ATMEL ATTINY13-20SU 8-bit microcontroller with 1k bytes in-system programmable flash Datasheet

Features
• High Performance, Low Power AVR® 8-Bit Microcontroller
• Advanced RISC Architecture
•
•
•
•
•
•
•
•
– 120 Powerful Instructions – Most Single Clock Cycle Execution
– 32 x 8 General Purpose Working Registers
– Fully Static Operation
– Up to 20 MIPS Througput at 20 MHz
High Endurance Non-volatile Memory segments
– 1K Bytes of In-System Self-programmable Flash program memory
– 64 Bytes EEPROM
– 64 Bytes Internal SRAM
– Write/Erase cyles: 10,000 Flash/100,000 EEPROM
– Data retention: 20 years at 85°C/100 years at 25°C (see page 6)
– Programming Lock for Self-Programming Flash & EEPROM Data Security
Peripheral Features
– One 8-bit Timer/Counter with Prescaler and Two PWM Channels
– 4-channel, 10-bit ADC with Internal Voltage Reference
– Programmable Watchdog Timer with Separate On-chip Oscillator
– On-chip Analog Comparator
Special Microcontroller Features
– debugWIRE On-chip Debug System
– In-System Programmable via SPI Port
– External and Internal Interrupt Sources
– Low Power Idle, ADC Noise Reduction, and Power-down Modes
– Enhanced Power-on Reset Circuit
– Programmable Brown-out Detection Circuit
– Internal Calibrated Oscillator
I/O and Packages
– 8-pin PDIP/SOIC: Six Programmable I/O Lines
– 20-pad MLF: Six Programmable I/O Lines
Operating Voltage:
– 1.8 - 5.5V for ATtiny13V
– 2.7 - 5.5V for ATtiny13
Speed Grade
– ATtiny13V: 0 - 4 MHz @ 1.8 - 5.5V, 0 - 10 MHz @ 2.7 - 5.5V
– ATtiny13: 0 - 10 MHz @ 2.7 - 5.5V, 0 - 20 MHz @ 4.5 - 5.5V
Industrial Temperature Range
Low Power Consumption
– Active Mode:
• 1 MHz, 1.8V: 240µA
– Power-down Mode:
• < 0.1µA at 1.8V
8-bit
Microcontroller
with 1K Bytes
In-System
Programmable
Flash
ATtiny13
ATtiny13V
Not recommended for new
designs. Use ATtiny13A.
Rev. 2535I–AVR–05/08
1. Pin Configurations
Figure 1-1.
Pinout ATtiny13/ATtiny13V
8-PDIP/SOIC
(PCINT5/RESET/ADC0/dW) PB5
(PCINT3/CLKI/ADC3) PB3
(PCINT4/ADC2) PB4
GND
1
2
3
4
8
7
6
5
VCC
PB2 (SCK/ADC1/T0/PCINT2)
PB1 (MISO/AIN1/OC0B/INT0/PCINT1)
PB0 (MOSI/AIN0/OC0A/PCINT0)
15
14
13
12
11
6
7
8
9
10
1
2
3
4
5
VCC
PB2 (SCK/ADC1/T0/PCINT2)
DNC
PB1 (MISO/AIN1/OC0B/INT0/PCINT1)
PB0 (MOSI/AIN0/OC0A/PCINT0)
DNC
DNC
GND
DNC
DNC
(PCINT5/RESET/ADC0/dW) PB5
(PCINT3/CLKI/ADC3) PB3
DNC
DNC
(PCINT4/ADC2) PB4
20
19
18
17
16
DNC
DNC
DNC
DNC
DNC
20-QFN/MLF
NOTE: Bottom pad should be soldered to ground.
DNC: Do Not Connect
10-QFN/MLF
(PCINT5/RESET/ADC0/dW) PB5
(PCINT3/CLKI/ADC3) PB3
DNC
(PCINT4/ADC2) PB4
GND
1
2
3
4
5
10
9
8
7
6
VCC
PB2 (SCK/ADC1/T0/PCINT2)
DNC
PB1 (MISO/AIN1/OC0B/INT0/PCINT1)
PB0 (MOSI/AIN0/OC0A/PCINT0)
NOTE: Bottom pad should be soldered to ground.
DNC: Do Not Connect
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ATtiny13
1.1
1.1.1
Pin Descriptions
VCC
Digital supply voltage.
1.1.2
GND
Ground.
1.1.3
Port B (PB5:PB0)
Port B is a 6-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port B output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port B pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port B also serves the functions of various special features of the ATtiny13 as listed on page 54.
1.1.4
RESET
Reset input. A low level on this pin for longer than the minimum pulse length will generate a
reset, even if the clock is not running. The minimum pulse length is given in Table 18-1 on page
115. Shorter pulses are not guaranteed to generate a reset.
The reset pin can also be used as a (weak) I/O pin.
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2. Overview
The ATtiny13 is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC
architecture. By executing powerful instructions in a single clock cycle, the ATtiny13 achieves
throughputs approaching 1 MIPS per MHz allowing the system designer to optimize power consumption versus processing speed.
2.1
Block Diagram
Figure 2-1.
Block Diagram
8-BIT DATABUS
STACK
POINTER
SRAM
VCC
PROGRAM
COUNTER
GND
PROGRAM
FLASH
WATCHDOG
OSCILLATOR
CALIBRATED
INTERNAL
OSCILLATOR
WATCHDOG
TIMER
TIMING AND
CONTROL
MCU CONTROL
REGISTER
MCU STATUS
REGISTER
TIMER/
COUNTER0
INSTRUCTION
REGISTER
INSTRUCTION
DECODER
CONTROL
LINES
GENERAL
PURPOSE
REGISTERS
INTERRUPT
UNIT
X
Y
Z
PROGRAMMING
LOGIC
ALU
DATA
EEPROM
STATUS
REGISTER
ADC /
ANALOG COMPARATOR
DATA REGISTER
PORT B
DATA DIR.
REG.PORT B
PORT B DRIVERS
RESET
CLKI
PB0-PB5
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ATtiny13
The AVR core combines a rich instruction set with 32 general purpose working registers. All 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 ATtiny13 provides the following features: 1K byte of In-System Programmable Flash, 64
bytes EEPROM, 64 bytes SRAM, 6 general purpose I/O lines, 32 general purpose working registers, one 8-bit Timer/Counter with compare modes, Internal and External Interrupts, a 4channel, 10-bit ADC, a programmable Watchdog Timer with internal Oscillator, and three software selectable power saving modes. The Idle mode stops the CPU while allowing the SRAM,
Timer/Counter, ADC, Analog Comparator, and Interrupt system to continue functioning. The
Power-down mode saves the register contents, disabling all chip functions until the next Interrupt or Hardware Reset. The ADC Noise Reduction mode stops the CPU and all I/O modules
except ADC, to minimize switching noise during ADC conversions.
The device is manufactured using Atmel’s high density non-volatile memory technology. The
On-chip ISP Flash allows the Program memory to be re-programmed In-System through an SPI
serial interface, by a conventional non-volatile memory programmer or by an On-chip boot code
running on the AVR core.
The ATtiny13 AVR is supported with a full suite of program and system development tools
including: C Compilers, Macro Assemblers, Program Debugger/Simulators, and Evaluation kits.
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3. About
3.1
Resources
A comprehensive set of drivers, application notes, data sheets and descriptions on development
tools are available for download at http://www.atmel.com/avr.
3.2
Code Examples
This documentation contains simple code examples that briefly show how to use various parts of
the device. These code examples assume that the part specific header file is included before
compilation. Be aware that not all C compiler vendors include bit definitions in the header files
and interrupt handling in C is compiler dependent. Please confirm with the C compiler documentation for more details.
3.3
Data Retention
Reliability Qualification results show that the projected data retention failure rate is much less
than 1 PPM over 20 years at 85°C or 100 years at 25°C.
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ATtiny13
4. CPU Core
This section discusses the AVR core architecture in general. The main function of the CPU core
is to ensure correct program execution. The CPU must therefore be able to access memories,
perform calculations, control peripherals, and handle interrupts.
4.1
Architectural Overview
Figure 4-1.
Block Diagram of the AVR Architecture
Data Bus 8-bit
Flash
Program
Memory
Program
Counter
Status
and Control
32 x 8
General
Purpose
Registrers
Control Lines
Direct Addressing
Instruction
Decoder
Indirect Addressing
Instruction
Register
Interrupt
Unit
Watchdog
Timer
ALU
Analog
Comparator
I/O Module1
Data
SRAM
I/O Module 2
I/O Module n
EEPROM
I/O Lines
In order to maximize performance and parallelism, the AVR uses a Harvard architecture – with
separate memories and buses for program and data. Instructions in the Program memory are
executed with a single level pipelining. 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 Reprogrammable Flash memory.
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The fast-access Register File contains 32 x 8-bit general purpose working registers with a single
clock cycle access time. This allows single-cycle Arithmetic Logic Unit (ALU) operation. In a typical ALU operation, two operands are output from the Register File, the operation is executed,
and the result is stored back in the Register File – in one clock cycle.
Six of the 32 registers can be used as three 16-bit indirect address register pointers for Data
Space addressing – enabling efficient address calculations. One of the these address pointers
can also be used as an address pointer for look up tables in Flash Program memory. These
added function registers are the 16-bit X-, Y-, and Z-register, described later in this section.
The ALU supports arithmetic and logic operations between registers or between a constant and
a register. Single register operations can also be executed in the ALU. After an arithmetic operation, the Status Register is updated to reflect information about the result of the operation.
Program flow is provided by conditional and unconditional jump and call instructions, able to
directly address the whole address space. Most AVR instructions have a single 16-bit word format. Every Program memory address contains a 16- or 32-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 Stack
Pointer (SP) is read/write accessible in the I/O space. The data SRAM can easily be accessed
through the five different addressing modes supported in the AVR architecture.
The memory spaces in the AVR architecture are all linear and regular memory maps.
A flexible interrupt module has its control registers in the I/O space with an additional Global
Interrupt Enable bit in the Status Register. All interrupts have a separate Interrupt Vector in the
Interrupt Vector table. The interrupts have priority in accordance with their Interrupt Vector position. The lower the Interrupt Vector address, the higher the priority.
The I/O memory space contains 64 addresses for CPU peripheral functions as Control Registers, SPI, and other I/O functions. The I/O memory can be accessed directly, or as the Data
Space locations following those of the Register File, 0x20 - 0x5F.
4.2
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, arithmetic operations between general purpose
registers or between a register and an immediate are executed. The ALU operations are divided
into three main categories – arithmetic, logical, and bit-functions. Some implementations of the
architecture also provide a powerful multiplier supporting both signed/unsigned multiplication
and fractional format. See the “Instruction Set” section for a detailed description.
4.3
Status Register
The Status Register contains information about the result of the most recently executed arithmetic instruction. This information can be used for altering program flow in order to perform
conditional operations. Note that the Status Register is updated after all ALU operations, as
specified in the Instruction Set Reference. This will in many cases remove the need for using the
dedicated compare instructions, resulting in faster and more compact code.
The Status Register is not automatically stored when entering an interrupt routine and restored
when returning from an interrupt. This must be handled by software.
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ATtiny13
4.3.1
SREG – Status Register
Bit
7
6
5
4
3
2
1
0
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 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, 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. The I-bit can also be set and cleared by
the application with the SEI and CLI instructions, as described in the instruction set reference.
• Bit 6 – T: Bit Copy Storage
The Bit Copy instructions BLD (Bit LoaD) and BST (Bit STore) use the T-bit as source or destination for the operated bit. A bit from a register in the Register File can be copied into T by the
BST instruction, and a bit in T can be copied into a bit in a register in the Register File by the
BLD instruction.
• Bit 5 – H: Half Carry Flag
The Half Carry Flag H indicates a Half Carry in some arithmetic operations. Half Carry is useful
in BCD arithmetic. See the “Instruction Set Description” for detailed information.
• Bit 4 – S: Sign Bit, S = N ⊕ V
The S-bit is always an exclusive or between the Negative Flag N and the Two’s Complement
Overflow Flag V. See the “Instruction Set Description” for detailed information.
• Bit 3 – V: Two’s Complement Overflow Flag
The Two’s Complement Overflow Flag V supports two’s complement arithmetics. See the
“Instruction Set Description” for detailed information.
• Bit 2 – N: Negative Flag
The Negative Flag N indicates a negative result in an arithmetic or logic operation. See the
“Instruction Set Description” for detailed information.
• Bit 1 – Z: Zero Flag
The Zero Flag Z indicates a zero result in an arithmetic or logic operation. See the “Instruction
Set Description” for detailed information.
• Bit 0 – C: Carry Flag
The Carry Flag C indicates a carry in an arithmetic or logic operation. See the “Instruction Set
Description” for detailed information.
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4.4
General Purpose Register File
The Register File is optimized for the AVR Enhanced RISC instruction set. In order to achieve
the required performance and flexibility, the following input/output schemes are supported by the
Register File:
• One 8-bit output operand and one 8-bit result input
• Two 8-bit output operands and one 8-bit result input
• Two 8-bit output operands and one 16-bit result input
• One 16-bit output operand and one 16-bit result input
Figure 4-2 shows the structure of the 32 general purpose working registers in the CPU.
Figure 4-2.
AVR CPU General Purpose Working Registers
7
0
Addr.
R0
0x00
R1
0x01
R2
0x02
…
R13
0x0D
General
R14
0x0E
Purpose
R15
0x0F
Working
R16
0x10
Registers
R17
0x11
…
R26
0x1A
X-register Low Byte
R27
0x1B
X-register High Byte
R28
0x1C
Y-register Low Byte
R29
0x1D
Y-register High Byte
R30
0x1E
Z-register Low Byte
R31
0x1F
Z-register High Byte
Most of the instructions operating on the Register File have direct access to all registers, and
most of them are single cycle instructions.
As shown in Figure 4-2 on page 10, 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-pointer registers can be set to index any register in
the file.
4.4.1
10
The X-register, Y-register, and Z-register
The registers R26..R31 have some added functions to their general purpose usage. These registers are 16-bit address pointers for indirect addressing of the data space. The three indirect
address registers X, Y, and Z are defined as described in Figure 4-3 on page 11.
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ATtiny13
Figure 4-3.
The X-, Y-, and Z-registers
15
X-register
XH
XL
7
0
R27 (0x1B)
YH
YL
7
0
R29 (0x1D)
Z-register
0
R26 (0x1A)
15
Y-register
0
7
0
7
0
R28 (0x1C)
15
ZH
7
0
ZL
7
R31 (0x1F)
0
0
R30 (0x1E)
In the different addressing modes these address registers have functions as fixed displacement,
automatic increment, and automatic decrement (see the instruction set reference for details).
4.5
Stack Pointer
The Stack is mainly used for storing temporary data, for storing local variables and for storing
return addresses after interrupts and subroutine calls. The Stack Pointer Register always points
to the top of the Stack. Note that the Stack is implemented as growing from higher memory locations to lower memory locations. This implies that a Stack PUSH command decreases the Stack
Pointer.
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 is automaticall defined to the last
address in SRAM during power on reset. The Stack Pointer must be set to point above 0x60.
The Stack Pointer is decremented by one when data is pushed onto the Stack with the PUSH
instruction, and it is decremented by two when the return address is pushed onto the Stack with
subroutine call or interrupt. The Stack Pointer is incremented by one when data is popped from
the Stack with the POP instruction, and it is incremented by two when data is popped from the
Stack with return from subroutine RET or return from interrupt RETI.
The AVR Stack Pointer is implemented as two 8-bit registers in the I/O space. The number of
bits actually used is implementation dependent. Note that the data space in some implementations of the AVR architecture is so small that only SPL is needed. In this case, the SPH Register
will not be present.
4.5.1
SPL - Stack Pointer Low.
Bit
15
14
13
12
11
10
9
8
SP7
SP6
SP5
SP4
SP3
SP2
SP1
SP0
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
Initial Value
1
0
0
1
1
1
1
1
SPL
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4.6
Instruction Execution Timing
This section describes the general access timing concepts for instruction execution. The AVR
CPU is driven by the CPU clock clkCPU, directly generated from the selected clock source for the
chip. No internal clock division is used.
Figure 4-4 on page 12 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 4-4.
The Parallel Instruction Fetches and Instruction Executions
T1
T2
T3
T4
clkCPU
1st Instruction Fetch
1st Instruction Execute
2nd Instruction Fetch
2nd Instruction Execute
3rd Instruction Fetch
3rd Instruction Execute
4th Instruction Fetch
Figure 4-5 on page 12 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 4-5.
