
Last Data Byte Transmitted.
Switched to not Addressed
Slave (TWEA = "0")
A
All 1's
P or S
$C8
From Master to Slave
From Slave to Master
98
DATA
A
n
Any Number of Data Bytes
and their Associated Acknowledge Bits
This Number (Contained in TWSR) Corresponds
to a Defined State of the Two-wire Serial Bus
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Assembly Code Example –
Slave Transmitter Mode
; Part specific include file and TWI include file must be included.
; <Initialize registers, including TWAR, TWBR and TWCR>
ldi
r16, (1<<TWINT) | (1<<TWEA) | (1<<TWEN)
out
TWCR, r16
Transmitter Mode
; Enable TWI in Slave
; <Receive START condition and SLA+R>
wait14:in
r16,TWCR
; Wait for TWINT flag set. This indicates that
sbrs r16, TWINT
; SLA+R has been received, and ACK/NACK has
rjmp wait14
; been returned
in
r16, TWSR
; Check value of TWI Status Register. If status
cpi
r16, ST_SLA_ACK; different from ST_SLA_ACK, go to ERROR
brne ERROR
ldi
r16, 0x33
out
TWDR, r16
; Load data (here, data = 0x33) into TWDR Register
ldi
r16, (1<<TWINT) | (1<<TWEA) | (1<<TWEN)
out
TWCR, r16
; Clear TWINT bit in TWCR to start transmission of
; data. Setting TWEA indicates that ACK should be
; received when transfer finished
; <Send more data bytes if needed>
wait15: in
r16,TWCR ; Wait for TWINT flag set. This indicates that
sbrs
r16, TWINT ; data has been transmitted, and ACK/NACK has
rjmp
wait15
; been received
in
r16, TWSR
; Check value of TWI Status Register. If status
cpi
r16, ST_DATA_ACK ; different from ST_DATA_ACK, go to ERROR
brne
ERROR
ldi
r16, 0x44
out
TWDR, r16
ldi
r16, (1<<TWINT) | (1<<TWEA) | (1<<TWEN)
out
TWCR, r16
; Clear TWINT bit in TWCR to start transmission of
; data. Setting TWEA indicates that ACK should be
; received when transfer finished
r16,TWCR
; Wait for TWINT flag set. This indicates that
wait16:in
; Load data (here, data = 0x44) into TWDR Register
sbrs
r16, TWINT ; data has been transmitted, and ACK/NACK has
rjmp
wait16
; been received
in
r16, TWSR
; Check value of TWI Status Register. If status
cpi
r16, ST_DATA_ACK ; different from ST_DATA_ACK, go to ERROR
brne
ERROR
ldi
r16, 0x55
out
TWDR, r16
ldi
r16, (1<<TWINT) | (1<<TWEN)
out
TWCR, r16
; Load data (here, data = 0x55) into TWDR Register
; Clear TWINT bit in TWCR to start transmission of
; data. Not setting TWEA indicates that NACK should
99
1142E–AVR–02/03
; be received after data byte Master signalling end
; of transmission)
wait17:in
r16,TWCR
; Wait for TWINT flag set. This indicates that
sbrs
r16, TWINT ; data has been transmitted, and ACK/NACK has
rjmp
wait17
; been received
in
r16, TWSR
; Check value of TWI Status Register. If status
cpi
r16, ST_LAST_DATA ; different from ST_LAST_DATA, go to ERROR
brne
ERROR
ldi
r16, (1<<TWINT) | (1<<TWEA) | (1<<TWEN)
out
TWCR, r16
Transmitter mode
; Continue address reckognition in Slave
Table 36. Status Codes for Miscellaneous States
Application Software Response
Status Code
(TWSR)
Status of the Two-wire Serial
Bus and Two-wire Serial Interface hardware
To/from TWDR
$F8
No relevant state information
available; TWINT = “0”
No TWDR action
$00
Bus error due to an illegal
START or STOP condition
No TWDR action
TWI Include File
To TWCR
STA
STO
TWINT
TWEA
No TWCR action
0
1
1
Next Action Taken by Two-wire Serial Interface Hardware
Wait or proceed current transfer
X
Only the internal hardware is affected, no STOP condition is sent on the bus. In all cases, the bus is released
and TWSTO is cleared.
;***** General Master staus codes *****
.equ
START
transmitted
=$08
.equ
REP_START
transmitted
=$10
;START has been
;Repeated START has been
;***** Master Transmitter staus codes *****
.equ
MT_SLA_ACK
=$18
;SLA+W has been tramsmitted and ACK received
.equ
MT_SLA_NACK
=$20
;SLA+W has been tramsmitted and NACK received
.equ
MT_DATA_ACK
=$28
;Data byte has been tramsmitted and ACK
;received
.equ
MT_DATA_NACK
received
=$30
;Data byte has been tramsmitted and NACK
.equ
=$38
;Arbitration lost in SLA+W or data bytes
MT_ARB_LOST
;***** Master Receiver staus codes *****
.equ
MR_ARB_LOST
=$38
;Arbitration lost in SLA+R or NACK bit
.equ
MR_SLA_ACK
=$40
;SLA+R has been tramsmitted and ACK received
.equ
MR_SLA_NACK
=$48
;SLA+R has been tramsmitted and NACK received
.equ
MR_DATA_ACK
=$50
;Data byte has been received and ACK returned
.equ
MR_DATA_NACK
=$58
;Data byte has been received and NACK
; tramsmitted
;***** Slave Transmitter staus codes *****
100
.equ
ST_SLA_ACK
.equ
ST_ARB_LOST_SLA_ACK=$B0;Arbitration lost in SLA+R/W as Master. Own
; SLA+W has been received and ACK returned
=$A8
.equ
ST_DATA_ACK
=$B8
;Own SLA+R has been received and ACK returned
;Data byte has been tramsmitted and ACK
;received
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
.equ
ST_DATA_NACK
=$C0
;Data byte has been tramsmitted and NACK
;received
.equ
ST_LAST_DATA
=$C8
;Last byte in I2DR has been transmitted (TWEA =
;’0’), ACK has been received
;***** Slave Receiver staus codes *****
.equ
SR_SLA_ACK
.equ
SR_ARB_LOST_SLA_ACK=$68;Arbitration lost in SLA+R/W as Master. Own
;SLA+R has been received and ACK returned
=$60
.equ
SR_GCALL_ACK
.equ
SR_ARB_LOST_GCALL_ACK=$78;Arbitration lost in SLA+R/W as Master.
;General Call has been received and ACK
;returned
.equ
SR_DATA_ACK
=$80
;Previously addressed with own SLA+W. Data byte
;has been received and ACK returned
.equ
SR_DATA_NACK
=$88
;Previously addressed with own SLA+W. Data byte
;has been received and NACK returned
.equ
SR_GCALL_DATA_ACK=$90;Previously addressed with General Call.Data
;byte has been received and ACK returned
.equ
SR_GCALL_DATA_NACK=$98;Previously addressed with General Call. Data
;byte has been received and NACK returned
.equ
SR_STOP
=$70
=$A0
;SLA+R has been received and ACK returned
;Generall call has been received and ACK
;returned
;A STOP condition or repeated START condition
;has been received while still addressed as a
;slave
;***** Miscellanous States *****
.equ
NO_INFO
=$F8
;No relevant state information; TWINT = ’0’
.equ
BUS_ERROR
=$00
;Bus error due to illegal START or STOP
;condition
101
1142E–AVR–02/03
The Analog
Comparator
The Analog Comparator compares the input values on the positive pin PB2 (AIN0) and
negative pin PB3 (AIN1). When the voltage on the positive pin PB2 (AIN0) is higher than
the voltage on the negative pin PB3 (AIN1), the Analog Comparator Output, ACO, is set
(one). The comparator’s output can be set to trigger the Timer/Counter1 Input Capture
function. In addition, the comparator can trigger a separate interrupt, exclusive to the
Analog Comparator. The user can select Interrupt triggering on comparator output rise,
fall or toggle. A block diagram of the comparator and its surrounding logic is shown in
Figure 56.
Figure 56. Analog Comparator Block Diagram
BANDGAP
REFERENCE
ACBG
ACME
ADEN
ADC MULTIPLEXER
OUTPUT 1)
Note:
The Analog Comparator
Control And Status Register –
ACSR
1. See Figure 57 on page 106.
Bit
7
6
5
4
3
2
1
0
$08 ($28)
ACD
ACBG
ACO
ACI
ACIE
ACIC
ACIS1
ACIS0
Read/Write
R/W
R/W
R
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
N/A
0
0
0
0
0
ACSR
• Bit 7 – ACD: Analog Comparator Disable
When this bit is set(one), the power to the Analog Comparator is switched off. This bit
can be set at any time to turn off the Analog Comparator. This will reduce power consumption in active and Idle mode. When changing the ACD bit, the Analog Comparator
Interrupt must be disabled by clearing the ACIE bit in ACSR. Otherwise an interrupt can
occur when the bit is changed.
• Bit 6 – ACBG: Analog Comparator Bandgap Select
When this bit is set and the BOD is enabled (BODEN Fuse is programmed), a fixed
bandgap voltage of nominally 1.22V replaces the positive input to the Analog Comparator. When this bit is cleared, AIN0 is applied to the positive input of the Analog
Comparator.
102
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
• Bit 5 – ACO: Analog Comparator Output
ACO is directly connected to the comparator output.
• Bit 4 – ACI: Analog Comparator Interrupt Flag
This bit is set (one) when a comparator output event triggers the Interrupt mode defined
by ACIS1 and ACIS0. The Analog Comparator Interrupt routine is executed if the ACIE
bit is set (one) and the I-bit in SREG is set (one). ACI is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, ACI is cleared by
writing a logic one to the flag.
• Bit 3 – ACIE: Analog Comparator Interrupt Enable
When the ACIE bit is set (one) and the I-bit in the Status Register is set (one), the Analog Comparator interrupt is activated. When cleared (zero), the interrupt is disabled.
• Bit 2 – ACIC: Analog Comparator Input Capture Enable
When set (one), this bit enables the Input Capture function in Timer/Counter1 to be triggered by the Analog Comparator. The comparator output is in this case directly
connected to the Input Capture front-end logic, making the comparator utilize the noise
canceler and edge select features of the Timer/Counter1 Input Capture interrupt. When
cleared (zero), no connection between the Analog Comparator and the Input Capture
function is given. To make the comparator trigger the Timer/Counter1 Input Capture
interrupt, the TICIE1 bit in the Timer Interrupt Mask Register (TIMSK) must be set (one).
• Bits 1, 0 – ACIS1, ACIS0: Analog Comparator Interrupt Mode Select
These bits determine which comparator events that trigger the Analog Comparator interrupt. The different settings are shown in Table 37.
Table 37. ACIS1/ACIS0 Settings
ACIS1
ACIS0
Interrupt Mode
0
0
Comparator Interrupt on Output Toggle
0
1
Reserved
1
0
Comparator Interrupt on Falling Output Edge
1
1
Comparator Interrupt on Rising Output Edge
When changing the ACIS1/ACIS0 bits, The Analog Comparator Interrupt must be disabled by clearing its Interrupt Enable bit in the ACSR Register. Otherwise an interrupt
can occur when the bits are changed.
103
1142E–AVR–02/03
Analog Comparator
Multiplexed Input
It is possible to select any of the PA7..0 (ADC7..0) pins to replace the negative input to
the Analog Comparator. The ADC multiplexer is used to select this input, and consequently, the ADC must be switched off to utilize this feature. If the Analog Comparator
Multiplexer Enable bit (ACME in SFIOR) is set (one) and the ADC is switched off (ADEN
in ADCSR is zero), MUX2..0 in ADMUX select the input pin to replace the negative input
to the Analog Comparator, as shown in Table 38. If ACME is cleared (zero) or ADEN is
set (one), PB3 (AIN1) is applied to the negative input to the Analog Comparator.
Table 38. Analog Comparator Multiplexed Input
104
ACME
ADEN
MUX2..0
Analog Comparator Negative Input
0
x
xxx
AIN1
1
1
xxx
AIN1
1
0
000
ADC0
1
0
001
ADC1
1
0
010
ADC2
1
0
011
ADC3
1
0
100
ADC4
1
0
101
ADC5
1
0
110
ADC6
1
0
111
ADC7
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Analog to Digital
Converter
Feature List
•
•
•
•
•
•
•
•
•
•
•
•
•
10-bit Resolution
0.5 LSB Integral Non-linearity
±2 LSB Absolute Accuracy
65 - 260 µs Conversion Time
Up to 15 kSPS at Maximum Resolution
Up to 76 kSPS at 8-bit Resolution
Eight Multiplexed Single Ended Input Channels
Optional Left Adjustment for ADC Result Readout
0 - V CC ADC Input Voltage Range
Selectable 2.56V ADC Reference Voltage
Free Run or Single Conversion Mode
Interrupt on ADC Conversion Complete
Sleep Mode Noise Canceler
The ATmega163 features a 10-bit successive approximation ADC. The ADC is connected to an 8-channel Analog Multiplexer which allows each pin of Port A to be used as
input for the ADC.
The ADC contains a Sample and Hold Amplifier which ensures that the input voltage to
the ADC is held at a constant level during conversion. A block diagram of the ADC is
shown in Figure 57.
The ADC has two separate analog supply voltage pins, AVCC and AGND. AGND must
be connected to GND, and the voltage on AVCC must not differ more than ±0.3V from
VCC. See the paragraph ADC Noise Canceling Techniques on how to connect these
pins.
Internal reference voltages of nominally 2.56V or AVCC are provided On-chip. The
2.56V reference may be externally decoupled at the AREF pin by a capacitor for better
noise perfomance. See “Internal Voltage Reference” on page 29 for a description of the
internal voltage reference.
105
1142E–AVR–02/03
Figure 57. Analog to Digital Converter Block Schematic
ADC CONVERSION
COMPLETE IRQ
ADC[9:0]
ADPS1
0
ADC DATA REGISTER
(ADCH/ADCL)
ADPS0
ADPS2
ADIF
ADFR
ADEN
ADSC
MUX1
15
ADC CTRL. & STATUS
REGISTER (ADCSR)
MUX0
MUX2
MUX4
MUX3
REFS0
ADLAR
REFS1
ADC MULTIPLEXER
SELECT (ADMUX)
ADIE
ADIF
8-BIT DATA BUS
PRESCALER
CHANNEL SELECTION
MUX DECODER
AVCC
CONVERSION LOGIC
INTERNAL 2.56 V
REFERENCE
SAMPLE & HOLD
COMPARATOR
AREF
10-BIT DAC
+
AGND
1.22 V BANDGAP
REFERENCE
ADC7
ADC6
ADC5
INPUT
MUX
ADC MULTIPLEXER
OUTPUT
ADC4
ADC3
ADC2
ADC1
ADC0
Operation
The ADC converts an analog input voltage to a 10-bit digital value through successive
approximation. The minimum value represents AGND and the maximum value represents the voltage on the AREF pin minus 1 LSB. Optionally, AVCC or an internal 2.56V
reference voltage may be connected to the AREF pin by writing to the REFSn bits in the
ADMUX Register. The internal voltage reference may thus be decoupled by an external
capacitor at the AREF pin to improve noise immunity.
The analog input channel is selected by writing to the MUX bits in ADMUX. Any of the
eight ADC input pins ADC7..0, as well as AGND and a fixed bandgap voltage reference
of nominally 1.22V (VBG), can be selected as single ended inputs to the ADC.
The ADC can operate in two modes – Single Conversion and Free Running mode. In
Single Conversion mode, each conversion will have to be initiated by the user. In Free
Running mode, the ADC is constantly sampling and updating the ADC Data Register.
The ADFR bit in ADCSR selects between the two available modes.
The ADC is enabled by setting the ADC Enable bit, ADEN in ADCSR. Voltage reference
and input channel selections will not go into effect until ADEN is set. The ADC does not
106
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
consume power when ADEN is cleared, so it is recommended to switch off the ADC
before entering power saving sleep modes.
A conversion is started by writing a logical one to the ADC Start Conversion bit, ADSC.
This bit stays high as long as the conversion is in progress and will be set to zero by
hardware when the conversion is completed. If a different data channel is selected while
a conversion is in progress, the ADC will finish the current conversion before performing
the channel change.
The ADC generates a 10-bit result, which are presented in the ADC Data Registers,
ADCH and ADCL. By default, the result is presented right adjusted, but can optionally
be presented left adjusted by setting the ADLAR bit in ADMUX.
If the result is left adjusted and no more than 8-bit precision is required, it is sufficient to
read ADCH. Otherwise, ADCL must be read first, then ADCH, to ensure that the content
of the Data Registers belongs to the same conversion. Once ADCL is read, ADC access
to Data Registers is blocked. This means that if ADCL has been read, and a conversion
completes before ADCH is read, neither register is updated and the result from the conversion is lost. When ADCH is read, ADC access to the ADCH and ADCL Registers is
re-enabled.
The ADC has its own interrupt which can be triggered when a conversion completes.
When ADC access to the Data Registers is prohibited between reading of ADCH and
ADCL, the interrupt will trigger even if the result is lost.
Prescaling and
Conversion Timing
Figure 58. ADC Prescaler
ADEN
Reset
7-BIT ADC PRESCALER
CK/64
CK/128
CK/32
CK/8
CK/16
CK/4
CK/2
CK
ADPS0
ADPS1
ADPS2
ADC CLOCK SOURCE
The successive approximation circuitry requires an input clock frequency between 50
kHz and 200 kHz to achieve maximum resolution. If a lower resolution than 10 bits is
required, the input clock frequency to the ADC can be higher than 200 kHz to achieve a
higher sampling rate. See “ADC Characteristics” on page 114 for more details. The ADC
module contains a prescaler, which divides the system clock to an acceptable ADC
clock frequency.
The ADPS bits in ADCSR are used to generate a proper ADC clock input frequency
from any XTAL frequency above 100 kHz. The prescaler starts counting from the
moment the ADC is switched on by setting the ADEN bit in ADCSR. The prescaler
keeps running for as long as the ADEN bit is set, and is continuously reset when ADEN
is low.
107
1142E–AVR–02/03
When initiating a conversion by setting the ADSC bit in ADCSR, the conversion starts at
the following rising edge of the ADC clock cycle.
A normal conversion takes 13 ADC clock cycles. In certain situations, the ADC needs
more clock cycles to initalization and minimize offset errors. Extended conversions take
25 ADC clock cycles and occur as the first conversion after the ADC is switched on
(ADEN in ADCSR is set). Additionally, when changing voltage reference, the user may
improve accuracy by disregarding the first conversion result after the reference or MUX
setting was changed.
The actual sample-and-hold takes place 1.5 ADC clock cycles after the start of a normal
conversion and 13.5 ADC clock cycles after the start of an extended conversion. When
a conversion is complete, the result is written to the ADC Data Registers, and ADIF is
set. In Single Conversion mode, ADSC is cleared simultaneously. The software may
then set ADSC again, and a new conversion will be initated on the first rising ADC clock
edge. In Free Running mode, a new conversion will be started immediately after the
conversion completes, while ADSC remains high. Using Free Running mode and an
ADC clock frequency of 200 kHz gives the lowest conversion time with a maximum resolution, 65 µs, equivalent to 15 kSPS. For a summary of conversion times, see Table
39.
