ATMEL ATMEGA103L-4AC

Features
• Utilizes the AVR® RISC Architecture
• AVR – High-performance and Low-power RISC Architecture
•
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– 121 Powerful Instructions – Most Single Clock Cycle Execution
– 32 x 8 General Purpose Working Registers + Peripheral Control Registers
– Up to 6 MIPS Throughput at 6 MHz
Data and Nonvolatile Program Memory
– 128K Bytes of In-System Programmable Flash
Endurance: 1,000 Write/Erase Cycles
– 4K Bytes Internal SRAM
– 4K Bytes of In-System Programmable EEPROM
Endurance: 100,000 Write/Erase Cycles
– Programming Lock for Flash Program and EEPROM Data Security
– SPI Interface for In-System Programming
Peripheral Features
– On-chip Analog Comparator
– Programmable Watchdog Timer with On-chip Oscillator
– Programmable Serial UART
– Master/Slave SPI Serial Interface
– Real-time Counter (RTC) with Separate Oscillator
– Two 8-bit Timer/Counters with Separate Prescaler and PWM
– Expanded 16-bit Timer/Counter System with Separate Prescaler, Compare,
Capture Modes and Dual 8-, 9-, or 10-bit PWM
– Programmable Watchdog Timer with On-chip Oscillator
– 8-channel, 10-bit ADC
Special Microcontroller Features
– Low-power Idle, Power-save and Power-down Modes
– Software Selectable Clock Frequency
– External and Internal Interrupt Sources
Specifications
– Low-power, High-speed CMOS Process Technology
– Fully Static Operation
Power Consumption at 4 MHz, 3V, 25°C
– Active: 5.5 mA
– Idle Mode: 1.6 mA
– Power-down Mode: < 1 µA
I/O and Packages
– 32 Programmable I/O Lines, 8 Output Lines, 8 Input Lines
– 64-lead TQFP
Operating Voltages
– 2.7 - 3.6V for ATmega103L
– 4.0 - 5.5V for ATmega103
Speed Grades
– 0 - 4 MHz for ATmega103L
– 0 - 6 MHz for ATmega103
8-bit
Microcontroller
with 128K Bytes
In-System
Programmable
Flash
ATmega103
ATmega103L
Note:
Not recommended in new
designs.
Rev. 0945I–AVR–02/07
1
Pin Configuration
RD
WR
PC0 (A8)
PC2 (A10)
PC1 (A9)
PC3 (A11)
PC4 (A12)
PC6 (A14)
PC5 (A13)
PC7 (A15)
ALE
PA7 (AD7)
PA6 (AD6)
PA5 (AD5)
PA4 (AD4)
PA3 (AD3)
TQFP
48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33
(AD2) PA2 49
32 PD7 (T2)
(AD1) PA1 50
31 PD6 (T1)
(AD0) PA0 51
30 PD5
VCC 52
29 PD4 (IC1)
GND 53
28 PD3 (INT3)
(ADC7) PF7 54
27 PD2 (INT2)
(ADC6) PF6 55
26 PD1 (INT1)
(ADC5) PF5 56
25 PD0 (INT0)
(ADC4) PF4 57
24 XTAL1
(ADC3) PF3 58
23 XTAL2
(ADC2) PF2 59
22 GND
(ADC1) PF1 60
21 VCC
(ADC0) PF0 61
20 RESET
AREF 62
19 TOSC1
INDEX CORNER
AGND 63
18 TOSC2
AVCC 64
2
9
PEN
(PDO/TXD) PE1
(AC+) PE2
(AC-) PE3
(INT4) PE4
(INT5) PE5
(INT6) PE6
(INT7) PE7
10 11 12 13 14 15 16
(OC1B/PWM1B) PB6
8
(OC1A/PWM1A) PB5
7
(OC0/PWM0) PB4
6
(MISO) PB3
5
(MOSI) PB2
4
(SS) PB0
3
(SCK) PB1
2
(PDI/RXD) PE0
17 PB7 (OC2/PWM2)
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ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Description
The ATmega103(L) is a low-power, CMOS, 8-bit microcontroller based on the AVR
RISC architecture. By executing powerful instructions in a single clock cycle, the
ATmega103(L) achieves throughputs approaching 1 MIPS per MHz, allowing the system designer to optimize power consumption versus processing speed.
The AVR core is based on an enhanced RISC architecture that 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 cycle. The resulting architecture is more code efficient while achieving throughputs up to ten times faster than
conventional CISC microcontrollers.
The ATmega103(L) provides the following features: 128K bytes of In-System Programmable Flash, 4K bytes EEPROM, 4K bytes SRAM, 32 general purpose I/O lines, 8 input
lines, 8 output lines, 32 general purpose working registers, Real Time Counter (RTC), 4
flexible Timer/Counters with compare modes and PWM, UART, programmable Watchdog Timer with internal Oscillator, an SPI serial port and 3 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 Timer Oscillator continues
to run, allowing the user to maintain a timer base while the rest of the device is sleeping.
The device is manufactured using Atmel’s high-density nonvolatile memory technology.
The On-chip ISP Flash allows the Program memory to be reprogrammed In-System
through a serial interface or by a conventional nonvolatile memory programmer. By
combining an 8-bit RISC CPU with a large array of ISP Flash on a monolithic chip, the
Atmel ATmega103(L) is a powerful microcontroller that provides a highly flexible and
cost-effective solution to many embedded control applications.
The ATmega103(L) AVR is supported with a full suite of program and system development tools including: C compilers, macro assemblers, program debugger/simulators, InCircuit Emulators and evaluation kits.
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Block Diagram
Figure 1. The ATmega103(L) Block Diagram
PF0 - PF7
PA0 - PA7
PC0 - PC7
PORTA DRIVER/BUFFERS
PORTC DRIVERS
VCC
GND
PORTF BUFFERS
AVCC
ANALOG MUX
ADC
DATA REGISTER
PORTA
DATA REGISTER
PORTC
DATA DIR.
REG. PORTA
8-BIT DATA BUS
AGND
XTAL1
AREF
INTERNAL
OSCILLATOR
OSCILLATOR
XTAL1
PROGRAM
COUNTER
STACK
POINTER
WATCHDOG
TIMER
OSCILLATOR
PROGRAM
FLASH
SRAM
MCU CONTROL
REGISTER
TIMING AND
CONTROL
INSTRUCTION
REGISTER
INSTRUCTION
DECODER
+
-
ANALOG
COMPARATOR
CONTROL
LINES
DATA REGISTER
PORTE
DATA DIR.
REG. PORTE
TOSC2
TOSC1
RESET
ALE
TIMER/
COUNTERS
GENERAL
PURPOSE
REGISTERS
WR
RD
X
Y
Z
INTERRUPT
UNIT
ALU
EEPROM
STATUS
REGISTER
PROGRAMMING
LOGIC
SPI
UART
DATA REGISTER
PORTB
DATA DIR.
REG. PORTB
PEN
DATA REGISTER
PORTD
DATA DIR.
REG. PORTD
VCC
PORTE DRIVER/BUFFERS
PORTB DRIVER/BUFFERS
PORTD DRIVER/BUFFERS
GND
PE0 - PE7
4
PB0 - PB7
PD0 - PD7
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Pin Descriptions
VCC
Supply voltage.
GND
Ground.
Port A (PA7..PA0)
Port A is an 8-bit bi-directional I/O port. Port pins can provide internal pull-up resistors
(selected for each bit). The Port A output buffers can sink 20 mA 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 pull-up resistors are activated.
Port A serves as Multiplexed Address/Data bus when using external SRAM.
The Port A pins are tri-stated 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. 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.
The Port B pins are tri-stated when a reset condition becomes active, even if the clock is
not running.
Port C (PC7..PC0)
Port C is an 8-bit output port. The Port C output buffers can sink 20 mA.
Port C also serves as Address output when using external SRAM.
Since Port C is an output only port, the Port C pins are not tri-stated when a reset condition becomes active.
Port D (PD7..PD0)
Port D is an 8-bit bi-directional I/O port with internal pull-up resistors. 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.
The Port D pins are tri-stated when a reset condition becomes active, even if the clock is
not running.
Port E (PE7..PE0)
Port E is an 8-bit bi-directional I/O port with internal pull-up resistors. The Port E output
buffers can sink 20 mA. As inputs, Port E pins that are externally pulled low will source
current if the pull-up resistors are activated.
Port E also serves the functions of various special features.
The Port E pins are tri-stated when a reset condition becomes active, even if the clock is
not running
Port F (PF7..PF0)
Port F is an 8-bit input port. Port F also serves as the analog inputs for the ADC.
RESET
Reset input. An external reset is generated by a low level on the RESET pin. Reset
pulses longer than 50 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.
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TOSC1
Input to the inverting Timer/Counter Oscillator amplifier.
TOSC2
Output from the inverting Timer/Counter Oscillator amplifier.
WR
External SRAM write strobe
RD
External SRAM read strobe
ALE
ALE is the Address Latch Enable used when the External Memory is enabled. The ALE
strobe is used to latch the low-order address (8 bits) into an address latch during the first
access cycle, and the AD0 - 7 pins are used for data during the second access cycle.
AVCC
Supply voltage for Port F, including ADC. The pin must be connected to VCC when not
used for the ADC. See “ADC Noise Canceling Techniques” on page 82 for details when
using the ADC.
AREF
AREF is the analog reference input for the ADC converter. For ADC operations, a voltage in the range AGND to AVCC must be applied to this pin.
AGND
If the board has a separate analog ground plane, this pin should be connected to this
ground plane. Otherwise, connect to GND.
PEN
PEN is a programming enable pin for the Serial Programming mode. By holding this pin
low during a Power-on Reset, the device will enter the Serial Programming mode. PEN
has no function during normal operation.
Clock Options
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
MAX 1 HC BUFFER
HC
C2
C1
XTAL2
XTAL1
GND
Note:
6
When using the MCU Oscillator as a clock for an external device, an HC buffer should be
connected as indicated in the figure.
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
External Clock
To drive the device from an external clock source, XTAL2 should be left unconnected
while XTAL1 is driven as shown in Figure 3.
Figure 3. External Clock Drive Configuration
NC
XTAL2
EXTERNAL
OSCILLATOR
SIGNAL
XTAL1
GND
Timer Oscillator
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 TOSC1 is not
recommended.
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0945I–AVR–02/07
Architectural
Overview
Figure 4. The ATmega103(L) AVR RISC Architecture
AVR ATmega103(L) Architecture
Data Bus 8-bit
64K x 16
Program
Memory
Program
Counter
Status
and Test
32 x 8
General
Purpose
Registers
Instruction
Register
Direct Addressing
Control Lines
Indirect Addressing
Peripherals
Instruction
Decoder
ALU
4K x 8
Data
SRAM
4K x 8
EEPROM
The AVR uses a Harvard architecture concept – with separate memories and buses for
program and data. The Program memory is accessed with a single-level 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 Programmable Flash memory. With a few exceptions,
AVR instructions have a single 16-bit word format, meaning that every Program memory
address contains a single 16-bit instruction.
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 16-bit Stack Pointer (SP) is read/write accessible in the
I/O space.
The 4000 bytes data SRAM can be easily accessed through the five different addressing modes supported in the AVR architecture.
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 the different interrupts have a sep-
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ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
arate Interrupt Vector in the Interrupt Vector table at the beginning of the
Program memory. The different interrupts have priority in accordance with their Interrupt
Vector position. The lower the Interrupt Vector address, the higher the priority.
The memory spaces in the AVR architecture are all linear and regular memory maps.
General Purpose
Register File
Figure 5 shows the structure of the 32 general purpose working registers in the CPU.
Figure 5. 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 are 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 5, 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 4K bytes of SRAM available for general data are implemented as addresses $0060
to $0FFF.
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X-register, Y-register and Zregister
The registers R26..R31 have some added functions to their general purpose usage.
These registers are address pointers for indirect addressing of the SRAM. The three
indirect address registers X, Y, and Z are defined as:
Figure 6. X-, Y-, and Z-registers
15
X-register
0
7
0
7
0
R27 ($1B)
R26 ($1A)
15
Y-register
0
7
0
7
0
R29 ($1D)
R28 ($1C)
15
Z-register
0
7
0
7
0
R31 ($1F)
R30 ($1E)
In the different addressing modes these address registers have functions as fixed displacement, automatic increment and decrement (see the descriptions for the different
instructions).
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.
ISP Flash Program
Memory
The ATmega103(L) contains 128K bytes of On-chip In-System Programmable Flash
memory for program storage. Since all instructions are single or double 16-bit words, the
Flash is organized as 64K x 16. The Flash memory has an endurance of at least 1000
write/erase cycles.
Constant tables can be allocated in the entire Program memory space (see the LPM –
Load Program Memory and ELPM – Extended Load Program Memory instruction
descriptions).
SRAM Data Memory
The ATmega103(L) supports two different configurations for the SRAM Data memory as
listed in Table 1.
Table 1. Memory Configurations
Configuration
Internal SRAM Data Memory
External SRAM Data Memory
A
4000
None
B
4000
up to 64K
Note:
10
When using 64K of external SRAM, 60K will be available.
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 7. Memory Configurations
Memory Configuration A
Program Memory
Data Memory
$0000
32 Registers
64 I/O Registers
$0000 - $001F
$0020 - $005F
$0060
Internal SRAM
(4000 x 8)
$0FFF
Program Flash
(32K/64K x 16)
$7FFF/$FFFF
Memory Configuration B
Program Memory
Data Memory
$0000
32 Registers
64 I/O Registers
$0000 - $001F
$0020 - $005F
$0060
Internal SRAM
(4000 x 8)
$0FFF
$1000
Program Flash
(32K/64K x 16)
External SRAM
(0 - 64K x 8)
$7FFF/
$FFFF
$FFFF
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The 4096 first Data memory locations address both the Register File, the I/O memory
and the internal Data SRAM. The first 96 locations address the Register File and I/O
memory, and the next 4000 locations address the internal Data SRAM.
An optional external Data SRAM can be used with the ATmega103(L). This SRAM will
occupy an area in the remaining address locations in the 64K address space. This area
starts at the address following the internal SRAM. If a 64K external SRAM is used, 4K of
the external memory is lost as the addresses are occupied by internal memory.
When the addresses accessing the SRAM memory space exceeds the internal Data
memory locations, the external Data SRAM is accessed using the same instructions as
for the internal Data memory access. When the internal Data memories are accessed,
the read and write strobe pins (RD and WR) are inactive during the whole access cycle.
External SRAM operation is enabled by setting the SRE bit in the MCUCR Register.
Accessing external SRAM takes one additional clock cycle per byte compared to access
of the internal SRAM. This means that the commands LD, ST, LDS, STS, PUSH and
POP take one additional clock cycle. If the Stack is placed in external SRAM, interrupts,
subroutine calls and returns take two clock cycles extra because the 2-byte Program
Counter is pushed and popped. When external SRAM interface is used with wait state,
two additional clock cycles are used per byte. This has the following effect: Data transfer
instructions take two extra clock cycles, whereas interrupt, subroutine calls and returns
will need four clock cycles more than specified in the “Instruction Set Summary” on page
135.
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 Indirect with Displacement mode features 63 address locations reached 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 entire Data address space including the 32 general purpose working registers and
the 64 I/O Registers are all accessible through all these addressing modes. See the
next section for a detailed description of the different addressing modes.
Program and Data
Addressing Modes
12
The ATmega103(L) AVR 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.
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Register Direct, Single
Register Rd
Figure 8. Direct Single Register Addressing
REGISTER FILE
0
4
15
0
OP
d
d
31
The operand is contained in register d (Rd).
Register Direct, Two Registers
Rd and Rr
Figure 9. Direct Register Addressing, Two Registers
REGISTER FILE
0
15
9
5 4
OP
0
r
d
d
r
31
Operands are contained in registers r (Rr) and d (Rd). The result is stored in register d
(Rd).
I/O Direct
Figure 10. I/O Direct Addressing
I/O MEMORY
0
15
5
OP
n
0
P
63
Operand address is contained in six bits of the instruction word. n is the destination or
source register address.
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Data Direct
Figure 11. Direct Data Addressing
Data Space
20 19
31
OP
$0000
16
Rr/Rd
16 LSBs
15
0
$FFFF
A 16-bit Data address is contained in the 16 LSBs of a 2-word instruction. Rd/Rr specify
the destination or source register.
Data Indirect with
Displacement
Figure 12. Data Indirect with Displacement
Data Space
$0000
15
0
Y- OR Z-REGISTER
15
10
OP
6 5
n
0
a
$FFFF
Operand address is the result of the Y- or Z-register contents added to the address contained in six bits of the instruction word.
Data Indirect
Figure 13. Data Indirect Addressing
Data Space
$0000
15
0
X-, Y- OR Z-REGISTER
$FFFF
Operand address is the contents of the X-, Y,- or the Z-register.
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ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Data Indirect with Predecrement
Figure 14. Data Indirect Addressing with Pre-decrement
Data Space
$0000
15
0
X-, Y- OR Z-REGISTER
-1
$FFFF
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.
Data Indirect with Postincrement
Figure 15. Data Indirect Addressing with Post-increment
Data Space
$0000
15
0
X-, Y- OR Z-REGISTER
1
$FFFF
The X-, Y-, or the Z-register is incremented after the operation. Operand address is the
contents of the X-, Y-, or the Z-register prior to incrementing.
Constant Addressing Using
the LPM and ELPM
Instructions
Figure 16. Code Memory Constant Addressing
PROGRAM MEMORY
$0000
15
1 0
Z-REGISTER
$7FFF/$FFFF
Constant byte address is specified by the Z-register contents. The 15 MSBs select word
address (0 - 32K), LSB selects Low Byte if cleared (LSB = 0) or High Byte if set (LSB =
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0945I–AVR–02/07
1). If ELPM is used, LSB of the RAM Page Z register (RAMPZ) is used to select low or
high memory page (RAMPZ0 = 0: Low Page, RAMPZ0 = 1: High Page).
Direct Program Address, JMP
and CALL
Figure 17. Direct Program Memory Addressing
PROGRAM MEMORY
$0000
31
16
21 20
OP
16 LSBs
15
0
$7FFF/$FFFF
Program execution continues at the address immediate in the instruction words.
Indirect Program Addressing,
IJMP and ICALL
Figure 18. Indirect Program Memory Addressing
PROGRAM MEMORY
$0000
15
0
Z-REGISTER
$7FFF/$FFFF
Program execution continues at address contained by the Z-register (i.e., the PC is
loaded with the contents of the Z-register).
Relative Program Addressing,
RJMP and RCALL
Figure 19. Relative Program Memory Addressing
PROGRAM MEMORY
$0000
15
0
PC
1
12 11
15
OP
0
k
$7FFF/$FFFF
16
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Program execution continues at address PC + k + 1. The relative address k is -2048 to
2047.
EEPROM Data Memory
The EEPROM memory 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 57 specifying the EEPROM Address Register, the EEPROM Data Register and the EEPROM
Control Register.
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 external
clock crystal for the chip. No internal clock division is used.
Figure 20 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 20. 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 21 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.
Figure 21. Single Cycle ALU Operation
T1
T2
T3
T4
System Clock Ø
Total Execution Time
Register Operands Fetch
ALU Operation Execute
Result Write Back
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The internal Data SRAM access is performed in two System Clock cycles as described
in Figure 22.
Figure 22. On-chip Data SRAM Access Cycles
T1
T2
Prev. Address
Address
T3
T4
System Clock Ø
Address
Write
Data
WR
Read
Data
RD
See “Interface to External SRAM” on page 84. for a description of the access to the
external SRAM.
I/O Memory
18
The I/O space definition of the ATmega103(L) is shown in Table 2.
Table 2. ATmega103(L) I/O Space
I/O Address (SRAM
Address)
Name
Function
$3F ($5F)
SREG
Status REGister
$3E ($5E)
SPH
Stack Pointer High
$3D ($5D)
SPL
Stack Pointer Low
$3C ($5C)
XDIV
XTAL Divide Control Register
$3B ($5B)
RAMPZ
RAM Page Z Select Register
$3A ($5A)
EICR
External Interrupt Control Register
$39 ($59)
EIMSK
External Interrupt MaSK Register
$38 ($58)
EIFR
External Interrupt Flag Register
$37 ($57)
TIMSK
Timer/Counter Interrupt MaSK Register
$36 ($56)
TIFR
Timer/Counter Interrupt Flag Register
$35 ($55)
MCUCR
MCU General Control Register
$34 ($54)
MCUSR
MCU Status Register
$33 ($53)
TCCR0
Timer/Counter0 Control Register
$32 ($52)
TCNT0
Timer/Counter0 (8-bit)
$31 ($51)
OCR0
Timer/Counter0 Output Compare Register
$30 ($50)
ASSR
Asynchronous Mode Status Register
$2F ($4F)
TCCR1A
Timer/Counter1 Control Register A
$2E ($4E)
TCCR1B
Timer/Counter1 Control Register B
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Table 2. ATmega103(L) I/O Space (Continued)
I/O Address (SRAM
Address)
Name
Function
$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
Timer/Counter1 Input Capture Register High Byte
$26 ($46)
ICR1L
Timer/Counter1 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
$21 ($41)
WDTCR
Watchdog Timer Control Register
$1F ($3F)
EEARH
EEPROM Address Register High
$1E ($3E)
EEARL
EERPOM Address Register Low
$1D ($3D)
EEDR
EEPROM Data Register
$1C ($3C)
EECR
EEPROM Control Register
$1B ($3B)
PORTA
Data Register, Port A
$1A ($3A)
DDRA
Data Direction Register, Port A
$19 ($39)
PINA
Input Pins, Port A
$18 ($38)
PORTB
Data Register, Port B
$17 ($37)
DDRB
Data Direction Register, Port B
$16 ($36)
PINB
Input Pins, Port B
$15 ($35)
PORTC
Data Register, Port C
$12 ($32)
PORTD
Data Register, Port D
$11 ($31)
DDRD
Data Direction Register, Port D
$10 ($30)
PIND
Input Pins, Port D
$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)
USR
UART Status Register
$0A ($2A)
UCR
UART Control Register
$09 ($29)
UBRR
UART Baud Rate Register
$08 ($28)
ACSR
Analog Comparator Control and Status Register
$07 ($27)
ADMUX
ADC Multiplexer Select Register
19
0945I–AVR–02/07
Table 2. ATmega103(L) I/O Space (Continued)
I/O Address (SRAM
Address)
Note:
Name
Function
$06 ($26)
ADCSR
ADC Control and Status Register
$05 ($25)
ADCH
ADC Data Register High
$04 ($24)
ADCL
ADC Data Register Low
$03 ($23)
PORTE
Data Register, Port E
$02 ($22)
DDRE
Data Direction Register, Port E
$01 ($21)
PINE
Input Pins, Port E
$00 ($20)
PINF
Input Pins, Port F
Reserved and unused locations are not shown in the table.