Single Cycle ALU Operation
T1
T2
T3
T4
clkCPU
Total Execution Time
Register Operands Fetch
ALU Operation Execute
Result Write Back
4.7
Reset and Interrupt Handling
The AVR provides several different interrupt sources. These interrupts and the separate Reset
Vector each have a separate Program Vector in the Program memory space. All interrupts are
assigned individual enable bits which must be written logic one together with the Global Interrupt
Enable bit in the Status Register in order to enable the interrupt.
The lowest addresses in the Program memory space are by default defined as the Reset and
Interrupt Vectors. The complete list of vectors is shown in “Interrupts” on page 44. The list also
determines the priority levels of the different interrupts. The lower the address the higher is the
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ATtiny13
priority level. RESET has the highest priority, and next is INT0 – the External Interrupt Request
0.
When an interrupt occurs, the Global Interrupt Enable I-bit is cleared and all interrupts are disabled. The user software can write logic one to the I-bit to enable nested interrupts. All enabled
interrupts can then interrupt the current interrupt routine. The I-bit is automatically set when a
Return from Interrupt instruction – RETI – is executed.
There are basically two types of interrupts. The first type is triggered by an event that sets the
Interrupt Flag. For these interrupts, the Program Counter is vectored to the actual Interrupt Vector in order to execute the interrupt handling routine, and hardware clears the corresponding
Interrupt Flag. Interrupt Flags can also be cleared by writing a logic one to the flag bit position(s)
to be cleared. If an interrupt condition occurs while the corresponding interrupt enable bit is
cleared, the Interrupt Flag will be set and remembered until the interrupt is enabled, or the flag is
cleared by software. Similarly, if one or more interrupt conditions occur while the Global Interrupt
Enable bit is cleared, the corresponding Interrupt Flag(s) will be set and remembered until the
Global Interrupt Enable bit is set, and will then be executed by order of priority.
The second type of interrupts will trigger as long as the interrupt condition is present. These
interrupts do not necessarily have Interrupt Flags. If the interrupt condition disappears before the
interrupt is enabled, the interrupt will not be triggered.
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.
Note that the Status Register is not automatically stored when entering an interrupt routine, nor
restored when returning from an interrupt routine. This must be handled by software.
When using the CLI instruction to disable interrupts, the interrupts will be immediately disabled.
No interrupt will be executed after the CLI instruction, even if it occurs simultaneously with the
CLI instruction. The following example shows how this can be used to avoid interrupts during the
timed EEPROM write sequence..
Assembly Code Example
in r16, SREG
cli
; store SREG value
; disable interrupts during timed sequence
sbi EECR, EEMPE
; start EEPROM write
sbi EECR, EEPE
out SREG, r16
; restore SREG value (I-bit)
C Code Example
char cSREG;
cSREG = SREG; /* store SREG value */
/* disable interrupts during timed sequence */
__disable_interrupt();
EECR |= (1<<EEMPE); /* start EEPROM write */
EECR |= (1<<EEPE);
SREG = cSREG; /* restore SREG value (I-bit) */
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When using the SEI instruction to enable interrupts, the instruction following SEI will be executed before any pending interrupts, as shown in this example.
Assembly Code Example
sei
; set Global Interrupt Enable
sleep; enter sleep, waiting for interrupt
; note: will enter sleep before any pending
; interrupt(s)
C Code Example
__enable_interrupt(); /* set Global Interrupt Enable */
__sleep(); /* enter sleep, waiting for interrupt */
/* note: will enter sleep before any pending interrupt(s) */
4.7.1
Interrupt Response Time
The interrupt execution response for all the enabled AVR interrupts is four clock cycles minimum. After four clock cycles the Program Vector address for the actual interrupt handling routine
is executed. During this four clock cycle period, the Program Counter is pushed onto the Stack.
The vector is normally a jump to the interrupt routine, and this jump takes three clock cycles. If
an interrupt occurs during execution of a multi-cycle instruction, this instruction is completed
before the interrupt is served. If an interrupt occurs when the MCU is in sleep mode, the interrupt
execution response time is increased by four clock cycles. This increase comes in addition to the
start-up time from the selected sleep mode.
A return from an interrupt handling routine takes four clock cycles. During these four clock
cycles, the Program Counter (two bytes) is popped back from the Stack, the Stack Pointer is
incremented by two, and the I-bit in SREG is set.
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5. Memories
This section describes the different memories in the ATtiny13. The AVR architecture has two
main memory spaces, the Data memory and the Program memory space. In addition, the
ATtiny13 features an EEPROM Memory for data storage. All three memory spaces are linear
and regular.
5.1
In-System Reprogrammable Flash Program Memory
The ATtiny13 contains 1K byte On-chip In-System Reprogrammable Flash memory for program
storage. Since all AVR instructions are 16 or 32 bits wide, the Flash is organized as 512 x 16.
The Flash memory has an endurance of at least 10,000 write/erase cycles. The ATtiny13 Program Counter (PC) is nine bits wide, thus addressing the 512 Program memory locations.
“Memory Programming” on page 102 contains a detailed description on Flash data serial downloading using the SPI pins.
Constant tables can be allocated within the entire Program memory address space (see the
LPM – Load Program memory instruction description).
Timing diagrams for instruction fetch and execution are presented in “Instruction Execution Timing” on page 12.
Figure 5-1.
Program Memory Map
Program Memory
0x0000
0x01FF
5.2
SRAM Data Memory
Figure 5-2 on page 16 shows how the ATtiny13 SRAM Memory is organized.
The lower 160 Data memory locations address both the Register File, the I/O memory and the
internal data SRAM. The first 32 locations address the Register File, the next 64 locations the
standard I/O memory, and the last 64 locations address the internal data SRAM.
The five different addressing modes for the Data memory cover: Direct, Indirect with Displacement, Indirect, Indirect with Pre-decrement, and Indirect with Post-increment. In the Register
File, registers R26 to R31 feature the indirect addressing pointer registers.
The direct addressing reaches the entire data space.
The Indirect with Displacement mode reaches 63 address locations from the base address given
by the Y- or Z-register.
When using register indirect addressing modes with automatic pre-decrement and post-increment, the address registers X, Y, and Z are decremented or incremented.
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The 32 general purpose working registers, 64 I/O Registers, and the 64 bytes of internal data
SRAM in the ATtiny13 are all accessible through all these addressing modes. The Register File
is described in “General Purpose Register File” on page 10.
Figure 5-2.
Data Memory Map
Data Memory
32 Registers
64 I/O Registers
0x0000 - 0x001F
0x0020 - 0x005F
0x0060
Internal SRAM
(64 x 8)
0x009F
5.2.1
Data Memory Access Times
This section describes the general access timing concepts for internal memory access. The
internal data SRAM access is performed in two clkCPU cycles as described in Figure 5-3.
Figure 5-3.
On-chip Data SRAM Access Cycles
T1
T2
T3
clkCPU
Address
Compute Address
Address valid
Write
Data
WR
Read
Data
RD
Memory Access Instruction
5.3
Next Instruction
EEPROM Data Memory
The ATtiny13 contains 64 bytes of data EEPROM memory. It is organized as a separate data
space, in which single bytes can be read and written. The EEPROM has an endurance of at
least 100,000 write/erase cycles. The access between the EEPROM and the CPU is described
in the following, specifying the EEPROM Address Registers, the EEPROM Data Register, and
the EEPROM Control Register. For a detailed description of Serial data downloading to the
EEPROM, see page 105.
5.3.1
16
EEPROM Read/Write Access
The EEPROM Access Registers are accessible in the I/O space.
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ATtiny13
The write access times for the EEPROM are given in Table 5-1 on page 21. A self-timing function, however, lets the user software detect when the next byte can be written. If the user code
contains instructions that write the EEPROM, some precautions must be taken. In heavily filtered power supplies, VCC is likely to rise or fall slowly on Power-up/down. This causes the
device for some period of time to run at a voltage lower than specified as minimum for the clock
frequency used. See “Preventing EEPROM Corruption” on page 19 for details on how to avoid
problems in these situations.
In order to prevent unintentional EEPROM writes, a specific write procedure must be followed.
Refer to “Atomic Byte Programming” on page 17 and “Split Byte Programming” on page 17 for
details on this.
When the EEPROM is read, the CPU is halted for four clock cycles before the next instruction is
executed. When the EEPROM is written, the CPU is halted for two clock cycles before the next
instruction is executed.
5.3.2
Atomic Byte Programming
Using Atomic Byte Programming is the simplest mode. When writing a byte to the EEPROM, the
user must write the address into the EEARL Register and data into EEDR Register. If the
EEPMn bits are zero, writing EEPE (within four cycles after EEMPE is written) will trigger the
erase/write operation. Both the erase and write cycle are done in one operation and the total
programming time is given in Table 5-1 on page 21. The EEPE bit remains set until the erase
and write operations are completed. While the device is busy with programming, it is not possible to do any other EEPROM operations.
5.3.3
Split Byte Programming
It is possible to split the erase and write cycle in two different operations. This may be useful if
the system requires short access time for some limited period of time (typically if the power supply voltage falls). In order to take advantage of this method, it is required that the locations to be
written have been erased before the write operation. But since the erase and write operations
are split, it is possible to do the erase operations when the system allows doing time-critical
operations (typically after Power-up).
5.3.4
Erase
To erase a byte, the address must be written to EEARL. If the EEPMn bits are 0b01, writing the
EEPE (within four cycles after EEMPE is written) will trigger the erase operation only (programming time is given in Table 5-1 on page 21). The EEPE bit remains set until the erase operation
completes. While the device is busy programming, it is not possible to do any other EEPROM
operations.
5.3.5
Write
To write a location, the user must write the address into EEARL and the data into EEDR. If the
EEPMn bits are 0b10, writing the EEPE (within four cycles after EEMPE is written) will trigger
the write operation only (programming time is given in Table 5-1 on page 21). The EEPE bit
remains set until the write operation completes. If the location to be written has not been erased
before write, the data that is stored must be considered as lost. While the device is busy with
programming, it is not possible to do any other EEPROM operations.
The calibrated Oscillator is used to time the EEPROM accesses. Make sure the Oscillator frequency is within the requirements described in “OSCCAL – Oscillator Calibration Register” on
page 27.
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The following code examples show one assembly and one C function for erase, write, or atomic
write of the EEPROM. The examples assume that interrupts are controlled (e.g., by disabling
interrupts globally) so that no interrupts will occur during execution of these functions.
Assembly Code Example
EEPROM_write:
; Wait for completion of previous write
sbic EECR,EEPE
rjmp EEPROM_write
; Set Programming mode
ldi
r16, (0<<EEPM1)|(0<<EEPM0)
out
EECR, r16
; Set up address (r17) in address register
out EEARL, r17
; Write data (r16) to data register
out EEDR,r16
; Write logical one to EEMPE
sbi EECR,EEMPE
; Start eeprom write by setting EEPE
sbi EECR,EEPE
ret
C Code Example
void EEPROM_write(unsigned char ucAddress, unsigned char ucData)
{
/* Wait for completion of previous write */
while(EECR & (1<<EEPE))
;
/* Set Programming mode */
EECR = (0<<EEPM1)|(0>>EEPM0)
/* Set up address and data registers */
EEARL = ucAddress;
EEDR = ucData;
/* Write logical one to EEMPE */
EECR |= (1<<EEMPE);
/* Start eeprom write by setting EEPE */
EECR |= (1<<EEPE);
}
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ATtiny13
The next code examples show assembly and C functions for reading the EEPROM. The examples assume that interrupts are controlled so that no interrupts will occur during execution of
these functions.
Assembly Code Example
EEPROM_read:
; Wait for completion of previous write
sbic EECR,EEPE
rjmp EEPROM_read
; Set up address (r17) in address register
out EEARL, r17
; Start eeprom read by writing EERE
sbi EECR,EERE
; Read data from data register
in
r16,EEDR
ret
C Code Example
unsigned char EEPROM_read(unsigned char ucAddress)
{
/* Wait for completion of previous write */
while(EECR & (1<<EEPE))
;
/* Set up address register */
EEARL = ucAddress;
/* Start eeprom read by writing EERE */
EECR |= (1<<EERE);
/* Return data from data register */
return EEDR;
}
5.3.6
Preventing 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 EEPROM, and the same design solutions should be applied.
An EEPROM data corruption can be caused by two situations when the voltage is too low. First,
a regular write sequence to the EEPROM requires a minimum voltage to operate correctly. Secondly, the CPU itself can execute instructions incorrectly, if the supply voltage is too low.
EEPROM data corruption can easily be avoided by following this design recommendation:
Keep the AVR RESET active (low) during periods of insufficient power supply voltage. This can
be done by enabling the internal Brown-out Detector (BOD). If the detection level of the internal
BOD does not match the needed detection level, an external low VCC reset protection circuit can
be used. If a reset occurs while a write operation is in progress, the write operation will be completed provided that the power supply voltage is sufficient.
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5.4
I/O Memory
The I/O space definition of the ATtiny13 is shown in “Register Summary” on page 156.
All ATtiny13 I/Os and peripherals are placed in the I/O space. All I/O locations may be accessed
by the LD/LDS/LDD and ST/STS/STD instructions, transferring data between the 32 general
purpose working registers and the I/O space. I/O Registers within the address range 0x00 0x1F 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 section for more details. When using the I/O specific commands IN and OUT, the I/O
addresses 0x00 - 0x3F must be used. When addressing I/O Registers as data space using LD
and ST instructions, 0x20 must be added to these addresses.
For compatibility with future devices, reserved bits should be written to zero if accessed.
Reserved I/O memory addresses should never be written.
Some of the Status Flags are cleared by writing a logical one to them. Note that, unlike most
other AVRs, the CBI and SBI instructions will only operate on the specified bit, and can therefore
be used on registers containing such Status Flags. The CBI and SBI instructions work with registers 0x00 to 0x1F only.
The I/O and Peripherals Control Registers are explained in later sections.
5.5
5.5.1
Register Description
EEARL – EEPROM Address Register
Bit
7
6
5
4
3
2
1
0
–
–
EEAR5
EEAR4
EEAR3
EEAR2
EEAR1
EEAR0
Read/Write
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
X
X
X
X
X
X
EEARL
• Bits 7:6 – Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and will always read as zero.
• Bits 5:0 – EEAR[5:0]: EEPROM Address
The EEPROM Address Register – EEARL – specifies the EEPROM address in the 64 bytes
EEPROM space. The EEPROM data bytes are addressed linearly between 0 and 63. The initial
value of EEARL is undefined. A proper value must be written before the EEPROM may be
accessed.
5.5.2
EEDR – EEPROM Data Register
Bit
7
6
5
4
3
2
1
0
EEDR7
EEDR6
EEDR5
EEDR4
EEDR3
EEDR2
EEDR1
EEDR0
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
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 EEARL Register. For the EEPROM read operation, the
EEDR contains the data read out from the EEPROM at the address given by EEARL.
20
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ATtiny13
5.5.3
EECR – EEPROM Control Register
Bit
7
6
5
4
3
2
1
0
–
–
EEPM1
EEPM0
EERIE
EEMPE
EEPE
EERE
Read/Write
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
X
X
0
0
X
0
EECR
• Bit 7 – Res: Reserved Bit
This bit is reserved for future use and will always read as 0 in ATtiny13. For compatibility with
future AVR devices, always write this bit to zero. After reading, mask out this bit.
• Bit 6 – Res: Reserved Bit
This bit is reserved in the ATtiny13 and will always read as zero.
• Bits 5:4 – EEPM[1:0]: EEPROM Programming Mode Bits
The EEPROM Programming mode bits setting defines which programming action that will be
triggered when writing EEPE. It is possible to program data in one atomic operation (erase the
old value and program the new value) or to split the Erase and Write operations in two different
operations. The Programming times for the different modes are shown in Table 5-1 on page 21.
While EEPE is set, any write to EEPMn will be ignored. During reset, the EEPMn bits will be
reset to 0b00 unless the EEPROM is busy programming.
Table 5-1.
EEPROM Mode Bits
EEPM1
EEPM0
Programming
Time
0
0
3.4 ms
Erase and Write in one operation (Atomic Operation)
0
1
1.8 ms
Erase Only
1
0
1.8 ms
Write Only
1
1
–
Operation
Reserved for future use
• Bit 3 – EERIE: EEPROM Ready Interrupt Enable
Writing EERIE to one enables the EEPROM Ready Interrupt if the I-bit in SREG is set. Writing
EERIE to zero disables the interrupt. The EEPROM Ready Interrupt generates a constant interrupt when Non-volatile memory is ready for programming.