Figure 59. ADC Timing Diagram, Extended Conversion (Single Conversion Mode)
Next
Conversion
Extended Conversion
Cycle Number
1
2
12
13
14
15
16
17
18
19
20
21
22
23
24
25
1
2
3
ADC Clock
ADEN
ADSC
ADIF
ADCH
Sign and MSB of Result
ADCL
LSB of Result
MUX and REFS
update
Conversion
Complete
Sample & Hold
MUX and REFS
Update
Figure 60. ADC Timing Diagram, Single Conversion
One Conversion
Cycle Number
1
2
3
4
5
6
7
8
9
Next Conversion
10
11
12
13
1
2
3
ADC Clock
ADSC
ADIF
ADCH
Sign and MSB of Result
ADCL
LSB of Result
Sample & Hold
MUX and REFS
Update
108
Conversion
Complete
MUX and REFS
Update
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Figure 61. ADC Timing Diagram, Free Run Conversion
One Conversion
Cycle Number
11
12
Next Conversion
13
1
2
3
4
ADC Clock
ADSC
ADIF
ADCH
Sign and MSB of Result
ADCL
LSB of Result
Conversion
Complete
Sample & Hold
MUX and REFS
Update
Table 39. ADC Conversion Time
Sample & Hold (Cycles
from Start of
Conversion)
Conversion Time
(Cycles)
Extended Conversion
13.5
25
125 - 500
Normal Conversions
1.5
13
65 - 260
Condition
ADC Noise Canceler
Function
Conversion Time
(µs)
The ADC features a Noise Canceler that enables conversion during ADC Noise Reduction mode (see “Sleep Modes” on page 35) to reduce noise induced from the CPU core
and other I/O peripherals. If other I/O peripherals must be active during conversion, this
mode works equivalently for Idle mode. To make use of this feature, the following procedure should be used:
1. Make sure that the ADC is enabled and is not busy converting. Single Conversion Mode must be selected and the ADC conversion complete interrupt must be
enabled.
ADEN = 1
ADSC = 0
ADFR = 0
ADIE = 1
2. Enter ADC Noise Reduction mode (or Idle mode). The ADC will start a conversion once the CPU has been halted.
3. If no other interrupts occur before the ADC conversion completes, the ADC interrupt will wake up the CPU and execute the ADC Conversion Complete interrupt
routine.
109
1142E–AVR–02/03
The ADC Multiplexer Selection
Register – ADMUX
Bit
7
6
5
4
3
2
1
0
REFS1
REFS0
ADLAR
MUX4
MUX3
MUX2
MUX1
MUX0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
$07 ($27)
ADMUX
• Bit 7, 6 – REFS1..0: Reference Selection Bits
These bits select the voltage reference for the ADC, as shown in Table 17. If these bits
are changed during a conversion, the change will not go in effect until this conversion is
complete (ADIF in ADCSR is set). The user should disregard the first conversion result
after changing these bits to obtain maximum accuracy. The internal voltage reference
options may not be used if an external reference voltage is being applied to the AREF
pin.
Table 40. Voltage Reference Selections for ADC
•
REFS1
REFS0
Voltage Reference Selection
0
0
AREF, Internal Vref turned off
0
1
AVCC with external capacitor at AREF pin
1
0
Reserved
1
1
Internal 2.56V Voltage Reference with external capacitor at AREF pin
Bit 5 – ADLAR: ADC Left Adjust Result
The ADLAR bit affects the presentation of the ADC conversion result in the ADC Data
Register. If ADLAR is cleared, the result is right adjusted. If ADLAR is set, the result is
left adjusted. Changing the ADLAR bit will affect the ADC Data Register immediately,
regardless of any ongoing conversions. For a complete description of this bit, see “The
ADC Data Register – ADCL and ADCH” on page 112.
• Bits 4..0 – MUX4..MUX0: Analog Channel and Gain Selection Bits
The value of these bits selects which combination of analog inputs are connected to the
ADC. See Table 41 for details. If these bits are changed during a conversion, the
change will not go in effect until this conversion is complete (ADIF in ADCSR is set).
Table 41. Input Channel Selections
110
MUX4..0
Single-ended Input
00000
ADC0
00001
ADC1
00010
ADC2
00011
ADC3
00100
ADC4
00101
ADC5
00110
ADC6
00111
ADC7
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Table 41. Input Channel Selections (Continued)
The ADC Control and Status
Register – ADCSR
MUX4..0
Single-ended Input
01000..11101
Reserved
11110
1.22V (VBG)
11111
0V (AGND)
Bit
7
6
5
4
3
2
1
0
ADEN
ADSC
ADFR
ADIF
ADIE
ADPS2
ADPS1
ADPS0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
$06 ($26)
ADCSR
• Bit 7 – ADEN: ADC Enable
Writing a logical “1” to this bit enables the ADC. By clearing this bit to zero, the ADC is
turned off. Turning the ADC off while a conversion is in progress, will terminate this
conversion.
• Bit 6 – ADSC: ADC Start Conversion
In Single Conversion mode, a logical “1” must be written to this bit to start each conversion. In Free Running mode, a logical “1” must be written to this bit to start the first
conversion. The first time ADSC has been written after the ADC has been enabled, or if
ADSC is written at the same time as the ADC is enabled, an extended conversion will
precede the initiated conversion. This extended conversion performs initialization of the
ADC.
ADSC will read as one as long as a conversion is in progress. When the conversion is
complete, it returns to zero. When a extended conversion precedes a real conversion,
ADSC will stay high until the real conversion completes. Writing a 0 to this bit has no
effect.
• Bit 5 – ADFR: ADC Free Running Select
When this bit is set (one) the ADC operates in Free Running mode. In this mode, the
ADC samples and updates the Data Registers continuously. Clearing this bit (zero) will
terminate Free Running mode.
• Bit 4 – ADIF: ADC Interrupt Flag
This bit is set (one) when an ADC conversion completes and the Data Registers are
updated. The ADC Conversion Complete Interrupt is executed if the ADIE bit and the Ibit in SREG are set (one). ADIF is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, ADIF is cleared by writing a logical one to the
flag. Beware that if doing a Read-Modify-Write on ADCSR, a pending interrupt can be
disabled. This also applies if the SBI and CBI instructions are used.
• Bit 3 – ADIE: ADC Interrupt Enable
When this bit is set (one) and the I-bit in SREG is set (one), the ADC Conversion Complete Interrupt is activated.
111
1142E–AVR–02/03
• Bits 2..0 – ADPS2..0: ADC Prescaler Select Bits
These bits determine the division factor between the XTAL frequency and the input
clock to the ADC.
Table 42. ADC Prescaler Selections
ADPS2
ADPS1
ADPS0
Division Factor
0
0
0
2
0
0
1
2
0
1
0
4
0
1
1
8
1
0
0
16
1
0
1
32
1
1
0
64
1
1
1
128
The ADC Data Register –
ADCL and ADCH
ADLAR = 0
Bit
15
14
13
12
11
10
9
8
$05 ($25)
SIGN
–
–
–
–
–
ADC9
ADC8
ADCH
$04 ($24)
ADC7
ADC6
ADC5
ADC4
ADC3
ADC2
ADC1
ADC0
ADCL
7
6
5
4
3
2
1
0
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Read/Write
Initial Value
ADLAR = 1
Bit
15
14
13
12
11
10
9
8
$05 ($25)
ADC9
ADC8
ADC7
ADC6
ADC5
ADC4
ADC3
ADC2
ADCH
$04 ($24)
ADC1
ADC0
–
–
–
–
–
–
ADCL
7
6
5
4
3
2
1
0
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Read/Write
Initial Value
When an ADC conversion is complete, the result is found in these two registers.
When ADCL is read, the ADC Data Register is not updated until ADCH is read. Consequently, if the result is left adjusted and no more than 8-bit precision is required, it is
sufficient to read ADCH. Otherwise, ADCL must be read first, then ADCH.
The ADLAR bit in ADMUX affects the way the result is read from the registers. If ADLAR
is set, the result is left adjusted. If ADLAR is cleared (default), the result is right adjusted.
• ADC9..0: ADC Conversion result
These bits represent the result from the conversion. $000 represents analog ground,
and $3FF represents the selected reference voltage minus one LSB.
112
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Scanning Multiple
Channels
Since change of analog channel always is delayed until a conversion is finished, the
Free Running mode can be used to scan multiple channels without interrupting the converter. Typically, the ADC Conversion Complete interrupt will be used to perform the
channel shift. However, the user should take the following fact into consideration:
The interrupt triggers once the result is ready to be read. In Free Running mode, the
next conversion will start immediately when the interrupt triggers. If ADMUX is changed
after the interrupt triggers, the next conversion has already started, and the old setting is
used.
ADC Noise Canceling
Techniques
Digital circuitry inside and outside the ATmega163 generates EMI which might affect the
accuracy of analog measurements. If conversion accuracy is critical, the noise level can
be reduced by applying the following techniques:
1. The analog part of the ATmega163 and all analog components in the application
should have a separate analog ground plane on the PCB. This ground plane is
connected to the digital ground plane via a single point on the PCB.
2. Keep analog signal paths as short as possible. Make sure analog tracks run over
the analog ground plane, and keep them well away from high-speed switching
digital tracks.
3. The AVCC pin on the ATmega163 should be connected to the digital VCC supply
voltage via an LC network as shown in Figure 62.
4. Use the ADC noise canceler function to reduce induced noise from the CPU.
5. If some Port A pins are used as digital outputs, it is essential that these do not
switch while a conversion is in progress.
PA3 (ADC3)
35
34
Analog Ground Plane
PA2 (ADC2)
36
33
PA4 (ADC4)
32
PA5 (ADC5)
31
PA6 (ADC6)
30
PA7 (ADC7)
29
AREF
28
27
26
AGND
AVCC
10µΗ
PA1 (ADC1)
37
100nF
PA0 (ADC0)
38
ATmega163
39
VCC
GND
Figure 62. ADC Power Connections
PC7 (TOSC2)
113
1142E–AVR–02/03
ADC Characteristics
Table 43. ADC Characteristics
Symbol
Parameter
Condition
Resolution
Single-ended Conversion
10
Absolute accuracy
VREF = 4V
ADC clock = 200 kHz
1
Absolute accuracy
VREF = 4V
ADC clock = 1 MHz
4
LSB
Absolute accuracy
VREF = 4V
ADC clock = 2 MHz
16
LSB
Integral Non-linearity
VREF > 2V
0.5
LSB
Differential Non-linearity
VREF > 2V
0.5
LSB
Zero Error (Offset)
VREF > 2V
1
LSB
Conversion Time
Free Running Conversion
Clock Frequency
Min
65
Analog Supply Voltage
VREF
Reference Voltage
2V
VINT
Internal Voltage Reference
2.35
VBG
Bandgap Voltage Reference
RREF
Reference Input Resistance
RAIN
Notes:
114
Input Voltage
Analog Input Resistance
VCC - 0.3
Max
Units
Bits
2
LSB
260
50
AVCC
VIN
Typ
µs
200
(1)
VCC + 0.3
kHz
(2)
V
AVCC
V
2.56
2.77
V
1.12
1.22
1.32
V
6
10
13
kΩ
AREF
V
AGND
100
MΩ
1. Minimum for AVCC is 2.7V.
2. Maximum for AVCC is 5.5V.
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
I/O Ports
All AVR ports have true Read-Modify-Write functionality when used as general digital
I/O ports. This means that the direction of one port pin can be changed without unintentionally changing the direction of any other pin with the SBI and CBI instructions. The
same applies for changing drive value (if configured as output) or enabling/disabling of
pull-up resistors (if configured as input).
Port A
Port A is an 8-bit bi-directional I/O port with internal pull-ups.
Three I/O memory address locations are allocated for Port A, one each for the Data
Register – PORTA, $1B($3B), Data Direction Register – DDRA, $1A($3A) and the Port
A Input Pins – PINA, $19($39). The Port A Input Pins address is read only, while the
Data Register and the Data Direction Register are read/write.
All port pins have individually selectable pull-up resistors. The PORT A output buffers
can sink 20 mA and thus drive LED displays directly. When pins PA0 to PA7 are used as
inputs and are externally pulled low, they will source current if the internal pull-up resistors are activated.
Port A has an alternate function as analog inputs for the ADC. If some Port A pins are
configured as outputs, it is essential that these do not switch when a conversion is in
progress. This might corrupt the result of the conversion.
During Power-down mode, the schmitt trigger of the digital input is disconnected. This
allows analog signals that are close to VCC/2 to be present during powerdown without
causing excessive power consumption.
The Port A Data Register –
PORTA
The Port A Data Direction
Register – DDRA
The Port A Input Pins Address
– PINA
Bit
7
6
5
4
3
2
1
0
$1B ($3B)
PORTA7
PORTA6
PORTA5
PORTA4
PORTA3
PORTA2
PORTA1
PORTA0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
$1A ($3A)
DDA7
DDA6
DDA5
DDA4
DDA3
DDA2
DDA1
DDA0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
PINA7
PINA6
PINA5
PINA4
PINA3
PINA2
PINA1
PINA0
Read/Write
R
R
R
R
R
R
R
R
Initial Value
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
$19 ($39)
PORTA
DDRA
PINA
The Port A Input Pins Address – PINA – is not a register, and this address enables
access to the physical value on each Port A pin. When reading PORTA the PORTA
Data Latch is read, and when reading PINA, the logical values present on the pins are
read.
PORT A as General Digital I/O
All 8 bits in PORT A are equal when used as digital I/O pins.
PAn, General I/O pin: The DDAn bit in the DDRA Register selects the direction of this
pin, if DDAn is set (one), PAn is configured as an output pin. If DDAn is cleared (zero),
PAn is configured as an input pin. If PORTAn is set (one) when the pin configured as an
input pin, the MOS pull up resistor is activated. To switch the pull up resistor off, the
PORTAn has to be cleared (zero), the pin has to be configured as an output pin, or the
115
1142E–AVR–02/03
PUD bit has to be set. The Port A pins are tri-stated when a reset condition becomes
active, even if the clock is not running.
Table 44. DDAn Effects on PORTA Pins(1)
DDAn
PORTAn
PUD
I/O
Pull Up
0
0
x
Input
No
Tri-state (Hi-Z)
0
1
1
Input
No
Tri-state (Hi-Z)
0
1
0
Input
Yes
PAn will source current if ext. pulled low.
1
0
x
Output
No
Push-pull Zero Output
1
1
x
Output
No
Push-pull One Output
Note:
PORT A Schematics
Comment
1. n: 7,6…0, pin number.
Note that all port pins are synchronized. The synchronization latches are not shown in
the figure.
Figure 63. PORTA Schematic Diagrams (Pins PA0 - PA7)
RD
MOS
PULLUP
PUD
RESET
Q
D
DDAn
WD
RESET
Q
D
PORTAn
C
PDn
RL
PWRDN
WP
RP
TO ADC MUX
WP:
WD:
RL:
RP:
RD:
n:
PUD:
116
DATA BUS
C
ADCn
WRITE PORTA
WRITE DDRA
READ PORTA LATCH
READ PORTA PIN
READ DDRA
0-7
PULL-UP DISABLE
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Port B
Port B is an 8-bit bi-directional I/O port with internal pull-ups.
Three I/O memory address locations are allocated for Port B, one each for the Data
Register – PORTB, $18($38), Data Direction Register – DDRB, $17($37) and the Port B
Input Pins – PINB, $16($36). The Port B Input Pins address is read only, while the Data
Register and the Data Direction Register are read/write.
All port pins have individually selectable pull-up resistors. The Port B output buffers can
sink 20 mA and thus drive LED displays directly. When pins PB0 to PB7 are used as
inputs and are externally pulled low, they will source current if the internal pull-up resistors are activated.
The Port B pins with alternate functions are shown in Table 45.
Table 45. Port B Pins Alternate Functions
Port Pin
Alternate Functions
PB0
T0 (Timer/Counter0 External Counter Input)
PB1
T1 (Timer/Counter1 External Counter Input)
PB2
AIN0 (Analog Comparator Positive Input)
PB3
AIN1 (Analog Comparator Negative Input)
PB4
SS (SPI Slave Select Input)
PB5
MOSI (SPI Bus Master Output/Slave Input)
PB6
MISO (SPI Bus Master Input/Slave Output)
PB7
SCK (SPI Bus Serial Clock)
When the pins are used for the alternate function, the DDRB and PORTB Registers
have to be set according to the alternate function description.
The Port B Data Register –
PORTB
Bit
7
6
5
4
3
2
1
0
PORTB7
PORTB6
PORTB5
PORTB4
PORTB3
PORTB2
PORTB1
PORTB0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
$18 ($38)
The Port B Data Direction
Register – DDRB
Bit
7
6
5
4
3
2
1
0
DDB7
DDB6
DDB5
DDB4
DDB3
DDB2
DDB1
DDB0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
$17 ($37)
The Port B Input Pins Address
– PINB
Bit
7
6
5
4
3
2
1
0
PINB7
PINB6
PINB5
PINB4
PINB3
PINB2
PINB1
PINB0
Read/Write
R
R
R
R
R
R
R
R
Initial Value
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
$16 ($36)
PORTB
DDRB
PINB
The Port B Input Pins Address – PINB – is not a register, and this address enables
access to the physical value on each Port B pin. When reading PORTB, the PORTB
Data Latch is read, and when reading PINB, the logical values present on the pins are
read.
117
1142E–AVR–02/03
Port B As General Digital I/O
All eight bits in Port B are equal when used as digital I/O pins. PBn, General I/O pin: The
DDBn bit in the DDRB Register selects the direction of this pin, if DDBn is set (one), PBn
is configured as an output pin. If DDBn is cleared (zero), PBn is configured as an input
pin. If PORTBn is set (one) when the pin configured as an input pin, the MOS pull up
resistor is activated. To switch the pull up resistor off, the PORTBn has to be cleared
(zero), the pin has to be configured as an output pin, or the PUD bit has to be set. The
Port B pins are tri-stated when a reset condition becomes active, even if the clock is not
running.
Table 46. DDBn Effects on Port B Pins(1)
DDBn
PORTBn
PUD
I/O
Pull Up
0
0
x
Input
No
Tri-state (Hi-Z)
0
1
1
Input
No
Tri-state (Hi-Z)
0
1
0
Input
Yes
PBn will source current if ext. pulled low.
1
0
x
Output
No
Push-pull Zero Output
1
1
x
Output
No
Push-pull One Output
Note:
Alternate Functions Of
PORTB
Comment
1. n: 7,6…0, pin number.
The alternate pin configuration is as follows:
• SCK – PORTB, Bit 7
SCK: Master Clock output, Slave Clock input pin for SPI channel. When the SPI is
enabled as a Slave, this pin is configured as an input regardless of the setting of DDB7.
When the SPI is enabled as a Master, the data direction of this pin is controlled by
DDB7. When the pin is forced to be an input, the pull-up can still be controlled by the
PORTB7 bit. See the description of the SPI port for further details.