All the different ATmega103(L) I/Os and peripherals are placed in the I/O space. The different I/O locations are directly 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 Summary” on page 135 for
more details. When using the I/O specific instructions IN and OUT, the I/O Register
address $00 - $3F are used. When addressing I/O Registers as SRAM, $20 must be
added to this address. 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 “1” 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 different I/O and peripherals control registers are explained in the following
sections.
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 separate control registers. If the
Global Interrupt Enable Register is cleared (zero), none of the interrupts are enabled
independent of the individual interrupt enable settings. 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 cop-
20
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
ied 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 on page 135 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 on page 135 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 on page 135 for detailed information.
• Bit 2 – N: Negative Flag
The Negative Flag N indicates a negative result from an arithmetical or logical operation.
See the Instruction set description on page 135 for detailed information.
• Bit 1 – Z: Zero Flag
The Zero Flag Z indicates a zero result from an arithmetical or logical operation. See the
instruction set description on page 135 for detailed information.
• Bit 0 – C: Carry Flag
The Carry Flag C indicates a carry in an arithmetical or logical operation. See the
instruction set description on page 135 for detailed information.
Note that the Status Register is not automatically stored when entering an interrupt routine or restored when returning from an interrupt routine. This must be handled by
software.
Stack Pointer – SP
The general AVR 16-bit Stack Pointer is effectively built up of two 8-bit registers in the
I/O space locations $3E ($5E) and $3D ($5D). As the ATmega103(L) supports up to
64K bytes memory, all 16 bits are used.
Bit
15
14
13
12
11
10
9
8
$3E ($5E)
SP15
SP14
SP13
SP12
SP11
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
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
Initial Value
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 2
when an address is pushed onto the Stack with subroutine calls and interrupts. The
Stack Pointer is incremented by 1 when data is popped from the Stack with the POP
21
0945I–AVR–02/07
instruction and it is incremented by 2 when an address is popped from the Stack with
return from subroutine RET or return from interrupt RETI.
RAM Page Z Select Register –
RAMPZ
Bit
7
6
5
4
3
2
1
0
$3B ($5B)
–
–
–
–
–
–
–
RAMPZ0
Read/Write
R
R
R
R
R
R
R
R/W
Initial Value
0
0
0
0
0
0
0
0
RAMPZ
The RAMPZ Register is normally used to select which 64K RAM page is accessed by
the Z pointer. As the ATmega103(L) does not support more than 64K of SRAM memory,
this register is used only to select which page in the Program memory is accessed when
the ELPM instruction is used. The different settings of the RAMPZ0 bit have the following effects:
RAMPZ0 = 0:
Program memory address $0000 - $7FFF (lower 64K bytes) is
accessed by ELPM
RAMPZ0 = 1:
Program memory address $8000 - $FFFF (higher 64K bytes) is
accessed by ELPM
Note that LPM is not affected by the RAMPZ setting.
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)
SRE
SRW
SE
SM1
SM0
–
–
–
Read/Write
R/W
R/W
R/W
R/W
R/W
R
R
R
Initial Value
0
0
0
0
0
0
0
0
MCUCR
• Bit 7 – SRE: External SRAM Enable
When the SRE bit is set (one), the external Data SRAM is enabled, and the pin functions
AD0 - 7 (Port A), and A8 - 15 (Port C) are activated as the alternate pin functions. Then
the SRE bit overrides any pin direction settings in the respective Data Direction Registers. When the SRE bit is cleared (zero), the external Data SRAM is disabled and the
normal pin and data direction settings are used.
• Bit 6 – SRW: External SRAM Wait State
When the SRW bit is set (one), a one-cycle wait state is inserted in the external Data
SRAM access cycle. When the SRW bit is cleared (zero), the external Data SRAM
access is executed with a three-cycle scheme. See Figure 51 on page 85 and Figure 52
on page 85.
• Bit 5 – 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 programmer’s purpose, it is recommended to set the Sleep Enable (SE) bit just before the
execution of the SLEEP instruction.
22
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
• Bits 4, 3 – SM1/SM0: Sleep Mode Select Bits 1 and 0
This bit selects between the three available sleep modes as shown in Table 3.
Table 3. Sleep Mode Select
SM1
SM0
Sleep Mode
0
0
Idle mode
0
1
Reserved
1
0
Power-down
1
1
Power-save
• Bits 2..0 – Res: Reserved Bits
These bits are reserved bits in the ATmega103(L) and always read as zero.
XTAL Divide Control Register
– XDIV
The XTAL Divide Control Register is used to divide the XTAL clock frequency by a number in the range 1 - 129. This feature can be used to decrease power consumption when
the requirement for processing power is low.
Bit
7
6
5
4
3
2
1
0
$3C ($5C)
XDIVEN
XDIV6
XDIV5
XDIV4
XDIV3
XDIV2
XDIV1
XDIV0
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
XDIV
• Bit 7 – XDIVEN: XTAL Divide Enable
When the XDIVEN bit is set (one), the clock frequency of the CPU and all peripherals is
divided by the factor defined by the setting of XDIV6 - XDIV0. This bit can be set and
cleared run-time to vary the clock frequency as suitable to the application.
• Bits 6..0 – XDIV6..XDIV0: XTAL Divide Select Bits 6 - 0
These bits define the division factor that applies when the XDIVEN bit is set (one). If the
value of these bits is denoted d, the following formula defines the resulting CPU clock
frequency fclk:
XTAL
f CLK = ------------------129 – d
The value of these bits can only be changed when XDIVEN is zero. When XDIVEN is
set to one, the value written simultaneously into XDIV6..XDIV0 is taken as the division
factor. When XDIVEN is cleared to zero, the value written simultaneously into
XDIV6..XDIV0 is rejected. As the divider divides the Master Clock Input to the MCU, the
speed of all peripherals is reduced when a division factor is used.
Reset and Interrupt
Handling
The ATmega103(L) provides 23 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 that 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 4. The list
also determines the priority levels of the different interrupts. The lower the address, the
23
0945I–AVR–02/07
higher the priority level. RESET has the highest priority and next is INT0 (the External
Interrupt Request 0), etc.
Table 4. Reset and Interrupt Vectors
Vector No.
Program
Address
Source
Interrupt Definition
1
$0000
RESET
Hardware Pin, Power-on Reset and Watchdog
Reset
2
$0002
INT0
External Interrupt Request 0
3
$0004
INT1
External Interrupt Request 1
4
$0006
INT2
External Interrupt Request 2
5
$0008
INT3
External Interrupt Request 3
6
$000A
INT4
External Interrupt Request 4
7
$000C
INT5
External Interrupt Request 5
8
$000E
INT6
External Interrupt Request 6
9
$0010
INT7
External Interrupt Request 7
10
$0012
TIMER2 COMP
Timer/Counter2 Compare Match
11
$0014
TIMER2 OVF
Timer/Counter2 Overflow
12
$0016
TIMER1 CAPT
Timer/Counter1 Capture Event
13
$0018
TIMER1 COMPA
Timer/Counter1 Compare Match A
14
$001A
TIMER1 COMPB
Timer/Counter1 Compare Match B
15
$001C
TIMER1 OVF
Timer/Counter1 Overflow
16
$001E
TIMER0 COMP
Timer/Counter0 Compare Match
17
$0020
TIMER0 OVF
Timer/Counter0 Overflow
18
$0022
SPI, STC
SPI Serial Transfer Complete
19
$0024
UART, RX
UART, Rx Complete
20
$0026
UART, UDRE
UART Data Register Empty
21
$0028
UART, TX
UART, Tx Complete
22
$002A
ADC
ADC Conversion Complete
23
$002C
EE READY
EEPROM Ready
24
$002E
ANALOG COMP
Analog Comparator
The most typical program setup for the Reset and Interrupt vector addresses are:
Address Labels Code
24
Comments
$0000
jmp
RESET
; Reset Handler
$0002
jmp
EXT_INT0
; IRQ0 Handler
$0004
jmp
EXT_INT1
; IRQ1 Handler
$0006
jmp
EXT_INT2
; IRQ2 Handler
$0008
jmp
EXT_INT3
; IRQ3 Handler
$000A
jmp
EXT_INT4
; IRQ4 Handler
$000C
jmp
EXT_INT5
; IRQ5 Handler
$000E
jmp
EXT_INT6
; IRQ6 Handler
$0010
jmp
EXT_INT7
; IRQ7 Handler
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
$0012
jmp
TIM2_COMP
; Timer2 Compare Handler
$0014
jmp
TIM2_OVF
; Timer2 Overflow Handler
$0016
jmp
TIM1_CAPT
; Timer1 Capture Handler
$0018
jmp
TIM1_COMPA
; Timer1 Compare A Handler
$001A
jmp
TIM1_COMPB
; Timer1 Compare B Handler
$001C
jmp
TIM1_OVF
; Timer1 Overflow Handler
$001E
jmp
TIM0_COMP
; Timer0 Compare Handler
$0020
jmp
TIM0_OVF
; Timer0 Overflow Handler
$0022
jmp
SPI_STC
; SPI Transfer Complete Handler
$0024
jmp
UART_RXC
; UART RX Complete Handler
$0026
jmp
UART_DRE
; UDR Empty Handler
$0028
jmp
UART_TXC
; UART TX Complete Handler
$002A
jmp
ADC
; ADC Conversion Complete Handler
$002C
jmp
EE_RDY
; EEPROM Ready Handler
$002E
jmp
ANA_COMP
; Analog Comparator Handler
;
$0030
ldi
r16, high(RAMEND); Main program start
$0031
out
SPH,r16
$0032
ldi
r16, low(RAMEND)
$0033
out
SPL,r16
$0034
<instr>
...
Reset Sources
MAIN:
...
...
xxx
...
The ATmega103(L) has three 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 50 ns.
•
Watchdog Reset. The MCU is reset when the Watchdog Timer period expires and
the Watchdog is enabled.
During reset, all I/O Registers except the MCU Status Register are then set to their initial
values and the program starts execution from address $0000. The instruction placed in
address $0000 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 23
shows the reset logic. Table 5 defines the timing and electrical parameters of the reset
circuitry.
25
0945I–AVR–02/07
Figure 23. Reset Logic
D
Q
Watchdog
Timer
E
On-chip
RC Oscillator
XTAL1
26
14-stage Ripple Counter
Q8
Q11 Q13
S
Q
R
Q
SUT0
SUT1
PEN
Reset Circuit
COUNTER RESET
100-500K
10-50K
RESET
POR
INTERNAL
RESET
Power-on Reset
Circuit
VCC
Delay Unit
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Table 5. Reset Characteristics (VCC = 5.0V)
Symbol
VPOT(1)
Parameter
Condition
Min
Typ
Max
Units
Power-on Reset Threshold
(rising)
1.0
1.4
1.8
V
Power-on Reset Threshold
(falling)
0.4
0.6
0.8
V
RESET Pin Threshold Voltage
VRST
SUT = 00
TTOUT
Note:
Power-on Reset
Reset Delay Time-out Period
SUT = 01
SUT = 10
SUT = 11
0.4
3.2
12.8
VCC/2
V
5
CPU cycles
0.5
4.0
16.0
0.6
4.8
19.2
ms
1. The Power-on Reset will not work unless the supply voltage has been below VPOT
(falling).
A Power-on Reset (POR) circuit ensures that the device is Reset from Power-on. As
shown in Figure 23, an internal timer clocked from the Watchdog Timer Oscillator prevents the MCU from starting until after a certain period after VCC has reached the Poweron Threshold voltage (VPOT), regardless of the VCC rise time (see Figure 24). The Fuse
bits SUT1 and SUT0 are used to select start-up time as indicated in Table 5. A “0” in the
table indicates that the fuse is programmed.
The user can select the start-up time according to typical Oscillator start-up time. The
number of WDT Oscillator cycles used for each Time-out except for SUT = 00 is shown
in Table 6. The frequency of the Watchdog Oscillator is voltage-dependent as shown in
“Typical Characteristics” on page 123.
Table 6. Number of Watchdog Oscillator Cycles
SUT 1/0
Time-out at VCC = 5V
Number of WDT Cycles
01
0.5 ms
512
10
4.0 ms
4K
11
16.0 ms
16K
The setting SUT 1/0 = 00 starts the MCU after 5 CPU clock cycles, and can be used
when an external clock signal is applied to the XTAL1 pin. This setting does not use the
WDT Oscillator and enables very fast start-up from the sleep modes Power-down or
Power-save if the clock signal is present during sleep. For details, refer to the programming specification starting on page 104.
If the built-in start-up delay is sufficient, RESET can be connected to VCC directly or via
an external pull-up resistor. By holding the pin low for a period after V CC has been
applied, the Power-on Reset period can be extended. Refer to Figure 25 for a timing
example of this.
27
0945I–AVR–02/07
Figure 24. MCU Start-up, RESET Tied to VCC.
VCC
RESET
VPOT
VRST
tTOUT
TIME-OUT
INTERNAL
RESET
Figure 25. MCU Start-up, RESET Controlled Externally
VCC
VPOT
VRST
RESET
tTOUT
TIME-OUT
INTERNAL
RESET
External Reset
An external reset is generated by a low level on the RESET pin. Reset pulses longer
than 50 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 26. External Reset during Operation
VCC
RESET
VRST
TIME-OUT
tTOUT
INTERNAL
RESET
28
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
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 55 for details on operation of the Watchdog.
Figure 27. Watchdog Reset during Operation
VCC
RESET
1 XTAL Cycle
WDT
TIME-OUT
tTOUT
RESET
TIME-OUT
INTERNAL
RESET
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)
–
–
–
–
–
–
EXTRF
PORF
Read/Write
R
R
R
R
R
R
R/W
R/W
Initial Value
0
0
0
0
0
0
See bit description
MCUSR
• Bits 7..2 – Res: Reserved Bits
These bits are reserved bits in the ATmega103(L) and always read as zero.
• Bit 1 – EXTRF: External Reset Flag
After a Power-on Reset, this bit is undefined (X). It will be set by an external reset. A
Watchdog reset will leave this bit unchanged.
• Bit 0 – PORF: Power-on Reset Flag
This bit is set by a Power-on Reset. A Watchdog Reset or an External Reset will leave
this bit unchanged.
To summarize, Table 7 shows the value of these two bits after the three modes of reset:
Table 7. PORF and EXTRF Values after Reset
Reset Source
EXTRF
PORF
Power-on Reset
undefined
1
External Reset
1
unchanged
unchanged
unchanged
Watchdog Reset
To make use of these bits to identify a reset condition, the user software should clear
both the PORF and EXTRF bits as early as possible in the program. Checking the
PORF and EXTRF values is done before the bits are cleared. If the bit is cleared before
29
0945I–AVR–02/07
an external or Watchdog reset occurs, the source of reset can be found by using the following truth table, Table 8.
Table 8. Reset Source Identification
Reset Source
Interrupt Handling
EXTRF
PORF
Watchdog Reset
0
0
Power-on Reset
0
1
External Reset
1
0
Power-on Reset
1
1
The ATmega103(L) has two dedicated 8-bit Interrupt Mask Control Registers; EIMSK
(External Interrupt Mask Register) and TIMSK (Timer/Counter Interrupt Mask Register).
In addition, other enable and mask bits can be found in the peripheral control registers.
When an interrupt occurs, the Global Interrupt Enable I-bit is cleared (zero) and all interrupts are disabled. The user software can 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 logical “1” 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.
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 active.
Note that the Status Register is not automatically stored when entering an interrupt routine or restored when returning from an interrupt routine. This must be handled by
software.
External Interrupt Mask
Register – EIMSK
Bit
7
6
5
4
3
2
1
0
$39 ($59)
INT7
INT6
INT5
INT4
INT3
INT2
INT1
INT0
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
EIMSK
• Bits 7..4 – INT7 - INT4: External Interrupt Request 7 - 4 Enable
When an INT7 - INT4 bit is set (one) and the I-bit in the Status Register (SREG) is set
(one), the corresponding external pin interrupt is enabled. The Interrupt Sense Control
bits in the External Interrupt Control Register (EICR) define whether the external interrupt is activated on rising or falling edge or is level-sensed. Activity on any of these pins
will trigger an interrupt request even if the pin is enabled as an output. This provides a
way of generating a software interrupt.
30
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
• Bits 3..0 – INT3 - INT0: External Interrupt Request 3 - 0 Enable
When an INT3 - INT0 bit is set (one) and the I-bit in the Status Register (SREG) is set
(one), the corresponding external pin interrupt is enabled. The external interrupts are
always low-level triggered interrupts. Activity on any of these pins will trigger an interrupt
request even if the pin is enabled as an output. This provides a way of generating a software interrupt. When enabled, a level-triggered interrupt will generate an interrupt
request as long as the pin is held low.
External Interrupt Flag
Register – EIFR
Bit
7
6
5
4
3
2
1
0
INTF7
INTF6
INTF5
INTF4
–
–
–
–
Read/Write
R/W
R/W
R/W
R/W
R
R
R
R
Initial Value
0
0
0
0
0
0
0
0
$38 ($58)
EIFR
• Bits 7..4 – INTF7 - INTF4: External Interrupt 7 - 4 Flags
When an edge on the INT7 - INT4 pins triggers an interrupt request, the corresponding
Interrupt Flag, INTF7 - INTF4, becomes set (one). If the I-bit in SREG and the corresponding interrupt enable bit, INT7 - INT4 in EIMSK, is set (one), the MCU will jump to
the Interrupt Vector. The flag is cleared when the corresponding interrupt routine is executed. Alternatively, the flag is cleared by writing a logical “1” to it. These flags are
always cleared when INTF7 - INFT4 are configured as level interrupts.
• Bits 3..0 – Res: Reserved Bits
These bits are reserved bits in the ATmega103(L) and always read as zero.
External Interrupt Control
Register – EICR
Bit
7
6
5
4
3
2
1
0
$3A ($5A)
ISC71
ISC70
ISC61
ISC60
ISC51
ISC50
ISC41
ISC40
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
EICR
• Bits 7..0 – ISCX1, ISCX0: External Interrupt 7 - 4 Sense Control Bits
The External Interrupts 7 - 4 are activated by the external pins INT7 - INT4 if the SREG
I-flag and the corresponding interrupt mask in the EIMSK are set. The level and edges
on the external pins that activate the interrupts are defined in Table 9.
Table 9. Interrupt Sense Control
ISCX1
ISCX0
Description
0
0
The low level of INTX generates an interrupt request.
0
1
Reserved
1
0
The falling edge of INTX generates an interrupt request.
1
1
The rising edge of INTX generates an interrupt request.
The value on the INTX pin is sampled before detecting edges. If edge interrupt is
selected, pulses that last longer than one CPU clock period will generate an interrupt.
Shorter pulses are not guaranteed to generate an interrupt. Observe that CPU clock frequency can be lower than the XTAL frequency if the XTAL divider is enabled. If low-level
interrupt is selected, the low level must be held until the completion of the currently exe-
31
0945I–AVR–02/07
cuting instruction to generate an interrupt. If enabled, a level-triggered interrupt will
generate an interrupt request as long as the pin is held low.
32
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Timer/Counter Interrupt Mask
Register – TIMSK
Bit
7
6
5
4
3
2
1
0
OCIE2
TOIE2
TICIE1
OCIE1A
OCIE1B
TOIE1
OCIE0
TOIE0
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
$37 ($57)
TIMSK
• Bit 7 – OCIE2: Timer/Counter2 Output Compare 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 $0012) 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
$0014) 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
(at vector $0016) is executed if a capture-triggering event occurs on pin 29, PD4(IC1),
i.e., when the ICF1 bit is set in the Timer/Counter Interrupt Flag Register.
• Bit 4 – OCE1A: Timer/Counter1 Output Compare A 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 $0018) 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.
• Bit 3 – OCIE1B: Timer/Counter1 Output Compare B 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 $001A) 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.
• 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
$001C) is executed if an overflow in Timer/Counter1 occurs, i.e., when the TOV1 bit is
set in the Timer/Counter Interrupt Flag Register.
• Bit 1 – OCIE0: Timer/Counter0 Output Compare Interrupt Enable
When the OCIE0 bit is set (one) and the I-bit in the Status Register is set (one), the
Timer/Counter0 Compare Match interrupt is enabled. The corresponding interrupt (at
vector $001E) is executed if a compare match in Timer/Counter0 occurs, i.e., when the
OCF0 bit is set in the Timer/Counter Interrupt Flag Register.
33
0945I–AVR–02/07
• 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
$0020) is executed if an overflow in Timer/Counter0 occurs, i.e., when the TOV0 bit is
set in the Timer/Counter Interrupt Flag Register.
34
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Timer/Counter Interrupt Flag
Register – TIFR
Bit
7
6
5
4
3
2
1
0
OCF2
TOV2
ICF1
OCF1A
OCF1B
TOV1
OCF0
TOV0
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
$36 ($56)
TIFR
• Bit 7 – OCF2: Output Compare Flag 2:
The OCF2 bit is set (one) when compare match occurs between Timer/Counter2 and
the data in OCR2 – Output Compare Register 2. OCF2 is cleared by hardware when
executing the corresponding interrupt handling vector. Alternatively, OCF2 is cleared by
writing a logical “1” to the flag. When the I-bit in SREG, and OCIE2 (Timer/Counter2
Compare Interrupt Enable) and the OCF2 are set (one), the Timer/Counter2 Output
Compare 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 logical “1” to the flag. When the I-bit in SREG, and TOIE2
(Tim er/Co un ter1 Ove rflow Inte rrup t En able) an d TO V2 a re set (o ne) , th e
Timer/Counter2 Overflow interrupt is executed. In PWM mode, this bit is set when
Timer/Counter2 advances from $00.
• Bit 5 – ICF1: Input Capture Flag 1
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 logical “1” to the flag. When the SREG I-bit,
TICIE1 (Timer/Counter1 Input Capture Interrupt Enable) and ICF1 are set (one), the
Timer/Counter1 Capture interrupt is executed.
• Bit 4 – OCF1A: Output Compare Flag 1A
The OCF1A bit is set (one) when 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 logical “1” to the flag. When the I-bit in SREG and OCIE1A
(Timer/Counter1 Compare Interrupt Enable) and the OCF1A are set (one), the
Timer/Counter1 Compare A Match interrupt is executed.
• Bit 3 – OCF1B: Output Compare Flag 1B
The OCF1B bit is set (one) when 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 logical “1” to the flag. When the I-bit in SREG and OCIE1B
(Timer/Counter1 Compare Match Interrupt Enable) and the OCF1B are set (one), the
Timer/Counter1 Compare B 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 logical “1” to the flag. When the I-bit in SREG and TOIE1
35
0945I–AVR–02/07
(Tim er/Co un ter1 Ove rflow Inte rrup t En able) an d TO V1 a re set (o ne) , th e
Timer/Counter1 Overflow interrupt is executed. In PWM mode, this bit is set when
Timer/Counter1 advances from $0000.