• Bit 2 – EEMPE: EEPROM Master Program Enable
The EEMPE bit determines whether writing EEPE to one will have effect or not.
When EEMPE is set, setting EEPE within four clock cycles will program the EEPROM at the
selected address. If EEMPE is zero, setting EEPE will have no effect. When EEMPE has been
written to one by software, hardware clears the bit to zero after four clock cycles.
• Bit 1 – EEPE: EEPROM Program Enable
The EEPROM Program Enable Signal EEPE is the programming enable signal to the EEPROM.
When EEPE is written, the EEPROM will be programmed according to the EEPMn bits setting.
The EEMPE bit must be written to one before a logical one is written to EEPE, otherwise no
EEPROM write takes place. When the write access time has elapsed, the EEPE bit is cleared by
hardware. When EEPE has been set, the CPU is halted for two cycles before the next instruction
is executed.
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• 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 EEARL Register, the EERE bit must be written to one to trigger the
EEPROM read. The EEPROM read access takes one instruction, and the requested data is
available immediately. When the EEPROM is read, the CPU is halted for four cycles before the
next instruction is executed. The user should poll the EEPE bit before starting the read operation. If a write operation is in progress, it is neither possible to read the EEPROM, nor to change
the EEARL Register.
22
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6. System Clock and Clock Options
6.1
Clock Systems and their Distribution
Figure 6-1 presents the principal clock systems in the AVR and their distribution. All of the clocks
need not be active at a given time. In order to reduce power consumption, the clocks to modules
not being used can be halted by using different sleep modes, as described in “Power Management and Sleep Modes” on page 30. The clock systems are detailed below.
Figure 6-1.
Clock Distribution
General I/O
Modules
ADC
clkI/O
clkADC
CPU Core
RAM
Flash and
EEPROM
clkCPU
AVR Clock
Control Unit
clkFLASH
Reset Logic
Source clock
Clock
Multiplexer
External Clock
Watchdog Timer
Watchdog clock
Watchdog
Oscillator
Calibrated RC
Oscillator
6.1.1
CPU Clock – clkCPU
The CPU clock is routed to parts of the system concerned with operation of the AVR core.
Examples of such modules are the General Purpose Register File, the Status Register and the
Data memory holding the Stack Pointer. Halting the CPU clock inhibits the core from performing
general operations and calculations.
6.1.2
I/O Clock – clkI/O
The I/O clock is used by the majority of the I/O modules, like Timer/Counter. The I/O clock is
also used by the External Interrupt module, but note that some external interrupts are detected
by asynchronous logic, allowing such interrupts to be detected even if the I/O clock is halted.
6.1.3
Flash Clock – clkFLASH
The Flash clock controls operation of the Flash interface. The Flash clock is usually active simultaneously with the CPU clock.
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6.1.4
6.2
ADC Clock – clkADC
The ADC is provided with a dedicated clock domain. This allows halting the CPU and I/O clocks
in order to reduce noise generated by digital circuitry. This gives more accurate ADC conversion
results.
Clock Sources
The device has the following clock source options, selectable by Flash fuse bits as shown
below. The clock from the selected source is input to the AVR clock generator, and routed to the
appropriate modules.
Table 6-1.
Device Clocking Options Select
CKSEL1:0(1)
Device Clocking Option
External Clock (see page 24)
00
Calibrated Internal 4.8/9.6 MHz Oscillator (see page 25)
01, 10
Internal 128 kHz Oscillator (see page 26)
Note:
11
1. For all fuses “1” means unprogrammed while “0” means programmed.
The various choices for each clocking option is given in the following sections. When the CPU
wakes up from Power-down or Power-save, the selected clock source is used to time the startup, ensuring stable Oscillator operation before instruction execution starts. When the CPU starts
from reset, there is an additional delay allowing the power to reach a stable level before commencing normal operation. The Watchdog Oscillator is used for timing this real-time part of the
start-up time. The number of WDT Oscillator cycles used for each time-out is shown in Table 62.
Table 6-2.
6.2.1
Number of Watchdog Oscillator Cycles
Typ Time-out
Number of Cycles
4 ms
512
64 ms
8K (8,192)
External Clock
To drive the device from an external clock source, CLKI should be driven as shown in Figure 62. To run the device on an external clock, the CKSEL fuses must be programmed to “00”.
Figure 6-2.
External Clock Drive Configuration
EXTERNAL
CLOCK
SIGNAL
CLKI
GND
24
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ATtiny13
When this clock source is selected, start-up times are determined by the SUT fuses as shown in
Table 6-3.
Table 6-3.
Start-up Times for the External Clock Selection
SUT1..0
Start-up Time from
Power-down and Power-save
Additional Delay
from Reset
00
6 CK
14CK
01
6 CK
14CK + 4 ms
Fast rising power
10
6 CK
14CK + 64 ms
Slowly rising power
11
Recommended
Usage
BOD enabled
Reserved
When applying an external clock, it is required to avoid sudden changes in the applied clock frequency to ensure stable operation of the MCU. A variation in frequency of more than 2% from
one clock cycle to the next can lead to unpredictable behavior. It is required to ensure that the
MCU is kept in Reset during such changes in the clock frequency.
Note that the System Clock Prescaler can be used to implement run-time changes of the internal
clock frequency while still ensuring stable operation. Refer to “System Clock Prescaler” on page
26 for details.
6.2.2
Calibrated Internal 4.8/9.6 MHz Oscillator
The calibrated internal oscillator provides a 4.8 or 9.6 MHz clock source. The frequency is nominal at 3V and 25°C. If the frequency exceeds the specification of the device (depends on VCC),
the CKDIV8 fuse must be programmed so that the internal clock is divided by 8 during start-up.
See “System Clock Prescaler” on page 26. for more details.
The internal oscillator is selected as the system clock by programming the CKSEL fuses as
shown in Table 6-4. If selected, it will operate with no external components.
Table 6-4.
Internal Calibrated RC Oscillator Operating Modes
CKSEL1..0
(1)
10
01
Note:
Nominal Frequency
9.6 MHz
4.8 MHz
1. The device is shipped with this option selected.
During reset, hardware loads the calibration data into the OSCCAL register and thereby automatically calibrates the oscillator. There are separate calibration bytes for 4.8 and 9.6 MHz
operation but only one is automatically loaded during reset (see section “Calibration Bytes” on
page 104). This is because the only difference between 4.8 MHz and 9.6 MHz mode is an internal clock divider.
By changing the OSCCAL register from SW, see “OSCCAL – Oscillator Calibration Register” on
page 27, it is possible to get a higher calibration accuracy than by using the factory calibration.
See “Calibrated Internal RC Oscillator Accuracy” on page 118.
When this oscillator is used as the chip clock, the Watchdog Oscillator will still be used for the
Watchdog Timer and for the Reset Time-out. For more information on the pre-programmed calibration value, see the section “Calibration Bytes” on page 104.
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When this Oscillator is selected, start-up times are determined by the SUT fuses as shown in
Table 6-5.
Table 6-5.
Start-up Times for the Internal Calibrated RC Oscillator Clock Selection
SUT1..0
Start-up Time
from Power-down
Additional Delay from
Reset (VCC = 5.0V)
00
6 CK
14CK
01
6 CK
14CK + 4 ms
Fast rising power
6 CK
14CK + 64 ms
Slowly rising power
(1)
10
11
Note:
6.2.3
Recommended Usage
BOD enabled
Reserved
1. The device is shipped with this option selected.
Internal 128 kHz Oscillator
The 128 kHz internal Oscillator is a low power Oscillator providing a clock of 128 kHz. The frequency depends on supply voltage, temperature and batch variations. This clock may be select
as the system clock by programming the CKSEL fuses to “11”.
When this clock source is selected, start-up times are determined by the SUT fuses as shown in
Table 6-6.
Table 6-6.
SUT1:0
Start-up Time from
Power-down and Power-save
Additional Delay
from Reset
00
6 CK
14CK
01
6 CK
14CK + 4 ms
Fast rising power
10
6 CK
14CK + 64 ms
Slowly rising power
11
6.2.4
6.3
Start-up Times for the 128 kHz Internal Oscillator
Recommended
Usage
BOD enabled
Reserved
Default Clock Source
The device is shipped with CKSEL = “10”, SUT = “10”, and CKDIV8 programmed. The default
clock source setting is therefore the Internal RC Oscillator running at 9.6 MHz with longest startup time and an initial system clock prescaling of 8. This default setting ensures that all users can
make their desired clock source setting using an In-System or High-voltage Programmer.
System Clock Prescaler
The ATtiny13 system clock can be divided by setting the “CLKPR – Clock Prescale Register” on
page 28. This feature can be used to decrease power consumption when the requirement for
processing power is low. This can be used with all clock source options, and it will affect the
clock frequency of the CPU and all synchronous peripherals. clkI/O, clkADC, clkCPU, and clkFLASH
are divided by a factor as shown in Table 6-8 on page 28.
6.3.1
26
Switching Time
When switching between prescaler settings, the System Clock Prescaler ensures that no
glitches occur in the clock system and that no intermediate frequency is higher than neither the
clock frequency corresponding to the previous setting, nor the clock frequency corresponding to
the new setting.
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ATtiny13
The ripple counter that implements the prescaler runs at the frequency of the undivided clock,
which may be faster than the CPU’s clock frequency. Hence, it is not possible to determine the
state of the prescaler – even if it were readable, and the exact time it takes to switch from one
clock division to another cannot be exactly predicted.
From the time the CLKPS values are written, it takes between T1 + T2 and T1 + 2*T2 before the
new clock frequency is active. In this interval, 2 active clock edges are produced. Here, T1 is the
previous clock period, and T2 is the period corresponding to the new prescaler setting.
6.4
6.4.1
Register Description
OSCCAL – Oscillator Calibration Register
Bit
7
6
5
4
3
2
1
0
–
CAL6
CAL5
CAL4
CAL3
CAL2
CAL1
CAL0
Read/Write
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
OSCCAL
Device Specific Calibration Value
• Bit 7 – Res: Reserved Bit
This bit is reserved bit in ATtiny13 and it will always read zero.
• Bits 6:0 – CAL[6:0]: Oscillator Calibration Value
Writing the calibration byte to this address will trim the internal Oscillator to remove process variations from the Oscillator frequency. This is done automatically during Chip Reset. When
OSCCAL is zero, the lowest available frequency is chosen. Writing non-zero values to this register will increase the frequency of the internal Oscillator. Writing 0x7F to the register gives the
highest available frequency.
The calibrated Oscillator is used to time EEPROM and Flash access. If EEPROM or Flash is
written, do not calibrate to more than 10% above the nominal frequency. Otherwise, the
EEPROM or Flash write may fail. Note that the Oscillator is intended for calibration to 9.6 MHz or
4.8 MHz. Tuning to other values is not guaranteed, as indicated in Table 6-7 below.
To ensure stable operation of the MCU the calibration value should be changed in small steps. A
variation in frequency of more than 2% from one cycle to the next can lead to unpredicatble
behavior. Changes in OSCCAL should not exceed 0x20 for each calibration. It is required to
ensure that the MCU is kept in Reset during such changes in the clock frequency
Table 6-7.
Internal RC Oscillator Frequency Range
OSCCAL Value
Typical Lowest Frequency
with Respect to Nominal Frequency
Typical Highest Frequency
with Respect to Nominal Frequency
0x00
50%
100%
0x3F
75%
150%
0x7F
100%
200%
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6.4.2
CLKPR – Clock Prescale Register
Bit
7
6
5
4
3
2
1
0
CLKPCE
–
–
–
CLKPS3
CLKPS2
CLKPS1
CLKPS0
Read/Write
R/W
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
CLKPR
See Bit Description
• Bit 7 – CLKPCE: Clock Prescaler Change Enable
The CLKPCE bit must be written to logic one to enable change of the CLKPS bits. The CLKPCE
bit is only updated when the other bits in CLKPR are simultaneously written to zero. CLKPCE is
cleared by hardware four cycles after it is written or when the CLKPS bits are written. Rewriting
the CLKPCE bit within this time-out period does neither extend the time-out period, nor clear the
CLKPCE bit.
• Bits 6:4 – Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and will always read as zero.
• Bits 3:0 – CLKPS3:0: Clock Prescaler Select Bits 3 - 0
These bits define the division factor between the selected clock source and the internal system
clock. These bits can be written run-time to vary the clock frequency to suit the application
requirements. As the divider divides the master clock input to the MCU, the speed of all synchronous peripherals is reduced when a division factor is used. The division factors are given in
Table 6-8 on page 28.
To avoid unintentional changes of clock frequency, a special write procedure must be followed
to change the CLKPS bits:
1. Write the Clock Prescaler Change Enable (CLKPCE) bit to one and all other bits in
CLKPR to zero.
2. Within four cycles, write the desired value to CLKPS while writing a zero to CLKPCE.
Interrupts must be disabled when changing prescaler setting to make sure the write procedure is
not interrupted.hee setting. The Application software must ensure that a sufficient division factor
is chosen if the selected clock source has a higher frequency than the maximum frequency of
the device at the present operating conditions. The device is shipped with the CKDIV8 fuse
programmed.
Table 6-8.
28
Clock Prescaler Select
CLKPS3
CLKPS2
CLKPS1
CLKPS0
Clock Division Factor
0
0
0
0
1
0
0
0
1
2
0
0
1
0
4
0
0
1
1
8
0
1
0
0
16
0
1
0
1
32
0
1
1
0
64
0
1
1
1
128
1
0
0
0
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ATtiny13
Table 6-8.
Clock Prescaler Select (Continued)
CLKPS3
CLKPS2
CLKPS1
CLKPS0
Clock Division Factor
1
0
0
1
Reserved
1
0
1
0
Reserved
1
0
1
1
Reserved
1
1
0
0
Reserved
1
1
0
1
Reserved
1
1
1
0
Reserved
1
1
1
1
Reserved
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7. Power Management and Sleep Modes
The high performance and industry leading code efficiency makes the AVR microcontrollers an
ideal choise for low power applications. In addition, sleep modes enable the application to shut
down unused modules in the MCU, thereby saving power. The AVR provides various sleep
modes allowing the user to tailor the power consumption to the application’s requirements.
7.1
Sleep Modes
Figure 6-1 on page 23 presents the different clock systems in the ATtiny13, and their distribution. The figure is helpful in selecting an appropriate sleep mode. Table 7-1 shows the different
sleep modes and their wake up sources.
Table 7-1.
Active Clock Domains and Wake-up Sources in the Different Sleep Modes
clkADC
Main Clock
Source Enabled
INT0 and
Pin Change
SPM/
EEPROM
Ready
ADC
Other I/O
Watchdog
Interrupt
Wake-up Sources
X
X
X
X
X
X
X
X
X
X
X(1)
X
X
ADC Noise
Reduction
Power-down
Note:
Oscillators
clkIO
Idle
clkFLASH
Sleep Mode
clkCPU
Active Clock Domains
X(1)
X
X
1. For INT0, only level interrupt.
To enter any of the three sleep modes, the SE bit in MCUCR must be written to logic one and a
SLEEP instruction must be executed. The SM1..0 bits in the MCUCR Register select which
sleep mode (Idle, ADC Noise Reduction, or Power-down) will be activated by the SLEEP instruction. See Table 7-2 on page 33 for a summary.
If an enabled interrupt occurs while the MCU is in a sleep mode, the MCU wakes up. The MCU
is then halted for four cycles in addition to the start-up time, executes the interrupt routine, and
resumes execution from the instruction following SLEEP. The contents of the Register File and
SRAM are unaltered when the device wakes up from sleep. If a reset occurs during sleep mode,
the MCU wakes up and executes from the Reset Vector.
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. Refer to “External Interrupts” on page 45
for details.
7.1.1
Idle Mode
When the SM[1:0] bits are written to 00, the SLEEP instruction makes the MCU enter Idle mode,
stopping the CPU but allowing Analog Comparator, ADC, Timer/Counter, Watchdog, and the
interrupt system to continue operating. This sleep mode basically halts clkCPU and clkFLASH, while
allowing the other clocks to run.
Idle mode enables the MCU to wake up from external triggered interrupts as well as internal
ones like the Timer Overflow. 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
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ATtiny13
Control and Status Register – ACSR. This will reduce power consumption in Idle mode. If the
ADC is enabled, a conversion starts automatically when this mode is entered.