• MISO – PORTB, Bit 6
MISO: Master Data input, Slave Data output pin for SPI channel. When the SPI is
enabled as a Master, this pin is configured as an input regardless of the setting of
DDB6. When the SPI is enabled as a Slave, the data direction of this pin is controlled by
DDB6. When the pin is forced to be an input, the pull-up can still be controlled by the
PORTB6 bit. See the description of the SPI port for further details.
• MOSI – PORTB, Bit 5
MOSI: SPI Master Data output, Slave Data input for SPI channel. When the SPI is
enabled as a Slave, this pin is configured as an input regardless of the setting of DDB5.
When the SPI is enabled as a Master, the data direction of this pin is controlled by
DDB5. When the pin is forced to be an input, the pull-up can still be controlled by the
PORTB5 bit. See the description of the SPI port for further details.
• SS – PORTB, Bit 4
SS: Slave Port Select input. When the SPI is enabled as a Slave, this pin is configured
as an input regardless of the setting of DDB4. As a slave, the SPI is activated when this
pin is driven low. When the SPI is enabled as a Master, the data direction of this pin is
controlled by DDB4. When the pin is forced to be an input, the pull-up can still be controlled by the PORTB4 bit. See the description of the SPI port for further details.
118
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
• AIN1 – PORTB, Bit 3
AIN1, Analog Comparator Negative input. When configured as an input (DDB3 is
cleared (zero)) and with the internal MOS pull up resistor switched off (PB3 is cleared
(zero)), this pin also serves as the negative input of the On-chip Analog Comparator.
During Power-down mode, the schmitt trigger of the digital input is disconnected. This
allows analog signals which are close to VCC/2 to be present during Power-down without
causing excessive power consumption.
• AIN0 – PORTB, Bit 2
AIN0, Analog Comparator Positive input. When configured as an input (DDB2 is cleared
(zero)) and with the internal MOS pull up resistor switched off (PB2 is cleared (zero)),
this pin also serves as the positive input of the On-chip Analog Comparator. During
Power-down mode, the schmitt trigger of the digital input is disconnected. This allows
analog signals which are close to VCC/2 to be present during Power-down without causing excessive power consumption.
• T1 – PORTB, Bit 1
T1, Timer/Counter1 Counter Source. See the Timer description for further details.
• T0 – PORTB, Bit 0
T0: Timer/Counter0 Counter Source. See the Timer description for further details.
Port B Schematics
Note that all port pins are synchronized. The synchronization latches are not shown in
the figures.
Figure 64. PORTB Schematic Diagram (Pins PB0 and PB1)
PUD
PUD: PULL-UP DISABLE
2
119
1142E–AVR–02/03
Figure 65. PORTB Schematic Diagram (Pins PB2 and PB3)
RD
MOS
PULLUP
PUD
RESET
Q
D
DDBn
WD
RESET
Q
D
PORTBn
C
PBn
RL
WP
RP
PWRDN
AINm
TO COMPARATOR
WP:
WD:
RL:
RP:
RD:
n:
m:
PUD:
DATA BUS
C
WRITE PORTB
WRITE DDRB
READ PORTB LATCH
READ PORTB PIN
READ DDRB
2, 3
0, 1
PULL-UP DISABLE
Figure 66. PORTB Schematic Diagram (Pin PB4)
RD
MOS
PULLUP
PUD
RESET
Q
D
DDB4
WD
RESET
Q
D
PORTB4
C
PB4
RL
DATA BUS
C
WP
RP
WP:
WD:
RL:
RP:
RD:
MSTR:
SPE:
PUD:
120
WRITE PORTB
WRITE DDRB
READ PORTB LATCH
READ PORTB PIN
READ DDRB
SPI MASTER ENABLE
SPI ENABLE
PULL-UP DISABLE
MSTR
SPE
SPI SS
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Figure 67. PORTB Schematic Diagram (Pin PB5)
RD
MOS
PULLUP
PUD
RESET
Q
R
D
DDB5
C
DATA BUS
WD
RESET
R
Q
D
PORTB5
PB5
C
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
SPE:
MSTR:
PUD:
WRITE PORTB
WRITE DDRB
READ PORTB LATCH
READ PORTB PIN
READ DDRB
SPI ENABLE
MASTER SELECT
PULL-UP DISABLE
MSTR
SPE
SPI MASTER
OUT
SPI SLAVE
IN
Figure 68. PORTB Schematic Diagram (Pin PB6)
RD
MOS
PULLUP
PUD
RESET
Q
R
D
DDB6
WD
RESET
R
Q
D
PORTB6
PB6
DATA BUS
C
C
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
SPE:
MSTR
PUD:
WRITE PORTB
WRITE DDRB
READ PORTB LATCH
READ PORTB PIN
READ DDRB
SPI ENABLE
MASTER SELECT
PULL-UP DISABLE
MSTR
SPE
SPI SLAVE
OUT
SPI MASTER
IN
121
1142E–AVR–02/03
Figure 69. PORTB Schematic Diagram (Pin PB7)
RD
MOS
PULLUP
PUD
RESET
Q
R
D
DDB7
WD
RESET
R
Q
D
PORTB7
PB7
DATA BUS
C
C
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
SPE:
MSTR
PUD:
WRITE PORTB
WRITE DDRB
READ PORTB LATCH
READ PORTB PIN
READ DDRB
SPI ENABLE
MASTER SELECT
PULL-UP DISABLE
MSTR
SPE
SPI ClLOCK
OUT
SPI CLOCK
IN
122
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Port C
Port C is an 8-bit bi-directional I/O port with internal pull-ups.
Three I/O memory address locations are allocated for the Port C, one each for the Data
Register – PORTC, $15($35), Data Direction Register – DDRC, $14($34) and the Port C
Input Pins – PINC, $13($33). The Port C Input Pins address is read only, while the Data
Register and the Data Direction Register are read/write.
All port pins have individually selectable pull-up resistors. The PORT C output buffers
can sink 20 mA and thus drive LED displays directly. When pins PC0 to PC7 are used
as inputs and are externally pulled low, they will source current if the internal pull-up
resistors are activated.
Table 47. Port C Pins Alternate Functions
Port Pin
The Port C Data Register –
PORTC
PC0
SCL (Two-wire Serial Bus Clock Line)
PC1
SDA (Two-wire Serial Bus Data Input/Output Line)
PC6
TOSC1 (Timer Oscillator Pin 1)
PC7
TOSC2 (Timer Oscillator Pin 2)
Bit
7
6
5
4
3
2
1
0
PORTC7
PORTC6
PORTC5
PORTC4
PORTC3
PORTC2
PORTC1
PORTC0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
$15 ($35)
The Port C Data Direction
Register – DDRC
Bit
7
6
5
4
3
2
1
0
DDC7
DDC6
DDC5
DDC4
DDC3
DDC2
DDC1
DDC0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
$14 ($34)
The Port C Input Pins Address
– PINC
Alternate Function
Bit
7
6
5
4
3
2
1
0
PINC7
PINC6
PINC5
PINC4
PINC3
PINC2
PINC1
PINC0
Read/Write
R
R
R
R
R
R
R
R
Initial Value
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
$13 ($33)
PORTC
DDRC
PINC
The Port C Input Pins Address – PINC – is not a register, and this address enables
access to the physical value on each Port C pin. When reading PORTC, the PORTC
Data Latch is read, and when reading PINC, the logical values present on the pins are
read.
Port C as General Digital I/O
All eight bits in PORT C are equal when used as digital I/O pins.
PCn, General I/O pin: The DDCn bit in the DDRC Register selects the direction of this
pin, if DDCn is set (one), PCn is configured as an output pin. If DDCn is cleared (zero),
PCn is configured as an input pin. If PORTCn is set (one) when the pin configured as an
input pin, the MOS pull up resistor is activated. To switch the pull up resistor off,
PORTCn has to be cleared (zero), the pin has to be configured as an output pin, or the
PUD bit has to be set. The Port C pins are tri-stated when a reset condition becomes
active, even if the clock is not running.
123
1142E–AVR–02/03
Table 48. DDCn Effects on PORT C Pins(1)
DDCn
PORTCn
PUD
I/O
Pull Up
0
0
x
Input
No
Tri-state (Hi-Z)
0
1
1
Input
No
Tri-state (Hi-Z)
0
1
0
Input
Yes
PCn will source current if ext. pulled low.
1
0
x
Output
No
Push-pull Zero Output
1
1
x
Output
No
Push-pull One Output
Note:
Comment
1. n: 7…0, pin number
Alternate Functions of PORTC • TOSC2 – PORTC, Bit 7
TOSC2, Timer Oscillator pin 2: When the AS2 bit in ASSR is set (one) to enable asynchronous clocking of Timer/Counter2, pin PC7 is disconnected from the port, and
becomes the inverting output of the Oscillator amplifier. In this mode, a crystal Oscillator
is connected to this pin, and the pin can not be used as an I/O pin.
• TOSC1 – PORTC, Bit 6
TOSC1, Timer Oscillator pin 1: When the AS2 bit in ASSR is set (one) to enable asynchronous clocking of Timer/Counter1, pin PC6 is disconnected from the port, and
becomes the input of the inverting Oscillator amplifier. In this mode, a crystal Oscillator
is connected to this pin, and the pin can not be used as an I/O pin.
• SDA – PORTC, Bit 1
SDA, Two-wire Serial Bus Data: When the TWEN bit in TWCR is set (one) to enable the
Two-wire Serial Interface, pin PC1 is disconnected from the port and becomes the Serial
Data I/O pin for the Two-wire Serial Interface. In this mode, there is a spike filter on the
pin to capture spikes shorter than 50 ns on the input signal, and the pin is driven by an
open collector driver with slew rate limitation.
• SCL – PORTC, Bit 0
SCL, Two-wire Serial Interface Clock: When the TWEN bit in TWCR is set (one) to
enable the Two-wire Serial Interface, pin PC1 is disconnected from the port and
becomes the Serial Clock I/O pin for the Two-wire Serial Interface. In this mode, there is
a spike filter on the pin to capture spikes shorter than 50 ns on the input signal.
124
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Port C Schematics
Note that all port pins are synchronized. The synchronization latches are not shown in
the figure.
Figure 70. PORTC Schematic Diagram (Pins PC0 - PC1)
0
DDCn
PUD
PCn
1
n
0
1
SCL/SDA out
SCL/SDA in
TWEN
PUD: PULL-UP DISABLE
n = 0, 1
125
1142E–AVR–02/03
Figure 71. PORTC Schematic Diagram (Pins PC2 - PC5)
RD
MOS
PULLUP
PUD
RESET
R
Q
D
DDCn
C
DATA BUS
WD
RESET
R
Q
D
PORTCn
PCn
C
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
PUD:
n:
WRITE PORTC
WRITE DDRC
READ PORTC LATCH
READ PORTC PIN
READ DDRC
PULL-UP DISABLE
2..5
Figure 72. PORTC Schematic Diagram (Pins PC6)
RD
PUD
MOS
PULLUP
RESET
Q
R
D
DDC6
WD
RESET
R
Q
D
PORTC6
PC6
DATA BUS
C
C
RL
WP
RP
0
1
AS2
T/C2 OSC
AMP INPUT
WP:
WD:
RL:
RP:
RD:
AS2:
PUD:
126
WRITE PORTC
WRITE DDRC
READ PORTC LATCH
READ PORTC PIN
READ DDRC
ASYNCH SELECT T/C2
PULL-UP DISABLE
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Figure 73. PORTC Schematic Diagram (Pins PC7)
PUD
0
1
PUD: PULL-UP DISABLE
127
1142E–AVR–02/03
Port D
Port D is an 8 bit bi-directional I/O port with internal pull-up resistors.
Three I/O memory address locations are allocated for Port D, one each for the Data
Register – PORTD, $12($32), Data Direction Register – DDRD, $11($31) and the Port D
Input Pins – PIND, $10($30). The Port D Input Pins address is read only, while the Data
Register and the Data Direction Register are read/write.
The Port D output buffers can sink 20 mA. As inputs, Port D pins that are externally
pulled low will source current if the pull-up resistors are activated. Some Port D pins
have alternate functions as shown in Table 49.
Table 49. Port D Pins Alternate Functions
Port Pin
The Port D Data Register –
PORTD
PD0
RXD (UART Input Pin)
PD1
TXD (UART Output Pin)
PD2
INT0 (External Interrupt 0 Input)
PD3
INT1 (External Interrupt 1 Input)
PD4
OC1B (Timer/Counter1 Output CompareB Match Output)
PD5
OC1A (Timer/Counter1 Output CompareA Match Output)
PD6
ICP (Timer/Counter1 Input Capture Pin)
PD7
OC2 (Timer/Counter2 Output Compare Match Output)
Bit
7
6
5
4
3
2
1
0
PORTD7
PORTD6
PORTD5
PORTD4
PORTD3
PORTD2
PORTD1
PORTD0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
$12 ($32)
The Port D Data Direction
Register – DDRD
Bit
7
6
5
4
3
2
1
0
DDD7
DDD6
DDD5
DDD4
DDD3
DDD2
DDD1
DDD0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
$11 ($31)
The Port D Input Pins Address
– PIND
Alternate Function
Bit
7
6
5
4
3
2
1
0
PIND7
PIND6
PIND5
PIND4
PIND3
PIND2
PIND1
PIND0
Read/Write
R
R
R
R
R
R
R
R
Initial Value
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
$10 ($30)
PORTD
DDRD
PIND
The Port D Input Pins Address – PIND – is not a register, and this address enables
access to the physical value on each Port D pin. When reading PORTD, the PORTD
Data Latch is read, and when reading PIND, the logical values present on the pins are
read.
128
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Port D as General Digital I/O
PDn, General I/O pin: The DDDn bit in the DDRD Register selects the direction of this
pin. If DDDn is set (one), PDn is configured as an output pin. If DDDn is cleared (zero),
PDn is configured as an input pin. If PDn is set (one) when configured as an input pin
the MOS pull up resistor is activated. To switch the pull up resistor off the PDn has to be
cleared (zero), the pin has to be configured as an output pin, or the PUD bit has to be
set. The Port D pins are tri-stated when a reset condition becomes active, even if the
clock is not running.
Table 50. DDDn Bits on Port D Pins(1)
DDDn
PORTDn
PUD
I/O
Pull Up
0
0
x
Input
No
Tri-state (Hi-Z)
0
1
1
Input
No
Tri-state (Hi-Z)
0
1
0
Input
Yes
PDn will source current if ext. pulled low.
1
0
x
Output
No
Push-pull Zero Output
1
1
x
Output
No
Push-pull One Output
Note:
Comment
1. n: 7,6…0, pin number.
Alternate Functions of PORTD • OC2 – PORTD, Bit 7
OC2, Timer/Counter2 Output Compare Match output: The PD7 pin can serve as an
external output for the Timer/Counter2 Output Compare. The pin has to be configured
as an output (DDD7 set (one)) to serve this function. See the Timer description on how
to enable this function. The OC2 pin is also the output pin for the PWM mode timer
function.
• ICP – PORTD, Bit 6
IC P – Inp u t C ap tu re Pin : Th e PD 6 pin ca n a ct a s an In p ut Ca p tu re p in fo r
Timer/Counter1. The pin has to be configured as an input (DDD6 cleared(zero)) to serve
this function. See the timer description on how to enable this function.
• OC1A – PORTD, Bit 5
OC1A, Output Compare Match A output: The PD5 pin can serve as an external output
for the Timer/Counter1 Output Compare A. The pin has to be configured as an output
(DDD5 set (one)) to serve this function. See the timer description on how to enable this
function. The OC1A pin is also the output pin for the PWM mode timer function.
• OC1B – PORTD, Bit 4
OC1B, Output Compare Match B output: The PD4 pin can serve as an external output
for the Timer/Counter1 Output Compare B. The pin has to be configured as an output
(DDD4 set (one)) to serve this function. See the timer description on how to enable this
function. The OC1B pin is also the output pin for the PWM mode timer function.
• INT1 – PORTD, Bit 3
INT1, External Interrupt Source 1: The PD3 pin can serve as an External Interrupt
Source to the MCU. See the interrupt description for further details, and how to enable
the source.
129
1142E–AVR–02/03
• INT0 – PORTD, Bit 2
INT0, External Interrupt Source 0: The PD2 pin can serve as an External Interrupt
Source to the MCU. See the interrupt description for further details, and how to enable
the source.
• TXD – Port D, Bit 1
TXD, Transmit Data (Data output pin for the UART). When the UART Transmitter is
enabled, this pin is configured as an output regardless of the value of DDRD1.
• RXD – Port D, Bit 0
RXD, Receive Data (Data input pin for the UART). When the UART Receiver is enabled
this pin is configured as an input regardless of the value of DDRD0. When the UART
forces this pin to be an input, a logical one in PORTD0 will turn on the internal pull-up.
Port D Schematics
Note that all port pins are synchronized. The synchronization latches are not shown in
the figures.
Figure 74. PORTD Schematic Diagram (Pin PD0)
RD
MOS
PULLUP
PUD
RESET
Q
D
DDD0
C
DATA BUS
WD
RESET
Q
D
PORTD0
C
PD0
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
RXD:
RXEN:
PUD:
130
WRITE PORTD
WRITE DDRD
READ PORTD LATCH
READ PORTD PIN
READ DDRD
UART RECEIVE DATA
UART RECEIVE ENABLE
PULL-UP DISABLE
RXEN
RXD
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Figure 75. PORTD Schematic Diagram (Pin PD1)
RD
MOS
PULLUP
PUD
RESET
Q
R
D
DDD1
C
DATA BUS
WD
RESET
R
Q
D
PORTD1
PD1
C
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
TXD:
TXEN:
PUD:
WRITE PORTD
WRITE DDRD
READ PORTD LATCH
READ PORTD PIN
READ DDRD
UART TRANSMIT DATA
UART TRANSMIT ENABLE
PULL-UP DISABLE
TXEN
TXD
Figure 76. PORTD Schematic Diagram (Pins PD2 and PD3)
PUD
PUD: PULL-UP DISABLE
n:
2, 3
m:
0, 1
131
1142E–AVR–02/03
Figure 77. PORTD Schematic Diagram (Pins PD4 and PD5)
PUD
PUD:
PULL-UP DISABLE
Figure 78. PORTD Schematic Diagram (Pin PD6)
RD
MOS
PULLUP
PUD
RESET
Q
R
D
DDD6
WD
RESET
R
Q
D
PORTD6
PD6
DATA BUS
C
C
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
ACIC:
ACO:
PUD:
132
WRITE PORTD
WRITE DDRD
READ PORTD LATCH
READ PORTD PIN
READ DDRD
COMPARATOR IC ENABLE
COMPARATOR OUTPUT
PULL-UP DISABLE
0
NOISE CANCELER
EDGE SELECT
ICNC1
ICES1
ICF1
1
ACIC
ACO
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Figure 79. PORTD Schematic Diagram (Pin PD7)
PUD
PUD:
PULL-UP DISABLE
133
1142E–AVR–02/03
Memory
Programming
Boot Loader Support
The ATmega163 provides a mechanism for Programming and Re-programming code by
the MCU itself. This feature allows flexible application software updates, controlled by
the MCU using a Flash-resident Boot Loader program. This makes it possible to program the AVR in a target system without access to its SPI pins. The Boot Loader
program can use any available data interface and associated protocol, such as UART
serial bus interface, to input or output program code, and write (program) that code into
the Flash memory, or read the code from the Flash memory.