• Bit 1 – OCF0: Output Compare Flag 0
The OCF0 bit is set (one) when compare match occurs between Timer/Counter0 and
the data in OCR0 – Output Compare Register 0. OCF0 is cleared by hardware when
executing the corresponding interrupt handling vector. Alternatively, OCF0 is cleared by
writing a logical “1” to the flag. When the I-bit in SREG and OCIE0 (Timer/Counter2
Compare Interrupt Enable) and the OCF0 are set (one), the Timer/Counter0 Output
Compare interrupt is executed.
• 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 logical “1” to the flag. When the SREG I-bit and TOIE0
(Tim er/Co un ter0 Ove rflow Inte rrup t En able) an d TO V0 a re set (o ne) , th e
Timer/Counter0 Overflow interrupt is executed. In PWM mode, this bit is set when
Timer/Counter0 advances from $00.
Interrupt Response Time
The interrupt execution response for all the enabled AVR interrupts is four clock cycles
minimum. Four clock cycles after the Interrupt Flag has been set, the Program Vector
address for the actual interrupt handling routine is executed. During this four-clock-cycle
period, the Program Counter (2 bytes) is pushed onto the Stack, and the Stack Pointer
is decremented by 2. 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 multi-cycle
instruction, this instruction is completed before the interrupt is served.
A return from an interrupt handling routine (same as for a subroutine call routine) takes
four clock cycles. During these four clock cycles, the Program Counter (2 bytes) is
popped back from the Stack, and the Stack Pointer is incremented by 2. When the AVR
exits from an interrupt, it will always return to the main program and execute one more
instruction before any pending interrupt is served.
Sleep Modes
To enter any of the three 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, Power-down, or Power-save) will be activated by the
SLEEP instruction, see Table 3 on page 23.
If an enabled interrupt occurs while the MCU is in a sleep mode, the MCU awakes, 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. If a reset
occurs during sleep mode, the MCU wakes up and executes from the Reset Vector.
Idle Mode
36
When the SM1/SM0 bits are set to 00, the SLEEP instruction makes the MCU enter the
Idle mode, stopping the CPU but allowing SPI, UART, Analog Comparator, ADC,
Timer/Counters, Watchdog and the interrupt system to continue operating. 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. When the MCU wakes up from Idle mode,
the CPU starts program execution immediately.
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Power-down Mode
When the SM1/SM0 bits are set to 10, the SLEEP instruction makes the MCU enter the
Power-down mode. In this mode, the external Oscillator is stopped while the external
interrupts and the Watchdog (if enabled) continue operating. Only an External Reset, a
Watchdog Reset (if enabled), 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 “Typical Characteristics” on
page 123.
When waking up from Power-down mode, 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 SUT fuses that
define the Reset Time-out period. The wake-up period is equal to the clock reset period,
as shown in Table 5 on page 27.
If the wake-up condition disappears before the MCU wakes up and starts to execute,
e.g., a low-level on is not held long enough, the interrupt causing the wake-up will not be
executed.
Power-save Mode
When the SM1/SM0 bits are 11, the SLEEP instruction makes the MCU enter the
Power-save mode. This mode is identical to Power-down, with one exception:
If Timer/Counter0 is clocked asynchronously, i.e., the AS0 bit in ASSR is set,
Timer/Counter0 will run during sleep. In addition to the Power-down wake-up sources,
the device can also wake up from either Timer Overflow or Output Compare event from
Timer/Counter0 if the corresponding Timer/Counter0 interrupt enable bits are set in
TIMSK. To ensure that the part executes the interrupt routine when waking up, also set
the Global Interrupt Enable bit i SREG.
When waking up from Power-save mode by an external interrupt, two instruction cycles
are executed before the Interrupt Flags are updated. When waking up by the asynchronous timer, three instruction cycles are executed before the flags are updated. During
these cycles, the processor executes instructions, but the interrupt condition is not readable and the interrupt routine has not started yet. 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 AS0 is 0.
37
0945I–AVR–02/07
Timer/Counters
The ATmega103(L) provides three general purpose Timer/Counters – two 8-bit T/Cs
and one 16-bit T/C. Timer/Counter0 optionally can be asynchronously clocked from an
external Oscillator. This Oscillator is optimized for use with a 32.768 kHz crystal,
enabling use of Timer/Counter0 as a Real Time Clock (RTC). Timer/Counter0 has its
own prescaler. Timer/Counters 1 and 2 have individual prescaling selection from the
same 10-bit prescaling timer. 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 that triggers
the counting.
Timer/Counter
Prescalers
Figure 28. Prescaler for Timer/Counter1 and Timer/Counter2
CK
CK/1024
CK/8
CK/64
CK/256
10-BIT T/C PRESCALER
T1
T2
0
0
CS20
CS21
CS22
CS10
CS11
CS12
TIMER/COUNTER2 CLOCK SOURCE
TCK2
For Timer/Counters 1 and 2, the
CK/256 and CK/1024, where CK
can be lower than the XTAL
Timer/Counters 1 and 2, added
selected as clock sources.
TIMER/COUNTER1 CLOCK SOURCE
TCK1
four different prescaled selections are: CK/8, CK/64,
is the CPU clock. Observe that CPU clock frequency
frequency if the XTAL divider is enabled. For
selections as CK, external source and stop can be
Figure 29. The Timer/Counter0 Prescaler
CK
PCK0
PCK0/1024
PCK0/256
PCK0/128
PCK0/64
PCK0/32
AS0
PCK0/8
10-BIT T/C PRESCALER
TOSC1
CS00
CS01
CS02
TIMER/COUNTER0 CLOCK SOURCE
PCK0
38
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
The clock source for Timer/Counter0 prescaler is named PCK0. PCK0 is by default connected to the main system clock CK. Observe that CPU clock frequency can be lower
than the XTAL frequency if the XTAL divider is enabled. By setting the AS0 bit in ASSR,
Timer/Counter0 prescaler is asynchronously clocked from the TOSC1 pin. This enables
use of Timer/Counter0 as a Real Time Clock (RTC). A crystal can be connected
between the TOSC1 and TOSC2 pins to serve as an independent clock source for
Timer/Counter0. This Oscillator is optimized for use with a 32.768 kHz crystal.
8-bit Timer/Counters
T/C0 and T/C2
Figure 30 shows the block diagram for Timer/Counter0. Figure 31 shows the block diagram for Timer/Counter2.
Figure 30. Timer/Counter0 Block Diagram
T/C0 OVER- T/C0 COMPARE
FLOW IRQ
MATCH IRQ
8-BIT DATA BUS
7
CS00
CS02
CS01
CTC0
COM00
PWM0
T/C0 CONTROL
REGISTER (TCCR0)
COM01
TOV0
OCF0
TOV1
OCF0
OCF2A
ICF1
OCF2B
OCF2
0
TIMER/COUNTER0
(TCNT0)
TOV2
TIMER INT. FLAG
REGISTER (TIFR)
TIMER INT. MASK
REGISTER (TIMSK)
7
TOV0
TOIE0
TOIE1
OCIE0
OCIE1B
OCIE1A
TICIE1
OCIE2
TOIE2
8-BIT ASYNCH T/C0 DATA BUS
T/C CLEAR
T/C CLK SOURCE
UP/DOWN
CONTROL
LOGIC
PCK0
0
8-BIT COMPARATOR
0
OUTPUT COMPARE
REGISTER0 (OCR0)
CK
TCK0
ICR0UB
OCR0UB
AS0
ASYNCH. STATUS
REGISTER (ASSR)
TC0UB
7
SYNCH UNIT
39
0945I–AVR–02/07
Figure 31. Timer/Counter2 Block Diagram
CS20
CS22
CS21
CTC2
COM20
T/C2 CONTROL
REGISTER (TCCR2)
PWM2
TOV0
TOV1
OCF0
ICF1
OCF2A
0
TIMER/COUNTER2
(TCNT2)
OCF2B
7
TOV2
OCF2
TIMER INT. FLAG
REGISTER (TIFR)
COM21
OCF2
TIMER INT. MASK
REGISTER (TIMSK)
TOV2
TOIE0
OCIE0
OCIE1A
TOIE1
OCIE1B
TICIE1
TOIE2
OCIE2
8-BIT DATA BUS
T/C2 OVER- T/C2 COMPARE
FLOW IRQ
MATCH IRQ
T/C CLEAR
T/C CLK SOURCE
UP/DOWN
CK
CONTROL
LOGIC
T2
7
0
8-BIT COMPARATOR
7
0
OUTPUT COMPARE
REGISTER2 (OCR2)
The 8-bit Timer/Counter0 can select clock source from PCK0 or prescaled PCK0. The 8bit Timer/Counter2 can select clock source from CK, prescaled CK or an external pin.
Both Timer/Counters can be stopped as described in the specification for the
Timer/Counter Control Registers – TCCR0 and TCCR2.
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/Counter Control Registers – TCCR0 and TCCR2. The interrupt enable/disable
settings are found in the Timer/Counter Interrupt Mask Register (TIMSK).
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
clock period. The external clock signal is sampled on the rising edge of the internal CPU
clock.
The 8-bit Timer/Counters feature a high-resolution and a high-accuracy usage with the
lower prescaling opportunities. Similarly, the high prescaling opportunities make these
units useful for lower speed functions or exact timing functions with infrequent actions.
Both Timer/Counters support two Output Compare functions using the Output Compare
Registers (OCR0 and OCR2) as the data source to be compared to the Timer/Counter
contents. The Output Compare functions include optional clearing of the counter on
compare match and action on the Output Compare pins – PB4(OC0/PWM0) and
PB7(OC2/PWM2) – on compare match.
Timer/Counters 0 and 2 can also be used as 8-bit Pulse Width Modulators. In this mode
the Timer/Counter and the Output Compare Register serve as a glitch-free, stand-alone
PWM with centered pulses. Refer to page 43 for a detailed description of this function.
40
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Timer/Counter0 Control
Register – TCCR0
Timer/Counter2 Control
Register – TCCR2
Bit
7
6
5
4
3
2
1
0
33 ($53)
–
PWM0
COM01
COM00
CTC0
CS02
CS01
CS00
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
Bit
7
6
5
4
3
2
1
0
$25 ($45)
–
PWM2
COM21
COM20
CTC2
CS22
CS21
CS20
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
TCCR0
TCCR2
• Bit 7 – Res: Reserved Bit
This bit is a reserved bit in the ATmega103(L) and always reads as zero.
• Bit 6 – PWM0/PWM2: Pulse Width Modulator Enable
When set (one), this bit enables PWM mode for Timer/Counter0 or Timer/Counter2.
This mode is described on page 43.
• Bits 5, 4 – COM01, COM00/COM21, COM20: Compare Output Mode, Bits 1 and 0
The COMn1 and COMn0 control bits determine any output pin action following a compare match in Timer/Counter2. Any output pin actions affect pins PB4 (OC0/PWM0) or
PB7 (OC2/PWM2). Since this is an alternative function to an I/O port, the corresponding
direction control bit must be set (one) to control an output pin. The control configuration
is shown in Table 10.
Table 10. Compare Mode Select
COMn1
COMn0
0
0
Timer/Counter disconnected from output pin OCn/PWMn
0
1
Toggle the OCn/PWMn output line.
1
0
Clear the OCn/PWMn output line (to zero).
1
1
Set the OCn/PWMn output line (to one).
Note:
Description
n = 0 or 2
In PWM mode, these bits have a different function. Refer to Table 13 for a detailed
description.
• Bit 3 – CTC0/CTC2: Clear Timer/Counter on Compare Match
When the CTC0 or CTC2 control bit is set (one), the Timer/Counter is reset to $00 in the
CPU clock cycle after a compare match. If the control bit is cleared, the Timer continues
counting and is unaffected by a compare match. Since the compare match is detected in
the CPU clock cycle following the match, this function will behave differently when a
prescaling higher than 1 is used for the Timer. When a prescaling of 1 is used and the
Compare Register is set to C, the Timer will count as follows if CTC0/2 is set:
... | C-2 | C-1 | C | 0 | 1 | ...
When the prescaler is set to divide by 8, the Timer will count like this:
... | C-2, C-2, C-2, C-2, C-2, C-2, C-2, C-2 | C-1, C-1, C-1, C-1, C-1, C-1, C-1, C-1 | C, 0,
0, 0, 0, 0, 0, 0 | 1, 1, 1, ...
41
0945I–AVR–02/07
In PWM mode, this bit has no effect.
• Bits 2, 1, 0 – CS02, CS01, CS00/CS22, CS21, CS20: Clock Select Bits 2, 1 and 0
The Clock Select2 bits 2, 1 and 0 define the prescaling source of the Timer/Counter.
Table 11. Timer/Counter0 Prescale Select
CS02
CS01
CS00
Description
0
0
0
Timer/Counter0 is stopped.
0
0
1
PCK0
0
1
0
PCK0/8
0
1
1
PCK0/32
1
0
0
PCK0/64
1
0
1
PCK0/128
1
1
0
PCK0/256
1
1
1
PCK0/1024
Table 12. Timer/Counter2 Prescale Select
CS22
CS21
CS20
Description
0
0
0
Timer/Counter2 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 PD7(T2), falling edge
1
1
1
External Pin PD7(T2), rising edge
The Stop condition provides a Timer Enable/Disable function. The CK down divided
modes are scaled directly from the CK CPU clock. If the external pin modes are used for
Timer/Counter2, transitions on PD7/(T2) will clock the counter even if the pin is configured as an output. This feature can give the user software control of the counting.
Timer/Counter0 – TCNT0
Bit
7
6
5
4
3
2
1
0
$32 ($42)
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
7
6
5
4
3
2
1
TCNT0
Timer/Counter2 – TCNT2
Bit
42
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
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
These 8-bit registers contain the value of the Timer/Counters.
Both Timer/Counters are realized as up or up/down (in PWM mode) counters with read
and write access. If the Timer/Counter is written to and a clock source is selected, it continues counting in the timer clock cycle after it is preset with the written value.
Timer/Counter0 Output
Compare Register – OCR0
Timer/Counter2 Output
Compare Register – OCR2
Bit
7
6
5
4
3
2
1
0
$31 ($51)
MSB
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
7
6
5
4
3
2
1
Bit
LSB
OCR0
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 Registers are 8-bit read/write registers.
The Timer/Counter Output Compare Registers contain the data to be continuously compared with the Timer/Counter. Actions on compare matches are specified in TCCR0 and
TCCR2. A compare match does only occur if the Timer/Counter counts to the OCR
value. A software write that sets the Timer/Counter and Output Compare Register to the
same value does not generate a compare match.
A compare match will set the Compare Interrupt Flag in the CPU clock cycle following
the compare event.
Timer/Counters 0 and 2 in
PWM Mode
When the PWM mode is selected, the Timer/Counter and the Output Compare Register
(OCR0 or OCR2) form an 8-bit, free-running, glitch-free and phase correct PWM with
outputs on the PB4(OC0/PWM0) or PB7(OC2/PWM2) pin. 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 PB4(OC0/PWM0) or PB7(OC2/PWM2) pin is set or
cleared according to the settings of the COM01/COM00 or COM21/COM20 bits in the
Timer/Counter Control Registers TCCR0 and TCCR2. Refer to Table 13 for details.
Table 13. Compare Mode Select in PWM Mode
COMn1
COMn0
0
0
Not connected
0
1
Not connected
1
0
Cleared on compare match, up-counting. Set on compare match, downcounting (non-inverted PWM).
1
1
Cleared on compare match, down-counting. Set on compare match, upcounting (inverted PWM).
Note:
Effect on Compare/PWM Pin
n = 0 or 2
Note that in PWM mode, the Output Compare Register is transferred to a temporary
location when written. The value is latched when the Timer/Counter reaches $FF. This
prevents the occurrence of odd-length PWM pulses (glitches) in the event of an unsynchronized OCR0 or OCR2 write. See Figure 32 for an example.
43
0945I–AVR–02/07
Figure 32. Effects on Unsynchronized OCR Latching
Compare Value changes
Counter Value
Compare Value
PWM Output
Synchronized OCR Latch
Compare Value changes
Counter Value
Compare Value
PWM Output
Glitch
Unsynchronized OCR Latch
During the time between the write and the latch operation, a read from OCR0 or OCR2
will read the contents of the temporary location. This means that the most recently written value always will read out of OCR0/2.
When the OCR Register (not the temporary register) is updated to $00 or $FF, the PWM
output changes to low or high immediately according to the settings of COM21/COM20
or COM11/COM10. This is shown in Table 14.
Table 14. PWM Outputs OCRn = $00 or $FF
COMn1
COMn0
OCRn
Output PWMn
1
0
$00
L
1
0
$FF
H
1
1
$00
H
1
1
$FF
L
Note:
n = 0 or 2
In PWM mode, the Timer Overflow Flag, TOV0 or TOV2, is set when the counter
advances from $00. Timer Overflow Interrupts 0 and 2 operate exactly as in normal
Timer/Counter mode, i.e., it is executed when TOV0 or TOV2 is set, provided that Timer
Overflow interrupt and Global Interrupts are enabled. This also applies to the Timer Output Compare Flags and interrupts.
The frequency of the PWM will be Timer Clock Frequency divided by 510.
Asynchronous Status
Register – ASSR
Bit
7
6
5
4
3
2
1
0
$30 ($50)
–
–
–
–
AS0
TCN0UB
OCR0UB
TCR0UB
Read/Write
R
R
R
R
R/W
R
R
R
Initial Value
0
0
0
0
0
0
0
0
ASSR
• Bits 7..4 – Res: Reserved Bits
These bits are reserved bits in the ATmega103(L) and always read as zero.
44
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
• Bit 3 – AS0: Asynchronous Timer/Counter0
When set (one), Timer/Counter0 is clocked from the TOSC1 pin. When cleared (zero),
Timer/Counter0 is clocked from the internal system clock, CK. When the value of this bit
is changed, the contents of TCNT0 might get corrupted.
• Bit 2 – TCN0UB: Timer/Counter0 Update Busy
When Timer/Counter0 operates asynchronously and TCNT0 is written, this bit becomes
set (one). When TCNT0 has been updated from the temporary storage register, this bit
is cleared (zero) by hardware. A logical “0” in this bit indicates that TCNT0 is ready to be
updated with a new value.
• Bit 1 – OCR0UB: Output Compare Register0 Update Busy
When Timer/Counter0 operates asynchronously and OCR0 is written, this bit becomes
set (one). When OCR0 has been updated from the temporary storage register, this bit is
cleared (zero) by hardware. A logical “0” in this bit indicates that OCR0 is ready to be
updated with a new value.
• Bit 0 – TCR0UB: Timer/Counter Control Register0 Update Busy
When Timer/Counter0 operates asynchronously and TCCR0 is written, this bit becomes
set (one). When TCCR0 has been updated from the temporary storage register, this bit
is cleared (zero) by hardware. A logical “0” in this bit indicates that TCCR0 is ready to be
updated with a new value.
If a write is performed to any of the three Timer/Counter0 Registers while its update
busy flag is set (one), the updated value might get corrupted and cause an unintentional
interrupt to occur.
When reading TCNT0, OCR0 and TCCR0, there is a difference in result. When reading
TCNT0, the actual timer value is read. When reading OCR0 or TCCR0, the value in the
temporary storage register is read.
Asynchronous Operation of
Timer/Counter0
When Timer/Counter0 operates synchronously, all operations and timing are identical to
Timer/Counter2. During asynchronous operation, however, some considerations must
be taken.
•
WARNING: When switching between asynchronous and synchronous clocking of
Timer/Counter0, the Timer Registers TCNT0, OCR0 and TCCR0 might get
corrupted. The following is the safe procedure for switching clock source:
1. Disable the Timer0 interrupts OCIE0 and TOIE0.
2. Select clock source by setting ASO as appropriate.
3. Write new values to TCNT0, OCR0 and TCCR0.
4. If switching to asynchronous operation, wait for TCNT0UB, OCR0UB and
TCR0UB to be cleared.
5. Clear the Timer/Counter0 Interrupt Flags.
6. Enable interrupts if needed.
•
The Oscillator is optimized for use with a 32,768 Hz watch crystal. An external clock
signal applied to this pin goes through the same amplifier having a bandwidth of
256 kHz. The external clock signal should therefore be in the interval 0 Hz 256 kHz. The frequency of the clock signal applied to the TOSC1 pin must be lower
than one fourth of the CPU main clock frequency. Observe that CPU clock
frequency can be lower than the XTAL frequency if the XTAL divider is enabled.
45
0945I–AVR–02/07
•
When writing to one of the registers TCNT0, OCR0 or TCCR0, 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 TCNT0 does not
disturb an OCR0 write in progress. To detect that a transfer to the destination
register has taken place, an Asynchronous Status Register (ASSR) has been
implemented.
•
When entering Power-save mode after having written to TCNT0, OCR0 or TCCR0,
the user must wait until the written register has been updated if Timer/Counter0 is
used to wake up the device. Otherwise, the MCU will go to sleep before the changes
have had any effect. This is extremely important if the Output Compare0 interrupt is
used to wake up the device; Output Compare is disabled during write to OCR0 or
TCNT0. If the write cycle is not finished (i.e., the user goes to sleep before the
OCR0UB bit returns to zero), the device will never get a compare match and the
MCU will not wake up.
•
If Timer/Counter0 is used to wake up the device from Power-save mode,
precautions must be taken if the user wants to reenter Power-save mode: The
interrupt logic needs one TOSC1 cycle to get reset. If the time between wake-up
and reentering 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 TCCR0, TCNT0 or OCR0.
2. Wait until the corresponding Update Busy Flag in ASSR returns to zero.
3. Enter Power-save mode.
46
•
When asynchronous operation is selected, the 32 kHz Oscillator for Timer/Counter0
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/Counter0 after Power-up or wake-up from Power-down.
The content of all Timer/Counter0 Registers must be considered lost after a wakeup from Power-down due to the unstable clock signal upon start-up, no matter
whether the Oscillator is in use or a clock signal is applied to the TOSC pin.
•
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
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. To execute the
corresponding Timer/Counter0 interrupt routine, the Global Interrupt bit in SREG
must have been set. Otherwise, the part will still wake up from Power-down, but
continues to execute the Sleep command. The Interrupt Flags are updated three
processor cycles after the processor clock has started. During these cycles, the
processor executes instructions, but the interrupt condition is not readable and the
interrupt routine has not started yet.
•
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 of which TCNT0 will read as the same value as before Power-
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
save mode was entered. After an edge on the asynchronous clock, TCNT0 will read
correctly. (The compare and overflow functions of the Timer are not affected by this
behavior.) Safe procedure to ensure correct value is read:
1. Write any value to either of the registers OCR0 or TCCR0
2. Wait for the corresponding Update Busy Flag to be cleared
3. Read TCNT0
Note that OCR0 and TCCR0 are never modified by hardware, and will always read
correctly.
16-bit Timer/Counter1
Figure 33 shows the block diagram for Timer/Counter1.
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 the specification for the
Timer/Counter1 Control Register (TCCR1B). 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
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
Registers 1A and 1B (OCR1A and OCR1B) as the data sources to be compared to the
Timer/Counter1 contents. The Output Compare functions include optional clearing of
the counter on Compare A Match, and actions on the Output Compare pins on both
compare matches.