7.1.2
ADC Noise Reduction Mode
When the SM[1:0] bits are written to 01, the SLEEP instruction makes the MCU enter ADC
Noise Reduction mode, stopping the CPU but allowing the ADC, the external interrupts, and the
Watchdog to continue operating (if enabled). This sleep mode halts clkI/O, clkCPU, and clkFLASH,
while allowing the other clocks to run.
This improves the noise environment for the ADC, enabling higher resolution measurements. If
the ADC is enabled, a conversion starts automatically when this mode is entered. Apart form the
ADC Conversion Complete interrupt, only an External Reset, a Watchdog Reset, a Brown-out
Reset, an SPM/EEPROM ready interrupt, an external level interrupt on INT0 or a pin change
interrupt can wake up the MCU from ADC Noise Reduction mode.
7.1.3
7.2
Power-down Mode
When the SM[1:0] bits are written to 10, the SLEEP instruction makes the MCU enter Powerdown mode. In this mode, the Oscillator is stopped, while the external interrupts, and the Watchdog continue operating (if enabled). Only an External Reset, a Watchdog Reset, a Brown-out
Reset, an external level interrupt on INT0, or a pin change interrupt can wake up the MCU. This
sleep mode halts all generated clocks, allowing operation of asynchronous modules only.
Minimizing Power Consumption
There are several issues to consider when trying to minimize the power consumption in an AVR
controlled system. In general, sleep modes should be used as much as possible, and the sleep
mode should be selected so that as few as possible of the device’s functions are operating. All
functions not needed should be disabled. In particular, the following modules may need special
consideration when trying to achieve the lowest possible power consumption.
7.2.1
Analog to Digital Converter
If enabled, the ADC will be enabled in all sleep modes. To save power, the ADC should be disabled before entering any sleep mode. When the ADC is turned off and on again, the next
conversion will be an extended conversion. Refer to “Analog to Digital Converter” on page 81 for
details on ADC operation.
7.2.2
Analog Comparator
When entering Idle mode, the Analog Comparator should be disabled if not used. When entering
ADC Noise Reduction mode, the Analog Comparator should be disabled. In the other sleep
modes, the Analog Comparator is automatically disabled. However, if the Analog Comparator is
set up to use the Internal Voltage Reference as input, the Analog Comparator should be disabled in all sleep modes. Otherwise, the Internal Voltage Reference will be enabled,
independent of sleep mode. Refer to “Analog Comparator” on page 78 for details on how to configure the Analog Comparator.
7.2.3
Brown-out Detector
If the Brown-out Detector is not needed in the application, this module should be turned off. If the
Brown-out Detector is enabled by the BODLEVEL fuses, it will be enabled in all sleep modes,
and hence, always consume power. In the deeper sleep modes, this will contribute significantly
to the total current consumption. Refer to “Brown-out Detection” on page 36 for details on how to
configure the Brown-out Detector.
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7.2.4
Internal Voltage Reference
The Internal Voltage Reference will be enabled when needed by the Brown-out Detection, the
Analog Comparator or the ADC. If these modules are disabled as described in the sections
above, the internal voltage reference will be disabled and it will not be consuming power. When
turned on again, the user must allow the reference to start up before the output is used. If the
reference is kept on in sleep mode, the output can be used immediately. Refer to “Internal Voltage Reference” on page 37 for details on the start-up time.
7.2.5
Watchdog Timer
If the Watchdog Timer is not needed in the application, this module should be turned off. If the
Watchdog Timer is enabled, it will be enabled in all sleep modes, and hence, always consume
power. In the deeper sleep modes, this will contribute significantly to the total current consumption. Refer to “Interrupts” on page 44 for details on how to configure the Watchdog Timer.
7.2.6
Port Pins
When entering a sleep mode, all port pins should be configured to use minimum power. The
most important thing is then to ensure that no pins drive resistive loads. In sleep modes where
both the I/O clock (clkI/O) and the ADC clock (clkADC) are stopped, the input buffers of the device
will be disabled. This ensures that no power is consumed by the input logic when not needed. In
some cases, the input logic is needed for detecting wake-up conditions, and it will then be
enabled. Refer to the section “Digital Input Enable and Sleep Modes” on page 52 for details on
which pins are enabled. If the input buffer is enabled and the input signal is left floating or has an
analog signal level close to VCC/2, the input buffer will use excessive power.
For analog input pins, the digital input buffer should be disabled at all times. An analog signal
level close to VCC/2 on an input pin can cause significant current even in active mode. Digital
input buffers can be disabled by writing to the Digital Input Disable Register (DIDR0). Refer to
“DIDR0 – Digital Input Disable Register 0” on page 80 for details.
7.3
7.3.1
Register Description
MCUCR – MCU Control Register
The MCU Control Register contains control bits for power management.
Bit
7
6
5
4
3
2
1
0
–
PUD
SE
SM1
SM0
—
ISC01
ISC00
Read/Write
R
R/W
R/W
R/W
R/W
R
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
MCUCR
• Bit 5 – SE: Sleep Enable
The SE bit must be written to logic 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 write the Sleep Enable (SE) bit to one just before the execution of
the SLEEP instruction and to clear it immediately after waking up.
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ATtiny13
• Bits 4:3 – SM[1:0]: Sleep Mode Select Bits 1:0
These bits select between the three available sleep modes as shown in Table 7-2 on page 33.
Table 7-2.
Sleep Mode Select
SM1
SM0
Sleep Mode
0
0
Idle
0
1
ADC Noise Reduction
1
0
Power-down
1
1
Reserved
• Bit 2 – Res: Reserved Bit
This bit is a reserved bit in the ATtiny13 and will always read as zero.
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8. System Control and Reset
8.0.1
Resetting the AVR
During reset, all I/O Registers are set to their initial values, and the program starts execution
from the Reset Vector. The instruction placed at the Reset Vector must be a RJMP – Relative
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 8-1 on page 34 shows the reset logic. “System and
Reset Characteristics” on page 119 defines the electrical parameters of the reset circuitry.
Figure 8-1.
Reset Logic
DATA BUS
PORF
BORF
EXTRF
WDRF
MCU Status
Register (MCUSR)
Power-on Reset
Circuit
Brown-out
Reset Circuit
BODLEVEL [1..0]
Pull-up Resistor
SPIKE
FILTER
Watchdog
Oscillator
Clock
Generator
CK
Delay Counters
TIMEOUT
CKSEL[1:0]
SUT[1:0]
The I/O ports of the AVR are immediately reset to their initial state when a reset source goes
active. This does not require any clock source to be running.
After all reset sources have gone inactive, a delay counter is invoked, stretching the internal
reset. This allows the power to reach a stable level before normal operation starts. The time-out
period of the delay counter is defined by the user through the SUT and CKSEL fuses. The different selections for the delay period are presented in “Clock Sources” on page 24.
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ATtiny13
8.1
Reset Sources
The ATtiny13 has four sources of reset:
• Power-on Reset. The MCU is reset when the supply voltage is below the Power-on Reset
threshold (VPOT).
• External Reset. The MCU is reset when a low level is present on the RESET pin for longer
than the minimum pulse length.
• Watchdog Reset. The MCU is reset when the Watchdog Timer period expires and the
Watchdog is enabled.
• Brown-out Reset. The MCU is reset when the supply voltage VCC is below the Brown-out
Reset threshold (VBOT) and the Brown-out Detector is enabled.
8.1.1
Power-on Reset
A Power-on Reset (POR) pulse is generated by an On-chip detection circuit. The detection level
is defined in “System and Reset Characteristics” on page 119. The POR is activated whenever
VCC is below the detection level. The POR circuit can be used to trigger the Start-up Reset, as
well as to detect a failure in supply voltage.
A Power-on Reset (POR) circuit ensures that the device is reset from Power-on. Reaching the
Power-on Reset threshold voltage invokes the delay counter, which determines how long the
device is kept in RESET after VCC rise. The RESET signal is activated again, without any delay,
when VCC decreases below the detection level.
Figure 8-2.
VCC
RESET
MCU Start-up, RESET Tied to VCC
VPOT
VRST
tTOUT
TIME-OUT
INTERNAL
RESET
Figure 8-3.
VCC
RESET
TIME-OUT
MCU Start-up, RESET Extended Externally
VPOT
VRST
tTOUT
INTERNAL
RESET
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8.1.2
External Reset
An External Reset is generated by a low level on the RESET pin if enabled. Reset pulses longer
than the minimum pulse width (See “System and Reset Characteristics” on page 119.) 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 counter starts the MCU after the Time-out period – tTOUT – has expired.
Figure 8-4.
External Reset During Operation
CC
8.1.3
Brown-out Detection
ATtiny13 has an On-chip Brown-out Detection (BOD) circuit for monitoring the VCC level during
operation by comparing it to a fixed trigger level. The trigger level for the BOD can be selected
by the BODLEVEL fuses. The trigger level has a hysteresis to ensure spike free Brown-out
Detection. The hysteresis on the detection level should be interpreted as VBOT+ = VBOT + VHYST/2
and VBOT- = VBOT - VHYST/2.
When the BOD is enabled, and VCC decreases to a value below the trigger level (VBOT- in Figure
8-5 on page 36), the Brown-out Reset is immediately activated. When VCC increases above the
trigger level (VBOT+ in Figure 8-5 on page 36), the delay counter starts the MCU after the Timeout period tTOUT has expired.
The BOD circuit will only detect a drop in VCC if the voltage stays below the trigger level for
longer than tBOD given in “System and Reset Characteristics” on page 119.
Figure 8-5.
Brown-out Reset During Operation
VCC
VBOT-
VBOT+
RESET
TIME-OUT
tTOUT
INTERNAL
RESET
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ATtiny13
8.1.4
Watchdog Reset
When the Watchdog times out, it will generate a short reset pulse of one CK cycle duration. On
the falling edge of this pulse, the delay timer starts counting the Time-out period tTOUT. Refer to
“Interrupts” on page 44 for details on operation of the Watchdog Timer.
Figure 8-6.
Watchdog Reset During Operation
CC
CK
8.2
Internal Voltage Reference
ATtiny13 features an internal bandgap reference. This reference is used for Brown-out Detection, and it can be used as an input to the Analog Comparator or the ADC.
8.2.1
Voltage Reference Enable Signals and Start-up Time
The voltage reference has a start-up time that may influence the way it should be used. The
start-up time is given in “System and Reset Characteristics” on page 119. To save power, the
reference is not always turned on. The reference is on during the following situations:
• When the BOD is enabled (by programming the BODLEVEL [1..0] fuse).
• When the bandgap reference is connected to the Analog Comparator (by setting the ACBG
bit in ACSR).
• When the ADC is enabled.
Thus, when the BOD is not enabled, after setting the ACBG bit or enabling the ADC, the user
must always allow the reference to start up before the output from the Analog Comparator or
ADC is used. To reduce power consumption in Power-down mode, the user can avoid the three
conditions above to ensure that the reference is turned off before entering Power-down mode.
8.3
Watchdog Timer
ATtiny13 has an Enhanced Watchdog Timer (WDT). The WDT is a timer counting cycles of a
separate on-chip 128 kHz oscillator. The WDT gives an interrupt or a system reset when the
counter reaches a given time-out value. In normal operation mode, it is required that the system
uses the WDR - Watchdog Timer Reset - instruction to restart the counter before the time-out
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value is reached. If the system doesn't restart the counter, an interrupt or system reset will be
issued.
Watchdog Timer
128kHz
OSCILLATOR
WATCHDOG
RESET
WDE
OSC/2K
OSC/4K
OSC/8K
OSC/16K
OSC/32K
OSC/64K
OSC/128K
OSC/256K
OSC/512K
OSC/1024K
Figure 8-7.
WDP0
WDP1
WDP2
WDP3
MCU RESET
WDTIF
WDTIE
INTERRUPT
In Interrupt mode, the WDT gives an interrupt when the timer expires. This interrupt can be used
to wake the device from sleep-modes, and also as a general system timer. One example is to
limit the maximum time allowed for certain operations, giving an interrupt when the operation
has run longer than expected. In System Reset mode, the WDT gives a reset when the timer
expires. This is typically used to prevent system hang-up in case of runaway code. The third
mode, Interrupt and System Reset mode, combines the other two modes by first giving an interrupt and then switch to System Reset mode. This mode will for instance allow a safe shutdown
by saving critical parameters before a system reset.
The Watchdog always on (WDTON) fuse, if programmed, will force the Watchdog Timer to System Reset mode. With the fuse programmed the System Reset mode bit (WDE) and Interrupt
mode bit (WDTIE) are locked to 1 and 0 respectively. To further ensure program security, alterations to the Watchdog set-up must follow timed sequences. The sequence for clearing WDE
and changing time-out configuration is as follows:
1. In the same operation, write a logic one to the Watchdog change enable bit (WDCE)
and WDE. A logic one must be written to WDE regardless of the previous value of the
WDE bit.
2. Within the next four clock cycles, write the WDE and Watchdog prescaler bits (WDP) as
desired, but with the WDCE bit cleared. This must be done in one operation.
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ATtiny13
The following code example shows one assembly and one C function for turning off the Watchdog Timer. The example assumes that interrupts are controlled (e.g. by disabling interrupts
globally) so that no interrupts will occur during the execution of these functions.
Assembly Code Example(1)
WDT_off:
; Turn off global interrupt
cli
; Reset Watchdog Timer
wdr
; Clear WDRF in MCUSR
in
r16, MCUSR
andi
r16, (0xff - (1<<WDRF))
out
MCUSR, r16
; Write logical one to WDCE and WDE
; Keep old prescaler setting to prevent unintentional time-out
in
r16, WDTCR
ori
r16, (1<<WDCE) | (1<<WDE)
out
WDTCR, r16
; Turn off WDT
ldi
r16, (0<<WDE)
out
WDTCR, r16
; Turn on global interrupt
sei
ret
C Code Example(1)
void WDT_off(void)
{
__disable_interrupt();
__watchdog_reset();
/* Clear WDRF in MCUSR */
MCUSR &= ~(1<<WDRF);
/* Write logical one to WDCE and WDE */
/* Keep old prescaler setting to prevent unintentional time-out
*/
WDTCR |= (1<<WDCE) | (1<<WDE);
/* Turn off WDT */
WDTCR = 0x00;
__enable_interrupt();
}
Note:
1. The example code assumes that the part specific header file is included.
If the Watchdog is accidentally enabled, for example by a runaway pointer or brown-out condition, the device will be reset and the Watchdog Timer will stay enabled. If the code is not set up
to handle the Watchdog, this might lead to an eternal loop of time-out resets. To avoid this situa-
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tion, the application software should always clear the Watchdog System Reset Flag (WDRF)
and the WDE control bit in the initialisation routine, even if the Watchdog is not in use.
The following code example shows one assembly and one C function for changing the time-out
value of the Watchdog Timer.
Assembly Code Example(1)
WDT_Prescaler_Change:
; Turn off global interrupt
cli
; Reset Watchdog Timer
wdr
; Start timed sequence
in
r16, WDTCR
ori
r16, (1<<WDCE) | (1<<WDE)
out
WDTCR, r16
; --
Got four cycles to set the new values from here -
; Set new prescaler(time-out) value = 64K cycles (~0.5 s)
ldi
r16, (1<<WDE) | (1<<WDP2) | (1<<WDP0)
out
WDTCR, r16
; --
Finished setting new values, used 2 cycles -
; Turn on global interrupt
sei
ret
C Code Example(1)
void WDT_Prescaler_Change(void)
{
__disable_interrupt();
__watchdog_reset();
/* Start timed sequence */
WDTCR |= (1<<WDCE) | (1<<WDE);
/* Set new prescaler(time-out) value = 64K cycles (~0.5 s) */
WDTCR = (1<<WDE) | (1<<WDP2) | (1<<WDP0);
__enable_interrupt();
}
Note:
1. The example code assumes that the part specific header file is included.
The Watchdog Timer should be reset before any change of the WDP bits, since a change in the
WDP bits can result in a time-out when switching to a shorter time-out period.
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ATtiny13
8.4
8.4.1
Register Description
MCUSR – MCU Status Register
The MCU Status Register provides information on which reset source caused an MCU Reset.
Bit
7
6
5
4
3
2
1
0
–
–
–
–
WDRF
BORF
EXTRF
PORF
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
MCUSR
See Bit Description
• Bits 7:4 – Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and will always read as zero.
• Bit 3 – WDRF: Watchdog Reset Flag
This bit is set if a Watchdog Reset occurs. The bit is reset by a Power-on Reset, or by writing a
logic zero to the flag.