The ATmega163 Flash memory is organized in two main sections:
•
The Application Flash section
•
The Boot Loader Flash section
The Application Flash section and the Boot Loader Flash section have seperate Boot
Lock bits. Thus the user can select different levels of protection for the two sections. The
Store Program Memory (SPM) instruction can only be executed from the Boot Loader
Flash section.
The Program Flash memory in ATmega163 is divided into 128 pages of 64 words each.
The Boot Loader Flash section is located at the high address space of the Flash, and
can be configured through the BOOTSZ Fuses as shown in Table 51.
Table 51. Boot Size Configuration
BOOTSZ1
134
BOOTSZ0
Boot
Size
Pages
Application Flash
Addresses
Boot Flash
Addresses
1
1
128
Words
2
$0000 - $1F7F
$1F80 - $1FFF
1
0
256
Words
4
$0000 - $1EFF
$1F00 - $1FFF
0
1
512
Words
8
$0000 - $1DFF
$1E00 - $1FFF
0
0
1024
Words
16
$0000 - $1BFF
$1C00 - $1FFF
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Figure 80. Memory Sections
Pages
Program Memory
BOOTSZ = '11'
Pages
Program Memory
BOOTSZ = '10'
$0000
$0000
126
Application Flash Section
(8064 x 16)
2
Boot Flash Section
(128 x 16)
Pages
Program Memory
BOOTSZ = '01'
124
$1F7F
$1F80
4
$1FFF
Pages
Application Flash Section
(7936 x 16)
Boot Flash Section
(256 x 16)
Application Flash Section
(7680 x 16)
$0000
112
16
Boot Flash Section
(512 x 16)
$1FFF
Application Flash Section
(7168 x 16)
$1BFF
$1C00
$1DFF
$1E00
8
$1FFF
Program Memory
BOOTSZ = '00'
$0000
120
$1EFF
$1F00
Boot Flash Section
(1024 x 16)
$1FFF
135
1142E–AVR–02/03
Entering the Boot Loader
Program
The SPM instruction can access the entire Flash, but can only be executed from the
Boot Loader Flash section. If no Boot Loader capability is needed, the entire Flash is
available for application code. Entering the Boot Loader takes place by a jump or call
from the application program. This may be initiated by some trigger such as a command
received via UART or SPI interface, for example. Alternatively, the Boot Reset Fuse can
be programmed so that the Reset Vector is pointing to the Boot Flash start address after
a reset. In this case, the Boot Loader is started after a reset. After the application code is
loaded, the program can start executing the application code. Note that the fuses cannot
be changed by the MCU itself. This means that once the Boot Reset Fuse is programmed, the Reset Vector will always point to the Boot Loader Reset and the fuse can
only be changed through the serial or parallel programming interface.
Table 52. Boot Reset Fuse
BOOTRST
Reset Address
1
Reset Vector = Application Reset (address $0000)
0
Reset Vector = Boot Loader Reset (see Table 51)
Capabilities of the Boot
Loader
The program code within the Boot Loader section has the capability to read from and
write into the entire Flash, including the Boot Loader memory. This allows the user to
update both the Application code and the Boot Loader code that handles the software
update. The Boot Loader can thus even modify itself, and it can also erase itself from
the code if the feature is not needed anymore.
Self-Programming the
Flash
Programming of the Flash is executed one page at a time. The Flash page must be
erased first for correct programming. The general Write Lock (Lock bit 2) does not control the programming of the Flash memory by SPM instruction. Similarly, the general
Read/Write Lock (Lock bit 1) does not control reading nor writing by LPM/SPM, if it is
attempted.
The Program memory can only be updated page by page, not word by word. One page
is 128 bytes (64 words). The Program memory will be modified by first performing Page
Erase, then filling the temporary page buffer one word at a time using SPM, and
then executing Page Write. If only part of the page needs to be changed, the other
parts must be stored (for example in internal SRAM) before the erase, and then be rewritten. The temporary page buffer can be accessed in a random sequence. It is essential that the page address used in both the Page Erase and Page Write operation is
addressing the same page. See “Assembly code example for a Boot Loader” on page
141 for an assembly code example.
Se e Table 60 on p age 156 for typical p rogr amming times w hen usin g SelfProgramming.
Performing Page Erase by
SPM
To execute Page Erase, set up the address in the Z-pointer, write “00011” to the five
LSB in SPMCR and execute SPM within four clock cycles after writing SPMCR. The
data in R1 and R0 is ignored. The page address must be written to Z13:Z7. Other bits in
the Z-pointer will be ignored during this operation. It is recommended that the interrupts
are disabled during the page erase operation.
Fill the Temporary Buffer
(Page Load)
To write an instruction word, set up the address in the Z-pointer and data in R1:R0, write
“00001” to the five LSB in SPMCR and execute SPM within four clock cycles after writing SPMCR. The content of Z6:Z1 is used to address the data in the temporary buffer.
Z13:Z7 must point to the page that is supposed to be written.
136
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Perform a Page Write
To execute Page Write, set up the address in the Z-pointer, write “00101” to the five LSB
in SPMCR and execute SPM within four clock cycles after writing SPMCR. The data in
R1 and R0 is ignored. The page address must be written to Z13:Z7. During this operation, Z6:Z0 must be zero to ensure that the page is written correctly. It is recommended
that the interrupts are disabled during the page write operation.
Consideration while Updating
the Boot Loader Section
Special care must be taken if the user allows the Boot Loader section to be updated by
leaving Boot Lock bit 11 unprogrammed. An accidental write to the Boot Loader itself
can corrupt the entire Boot Loader, and further software updates might be impossible. If
it is not necessary to change the Boot Loader software itself, it is recommended to program the Boot Lock Bit 11 to protect the Boot Loader software from any internal
software changes.
Wait for SPM Instruction to
Complete
Though the CPU is halted during Page Write, Page Erase or Lock bit write, for future
compatibility, the user software must poll for SPM complete by reading the SPMCR
Register and loop until the SPMEN bit is cleared after a programming operation. See
“Assembly code example for a Boot Loader” on page 141 for a code example.
Instruction Word Read after
Page Erase, Page Write, and
Lock Bit Write
To ensure proper instruction pipelining after programming action (Page Erase, Page
Write, or Lock bit write), the SPM instruction must be followed with the sequence (.dw
$FFFF - NOP) as shown below:
spm
.dw $FFFF
nop
If not, the instruction following SPM might fail. It is not necessary to add this sequence
when the SPM instruction only loads the temporary buffer.
Avoid Reading the Application
Section During SelfProgramming
During Self-Programming (either Page Erase or Page Write), the user software should
not read the application section. The user software itself must prevent addressing this
section during the Self-Programming operations. This implies that interrupts must be
disabled. Before addressing the application section after the programming is completed,
for future compatibility, the user software must write “10001” to the five LSB in SPMCR
and execute SPM within four clock cycles. Then the user software should verify that the
ASB bit is cleared. See “Assembly code example for a Boot Loader” on page 141 for an
example. Though the ASB and ASRE bits have no special function in this device, it is
important for future code compatibility that they are treated as described above.
Boot Loader Lock Bits
ATmega163 has two separate sets of Boot Lock bits which can be set independently.
This gives the user a unique flexibility to select different levels of protection.
The user can select:
•
To protect the entire Flash from a software update by the MCU
•
To only protect the Boot Loader Flash section from a software update by the MCU
•
To only protect application Flash section from a software update by the MCU
•
Allowing software update in the entire Flash
See Table and Table for further details. The Boot Lock bits can be set in software and
in Serial or Parallel Programming mode, but they can only be cleared by a chip erase
command.
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1142E–AVR–02/03
Table 53. Boot Lock Bit0 Protection Modes (Application Section) (1)
BLB0 mode
BLB02
BLB01
1
1
1
No restrictions for SPM, LPM accessing the Application
section
2
1
0
SPM is not allowed to write to the Application section
3
0
0
SPM is not allowed to write to the Application section, and
LPM executing from the Boot Loader section is not
allowed to read from the Application section
4
0
1
LPM executing from the Boot Loader section is not
allowed to read from the Application section
Note:
Protection
1. “1” means unprogrammed, “0” means programmed
Table 54. Boot Lock Bit1 Protection Modes (Boot Loader Section)(1)
BLB1 mode
BLB12
BLB11
1
1
1
No restrictions for SPM, LPM accessing the Boot Loader
section
2
1
0
SPM is not allowed to write to the Boot Loader section
0
SPM is not allowed to write to the Boot Loader section,
and LPM executing from the Application section is not
allowed to read from the Boot Loader section. If code is
executed from Boot section, the interrupts are disabled
when BLB12 is programmed.
1
LPM executing from the Application section is not allowed
to read from the Boot Loader section. If code is executed
from Boot section, the interrupts are disabled when BLB12
is programmed.
3
0
4
Note:
Setting the Boot Loader Lock
Bits by SPM
0
Protection
1. “1” means unprogrammed, “0” means programmed
To set the Boot Loader Lock bits, write the desired data to R0, write “00001001” to
SPMCR and execute SPM within four clock cycles after writing SPMCR. The only
accessible Lock bits are the Boot Lock bits that may prevent the Application and Boot
Loader section from any software update by the MCU.
Bit
7
6
5
4
3
2
1
0
R0
1
1
BLB12
BLB11
BLB02
BLB01
1
1
If bits 5..2 in R0 are cleared (zero), the corresponding Boot Lock bit will be programmed
if an SPM instruction is executed within four cycles after BLBSET and SPMEN are set in
SPMCR.
Reading the Fuse and Lock
Bits from Software
138
It is possible to read both the Fuse and Lock bits from software. To read the Lock bits,
load the Z-pointer with $0001 and set the BLBSET and SPMEN bits in SPMCR. When
an LPM instruction is executed within five CPU cycles after the BLBSET and SPMEN
bits are set in SPMCR, the value of the Lock bits will be loaded in the destination register. The BLBSET and SPMEN bits will auto-clear upon completion of reading the Lock
bits or if no SPM, or LPM, instruction is executed within four, respectively five, CPU
cycles. When BLBSET and SPMEN are cleared, LPM will work as described in “Constant Addressing Using The LPM and SPM Instructions” on page 15 and in the
Instruction set Manual.
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Bit
7
6
5
4
3
2
1
0
Rd
–
–
BLB12
BLB11
BLB02
BLB01
LB2
LB1
The algorithm for reading the Fuse Low bits is similar to the one described above for
reading the Lock bits. To read the Fuse Low bits, load the Z-pointer with $0000 and set
the BLBSET and SPMEN bits in SPMCR. When an LPM instruction is executed within
five cycles after the BLBSET and SPMEN bits are set in the SPMCR, the value of the
Fuse Low bits will be loaded in the destination register as shown below.
Bit
7
6
5
4
3
2
1
0
Rd
BODLEVEL
BODEN
SPIEN
–
CKSEL3
CKSEL2
CKSEL1
CKSEL0
Similarly, when reading the Fuse High bits, load $0003 in the Z-pointer. When an LPM
instruction is executed within five cycles after the BLBSET and SPMEN bits are set in
the SPMCR, the value of the Fuse High bits will be loaded in the destination register as
shown below.
Bit
7
6
5
4
3
2
1
0
Rd
–
–
–
–
–
BOOTSZ1
BOOTSZ0
BOOTRST
Fuse and Lock bits that are programmed, will be read as zero. Fuse and Lock bits that
are unprogrammed, will be read as one.
In all cases, the read value of unused bit positions are undefined.
EEPROM Write Prevents
Writing to SPMCR
Note that an EEPROM write operation will block all software programming to Flash.
Reading the Fuses and Lock bits from software will also be prevented during the
EEPROM write operation. It is recommended that the user checks the status bit (EEWE)
in the EECR Register and verifies that the bit is cleared before writing to the SPMCR
Register. If EEPROM writing is performed inside an interrupt routine, the user software
should disable that interrupt before checking the EEWE status bit.
Addressing the Flash During
Self-Programming
The Z-pointer is used to address the SPM commands.
Bit
15
14
13
12
11
10
9
8
ZH (R31)
Z15
Z14
Z13
Z12
Z11
Z10
Z9
Z8
ZL (R30)
Z7
Z6
Z5
Z4
Z3
Z2
Z1
Z0
7
6
5
4
3
2
1
0
Z15:Z14 always ignored
Z13:Z7
page select, for page erase and page write
Z6:Z1
word select, for filling temp buffer (must be zero during page write operation)
Z0
should be zero for all SPM commands, byte select for the LPM instruction.
The only operation that does not use the Z-pointer is Setting the Boot Loader Lock bits.
The content of the Z-pointer is ignored and will have no effect on the operation.
Note that the Page Erase and Page Write operation is addressed independently. Therefore it is of major importance that the Boot Loader software addresses the same page in
both the page erase and page write operation.
The LPM instruction also uses the Z-pointer to store the address. Since this instruction
addresses the Flash byte-by-byte, also the LSB (bit Z0) of the Z-pointer is used. See
page 15 for a detailed description.
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Store Program Memory
Control Register – SPMCR
The Store Program Memory Control Register contains the control bits needed to control
the programming of the Flash from internal code execution.
Bit
7
6
5
4
3
2
1
0
$37 ($57)
–
ASB
–
ASRE
BLBSET
PGWRT
PGERS
SPMEN
Read/Write
R
R
R
R/W
R/W
R/W
R/W
R/W
Initial Value
x
0
0
0
0
0
0
0
SPMCR
• Bit 7 – Res: Reserved Bit
This bit is a reserved bit in the ATmega163 and always reads as zero. This bit should be
written to zero when writing SPMCR.
• Bit 6 – ASB: Application Section Busy
Before entering the Application section after a Boot Loader operation (Page Erase or
Page Write) the user software must verify that this bit is cleared. In future devices, this
bit will be set to “1” by Page Erase and Page Write. In ATmega163, this bit always reads
as zero.
• Bit 5 – Res: Reserved Bit
This bit is a reserved bit in the ATmega163 and always reads as zero. This bit should be
written to zero when writing SPMCR.
• Bit 4 – ASRE: Application Section Read Enable
Before re-entering the Application section, the user software must set this bit together
with the SPMEN bit and execute SPM within four clock cycles.
• Bit 3 – BLBSET: Boot Lock Bit Set
If this bit is set at the same time as SPMEN, the next SPM instruction within four clock
cycles will set Boot Lock bits. Alternatively, an LPM instruction within five cycles will
read either the Lock bBits or the Fuse bits. The BLBSET bit will auto-clear upon completion of the SPM or LPM instruction, or if no SPM, or LPM, instruction is executed within
four, respectively five, clock cycles.
• Bit 2 – PGWRT: Page Write
If this bit is set at the same time as SPMEN, the next SPM instruction within four clock
cycles executes Page Write, with the data stored in the temporary buffer. The page
address is taken from the high part of the Z-pointer. The data in R1 and R0 are ignored.
The PGWRT bit will auto-clear upon completion of a page write, or if no SPM instruction
is executed within four clock cycles. The CPU is halted during the entire Page Write
operation.
• Bit 1 – PGERS: Page Erase
If this bit is set at the same time as SPMEN, the next SPM instruction within four clock
cycles executes Page Erase. The page address is taken from the high part of the Zpointer. The data in R1 and R0 are ignored. The PGERS bit will auto-clear upon completion of a Page Erase, or if no SPM instruction is executed within four clock cycles. The
CPU is halted during the entire Page Erase operation.
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ATmega163(L)
• Bit 0 – SPMEN: Store Program Memory Enable
This bit enables the SPM instruction for the next four clock cycles. If set together with
either ASRE, BLBSET, PGWRT, or PGERS, the following SPM instruction will have a
special meaning, see description above. If only SPMEN is set, the following SPM
instruction will store the value in R1:R0 in the temporary page buffer addressed by the
Z-pointer. The LSB of the Z-pointer is ignored. The SPMEN bit will auto-clear upon completion of an SPM instruction, or if no SPM instruction is executed within four clock
cycles. During Page Erase and Page Write, the SPMEN bit remains high until the operation is completed.
Writing any other combination than “10001”, “01001”, “00101”, or “00001” in the lower
five bits will have no effect.
Preventing Flash
Corruption
During periods of low VCC, the Flash can be corrupted because the supply voltage is too
low for the CPU and the Flash to operate properly. These issues are the same as for
board level systems using the Flash, and the same design solutions should be applied.
A Flash corruption can be caused by two situations when the voltage is too low. First, a
regular write sequence to the Flash requires a minimum voltage to operate correctly.
Secondly, the CPU itself can execute instructions incorrectly, if the supply voltage for
executing instructions is too low.
Flash corruption can easily be avoided by following these design recommendations (one
is sufficient):
1. Keep the AVR RESET active (low) during periods of insufficient power supply
voltage. This can be done be enabling the internal Brown-out Detector (BOD) if
the operating voltage matches the detection level. If not, an external low VCC
Reset Protection circuit can be used. If a Reset occurs while a write operation is
in progress, the write operation will be completed provided that the power supply
voltage is sufficient. The total Reset Time must be longer thatn the Flash write
time. This can be achieved by holding the External Reset, or by selecting a long
Reset Time-out.
2. Keep the AVR core in Power-down sleep mode during periods of low VCC. This
will prevent the CPU from attempting to decode and execute instructions, effectively protecting the Flash from unintentional writes.
Assembly code example for a
Boot Loader
;- the routine writes one page of data from RAM to Flash
; the first data location in RAM is pointed to by the Y pointer (lowest
address)
; the first data location in Flash is pointed to by the Z-pointer (lowest
address)
;- error handling is not included
;- the routine must be placed inside the boot space
; Only code inside boot loader
; section should be read during Self-Programming.