47
0945I–AVR–02/07
Figure 33. Timer/Counter1 Block Diagram
TOV0
8 7
CS11
CS10
CS12
CTC1
ICNC1
ICES1
PWM11
T/C1 CONTROL
REGISTER B (TCCR1B)
PWM10
COM1B1
COM1B0
COM1A1
TOV1
OCF1B
OCF1A
ICF1
T/C1 CONTROL
REGISTER A (TCCR1A)
COM1A0
OCF0
TOV1
OCF1B
T/C1 COMPARE T/C1 INPUT
MATCHB IRQ CAPTURE IRQ
TIMER INT. FLAG
REGISTER (TIFR)
TIMER INT. MASK
REGISTER (TIMSK)
15
OCF1A
TOV2
OCF2
OCIE0
TOIE0
TOIE1
OCIE1A
OCIE1B
TICIE1
TOIE2
OCIE2
8-BIT DATA BUS
ICF1
T/C1 COMPARE
MATCHA IRQ
T/C1 OVERFLOW IRQ
0
T/C1 INPUT CAPTURE REGISTER (ICR1)
CK
CONTROL
LOGIC
T1
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
Timer/Counter1 can also be used as an 8-, 9- or 10-bit Pulse Width Modulator. In this
mode the counter and the OCR1A/OCR1B Registers serve as a dual glitch-free standalone PWM with centered pulses. Refer to page 53 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 – PD4/(IC1). 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 “Analog Comparator” on page 75 for details on
this. The ICP pin logic is shown in Figure 34.
Figure 34. ICP Pin Schematic Diagram
48
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
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.
Timer/Counter1 Control
Register A – TCCR1A
Bit
7
6
5
4
3
2
1
0
COM1A1
COM1A0
COM1B1
COM1B0
–
–
PWM11
PWM10
Read/Write
R/W
R/W
R/W
R/W
R
R
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 pin 1. 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 15
• 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. Since this is an alternative function to an I/O port, the corresponding direction control bit must be set (one) to control an output pin. The control configuration is
given in Table 15.
Table 15. Compare1 Mode Select
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
X = A or B.
In PWM mode, these bits have a different function. Refer to Table 16 for a detailed
description.
• Bits 3..2 – Res: Reserved Bits
These bits are reserved bits in the ATmega103(L) and always read as zero.
• Bits 1..0 – PWM11, PWM10: Pulse Width Modulator Select Bits
These bits select PWM operation of Timer/Counter1 as specified in Table 18 on page
53. This mode is described on page 53.
Table 16. PWM Mode Select
PWM11
PWM10
0
0
Description
PWM operation of Timer/Counter1 is disabled.
49
0945I–AVR–02/07
Table 16. PWM Mode Select
Timer/Counter1 Control
Register B – TCCR1B
PWM11
PWM10
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
Input Capture pin PD4(IC1) as specified. When the ICNC1 bit is set (one), four successive samples are measured on PD4(IC1), 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 – PD4(IC1).
While the ICES1 bit is set (one), the Timer/Counter1 contents are transferred to the
Input Capture Register on the rising edge of the Input Capture pin – PD4(IC1).
• Bits 5, 4 – Res: Reserved Bits
These bits are reserved bits in the ATmega103(L) 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. Since the compare match is
detected in the CPU clock cycle following the match, this function will behave differently
when a prescaling higher than 1 is used for the Timer. 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-2 | C-1 | C | 0 | 1 | ...
When the prescaler is set to divide by 8, the Timer will count like this:
... | C-2, C-2, C-2, C-2, C-2, C-2, C-2, C-2 | C-1, C-1, C-1, C-1, C-1, C-1, C-1, C-1 | C, 0,
0, 0, 0, 0, 0, 0 | ...
In PWM mode, this bit has no effect.
50
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
• Bits 2, 1, 0 – CS12, CS11, CS10: Clock Select1, Bits 2, 1 and 0
The lock Select1 bits 2, 1 and 0 define the prescaling source of Timer/Counter1.
Table 17. Clock1 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 CK down divided
modes are scaled directly from the CK CPU clock. If the external pin modes are used for
Timer/Counter1, transitions on PD6/(T1) will clock the counter even if the pin is configured as an output. This feature can give the user software control of the counting.
Timer/Counter1 – TCNT1H
and TCNT1L
Bit
15
$2D ($4D)
14
13
12
11
10
9
TCNT1H
$2C ($4C)
Read/Write
Initial Value
8
MSB
LSB
7
6
5
4
3
2
1
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
TCNT1L
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 interrupt routines perform access to registers using
TEMP, interrupts must be disabled during access from the main program (and from
interrupt routines if interrupts are allowed from within interrupt routines).
•
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. When using
Timer/Counter1 as an 8-bit Timer, it is sufficient to write the Low Byte only.
•
TCNT1 Timer/Counter1 Read:
When the CPU reads the Low Byte TCNT1L, the data of 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
51
0945I–AVR–02/07
full 16-bit register read operation. When using Timer/Counter1 as an 8-bit Timer, it
is sufficient to read the Low Byte only.
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 clock cycle after it is preset with the written
value.
Timer/Counter1 Output
Compare Register – OCR1AH
and OCR1AL
Bit
$2B
15
14
13
12
11
10
9
OCR1AH
$2A
LSB
7
6
5
4
3
2
1
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
Bit
15
14
13
12
11
10
9
8
$29
MSB
Read/Write
Initial Value
Timer/Counter1 Output
Compare Register – OCR1BH
and OCR1BL
8
MSB
OCR1BH
$28
Read/Write
Initial Value
OCR1AL
LSB
7
6
5
4
3
2
1
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
OCR1BL
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 Registers. A compare match occurs only if
Timer/Counter1 counts to the OCR value. A software write that sets TCNT1 and OCR1A
or OCR1B to the same value does not generate a compare match.
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.
The TEMP Register is also used when accessing TCNT1 and ICR1. If the main program
and interrupt routines perform access to registers using TEMP, interrupts must be disabled during access from the main program.
Timer/Counter1 Input Capture
Register – ICR1H and ICR1L
Bit
$27 ($37)
15
14
13
12
11
10
9
ICR1H
$26 ($36)
LSB
7
52
8
MSB
6
5
4
3
2
1
ICR1L
0
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Read/Write
Initial Value
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
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 – PD4(IC1) – is detected, the current value of the
Timer/Counter1 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 interrupt routines perform access to registers using TEMP, interrupts
must be disabled during access from the main program.
Timer/Counter1 in PWM Mode
When the PWM mode is selected, Timer/Counter1, 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 PB5(OC1A) and
PB6(OC1B) pins. 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 10 least significant bits of
OCR1A or OCR1B, the PB5(OC1A)/PB6(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 19 for details.
Table 18. Timer TOP Values and PWM Frequency
PWM Resolution
Timer TOP value
Frequency
8-bit
$00FF (255)
fTCK1/510
9-bit
$01FF (511)
fTCK1/1022
10-bit
$03FF (1023)
fTCK1/2046
Table 19. Compare1 Mode Select in PWM Mode
COM1X1
COM1X0
0
0
Not connected
0
1
Not connected
1
0
Cleared on compare match, up-counting. Set on compare match,
down-counting (non-inverted PWM).
1
1
Cleared on compare match, down-counting. Set on compare match,
up-counting (inverted PWM).
Note:
Effect on OCX1
X = A or B
Note that in the PWM mode, the 10 least significant OCR1A/OCR1B bits, when written,
are transferred to a temporary location. They are latched when Timer/Counter1 reaches
53
0945I–AVR–02/07
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 for an example.
Figure 35. Effects on Unsynchronized OCR1 Latching
Compare Value changes
Counter Value
Compare Value
PWM Output OC1X
Synchronized
OCR1X Latch
Compare Value changes
Counter Value
Compare Value
PWM Output OC1X
Unsynchronized
OCR1X Latch
Glitch
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 OCR1A/OCR1B contains $0000 or TOP, 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 20.
Note:
If the Compare Register contains the TOP value and the prescaler is not in use
(CS12..CS10 = 001), the PWM output will not produce any pulse at all, because the upcounting and down-counting value is reached simultaneously. When the prescaler is in
use (CS12..CS10 ≠ 001 or 000), the PWM output goes active when the counter reaches
the TOP value, but the down-counting compare match is not interpreted to be reached
before the next time the counter reaches the TOP value, making a one-period PWM
pulse.
Table 20. PWM Outputs OCR1X = $0000 or TOP
Note:
COM1X1
COM1X0
OCR1X
Output OC1X
1
0
$0000
L
1
0
TOP
H
1
1
$0000
H
1
1
TOP
L
X = A or B
In PWM mode, the Timer Overflow Flag1, TOV1, is set when the counter advances from
$0000. 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 does also apply to the Timer Output Compare1 flags and
interrupts.
54
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Watchdog Timer
The Watchdog Timer is clocked from a separate On-chip Oscillator. By controlling the
Watchdog Timer prescaler, the Watchdog Reset interval can be adjusted as shown in
Table 21. See characterization data for typical values at other VCC levels. The WDR
(Watchdog Reset) instruction resets the Watchdog Timer. From the Watchdog Reset,
eight different clock cycle periods can be selected to determine the reset period. If the
reset period expires without another Watchdog Reset, the ATmega103(L) resets and
executes from the Reset Vector. For timing details on the Watchdog Reset, refer to
page 29.
To prevent unintentional disabling of the Watchdog, a special turn-off procedure must
be followed when the Watchdog is disabled. Refer to the description of the Watchdog
Timer Control Register for details.
Figure 36. Watchdog Timer
Oscillator
1 MHz at VCC = 5V
350 kHz at VCC = 3V
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 ATmega103(L) 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:
55
0945I–AVR–02/07
1. In the same operation, write a logical “1” to WDTOE and WDE. A logical “1” 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
Time-out periods are shown in Table 21.
Table 21. Watchdog Timer Prescale Select
Typical Time-out
at VCC = 3.0V
Typical Time-out
at VCC = 5.0V
16K cycles
47 ms
15 ms
1
32K cycles
94 ms
30 ms
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
2,048K cycles
6.0 s
1.9 s
WDP2
WDP1
WDP0
0
0
0
0
0
0
1
Note:
56
Number of WDT
Oscillator Cycles
The frequency of the Watchdog Oscillator is voltage-dependent as shown in the Electrical Characteristics section.
The WDR (Watchdog Reset) instruction should always be executed before the Watchdog
Timer is enabled. This ensures that the reset period will be in accordance with the
Watchdog Timer prescale settings. If the Watchdog Timer is enabled without reset, the
Watchdog Timer may not start counting from zero.
To avoid unintentional MCU Reset, the Watchdog Timer should be disabled or reset
before changing the Watchdog Timer Prescale Select.
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
EEPROM Read/Write
Access
The EEPROM Access Registers are accessible in the I/O space.
The write access time is in the range of 2.5 - 4 ms, depending on the VCC voltages. A
self-timing function lets the user software detect when the next byte can be written. A
special EEPROM Ready interrupt can be set to trigger when the EEPROM is ready to
accept new data.
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 written, the CPU is halted for two clock cycles before the next
instruction is executed. When it is read, the CPU is halted for four clock cycles.
EEPROM Address Register –
EEARH, EEARL
Bit
15
14
13
12
11
10
9
8
$1F ($3F)
–
–
–
–
EEAR11
EEAR10
EEAR9
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/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 EEPROM Address Registers (EEARH and EEARL) specify the EEPROM address
in the 4 KB EEPROM space. The EEPROM Data bytes are addressed linearly between
0 and 4095.
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.
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 ATmega103(L) and will always be 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
constantly generates an interrupt request when EEWE is cleared (zero).
57
0945I–AVR–02/07
• 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 a 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 “1” 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 unessential):
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 “1” to the EEMWE bit in EECR (to be able to write an logical “1” to
the EEMWE bit, the EEWE bit must be written to zero in the same cycle).
5. Within four clock cycles after setting EEMWE, write a logical “1” 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 and EEDR Registers 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 (typically 2.5 ms at VCC = 5V or 4 ms at VCC = 2.7V) 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 two 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 four cycles before the next instruction is executed.
The user should poll the EEWE bit before starting the read operation. If a write operation
is in progress when new data or address is written to the EEPROM I/O Registers, the
write operation will be interrupted and the result is undefined.
58
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Prevent EEPROM
Corruption
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. Second, 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 is best done by an external low VCC Reset Protection circuit, often
referred to as a Brown-out Detector (BOD). Please refer to application note “AVR
180” for design considerations regarding Power-on Reset and low-voltage
detection.
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 cannot be updated by the CPU and will
not be subject to corruption.
59
0945I–AVR–02/07
Serial Peripheral
Interface – SPI
The Serial Peripheral Interface (SPI) allows high-speed synchronous data transfer
between the ATmega103(L) and peripheral devices or between several AVR devices.
The ATmega103(L) SPI features include the following:
•
•
•
•
•
•
•
Full-duplex, Three-wire Synchronous Data Transfer
Master or Slave Operation
LSB First or MSB First Data Transfer
Four Programmable Bit Rates
End-of-Transmission Interrupt Flag
Write Collision Flag Protection
Wake-up from Idle Mode (Slave Mode only)
Figure 37. SPI Block Diagram
The interconnection between Master and Slave CPUs with SPI is shown in Figure 38.
The PB1 (SCK) pin is the clock output in the Master mode and is 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 PB2 (MOSI) pin and into the PB2 (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, PB0(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 38. When data is shifted from the Master to the Slave, data is also shifted in
the opposite direction, simultaneously. This means that during one shift cycle, data in
the Master and the Slave are interchanged.
60
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 38. SPI Master-Slave Interconnection
MSB
MASTER
LSB
MSB
MISO MISO
SLAVE
LSB
8-BIT SHIFT REGISTER
8-BIT SHIFT REGISTER
MOSI MOSI
SPI
CLOCK GENERATOR
SCK
SS
SCK
SS
VCC
The system is single-buffered in the transmit direction and double-buffered in the
receive direction. This means that characters to be transmitted cannot be written to the
SPI Data Register before the entire shift cycle is completed. When receiving data, however, a received byte must be read from the SPI Data Register before the next byte 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 the following table:
Table 22. SPI Pin Overrides
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
See “Alternate Functions of Port B” on page 89 for a detailed description and 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 that 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 Master with the SS pin defined as an input, the SPI system interprets this as another Master selecting the SPI as a Slave and starts 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 transmittal 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. Once the MSTR bit has been cleared by a Slave Select, it must be set by the
user to re-enable SPI Master mode.
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
61
0945I–AVR–02/07
the SS pin is brought high. If the SS pin is brought 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 that
are determined by control bits CPHA and CPOL. The SPI data transfer formats are
shown in Figure 39 and Figure 40.
Figure 39. SPI Transfer Format with CPHA = 0 and DORD = 0
SCK CYCLE #
(FOR REFERENCE)
1
2
3
4
5
6
7
8
SCK (CPOL=0)
SCK (CPOL=1)
MOSI
(FROM MASTER)
MSB
MISO
(FROM SLAVE)
MSB
6
5
4
3
2
1
LSB
6
5
4
3
2
1
LSB
*
SS (TO SLAVE)
SAMPLE
* Not defined but normally MSB of character just received.
Figure 40. SPI Transfer Format with CPHA = 1 and DORD = 0
SCK CYCLE #
(FOR REFERENCE)
1
2
7
6
5
4
3
8
SCK (CPOL=0)
SCK (CPOL=1)
MOSI
(FROM MASTER)
MISO
(FROM SLAVE)
*
MSB
6
5
4
3
2
1
MSB
6
5
4
3
2
1
LSB
LSB
SS (TO SLAVE)
SAMPLE
* Not defined but normally LSB of previously transmitted character.
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 Global Interrupts are enabled.
• Bit 6 – SPE: SPI Enable
When the SPE bit is set (one), the SPI is enabled and SS, MOSI, MISO and SCK are
connected to pins PB0, PB1, PB2 and PB3.
62
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
• 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 39 and Figure 40 for additional information.
• Bit 2 – CPHA: Clock Phase
Refer to Figure 39 or Figure 40 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 CPU Clock
frequency (fcl) is shown in Table 23.
Table 23. Relationship between SCK and the Oscillator Frequency
Note:
SPR1
SPR0
SCK Frequency
0
0
0
1
1
0
1
1
fcl/4
fcl/16
fcl/64
fcl/128
Observe that CPU clock frequency can be lower than the XTAL frequency if the XTAL
divider is enabled.
SPI Status Register – SPSR
Bit
7
6
5
4
3
2
1
SPIF
WCOL
–
–
–
–
–
–
Read/Write
R
R
R
R
R
R
R
R
Initial Value
0
0
0
0
0
0
0
0
$0E
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. 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).
• 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.
63
0945I–AVR–02/07
• Bits 5..0 – Res: Reserved Bits
These bits are reserved bits in the ATmega103(L) and will always read as zero.
64
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
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.
65
0945I–AVR–02/07
UART
The ATmega103(L) features a full duplex (separate Receive and Transmit Registers)
Universal Asynchronous Receiver and Transmitter (UART). The main features are:
• Baud Rate Generator that can Generate a large Number of Baud Rates (bps)
• 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
Data Transmission
A block schematic of the UART Transmitter is shown in Figure 41.
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:
•
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.
If the 10(11)-bit Transmit Shift Register is empty, data is transferred from UDR to the
Shift Register. At this time 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. Writing to UDR clears UDRE. 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.
66
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 41. UART Transmitter
DATA BUS
XTAL
BAUD RATE
GENERATOR
BAUD x 16
/16
UART I/O DATA
REGISTER (UDR)
STORE UDR
SHIFT ENABLE
PIN CONTROL
LOGIC
BAUD
CONTROL LOGIC
1
10(11)-BIT TX
SHIFT REGISTER
TXD
RXCIE
TXCIE
UDRIE
UART CONTROL
REGISTER (UCR)
DATA BUS
RXC
TXC
UDRE
FE
OR
UART STATUS
REGISTER (USR)
TXC
UDRE
RXEN
TXEN
CHR9
RXB8
TXB8
IDLE
TXC
IRQ
UDRE
IRQ
On the baud rate clock following the transfer operation to the Shift Register, the start bit
is shifted out on the TXD pin, followed by 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. In this
case, after the stop bit has been present on TXD for one bit length, the TX 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 PE1 pin can be used for general I/O. When TXEN is set, the UART
Transmitter will be connected to PE1, which is forced to be an output pin regardless of
the setting of the DDE1 bit in DDRE.
67
0945I–AVR–02/07
Data Reception
Figure 42. UART Receiver
DATA BUS
XTAL
BAUD RATE
GENERATOR
BAUD X 16
UART I/O DATA
REGISTER (UDR)
BAUD
/16
STORE UDR
PIN CONTROL
LOGIC
10(11)-BIT RX
SHIFT REGISTER
UART STATUS
REGISTER (USR)
RXC
RXCIE
TXCIE
UDRIE
UART CONTROL
REGISTER (UCR)
RXC
TXC
UDRE
FE
DOR
DATA RECOVERY
LOGIC
RXEN
TXEN
CHR9
RXB8
TXB8
RXD
DATA BUS
RXC
IRQ
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 “0” 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 “1”s, 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 43.
68
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 43. Sampling Received Data
RXD
START BIT
D0
D1
D2
D3
D4
D5
D6
D7
STOP BIT
RECEIVER
SAMPLING
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 “0”s, the Framing Error (FE) Flag
in the UART Status Register (USR) is set when the received byte is transferred to UDR.
Before reading the UDR Register, the user should always check the FE bit to detect
Framing Errors. FE is cleared when UDR is read.
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 9 in the Transmit Shift
Register when data is transferred to UDR.
If, after having received a character, the UDR Register has not been accessed since the
last receive, the OverRun (OR) flag in USR is set. This means that the new data transferred to the Shift Register could not be transferred to UDR and is lost. The OR bit is
buffered, and is available when the valid data byte in UDR has been read. The user
should always check the OR after reading from 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 PE0 pin can be used as a general I/O pin. When RXEN is set, the UART
Receiver will be connected to PE0, which is forced to be an input pin regardless of the
setting of the DDE0 bit in DDRE. When PE0 is forced to input by the UART, the
PORTE0 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 bits long plus start and stop bits. The 9th 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.
69
0945I–AVR–02/07
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 Status Register – USR
Bit
7
6
5
4
3
2
1
$0B ($2B)
RXC
TXC
UDRE
FE
OR
–
–
0
–
Read/Write
R
R/W
R
R
R
R
R
R
Initial Value
0
0
1
0
0
0
0
0
USR
The USR Register is a read-only register providing information on the UART Status.
• 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 the 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.
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
“1” 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.
70
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
• 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 is transferred from the
Receiver Shift Register. The OR bit is buffered, which means that it will be set once the
valid data still in UDRE is read.
The OR bit is cleared (zero) when data is received and transferred to UDR.
• Bits 2..0 – Res: Reserved Bits
These bits are reserved bits in the ATmega103(L) and will always read as zero.
UART Control Register – UCR
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
UCR
• 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 nine bits 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.
71
0945I–AVR–02/07
• 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.
72
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Baud Rate Generator
The baud rate generator is a frequency divider that generates baud rates according to
the following equation:
f CK
BAUD = ------------------------------------16 ( UBRR + 1 )
•
BAUD = baud rate
•
fCK = CPU clock frequency
•
UBRR = contents of the UART Baud Rate Register, UBRR (0 - 255)
For standard crystal frequencies, the most commonly used baud rates can be generated
by using the UBRR settings in Table 24. Observe that CPU clock frequency can be
lower than the XTAL frequency if the XTAL divider is enabled. UBRR values that yield an
actual baud rate differing less than 2% from the target baud rate are in boldface in the
table. However, using baud rates that have more than 1% error is not recommended.
High error ratings give less noise resistance.