• Bit 2 – BORF: Brown-out Reset Flag
This bit is set if a Brown-out Reset occurs. The bit is reset by a Power-on Reset, or by writing a
logic zero to the flag.
• Bit 1 – EXTRF: External Reset Flag
This bit is set if an External Reset occurs. The bit is reset by a Power-on Reset, or by writing a
logic zero to the flag.
• Bit 0 – PORF: Power-on Reset Flag
This bit is set if a Power-on Reset occurs. The bit is reset only by writing a logic zero to the flag.
To make use of the Reset Flags to identify a reset condition, the user should read and then reset
the MCUSR as early as possible in the program. If the register is cleared before another reset
occurs, the source of the reset can be found by examining the Reset Flags.
8.4.2
WDTCR – Watchdog Timer Control Register
Bit
7
6
5
4
3
2
1
0
WDTIF
WDTIE
WDP3
WDCE
WDE
WDP2
WDP1
WDP0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
X
0
0
0
WDTCR
• Bit 7 - WDTIF: Watchdog Timer Interrupt Flag
This bit is set when a time-out occurs in the Watchdog Timer and the Watchdog Timer is configured for interrupt. WDTIF is cleared by hardware when executing the corresponding interrupt
handling vector. Alternatively, WDTIF is cleared by writing a logic one to the flag. When the I-bit
in SREG and WDTIE are set, the Watchdog Time-out Interrupt is executed.
• Bit 6 - WDTIE: Watchdog Timer Interrupt Enable
When this bit is written to one and the I-bit in the Status Register is set, the Watchdog Interrupt is
enabled. If WDE is cleared in combination with this setting, the Watchdog Timer is in Interrupt
Mode, and the corresponding interrupt is executed if time-out in the Watchdog Timer occurs.
If WDE is set, the Watchdog Timer is in Interrupt and System Reset Mode. The first time-out in
the Watchdog Timer will set WDTIF. Executing the corresponding interrupt vector will clear
WDTIE and WDTIF automatically by hardware (the Watchdog goes to System Reset Mode).
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This is useful for keeping the Watchdog Timer security while using the interrupt. To stay in Interrupt and System Reset Mode, WDTIE must be set after each interrupt. This should however not
be done within the interrupt service routine itself, as this might compromise the safety-function of
the Watchdog System Reset mode. If the interrupt is not executed before the next time-out, a
System Reset will be applied.
Table 8-1.
Watchdog Timer Configuration
(1)
WDTON
WDE
WDTIE
Mode
Action on Time-out
1
0
0
Stopped
None
1
0
1
Interrupt Mode
Interrupt
1
1
0
System Reset Mode
Reset
1
1
1
Interrupt and System Reset
Mode
Interrupt, then go to System
Reset Mode
0
x
x
System Reset Mode
Reset
Note:
1. WDTON fuse set to “0“ means programmed and “1“ means unprogrammed.
• Bit 4 - WDCE: Watchdog Change Enable
This bit is used in timed sequences for changing WDE and prescaler bits. To clear the WDE bit,
and/or change the prescaler bits, WDCE must be set.
Once written to one, hardware will clear WDCE after four clock cycles.
• Bit 3 - WDE: Watchdog System Reset Enable
WDE is overridden by WDRF in MCUSR. This means that WDE is always set when WDRF is
set. To clear WDE, WDRF must be cleared first. This feature ensures multiple resets during conditions causing failure, and a safe start-up after the failure.
• Bit 5, 2:0 - WDP[3:0]: Watchdog Timer Prescaler 3, 2, 1 and 0
The WDP[3:0] bits determine the Watchdog Timer prescaling when the Watchdog Timer is running. The different prescaling values and their corresponding time-out periods are shown in
Table 8-2 on page 42..
Table 8-2.
42
Watchdog Timer Prescale Select
WDP3
WDP2
WDP1
WDP0
Number of WDT Oscillator
Cycles
Typical Time-out at
VCC = 5.0V
0
0
0
0
2K (2048) cycles
16 ms
0
0
0
1
4K (4096) cycles
32 ms
0
0
1
0
8K (8192) cycles
64 ms
0
0
1
1
16K (16384) cycles
0.125 s
0
1
0
0
32K (32768) cycles
0.25 s
0
1
0
1
64K (65536) cycles
0.5 s
0
1
1
0
128K (131072) cycles
1.0 s
0
1
1
1
256K (262144) cycles
2.0 s
1
0
0
0
512K (524288) cycles
4.0 s
1
0
0
1
1024K (1048576) cycles
8.0 s
ATtiny13
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ATtiny13
Table 8-2.
Watchdog Timer Prescale Select
WDP3
WDP2
WDP1
WDP0
1
0
1
0
1
0
1
1
1
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
Number of WDT Oscillator
Cycles
Typical Time-out at
VCC = 5.0V
Reserved
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9. Interrupts
This section describes the specifics of the interrupt handling as performed in ATtiny13. For a
general explanation of the AVR interrupt handling, refer to “Reset and Interrupt Handling” on
page 12.
9.1
Interrupt Vectors
The interrupt vectors of ATtiny13 are described in Table 9-1 below.
Table 9-1.
Reset and Interrupt Vectors
Vector No.
Program Address
Source
Interrupt Definition
1
0x0000
RESET
External Pin, Power-on Reset,
Brown-out Reset, Watchdog Reset
2
0x0001
INT0
External Interrupt Request 0
3
0x0002
PCINT0
Pin Change Interrupt Request 0
4
0x0003
TIM0_OVF
Timer/Counter Overflow
5
0x0004
EE_RDY
EEPROM Ready
6
0x0005
ANA_COMP
Analog Comparator
7
0x0006
TIM0_COMPA
Timer/Counter Compare Match A
8
0x0007
TIM0_COMPB
Timer/Counter Compare Match B
9
0x0008
WDT
Watchdog Time-out
10
0x0009
ADC
ADC Conversion Complete
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 most typical and general program setup for the Reset and Interrupt Vector Addresses in
ATtiny13 is:
Address Labels Code
Comments
0x0000
rjmp
RESET
; Reset Handler
0x0001
rjmp
EXT_INT0
; IRQ0 Handler
0x0002
rjmp
PCINT0
; PCINT0 Handler
0x0003
rjmp
TIM0_OVF
; Timer0 Overflow Handler
0x0004
rjmp
EE_RDY
; EEPROM Ready Handler
0x0005
rjmp
ANA_COMP
; Analog Comparator Handler
0x0006
rjmp
TIM0_COMPA
; Timer0 CompareA Handler
0x0007
rjmp
TIM0_COMPB
; Timer0 CompareB Handler
0x0008
rjmp
WATCHDOG
; Watchdog Interrupt Handler
0x0009
rjmp
ADC
; ADC Conversion Handler
;
0x000A
0x000B
RESET: ldi
out
0x000C
0x000D
...
44
r16, low(RAMEND); Main program start
SPL,r16
sei
<instr>
...
; Set Stack Pointer to top of RAM
; Enable interrupts
xxx
...
...
ATtiny13
2535I–AVR–05/08
ATtiny13
9.2
External Interrupts
The External Interrupts are triggered by the INT0 pin or any of the PCINT5..0 pins. Observe that,
if enabled, the interrupts will trigger even if the INT0 or PCINT5..0 pins are configured as outputs. This feature provides a way of generating a software interrupt. Pin change interrupts PCI
will trigger if any enabled PCINT5..0 pin toggles. The PCMSK Register control which pins contribute to the pin change interrupts. Pin change interrupts on PCINT5..0 are detected
asynchronously. This implies that these interrupts can be used for waking the part also from
sleep modes other than Idle mode.
The INT0 interrupts can be triggered by a falling or rising edge or a low level. This is set up as
indicated in the specification for the MCU Control Register – MCUCR. When the INT0 interrupt is
enabled and is configured as level triggered, the interrupt will trigger as long as the pin is held
low. Note that recognition of falling or rising edge interrupts on INT0 requires the presence of an
I/O clock, described in “Clock Systems and their Distribution” on page 23.
9.2.1
Low Level Interrupt
A low level interrupt on INT0 is detected asynchronously. This implies that this interrupt can be
used for waking the part also from sleep modes other than Idle mode. The I/O clock is halted in
all sleep modes except Idle mode.
Note that if a level triggered interrupt is used for wake-up from Power-down, the required level
must be held long enough for the MCU to complete the wake-up to trigger the level interrupt. If
the level disappears before the end of the Start-up Time, the MCU will still wake up, but no interrupt will be generated. The start-up time is defined by the SUT and CKSEL fuses as described in
“System Clock and Clock Options” on page 23.
If the low level on the interrupt pin is removed before the device has woken up then program
execution will not be diverted to the interrupt service routine but continue from the instruction following the SLEEP command.
9.2.2
Pin Change Interrupt Timing
An example of timing of a pin change interrupt is shown in Figure 9-1 below.
Figure 9-1.
Timing of pin change interrupts
pin_lat
PCINT(0)
LE
clk
D
pcint_in_(0)
Q
0
pcint_syn
pcint_setflag
PCIF
pin_sync
x
PCINT(0) in PCMSK(x)
clk
clk
PCINT(n)
pin_lat
pin_sync
pcint_in_(n)
pcint_syn
pcint_setflag
PCIF
45
2535I–AVR–05/08
9.3
9.3.1
Register Description
MCUCR – MCU Control Register
The External Interrupt Control Register A contains control bits for interrupt sense control.
Bit
7
6
5
4
3
2
1
0
–
PUD
SE
SM1
SM0
–
ISC01
ISC00
Read/Write
R
R/W
R/W
R/W
R/W
R
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
MCUCR
• Bits 1, 0 – ISC01, ISC00: Interrupt Sense Control 0 Bit 1 and Bit 0
The External Interrupt 0 is activated by the external pin INT0 if the SREG I-flag and the corresponding interrupt mask are set. The level and edges on the external INT0 pin that activate the
interrupt are defined in Table 9-2 on page 46. The value on the INT0 pin is sampled before
detecting edges. If edge or toggle interrupt is selected, pulses that last longer than one clock
period will generate an interrupt. Shorter pulses are not guaranteed to generate an interrupt. If
low level interrupt is selected, the low level must be held until the completion of the currently
executing instruction to generate an interrupt.
Table 9-2.
9.3.2
Interrupt 0 Sense Control
ISC01
ISC00
Description
0
0
The low level of INT0 generates an interrupt request.
0
1
Any logical change on INT0 generates an interrupt request.
1
0
The falling edge of INT0 generates an interrupt request.
1
1
The rising edge of INT0 generates an interrupt request.
GIMSK – General Interrupt Mask Register
Bit
7
6
5
4
3
2
1
0
–
INT0
PCIE
–
–
–
–
–
Read/Write
R
R/W
R/W
R
R
R
R
R
Initial Value
0
0
0
0
0
0
0
0
GIMSK
• Bits 7, 4:0 – Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and will always read as zero.
• Bit 6 – INT0: External Interrupt Request 0 Enable
When the INT0 bit is set (one) and the I-bit in the Status Register (SREG) is set (one), the external pin interrupt is enabled. The Interrupt Sense Control0 bits 1/0 (ISC01 and ISC00) in the MCU
Control Register (MCUCR) define whether the external interrupt is activated on rising and/or falling edge of the INT0 pin or level sensed. Activity on the pin will cause an interrupt request even
if INT0 is configured as an output. The corresponding interrupt of External Interrupt Request 0 is
executed from the INT0 Interrupt Vector.
• Bit 5 – PCIE: Pin Change Interrupt Enable
When the PCIE bit is set (one) and the I-bit in the Status Register (SREG) is set (one), pin
change interrupt is enabled. Any change on any enabled PCINT5..0 pin will cause an interrupt.
The corresponding interrupt of Pin Change Interrupt Request is executed from the PCI Interrupt
Vector. PCINT5..0 pins are enabled individually by the PCMSK Register.
46
ATtiny13
2535I–AVR–05/08
ATtiny13
9.3.3
GIFR – General Interrupt Flag Register
Bit
7
6
5
4
3
2
1
0
–
INTF0
PCIF
–
–
–
–
–
Read/Write
R
R/W
R/W
R
R
R
R
R
Initial Value
0
0
0
0
0
0
0
0
GIFR
• Bits 7, 4:0 – Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and will always read as zero.
• Bit 6 – INTF0: External Interrupt Flag 0
When an edge or logic change on the INT0 pin triggers an interrupt request, INTF0 becomes set
(one). If the I-bit in SREG and the INT0 bit in GIMSK are set (one), the MCU will jump to the corresponding Interrupt Vector. The flag is cleared when the interrupt routine is executed.
Alternatively, the flag can be cleared by writing a logical one to it. This flag is always cleared
when INT0 is configured as a level interrupt.
• Bit 5 – PCIF: Pin Change Interrupt Flag
When a logic change on any PCINT5:0 pin triggers an interrupt request, PCIF becomes set
(one). If the I-bit in SREG and the PCIE bit in GIMSK are set (one), the MCU will jump to the corresponding Interrupt Vector. The flag is cleared when the interrupt routine is executed.
Alternatively, the flag can be cleared by writing a logical one to it.
9.3.4
PCMSK – Pin Change Mask Register
Bit
7
6
5
4
3
2
1
0
–
–
PCINT5
PCINT4
PCINT3
PCINT2
PCINT1
PCINT0
Read/Write
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
PCMSK
• Bits 7, 6 – Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and will always read as zero.
• Bits 5:0 – PCINT5:0: Pin Change Enable Mask 5:0
Each PCINT5:0 bit selects whether pin change interrupt is enabled on the corresponding I/O pin.
If PCINT5:0 is set and the PCIE bit in GIMSK is set, pin change interrupt is enabled on the corresponding I/O pin. If PCINT5:0 is cleared, pin change interrupt on the corresponding I/O pin is
disabled.
47
2535I–AVR–05/08
10. I/O Ports
10.1
Overview
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 when changing drive value (if configured as output) or enabling/disabling of pull-up resistors (if configured as
input). Each output buffer has symmetrical drive characteristics with both high sink and source
capability. The pin driver is strong enough to drive LED displays directly. All port pins have individually selectable pull-up resistors with a supply-voltage invariant resistance. All I/O pins have
protection diodes to both VCC and Ground as indicated in Figure 10-1. Refer to “Electrical Characteristics” on page 115 for a complete list of parameters.
Figure 10-1. I/O Pin Equivalent Schematic
Rpu
Logic
Pxn
Cpin
See Figure
"General Digital I/O" for
Details
All registers and bit references in this section are written in general form. A lower case “x” represents the numbering letter for the port, and a lower case “n” represents the bit number. However,
when using the register or bit defines in a program, the precise form must be used. For example,
PORTB3 for bit no. 3 in Port B, here documented generally as PORTxn. The physical I/O Registers and bit locations are listed in “Register Description” on page 56.
Three I/O memory address locations are allocated for each port, one each for the Data Register
– PORTx, Data Direction Register – DDRx, and the Port Input Pins – PINx. The Port Input Pins
I/O location is read only, while the Data Register and the Data Direction Register are read/write.
However, writing a logic one to a bit in the PINx Register, will result in a toggle in the corresponding bit in the Data Register. In addition, the Pull-up Disable – PUD bit in MCUCR disables the
pull-up function for all pins in all ports when set.
Using the I/O port as General Digital I/O is described in “Ports as General Digital I/O” on page
49. Most port pins are multiplexed with alternate functions for the peripheral features on the
device. How each alternate function interferes with the port pin is described in “Alternate Port
Functions” on page 53. Refer to the individual module sections for a full description of the alternate functions.
48
ATtiny13
2535I–AVR–05/08
ATtiny13
Note that enabling the alternate function of some of the port pins does not affect the use of the
other pins in the port as general digital I/O.
10.2
Ports as General Digital I/O
The ports are bi-directional I/O ports with optional internal pull-ups. Figure 10-2 on page 49
shows a functional description of one I/O-port pin, here generically called Pxn.
Figure 10-2. General Digital I/O(1)
PUD
Q
D
DDxn
Q CLR
WDx
RESET
DATA BUS
RDx
1
Q
Pxn
D
0
PORTxn
Q CLR
RESET
WRx
WPx
RRx
SLEEP
SYNCHRONIZER
D
Q
L
Q
D
RPx
Q
PINxn
Q
clk I/O
PUD:
SLEEP:
clkI/O:
Note:
10.2.1
PULLUP DISABLE
SLEEP CONTROL
I/O CLOCK
WDx:
RDx:
WRx:
RRx:
RPx:
WPx:
WRITE DDRx
READ DDRx
WRITE PORTx
READ PORTx REGISTER
READ PORTx PIN
WRITE PINx REGISTER
1. WRx, WPx, WDx, RRx, RPx, and RDx are common to all pins within the same port. clkI/O,
SLEEP, and PUD are common to all ports.