;- registers used: r0, r1, temp1, temp2, looplo, loophi, spmcrval
; storing and restoring of registers is not included in the routine
; register usage can be optimized at the expense of code size
;- It is assumed that the interrupts are disabled
.equ
PAGESIZEB = PAGESIZE*2
;PAGESIZEB is page size in BYTES,
not words
.org SMALLBOOTSTART
Write_page:
; page erase
ldi
spmcrval, (1<<PGERS) + (1<<SPMEN)
call
Do_spm
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; re-enable the Application Section
ldi
spmcrval, (1<<ASRE) + (1<<SPMEN)
call
Do_spm
; transfer
ldi
ldi
Wrloop:
ld
ld
ldi
call
adiw
sbiw
brne
data from RAM to Flash page buffer
looplo, low(PAGESIZEB)
;init loop variable
loophi, high(PAGESIZEB)
;not required for PAGESIZEB<=256
r0, Y+
r1, Y+
spmcrval, (1<<SPMEN)
Do_spm
ZH:ZL, 2
loophi:looplo, 2
Wrloop
;use subi for PAGESIZEB<=256
; execute page write
subi
ZL, low(PAGESIZEB)
;restore pointer
sbci
ZH, high(PAGESIZEB)
;not required for PAGESIZEB<=256
ldi
spmcrval, (1<<PGWRT) + (1<<SPMEN)
call
Do_spm
; re-enable the Application Section
ldi
spmcrval, (1<<ASRE) + (1<<SPMEN)
call
Do_spm
; read back and check, optional
ldi
looplo, low(PAGESIZEB)
;init loop variable
ldi
loophi, high(PAGESIZEB)
;not required for PAGESIZEB<=256
subi
YL, low(PAGESIZEB)
;restore pointer
sbci
YH, high(PAGESIZEB)
Rdloop:
lpm
r0, Z+
ld
r1, Y+
cpse
r0, r1
jmp
Error
sbiw
loophi:looplo, 1
;use subi for PAGESIZEB<=256
brne
Rdloop
; return to Application Section
; verify that Application Section is safe to read
Return:
in
temp1, SPMCR
sbrs
temp1, ASB
; If ASB is set, the AS is not ready yet
ret
; re-enable the Applicaiton Section
ldi
spmcrval, (1<<ASRE) + (1<<SPMEN)
call
Do_spm
rjmp
Return
Do_spm:
; input: spmcrval determines SPM action
; check that no EEPROM write access is running
Wait_ee:
sbic
EECR, EEWE
rjmp
Wait_ee
; SPM timed sequence
out
SPMCR, spmcrval
spm
.dw $FFFF
nop
; check for SPM complete
Wait_spm:
in
temp1, SPMCR
142
; ensure proper pipelining
; of next instruction
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
sbrc
rjmp
ret
Program and Data
Memory Lock Bits
temp1, SPMEN
Wait_spm
The ATmega163 provides six Lock bits which can be left unprogrammed (“1”) or can be
programmed (“0”) to obtain the additional features listed in Table 55. The Lock bits can
only be erased to “1” with the Chip Erase command.
Table 55. Lock Bit Protection Modes
Memory Lock Bits
LB mode
LB1
LB2
1
1
1
No memory lock features enabled for Parallel and Serial
Programming.
1
Further programming of the Flash and EEPROM is
disabled in Parallel and Serial Programming mode. The
Fuse bits are locked in both Serial and Parallel
Programming mode.(1)
Further programming and verification of the Flash and
EEPROM is disabled in Parallel and Serial Programming
mode. The Fuse bits are locked in both Serial and Parallel
Programming mode.(1)
2
0
Protection Type
3
0
0
BLB0 mode
BLB01
BLB02
1
1
1
No restrictions for SPM, LPM accessing the Application
section.
2
0
1
SPM is not allowed to write to the Application section.
3
0
0
SPM is not allowed to write to the Application section, and
LPM executing from the Boot Loader section is not
allowed to read from the Application section.
4
1
0
LPM executing from the Boot Loader section is not
allowed to read from the Application section.
BLB1 mode
BLB11
BLB12
1
1
1
No restrictions for SPM, LPM accessing the Boot Loader
section.
2
0
1
SPM is not allowed to write to the Boot Loader section.
0
SPM is not allowed to write to the Boot Loader section,
and LPM executing from the Application section is not
allowed to read from the Boot Loader section. If code
executed from the Boot Section, the interrupts are
disabled when BLB12 is programmed.
0
LPM executing from the Application section is not allowed
to read from the Boot Loader section. If code executed
from the Boot Section, the interrupts are disabled when
BLB12 is programmed.
3
4
Note:
0
1
1. Program the Fuse bits before programming the Lock bits.
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Fuse Bits
The ATmega163 has ten Fuse bits, divided in two groups. The Fuse High bits are
BOOTSZ1..0 and BOOTRST, and the Fuse Low bits are BODLEVEL, BODEN, SPIEN,
and CKSEL3..0.
•
BOOTSZ1..0 select the size and start address of the Boot Flash section according
to Table 51 on page 134. Default value is “11” (both unprogrammed).
•
When BOOTRST is programmed (“0”), the Reset Vector is set to the start address of
the Boot Flash section, as selected by the BOOTSZ fuses according to Table 51 on
page 134. If the BOOTRST is unprogrammed (“1”), the Reset Vector is set to
address $0000. Default value is unprogrammed (“1”).
•
The BODLEVEL Fuse selects the Brown-out Detection Level and changes the Startup times, according to Table 4 on page 24 and Table 5 on page 25, respectively.
Default value is unprogrammed (“1”).
•
When the BODEN Fuse is programmed (“0”), the Brown-out Detector is enabled.
See “Reset and Interrupt Handling” on page 21. Default value is unprogrammed
(“1”).
•
When the SPIEN Fuse is programmed (“0”), Serial Program and Data Downloading
are enabled. Default value is programmed (“0”). The SPIEN Fuse is not accessible
in serial programming mode.
•
CKSEL3..0 select the clock source and the start-up delay after reset, according to
Table 1 on page 5 and Table 5 on page 25. Default value is “0010” (Internal RC
Oscillator).
The status of the Fuse bits is not affected by Chip Erase. Note that the Fuse bits are
locked if Lock bit1 (LB1) is programmed. Program the Fuse bits before programming the
Lock bits.
Signature Bytes
All Atmel microcontrollers have a three-byte signature code which identifies the device.
This code can be read in both serial and parallel mode. The three bytes reside in a separate address space.
The ATmega163 the signature bytes are:
1. $000: $1E (indicates manufactured by Atmel).
2. $001: $94 (indicates 16KB Flash memory).
3. $002: $02 (indicates ATmega163 device when $001 is $94).
Calibration Byte
144
The ATmega163 has a one byte calibration value for the internal RC Oscillator. This
byte resides in the high byte of address $000 in the signature address space. During
Memory Programming, the external programmer must read this location and program it
into a selected location in the normal Flash Program memory. At start-up, the user software must read this Flash location and write the value to the OSCCAL Register.
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Parallel Programming
This section describes how to Parallel Program and verify Flash Program memory,
EEPROM Data memory + Program And Data Memory Lock bits and Fuse bits in the
ATmega163. Pulses are assumed to be at least 500ns unless otherwise noted.
Signal Names
In this section, some pins of the ATmega163 are referenced by signal names describing
their functionality during parallel programming, see Figure 81 and Table 56. Pins not
described in the following table are referenced by pin names.
The XA1/XA0 pins determine the action executed when the XTAL1 pin is given a positive pulse. The bit coding are shown in Table 57.
When pulsing WR or OE, the command loaded determines the action executed. The
Command is a byte where the different bits are assigned functions as shown in Table
58.
The BS2 pin should be low unless otherwise noted.
Figure 81. Parallel Programming
ATmega163
+5V
RDY/BSY
PD1
OE
PD2
WR
PD3
BS1
PD4
XA0
PD5
XA1
PD6
PAGEL
PD7
VCC
+5V
AVCC
PB7 - PB0
+12 V
BS2
DATA
RESET
PA0
XTAL1
AGND
GND
Table 56. Pin Name Mapping
Signal Name in
Programming Mode
Pin Name
I/O
Function
RDY/BSY
PD1
O
0: Device is busy programming, 1: Device is ready
for new command
OE
PD2
I
Output Enable (Active low)
WR
PD3
I
Write Pulse (Active low)
BS1
PD4
I
Byte Select 1 (“0” selects low byte, “1” selects high
byte)
XA0
PD5
I
XTAL Action Bit 0
XA1
PD6
I
XTAL Action Bit 1
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1142E–AVR–02/03
Table 56. Pin Name Mapping (Continued)
Signal Name in
Programming Mode
Pin Name
I/O
PAGEL
PD7
I
Program Memory Page Load
BS2
PA0
I
Byte Select 2 (“0” selects low byte, “1” selects 2’nd
high byte)
DATA
PB7 - 0
I/O
Function
Bidirectional Databus (Output when OE is low)
Table 57. XA1 and XA0 Coding
XA1
XA0
Action when XTAL1 is Pulsed
0
0
Load Flash or EEPROM Address (High or low address byte determined by
BS1)
0
1
Load Data (High or Low data byte for Flash determined by BS1)
1
0
Load Command
1
1
No Action, Idle
Table 58. Command Byte Bit Coding
Command Byte
Enter Programming Mode
Command Executed
1000 0000
Chip Erase
0100 0000
Write Fuse Bits
0010 0000
Write Lock Bits
0001 0000
Write Flash
0001 0001
Write EEPROM
0000 1000
Read Signature Bytes
0000 0100
Read Fuse and Lock Bits
0000 0010
Read Flash
0000 0011
Read EEPROM
The following algorithm puts the device in Parallel Programming mode:
1. Apply 4.5 - 5.5V between VCC and GND.
2. Set RESET and BS pins to “0” and wait at least 100 ns.
3. Apply 11.5 - 12.5V to RESET. Any activity on BS1 within 100 ns after +12V has
been applied to RESET, will cause the device to fail entering Programming
mode.
Chip Erase
The Chip Erase command will erase the Flash and EEPROM memories and the Lock
bits. The Lock bits are not reset until the Program memory has been completely erased.
The Fuse bits are not changed. A Chip Erase must be performed before the Flash is reprogrammed.
Load Command “Chip Erase”
1. Set XA1, XA0 to “10”. This enables command loading.
2. Set BS1 to “0”.
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ATmega163(L)
3. Set DATA to “1000 0000”. This is the command for Chip Erase.
4. Give WR a negative pulse. This starts the Chip Erase. RDY/BSY goes low.
5. Wait until RDY/BSY goes high before loading a new command.
Programming the Flash
The Flash is organized as 128 pages of 128 bytes each. When programming the Flash,
the program data is latched into a page buffer. This allows one page of program data to
be programmed simultaneously. The following procedure describes how to program the
entire Flash memory:
A. Load Command “Write Flash”
1. Set XA1, XA0 to “10”. This enables command loading.
2. Set BS1 to “0”.
3. Set DATA to “0001 0000”. This is the command for Write Flash.
4. Give XTAL1 a positive pulse. This loads the command.
B. Load Address Low Byte
1. Set XA1, XA0 to “00”. This enables address loading.
2. Set BS1 to “0”. This selects low address.
3. Set DATA = Address Low Byte ($00 - $FF).
4. Give XTAL1 a positive pulse. This loads the address Low Byte.
C. Load Data Low Byte
1. Set XA1, XA0 to “01”. This enables data loading.
2. Set DATA = Data Low Byte ($00 - $FF).
3. Give XTAL1 a positive pulse. This loads the data byte.
D. Latch Data Low Byte
1. Set BS1 to “0”. This selects Low Data Byte.
2. Give PAGEL a positive pulse. This latches the data Low Byte.
(See Figure 82 for signal waveforms)
E. Load Data High Byte
1. Set BS1 to “1”. This selects High Data Byte.
2. Set XA1, XA0 to “01”. This enables data loading.
3. Set DATA = Data High Byte ($00 - $FF).
4. Give XTAL1 a positive pulse. This loads the data byte.
F. Latch Data High Byte
1. Set BS1 to “1”. This selects High Data Byte.
2. Give PAGEL a positive pulse. This latches the data High Byte.
G. Repeat B through F 64 times to fill the page buffer.
To address a page in the Flash, seven bits are needed (128 pages). The five most significant bits are read from address high byte as described in section “H” below. The two
least significant page address bits however, are the two most significant bits (bit7 and
bit6) of the latest loaded address low byte as described in section “B”.
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H. Load Address High byte
1. 1. Set XA1, XA0 to “00”. This enables address loading.
2. Set BS1 to “1”. This selects high address.
3. Set DATA = Address High Byte ($00 - $1F).
4. Give XTAL1 a positive pulse. This loads the address High Byte.
I. Program Page
1. Give WR a negative pulse. This starts programming of the entire page of
data. RDY/BSYgoes low.
2. Wait until RDY/BSY goes high.
(See Figure 83 for signal waveforms)
J. End Page Programming
1. Set XA1, XA0 to “10”. This enables command loading.
2. Set DATA to “0000 0000”. This is the command for No Operation.
3. Give XTAL1 a positive pulse. This loads the command, and the internal write
signals are reset.
K. Repeat A through J 128 times or until all data has been programmed.
Figure 82. Programming the Flash Waveforms
DATA
$10
ADDR. LOW
ADDR. HIGH
DATA LOW
XA1
XA2
BS1
XTAL1
WR
DY/BSY
RESET +12V
OE
BS2
PAGEL
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ATmega163(L)
Figure 83. Programming the Flash Waveforms (continued)
DATA
DATA HIGH
XA1
XA0
BS1
XTAL1
WR
RDY/BSY
RESET
+12V
OE
PAGEL
BS2
Programming the EEPROM
The programming algorithm for the EEPROM Data Memory is as follows (refer to “Programming the Flash” on page 147 for details on Command, Address and Data loading):
1. A: Load Command “0001 0001”.
2. H: Load Address High Byte ($00 - $01)
3. B: Load Address Low Byte ($00 - $FF)
4. E: Load Data Low Byte ($00 - $FF)
L: Write Data Low Byte
1. Set BS to “0”. This selects low data.
2. Give WR a negative pulse. This starts programming of the data byte.
RDY/BSY goes low.
3. Wait until to RDY/BSY goes high before programming the next byte.
(See Figure 84 for signal waveforms)
The loaded command and address are retained in the device during programming. For
efficient programming, the following should be considered.
•
The command needs only be loaded once when writing or reading multiple memory
locations.
•
Address high byte needs only be loaded before programming a new 256 word page
in the EEPROM.
•
Skip writing the data value $FF, that is the contents of the entire EEPROM after a
Chip Erase.
These considerations also applies to Flash, EEPROM and Signature bytes reading.
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Figure 84. Programming the EEPROM Waveforms
DATA
$11
ADDR. HIGH
ADDR. LOW
DATA LOW
XA1
XA2
BS1
XTAL1
WR
RDY/BSY
RESET +12V
OE
BS2
PAGEL
Reading the Flash
The algorithm for reading the Flash memory is as follows (refer to “Programming the
Flash” on page 147 for details on Command and Address loading):
1. A: Load Command “0000 0010”.
2. H: Load Address High Byte ($00 - $1F).
3. B: Load Address Low Byte ($00 - $FF).
4. Set OE to “0”, and BS1 to “0”. The Flash word low byte can now be read at DATA.
5. Set BS to “1”. The Flash word high byte can now be read at DATA.
6. Set OE to “1”.
Reading the EEPROM
The algorithm for reading the EEPROM memory is as follows (refer to “Programming the
Flash” on page 147 for details on Command and Address loading):
1. A: Load Command “0000 0011”.
2. H: Load Address High Byte ($00 - $01).
3. B: Load Address ($00 - $FF).
4. Set OE to “0”, and BS1 to “0”. The EEPROM Data byte can now be read at
DATA.
5. Set OE to “1”.
Programming the Fuse Low
Bits
The algorithm for programming the Fuse Low bits is as follows (refer to “Programming
the Flash” on page 147 for details on Command and Data loading):
1. A: Load Command “0100 0000”.
2. C: Load Data Low Byte. Bit n = “0” programs and bit n = “1” erases the Fuse bit.
Bit 7 = BODLEVEL Fuse bit
Bit 6 = BODEN Fuse bit
Bit 5 = SPIEN Fuse bit
Bit 3..0 = CKSEL3..0 Fuse bits
Bit 4 = “1”. This bit is reserved and should be left unprogrammed (“1”).
3. Give WR a negative pulse and wait for RDY/BSY to go high.
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ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Programming the Fuse High
Bits
The algorithm for programming the Fuse high bits is as follows (refer to “Programming
the Flash” on page 147 for details on Command and Data loading):
1. A: Load Command “0100 0000”.
2. C: Load Data Low Byte. Bit n = “0” programs and bit n = “1” erases the Fuse bit.
Bit 2..1 = BOOTSZ1..0 Fuse bits
Bit 0 = BOOTRST Fuse bit
Bit 7..3 = “1”. These bits are reserved and should be left unprogrammed (“1”).
3. Set BS1 to “1”. This selects high data byte.
4. Give WR a negative pulse and wait for RDY/BSY to go high.
5. Set BS1 to “0”. This selects low data byte.
Programming the Lock Bits
The algorithm for programming the Lock bits is as follows (refer to “Programming the
Flash” on page 147 for details on Command and Data loading):
1. A: Load Command “0010 0000”.
2. D: Load Data Low Byte. Bit n = “0” programs the Lock bit.
Bit 5 = Boot Lock bit12
Bit 4 = Boot Lock bit11
Bit 3 = Boot Lock bit02
Bit 2 = Boot Lock bit01
Bit 1 = Lock bit2
Bit 0 = Lock bit1
Bit 7..6 = “1”. These bits are reserved and should be left unprogrammed (“1”).
3. L: Write Data Low Byte.
The Lock bits can only be cleared by executing Chip Erase.
Reading the Fuse and Lock
Bits
The algorithm for reading the Fuse and Lock bits is as follows (refer to “Programming
the Flash” on page 147 for details on Command loading):
1. A: Load Command “0000 0100”.
2. Set OE to “0”, BS2 to “0” and BS1 to “0”. The status of the Fuse Low bits can
now be read at DATA (“0” means programmed).
Bit 7 = BODLEVEL Fuse bit
Bit 6 = BODEN Fuse bit
Bit 5 = SPIEN Fuse bit
Bit 3..0 = CKSEL3..0 Fuse bits
3. Set OE to “0”, BS2 to “1” and BS1 to “1”. The status of the Fuse High bits can
now be read at DATA (“0” means programmed).
Bit 2..1 = BOOTSZ1..0 Fuse bits
Bit 0 = BOOTRST Fuse bit
4. Set OE to “0”, BS2 to “0” and BS1 to “1”. The status of the Lock bits can now be
read at DATA (“0” means programmed).
Bit 5 = Boot Lock bit12
Bit 4 = Boot Lock bit11
Bit 3 = Boot Lock bit02
Bit 2 = Boot Lock bit01
Bit 1 = Lock bit2
Bit 0 = Lock bit1
5. Set OE to “1”.
151
1142E–AVR–02/03
Reading the Signature Bytes
The algorithm for reading the Signature bytes is as follows (refer to Programming the
Flash for details on Command and Address loading):
1. A: Load Command “0000 1000”.
2. C: Load Address Low Byte ($00 - $02).
3. Set OE to “0”, and BS to “0”. The selected Signature byte can now be read at
DATA.
4. Set OE to “1”.
Reading the Calibration Byte
The algorithm for reading the Calibration byte is as follows (refer to Programming the
Flash for details on Command and Address loading):
1. A: Load Command “0000 1000”.
2. C: Load Address Low Byte, $00.
Set OE to “0”, and BS1 to “1”. The Calibaration byte can now be read at DATA.