73
0945I–AVR–02/07
Table 24. UBRR Settings at Various CPU Frequencies
Baud Rate
2400
4800
9600
14400
19200
28800
38400
57600
76800
115200
1 MHz %Error 1.8432 MHz %Error
2 MHz %Error 2.4576 MHz %Error
UBRR=
25
0.2 UBRR=
47
0.0 UBRR=
51
0.2 UBRR=
63
0.0
UBRR=
12
0.2 UBRR=
23
0.0 UBRR=
25
0.2 UBRR=
31
0.0
UBRR=
6
7.5 UBRR=
11
0.0 UBRR=
12
0.2 UBRR=
15
0.0
UBRR=
3
7.8 UBRR=
UBRR=
8
3.7
UBRR=
10
3.1
7
0.0
UBRR=
2
7.8 UBRR=
6
7.5 UBRR=
5
0.0 UBRR=
7
0.0
UBRR=
1
7.8 UBRR=
3
7.8 UBRR=
4
6.3
3
0.0 UBRR=
UBRR=
1
22.9 UBRR=
2
7.8 UBRR=
2
0.0 UBRR=
3
0.0
UBRR=
0
7.8 UBRR=
1
7.8 UBRR=
2
12.5
1
0.0 UBRR=
UBRR=
0
22.9 UBRR=
1
33.3 UBRR=
1
22.9 UBRR=
1
0.0
UBRR=
0
84.3 UBRR=
0
7.8 UBRR=
0
25.0
0
0.0 UBRR=
Baud Rate
2400
4800
9600
14400
19200
28800
38400
57600
76800
115200
3.2768 MHz %Error 3.6864 MHz %Error
4 MHz %Error
4.608 MHz %Error
UBRR=
84
0.4 UBRR=
95
0.0 UBRR= 103
0.2 UBRR= 119
0.0
UBRR=
42
0.8 UBRR=
47
0.0 UBRR=
51
0.2 UBRR=
59
0.0
UBRR=
20
1.6 UBRR=
23
0.0 UBRR=
25
0.2 UBRR=
29
0.0
16
2.1 UBRR=
UBRR=
13
1.6 UBRR=
15
0.0 UBRR=
19
0.0
UBRR=
10
3.1 UBRR=
11
0.0 UBRR=
12
0.2 UBRR=
14
0.0
UBRR=
8
3.7 UBRR=
6
1.6 UBRR=
7
0.0 UBRR=
9
0.0
UBRR=
4
6.3 UBRR=
6
7.5 UBRR=
7
6.7
5
0.0 UBRR=
UBRR=
3
12.5 UBRR=
3
7.8 UBRR=
3
0.0 UBRR=
4
0.0
UBRR=
2
12.5 UBRR=
2
7.8 UBRR=
3
6.7
2
0.0 UBRR=
UBRR=
1
12.5 UBRR=
1
7.8 UBRR=
2
20.0
1
0.0 UBRR=
Baud Rate
2400
4800
9600
14400
19200
28800
38400
57600
76800
115200
7.3728 MHz %Error
8 MHz %Error
9.216 MHz %Error 11.059 MHz %Error
UBRR= 191
0.0 UBRR= 207
0.2 UBRR= 239
0.0 UBRR= 287
UBRR=
95
0.0 UBRR= 103
0.2 UBRR= 119
0.0 UBRR= 143
0.0
UBRR=
47
0.0 UBRR=
51
0.2 UBRR=
59
0.0 UBRR=
71
0.0
UBRR=
31
0.0 UBRR=
34
0.8 UBRR=
39
0.0 UBRR=
47
0.0
UBRR=
23
0.0 UBRR=
25
0.2 UBRR=
29
0.0 UBRR=
35
0.0
UBRR=
16
2.1 UBRR=
15
0.0 UBRR=
19
0.0 UBRR=
23
0.0
UBRR=
14
0.0 UBRR=
17
0.0
11
0.0 UBRR=
12
0.2 UBRR=
UBRR=
8
3.7 UBRR=
7
0.0 UBRR=
9
0.0 UBRR=
11
0.0
UBRR=
6
7.5 UBRR=
7
6.7 UBRR=
5
0.0 UBRR=
8
0.0
UBRR=
3
7.8 UBRR=
3
0.0 UBRR=
4
0.0 UBRR=
5
0.0
UART Baud Rate Register –
UBRR
Bit
7
6
5
4
3
2
1
0
$09 ($29)
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
UBRR
The UBRR is an 8-bit read/write register that specifies the UART baud rate according to
the description on the previous page.
74
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Analog Comparator
The analog comparator compares the input values on the positive input PE2 (AC+) and
negative input PE3 (AC-). When the voltage on the positive input PE2 (AC+) is higher
than the voltage on the negative input PE3 (AC-), the Analog Comparator Output (ACO)
is set (one). The output of the comparator 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 44.
Figure 44. Analog Comparator Block Diagram
VCC
ACD
ACIE
PE2
(AC+)
+
-
PE3
(AC-)
ANALOG
COMPARATOR
IRQ
INTERRUPT
SELECT
ACI
ACIS1
ACIS0
ACIC
TO T/C1 CAPTURE
TRIGGER MUX
ACO
Analog Comparator Control
and Status Register – ACSR
Bit
7
6
5
4
3
2
1
0
$08 ($28)
ACD
–
ACO
ACI
ACIE
ACIC
ACIS1
ACIS0
Read/Write
R/W
R
R
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
X
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 – Res: Reserved Bit
This bit is a reserved bit in the ATmega103(L) and will always read as zero.
• 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 ACI1 and ACI0. 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 execut-
75
0945I–AVR–02/07
ing the corresponding interrupt handling vector. Alternatively, ACI is cleared by writing a
logical “1” to the flag. Observe, however, that if another bit in this register is modified
using the SBI or CBI instruction, ACI will be cleared if it has become set before the
operation.
• 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 25.
Table 25. 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.
Caution: Using the SBI or CBI instruction on other bits than ACI in this register will write
a one back into ACI if it is read as set, thus clearing the flag.
76
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Analog-to-Digital
Converter
Feature list:
•
•
•
•
•
•
•
•
10-bit Resolution
±2 LSB Absolute Accuracy
0.5 LSB Integral Non-linearity
70 - 280 µs Conversion Time
Up to 14 kSPS
8 Multiplexed Input Channels
Interrupt on ADC Conversion Complete
Sleep Mode Noise Canceler
The ATmega103(L) features a 10-bit successive approximation ADC. The ADC is connected to an 8-channel Analog Multiplexer, which allows each pin of Port F to be used
as an 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 45.
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 section “ADC Noise Canceling Techniques” on page 82 on how to connect
these pins.
An external reference voltage must be applied to the AREF pin. This voltage must be in
the range AGND - AVCC.
Figure 45. Analog-to-Digital Converter Block Schematic
ADC CONVERSION
COMPLETE IRQ
10-BIT DAC
Analog
Inputs
8CHANNEL
MUX
+
9
0
ADC DATA REGISTER
(ADCH/ADCL)
ADPS0
ADPS1
ADPS2
ADIF
ADIE
ADSC
ADC CTRL & STATUS
REGISTER (ADCSR)
ADEN
MUX0
MUX1
MUX2
ADC MULTIPLEXER
SELECT (ADMUX)
ADIE
ADIF
8-BIT DATA BUS
External
Reference
Voltage
CONVERSION LOGIC
SAMPLE & HOLD
COMPARATOR
77
0945I–AVR–02/07
Operation
The ADC operates in Single Conversion mode, and each conversion will have to be initiated by the user.
The ADC is enabled by writing a logical “1” to the ADC Enable bit, ADEN in ADCSR.
The first conversion that is started after enabling the ADC will be preceded by a dummy
conversion to initialize the ADC. To the user, the only difference will be that this conversion takes 13 more ADC clock pulses than a normal conversion (see Figure 48).
A conversion is started by writing a logical “1” to the ADC Start Conversion bit, ADSC.
This bit will stay high as long as the conversion is in progress and 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.
As the ADC generates a 10-bit result, two Data Registers, ADCH and ADCL, must be
read to get the result when the conversion is complete. Special data protection logic is
used to ensure that the contents of the Data Registers belong to the same result when
they are read. This mechanism works as follows:
When reading data, ADCL must be read first. 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, none of the registers are 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, ADIF, which can be triggered when a conversion completes. When ADC access to the Data Registers is prohibited between reading of ADCL
and ADCH, the interrupt will trigger even if the result is lost.
Prescaling
Figure 46. 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 ADC contains a prescaler, which divides the system clock to an acceptable ADC
clock frequency. The ADC accepts input clock frequencies in the range 50 - 200 kHz.
Applying a higher input frequency will result in poorer accuracy (see “ADC DC Characteristics” on page 83).
The ADPS0 - ADPS2 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
78
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
keeps running for as long as the ADEN bit is set and is continuously reset when ADEN
is low.
When initiating a conversion by setting the ADSC bit in ADCSR, the conversion starts at
the following falling edge of the ADC clock cycle. The actual sample-and-hold takes
place one ADC clock cycle after the start of the conversion. The result is ready and written to the ADC Result Register after 13 cycles. The ADC needs two more clock cycles
before a new conversion can be started. If ADSC is set high in this period, the ADC will
start the new conversion immediately. For a summary of conversion times, see Table
26.
Figure 47. ADC Timing Diagram, First Conversion
Cycle number
1
2
13
12
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
1
2
ADC clock
ADEN
ADSC
Hold strobe
ADIF
ADCH
MSB of result
ADCL
LSB of result
Dummy Conversion
Second
Conversion
Actual Conversion
Table 26. ADC Conversion Time
Sample
Cycle
Number
Result Ready
(Cycle
Number)
Total
Conversion
Time (Cycles)
Total
Conversion
Time (µs)
1st Conversion
14
26
28
140 - 560
Single Conversion
1
13
15
75 - 300
Condition
Figure 48. ADC Timing Diagram
Cycle number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1
2
ADC clock
ADSC
Hold strobe
ADIF
ADCH
MSB of result
ADCL
LSB of result
One Conversion
Next Conversion
79
0945I–AVR–02/07
ADC Noise Canceler
Function
The ADC features a noise canceler that enables conversion during Idle mode to reduce
noise induced from the CPU core. To make use of this feature, the following procedure
should be used:
1. Turn off the ADC by clearing ADEN.
2. Turn on the ADC and simultaneously start a conversion by setting ADEN and
ADSC. This starts a dummy conversion that will be followed by a valid
conversion.
3. Within 14 ADC clock cycles, enter Idle mode.
4. If no other interrupts occur before the ADC conversion completes, the ADC interrupt will wake up the MCU and execute the ADC conversion complete interrupt
routine.
ADC Multiplexer Select
Register – ADMUX
Bit
7
6
5
4
3
2
1
0
$07 ($27)
–
–
–
–
–
MUX2
MUX1
MUX0
Read/Write
R
R
R
R
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
ADMUX
• Bits 7..3 – Res: Reserved Bits
These bits are reserved bits in the ATmega103(L) and always read as zero.
• Bits 2..0 – MUX2..MUX0: Analog Channel Select Bits 2 - 0
The value of these three bits selects which analog input 7 - 0 is connected to the ADC.
ADC Control and Status
Register – ADCSR
Bit
7
6
5
4
3
2
1
0
ADEN
ADSC
–
ADIF
ADIE
ADPS2
ADPS1
ADPS0
Read/Write
R/W
R/W
R
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
A logical “1” must be written to this bit to start each 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, a dummy conversion will precede the initiated conversion. This
dummy conversion performs initialization of the ADC.
ADSC remains high during the conversion. ADSC goes low after the conversion is complete, but before the result is written to the ADC Data Registers. This allows a new
conversion to be initiated before the current conversion is complete. The new conversion will then start immediately after the current conversion completes. When a dummy
conversion precedes a real conversion, ADSC will stay high until the real conversion
completes.
Writing a zero to this bit has no effect.
80
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
• Bit 5 – Res: Reserved Bit
This bit is reserved in the ATmega103(L). Warning: When writing ADCSR, a logical “0”
must be written to this bit.
• Bit 4 – ADIF: ADC Interrupt Flag
This bit is set (one) when an ADC conversion is complete and the result is written to the
ADC Data Registers are updated. The ADC Conversion Complete interrupt is executed
if the ADIE bit and the I-bit 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 “1” 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.
• Bits 2..0 – ADPS2..ADPS0: ADC Prescaler Select Bits
These bits determine the division factor between the XTAL frequency and the input
clock to the ADC.
Table 27. ADC Prescaler Selections
ADC Data Register – ADCL
and ADCH
ADPS2
ADPS1
ADPS0
Division Factor
0
0
0
Invalid
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
Bit
15
14
13
12
11
10
9
8
$05 ($25)
–
–
–
–
–
–
ADC9
ADC8
ADCH
$04 ($24)
ADC7
ADC6
ADC5
ADC4
ADC3
ADC2
ADC1
ADC0
ADCL
Read/Write
Initial Value
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
When an ADC conversion is complete, the result is found in these two registers. It is
essential that both registers are read and that ADCL is read before ADCH.
81
0945I–AVR–02/07
ADC Noise Canceling
Techniques
Digital circuitry inside and outside the ATmega103(L) 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 ATmega103(L) 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 ATmega103(L) should have its own decoupling capacitor as
shown in Figure 49.
4. Use the ADC Noise Canceler function to reduce induced noise from the CPU.
5. If some Port F pins are used as digital inputs, it is essential that these do not
switch while a conversion is in progress.
Figure 49. ADC Power Connections
52
GND
53
(ADC7) PF7
54
(ADC6) PF6
55
(ADC5) PF5
56
(ADC4) PF4
57
(ADC3) PF3
58
(ADC2) PF2
59
(ADC1) PF1
60
(ADC0) PF0
61
AREF
62
AGND
AVCC
10nF
Analog Ground Plane
82
51
ATmega103(L)
VCC
63
64
1
PEN
(AD0) PA0
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
ADC DC Characteristics
TA = -40°C to 85°C
Symbol
Parameter
Condition
Min
Resolution
Max
10
Units
Bits
Absolute
accuracy
VREF = 4V, VCC = 4V
ADC clock = 200 kHz
1
Absolute
accuracy
VREF = 4V, VCC = 4V
ADC clock = 1 MHz
4
LSB
Absolute
accuracy
VREF = 4V, VCC = 4V
ADC clock = 2 MHz
16
LSB
Integral
Non-linearity
VREF > 2V
0.5
LSB
Differential
Non-linearity
VREF > 2V
0.5
LSB
1
LSB
Zero Error
(Offset)
2
LSB
Conversion
Time
70
280
µs
Clock
Frequency
50
200
kHz
VCC - 0.3(1)
VCC + 0.3(2)
V
AVCC
V
13
kΩ
AVCC
Analog
Supply
Voltage
VREF
Reference
Voltage
2
RREF
Reference
Input
Resistance
6
RAIN
Analog Input
Resistance
Notes:
Typ
10
100
MΩ
1. Minimum for AVCC is 2.7V.
2. Maximum for AVCC is 6.0V.
83
0945I–AVR–02/07
Interface to External
SRAM
The interface to the SRAM consists of:
Port A: multiplexed low-order address bus and data bus
Port C: high-order address bus
The ALE pin: address latch enable
The RD and WR pin: read and write strobes
The external data SRAM is enabled by setting the external SRAM enable bit (SRE) of
the MCU Control Register (MCUCR) and will override the setting of the Data Direction
Register (DDRA). When the SRE bit is cleared (zero), the external data SRAM is disabled and the normal pin and data direction settings are used. When SRE is cleared
(zero), the address space above the internal SRAM boundary is not mapped into the
internal SRAM as AVR parts do not have an interface to the external SRAM.
When ALE goes from high to low, there is a valid address on Port A. ALE is low during a
data transfer. RD and WR are active when accessing the external SRAM only.
When the external SRAM is enabled, the ALE signal may have short pulses when
accessing the internal RAM, but the ALE signal is stable when accessing the external
SRAM.
Figure 50 shows how to connect an external SRAM to the AVR using eight latches that
are transparent when G is high.
By default, the external SRAM access is a three-cycle scheme as depicted in Figure 51.
When one extra wait state is needed in the access cycle, set the SRW bit (one) in the
MCUCR Register. The resulting access scheme is shown in Figure 52. In both cases,
note that Port A is data bus in one cycle only. As soon as the data access finishes, Port
A becomes a low-order address bus again.
Note:
If a read is followed by a write, or vice versa, there is no extra insertion of wait states in
between. The user may insert a NOP between consecutive read and write operations to
the external RAM, because such short time for releasing the bus is difficult to obtain without making bus contention.
For details on the timing for the SRAM interface, please refer to Figure 79, Table 45,
Table 46, Table 47, and Table 48 in the section “DC Characteristics” on page 118 and
refer to “Architectural Overview” on page 8 for a description of the memory map, including address space for SRAM.
Figure 50. External SRAM Connected to the AVR
D[7:0]
Port A
D
ALE
G
Q
A[7:0]
SRAM
AVR
Port C
84
A[15:8]
RD
RD
WR
WR
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 51. External SRAM Access Cycle without Wait States
T1
T2
T3
System Clock Ø
ALE
Prev. Address
Data / Address [7..0]
Prev. Address
Address
Data
Address
Write
Address [15..8]
Address
Data / Address [7..0]
Prev. Address
Address
Data
Address
Read
WR
RD
Figure 52. External SRAM Access Cycle with Wait State
T1
T2
T3
T4
System Clock Ø
ALE
Data / Address [7..0]
Prev. Address
Address
Address
Data
Addr
.
Write
Prev. Address
Addr
.
Read
Address [15..8]
WR
Data / Address [7..0]
Prev. Address Address
Data
RD
85
0945I–AVR–02/07
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.
The Port A pins have alternate functions related to the optional external data SRAM.
Port A can be configured to be the multiplexed low-order address/data bus during
accesses to the byte.
When Port A is set to the alternate function by the SRE (External SRAM Enable) bit in
the MCUCR (MCU Control Register), the alternate settings override the Data Direction
Register.
Port A Data Register – PORTA
Bit
Port A Data Direction Register
– DDRA
Port A Input Pins Address –
PINA
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; this address enables access to
the physical value on each Port A pin. When reading PORTA the Port A 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 eight pins in Port A have equal functionality 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, PORTAn has to be cleared (zero) or the pin has to be configured as an output pin. The port
86
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
pins are tri-stated when a reset condition becomes active, even if the clock is not
running.
Table 28. DDAn Effects on Port A Pins
DDAn
PORTAn
I/O
Pull-up
0
0
Input
No
Tri-state (high-Z)
0
1
Input
Yes
PAn will source current if ext. pulled low.
1
0
Output
No
Push-pull Zero Output
1
Output
No
Push-pull One Output
1
Note:
Port A Schematics
Comment
n: 7,6...0, pin number
Note that all port pins are synchronized. The synchronization latch is, however, not
shown in the figure.
Figure 53. Port A Schematic Diagrams (Pins PA0 - PA7)
RD
MOS
PULLUP
RESET
Q
R
D
DDAn
C
DATA BUS
WD
RESET
R
Q
D
PORTAn
PAn
C
RL
An
Dn
W
R
SRE
WP
RP
WP:
WD:
RL:
RP:
RD:
SRE:
A:
D:
W:
R:
n:
Port B
WRITE PORTA
WRITE DDRA
READ PORTA LATCH
READ PORTA PIN
READ DDRA
EXT. SRAM ENABLE
ADDRESS
DATA
WRITE
READ
0-7
SRE
R
W
Dn
An
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
87
0945I–AVR–02/07
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 29.
Table 29. Port B Pin Alternate Functions
Port Pin
Alternate Functions
PB0
SS (SPI Slave Select input)
PB1
SCK (SPI Bus Serial Clock)
PB2
MOSI (SPI Bus Master Output/Slave Input)
PB3
MISO (SPI Bus Master Input/Slave Output)
PB4
OC0/PWM0 (Output Compare and PWM Output for Timer/Counter0)
PB5
OC1A/PWM1A (Output Compare and PWM Output A for Timer/Counter1)
PB6
OC1B/PWM1B (Output Compare and PWM Output B for Timer/Counter1)
PB7
OC2/PWM2 (Output Compare and PWM Output for Timer/Counter2)
When the pins are used for the alternate function, the DDRB and PORTB Registers
have to be set according to the alternate function description.
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)
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)
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; this address enables access to
the physical value on each Port B pin. When reading PORTB, the Port B Data Latch is
read and when reading PINB, the logical values present on the pins are read.
Port B as General Digital I/O
All eight pins in Port B have equal functionality 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) or the pin has to be configured as an output pin. The
port pins are tri-stated when a reset condition becomes active, even if the clock is not
running.
88
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Table 30. DDBn Effects on Port B Pins
DDBn
PORTBn
I/O
Pull-up
0
0
Input
No
Tri-state (high-Z)
0
1
Input
Yes
PBn will source current if ext. pulled low
1
0
Output
No
Push-pull Zero Output
1
1
Output
No
Push-pull One Output
Note:
Alternate Functions of Port B
Comment
n: 7,6...0, pin number
The alternate pin configuration is as follows:
• OC2/PWM2, Bit 7
OC2/PWM2, Output Compare output for Timer/Counter2 or PWM output when
Timer/Counter2 is in PWM mode. The pin has to be configured as an output to serve
this function.
• OC1B/PWM1B, Bit 6
OC1B/PWM1B, Output Compare output B for Timer/Counter1 or PWM output B when
Timer/Counter1 is in PWM mode. The pin has to be configured as an output to serve
this function.
• OC1A/PWM1A, Bit 5
OC1A/PWM1A, Output Compare output A for Timer/Counter1 or PWM output A when
Timer/Counter1 is in PWM mode. The pin has to be configured as an output to serve
this function.
• OC0/PWM0, Bit 4
OC0/PWM0, Output Compare output for Timer/Counter0 or PWM output when
Timer/Counter0 is in PWM mode. The pin has to be configured as an output to serve
this function.
• MISO – Port B, Bit 3
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
DDB3. When the SPI is enabled as a Slave, the data direction of this pin is controlled by
DDB3. When the pin is forced to be an input, the pull-up can still be controlled by the
PORTB3 bit. See the description of the SPI port for further details.
• MOSI – Port B, Bit 2
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 DDB2.
When the SPI is enabled as a Master, the data direction of this pin is controlled by
DDB2. When the pin is forced to be an input, the pull-up can still be controlled by the
PORTB2 bit. See the description of the SPI port for further details.
• SCK – Port B, Bit 1
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 DDB1.
When the SPI is enabled as a Master, the data direction of this pin is controlled by
89
0945I–AVR–02/07
DDB1. When the pin is forced to be an input, the pull-up can still be controlled by the
PORTB1 bit. See the description of the SPI port for further details.
• SS – Port B, Bit 0
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 DDB0. 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 DDB0. When the pin is forced to be an input, the pull-up can still be controlled by the PORTB0 bit. See the description of the SPI port for further details.
Port B Schematics
Note that all port pins are synchronized. The synchronization latches are, however, not
shown in the figures.
Figure 54. Port B Schematic Diagram (Pin PB0)
90
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 55. Port B Schematic Diagram (Pin PB1)
Figure 56. Port B Schematic Diagram (Pin PB2)
91
0945I–AVR–02/07
Figure 57. Port B Schematic Diagram (Pin PB3)
Figure 58. Port B Schematic Diagram (Pin PB4)
RD
MOS
PULLUP
RESET
Q
R
D
DDB4
WD
RESET
R
Q
D
PORTB4
PB4
DATA BUS
C
C
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
92
WRITE PORTB
WRITE DDRB
READ PORTB LATCH
READ PORTB PIN
READ DDRB
COM01
COM01
OUTPUT
MODE SELECT
COMP. MATCH 0
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 59. Port B Schematic Diagram (Pins PB5 and PB6)
RD
MOS
PULLUP
RESET
R
Q
D
DDBn
C
DATA BUS
WD
RESET
R
Q
D
PORTBn
PBn
C
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
n:
X:
COM1X0
COM1X1
WRITE PORTB
WRITE DDRB
READ PORTB LATCH
READ PORTB PIN
READ DDRB
5, 6
A, B
OUTPUT
MODE SELECT
COMP. MATCH 1X
Figure 60. Port B Schematic Diagram (Pin PB7)
RD
MOS
PULLUP
RESET
Q
R
D
DDB7
WD
RESET
R
Q
D
PORTB7
PB7
DATA BUS
C
C
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
WRITE PORTB
WRITE DDRB
READ PORTB LATCH
READ PORTB PIN
READ DDRB
COM20
COM21
OUTPUT
MODE SELECT
COMP. MATCH 2
93
0945I–AVR–02/07
Port C
Port C is an 8-bit output port.