Configuring the Pin
Each port pin consists of three register bits: DDxn, PORTxn, and PINxn. As shown in “Register
Description” on page 56, the DDxn bits are accessed at the DDRx I/O address, the PORTxn bits
at the PORTx I/O address, and the PINxn bits at the PINx I/O address.
The DDxn bit in the DDRx Register selects the direction of this pin. If DDxn is written logic one,
Pxn is configured as an output pin. If DDxn is written logic zero, Pxn is configured as an input
pin.
49
2535I–AVR–05/08
If PORTxn is written logic one when the pin is configured as an input pin, the pull-up resistor is
activated. To switch the pull-up resistor off, PORTxn has to be written logic zero or the pin has to
be configured as an output pin. The port pins are tri-stated when reset condition becomes active,
even if no clocks are running.
If PORTxn is written logic one when the pin is configured as an output pin, the port pin is driven
high (one). If PORTxn is written logic zero when the pin is configured as an output pin, the port
pin is driven low (zero).
10.2.2
Toggling the Pin
Writing a logic one to PINxn toggles the value of PORTxn, independent on the value of DDRxn.
Note that the SBI instruction can be used to toggle one single bit in a port.
10.2.3
Switching Between Input and Output
When switching between tri-state ({DDxn, PORTxn} = 0b00) and output high ({DDxn, PORTxn}
= 0b11), an intermediate state with either pull-up enabled {DDxn, PORTxn} = 0b01) or output
low ({DDxn, PORTxn} = 0b10) must occur. Normally, the pull-up enabled state is fully acceptable, as a high-impedant environment will not notice the difference between a strong high driver
and a pull-up. If this is not the case, the PUD bit in the MCUCR Register can be set to disable all
pull-ups in all ports.
Switching between input with pull-up and output low generates the same problem. The user
must use either the tri-state ({DDxn, PORTxn} = 0b00) or the output high state ({DDxn, PORTxn}
= 0b10) as an intermediate step.
Table 10-1 summarizes the control signals for the pin value.
Table 10-1.
10.2.4
50
Port Pin Configurations
DDxn
PORTxn
PUD
(in MCUCR)
I/O
Pull-up
0
0
X
Input
No
Tri-state (Hi-Z)
0
1
0
Input
Yes
Pxn will source current if ext. pulled low.
0
1
1
Input
No
Tri-state (Hi-Z)
1
0
X
Output
No
Output Low (Sink)
1
1
X
Output
No
Output High (Source)
Comment
Reading the Pin Value
Independent of the setting of Data Direction bit DDxn, the port pin can be read through the
PINxn Register bit. As shown in Figure 10-2 on page 49, the PINxn Register bit and the preceding latch constitute a synchronizer. This is needed to avoid metastability if the physical pin
changes value near the edge of the internal clock, but it also introduces a delay. Figure 10-3 on
page 51 shows a timing diagram of the synchronization when reading an externally applied pin
value. The maximum and minimum propagation delays are denoted t pd,max and t pd,min
respectively.
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 10-3. Synchronization when Reading an Externally Applied Pin value
SYSTEM CLK
INSTRUCTIONS
XXX
XXX
in r17, PINx
SYNC LATCH
PINxn
r17
0x00
0xFF
t pd, max
t pd, min
Consider the clock period starting shortly after the first falling edge of the system clock. The latch
is closed when the clock is low, and goes transparent when the clock is high, as indicated by the
shaded region of the “SYNC LATCH” signal. The signal value is latched when the system clock
goes low. It is clocked into the PINxn Register at the succeeding positive clock edge. As indicated by the two arrows tpd,max and tpd,min, a single signal transition on the pin will be delayed
between ½ and 1½ system clock period depending upon the time of assertion.
When reading back a software assigned pin value, a nop instruction must be inserted as indicated in Figure 10-4 on page 51. The out instruction sets the “SYNC LATCH” signal at the
positive edge of the clock. In this case, the delay tpd through the synchronizer is one system
clock period.
Figure 10-4. Synchronization when Reading a Software Assigned Pin Value
SYSTEM CLK
r16
INSTRUCTIONS
0xFF
out PORTx, r16
nop
in r17, PINx
SYNC LATCH
PINxn
r17
0x00
0xFF
t pd
51
2535I–AVR–05/08
The following code example shows how to set port B pins 0 and 1 high, 2 and 3 low, and define
the port pins from 4 to 5 as input with a pull-up assigned to port pin 4. The resulting pin values
are read back again, but as previously discussed, a nop instruction is included to be able to read
back the value recently assigned to some of the pins.
Assembly Code Example(1)
...
; Define pull-ups and set outputs high
; Define directions for port pins
ldi
r16,(1<<PB4)|(1<<PB1)|(1<<PB0)
ldi
r17,(1<<DDB3)|(1<<DDB2)|(1<<DDB1)|(1<<DDB0)
out
PORTB,r16
out
DDRB,r17
; Insert nop for synchronization
nop
; Read port pins
in
r16,PINB
...
C Code Example
unsigned char i;
...
/* Define pull-ups and set outputs high */
/* Define directions for port pins */
PORTB = (1<<PB4)|(1<<PB1)|(1<<PB0);
DDRB = (1<<DDB3)|(1<<DDB2)|(1<<DDB1)|(1<<DDB0);
/* Insert nop for synchronization*/
__no_operation();
/* Read port pins */
i = PINB;
...
Note:
10.2.5
1. For the assembly program, two temporary registers are used to minimize the time from pullups are set on pins 0, 1 and 4, until the direction bits are correctly set, defining bit 2 and 3 as
low and redefining bits 0 and 1 as strong high drivers.
Digital Input Enable and Sleep Modes
As shown in Figure 10-2 on page 49, the digital input signal can be clamped to ground at the
input of the schmitt-trigger. The signal denoted SLEEP in the figure, is set by the MCU Sleep
Controller in Power-down mode, Power-save mode, and Standby mode to avoid high power
consumption if some input signals are left floating, or have an analog signal level close to VCC/2.
SLEEP is overridden for port pins enabled as external interrupt pins. If the external interrupt
request is not enabled, SLEEP is active also for these pins. SLEEP is also overridden by various
other alternate functions as described in “Alternate Port Functions” on page 53.
If a logic high level (“one”) is present on an asynchronous external interrupt pin configured as
“Interrupt on Rising Edge, Falling Edge, or Any Logic Change on Pin” while the external interrupt
is not enabled, the corresponding External Interrupt Flag will be set when resuming from the
52
ATtiny13
2535I–AVR–05/08
ATtiny13
above mentioned Sleep mode, as the clamping in these sleep mode produces the requested
logic change.
10.2.6
Unconnected Pins
If some pins are unused, it is recommended to ensure that these pins have a defined level. Even
though most of the digital inputs are disabled in the deep sleep modes as described above, floating inputs should be avoided to reduce current consumption in all other modes where the digital
inputs are enabled (Reset, Active mode and Idle mode).
The simplest method to ensure a defined level of an unused pin, is to enable the internal pull-up.
In this case, the pull-up will be disabled during reset. If low power consumption during reset is
important, it is recommended to use an external pull-up or pull-down. Connecting unused pins
directly to VCC or GND is not recommended, since this may cause excessive currents if the pin is
accidentally configured as an output.
10.3
Alternate Port Functions
Most port pins have alternate functions in addition to being general digital I/Os. Figure 10-5
shows how port pin control signals from the simplified Figure 10-2 on page 49 can be overridden
by alternate functions.
Figure 10-5. Alternate Port Functions
PUOExn
PUOVxn
1
PUD
0
DDOExn
DDOVxn
1
Q D
DDxn
0
Q CLR
WDx
PVOExn
RESET
RDx
1
DATA BUS
PVOVxn
1
Pxn
Q
0
D
0
PORTxn
PTOExn
Q CLR
DIEOExn
WPx
DIEOVxn
RESET
WRx
1
0
RRx
SLEEP
SYNCHRONIZER
D
SET
Q
RPx
Q
D
PINxn
L
CLR
Q
CLR
Q
clk I/O
DIxn
AIOxn
PUOExn:
PUOVxn:
DDOExn:
DDOVxn:
PVOExn:
PVOVxn:
DIEOExn:
DIEOVxn:
SLEEP:
PTOExn:
Note:
Pxn PULL-UP OVERRIDE ENABLE
Pxn PULL-UP OVERRIDE VALUE
Pxn DATA DIRECTION OVERRIDE ENABLE
Pxn DATA DIRECTION OVERRIDE VALUE
Pxn PORT VALUE OVERRIDE ENABLE
Pxn PORT VALUE OVERRIDE VALUE
Pxn DIGITAL INPUT-ENABLE OVERRIDE ENABLE
Pxn DIGITAL INPUT-ENABLE OVERRIDE VALUE
SLEEP CONTROL
Pxn, PORT TOGGLE OVERRIDE ENABLE
PUD:
WDx:
RDx:
RRx:
WRx:
RPx:
WPx:
clkI/O:
DIxn:
AIOxn:
PULLUP DISABLE
WRITE DDRx
READ DDRx
READ PORTx REGISTER
WRITE PORTx
READ PORTx PIN
WRITE PINx
I/O CLOCK
DIGITAL INPUT PIN n ON PORTx
ANALOG INPUT/OUTPUT PIN n ON PORTx
WRx, WPx, WDx, RRx, RPx, and RDx are common to all pins within the same port. clkI/O, SLEEP,
and PUD are common to all ports. All other signals are unique for each pin.
53
2535I–AVR–05/08
The overriding signals may not be present in all port pins, but Figure 10-5 serves as a generic
description applicable to all port pins in the AVR microcontroller family.
Table 10-2 on page 54 summarizes the function of the overriding signals. The pin and port
indexes from Figure 10-5 on page 53 are not shown in the succeeding tables. The overriding
signals are generated internally in the modules having the alternate function.
Table 10-2.
Generic Description of Overriding Signals for Alternate Functions
Signal Name
Full Name
Description
PUOE
Pull-up
Override Enable
If this signal is set, the pull-up enable is controlled by the
PUOV signal. If this signal is cleared, the pull-up is enabled
when {DDxn, PORTxn, PUD} = 0b010.
PUOV
Pull-up
Override Value
If PUOE is set, the pull-up is enabled/disabled when PUOV
is set/cleared, regardless of the setting of the DDxn,
PORTxn, and PUD Register bits.
DDOE
Data Direction
Override Enable
If this signal is set, the Output Driver Enable is controlled by
the DDOV signal. If this signal is cleared, the Output driver
is enabled by the DDxn Register bit.
DDOV
Data Direction
Override Value
If DDOE is set, the Output Driver is enabled/disabled when
DDOV is set/cleared, regardless of the setting of the DDxn
Register bit.
PVOE
Port Value
Override Enable
If this signal is set and the Output Driver is enabled, the port
value is controlled by the PVOV signal. If PVOE is cleared,
and the Output Driver is enabled, the port Value is
controlled by the PORTxn Register bit.
PVOV
Port Value
Override Value
If PVOE is set, the port value is set to PVOV, regardless of
the setting of the PORTxn Register bit.
PTOE
Port Toggle
Override Enable
If PTOE is set, the PORTxn Register bit is inverted.
DIEOE
Digital Input Enable
Override Enable
If this bit is set, the Digital Input Enable is controlled by the
DIEOV signal. If this signal is cleared, the Digital Input
Enable is determined by MCU state (Normal mode, sleep
mode).
DIEOV
Digital Input Enable
Override Value
If DIEOE is set, the Digital Input is enabled/disabled when
DIEOV is set/cleared, regardless of the MCU state (Normal
mode, sleep mode).
DI
Digital Input
This is the Digital Input to alternate functions. In the figure,
the signal is connected to the output of the schmitt-trigger
but before the synchronizer. Unless the Digital Input is used
as a clock source, the module with the alternate function
will use its own synchronizer.
AIO
Analog Input/Output
This is the Analog Input/Output to/from alternate functions.
The signal is connected directly to the pad, and can be
used bi-directionally.
The following subsections shortly describe the alternate functions for each port, and relate the
overriding signals to the alternate function. Refer to the alternate function description for further
details.
10.3.1
54
Alternate Functions of Port B
The Port B pins with alternate function are shown in Table 10-3 on page 55.
ATtiny13
2535I–AVR–05/08
ATtiny13
Table 10-3.
Port B Pins Alternate Functions
Port Pin
Alternate Function
PB5
RESET: Reset Pin
dW:
debugWIRE I/O
ADC0: ADC Input Channel 0
PCINT5: Pin Change Interrupt, Source 5
PB4
ADC2: ADC Input Channel 2
PCINT4: Pin Change Interrupt 0, Source 4
PB3
CLKI:
External Clock Input
ADC3: ADC Input Channel 3
PCINT3: Pin Change Interrupt 0, Source 3
PB2
SCK:
Serial Clock Input
ADC1: ADC Input Channel 1
T0:
Timer/Counter0 Clock Source.
PCINT2: Pin Change Interrupt 0, Source 2
PB1
MISO: SPI Master Data Input / Slave Data Output
AIN1:
Analog Comparator, Negative Input
OC0B: Timer/Counter0 Compare Match B Output
INT0:
External Interrupt 0 Input
PCINT1:Pin Change Interrupt 0, Source 1
PB0
MOSI:: SPI Master Data Output / Slave Data Input
AIN0:
Analog Comparator, Positive Input
OC0A: Timer/Counter0 Compare Match A output
PCINT0: Pin Change Interrupt 0, Source 0
Table 10-4 and Table 10-5 relate the alternate functions of Port B to the overriding signals
shown in Figure 10-5 on page 53.
Table 10-4.
Overriding Signals for Alternate Functions in PB5:PB3
Signal
PB5/RESET/ADC0/PCINT5
PB4/ADC2/PCINT4
PB3/ADC3/CLKI/PCINT3
PUOE
RSTDISBL(1) • DWEN(1)
0
0
PUOV
1
0
0
0
0
(1)
(1)
DDOE
RSTDISBL
DDOV
debugWire Transmit
0
0
PVOE
0
0
0
PVOV
0
0
0
PTOE
0
0
0
DIEOE
RSTDISBL(1) + (PCINT5 •
PCIE + ADC0D)
PCINT4 • PCIE + ADC2D
PCINT3 • PCIE + ADC3D
DIEOV
ADC0D
ADC2D
ADC3D
DI
PCINT5 Input
PCINT4 Input
PCINT3 Input
AIO
RESET Input, ADC0 Input
ADC2 Input
ADC3 Input
Note:
• DWEN
1. 1 when the fuse is “0” (Programmed).
55
2535I–AVR–05/08
Table 10-5.
10.4
10.4.1
Overriding Signals for Alternate Functions in PB2:PB0
Signal
Name
PB2/SCK/ADC1/
T0/PCINT2
PB1/MISO/AIN1/
OC0B/INT0/PCINT1
PB0/MOSI/AIN0/
AREF/OC0A/PCINT0
PUOE
0
0
0
PUOV
0
0
0
DDOE
0
0
0
DDOV
0
0
0
PVOE
0
OC0B Enable
OC0A Enable
PVOV
0
OC0B
OC0A
PTOE
0
0
0
DIEOE
PCINT2 • PCIE + ADC1D
PCINT1 • PCIE + AIN1D
PCINT0 • PCIE + AIN0D
DIEOV
ADC1D
AIN1D
AIN0D
DI
T0/INT0/
PCINT2 Input
PCINT1 Input
PCINT0 Input
AIO
ADC1 Input
Analog Comparator
Negative Input
Analog Comparator Positive
Input
Register Description
MCUCR – MCU Control Register
Bit
7
6
5
4
3
2
1
0
–
PUD
SE
SM1
SM0
–
ISC01
ISC00
Read/Write
R
R/W
R/W
R/W
R/W
R
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
MCUCR
• Bits 7, 2– Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and will always read as zero.
• Bit 6 – PUD: Pull-up Disable
When this bit is written to one, the pull-ups in the I/O ports are disabled even if the DDxn and
PORTxn Registers are configured to enable the pull-ups ({DDxn, PORTxn} = 0b01). See “Configuring the Pin” on page 49 for more details about this feature.