3. Set OE to “1”.
152
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Parallel Programming
Characteristics
Figure 85. Parallel Programming Timing
tXLWL
tXHXL
XTAL1
tDVXH
tXLDX
Data & Contol
(DATA, XA0/1, BS1, BS2)
tPLBX t BVWL
tBVPH
PAGEL
tRHBX
tPHPL
Write
tWLWH
WR
tPLWL
WLRL
RDY/BSY
tWLRH
tXLOL
tOHDZ
tOLDV
Read
OE
DATA
Table 59. Parallel Programming Characteristics, TA = 25°C ± 10%, VCC = 5 V ± 10%
Symbol
Parameter
Min
VPP
Programming Enable Voltage
11.5
IPP
Programming Enable Current
tDVXH
Data and Control Valid before XTAL1 High
67
ns
tXHXL
XTAL1 Pulse Width High
67
ns
tXLDX
Data and Control Hold after XTAL1 Low
67
ns
tXLWL
XTAL1 Low to WR Low
67
ns
tBVPH
BS1 Valid before PAGEL High
67
ns
tPHPL
PAGEL Pulse Width High
67
ns
tPLBX
BS1 Hold after PAGEL Low
67
ns
tPLWL
PAGEL Low to WR Low
67
ns
tBVWL
BS1 Valid to WR Low
67
ns
tRHBX
BS1 Hold after RDY/BSY High
67
ns
tWLWH
WR Pulse Width Low
67
ns
tWLRL
WR Low to RDY/BSY Low
0
(1)
tWLRH
WR Low to RDY/BSY High
tWLRH_CE
WR Low to RDY/BSY High for Chip Erase(2)
tWLRH_FLASH
WR Low to RDY/BSY High for Write Flash
tXLOL
XTAL1 Low to OE Low
tOLDV
OE Low to DATA Valid
tOHDZ
OE High to DATA Tri-stated
Notes:
Typ
(3)
Max
Units
12.5
V
250
µA
2.5
µs
1
1.5
1.9
ms
16
23
30
ms
8
12
15
ms
67
ns
20
ns
20
ns
1.
tWLRH is valid for the Write EEPROM, Write Fuse Bits and Write Lock Bits
commands.
2. tWLRH_CE is valid for the Chip Erase command.
3. tWLRH_FLASH is valid for the Write Flash command.
153
1142E–AVR–02/03
Serial Downloading
Both the Flash and EEPROM memory arrays can be programmed using the serial SPI
bus while RESET is pulled to GND. The serial interface consists of pins SCK, MOSI
(input) and MISO (output). After RESET is set low, the Programming Enable instruction
needs to be executed first before program/erase operations can be executed.
Figure 86. Serial Programming and Verify(1)
ATmega163
2.7 - 5.5V
VCC
2.7 - 5.5V
MOSI
PB5
MISO
PB6
SCK
PB7
(2)
AVCC
XTAL1
RESET
GND
Notes:
AGND
1. If the device is clocked by the internal Oscillator, connecting a clock source to XTAL1
is not required.
2. VCC - 0.3 V < AVCC < VCC + 0.3 V, however, AVCC should always be within 2.7 5.5 V.
When programming the EEPROM, an auto-erase cycle is built into the self-timed programming operation (in the Serial mode ONLY) and there is no need to first execute the
Chip Erase instruction. The Chip Erase operation turns the content of every memory
location in both the Program and EEPROM arrays into $FF.
The Program and EEPROM memory arrays have separate address spaces:
$0000 to $1FFF for Program memory and $0000 to $01FF for EEPROM memory.
The device can be clocked by any clock option during Serial Programming. The minimum low and high periods for the serial clock (SCK) input are defined as follows:
Low: > 2 MCU clock cycles
High: > 2 MCU clock cycles
154
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Serial Programming
Algorithm
When writing serial data to the ATmega163, data is clocked on the rising edge of SCK.
When reading data from the ATmega163, data is clocked on the falling edge of SCK.
See Figure 87, Figure 88 and Table 62 for timing details.
To program and verify the ATmega163 in the serial programming mode, the following
sequence is recommended (See four byte instruction formats in Table 61):
1. Power-up sequence:
Apply power between VCC and GND while RESET and SCK are set to “0”. In accordance with the setting of CKSEL Fuses, apply a crystal/resonator, external clock, or
RC network, or let the device run on the internal RC Oscillator. In some systems,
the programmer can not guarantee that SCK is held low during power-up. In this
case, wait for 100 ms after SCK has been set to “0”. RESET must be then given a
positive pulse of at least two XTAL1 cycles duration and then set to “0”.
2. Wait for at least 20 ms and enable serial programming by sending the Programming Enable serial instruction to pin MOSI/PB5.
3. The Serial Programming instructions will not work if the communication is out of
synchronization. When in sync. the second byte ($53), will echo back when issuing the third byte of the Programming Enable instruction. Whether the echo is
correct or not, all four bytes of the instruction must be transmitted. If the $53 did
not echo back, give SCK a positive pulse and issue a new Programming Enable
command. If the $53 is not seen within 32 attempts, there is no functional device
connected.
4. If a Chip Erase is performed (must be done to erase the Flash), wait 2•tWD_FLASH
after the instruction, give RESET a positive pulse, and start over from Step 2.
See Table 60 for the tWD_FLASH figure.
5. The Flash is programmed one page at a time. The memory page is loaded one
byte at a time by supplying the 6 LSB of the address and data together with the
Load Program Memory Page instruction. The Program Memory Page is stored
by loading the Write Program Memory Page instruction with the 7 MSB of the
address. If polling is not used, the user must wait at least tWD_FLASH before issuing the next page. (Please refer to Table 60). Accessing the serial programming
interface before the Flash write operation completes can result in incorrect
programming.
6. The EEPROM array is programmed one byte at a time by supplying the address
and data together with the appropriate Write instruction. An EEPROM memory
location is first automatically erased before new data is written. If polling is not
used, the user must wait at least tWD_EEPROM before issuing the next byte. (Please
refer to Table 60). In a chip erased device, no $FFs in the data file(s) need to be
programmed.
7. Any memory location can be verified by using the Read instruction which returns
the content at the selected address at serial output MISO/PB6.
8. At the end of the programming session, RESET can be set high to commence
normal operation.
9. Power-off sequence (if needed):
Set XTAL1 to “0” (if external clock is used).
Set RESET to “1”.
Turn VCC power-off.
155
1142E–AVR–02/03
Data Polling Flash
When a page is being programmed into the Flash, reading an address location within
the page being programmed will give the value $FF. At the time the device is ready for a
new page, the programmed value will read correctly. This is used to determine when the
next page can be written. Note that the entire page is written simultaneously and any
address within the page can be used for polling. Data polling of the Flash will not work
for the value $FF, so when programming this value, the user will have to wait for at least
tWD_FLASH before programming the next page. As a chip-erased device contains $FF in
all locations, programming of addresses that are meant to contain $FF, can be skipped.
See Table 60 for tWD_FLASH value.
Data Polling EEPROM
When a new byte has been written and is being programmed into EEPROM, reading the
address location being programmed will give the value $FF. At the time the device is
ready for a new byte, the programmed value will read correctly. This is used to determine when the next byte can be written. This will not work for the value $FF, but the user
should have the following in mind: As a chip-erased device contains $FF in all locations,
programming of addresses that are meant to contain $FF, can be skipped. This does
not apply if the EEPROM is re-programmed without chip-erasing the device. In this
case, data polling cannot be used for the value $FF, and the user will have to wait at
least tWD_EEPROM before programming the next byte. See Table 60 for tWD_EEPROM value.
Programming Times for Nonvolatile Memory
The internal RC Oscillator is used to control programming time when programming or
erasing Flash, EEPORM, Fuses, and Lock bits. During Parallel or Serial Programming,
the device is in reset, and this Oscillator runs at its initial, uncalibrated frequency, which
may vary from 0.5 MHz to 1.0 MHz. In software it is possible to calibrate this Oscillator to
1.0 MHz (see “Calibrated Internal RC Oscillator” on page 37). Consequently, programming times will be shorter and more accurate when Programming or erasing non-volatile
memory from software, using SPM or the EEPROM interface. See Table 60 for a summary of programming times.
Table 60. Maximum Programming Times for Non-volatile Memory
2.7V
5.0V
SelfProgramming(1)
Operation
Symbol
Chip Erase
tWD_CE
16K
32 ms
30 ms
17 ms
Flash
Write(3)
tWD_FLASH
8K
16 ms
15 ms
8.5 ms
EEPROM
Write(2)
tWD_EEPROM
2K
4 ms
3.8 ms
2.2 ms
Fuse/lock bit
write
tWD_FUSE
1K
2 ms
1.9 ms
1.1 ms
Notes:
156
Parallel/Serial
Programming
Number of
RC
Oscillator
Cycles
1. Includes variation over voltage and temperature after RC Oscillator has been calibrated to 1.0 MHz
2. Parallel EEPROM Programming takes 1K cycles
3. Per page
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Figure 87. Serial Programming Waveforms
SERIAL DATA INPUT
PB5 (MOSI)
MSB
LSB
SERIAL DATA OUTPUT
PB6 (MISO)
MSB
LSB
SERIAL CLOCK INPUT
PB7(SCK)
SAMPLE
157
1142E–AVR–02/03
.
Table 61. Serial Programming Instruction Set
Instruction Format
Instruction
Byte 1
Byte 2
Byte 3
Byte4
Programming Enable
1010 1100
0101 0011
xxxx xxxx
xxxx xxxx
Enable Serial Programming after
RESET goes low.
Chip Erase
1010 1100
100x xxxx
xxxx xxxx
xxxx xxxx
Chip Erase EEPROM and Flash.
Read Program Memory
0010 H000
xxxa aaaa
bbbb bbbb
oooo oooo
Read H (high or low) data o from
Program memory at word address a:b.
Load Program Memory Page
0100 H000
xxxx xxxx
xxbb bbbb
iiii iiii
Write H (high or low) data i to Program
Memory page at word address b.
Write Program Memory Page
0100 1100
xxxa aaaa
bbxx xxxx
xxxx xxxx
Write Program Memory Page at
address a:b.
Read EEPROM Memory
1010 0000
xxxx xxxa
bbbb bbbb
oooo oooo
Read data o from EEPROM memory at
address a:b.
Write EEPROM Memory
1100 0000
xxxx xxxa
bbbb bbbb
iiii iiii
Write data i to EEPROM memory at
address a:b.
Read Lock Bits
0101 1000
0000 0000
xxxx 0xxx
xx65 4321
Read Lock bits. “0” = programmed, “1”
= unprogrammed.
Write Lock Bits
1010 1100
111x xxxx
xxxx xxxx
1165 4321
Write Lock bits. Set bits 6 - 1 = “0” to
program Lock bits.
Read Signature Byte
0011 0000
xxxx xxxx
xxxx xxbb
oooo oooo
Read Signature Byte o at address b.
Write Fuse Bits
1010 1100
1010 0000
xxxx xxxx
CB11 A987
Set bits C - A, 9 - 7 = “0” to program,
“1” to unprogram
Write Fuse High Bits
1010 1100
1010 1000
xxxx xxxx
1111 1FED
Set bits F - D = “0” to program, “1” to
unprogram
Read Fuse Bits
0101 0000
0000 0000
xxxx xxxx
CBxx A987
Read Fuse bits. “0” = programmed,
“1” = unprogrammed
Read Fuse High Bits
0101 1000
0000 1000
xxxx xxxx
xxxx 1FED
Read Fuse high bits. “0” = programmed, “1” = unprogrammed
Read Calibration Byte
0011 1000
xxxx xxxx
0000 0000
oooo oooo
Read Signature Byte o at address b.
Note:
158
Operation
a = address high bits, b = address low bits, H = 0 - Low byte, 1 - High Byte, o = data out, i = data in, x = don’t care
1 = lock bit 1, 2 = lock bit 2, 3 = Boot Lock Bit01, 4 = Boot Lock Bit02, 5 = Boot Lock Bit11, 6 = Boot Lock Bit12, 7 = CKSEL0
Fuse, 8 = CKSEL1 Fuse, 9 = CKSEL2 Fuse, A = CKSEL3 Fuse, B= BODEN Fuse, C= BODLEVEL Fuse, D= BOOTRST Fuse,
E= BOOTSZ0 Fuse, F= BOOTSZ1 Fuse
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Serial Programming
Characteristics
Figure 88. Serial Programming Timing
MOSI
tSHOX
tOVSH
SCK
tSLSH
tSHSL
MISO
tSLIV
Table 62. Serial Programming Characteristics, TA = -40°C to 85°C, VCC = 2.7V - 5.5V
(Unless otherwise noted)
Symbol
Parameter
1/tCLCL
Oscillator Frequency (VCC = 2.7 - 5.5 V)
tCLCL
1/tCLCL
Oscillator Period (VCC = 2.7 - 5.5 V)
Oscillator Frequency (VCC = 4.0 - 5.5 V)
tCLCL
Oscillator Period (VCC = 4.0 - 5.5 V)
tSHSL
Min
Typ
0
Max
Units
4
MHz
250
ns
0
8
MHz
125
ns
SCK Pulse Width High
2 tCLCL
ns
tSLSH
SCK Pulse Width Low
2 tCLCL
ns
tOVSH
MOSI Setup to SCK High
tCLCL
ns
tSHOX
MOSI Hold after SCK High
2 tCLCL
ns
tSLIV
SCK Low to MISO Valid
10
16
32
ns
159
1142E–AVR–02/03
Electrical Characteristics
Absolute Maximum Ratings*
Operating Temperature ................................. -55°C to +125°C
*NOTICE:
Storage Temperature .................................... -65°C to +150°C
Voltage on any Pin except RESET
with respect to Ground ................................-1.0V to VCC +0.5V
Voltage on RESET with respect to Ground .....-1.0V to +13.0V
Stresses beyond those listed under “Absolute
Maximum Ratings” 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.
Maximum Operating Voltage ............................................ 6.6V
DC Current per I/O Pin ............................................... 40.0 mA
DC Current VCC and GND Pins................................ 200.0 mA
DC Characteristics
TA = -40°C to 85°C, VCC = 2.7V to 5.5V (unless otherwise noted)
Symbol
Parameter
Condition
Min
VIL
Input Low-voltage
(Except XTAL1)
VIL1
VIH
VIH1
VIH2
Typ
Max
Units
-0.5
0.3 VCC(1)
V
(XTAL1), CKSEL3 fuse
programmed
-0.5
0.3 VCC(1)
V
(XTAL1), CKSEL3 fuse
unprogrammed
-0.5
0.2 VCC(1)
V
(Except XTAL1, RESET)
0.6 VCC(2)
VCC + 0.5
V
(XTAL1), CKSEL3 fuse
programmed
0.6 VCC(2)
VCC + 0.5
V
(XTAL1), CKSEL3 fuse
unprogrammed
0.8 VCC(2)
VCC + 0.5
V
(RESET)
0.9 VCC(2)
VCC + 0.5
V
0.6
0.5
V
V
Input Low-voltage
Input High-voltage
Input High-voltage
Input High-voltage
(3)
VOL
Output Low-voltage
(Ports A,B,C,D)
VOH
Output High-voltage(4)
(Ports A,B,C,D)
IOH = -3 mA, VCC = 5V
IOH = -1.5 mA, VCC = 3V
IIL
Input Leakage
Current I/O pin
Vcc = 5.5V, pin low
(absolute value)
8.0
µA
IIH
Input Leakage
Current I/O pin
Vcc = 5.5V, pin high
(absolute value)
980
nA
RRST
Reset Pull-up Resistor
100
500
kΩ
RI/O
I/O Pin Pull-up Resistor
35
120
kΩ
160
IOL = 20 mA, V CC = 5V
IOL = 10 mA, V CC = 3V
4.2
2.3
V
V
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
DC Characteristics
(Continued)
TA = -40°C to 85°C, VCC = 2.7V to 5.5V (unless otherwise noted)
Symbol
Parameter
Condition
Min
Typ
Max
Units
Active 4 MHz, VCC = 3V
(ATmega163L)
5.0
mA
Active 8 MHz, VCC = 5V
(ATmega163)
15.0
mA
Idle 4 MHz, VCC = 3V
(ATmega163L)
2.5
mA
Idle 8 MHz, VCC = 5V
(ATmega163)
8
mA
Power Supply Current
ICC
Power-down mode(5)
WDT enabled, VCC = 3V
9
15.0
µA
WDT disabled, VCC = 3V
<1
4.0
µA
40
mV
50
nA
VACIO
Analog Comparator
Input Offset Voltage
VCC = 5V
Vin = VCC/2
IACLK
Analog Comparator
Input Leakage Current
VCC = 5V
Vin = VCC/2
tACID
Analog Comparator
Initialization Delay
VCC = 2.7V
VCC = 4.0V
Notes:
-50
750
500
ns
1. “Max” means the highest value where the pin is guaranteed to be read as low
2. “Min” means the lowest value where the pin is guaranteed to be read as high
3. Although each I/O port can sink more than the test conditions (20 mA at Vcc = 5V, 10 mA at Vcc = 3V) under steady state
conditions (non-transient), the following must be observed:
1] The sum of all IOL, for all ports, should not exceed 200 mA.
2] The sum of all IOL, for ports B0 - B7, D0 - D7 and XTAL2, should not exceed 100 mA.
3] The sum of all IOL, for ports A0 - A7 and C0 - C7 should not exceed 100 mA.
If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater
than the listed test condition.
4. Although each I/O port can source more than the test conditions (3 mA at Vcc = 5V, 1.5 mA at Vcc = 3V) under steady state
conditions (non-transient), the following must be observed:
1] The sum of all IOH, for all ports, should not exceed 200 mA.
2] The sum of all IOH, for ports B0 - B7, D0 - D7 and XTAL2, should not exceed 100 mA.
3] The sum of all IOH, for ports A0 - A7 and C0 - C7 should not exceed 100 mA.
If IOH exceeds the test condition, VOH may exceed the related specification. Pins are not guaranteed to source current
greater than the listed test condition.
5. Minimum VCC for Power-down is 2.5V.
External Clock Drive
Waveforms
Figure 89. External Clock Drive Waveforms
161
1142E–AVR–02/03
External Clock Drive
Table 63. External Clock Drive
VCC = 2.7V to 5.5V
VCC = 4.0V to 5.5V
Symbol
Parameter
1/tCLCL
Oscillator Frequency
tCLCL
Clock Period
250
125
ns
tCHCX
High Time
100
50
ns
tCLCX
Low Time
100
50
ns
tCLCH
Rise Time
1.6
0.5
µs
tCHCL
Fall Time
1.6
0.5
µs
Min
Max
Min
Max
Units
0
4
0
8
MHz
Table 64. External RC Oscillator, typical frequencies
Note:
162
R [kΩ]
C [pF]
f
100
70
100 kHz
31.5
20
1.0 MHz
6.5
20
4.0 MHz
R should be in the range 3kΩ - 100kΩ, and C should be at least 20pF. The C values
given in the table includes pin capacitance. This will vary with package type.
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Two-wire Serial Interface Characteristics
Table 65 describes the requirements for devices connected to the Two-wire Serial Bus. The ATmega163 Two-wire Serial
Interface meets or exceeds these requirements under the noted conditions.
Timing symbols refer to Figure 90.