The Port C pins have alternate functions related to the optional external data SRAM.
When using the device with external SRAM, Port C outputs the high-order address byte
during accesses to external Data memory. When a reset condition becomes active, the
port pins are not tri-stated, but the pins will assume their initial value after two stable
clock cycles.
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)
Port C Schematics
PORTC
Figure 61. Port C Schematic Diagram (Pins PC0 - PC7)
DATA BUS
The Port C Data Register –
PORTC
RESET
R
Q
D
PORTCn
PCn
C
RL
WP:
RL:
A:
SRE:
n:
WP
WRITE PORTC
READ PORTC LATCH
SRAM ADDRESS
EXTERNAL SRAM ENABLE
0-7
SRE
An
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 the 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 31.
Table 31. Port D Pin Alternate Functions
Port Pin
94
Alternate Function
PD0
INT0 (External Interrupt0 Input)
PD1
INT1 (External Interrupt1 Input)
PD2
INT2 (External Interrupt2 Input)
PD3
INT3 (External Interrupt3 Input)
PD4
IC1 (Timer/Counter1 Input Capture Trigger)
PD6
T1 (Timer/Counter1 Clock Input)
PD7
T2 (Timer/Counter2 Clock Input)
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
When the pins are used for the alternate function, the DDRD and PORTD Registers
have to be set according to the alternate function description.
Port D Data Register – PORTD
Port D Data Direction Register
– DDRD
Port D Input Pins Address –
PIND
Bit
7
6
5
4
3
2
1
0
$12
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
Bit
7
6
5
4
3
2
1
0
$11
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
Bit
7
6
5
4
3
2
1
0
$10
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
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 Port D Data Latch
is read, and when reading PIND, the logical values present on the pins are read.
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) or the pin has to be configured as an output pin. The port pins are tristated when a reset condition becomes active, even if the clock is not running.
Table 32. DDDn Bits on Port D Pins
DDDn
PORTDn
I/O
Pull-up
0
0
Input
No
Tri-state (high-Z)
0
1
Input
Yes
PDn will source current if ext. pulled low.
1
0
Output
No
Push-pull Zero Output
1
1
Output
No
Push-pull One Output
Note:
Alternate Functions of Port D
Comment
n: 7,6...0, pin number
The alternate pin functions of Port D are:
• INT0..INT3 – Port D, Bits 0..3
External Interrupt sources 0 - 3. The PD0 - PD3 pins can serve as external active low
interrupt sources to the MCU. The internal pull-up MOS resistors can be activated as
described above. See the interrupt description for further details, and how to enable the
sources.
95
0945I–AVR–02/07
• IC1 – Port D, Bit 4
IC1, Input Capture pin for Timer/Counter1. When a positive or negative (selectable)
edge is applied to this pin, the contents of Timer/Counter1 is transferred to the
Timer/Counter1 Input Capture Register. The pin has to be configured as an input to
serve this function. See the Timer/Counter1 description on how to operate this function.
The internal pull-up MOS resistor can be activated as described above.
• T1 – Port D, Bit 6
T1, Timer/Counter1 counter source. See the Timer description for further details.
• T2 – Port D, Bit 7
T2, Timer/Counter2 counter source. See the Timer description for further details.
Port D Schematics
Note that all port pins are synchronized. The synchronization latches are, however, not
shown in the figures.
Figure 62. Port D Schematic Diagram (Pins PD0, PD1, PD2 and PD3)
RD
MOS
PULLUP
RESET
Q
R
D
DDDn
WD
RESET
R
Q
D
PORTDn
PDn
DATA BUS
C
C
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
n:
96
WRITE PORTD
WRITE DDRD
READ PORTD LATCH
READ PORTD PIN
READ DDRD
0, 1, 2, 3
INTn
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 63. Port D Schematic Diagram (Pin PD4)
RD
MOS
PULLUP
RESET
Q
R
D
DDD4
C
DATA BUS
WD
RESET
R
Q
D
PORTD4
PD4
C
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
ACIC:
ACO:
WRITE PORTD
WRITE DDRD
READ PORTD LATCH
READ PORTD PIN
READ DDRD
COMPARATOR IC ENABLE
COMPARATOR OUTPUT
0
NOISE CANCELER
EDGE SELECT
ICNC1
ICES1
ICF1
1
ACIC
ACO
Figure 64. Port D Schematic Diagram (Pin PD5)
RD
MOS
PULLUP
RESET
Q
R
D
DDD5
WD
RESET
R
Q
D
PORTD5
PD5
DATA BUS
C
C
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
WRITE PORTD
WRITE DDRD
READ PORTD LATCH
READ PORTD PIN
READ DDRD
97
0945I–AVR–02/07
Figure 65. Port D Schematic Diagram (Pins PD6 and PD7)
RD
MOS
PULLUP
RESET
R
Q
D
DDDn
WD
RESET
R
Q
D
PORTDn
PDn
DATA BUS
C
C
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
n:
m:
WRITE PORTD
WRITE DDRD
READ PORTD LATCH
READ PORTD PIN
READ DDRD
6, 7
1, 2
SENSE CONTROL
CSm2 CSm1
Port E
TIMERm CLOCK
SOURCE MUX
CSm0
Port E is an 8-bit bi-directional I/O port with internal pull-up resistors.
Three I/O memory address locations are allocated for the Port E, one each for the Data
Register – PORTE, $03($23), Data Direction Register – DDRE, $02($22) and the Port E
Input Pins – PINE, $01($21). The Port E Input Pins address is read-only, while the Data
Register and the Data Direction Register are read/write.
The Port E output buffers can sink 20 mA. As inputs, Port E pins that are externally
pulled low will source current if the pull-up resistors are activated.
All Port E pins have alternate functions as shown in Table 33.
Table 33. Port E Pin Alternate Functions
Port Pin
Alternate Function
PE0
PDI/RXD (Programming Data Input or UART Receive Pin)
PE1
PDO/TXD (Programming Data Output or UART Transmit Pin)
PE2
AC+ (Analog Comparator Positive Input)
PE3
AC- (Analog Comparator Negative Input)
PE4
INT4 (External Interrupt4 Input)
PE5
INT5 (External Interrupt5 Input)
PE6
INT6 (External Interrupt6 Input)
PE7
INT7 (External Interrupt7 Input)
When the pins are used for the alternate function, the DDRE and PORTE Registers
have to be set according to the alternate function description.
98
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Port E Data Register – PORTE
Bit
7
6
5
4
3
2
1
0
PORTE7
PORTE6
PORTE5
PORTE4
PORTE3
PORTE2
PORTE1
PORTE0
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
$03 ($23)
Port E Data Direction Register
– DDRE
Bit
7
6
5
4
3
2
1
0
DDE7
DDE6
DDE5
DDE4
DDE3
DDE2
DDE1
DDE0
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
$02 ($22)
Port E Input Pins Address –
PINE
Bit
7
6
5
4
3
2
1
0
PINE7
PINE6
PINE5
PINE4
PINE3
PINE2
PINE1
PINE0
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
$01 ($21)
PORTE
DDRE
PINE
The Port E Input Pins address (PINE) is not a register; this address enables access to
the physical value on each Port E pin. When reading PORTE, the Port E Data Latch is
read and when reading PINE, the logical values present on the pins are read.
Port E as General Digital I/O
PEn, general I/O pin: The DDEn bit in the DDRE Register selects the direction of this
pin. If DDEn is set (one), PEn is configured as an output pin. If DDEn is cleared (zero),
PEn is configured as an input pin. If PEn is set (one) when configured as an input pin,
the MOS pull-up resistor is activated. To switch the pull-up resistor off, the PEn has to
be cleared (zero) or the pin has to be configured as an output pin.The port pins are tristated when a reset condition becomes active, even if the clock is not running.
Table 34. DDEn Bits on Port E Pins
DDEn
PORTEn
I/O
Pull-up
0
0
Input
No
Tri-state (high-Z)
0
1
Input
Yes
PDn will source current if ext. pulled low.
1
0
Output
No
Push-pull Zero Output
1
1
Output
No
Push-pull One Output
Note:
Alternate Functions of Port E
Comment
n: 7,6...0, pin number
The alternate pin functions of Port E are:
• PDI/RXD – Port E, Bit 0
PDI, Serial Programming Data Input. During Serial Program downloading, this pin is
used as data input line for the ATmega103(L).
RXD, UART Receive Pin. 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 “1” in PORTD0 will turn on the
internal pull-up.
• PDO/TXD – Port E, Bit 1
PDO, Serial Programming Data Output. During Serial Program downloading, this pin is
used as data output line for the ATmega103(L).
99
0945I–AVR–02/07
TXD, UART Transmit Pin.
• AC+ – Port E, Bit 2
AC+, Analog Comparator Positive Input. This pin is directly connected to the positive
input of the analog comparator.
• AC- – Port E, Bit 3
AC-, Analog Comparator Negative Input. This pin is directly connected to the negative
input of the analog comparator.
• INT4..INT7 – Port E, Bits 4 - 7
INT4..INT7, External Interrupt sources 4 - 7: The PE4 - PE7 pins can serve as external
interrupt sources to the MCU. Interrupts can be triggered by low level or positive or negative edge on these pins. The internal pull-up MOS resistors can be activated as
described above. See the interrupt description for further details, and how to enable the
sources.
Port E Schematics
Note that all port pins are synchronized. The synchronization latches are, however, not
shown in the figures.
Figure 66. Port E Schematic Diagram (Pin PE0)
100
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 67. Port E Schematic Diagram (Pin PE1)
Figure 68. Port E Schematic Diagram (Pin PE2)
RD
MOS
PULLUP
RESET
Q
D
DDE2
WD
RESET
Q
D
PORTE2
C
PE2
RL
DATA BUS
C
WP
RP
TO COMPARATOR
WP:
WD:
RL:
RP:
RD:
AC+
WRITE PORTE
WRITE DDRE
READ PORTE LATCH
READ PORTE PIN
READ DDRE
101
0945I–AVR–02/07
Figure 69. Port E Schematic Diagram (Pin PE3)
RD
MOS
PULLUP
RESET
Q
D
DDE3
WD
RESET
Q
D
PORTE3
C
PE3
RL
DATA BUS
C
WP
RP
AC-
TO COMPARATOR
WP:
WD:
RL:
RP:
RD:
WRITE PORTE
WRITE DDRE
READ PORTE LATCH
READ PORTE PIN
READ DDRE
Figure 70. Port E Schematic Diagram (Pins PE4, PE5, PE6 and PE7)
RD
MOS
PULLUP
RESET
Q
R
D
DDEn
WD
RESET
R
Q
D
PORTEn
PEn
DATA BUS
C
C
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
n:
WRITE PORTE
WRITE DDRE
READ PORTE LATCH
READ PORTE PIN
READ DDRE
4, 5, 6, 7
SENSE CONTROL
ISCn1
102
INTn
ISCn0
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Port F
Port F is an 8-bit input port.
One I/O memory location is allocated for Port F, the Port F Input Pins – PINF, $00 ($20).
All Port F pins are connected to the analog multiplexer, which further is connected to the
A/D converter. The digital input function of Port F can be used together with the A/D
converter, allowing the user to use some pins of Port F and digital inputs and other as
analog inputs, at the same time.
Port F Input Pins Address –
PINF
Bit
7
6
5
4
3
2
1
0
PINF7
PINF6
PINF5
PINF4
PINF3
PINF2
PINF1
PINF0
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
$00 ($20)
PINF
The Port F Input Pins address (PINF) is not a register; this address enables access to
the physical value on each Port F pin.
Figure 71. Port F Schematic Diagram (Pins PF7 - PF0)
DATA BUS
RP
PFn
TO ADC MUX
RP:
n:
AINn
READ PORTF PIN
0-7
103
0945I–AVR–02/07
Memory
Programming
Program and Data
Memory Lock Bits
The ATmega103(L) MCU provides two Lock bits that can be left unprogrammed (“1”) or
can be programmed (“0”) to obtain the additional features listed in Table 35. The Lock
bits can only be erased to “1” with the Chip Erase command.
Table 35. Lock Bit Protection Modes
Memory Lock Bits
Mode
LB1
LB2
1
1
1
No memory lock features enabled.
2
0
1
Further programming of the Flash and EEPROM is disabled.(1)
3
0
0
Same as mode 2, and verify is also disabled.
Note:
Fuse Bits
Protection Type
1. In Parallel mode, programming of the Fuse bits are also disabled. Program the Fuse
bits before programming the Lock bits.
The ATmega103(L) has four Fuse bits, SPIEN, SUT1..0 and EESAVE.
•
When the SPIEN Fuse is programmed (“0”), Serial Program and Data Downloading
is enabled. Default value is programmed (“0”). The SPIEN Fuse is not accessible in
Serial Programming mode.
•
When EESAVE is programmed, the EEPROM memory is preserved through the
Chip Erase cycle. Default value is unprogrammed (“1”). The EESAVE Fuse bit
cannot be programmed if any of the Lock bits are programmed.
•
SUT1..0 Fuses: Determine the MCU start-up time. See Table 5 on page 27 for
further details. Default value is unprogrammed (“11”), which gives a nominal start-up
time of 16 ms.
The status of the Fuse bits is not affected by Chip Erase.
Signature Bytes
All Atmel microcontrollers have a 3-byte signature code that identifies the device. This
code can be read in both Serial and Parallel mode. The three bytes reside in a separate
address space.
For the ATmega103 they are:
1. $000: $1E (indicates manufactured by Atmel)
2. $001: $97 (indicates 128K bytes Flash memory)
3. $002: $01 (indicates ATmega103 when signature byte $001 is $97)
Programming the Flash
and EEPROM
Atmel’s ATmega103(L) offers 128K bytes of In-System Reprogrammable Flash memory
and 4K bytes of EEPROM Data memory.
The ATmega103(L) is shipped with the On-chip Flash Program and EEPROM Data
memory arrays in the erased state (i.e., contents = $FF) and ready to be programmed.
This device supports a Parallel Programming mode and a Serial Programming mode.
The +12V supplied to the RESET pin in Parallel Programming mode is used for programming enable only, and no current of significance is drawn by this pin. The Serial
Programming mode provides a convenient way to download program and data into the
ATmega103(L) inside the user’s system.
104
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
The Flash Program memory array on the ATmega103(L) is organized as 512 pages of
256 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 in either
Programming mode.
The EEPROM Data memory array on the ATmega103(L) is programmed byte-by-byte in
either Programming mode. An auto-erase cycle is provided within the self-timed
EEPROM write instruction in the Serial Programming mode.
During programming, the supply voltage must be in accordance with Table 36.
Table 36. Supply Voltage during Programming
Part
Serial Programming
Parallel Programming
ATmega103
4.0 - 5.0V
4.0 - 5.0V
ATmega103L
3.2 - 3.6V
3.2 - 5.0V
Parallel Programming
This section describes how to Parallel Program and verify Flash Program memory,
EEPROM Data memory, Lock bits and Fuse bits in the ATmega103(L). Pulses are
assumed to be at least 500 ns unless otherwise noted.
Signal Names
In this section, some pins of the ATmega103(L) are referenced by signal names describing their function during parallel programming (see Figure 72 and Table 37). Pins not
described in Table 37 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 is shown in Table 38.
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
39.
Figure 72. Parallel Programming
ATmega103(L)
VCC
RDY/BSY
PD1
VCC
OE
PD2
PB7 - PB0
WR
PD3
BS1
PD4
XA0
PD5
XA1
PD6
PAGEL
PA0
+12V
DATA
RESET
PD7
XTAL1
GND
105
0945I–AVR–02/07
.
Table 37. 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
BS2
PD7
I
Byte Select 2 (always low)
PAGEL
PA0
I
Program Memory Page Load
DATA
PB7 - 0
I/O
Bi-directional Data Bus (output when OE is low)
Table 38. 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 39. Command Byte Bit Coding
Command Byte
106
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 Lock and Fuse Bits
0000 0010
Read Flash
0000 0011
Read EEPROM
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Enter Programming Mode
The following algorithm puts the device in Parallel Programming mode:
1. Apply supply voltage according to Table 36, between VCC and GND.
2. Set RESET and BS1 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 will erase the Flash and EEPROM memories, and 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 or EEPROM is
reprogrammed.
Load Command “Chip Erase”
1. Set XA1, XA0 to “10”. This enables command loading.
2. Set BS1 to “0”.
3. Set DATA to “1000 0000”. This is the command for Chip Erase.
4. Give XTAL1 a positive pulse. This loads the command.
5. Give WR a tWLWH_CE wide negative pulse to execute Chip Erase. See Table 40 for
tWLWH_CE value. Chip Erase does not generate any activity on the RDY/BSY pin.
Table 40. Minimum WR Pulse Width for Chip Erase
Programming the Flash
Symbol
3.2V
3.6V
4.0V
5.0V
tWLWH_CE
56 ms
43 ms
35 ms
22 ms
The Flash is organized as 512 pages of 256 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 BS1 to “0”. This selects low data.
2. Set XA1, XA0 to “01”. This enables data loading.
3. Set DATA = Data Low Byte ($00 - $FF).
4. Give XTAL1 a positive pulse. This loads the data byte.
D: Latch Data Low Byte.
1. Give PAGEL a positive pulse. This latches the data Low Byte.
(See Figure 73 for signal waveforms.)
107
0945I–AVR–02/07
E: Load Data High Byte.
1. Set BS1 to “1”. This selects high data.
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 High Byte.
F: Latch Data High Byte.
1. Give PAGEL a positive pulse. This latches the data High Byte.
G: Repeat B through F 128 times to fill the page buffer.
H: Load Address High Byte.
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 - $FF).
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/BSY goes low.
2. Wait until RDY/BSY goes high.
(See Figure 74 for signal waveforms.)
J: End Page Programming.
1. Set XA1, XA0 to “10”. This enables command loading.
2. Set DATA = “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 512 times or until all data has been programmed.
Figure 73. Programming the Flash Waveforms
DATA
$10
ADDR. LOW
ADDR. HIGH
DATA LOW
XA1
XA2
BS1
XTAL1
WR
RDY/BSY
RESET +12V
OE
BS2
PAGEL
108
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 74. 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 107 for details on command, address and data loading):
1. A: Load Command “0001 0001”.
2. H: Load Address High Byte ($00 - $0F).
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 RDY/BSY goes high to program the next byte.
(See Figure 75 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 apply to Flash, EEPROM and signature bytes reading.
109
0945I–AVR–02/07
Figure 75. 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 107 for details on command and address loading):
1. A: Load Command “0000 0010”.
2. H: Load Address High Byte ($00 - $FF).
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 107 for details on command and address loading):
1. A: Load Command “0000 0011”.
2. H: Load Address High Byte ($00 - $0F).
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 Bits
The algorithm for programming the Fuse bits is as follows (refer to “Programming the
Flash” on page 107 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 5 = SPIEN Fuse bit
Bit 3 = EESAVE Fuse bit
Bit 2 = always “1”
110
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Bit 1 = SUT1 Fuse bit
Bit 0 = SUT0 Fuse bit
Bit 7, 6, 4, 2 = “1”. These bits are reserved and should be left unprogrammed (“1”).
3. Give WR a tWLWH_PFB wide negative pulse to execute the programming. tWLWH_PFB is
found in Table 41. Programming the Fuse bits does not generate any activity on
the RDY/BSY pin.
Programming the Lock Bits
The algorithm for programming the Lock bits is as follows (refer to “Programming the
Flash” on page 107 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 2 = Lock Bit2
Bit 1 = Lock Bit1
Bit 7 - 3, 0 = “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 107 for details on command loading):
1. A: Load Command “0000 0100”.
2. Set OE to “0”, and BS to “0”. The status of the Fuse bits can now be read at
DATA (“0” means programmed).
Bit 5 = SPIEN Fuse bit
Bit 3 = EESAVE Fuse bit
Bit 1 = SUT1 Fuse bit
Bit 0 = SUT0 Fuse bit
Set OE to “0”, and BS to “1”. The status of the Lock bits can now be read at DATA
(“0” means programmed).
Bit 2 = Lock Bit2
Bit 1 = Lock Bit1
3. Set OE to “1”.
Reading the Signature Bytes
The algorithm for reading the signature bytes is as follows (refer to “Programming the
Flash” on page 107 for details on command and address loading):
1. A: Load Command “0000 1000”.
2. C: Load Address Low Byte ($00 - $02).
Set OE to “0”, and BS to “0”. The selected signature byte can now be read at DATA.
3. Set OE to “1”.
111
0945I–AVR–02/07
Parallel Programming
Characteristics
Figure 76. Parallel Programming Timing
tXLWL
tXHXL
XTAL1
tDVXH
tXLDX
Data & Contol
(DATA, XA0/1, BS1)
tPLBX t BVWL
tBVXH
PAGEL
tRHBX
tPHPL
tPLWL
Write
tWLWH
WR
tWHRL
RDY/BSY
tWLRH
tXLOL
tOHDZ
tOLDV
Read
OE
DATA
Table 41. Parallel Programming Characteristics TA = 25°C ± 10%, VCC = 5V ± 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
tBVXH
BS1 Valid before XTAL1 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
67
ns
tWLWH
WR Pulse Width Low
tWHRL
WR High to RDY/BSY Low(2)
tWLRH
WR Low to RDY/BSY High
(2)
tXLOL
XTAL1 Low to OE Low
tOLDV
OE Low to DATA Valid
tOHDZ
OE High to DATA Tri-stated
tWLWH_CE
WR Pulse Width Low for Chip Erase
tWLWH_PFB
WR Pulse Width Low for Progr. the Fuse Bits
Notes:
112
(1)
Typ
Max
Units
12.5
V
250
µA
20
0.5
0.7
ns
0.9
67
ms
ns
20
ns
20
ns
5
10
15
ms
1.0
1.5
1.8
ms
1. Use tWLWH_CE for Chip Erase and tWLWH_PFB for programming the fuse bits.
2. If tWLWH is held longer than tWLRH, no RDY/BSY pulse will be seen.
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Serial Downloading
Both the Flash and EEPROM memory arrays can be programmed using the serial interface while RESET is pulled to GND, or when PEN is low during Power-on Reset. The
serial interface consists of pins SCK, RXD/PDI (input) and TXD/PDO (output). After
RESET is set low, the Programming Enable instruction needs to be executed first before
program/erase instructions can be executed.
For the EEPROM, an auto-erase cycle is provided within the self-timed Write instruction
and there is no need to first execute the Chip Erase instruction. The Chip Erase instruction 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
$FFFF for Program memory and $0000 to $0FFF for EEPROM memory.