10.4.2
PORTB – Port B Data Register
Bit
10.4.3
7
6
5
4
3
2
1
0
–
–
PORTB5
PORTB4
PORTB3
PORTB2
PORTB1
PORTB0
Read/Write
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
DDRB – Port B Data Direction Register
Bit
56
PORTB
7
6
5
4
3
2
1
0
–
–
DDB5
DDB4
DDB3
DDB2
DDB1
DDB0
Read/Write
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
DDRB
ATtiny13
2535I–AVR–05/08
ATtiny13
10.4.4
PINB – Port B Input Pins Address
Bit
7
6
5
4
3
2
1
0
–
–
PINB5
PINB4
PINB3
PINB2
PINB1
PINB0
Read/Write
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
N/A
N/A
N/A
N/A
N/A
N/A
PINB
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11. 8-bit Timer/Counter0 with PWM
11.1
Features
•
•
•
•
•
•
•
11.2
Two Independent Output Compare Units
Double Buffered Output Compare Registers
Clear Timer on Compare Match (Auto Reload)
Glitch Free, Phase Correct Pulse Width Modulator (PWM)
Variable PWM Period
Frequency Generator
Three Independent Interrupt Sources (TOV0, OCF0A, and OCF0B)
Overview
Timer/Counter0 is a general purpose 8-bit Timer/Counter module, with two independent Output
Compare Units, and with PWM support. It allows accurate program execution timing (event management) and wave generation.
A simplified block diagram of the 8-bit Timer/Counter is shown in Figure 11-1 on page 58. For
the actual placement of I/O pins, refer to “Pinout ATtiny13/ATtiny13V” on page 2. CPU accessible I/O Registers, including I/O bits and I/O pins, are shown in bold. The device-specific I/O
Register and bit locations are listed in the “Register Description” on page 69.
Figure 11-1. 8-bit Timer/Counter Block Diagram
Count
Clear
Direction
TOVn
(Int.Req.)
Control Logic
clkTn
Clock Select
Edge
Detector
TOP
Tn
BOTTOM
( From Prescaler )
Timer/Counter
TCNTn
=
=0
OCnA
(Int.Req.)
Waveform
Generation
=
OCnA
DATA BUS
OCRnA
Fixed
TOP
Value
Waveform
Generation
=
OCnB
OCRnB
TCCRnA
58
OCnB
(Int.Req.)
TCCRnB
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ATtiny13
11.2.1
Registers
The Timer/Counter (TCNT0) and Output Compare Registers (OCR0A and OCR0B) are 8-bit
registers. Interrupt request (abbreviated to Int.Req. in the figure) signals are all visible in the
Timer Interrupt Flag Register (TIFR0). All interrupts are individually masked with the Timer Interrupt Mask Register (TIMSK0). TIFR0 and TIMSK0 are not shown in the figure.
The Timer/Counter can be clocked internally, via the prescaler, or by an external clock source on
the T0 pin. The Clock Select logic block controls which clock source and edge the Timer/Counter
uses to increment (or decrement) its value. The Timer/Counter is inactive when no clock source
is selected. The output from the Clock Select logic is referred to as the timer clock (clkT0).
The double buffered Output Compare Registers (OCR0A and OCR0B) is compared with the
Timer/Counter value at all times. The result of the compare can be used by the Waveform Generator to generate a PWM or variable frequency output on the Output Compare pins (OC0A and
OC0B). See “Output Compare Unit” on page 60. for details. The Compare Match event will also
set the Compare Flag (OCF0A or OCF0B) which can be used to generate an Output Compare
interrupt request.
11.2.2
Definitions
Many register and bit references in this section are written in general form. A lower case “n”
replaces the Timer/Counter number, in this case 0. A lower case “x” replaces the Output Compare Unit, in this case Compare Unit A or Compare Unit B. However, when using the register or
bit defines in a program, the precise form must be used, i.e., TCNT0 for accessing
Timer/Counter0 counter value and so on.
The definitions in Table 11-1 on page 59 are also used extensively throughout the document.
Table 11-1.
11.3
Definitions
BOTTOM
The counter reaches the BOTTOM when it becomes 0x00.
MAX
The counter reaches its MAXimum when it becomes 0xFF (decimal 255).
TOP
The counter reaches the TOP when it becomes equal to the highest value in the
count sequence. The TOP value can be assigned to be the fixed value 0xFF
(MAX) or the value stored in the OCR0A Register. The assignment is dependent on the mode of operation.
Timer/Counter Clock Sources
The Timer/Counter can be clocked by an internal or an external clock source. The clock source
is selected by the Clock Select logic which is controlled by the Clock Select (CS02:0) bits
located in the Timer/Counter Control Register (TCCR0B). For details on clock sources and prescaler, see “Timer/Counter Prescaler” on page 76.
11.4
Counter Unit
The main part of the 8-bit Timer/Counter is the programmable bi-directional counter unit. Figure
11-2 shows a block diagram of the counter and its surroundings.
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Figure 11-2. Counter Unit Block Diagram
TOVn
(Int.Req.)
DATA BUS
Clock Select
count
clear
TCNTn
Control Logic
clkTn
Edge
Detector
Tn
direction
( From Prescaler )
bottom
top
Signal description (internal signals):
count
direction
clear
clkTn
top
bottom
Increment or decrement TCNT0 by 1.
Select between increment and decrement.
Clear TCNT0 (set all bits to zero).
Timer/Counter clock, referred to as clkT0 in the following.
Signalize that TCNT0 has reached maximum value.
Signalize that TCNT0 has reached minimum value (zero).
Depending of the mode of operation used, the counter is cleared, incremented, or decremented
at each timer clock (clkT0). clkT0 can be generated from an external or internal clock source,
selected by the Clock Select bits (CS02:0). When no clock source is selected (CS02:0 = 0) the
timer is stopped. However, the TCNT0 value can be accessed by the CPU, regardless of
whether clkT0 is present or not. A CPU write overrides (has priority over) all counter clear or
count operations.
The counting sequence is determined by the setting of the WGM01 and WGM00 bits located in
the Timer/Counter Control Register (TCCR0A) and the WGM02 bit located in the Timer/Counter
Control Register B (TCCR0B). There are close connections between how the counter behaves
(counts) and how waveforms are generated on the Output Compare output OC0A. For more
details about advanced counting sequences and waveform generation, see “Modes of Operation” on page 63.
The Timer/Counter Overflow Flag (TOV0) is set according to the mode of operation selected by
the WGM01:0 bits. TOV0 can be used for generating a CPU interrupt.
11.5
Output Compare Unit
The 8-bit comparator continuously compares TCNT0 with the Output Compare Registers
(OCR0A and OCR0B). Whenever TCNT0 equals OCR0A or OCR0B, the comparator signals a
match. A match will set the Output Compare Flag (OCF0A or OCF0B) at the next timer clock
cycle. If the corresponding interrupt is enabled, the Output Compare Flag generates an Output
Compare interrupt. The Output Compare Flag is automatically cleared when the interrupt is executed. Alternatively, the flag can be cleared by software by writing a logical one to its I/O bit
location. The Waveform Generator uses the match signal to generate an output according to
operating mode set by the WGM02:0 bits and Compare Output mode (COM0x1:0) bits. The max
and bottom signals are used by the Waveform Generator for handling the special cases of the
extreme values in some modes of operation (See “Modes of Operation” on page 63.).
Figure 11-3 on page 61 shows a block diagram of the Output Compare unit.
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ATtiny13
Figure 11-3. Output Compare Unit, Block Diagram
DATA BUS
OCRnx
TCNTn
= (8-bit Comparator )
OCFnx (Int.Req.)
top
bottom
Waveform Generator
OCnx
FOCn
WGMn1:0
COMnX1:0
The OCR0x Registers are double buffered when using any of the Pulse Width Modulation
(PWM) modes. For the normal and Clear Timer on Compare (CTC) modes of operation, the double buffering is disabled. The double buffering synchronizes the update of the OCR0x Compare
Registers to either top or bottom of the counting sequence. The synchronization prevents the
occurrence of odd-length, non-symmetrical PWM pulses, thereby making the output glitch-free.
The OCR0x Register access may seem complex, but this is not case. When the double buffering
is enabled, the CPU has access to the OCR0x Buffer Register, and if double buffering is disabled the CPU will access the OCR0x directly.
11.5.1
Force Output Compare
In non-PWM waveform generation modes, the match output of the comparator can be forced by
writing a one to the Force Output Compare (FOC0x) bit. Forcing Compare Match will not set the
OCF0x Flag or reload/clear the timer, but the OC0x pin will be updated as if a real Compare
Match had occurred (the COM0x1:0 bits settings define whether the OC0x pin is set, cleared or
toggled).
11.5.2
Compare Match Blocking by TCNT0 Write
All CPU write operations to the TCNT0 Register will block any Compare Match that occur in the
next timer clock cycle, even when the timer is stopped. This feature allows OCR0x to be initialized to the same value as TCNT0 without triggering an interrupt when the Timer/Counter clock is
enabled.
11.5.3
Using the Output Compare Unit
Since writing TCNT0 in any mode of operation will block all Compare Matches for one timer
clock cycle, there are risks involved when changing TCNT0 when using the Output Compare
Unit, independently of whether the Timer/Counter is running or not. If the value written to TCNT0
equals the OCR0x value, the Compare Match will be missed, resulting in incorrect waveform
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generation. Similarly, do not write the TCNT0 value equal to BOTTOM when the counter is
down-counting.
The setup of the OC0x should be performed before setting the Data Direction Register for the
port pin to output. The easiest way of setting the OC0x value is to use the Force Output Compare (FOC0x) strobe bits in Normal mode. The OC0x Registers keep their values even when
changing between Waveform Generation modes.
Be aware that the COM0x1:0 bits are not double buffered together with the compare value.
Changing the COM0x1:0 bits will take effect immediately.
11.6
Compare Match Output Unit
The Compare Output mode (COM0x1:0) bits have two functions. The Waveform Generator uses
the COM0x1:0 bits for defining the Output Compare (OC0x) state at the next Compare Match.
Also, the COM0x1:0 bits control the OC0x pin output source. Figure 11-4 on page 62 shows a
simplified schematic of the logic affected by the COM0x1:0 bit setting. The I/O Registers, I/O
bits, and I/O pins in the figure are shown in bold. Only the parts of the general I/O Port Control
Registers (DDR and PORT) that are affected by the COM0x1:0 bits are shown. When referring
to the OC0x state, the reference is for the internal OC0x Register, not the OC0x pin. If a system
reset occur, the OC0x Register is reset to “0”.
Figure 11-4. Compare Match Output Unit, Schematic
COMnx1
COMnx0
FOCn
Waveform
Generator
D
Q
1
OCnx
DATA BUS
D
0
OCn
Pin
Q
PORT
D
Q
DDR
clk I/O
The general I/O port function is overridden by the Output Compare (OC0x) from the Waveform
Generator if either of the COM0x1:0 bits are set. However, the OC0x pin direction (input or output) is still controlled by the Data Direction Register (DDR) for the port pin. The Data Direction
Register bit for the OC0x pin (DDR_OC0x) must be set as output before the OC0x value is visible on the pin. The port override function is independent of the Waveform Generation mode.
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ATtiny13
The design of the Output Compare pin logic allows initialization of the OC0x state before the output is enabled. Note that some COM0x1:0 bit settings are reserved for certain modes of
operation. See “Register Description” on page 69.
11.6.1
Compare Output Mode and Waveform Generation
The Waveform Generator uses the COM0x1:0 bits differently in Normal, CTC, and PWM modes.
For all modes, setting the COM0x1:0 = 0 tells the Waveform Generator that no action on the
OC0x Register is to be performed on the next Compare Match. For compare output actions in
the non-PWM modes refer to Table 11-2 on page 69. For fast PWM mode, refer to Table 11-3 on
page 70, and for phase correct PWM refer to Table 11-4 on page 70.
A change of the COM0x1:0 bits state will have effect at the first Compare Match after the bits are
written. For non-PWM modes, the action can be forced to have immediate effect by using the
FOC0x strobe bits.
11.7
Modes of Operation
The mode of operation, i.e., the behavior of the Timer/Counter and the Output Compare pins, is
defined by the combination of the Waveform Generation mode (WGM02:0) and Compare Output
mode (COM0x1:0) bits. The Compare Output mode bits do not affect the counting sequence,
while the Waveform Generation mode bits do. The COM0x1:0 bits control whether the PWM output generated should be inverted or not (inverted or non-inverted PWM). For non-PWM modes
the COM0x1:0 bits control whether the output should be set, cleared, or toggled at a Compare
Match (See “Compare Match Output Unit” on page 62.).
For detailed timing information refer to Figure 11-8 on page 68, Figure 11-9 on page 68, Figure
11-10 on page 68 and Figure 11-11 on page 69 in “Timer/Counter Timing Diagrams” on page
67.
11.7.1
Normal Mode
The simplest mode of operation is the Normal mode (WGM02:0 = 0). In this mode the counting
direction is always up (incrementing), and no counter clear is performed. The counter simply
overruns when it passes its maximum 8-bit value (TOP = 0xFF) and then restarts from the bottom (0x00). In normal operation the Timer/Counter Overflow Flag (TOV0) will be set in the same
timer clock cycle as the TCNT0 becomes zero. The TOV0 Flag in this case behaves like a ninth
bit, except that it is only set, not cleared. However, combined with the timer overflow interrupt
that automatically clears the TOV0 Flag, the timer resolution can be increased by software.
There are no special cases to consider in the Normal mode, a new counter value can be written
anytime.
The Output Compare Unit can be used to generate interrupts at some given time. Using the Output Compare to generate waveforms in Normal mode is not recommended, since this will
occupy too much of the CPU time.
11.7.2
Clear Timer on Compare Match (CTC) Mode
In Clear Timer on Compare or CTC mode (WGM02:0 = 2), the OCR0A Register is used to
manipulate the counter resolution. In CTC mode the counter is cleared to zero when the counter
value (TCNT0) matches the OCR0A. The OCR0A defines the top value for the counter, hence
also its resolution. This mode allows greater control of the Compare Match output frequency. It
also simplifies the operation of counting external events.
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The timing diagram for the CTC mode is shown in Figure 11-5 on page 64. The counter value
(TCNT0) increases until a Compare Match occurs between TCNT0 and OCR0A, and then
counter (TCNT0) is cleared.
Figure 11-5. CTC Mode, Timing Diagram
OCnx Interrupt Flag Set
TCNTn
OCn
(Toggle)
Period
(COMnx1:0 = 1)
1
2
3
4
An interrupt can be generated each time the counter value reaches the TOP value by using the
OCF0A Flag. If the interrupt is enabled, the interrupt handler routine can be used for updating
the TOP value. However, changing TOP to a value close to BOTTOM when the counter is running with none or a low prescaler value must be done with care since the CTC mode does not
have the double buffering feature. If the new value written to OCR0A is lower than the current
value of TCNT0, the counter will miss the Compare Match. The counter will then have to count to
its maximum value (0xFF) and wrap around starting at 0x00 before the Compare Match can
occur.
For generating a waveform output in CTC mode, the OC0A output can be set to toggle its logical
level on each Compare Match by setting the Compare Output mode bits to toggle mode
(COM0A1:0 = 1). The OC0A value will not be visible on the port pin unless the data direction for
the pin is set to output. The waveform generated will have a maximum frequency of fOC0 =
fclk_I/O/2 when OCR0A is set to zero (0x00). The waveform frequency is defined by the following
equation:
f clk_I/O
f OCnx = -------------------------------------------------2 ⋅ N ⋅ ( 1 + OCRnx )
The N variable represents the prescale factor (1, 8, 64, 256, or 1024).
As for the Normal mode of operation, the TOV0 Flag is set in the same timer clock cycle that the
counter counts from MAX to 0x00.
11.7.3
64
Fast PWM Mode
The fast Pulse Width Modulation or fast PWM mode (WGM02:0 = 3 or 7) provides a high frequency PWM waveform generation option. The fast PWM differs from the other PWM option by
its single-slope operation. The counter counts from BOTTOM to TOP then restarts from BOTTOM. TOP is defined as 0xFF when WGM2:0 = 3, and OCR0A when WGM2:0 = 7. In noninverting Compare Output mode, the Output Compare (OC0x) is cleared on the Compare Match
between TCNT0 and OCR0x, and set at BOTTOM. In inverting Compare Output mode, the output is set on Compare Match and cleared at BOTTOM. Due to the single-slope operation, the
operating frequency of the fast PWM mode can be twice as high as the phase correct PWM
mode that use dual-slope operation. This high frequency makes the fast PWM mode well suited
ATtiny13
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ATtiny13
for power regulation, rectification, and DAC applications. High frequency allows physically small
sized external components (coils, capacitors), and therefore reduces total system cost.