Table 65. Two-wire Serial Bus Requirements
Symbol
Parameter
VIL
Min
Max
Units
Input Low-voltage
-0.5
0.3 VCC
V
VIH
Input High-voltage
0.7 VCC
VCC + 0.5
V
Vhys(1)
Hysteresis of Schmitt Trigger Inputs
0.05 VCC(2)
–
V
0
0.4
V
250
ns
(2)
ns
VOL
(1)
Output Low-voltage
tof(1)
3 mA sink current
Output Fall Time from VIHmin to VILmax
tSP(1)
Spikes Suppressed by Input Filter
Ii
Input Current each I/O Pin
Ci(1)
Capacitance for each I/O Pin
fSCL
SCL Clock Frequency
tHD;STA
Hold Time (repeated) START Condition
10 pF < Cb < 400 pF
Low Period of the SCL Clock
tHIGH
High period of the SCL clock
tSU;STA
Set–up time for a repeated START condition
tHD;DAT
Data hold time
tSU;DAT
Data setup time
tSU;STO
Setup time for STOP condition
Bus free time between a STOP and START
condition
tBUF
(3)
20 + 0.1Cb
0
0.1VCC < V i < 0.9VCC
fCK
(4)
(3)(2)
50
-10
10
µA
–
10
pF
0
217
kHz
fSCL ≤ 100 kHz
4.0
–
µs
fSCL > 100 kHz
0.6
–
µs
4.7
–
µs
fSCL > 100 kHz
1.3
–
µs
fSCL ≤ 100 kHz
4.0
–
µs
fSCL > 100 kHz
0.6
–
µs
fSCL ≤ 100 kHz
4.7
–
µs
fSCL > 100 kHz
0.6
–
µs
fSCL ≤ 100 kHz
0
3.45
µs
fSCL > 100 kHz
0
0.9
µs
fSCL ≤ 100 kHz
250
–
ns
fSCL > 100 kHz
100
–
ns
fSCL ≤ 100 kHz
4.0
–
µs
fSCL > 100 kHz
0.6
–
µs
fSCL ≤ 100 kHz
4.7
–
µs
fSCL > 100 kHz
1.3
–
µs
> max(16fSCL, 250kHz)
fSCL ≤ 100 kHz
tLOW
Notes:
Condition
(6)
(5)
1.
2.
3.
4.
5.
In ATmegan163, this parameter is characterized and not 100% tested.
Required only for fSCL > 100 kHz.
Cb = capacitance of one bus line in pF.
fCK = CPU clock frequency
This requirement applies to all ATmega163 Two-wire Serial Interface operation. Other devices connected to the Two-wire
Serial Bus need only obey the general fSCL requirement.
6. The actual low period generated by the ATmega163 Two-wire Serial Interface is (1/fSCL - 2/fCK), thus fCK must be greater than
6 MHz for the low time requirement to be strictly met at fSCL = 100 kHz.
163
1142E–AVR–02/03
Figure 90. Two-wire Serial Bus Timing
tof
tHIGH
tLOW
tLOW
SCL
tSU;STA
tHD;STA
tHD;DAT
tSU;DAT
tSU;STO
SDA
tBUF
164
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Typical
Characteristics
The following charts show typical behavior. These figures are not tested during manufacturing. All current consumption measurements are performed with all I/O pins
configured as inputs and with internal pull-ups enabled. All pins on Port F are pulled high
externally. A sine wave generator with rail-to-rail output is used as clock source.
The power consumption in Power-down mode is independent of clock selection.
The current consumption is a function of several factors such as: operating voltage,
operating frequency, loading of I/O pins, switching rate of I/O pins, code executed and
ambient temperature. The dominating factors are operating voltage and frequency.
The current drawn from capacitive loaded pins may be estimated (for one pin) as CL •
VCC • f, where CL = load capacitance, VCC = operating voltage and f = average switching
frequency of I/O pin.
The parts are characterized at frequencies higher than test limits. Parts are not guaranteed to function properly at frequencies higher than the ordering code indicates.
The difference between current consumption in Power-down mode with Watchdog
Timer enabled and Power-down mode with Watchdog Timer disabled represents the differential current drawn by the Watchdog Timer.
Figure 91. Analog Comparator Offset Voltage vs, Common Mode Voltage (VCC = 5V)
18
16
TA = 25˚C
Offset Voltage (mV)
14
12
TA = 85˚C
10
8
6
4
2
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Common Mode Voltage (V)
165
1142E–AVR–02/03
Figure 92. Analog Comparator Offset Voltage vs. Common Mode Voltage (VCC = 2.7V)
10
TA = 25˚C
Offset Voltage (mV)
8
6
TA = 85˚C
4
2
0
0
0.5
1
1.5
2
2.5
3
Common Mode Voltage (V)
Figure 93. Analog Comparator Input Leakage Current (VCC = 6V; TA = 25°C)
60
50
30
I
ACLK
(nA)
40
20
10
0
-10
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
VIN (V)
166
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Figure 94. Watchdog Oscillator Frequency vs. VCC
1600
TA = 25˚C
1400
TA = 85˚C
F RC (KHz)
1200
1000
800
600
400
200
0
2
2.5
3
3.5
4
4.5
5
5.5
6
Vcc (V)
Sink and source capabilities of I/O ports are measured on one pin at a time.
Figure 95. Pull-up Resistor Current vs. Input Voltage (VCC = 5V)
120
TA = 25˚C
100
TA = 85˚C
I
OP (µA)
80
60
40
20
0
0
0.5
1
1.5
2
2.5
VOP (V)
3
3.5
4
4.5
5
167
1142E–AVR–02/03
Figure 96. Pull-up Resistor Current vs. Input Voltage (VCC = 2.7V)
30
TA = 25˚C
25
TA = 85˚C
15
I
OP (µA)
20
10
5
0
0
0.5
1
1.5
2
2.5
3
2.5
3
VOP (V)
Figure 97. I/O Pin Sink Current vs. Output Voltage (VCC = 5V)
70
TA = 25˚C
60
TA = 85˚C
50
30
I
OL (mA)
40
20
10
0
0
0.5
1
1.5
2
VOL (V)
168
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Figure 98. I/O Pin Source Current vs. Output Voltage (VCC = 5V)
20
TA = 25˚C
18
16
TA = 85˚C
14
I
OH (mA)
12
10
8
6
4
2
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
VOH (V)
Figure 99. I/O Pin Sink Current vs. Output Voltage (VCC = 2.7V)
25
TA = 25˚C
20
TA = 85˚C
10
I
OL (mA)
15
5
0
0
0.5
1
1.5
2
VOL (V)
169
1142E–AVR–02/03
Figure 100. I/O Pin Source Current vs. Output Voltage (VCC = 2.7V)
6
TA = 25˚C
5
TA = 85˚C
3
I
OH (mA)
4
2
1
0
0
0.5
1
1.5
2
2.5
3
VOH (V)
Figure 101. I/O Pin Input Threshold vs. VCC (TA = 25°C)
2.5
Threshold Voltage (V)
2
1.5
1
0.5
0
2.7
4.0
5.0
Vcc
170
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Figure 102. I/O Pin Input Hysteresis vs. VCC (TA = 25°C)
0.18
0.16
Input hysteresis (V)
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
2.7
4.0
5.0
Vcc
171
1142E–AVR–02/03
Register Summary
Address
Name
$3F ($5F)
$3E ($5E)
$3D ($5D)
$3C ($5C)
$3B ($5B)
$3A ($5A)
$39 ($59)
$38 ($58)
$37 ($57)
$36 ($56)
$35 ($55)
$34 ($54)
$33 ($53)
$32 ($52)
$31 ($51)
$30 ($50)
$2F ($4F)
$2E ($4E)
$2D ($4D)
$2C ($4C)
$2B ($4B)
$2A ($4A)
$29 ($49)
$28 ($48)
$27 ($47)
$26 ($46)
$25 ($45)
$24 ($44)
$23 ($43)
$22 ($42)
$21 ($41)
$20 ($40)
$1F ($3F)
$1E ($3E)
$1D ($3D)
$1C ($3C)
$1B ($3B)
$1A ($3A)
$19 ($39)
$18 ($38)
$17 ($37)
$16 ($36)
$15 ($35)
$14 ($34)
$13 ($33)
$12 ($32)
$11 ($31)
$10 ($30)
$0F ($2F)
$0E ($2E)
$0D ($2D)
$0C ($2C)
$0B ($2B)
$0A ($2A)
$09 ($29)
$08 ($28)
$07 ($27)
$06 ($26)
$05 ($25)
$04 ($24)
$03 ($23)
$02 ($22)
$01 ($21)
SREG
SPH
SPL
Reserved
GIMSK
GIFR
TIMSK
TIFR
SPMCR
TWCR
MCUCR
MCUSR
TCCR0
TCNT0
OSCCAL
SFIOR
TCCR1A
TCCR1B
TCNT1H
TCNT1L
OCR1AH
OCR1AL
OCR1BH
OCR1BL
ICR1H
ICR1L
TCCR2
TCNT2
OCR2
ASSR
WDTCR
UBRRHI
EEARH
EEARL
EEDR
EECR
PORTA
DDRA
PINA
PORTB
DDRB
PINB
PORTC
DDRC
PINC
PORTD
DDRD
PIND
SPDR
SPSR
SPCR
UDR
UCSRA
UCSRB
UBRR
ACSR
ADMUX
ADCSR
ADCH
ADCL
TWDR
TWAR
TWSR
172
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Page
I
–
SP7
T
–
SP6
H
–
SP5
S
–
SP4
V
–
SP3
N
SP10
SP2
Z
SP9
SP1
C
SP8
SP0
20
21
21
–
–
OCIE1B
OCF1B
BLBSET
TWWC
ISC11
WDRF
–
–
–
TOIE1
TOV1
PGWRT
TWEN
ISC10
BORF
CS02
–
–
–
–
PGERS
–
ISC01
EXTRF
CS01
–
–
TOIE0
TOV0
SPMEN
TWIE
ISC00
PORF
CS00
ACME
FOC1A
CTC1
PUD
FOC1B
CS12
PSR2
PWM11
CS11
PSR10
PWM10
CS10
CTC2
CS22
CS21
CS20
30
31
32
32
140
82
34
28
41
42
37
40
44
45
46
46
47
47
47
47
48
48
52
53
54
57
60
78
62
62
62
63
115
115
115
117
117
117
123
123
123
128
128
128
69
68
67
74
74
76
78
102
110
111
112
112
84
85
84
INT1
INT0
–
–
INTF1
INTF0
–
–
OCIE2
TOIE2
TICIE1
OCIE1A
OCF2
TOV2
ICF1
OCF1A
–
ASB
–
ASRE
TWINT
TWEA
TWSTA
TWSTO
–
SE
SM1
SM0
–
–
–
–
–
–
–
–
Timer/Counter0 (8 Bits)
Oscillator Calibration Register
–
–
–
–
COM1A1
COM1A0
COM1B1
COM1B0
ICNC1
ICES1
–
–
Timer/Counter1 – Counter Register High Byte
Timer/Counter1 – Counter Register Low Byte
Timer/Counter1 – Output Compare Register A High Byte
Timer/Counter1 – Output Compare Register A Low Byte
Timer/Counter1 – Output Compare Register B High Byte
Timer/Counter1 – Output Compare Register B Low Byte
Timer/Counter1 – Input Capture Register High Byte
Timer/Counter1 – Input Capture Register Low Byte
FOC2
PWM2
COM21
COM20
Timer/Counter2 (8 Bits)
Timer/Counter2 Output Compare Register
–
–
–
–
–
–
–
WDTOE
–
–
–
–
–
–
–
–
EEAR7
EEAR6
EEAR5
EEAR4
EEPROM Data Register
–
–
–
–
PORTA7
PORTA6
PORTA5
PORTA4
DDA7
DDA6
DDA5
DDA4
PINA7
PINA6
PINA5
PINA4
PORTB7
PORTB6
PORTB5
PORTB4
DDB7
DDB6
DDB5
DDB4
PINB7
PINB6
PINB5
PINB4
PORTC7
PORTC6
PORTC5
PORTC4
DDC7
DDC6
DDC5
DDC4
PINC7
PINC6
PINC5
PINC4
PORTD7
PORTD6
PORTD5
PORTD4
DDD7
DDD6
DDD5
DDD4
PIND7
PIND6
PIND5
PIND4
SPI Data Register
SPIF
WCOL
–
–
SPIE
SPE
DORD
MSTR
UART I/O Data Register
RXC
TXC
UDRE
FE
RXCIE
TXCIE
UDRIE
RXEN
UART Baud Rate Register
ACD
ACBG
ACO
ACI
REFS1
REFS0
ADLAR
MUX4
ADEN
ADSC
ADFR
ADIF
ADC Data Register High Byte
ADC Data Register Low Byte
Two-wire Serial Interface Data Register
TWA6
TWA5
TWA4
TWA3
TWS7
TWS6
TWS5
TWS4
AS2
WDE
TCN2UB
OCR2UB
WDP2
WDP1
UBRR[11:8]
–
–
EEAR2
EEAR1
TCR2UB
WDP0
EERIE
PORTA3
DDA3
PINA3
PORTB3
DDB3
PINB3
PORTC3
DDC3
PINC3
PORTD3
DDD3
PIND3
EEMWE
PORTA2
DDA2
PINA2
PORTB2
DDB2
PINB2
PORTC2
DDC2
PINC2
PORTD2
DDD2
PIND2
EEWE
PORTA1
DDA1
PINA1
PORTB1
DDB1
PINB1
PORTC1
DDC1
PINC1
PORTD1
DDD1
PIND1
EERE
PORTA0
DDA0
PINA0
PORTB0
DDB0
PINB0
PORTC0
DDC0
PINC0
PORTD0
DDD0
PIND0
–
CPOL
–
CPHA
–
SPR1
SPI2X
SPR0
OR
TXEN
–
CHR9
U2X
RXB8
MPCM
TXB8
ACIE
MUX3
ADIE
ACIC
MUX2
ADPS2
ACIS1
MUX1
ADPS1
ACIS0
MUX0
ADPS0
TWA2
TWS3
TWA1
–
TWA0
–
TWGCE
–
–
EEAR3
EEAR8
EEAR0
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Register Summary (Continued)
Address
$00 ($20)
Note:
Name
TWBR
Bit 7
Bit 6
Bit 5
Two-wire Serial Interface Bit Rate Register
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Page
82
1. For compatibility with future devices, reserved bits should be written to zero if accessed. Reserved I/O memory addresses
should never be written.
2. Some of the Status Flags are cleared by writing a logical one to them. Note that the CBI and SBI instructions will operate on
all bits in the I/O Register, writing a one back into any flag read as set, thus clearing the flag. The CBI and SBI instructions
work with registers $00 to $1F only.
173
1142E–AVR–02/03
Instruction Set Summary
Mnemonics
Operands
Description
ARITHMETIC AND LOGIC INSTRUCTIONS
ADD
Rd, Rr
Add two Registers
ADC
Rd, Rr
Add with Carry two Registers
ADIW
Rdl,K
Add Immediate to Word
SUB
Rd, Rr
Subtract two Registers
SUBI
Rd, K
Subtract Constant from Register
SBC
Rd, Rr
Subtract with Carry two Registers
SBCI
Rd, K
Subtract with Carry Constant from Reg.
SBIW
Rdl,K
Subtract Immediate from Word
AND
Rd, Rr
Logical AND Registers
ANDI
Rd, K
Logical AND Register and Constant
OR
Rd, Rr
Logical OR Registers
ORI
Rd, K
Logical OR Register and Constant
EOR
Rd, Rr
Exclusive OR Registers
COM
Rd
One’s Complement
NEG
Rd
Two’s Complement
SBR
Rd,K
Set Bit(s) in Register
CBR
Rd,K
Clear Bit(s) in Register
INC
Rd
Increment
DEC
Rd
Decrement
TST
Rd
Test for Zero or Minus
CLR
Rd
Clear Register
SER
Rd
Set Register
MUL
Rd, Rr
Multiply Unsigned
MULS
Rd, Rr
Multiply Signed
MULSU
Rd, Rr
Multiply Signed with Unsigned
FMUL
Rd, Rr
Fractional Multiply Unsigned
FMULS
Rd, Rr
Fractional Multiply Signed
FMULSU
Rd, Rr
Fractional Multiply Signed with Unsigned
BRANCH INSTRUCTIONS
RJMP
k
Relative Jump
IJMP
Indirect Jump to (Z)
JMP
k
Direct Jump
RCALL
k
Relative Subroutine Call
ICALL
Indirect Call to (Z)
CALL
k
Direct Subroutine Call
RET
Subroutine Return
RETI
Interrupt Return
CPSE
Rd,Rr
Compare, Skip if Equal
CP
Rd,Rr
Compare
CPC
Rd,Rr
Compare with Carry
CPI
Rd,K
Compare Register with Immediate
SBRC
Rr, b
Skip if Bit in Register Cleared
SBRS
Rr, b
Skip if Bit in Register is Set
SBIC
P, b
Skip if Bit in I/O Register Cleared
SBIS
P, b
Skip if Bit in I/O Register is Set
BRBS
s, k
Branch if Status Flag Set
BRBC
s, k
Branch if Status Flag Cleared
BREQ
k
Branch if Equal
BRNE
k
Branch if Not Equal
BRCS
k
Branch if Carry Set
BRCC
k
Branch if Carry Cleared
BRSH
k
Branch if Same or Higher
BRLO
k
Branch if Lower
BRMI
k
Branch if Minus
BRPL
k
Branch if Plus
BRGE
k
Branch if Greater or Equal, Signed
BRLT
k
Branch if Less Than Zero, Signed
BRHS
k
Branch if Half Carry Flag Set
BRHC
k
Branch if Half Carry Flag Cleared
BRTS
k
Branch if T Flag Set
BRTC
k
Branch if T Flag Cleared
BRVS
k
Branch if Overflow Flag is Set
BRVC
k
Branch if Overflow Flag is Cleared
174
Operation
Flags
#Clocks
Rd ← Rd + Rr
Rd ← Rd + Rr + C
Rdh:Rdl ← Rdh:Rdl + K
Rd ← Rd - Rr
Rd ← Rd - K
Rd ← Rd - Rr - C
Rd ← Rd - K - C
Rdh:Rdl ← Rdh:Rdl - K
Rd ← Rd • Rr
Rd ← Rd • K
Rd ← Rd v Rr
Rd ← Rd v K
Rd ← Rd ⊕ Rr
Rd ← $FF − Rd
Rd ← $00 − Rd
Rd ← Rd v K
Rd ← Rd • ($FF - K)
Rd ← Rd + 1
Rd ← Rd − 1
Rd ← Rd • Rd
Rd ← Rd ⊕ Rd
Rd ← $FF
R1:R0 ← Rd x Rr
R1:R0 ← Rd x Rr
R1:R0 ← Rd x Rr
R1:R0 ← (Rd x Rr) << 1
R1:R0 ← (Rd x Rr) << 1
R1:R0 ← (Rd x Rr) << 1
Z,C,N,V,H
Z,C,N,V,H
Z,C,N,V,S
Z,C,N,V,H
Z,C,N,V,H
Z,C,N,V,H
Z,C,N,V,H
Z,C,N,V,S
Z,N,V
Z,N,V
Z,N,V
Z,N,V
Z,N,V
Z,C,N,V
Z,C,N,V,H
Z,N,V
Z,N,V
Z,N,V
Z,N,V
Z,N,V
Z,N,V
None
Z,C
Z,C
Z,C
Z,C
Z,C
Z,C
1
1
2
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
PC ← PC + k + 1
PC ← Z
PC ← k
PC ← PC + k + 1
PC ← Z
PC ← k
PC ← STACK
PC ← STACK
if (Rd = Rr) PC ← PC + 2 or 3
Rd − Rr
Rd − Rr − C
Rd − K
if (Rr(b)=0) PC ← PC + 2 or 3
if (Rr(b)=1) PC ← PC + 2 or 3
if (P(b)=0) PC ← PC + 2 or 3
if (P(b)=1) PC ← PC + 2 or 3
if (SREG(s) = 1) then PC←PC+k + 1
if (SREG(s) = 0) then PC←PC+k + 1
if (Z = 1) then PC ← PC + k + 1
if (Z = 0) then PC ← PC + k + 1
if (C = 1) then PC ← PC + k + 1
if (C = 0) then PC ← PC + k + 1
if (C = 0) then PC ← PC + k + 1
if (C = 1) then PC ← PC + k + 1
if (N = 1) then PC ← PC + k + 1
if (N = 0) then PC ← PC + k + 1
if (N ⊕ V= 0) then PC ← PC + k + 1
if (N ⊕ V= 1) then PC ← PC + k + 1
if (H = 1) then PC ← PC + k + 1
if (H = 0) then PC ← PC + k + 1
if (T = 1) then PC ← PC + k + 1
if (T = 0) then PC ← PC + k + 1
if (V = 1) then PC ← PC + k + 1
if (V = 0) then PC ← PC + k + 1
None
None
None
None
None
None
None
I
None
Z, N,V,C,H
Z, N,V,C,H
Z, N,V,C,H
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
2
2
3
3
3
4
4
4
1/2/3
1
1
1
1/2/3
1/2/3
1/2/3
1/2/3
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Instruction Set Summary (Continued)
BRIE
k
BRID
k
DATA TRANSFER INSTRUCTIONS
MOV
Rd, Rr
MOVW
Rd, Rr
LDI
Rd, K
LD
Rd, X
LD
Rd, X+
LD
Rd, - X
LD
Rd, Y
LD
Rd, Y+
LD
Rd, - Y
LDD
Rd,Y+q
LD
Rd, Z
LD
Rd, Z+
LD
Rd, -Z
LDD
Rd, Z+q
LDS
Rd, k
ST
X, Rr
ST
X+, Rr
ST
- X, Rr
ST
Y, Rr
ST
Y+, Rr
ST
- Y, Rr
STD
Y+q,Rr
ST
Z, Rr
ST
Z+, Rr
ST
-Z, Rr
STD
Z+q,Rr
STS
k, Rr
LPM
LPM
Rd, Z
LPM
Rd, Z+
SPM
IN
Rd, P
OUT
P, Rr
PUSH
Rr
POP
Rd
BIT AND BIT-TEST INSTRUCTIONS
SBI
P,b
CBI
P,b
LSL
Rd
LSR
Rd
ROL
Rd
ROR
Rd
ASR
Rd
SWAP
Rd
BSET
s
BCLR
s
BST
Rr, b
BLD
Rd, b
SEC
CLC
SEN
CLN
SEZ
CLZ
SEI
CLI
SES
CLS
SEV
CLV
SET
CLT
SEH
Branch if Interrupt Enabled
Branch if Interrupt Disabled
if ( I = 1) then PC ← PC + k + 1
if ( I = 0) then PC ← PC + k + 1
None
None
1/2
1/2
Move Between Registers
Copy Register Word
Load Immediate
Load Indirect
Load Indirect and Post-Inc.