Either an external clock is supplied at pin XTAL1 or a crystal needs to be connected
across pins XTAL1 and XTAL2. The minimum low and high periods for the serial clock
(SCK) input are defined as follows:
Low: > 2 XTAL1 clock cycles
High: > 2 XTAL1 clock cycles
Figure 77. Serial Programming
ATmega103(L)
VCC
VCC
INSTR. IN
DATA OUT
CLOCK IN
PE0 (PD1/RXD)
PE1 (PD0/TXD)
PB1 (SCK)
XTAL1
RESET
GND
Note:
Serial Programming
Algorithm
Instruction in and data out is not using the SPI pins as on other AVR devices. SCK uses
the SPI pin as usual.
When writing serial data to the ATmega103(L), data is sampled by the ATmega
103/103L on the rising edge of SCK. When reading data from the ATmega103(L), data
is clocked on the falling edge of SCK. See Figure 78 for an explanation. To program and
verify the ATmega103(L) in the Serial Programming mode, the following sequence is
recommended (See 4-byte instruction formats in Table 44.):
1. Power-up sequence: Apply power between VCC and GND while RESET and SCK
are set to “0”. The RESET signal must be kept low during the complete serial
programming session. If a crystal is not connected across pins XTAL1 and
XTAL2, apply a clock signal to the XTAL1 pin. In some systems, the programmer
cannot guarantee that SCK is held low during Power-up. In this case, RESET
must be given a positive pulse of at least two XTAL1 cycles duration after SCK
has been set to “0”.
113
0945I–AVR–02/07
As an alternative to using the RESET signal, PEN can be held low during Poweron Reset while SCK is set to “0”. In this case, only the PEN value at Power-on
Reset is important. If a crystal is not connected across pins XTAL1 and XTAL2,
apply a clock signal to the XTAL1 pin. If the programmer cannot guarantee that
SCK is held low during power-up, the PEN method cannot be used. The device
must be powered down in order to commence normal operation when using this
method.
2. Wait for at least 20 ms and enable serial programming by sending the Programming Enable serial instruction to pin PE0(PDI/RXD).
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
instruction. 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 at least (2 x
tWD_FLASH), give RESET a positive pulse of at least two XTAL1 cycles duration
after SCK has been set to “0”, and start over from step 2.
5. The Flash is programmed one page at a time. The memory page is loaded one
byte at a time by supplying the 7 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 9 MSB of the
address. The next page can be written after tWD_FLASH, i.e., writing 256 bytes
takes tWD_FLASH. 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 42.)
7. Any memory location can be verified by using the Read instruction, which
returns the content at the selected address at serial output PE1(PDO/TXD).
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 a crystal is not used). Set
RESET to “1”. Turn VCC power off.
Table 42 shows the actual delays used in this section.
Please note: The MISO pin is not high-Z during serial programming.
Data Polling for the EEPROM
When a new EEPROM byte has been written and is being programmed into the
EEPROM, reading the address location being programmed will first give the value P1
(please refer to Table 43) until the auto-erase is finished, and then the value P2.
At the time the device is ready for a new EEPROM 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 values P1 and P2, so when programming these values, the user will have to wait
for at least the prescribed time tWD_EEPROM (please refer to Table 42) before programming
the next byte. 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 reprogrammed without chip erasing the device.
114
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Data polling is not implemented for the Flash.
Table 42. Minimum Wait Delay before Writing the Next Flash or EEPROM Location
Symbol
3.2V
3.6V
4.0V
5.0V
tWD_FLASH(Note:)
56 ms
43 ms
35 ms
22 ms
tWD_EEPROM
9 ms
7 ms
6 ms
4 ms
Note:
Per page.
Table 43. Read Back Value during EEPROM Polling
Part/Revision
P1
P2
TBD
TBD
TBD
Note:
See Errata sheet for latest information.
115
0945I–AVR–02/07
Table 44. Serial Programming Instruction Set
Instruction Format
Instruction
Byte 1
Byte 2
Byte 3
Byte 4
Programming Enable
1010 1100
0101 0011
xxxx xxxx
xxxx xxxx
Enable serial programming while
RESET is low.
Chip Erase
1010 1100
100x xxxx
xxxx xxxx
xxxx xxxx
Chip erase EEPROM and Flash.
Read Program Memory
0010 H000
aaaa 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
xbbb bbbb
iiii iiii
Write H (high or low) data i to Program
memory page at word address b.
Write Program Memory Page
0100 1100
aaaa aaaa
bxxx xxxx
xxxx xxxx
Write Program memory page at
address a:b.
Read EEPROM Memory
1010 0000
xxxx aaaa
bbbb bbbb
oooo oooo
Read data o from EEPROM memory
at address a:b.
Write EEPROM Memory
1100 0000
xxxx aaaa
bbbb bbbb
iiii iiii
Write data i to EEPROM memory at
address a:b.
Read Lock Bits
0101 1000
xxxx xxxx
xxxx xxxx
xxxx x21x
Read Lock bits. “0” = programmed,
“1” = unprogrammed.
Write Lock Bits
1010 1100
1111 1211
xxxx xxxx
xxxx xxxx
Write Lock bits. Set bits 1,2 = “0” to
Program Lock bits.
Read Fuse Bits
0101 0000
xxxx xxxx
xxxx xxxx
xx5x 6143
Read Fuse bits. “0” = programmed,
“1” = unprogrammed.
Write Fuse Bits
1010 1100
1011 6143
xxxx xxxx
xxxx xxxx
Write Fuse bits. Set bit 6,4,3 = “0” to
program, “1” to unprogram.
Read Signature Byte
0011 0000
xxxx xxxx
xxxx xxbb
oooo oooo
Read signature byte o at address b.
Note:
116
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 = SUT0 Fuse
4 = SUT1 Fuse
5 = SPIEN Fuse
6 = EESAVE Fuse
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 78. Serial Programming Waveforms
SERIAL DATA INPUT
PE0(PDI/RXD)
MSB
LSB
SERIAL DATA OUTPUT
PE1(PDO/TXD)
MSB
LSB
SERIAL CLOCK INPUT
PB1(SCK)
SAMPLE
117
0945I–AVR–02/07
Electrical Characteristics
Absolute Maximum Ratings*
Operating Temperature.................................. -40°C to +105°C
*NOTICE:
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.
Storage Temperature ..................................... -65°C to +150°C
Voltage on Any Pin except RESET
with Respect to Ground ............................... -1.0V to VCC + .5V
Voltage on RESET with Respect to Ground ...-1.0V to + 13.0V
Maximum Operating Voltage ............................................ 6.6V
DC Current per I/O Pin ............................................... 40.0 mA
DC Current VCC and GND........................................ 400.0 mA
DC Characteristics
TA = -40°C to 85°C, VCC = 2.7V to 3.6V and 4.0V to 5.5V (unless otherwise noted)
Symbol
VIL
Parameter
Condition
Input Low Voltage
Min
Except (XTAL)
VIL1
Input Low Voltage
XTAL
VIH
Input High Voltage
Except (XTAL, RESET)
VIH1
VIH2
Input High Voltage
Max
0.3
Units
VCC(1)
V
(1)
0.2 VCC - 0.1
V
0.6 VCC(2)
VCC + 0.5
V
(2)
VCC + 0.5
V
VCC + 0.5
V
0.6
0.5
V
V
0.7 VCC
RESET
(3)
-0.5
-0.5
XTAL
Input High Voltage
Typ
0.85
VCC(2)
VOL
Output Low Voltage
Ports A, B, C, D, E
IOL = 20 mA, VCC = 5V
IOL = 10 mA, VCC = 3V
VOH
Output High Voltage(4)
Ports A, B, C, D, E
IOH = -3 mA, VCC = 5V
IOH = -1.5 mA, VCC = 3V
IIL
Input Leakage
Current I/O Pin
VCC = 6V, Pin Low
(absolute value)
8.0
µA
IIH
Input Leakage
Current I/O Pin
VCC = 6V, Pin High
(absolute value)
8.0
µA
RRST
Reset Pull-up
100
500
kΩ
RI/O
I/O Pin Pull-up
35
120
kΩ
Active 4 MHz, VCC = 3V
5.0
mA
Idle 4 MHz, VCC = 3V
2.0
mA
Power-down , VCC = 3V
WDT Enabled
40.0
µA
Power-down(5), VCC = 3V
WDT Disabled
25.0
µA
Power-save(5), VCC = 3V
WDT Disabled
35.0
µA
4.3
2.2
V
V
(5)
ICC
118
Power Supply Current
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
DC Characteristics (Continued)
TA = -40°C to 85°C, VCC = 2.7V to 3.6V and 4.0V to 5.5V (unless otherwise noted)
Symbol
Parameter
Condition
VACIO
Analog Comp
Input Offset V
VCC = 5V
VIN = VCC/2
IACLK
Analog Comp
Input Leakage A
VCC = 5V
VIN = VCC/2
tACPD
Notes:
1.
2.
3.
4.
5.
Min
-50
Typ
Max
Units
40
mV
50
nA
Analog Comparator
VCC = 2.7V
750
ns
Propagation Delay
VCC = 4.0V
500
“Max” means the highest value where the pin is guaranteed to be read as low.
“Min” means the lowest value where the pin is guaranteed to be read as high.
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 400 mA.
2] The sum of all IOL, for ports A0 - A7, ALE, C3 - C7 should not exceed 100 mA.
3] The sum of all IOL, for ports C0 - C2, RD, WR, D0 - D7, XTAL2 should not exceed 100 mA.
4] The sum of all IOL, for ports B0 - B7, should not exceed 100 mA.
5] The sum of all IOL, for ports E0 - E7, 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.
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 400 mA.
2] The sum of all IOH, for ports A0 - A7, ALE, C3 - C7 should not exceed 100 mA.
3] The sum of all IOH, for ports C0 - C2, RD, WR, D0 - D7, XTAL2 should not exceed 100 mA.
4] The sum of all IOH, for ports B0 - B7, should not exceed 100 mA.
5] The sum of all IOH, for ports E0 - E7, 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.
Minimum VCC for Power-down is 2V.
119
0945I–AVR–02/07
External Data Memory Timing
Table 45. External Data Memory Characteristics, 4.0 - 6.0 Volts, No Wait State
6 MHz Oscillator
0
Symbol
Parameter
1/tCLCL
Oscillator Frequency
Min
Max
Variable Oscillator
Min
0.0
(1)
Max
Unit
6.0
MHz
1
tLHLL
ALE Pulse Width
48.3
0.5 tCLCL - 35.0
ns
2
tAVLL
Address Valid A to ALE Low
43.3
0.5 tCLCL - 40.0(1)
ns
3a
tLLAX_ST
Address Hold after ALE Low,
ST/STD/STS Instructions
77.3
0.5 tCLCL - 10.0(2)
ns
3b
tLLAX_LD
Address Hold after ALE Low,
LD/LDD/LDS Instructions
15.0
15.0
ns
4
tAVLLC
Address Valid C to ALE Low
43.3
0.5 tCLCL - 40.0(1)
ns
5
tAVRL
Address Valid to RD Low
136.7
1.0 tCLCL - 30.0
ns
6
tAVWL
Address Valid to WR Low
215.0
7
tLLWL
ALE Low to WR Low
146.7
8
tLLRL
ALE Low to RD Low
146.7
9
tDVRH
Data Setup to RD High
70.0
10
tRLDV
Read Low to Data Valid
11
tRHDX
Data Hold after RD High
12
tRLRH
RD Pulse Width
(1)
1.5 tCLCL - 35.0
186.7
186.7
1.0 tCLCL - 20.0
(2)
0.5 tCLCL - 20.0
136.7
0.5 tCLCL + 20.0
1.0 tCLCL - 30.0
0.0
0.0
146.7
1.0 tCLCL - 20.0
ns
ns
ns
(2)
53.3
0.5 tCLCL - 30.0
14
tWHDX
Data Hold after WR High
0.0
0.0
15
tDVWH
Data Valid to WR High
146.7
1.0 tCLCL - 20.0
ns
ns
ns
(1)
63.3
ns
ns
Data Setup to WR Low
WR Pulse Width
(2)
ns
tDVWL
tWLWH
1.0 tCLCL + 20.0
70.0
13
16
ns
0.5 tCLCL - 20.0
ns
Table 46. External Data Memory Characteristics, 4.0 - 6.0 Volts, 1 Cycle Wait State
6 MHz Oscillator
Symbol
Parameter
0
1/tCLCL
Oscillator Frequency
10
tRLDV
Read Low to Data Valid
12
tRLRH
RD Pulse Width
313.4
2.0 tCLCL - 20.0
ns
15
tDVWH
Data Valid to WR High
313.4
2.0 tCLCL - 20.0
ns
16
Notes:
120
tWLWH
WR Pulse Width
Min
Max
Variable Oscillator
Min
Max
Unit
0.0
6.0
MHz
2.0 tCLCL - 30.0
ns
303.4
230.0
(2)
1.5 tCLCL - 20.0
ns
1. This assumes 50% clock duty cycle. The half period is actually the high time of the external clock, XTAL1.
2. This assumes 50% clock duty cycle. The half period is actually the low time of the external clock, XTAL1.
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Table 47. External Data Memory Characteristics, 2.7 - 3.6 Volts, No Wait State
4 MHz Oscillator
0
1
Symbol
Parameter
1/tCLCL
Oscillator Frequency
tLHLL
ALE Pulse Width
Min
Variable Oscillator
Max
Min
0.0
65.0
Max
Unit
4.0
MHz
(1)
ns
(1)
ns
0.5 tCLCL - 60.0
2
tAVLL
Address Valid A to ALE Low
75.0
0.5 tCLCL - 50.0
3a
tLLAX_ST
Address Hold after ALE Low,
ST/STD/STS Instructions
125.0
0.5 tCLCL(2)
ns
3b
tLLAX_LD
Address Hold after ALE Low,
LD/LDD/LDS Instructions
15.0
15.0
ns
4
tAVLLC
Address Valid C to ALE Low
60.0
0.5 tCLCL - 65.0(1)
ns
5
tAVRL
Address Valid to RD Low
205.0
1.0 tCLCL - 45.0
ns
(1)
6
tAVWL
Address Valid to WR Low
325.0
7
tLLWL
ALE Low to WR Low
230.0
270.0
1.0 tCLCL - 20.0
1.0 tCLCL + 20.0
ns
8
tLLRL
ALE Low to RD Low
105.0
145.0
0.5 tCLCL - 20.0(2)
0.5 tCLCL + 20.0(2)
ns
9
tDVRH
Data Setup to RD High
115.0
10
tRLDV
Read Low to Data Valid
11
tRHDX
Data Hold after RD High
12
tRLRH
RD Pulse Width
1.5 tCLCL - 65.0
ns
115.0
ns
210.0
1.0 tCLCL - 40.0
0.0
0.0
230.0
1.0 tCLCL - 20.0
ns
ns
ns
(1)
13
tDVWL
Data Setup to WR Low
90.0
0.5 tCLCL - 35.0
ns
14
tWHDX
Data Hold after WR High
0.0
0.0
ns
15
tDVWH
Data Valid to WR High
230.0
1.0 tCLCL - 20.0
ns
16
tWLWH
WR Pulse Width
100.0
0.5 tCLCL - 25.0(2)
ns
Table 48. External Data Memory Characteristics, 2.7 - 3.6 Volts, 1 Cycle Wait State
4 MHz Oscillator
Min
Max
Variable Oscillator
Symbol
Parameter
Min
Max
Unit
0
1/tCLCL
Oscillator Frequency
0.0
4.0
MHz
10
tRLDV
Read Low to Data Valid
2.0 tCLCL - 40.0
ns
12
tRLRH
RD Pulse Width
480.0
2.0 tCLCL - 20.0
ns
15
tDVWH
Data Valid to WR High
480.0
2.0 tCLCL - 20.0
ns
460.0
16 tWLWH
WR Pulse Width
350.0
1.5 tCLCL - 25.0(2)
Notes: 1. This assumes 50% clock duty cycle. The half period is actually the high time of the external clock, XTAL1.
2. This assumes 50% clock duty cycle. The half period is actually the low time of the external clock, XTAL1.
ns
121
0945I–AVR–02/07
Figure 79. External RAM Timing
T1
T2
T3
T4
0
System Clock Ø
1
4
7
Address [15..8] Prev. Address
Address
Data / Address [7..0]
Prev. Address
15
13
Address
Data
3a
WR
16
6
Prev. Address
RD
Address
Addr.
11
3b
Data / Address [7..0]
Addr.
14
Write
2
Read
ALE
Data
5
10
9
8
12
Note: Clock cycle T3 is only present when external SRAM Wait State is enabled.
External Clock Drive
Waveforms
Figure 80. External Clock Drive Waveforms
VIH1
VIL1
Table 49. External Clock Drive
Symbol
Parameter
1/tCLCL
Oscillator Frequency
tCLCL
Clock Period
250.0
167.0
ns
tCHCX
High Time
100.0
67.0
ns
tCLCX
Low Time
100.0
67.0
ns
tCLCH
Rise Time
1.6
0.5
µs
Fall Time
1.6
0.5
µs
tCHCL
Note:
122
VCC = 2.7V to 3.6V
0.0
4.0
VCC = 4.0V to 5.5V
0.0
6.0
Units
MHz
See “External Data Memory Timing” on page 120. for a description of how the duty cycle
influences the timing for the external Data memory.
ATmega103(L)
0945I–AVR–02/07
ATmega103(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 81. Active Supply Current vs. Frequency
ACTIVE SUPPLY CURRENT vs. FREQUENCY
TA = 25˚C
50
Vcc= 6V
45
Vcc= 5.5V
40
Vcc= 5V
I cc(mA)
35
Vcc= 4.5V
30
25
Vcc= 4V
20
Vcc= 3.6V
15
Vcc= 3.3V
Vcc= 3.0V
10
Vcc= 2.7V
5
0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Frequency (MHz)
123
0945I–AVR–02/07
Figure 82. Active Supply Current vs. VCC
ACTIVE SUPPLY CURRENT vs. Vcc
FREQUENCY = 4 MHz
25
20
TA = 25˚C
I cc(mA)
TA = 85˚C
15
10
5
0
2
2.5
3
3.5
4
4.5
5
5.5
6
Vcc(V)
Figure 83. Idle Supply Current vs. Frequency
IDLE SUPPLY CURRENT vs. FREQUENCY
TA = 25˚C
18
Vcc= 6V
16
Vcc= 5.5V
14
Vcc= 5V
I cc(mA)
12
Vcc= 4.5V
10
Vcc= 4V
8
Vcc= 3.6V
6
Vcc= 3.3V
Vcc= 3.0V
4
Vcc= 2.7V
2
0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Frequency (MHz)
124
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 84. Idle Supply Current vs. VCC
IDLE SUPPLY CURRENT vs. Vcc
FREQUENCY = 4 MHz
7
6
TA = 85˚C
5
I cc(mA)
TA = 25˚C
4
3
2
1
0
2
2.5
3
3.5
4
4.5
5
5.5
6
Vcc(V)
Figure 85. Power-down Supply Current vs. VCC
POWER-DOWN SUPPLY CURRENT vs. Vcc
WATCHDOG TIMER DISABLED
70
TA = 85˚C
60
I cc (µA)
50
40
TA = 70˚C
30
20
TA = 45˚C
TA = 25˚C
10
0
2
2.5
3
3.5
4
4.5
5
5.5
6
Vcc(V)
125
0945I–AVR–02/07
Figure 86. Power-down Supply Current vs. VCC
POWER-DOWN SUPPLY CURRENT vs. Vcc
WATCHDOG TIMER ENABLED
250
200
I cc (µA)
TA = 85˚C
150
TA = 25˚C
100
50
0
2
2.5
3
3.5
4
4.5
5
5.5
6
Vcc(V)
Figure 87. Power-save Supply Current vs. VCC
POWER SAVE SUPPLY CURRENT vs. Vcc
WATCHDOG TIMER DISABLED
80
TA = 85˚C
70
60
I cc (µA)
50
40
30
TA = 25˚C
20
10
0
2
2.5
3
3.5
4
4.5
5
5.5
6
Vcc(V)
126
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 88. Analog Comparator Current vs. VCC
ANALOG COMPARATOR CURRENT vs. Vcc
0.9
0.8
0.7
TA = 25˚C
0.6
I cc(mA)
TA = 85˚C
0.5
0.4
0.3
0.2
0.1
0
2
2.5
3
3.5
4
4.5
5
5.5
6
Vcc(V)
Analog comparator offset voltage is measured as absolute offset.
Figure 89. Analog Comparator Offset Voltage vs. Common Mode Voltage
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)
127
0945I–AVR–02/07
Figure 90. Analog Comparator Offset Voltage vs. Common Mode Voltage
ANALOG COMPARATOR OFFSET VOLTAGE vs.
Vcc = 2.7V
COMMON MODE VOLTAGE
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 91. Analog Comparator Input Leakage Current
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)
128
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 92. Watchdog Oscillator Frequency vs. VCC
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 93. Pull-up Resistor Current vs. Input Voltage
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
129
0945I–AVR–02/07
Figure 94. Pull-up Resistor Current vs. Input Voltage
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
VOP (V)
Figure 95. I/O Pin Sink Current vs. Output Voltage
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
2.5
3
VOL (V)
130
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 96. I/O Pin Source Current vs. Output Voltage
I/O PIN SOURCE CURRENT vs. OUTPUT VOLTAGE
Vcc = 5V
20
TA = 25˚C
18
16
TA = 85˚C
14
10
I
OH (mA)
12
8
6
4
2
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
VOH (V)
Figure 97. I/O Pin Sink Current vs. Output Voltage
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)
131
0945I–AVR–02/07
Figure 98. I/O Pin Source Current vs. Output Voltage
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 99. I/O Pin Input Threshold Voltage vs. VCC
I/O PIN INPUT THRESHOLD VOLTAGE vs. Vcc
TA = 25˚C
2.5
Threshold Voltage (V)
2
1.5
1
0.5
0
2.7
4.0
5.0
Vcc
132
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Figure 100. I/O Pin Input Hysteresis vs. VCC
I/O PIN INPUT HYSTERESIS vs. Vcc
TA = 25˚C
0.18
Input Hysteresis (V)
0.16
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
2.7
4.0
5.0
Vcc
133
0945I–AVR–02/07
Register Summary
Address
Name
$3F ($5F)
SREG
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Page
I
T
H
S
V
N
Z
C
page 20
$3E ($5E)
SPH
SP15
SP14
SP13
SP12
SP11
SP10
SP9
SP8
page 21
$3D ($5D)
SPL
SP7
SP6
SP5
SP4
SP3
SP2
SP1
SP0
page 21
$3C ($5C)
XDIV
XDIVEN
XDIV6
XDIV5
XDIV4
XDIV3
XDIV2
XDIV1
XDIV0
page 23
$3B ($5B)
RAMPZ
–
–
–
–
–
–
–
RAMPZ0
page 22
$3A ($5A)
EICR
ISC71
ISC70
ISC61
ISC60
ISC51
ISC50
ISC41
ISC40
page 31
$39 ($59)
EIMSK
INT7
INT6
INT5
INT4
INT3
INT2
INT1
INT0
page 30
$38 ($58)
EIFR
INTF7
INTF6
INTF5
INTF4
–
–
–
–
page 31
$37 ($57)
TIMSK
OCIE2
TOIE2
TICIE1
OCIE1A
OCIE1B
TOIE1
OCIE0
TOIE0
page 33
$36 ($56)
TIFR
OCF2
TOV2
ICF1
OCF1A
OCF1B
TOV1
OCF0
TOV0
page 35
$35 ($55)
MCUCR
SRE
SRW
SE
SM1
SM0
–
–
–
page 22
$34 ($54)
MCUSR
–
–
–
–
–
–
EXTRF
PORF
page 29
$33 ($53)
TCCR0
–
PWM0
COM01
COM00
CTC0
CS02
CS01
CS00
page 41
$32 ($52)
TCNT0
Timer/Counter0 (8-bit)
$31 ($51)
OCR0
Timer/Counter0 Output Compare Register
$30 ($50)
ASSR
–
–
–
–
AS0
page 42
page 43
TCN0UB
OCR0UB
TCR0UB
page 44
$2F ($4F)
TCCR1A
COM1A1
COM1A0
COM1B1
COM1B0
–
–
PWM11
PWM10
page 49
$2E ($4E)
TCCR1B
ICNC1
ICES1
–
–
CTC1
CS12
CS11
CS10
page 50
$2D ($4D)
TCNT1H
Timer/Counter1 – Counter Register High Byte
page 51
$2C ($4C)
TCNT1L
Timer/Counter1 – Counter Register Low Byte
page 51
$2B ($4B)
OCR1AH
Timer/Counter1 – Output Compare Register A High Byte
page 52
$2A ($4A)
OCR1AL
Timer/Counter1 – Output Compare Register A Low Byte
page 52
$29 ($49)
OCR1BH
Timer/Counter1 – Output Compare Register B High Byte
page 52
$28 ($48)
OCR1BL
Timer/Counter1 – Output Compare Register B Low Byte
page 52
$27 ($47)
ICR1H
Timer/Counter1 – Input Capture Register High Byte
page 52
$26 ($46)
ICR1L
Timer/Counter1 – Input Capture Register Low Byte
$25 ($45)
TCCR2
$24 ($44)
TCNT2
Timer/Counter2 (8-bit)
$23 ($43)
OCR2
Timer/Counter2 Output Compare Register
$21 ($47)
WDTCR
–
–
–
WDTOE
WDE
WDP2
WDP1
WDP0
page 55
$1F ($3F)
EEARH
–
–
–
–
EEAR11
EEAR10
EEAR9
EEAR8
page 57
$1E ($3E)
EEARL
EEPROM Address Register L
$1D ($3D)
EEDR
EEPROM Data Register
$1C ($3C)
EECR
–
–
–
–
EERIE
EEMWE
EEWE
EERE
page 57
$1B ($3B)
PORTA
PORTA7
PORTA6
PORTA5
PORTA4
PORTA3
PORTA2
PORTA1
PORTA0
page 86
$1A ($3A)
DDRA
DDA7
DDA6
DDA5
DDA4
DDA3
DDA2
DDA1
DDA0
page 86
$19 ($39)
PINA
PINA7
PINA6
PINA5
PINA4
PINA3
PINA2
PINA1
PINA0
page 86
$18 ($38)
PORTB
PORTB7
PORTB6
PORTB5
PORTB4
PORTB3
PORTB2
PORTB1
PORTB0
page 88
$17 ($37)
DDRB
DDB7
DDB6
DDB5
DDB4
DDB3
DDB2
DDB1
DDB0
page 88
$16 ($36)
PINB
PINB7
PINB6
PINB5
PINB4
PINB3
PINB2
PINB1
PINB0
page 88
$15 ($35)
PORTC
PORTC7
PORTC6
PORTC5
PORTC4
PORTC3
PORTC2
PORTC1
PORTC0
page 94
$12 ($32)
PORTD
PORTD7
PORTD6
PORTD5
PORTD4
PORTD3
PORTD2
PORTD1
PORTD0
page 95
$11 ($31)
DDRD
DDD7
DDD6
DDD5
DDD4
DDD3
DDD2
DDD1
DDD0
page 95
$10 ($30)
PIND
PIND7
PIND6
PIND5
PIND4
PIND3
PIND2
PIND1
PIND0
page 95
$0F ($2F)
SPDR
$0E ($2E)
SPSR
SPIF
WCOL
–
–
–
–
–
–
page 63
$0D ($2D)
SPCR
SPIE
SPE
DORD
MSTR
CPOL
CPHA
SPR1
SPR0
page 62
$0C ($2C)
UDR
$0B ($2B)
USR
RXC
TXC
UDRE
FE
OR
–
–
–
page 70
$0A ($2A)
UCR
RXCIE
TXCIE
UDRIE
RXEN
TXEN
CHR9
RXB8
TXB8
page 71
$09 ($29)
UBRR
$08 ($28)
ACSR
$07 ($27)
–
PWM2
COM21
COM20
CTC2
CS22
page 52
CS21
CS20
page 41
page 42
page 43
page 57
page 57
SPI Data Register
page 65
UART I/O Data Register
page 70
UART Baud Rate Register
page 74
ACD
–
ACO
ACI
ACIE
ACIC
ACIS1
ACIS0
page 75
ADMUX
–
–
–
–
–
MUX2
MUX1
MUX0
page 80
$06 ($26)
ADCSR
ADEN
ADSC
–
ADIF
ADIE
ADPS2
ADPS1
ADPS0
page 80
$05 ($25)
ADCH
–
–
–
–
–
–
ADC9
ADC8
page 81
$04 ($24)
ADCL
ADC7
ADC6
ADC5
ADC4
ADC3
ADC2
ADC1
ADC0
page 81
$03 ($23)
PORTE
PORTE7
PORTE6
PORTE5
PORTE4
PORTE3
PORTE2
PORTE1
PORTE0
page 99
$02 ($22)
DDRE
DDE7
DDE6
DDE5
DDE4
DDE3
DDE2
DDE1
DDE0
page 99
$01 ($21)
PINE
PINE7
PINE6
PINE5
PINE4
PINE3
PINE2
PINE1
PINE0
page 99
$00 ($20)
PINF
PINF7
PINF6
PINF5
PINF4
PINF3
PINF2
PINF1
PINF0
page 103
Note:
134
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 “1” 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.
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Instruction Set Summary
Mnemonic
Operands
Description
Operation
Flags
# Clocks
ARITHMETIC AND LOGIC INSTRUCTIONS
ADD
Rd, Rr
Add Two Registers
Rd ← Rd + Rr
Z,C,N,V,H
ADC
Rd, Rr
Add with Carry Two Registers
Rd ← Rd + Rr + C
Z,C,N,V,H
1
ADIW
Rdl, K
Add Immediate to Word
Rdh:Rdl ← Rdh:Rdl + K
Z,C,N,V,S
2
SUB
Rd, Rr
Subtract Two Registers
Rd ← Rd - Rr
Z,C,N,V,H
1
SUBI
Rd, K
Subtract Constant from Register
Rd ← Rd - K
Z,C,N,V,H
1
SBC
Rd, Rr
Subtract with Carry Two Registers
Rd ← Rd - Rr - C
Z,C,N,V,H
1
SBCI
Rd, K
Subtract with Carry Constant from Reg.
Rd ← Rd - K - C
Z,C,N,V,H
1
SBIW
Rdl, K
Subtract Immediate from Word
Rdh:Rdl ← Rdh:Rdl - K
Z,C,N,V,S
2
1
1
AND
Rd, Rr
Logical AND Registers
Rd ← Rd • Rr
Z,N,V
ANDI
Rd, K
Logical AND Register and Constant
Rd ← Rd • K
Z,N,V
1
OR
Rd, Rr
Logical OR Registers
Rd ← Rd v Rr
Z,N,V
1
ORI
Rd, K
Logical OR Register and Constant
Rd ← Rd v K
Z,N,V
1
EOR
Rd, Rr
Exclusive OR Registers
Rd ← Rd ⊕ Rr
Z,N,V
1
COM
Rd
One’s Complement
Rd ← $FF - Rd
Z,C,N,V
1
NEG
Rd
Two’s Complement
Rd ← $00 - Rd
Z,C,N,V,H
1
SBR
Rd, K
Set Bit(s) in Register
Rd ← Rd v K
Z,N,V
1
CBR
Rd, K
Clear Bit(s) in Register
Rd ← Rd • ($FF - K)
Z,N,V
1
INC
Rd
Increment
Rd ← Rd + 1
Z,N,V
1
DEC
Rd
Decrement
Rd ← Rd - 1
Z,N,V
1
TST
Rd
Test for Zero or Minus
Rd ← Rd • Rd
Z,N,V
1
CLR
Rd
Clear Register
Rd ← Rd ⊕ Rd
Z,N,V
1
SER
Rd
Set Register
Rd ← $FF
None
1
Relative Jump
PC ← PC + k + 1
None
2
Indirect Jump to (Z)
PC ← Z
None
2
None
3
BRANCH INSTRUCTIONS
RJMP
k
IJMP
JMP
k
Direct Jump
PC ← k
RCALL
k
Relative Subroutine Call
PC ← PC + k + 1
None
3
Indirect Call to (Z)
PC ← Z
None
3
ICALL
Direct Subroutine Call
PC ← k
None
4
RET
Subroutine Return
PC ← STACK
None
4
RETI
Interrupt Return
PC ← STACK
I
if (Rd = Rr) PC ← PC + 2 or 3
None
CALL
k
4
CPSE
Rd, Rr
Compare, Skip if Equal
1/2/3
CP
Rd, Rr
Compare
Rd - Rr
Z,N,V,C,H
CPC
Rd, Rr
Compare with Carry
Rd - Rr - C
Z,N,V,C,H
1
CPI
Rd, K
Compare Register with Immediate
Rd - K
Z,N,V,C,H
1
SBRC
Rr, b
Skip if Bit in Register Cleared
if (Rr(b) = 0) PC ← PC + 2 or 3
None
1/2/3
SBRS
Rr, b
Skip if Bit in Register is Set
if (Rr(b) = 1) PC ← PC + 2 or 3
None
1/2/3
SBIC
P, b
Skip if Bit in I/O Register Cleared
if (P(b) = 0) PC ← PC + 2 or 3
None
1/2/3
SBIS
P, b
Skip if Bit in I/O Register is Set
if (P(b) = 1) PC ← PC + 2 or 3
None
1/2/3
BRBS
s, k
Branch if Status Flag Set
if (SREG(s) = 1) then PC ← PC + k + 1
None
1/2
BRBC
s, k
Branch if Status Flag Cleared
if (SREG(s) = 0) then PC ← PC + k + 1
None
1/2
BREQ
k
Branch if Equal
if (Z = 1) then PC ← PC + k + 1
None
1/2
BRNE
k
Branch if Not Equal
if (Z = 0) then PC ← PC + k + 1
None
1/2
BRCS
k
Branch if Carry Set
if (C = 1) then PC ← PC + k + 1
None
1/2
BRCC
k
Branch if Carry Cleared
if (C = 0) then PC ← PC + k + 1
None
1/2
BRSH
k
Branch if Same or Higher
if (C = 0) then PC ← PC + k + 1
None
1/2
BRLO
k
Branch if Lower
if (C = 1) then PC ← PC + k + 1
None
1/2
BRMI
k
Branch if Minus
if (N = 1) then PC ← PC + k + 1
None
1/2
BRPL
k
Branch if Plus
if (N = 0) then PC ← PC + k + 1
None
1/2
BRGE
k
Branch if Greater or Equal, Signed
if (N ⊕ V = 0) then PC ← PC + k + 1
None
1/2
BRLT
k
Branch if Less Than Zero, Signed
if (N ⊕ V = 1) then PC ← PC + k + 1
None
1/2
BRHS
k
Branch if Half-carry Flag Set
if (H = 1) then PC ← PC + k + 1
None
1/2
BRHC
k
Branch if Half-carry Flag Cleared
if (H = 0) then PC ← PC + k + 1
None
1/2
BRTS
k
Branch if T-flag Set
if (T = 1) then PC ← PC + k + 1
None
1/2
BRTC
k
Branch if T-flag Cleared
if (T = 0) then PC ← PC + k + 1
None
1/2
BRVS
k
Branch if Overflow Flag is Set
if (V = 1) then PC ← PC + k + 1
None
1/2
BRVC
k
Branch if Overflow Flag is Cleared
if (V = 0) then PC ← PC + k + 1
None
1/2
BRIE
k
Branch if Interrupt Enabled
if (I = 1) then PC ← PC + k + 1
None
1/2
BRID
k
Branch if Interrupt Disabled
if (I = 0) then PC ← PC + k + 1
None
1/2
1
DATA TRANSFER INSTRUCTIONS
Extended Load Program Memory
R0 ← (Z + RAMPZ)
None
3
MOV
Rd, Rr
Move between Registers
Rd ← Rr
None
1
LDI
Rd, K
Load Immediate
Rd ← K
None
1
ELPM
135
0945I–AVR–02/07
Instruction Set Summary (Continued)
Mnemonic
Operands
Description
Operation
Flags
LD
Rd, X
Load Indirect
Rd ← (X)
None
# Clocks
2
LD
Rd, X+
Load Indirect and Post-increment
Rd ← (X), X ← X + 1
None
2
LD
Rd, -X
Load Indirect and Pre-decrement
X ← X - 1, Rd ← (X)
None
2
LD
Rd, Y
Load Indirect
Rd ← (Y)
None
2
LD
Rd, Y+
Load Indirect and Post-increment
Rd ← (Y), Y ← Y + 1
None
2
LD
Rd, -Y
Load Indirect and Pre-decrement
Y ← Y - 1, Rd ← (Y)
None
2
LDD
Rd, Y+q
Load Indirect with Displacement
Rd ← (Y + q)
None
2
LD
Rd, Z
Load Indirect
Rd ← (Z)
None
2
LD
Rd, Z+
Load Indirect and Post-increment
Rd ← (Z), Z ← Z + 1
None
2
LD
Rd, -Z
Load Indirect and Pre-decrement
Z ← Z - 1, Rd ← (Z)
None
2
LDD
Rd, Z+q
Load Indirect with Displacement
Rd ← (Z + q)
None
2
LDS
Rd, k
Load Direct from SRAM
Rd ← (k)
None
2
ST
X, Rr
Store Indirect
(X) ← Rr
None
2
ST
X+, Rr
Store Indirect and Post-increment
(X) ← Rr, X ← X + 1
None
2
ST
-X, Rr
Store Indirect and Pre-decrement
X ← X - 1, (X) ← Rr
None
2
ST
Y, Rr
Store Indirect
(Y) ← Rr
None
2
ST
Y+, Rr
Store Indirect and Post-increment
(Y) ← Rr, Y ← Y + 1
None
2
ST
-Y, Rr
Store Indirect and Pre-decrement
Y ← Y - 1, (Y) ← Rr
None
2
STD
Y+q, Rr
Store Indirect with Displacement
(Y + q) ← Rr
None
2
ST
Z, Rr
Store Indirect
(Z) ← Rr
None
2
ST
Z+, Rr
Store Indirect and Post-increment
(Z) ← Rr, Z ← Z + 1
None
2
ST
-Z, Rr
Store Indirect and Pre-decrement
Z ← Z - 1, (Z) ← Rr
None
2
STD
Z+q, Rr
Store Indirect with Displacement
(Z + q) ← Rr
None
2
STS
k, Rr
Store Direct to SRAM
(k) ← Rr
None
2
Load Program Memory
R0 ← (Z)
None
3
In Port
Rd ← P
None
1
1
LPM
IN
Rd, P
OUT
P, Rr
Out Port
P ← Rr
None
PUSH
Rr
Push Register on Stack
STACK ← Rr
None
2
POP
Rd
Pop Register from Stack
Rd ← STACK
None
2
BIT AND BIT-TEST INSTRUCTIONS
SBI
P, b
Set Bit in I/O Register
I/O(P,b) ← 1
None
2
CBI
P, b
Clear Bit in I/O Register
I/O(P,b) ← 0
None
2
LSL
Rd
Logical Shift Left
Rd(n+1) ← Rd(n), Rd(0) ← 0
Z,C,N,V
1
LSR
Rd
Logical Shift Right
Rd(n) ← Rd(n+1), Rd(7) ← 0
Z,C,N,V
1
ROL
Rd
Rotate Left through Carry
Rd(0) ← C, Rd(n+1) ← Rd(n), C ← Rd(7)
Z,C,N,V
1
ROR
Rd
Rotate Right through Carry
Rd(7) ← C, Rd(n) ← Rd(n+1), C ← Rd(0)
Z,C,N,V
1
ASR
Rd
Arithmetic Shift Right
Rd(n) ← Rd(n+1), n = 0..6
Z,C,N,V
1
SWAP
Rd
Swap Nibbles
Rd(3..0) ← Rd(7..4), Rd(7..4) ← Rd(3..0)
None
1
BSET
s
Flag Set
SREG(s) ← 1
SREG(s)
1
BCLR
s
Flag Clear
SREG(s) ← 0
SREG(s)
1
BST
Rr, b
Bit Store from Register to T
T ← Rr(b)
T
1
BLD
Rd, b
Bit Load from T to Register
Rd(b) ← T
None
1
SEC
Set Carry
C←1
C
1
CLC
Clear Carry
C←0
C
1
SEN
Set Negative Flag
N←1
N
1
CLN
Clear Negative Flag
N←0
N
1
SEZ
Set Zero Flag
Z←1
Z
1
CLZ
Clear Zero Flag
Z←0
Z
1
SEI
Global Interrupt Enable
I←1
I
1
CLI
Global Interrupt Disable
I←0
I
1
SES
Set Signed Test Flag
S←1
S
1
CLS
Clear Signed Test Flag
S←0
S
1
SEV
Set Two’s Complement Overflow
V←1
V
1
CLV
Clear Two’s Complement Overflow
V←0
V
1
SET
Set T in SREG
T←1
T
1
CLT
Clear T in SREG
T←0
T
1
SEH
Set Half-carry Flag in SREG
H←1
H
1
CLH
Clear Half-carry Flag in SREG
H←0
H
1
NOP
No Operation
None
1
SLEEP
Sleep
(see specific descr. for Sleep function)
None
1
WDR
Watchdog Reset
(see specific descr. for WD Timer)
None
1
136
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Ordering Information
Speed (MHz)
Power Supply
4
2.7 - 3.6V
6
4.0 - 5.5V
Ordering Code
Package
ATmega103L-4AC
64A
Operation Range
Commercial
(0°C to 70°C)
ATmega103L-4AI
64A
Industrial
(-40°C to 85°C)
ATmega103-6AC
64A
Commercial
(0°C to 70°C)
ATmega103-6AI
64A
Industrial
(-40°C to 85°C)
Package Type
64A
64-lead, Thin (1.0 mm) Plastic Gull Wing Quad Flat Package (TQFP)
137
0945I–AVR–02/07
Packaging Information
64A
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 AEB.
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
15.75
16.00
16.25
D1
13.90
14.00
14.10
E
15.75
16.00
16.25
E1
13.90
14.00
14.10
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
138
2325 Orchard Parkway
San Jose, CA 95131
TITLE
64A, 64-lead, 14 x 14 mm Body Size, 1.0 mm Body Thickness,
0.8 mm Lead Pitch, Thin Profile Plastic Quad Flat Package (TQFP)
DRAWING NO. REV.
64A
B
ATmega103(L)
0945I–AVR–02/07
ATmega103(L)
Table of Contents
Features................................................................................................. 1
Pin Configuration .................................................................................................. 2
Description ............................................................................................ 3
Block Diagram ...................................................................................................... 4
Pin Descriptions.................................................................................................... 5
Clock Options ....................................................................................................... 6
Architectural Overview......................................................................... 8
General-purpose Register File.............................................................................. 9
ALU – Arithmetic Logic Unit................................................................................ 10
ISP Flash Program Memory ............................................................................... 10
SRAM Data Memory........................................................................................... 10
Program and Data Addressing Modes................................................................ 12
EEPROM Data Memory...................................................................................... 17
Memory Access Times and Instruction Execution Timing .................................. 17
I/O Memory ......................................................................................................... 18
Reset and Interrupt Handling.............................................................................. 23
Sleep Modes....................................................................................................... 36
Timer/Counters ................................................................................... 38
Timer/Counter Prescalers................................................................................... 38
8-bit Timer/Counters T/C0 and T/C2 .................................................................. 39
16-bit Timer/Counter1......................................................................................... 47
Watchdog Timer.................................................................................. 55
EEPROM Read/Write Access............................................................. 57
Prevent EEPROM Corruption ............................................................................. 59
Serial Peripheral Interface – SPI........................................................ 60
Data Modes ........................................................................................................ 62
UART.................................................................................................... 66
Data Transmission.............................................................................................. 66
Data Reception ................................................................................................... 68
UART Control ..................................................................................................... 70
Analog Comparator ............................................................................ 75
Analog-to-Digital Converter............................................................... 77
Feature list: .........................................................................................................
Operation ............................................................................................................
Prescaling ...........................................................................................................
ADC Noise Canceler Function............................................................................
ADC Noise Canceling Techniques .....................................................................
77
78
78
80
82
i
0945I–AVR–02/07
ADC DC Characteristics ..................................................................................... 83
Interface to External SRAM................................................................ 84
I/O Ports............................................................................................... 86
Port A.................................................................................................................. 86
Port B.................................................................................................................. 87
Port C.................................................................................................................. 94
Port D.................................................................................................................. 94
Port E.................................................................................................................. 98
Port F ................................................................................................................ 103
Memory Programming...................................................................... 104
Program and Data Memory Lock Bits...............................................................
Fuse Bits...........................................................................................................
Signature Bytes ................................................................................................
Programming the Flash and EEPROM.............................................................
Parallel Programming .......................................................................................
Parallel Programming Characteristics ..............................................................
Serial Downloading...........................................................................................
104
104
104
104
105
112
113
Electrical Characteristics................................................................. 118
Absolute Maximum Ratings*.............................................................................
DC Characteristics............................................................................................
External Data Memory Timing ..........................................................................
External Clock Drive Waveforms ......................................................................
118
118
120
122
Typical Characteristics .................................................................... 123
Register Summary ............................................................................ 134
Instruction Set Summary ................................................................. 135
Ordering Information........................................................................ 137
Packaging Information ..................................................................... 138
64A ................................................................................................................... 138
Table of Contents .................................................................................. i
ii
ATmega103(L)
0945I–AVR–02/07
Atmel Corporation
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San Jose, CA 95131, USA
Tel: 1(408) 441-0311
Fax: 1(408) 487-2600
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0945I–AVR–02/07