Load Indirect and Pre-Dec.
Load Indirect
Load Indirect and Post-Inc.
Load Indirect and Pre-Dec.
Load Indirect with Displacement
Load Indirect
Load Indirect and Post-Inc.
Load Indirect and Pre-Dec.
Load Indirect with Displacement
Load Direct from SRAM
Store Indirect
Store Indirect and Post-Inc.
Store Indirect and Pre-Dec.
Store Indirect
Store Indirect and Post-Inc.
Store Indirect and Pre-Dec.
Store Indirect with Displacement
Store Indirect
Store Indirect and Post-Inc.
Store Indirect and Pre-Dec.
Store Indirect with Displacement
Store Direct to SRAM
Load Program Memory
Load Program Memory
Load Program Memory and Post-Inc
Store Program Memory
In Port
Out Port
Push Register on Stack
Pop Register from Stack
Rd ← Rr
Rd+1:Rd ← Rr+1:Rr
Rd ← K
Rd ← (X)
Rd ← (X), X ← X + 1
X ← X - 1, Rd ← (X)
Rd ← (Y)
Rd ← (Y), Y ← Y + 1
Y ← Y - 1, Rd ← (Y)
Rd ← (Y + q)
Rd ← (Z)
Rd ← (Z), Z ← Z+1
Z ← Z - 1, Rd ← (Z)
Rd ← (Z + q)
Rd ← (k)
(X) ← Rr
(X) ← Rr, X ← X + 1
X ← X - 1, (X) ← Rr
(Y) ← Rr
(Y) ← Rr, Y ← Y + 1
Y ← Y - 1, (Y) ← Rr
(Y + q) ← Rr
(Z) ← Rr
(Z) ← Rr, Z ← Z + 1
Z ← Z - 1, (Z) ← Rr
(Z + q) ← Rr
(k) ← Rr
R0 ← (Z)
Rd ← (Z)
Rd ← (Z), Z ← Z+1
(Z) ← R1:R0
Rd ← P
P ← Rr
STACK ← Rr
Rd ← STACK
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
3
3
1
1
2
2
Set Bit in I/O Register
Clear Bit in I/O Register
Logical Shift Left
Logical Shift Right
Rotate Left Through Carry
Rotate Right Through Carry
Arithmetic Shift Right
Swap Nibbles
Flag Set
Flag Clear
Bit Store from Register to T
Bit load from T to Register
Set Carry
Clear Carry
Set Negative Flag
Clear Negative Flag
Set Zero Flag
Clear Zero Flag
Global Interrupt Enable
Global Interrupt Disable
Set Signed Test Flag
Clear Signed Test Flag
Set Twos Complement Overflow.
Clear Twos Complement Overflow
Set T in SREG
Clear T in SREG
Set Half Carry Flag in SREG
I/O(P,b) ← 1
I/O(P,b) ← 0
Rd(n+1) ← Rd(n), Rd(0) ← 0
Rd(n) ← Rd(n+1), Rd(7) ← 0
Rd(0)←C,Rd(n+1)← Rd(n),C←Rd(7)
Rd(7)←C,Rd(n)← Rd(n+1),C←Rd(0)
Rd(n) ← Rd(n+1), n=0..6
Rd(3..0)←Rd(7..4),Rd(7..4)←Rd(3..0)
SREG(s) ← 1
SREG(s) ← 0
T ← Rr(b)
Rd(b) ← T
C←1
C←0
N←1
N←0
Z←1
Z←0
I←1
I←0
S←1
S←0
V←1
V←0
T←1
T←0
H←1
None
None
Z,C,N,V
Z,C,N,V
Z,C,N,V
Z,C,N,V
Z,C,N,V
None
SREG(s)
SREG(s)
T
None
C
C
N
N
Z
Z
I
I
S
S
V
V
T
T
H
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
175
1142E–AVR–02/03
Instruction Set Summary (Continued)
CLH
NOP
SLEEP
WDR
176
Clear Half Carry Flag in SREG
No Operation
Sleep
Watchdog Reset
H←0
(see specific descr. for Sleep function)
(see specific descr. for WDR/timer)
H
None
None
None
1
1
1
1
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Ordering Information
Speed (MHz)
Power Supply
4
2.7 - 5.5V
8
4.0 - 5.5V
Ordering Code
Package
Operation Range
ATmega163L-4AC
ATmega163L-4PC
44A
40P6
Commercial
(0°C to 70°C)
ATmega163L-4AI
ATmega163L-4PI
44A
40P6
Industrial
(-40°C to 85°C)
ATmega163-8AC
ATmega163-8PC
44A
40P6
Commercial
(0°C to 70°C)
ATmega163-8AI
ATmega163-8PI
44A
40P6
Industrial
(-40°C to 85°C)
Package Type
44A
44-lead, Thin (1.0 mm) Plastic Gull Wing Quad Flat Package (TQFP)
40P6
40-lead, 0.600" Wide, Plastic Dual Inline Package (PDIP)
177
1142E–AVR–02/03
Packaging Information
44A
PIN 1
B
PIN 1 IDENTIFIER
E1
e
E
D1
D
C
0˚~7˚
A1
A2
A
L
COMMON DIMENSIONS
(Unit of Measure = mm)
Notes:
1. This package conforms to JEDEC reference MS-026, Variation ACB.
2. Dimensions D1 and E1 do not include mold protrusion. Allowable
protrusion is 0.25 mm per side. Dimensions D1 and E1 are maximum
plastic body size dimensions including mold mismatch.
3. Lead coplanarity is 0.10 mm maximum.
SYMBOL
MIN
NOM
MAX
A
–
–
1.20
A1
0.05
–
0.15
A2
0.95
1.00
1.05
D
11.75
12.00
12.25
D1
9.90
10.00
10.10
E
11.75
12.00
12.25
E1
9.90
10.00
10.10
B
0.30
–
0.45
C
0.09
–
0.20
L
0.45
–
0.75
e
NOTE
Note 2
Note 2
0.80 TYP
10/5/2001
R
178
2325 Orchard Parkway
San Jose, CA 95131
TITLE
44A, 44-lead, 10 x 10 mm Body Size, 1.0 mm Body Thickness,
0.8 mm Lead Pitch, Thin Profile Plastic Quad Flat Package (TQFP)
DRAWING NO. REV.
44A
B
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
40P6
D
PIN
1
E1
A
SEATING PLANE
A1
L
B1
B
e
E
COMMON DIMENSIONS
(Unit of Measure = mm)
0º ~ 15º REF
C
SYMBOL
eB
Notes:
1. This package conforms to JEDEC reference MS-011, Variation AC.
2. Dimensions D and E1 do not include mold Flash or Protrusion.
Mold Flash or Protrusion shall not exceed 0.25 mm (0.010").
MIN
NOM
MAX
A
–
–
4.826
A1
0.381
–
–
D
52.070
–
NOTE
52.578 Note 2
E
15.240
–
15.875
E1
13.462
–
13.970 Note 2
B
0.356
–
0.559
B1
1.041
–
1.651
L
3.048
–
3.556
C
0.203
–
0.381
eB
15.494
–
17.526
e
2.540 TYP
09/28/01
R
2325 Orchard Parkway
San Jose, CA 95131
TITLE
40P6, 40-lead (0.600"/15.24 mm Wide) Plastic Dual
Inline Package (PDIP)
DRAWING NO. REV.
40P6
B
179
1142E–AVR–02/03
Erratas
ATmega163(L) Errata
Rev. F
•
•
•
•
•
•
Increased Interrupt Latency
Interrupts Abort TWI Power-down
TWI Master Does not Accept Spikes on Bus Lines
TWCR Write Operations Ignored
PWM not Phase Correct
TWI is Speed Limited in Slave Mode
6. Increased Interrupt Latency
In this device, some instructions are not interruptable, and will cause the interrupt
latency to increase. The only practical problem concerns a loop followed by a twoword instruction while waiting for an interrupt. The loop may consist of a branch
instruction or an absolute or relative jump back to itself like this:
loop: rjmp loop
<Two-word instruction>
In this case, a dead-lock situation arises.
Problem Fix/Workaround
In assembly, insert a nop instruction immediately after a loop to itself. The problem
will normally be detected during development. In C, the only construct that will give
this problem is an empty “for” loop; “for(;;)”. Use “while(1)” or “do{} while (1)” to avoid
the problem.
5. Interrupts Abort TWI Power-down
TWI Power-down operation may be aborted by other interrupts. If an interrupt (e.g.,
INT0) occurs during TWI Power-down address watch and wakes the CPU up, the
TWI aborts operation and returns to its idle state.
Problem Fix/Workaround
Ensure that the TWI Address Match is the only enabled interrupt when entering
Power-down.
4. TWI Master Does not Accept Spikes on Bus Lines
When the part operates as Master, and the bus is idle (SDA = 1; SCL = 1), generating a short spike on SDA (SDA = 0 for a short interval), no interrupt is generated,
and the status code is still $F8 (idle). But when the software initiates a new start
condition and clears TWINT, nothing happens on SDA or SCL, and TWINT is never
set again.
Problem Fix/Workaround
Either of the following:
1. Ensure that no spikes occur on SDA or SCL lines.
2. Receiving a valid START condition followed by a STOP condition provokes a
bus error reported as a TWI interrupt with status code $00.
3. In a Single Master systems, the user should write the TWSTO bit immediately before writing the TWSTA bit.
3. TWCR Write Operation Ignored
Repeated write to TWCR must be delayed. If a write operation to TWCR is immediately followed by another write operation to TWCR, the first write operation may be
ignored.
180
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Problem Fix/Workaround
Ensure at least one instruction (e.g., nop) is executed between two writes to TWCR.
2. PWM not Phase Correct
In Phase-correct PWM mode, a change from OCRx = TOP to anything less than
TOP does not change the OCx output. This gives a phase error in the following
period.
Problem Fix/Workaround
Make sure this issue is not harmful to the application.
1. TWI is Speed Limited in Slave Mode
When the two-wire Serial Interface operates in Slave mode, frames may be undetected if the CPU frequency is less than 64 times the bus frequency.
Problem Fix/Workaround
Ensure that the CPU frequency is at least 64 times the TWI bus frequency.
181
1142E–AVR–02/03
Change Log
This section containes a log on the changes made to the data sheet for ATmega163. All
refereces to pages in Change Log, are referred to this document.
Changes from Rev.
1142C-09/01 to Rev.
1142D-09/02
1. Added “Not Recommend for New Designs. Use ATmega16.”.
Changes from Rev.
1142D-09/09 to Rev.
1142E-02/03
1. Updated Table 52, “Boot Reset Fuse,” on page 136.
2. Corrected pin numbers in Figure 62 on page 113.
3. Corrected a constant in the Boot Loader code example on page 141.
4. Changed max bit rate for the TWI from 400 kHz to 217 kHz.
5. Removed redundant and harmful loop in a code example for Slave Receiver
mode for the TWI on page 96.
6. Added AGND and AVCC in Figure 81 on page 145 and Figure 86 on page 154.
7. Updated the “Packaging Information” on page 178.
8. Added “Erratas” on page 180.
182
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Table of Contents
Features................................................................................................. 1
Pin Configurations................................................................................ 2
Description ............................................................................................ 3
Block Diagram....................................................................................... 3
Pin Descriptions.................................................................................................... 4
Clock Options ....................................................................................................... 5
Timer Oscillator..................................................................................................... 6
Architectural Overview......................................................................... 7
The General Purpose Register File ....................................................................
The ALU – Arithmetic Logic Unit.........................................................................
The In-System Self-Programmable Flash Program Memory..............................
The SRAM Data Memory....................................................................................
The Program and Data Addressing Modes ........................................................
The EEPROM Data Memory ..............................................................................
Memory Access Times and Instruction Execution Timing ..................................
I/O Memory .........................................................................................................
Reset and Interrupt Handling ..............................................................................
Sleep Modes.......................................................................................................
Calibrated Internal RC Oscillator ........................................................................
10
11
11
11
12
16
16
17
21
35
37
Timer/Counters ................................................................................... 39
Timer/Counter Prescalers ...................................................................................
8-bit Timer/Counter0...........................................................................................
16-bit Timer/Counter1.........................................................................................
8-bit Timer/Counter 2 ..........................................................................................
39
40
42
51
Watchdog Timer.................................................................................. 60
EEPROM Read/Write Access............................................................. 62
Preventing EEPROM Corruption ........................................................................ 64
Serial Peripheral Interface – SPI........................................................ 65
SS Pin Functionality............................................................................................ 66
Data Modes ........................................................................................................ 67
UART.................................................................................................... 70
Data Transmission..............................................................................................
Data Reception ...................................................................................................
UART Control .....................................................................................................
Double Speed Transmission...............................................................................
70
72
74
78
i
1142E–AVR–02/03
Two-wire Serial Interface (Byte Oriented) ........................................ 80
Two-wire Serial Interface Modes ........................................................................
Master Transmitter Mode....................................................................................
Master Receiver Mode........................................................................................
Slave Receiver Mode..........................................................................................
Slave Transmitter Mode......................................................................................
Miscellaneous States ..........................................................................................
85
86
86
87
88
88
The Analog Comparator................................................................... 102
Analog Comparator Multiplexed Input .............................................................. 104
Analog to Digital Converter ............................................................. 105
Feature List.......................................................................................................
Operation ..........................................................................................................
Prescaling and Conversion Timing ...................................................................
ADC Noise Canceler Function ..........................................................................
Scanning Multiple Channels .............................................................................
ADC Noise Canceling Techniques ...................................................................
ADC Characteristics .........................................................................................
105
106
107
109
113
113
114
I/O Ports............................................................................................. 115
Port A................................................................................................................
Port B................................................................................................................
Port C................................................................................................................
Port D................................................................................................................
115
117
123
128
Memory Programming...................................................................... 134
Boot Loader Support.........................................................................................
Self-Programming the Flash .............................................................................
Preventing Flash Corruption .............................................................................
Program and Data Memory Lock Bits...............................................................
Fuse Bits...........................................................................................................
Signature Bytes ................................................................................................
Calibration Byte ................................................................................................
Parallel Programming .......................................................................................
Parallel Programming Characteristics ..............................................................
Serial Downloading ...........................................................................................
Serial Programming Characteristics .................................................................
134
136
141
143
144
144
144
145
153
154
159
Electrical Characteristics................................................................. 160
Absolute Maximum Ratings*............................................................................. 160
External Clock Drive Waveforms .................................................... 161
External Clock Drive......................................................................... 162
ii
ATmega163(L)
1142E–AVR–02/03
ATmega163(L)
Two-wire Serial Interface Characteristics ...................................... 163
Typical Characteristics .................................................................... 165
Register Summary ............................................................................ 172
Instruction Set Summary ................................................................. 174
Ordering Information........................................................................ 177
Packaging Information ..................................................................... 178
44A ................................................................................................................... 178
40P6 ................................................................................................................. 179
Erratas ............................................................................................... 180
ATmega163(L) Errata Rev. F ........................................................................... 180
Change Log ....................................................................................... 182
Changes from Rev. 1142C-09/01 to Rev. 1142D-09/02................................... 182
Changes from Rev. 1142D-09/09 to Rev. 1142E-02/03 ................................... 182
Table of Contents .................................................................................. i
iii
1142E–AVR–02/03
iv
ATmega163(L)
1142E–AVR–02/03
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Atmel Operations
Corporate Headquarters
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© Atmel Corporation 2003.
Atmel Corporation makes no warranty for the use of its products, other than those expressly contained in the Company’s standard warranty
which is detailed in Atmel’s Terms and Conditions located on the Company’s web site. The Company assumes no responsibility for any errors
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Printed on recycled paper.
1142E–AVR–02/03
0M