In fast PWM mode, the counter is incremented until the counter value matches the TOP value.
The counter is then cleared at the following timer clock cycle. The timing diagram for the fast
PWM mode is shown in Figure 11-6 on page 65. The TCNT0 value is in the timing diagram
shown as a histogram for illustrating the single-slope operation. The diagram includes noninverted and inverted PWM outputs. The small horizontal line marks on the TCNT0 slopes represent Compare Matches between OCR0x and TCNT0.
Figure 11-6. Fast PWM Mode, Timing Diagram
OCRnx Interrupt Flag Set
OCRnx Update and
TOVn Interrupt Flag Set
TCNTn
OCn
(COMnx1:0 = 2)
OCn
(COMnx1:0 = 3)
Period
1
2
3
4
5
6
7
The Timer/Counter Overflow Flag (TOV0) is set each time the counter reaches TOP. If the interrupt is enabled, the interrupt handler routine can be used for updating the compare value.
In fast PWM mode, the compare unit allows generation of PWM waveforms on the OC0x pins.
Setting the COM0x1:0 bits to two will produce a non-inverted PWM and an inverted PWM output
can be generated by setting the COM0x1:0 to three: Setting the COM0A1:0 bits to one allows
the AC0A pin to toggle on Compare Matches if the WGM02 bit is set. This option is not available
for the OC0B pin (See Table 11-3 on page 70). The actual OC0x value will only be visible on the
port pin if the data direction for the port pin is set as output. The PWM waveform is generated by
setting (or clearing) the OC0x Register at the Compare Match between OCR0x and TCNT0, and
clearing (or setting) the OC0x Register at the timer clock cycle the counter is cleared (changes
from TOP to BOTTOM).
The PWM frequency for the output can be calculated by the following equation:
f clk_I/O
f OCnxPWM = -----------------N ⋅ 256
The N variable represents the prescale factor (1, 8, 64, 256, or 1024).
The extreme values for the OCR0A Register represents special cases when generating a PWM
waveform output in the fast PWM mode. If the OCR0A is set equal to BOTTOM, the output will
be a narrow spike for each MAX+1 timer clock cycle. Setting the OCR0A equal to MAX will result
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in a constantly high or low output (depending on the polarity of the output set by the COM0A1:0
bits.)
A frequency (with 50% duty cycle) waveform output in fast PWM mode can be achieved by setting OC0x to toggle its logical level on each Compare Match (COM0x1:0 = 1). The waveform
generated will have a maximum frequency of fOC0 = fclk_I/O/2 when OCR0A is set to zero. This
feature is similar to the OC0A toggle in CTC mode, except the double buffer feature of the Output Compare unit is enabled in the fast PWM mode.
11.7.4
Phase Correct PWM Mode
The phase correct PWM mode (WGM02:0 = 1 or 5) provides a high resolution phase correct
PWM waveform generation option. The phase correct PWM mode is based on a dual-slope
operation. The counter counts repeatedly from BOTTOM to TOP and then from TOP to BOTTOM. TOP is defined as 0xFF when WGM2:0 = 1, and OCR0A when WGM2:0 = 5. In noninverting Compare Output mode, the Output Compare (OC0x) is cleared on the Compare Match
between TCNT0 and OCR0x while upcounting, and set on the Compare Match while downcounting. In inverting Output Compare mode, the operation is inverted. The dual-slope operation
has lower maximum operation frequency than single slope operation. However, due to the symmetric feature of the dual-slope PWM modes, these modes are preferred for motor control
applications.
In phase correct PWM mode the counter is incremented until the counter value matches TOP.
When the counter reaches TOP, it changes the count direction. The TCNT0 value will be equal
to TOP for one timer clock cycle. The timing diagram for the phase correct PWM mode is shown
on Figure 11-7 on page 66. The TCNT0 value is in the timing diagram shown as a histogram for
illustrating the dual-slope operation. The diagram includes non-inverted and inverted PWM outputs. The small horizontal line marks on the TCNT0 slopes represent Compare Matches
between OCR0x and TCNT0.
Figure 11-7. Phase Correct PWM Mode, Timing Diagram
OCnx Interrupt Flag Set
OCRnx Update
TOVn Interrupt Flag Set
TCNTn
OCn
(COMnx1:0 = 2)
OCn
(COMnx1:0 = 3)
Period
66
1
2
3
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The Timer/Counter Overflow Flag (TOV0) is set each time the counter reaches BOTTOM. The
Interrupt Flag can be used to generate an interrupt each time the counter reaches the BOTTOM
value.
In phase correct PWM mode, the compare unit allows generation of PWM waveforms on the
OC0x pins. Setting the COM0x1:0 bits to two will produce a non-inverted PWM. An inverted
PWM output can be generated by setting the COM0x1:0 to three: Setting the COM0A0 bits to
one allows the OC0A pin to toggle on Compare Matches if the WGM02 bit is set. This option is
not available for the OC0B pin (See Table 11-4 on page 70). The actual OC0x value will only be
visible on the port pin if the data direction for the port pin is set as output. The PWM waveform is
generated by clearing (or setting) the OC0x Register at the Compare Match between OCR0x
and TCNT0 when the counter increments, and setting (or clearing) the OC0x Register at Compare Match between OCR0x and TCNT0 when the counter decrements. The PWM frequency for
the output when using phase correct PWM can be calculated by the following equation:
f clk_I/O
f OCnxPCPWM = -----------------N ⋅ 510
The N variable represents the prescale factor (1, 8, 64, 256, or 1024).
The extreme values for the OCR0A Register represent special cases when generating a PWM
waveform output in the phase correct PWM mode. If the OCR0A is set equal to BOTTOM, the
output will be continuously low and if set equal to MAX the output will be continuously high for
non-inverted PWM mode. For inverted PWM the output will have the opposite logic values.
At the very start of period 2 in Figure 11-7 on page 66 OCn has a transition from high to low
even though there is no Compare Match. The point of this transition is to guarantee symmetry
around BOTTOM. There are two cases that give a transition without Compare Match.
• OCR0A changes its value from MAX, like in Figure 11-7 on page 66. When the OCR0A value
is MAX the OCn pin value is the same as the result of a down-counting Compare Match. To
ensure symmetry around BOTTOM the OCn value at MAX must correspond to the result of
an up-counting Compare Match.
• The timer starts counting from a value higher than the one in OCR0A, and for that reason
misses the Compare Match and hence the OCn change that would have happened on the
way up.
11.8
Timer/Counter Timing Diagrams
The Timer/Counter is a synchronous design and the timer clock (clkT0) is therefore shown as a
clock enable signal in the following figures. The figures include information on when Interrupt
Flags are set. Figure 11-8 on page 68 contains timing data for basic Timer/Counter operation.
The figure shows the count sequence close to the MAX value in all modes other than phase correct PWM mode.
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Figure 11-8. Timer/Counter Timing Diagram, no Prescaling
clkI/O
clkTn
(clkI/O /1)
TCNTn
MAX - 1
MAX
BOTTOM
BOTTOM + 1
TOVn
Figure 11-9 shows the same timing data, but with the prescaler enabled.
Figure 11-9. Timer/Counter Timing Diagram, with Prescaler (fclk_I/O/8)
clkI/O
clkTn
(clkI/O /8)
TCNTn
MAX - 1
MAX
BOTTOM
BOTTOM + 1
TOVn
Figure 11-10 shows the setting of OCF0B in all modes and OCF0A in all modes except CTC
mode and PWM mode, where OCR0A is TOP.
Figure 11-10. Timer/Counter Timing Diagram, Setting of OCF0x, with Prescaler (fclk_I/O/8)
clkI/O
clkTn
(clkI/O /8)
TCNTn
OCRnx
OCRnx - 1
OCRnx
OCRnx + 1
OCRnx + 2
OCRnx Value
OCFnx
Figure 11-11 on page 69 shows the setting of OCF0A and the clearing of TCNT0 in CTC mode
and fast PWM mode where OCR0A is TOP.
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Figure 11-11. Timer/Counter Timing Diagram, Clear Timer on Compare Match mode, with Prescaler (fclk_I/O/8)
clkI/O
clkTn
(clkI/O /8)
TCNTn
(CTC)
TOP - 1
TOP
BOTTOM
BOTTOM + 1
TOP
OCRnx
OCFnx
11.9
11.9.1
Register Description
TCCR0A – Timer/Counter Control Register A
Bit
7
6
5
4
3
2
1
0
COM0A1
COM0A0
COM0B1
COM0B0
–
–
WGM01
WGM00
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
TCCR0A
• Bits 7:6 – COM01A:0: Compare Match Output A Mode
These bits control the Output Compare pin (OC0A) behavior. If one or both of the COM0A1:0
bits are set, the OC0A output overrides the normal port functionality of the I/O pin it is connected
to. However, note that the Data Direction Register (DDR) bit corresponding to the OC0A pin
must be set in order to enable the output driver.
When OC0A is connected to the pin, the function of the COM0A1:0 bits depends on the
WGM02:0 bit setting.
Table 11-2 shows the COM0A1:0 bit functionality when the WGM02:0 bits are set to a normal or
CTC mode (non-PWM).
Table 11-2.
Compare Output Mode, non-PWM Mode
COM01
COM00
Description
0
0
Normal port operation, OC0A disconnected.
0
1
Toggle OC0A on Compare Match
1
0
Clear OC0A on Compare Match
1
1
Set OC0A on Compare Match
Table 11-3 on page 70 shows the COM0A1:0 bit functionality when the WGM01:0 bits are set to
fast PWM mode.
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Table 11-3.
Compare Output Mode, Fast PWM Mode(1)
COM01
COM00
0
0
Normal port operation, OC0A disconnected.
0
1
WGM02 = 0: Normal Port Operation, OC0A Disconnected.
WGM02 = 1: Toggle OC0A on Compare Match.
1
0
Clear OC0A on Compare Match, set OC0A at TOP
1
1
Set OC0A on Compare Match, clear OC0A at TOP
Note:
Description
1. A special case occurs when OCR0A equals TOP and COM0A1 is set. In this case, the Compare Match is ignored, but the set or clear is done at TOP. See “Fast PWM Mode” on page 64
for more details.
Table 11-4 shows the COM0A1:0 bit functionality when the WGM02:0 bits are set to phase correct PWM mode.
Table 11-4.
Compare Output Mode, Phase Correct PWM Mode(1)
COM0A1
COM0A0
0
0
Normal port operation, OC0A disconnected.
0
1
WGM02 = 0: Normal Port Operation, OC0A Disconnected.
WGM02 = 1: Toggle OC0A on Compare Match.
1
0
Clear OC0A on Compare Match when up-counting. Set OC0A on
Compare Match when down-counting.
1
1
Set OC0A on Compare Match when up-counting. Clear OC0A on
Compare Match when down-counting.
Note:
Description
1. A special case occurs when OCR0A equals TOP and COM0A1 is set. In this case, the Compare Match is ignored, but the set or clear is done at TOP. See “Phase Correct PWM Mode” on
page 66 for more details.
• Bits 5:4 – COM0B1:0: Compare Match Output B Mode
These bits control the Output Compare pin (OC0B) behavior. If one or both of the COM0B1:0
bits are set, the OC0B output overrides the normal port functionality of the I/O pin it is connected
to. However, note that the Data Direction Register (DDR) bit corresponding to the OC0B pin
must be set in order to enable the output driver.
When OC0B is connected to the pin, the function of the COM0B1:0 bits depends on the
WGM02:0 bit setting.
Table 11-5 on page 71 shows the COM0B1:0 bit functionality when the WGM02:0 bits are set to
a normal or CTC mode (non-PWM).
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Table 11-5.
Compare Output Mode, non-PWM Mode
COM01
COM00
Description
0
0
Normal port operation, OC0B disconnected.
0
1
Toggle OC0B on Compare Match
1
0
Clear OC0B on Compare Match
1
1
Set OC0B on Compare Match
Table 11-6 shows the COM0B1:0 bit functionality when the WGM02:0 bits are set to fast PWM
mode.
Table 11-6.
Compare Output Mode, Fast PWM Mode(1)
COM01
COM00
0
0
Normal port operation, OC0B disconnected.
0
1
Reserved
1
0
Clear OC0B on Compare Match, set OC0B at TOP
1
1
Set OC0B on Compare Match, clear OC0B at TOP
Note:
Description
1. A special case occurs when OCR0B equals TOP and COM0B1 is set. In this case, the Compare Match is ignored, but the set or clear is done at TOP. See “Fast PWM Mode” on page 64
for more details.
Table 11-7 shows the COM0B1:0 bit functionality when the WGM02:0 bits are set to phase correct PWM mode.
Table 11-7.
Compare Output Mode, Phase Correct PWM Mode(1)
COM0A1
COM0A0
0
0
Normal port operation, OC0B disconnected.
0
1
Reserved
1
0
Clear OC0B on Compare Match when up-counting. Set OC0B on
Compare Match when down-counting.
1
1
Set OC0B on Compare Match when up-counting. Clear OC0B on
Compare Match when down-counting.
Note:
Description
1. A special case occurs when OCR0B equals TOP and COM0B1 is set. In this case, the Compare Match is ignored, but the set or clear is done at TOP. See “Phase Correct PWM Mode” on
page 66 for more details.
• Bits 3, 2 – Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and will always read as zero.
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• Bits 1:0 – WGM01:0: Waveform Generation Mode
Combined with the WGM02 bit found in the TCCR0B Register, these bits control the counting
sequence of the counter, the source for maximum (TOP) counter value, and what type of waveform generation to be used, see Table 11-8 on page 72. Modes of operation supported by the
Timer/Counter unit are: Normal mode (counter), Clear Timer on Compare Match (CTC) mode,
and two types of Pulse Width Modulation (PWM) modes (see “Modes of Operation” on page 63).
Table 11-8.
Timer/Counter
Mode of
Operation
TOP
Update of
OCRx at
TOV Flag
Set on(1)(2)
Mode
WGM2
WGM1
WGM0
0
0
0
0
Normal
0xFF
Immediate
MAX
1
0
0
1
PWM
(Phase Correct)
0xFF
TOP
BOTTOM
2
0
1
0
CTC
OCRA
Immediate
MAX
3
0
1
1
Fast PWM
0xFF
TOP
MAX
4
1
0
0
Reserved
–
–
–
5
1
0
1
PWM
(Phase Correct)
OCRA
TOP
BOTTOM
6
1
1
0
Reserved
–
–
–
7
1
1
1
Fast PWM
OCRA
TOP
TOP
Notes:
11.9.2
Waveform Generation Mode Bit Description
1. MAX
= 0xFF
2. BOTTOM = 0x00
TCCR0B – Timer/Counter Control Register B
Bit
7
6
5
4
3
2
1
0
FOC0A
FOC0B
–
–
WGM02
CS02
CS01
CS00
Read/Write
W
W
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
TCCR0B
• Bit 7 – FOC0A: Force Output Compare A
The FOC0A bit is only active when the WGM bits specify a non-PWM mode.
However, for ensuring compatibility with future devices, this bit must be set to zero when
TCCR0B is written when operating in PWM mode. When writing a logical one to the FOC0A bit,
an immediate Compare Match is forced on the Waveform Generation unit. The OC0A output is
changed according to its COM0A1:0 bits setting. Note that the FOC0A bit is implemented as a
strobe. Therefore it is the value present in the COM0A1:0 bits that determines the effect of the
forced compare.
A FOC0A strobe will not generate any interrupt, nor will it clear the timer in CTC mode using
OCR0A as TOP.
The FOC0A bit is always read as zero.
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• Bit 6 – FOC0B: Force Output Compare B
The FOC0B bit is only active when the WGM bits specify a non-PWM mode.
However, for ensuring compatibility with future devices, this bit must be set to zero when
TCCR0B is written when operating in PWM mode. When writing a logical one to the FOC0B bit,
an immediate Compare Match is forced on the Waveform Generation unit. The OC0B output is
changed according to its COM0B1:0 bits setting. Note that the FOC0B bit is implemented as a
strobe. Therefore it is the value present in the COM0B1:0 bits that determines the effect of the
forced compare.
A FOC0B strobe will not generate any interrupt, nor will it clear the timer in CTC mode using
OCR0B as TOP.
The FOC0B bit is always read as zero.
• Bits 5:4 – Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and will always read as zero.
• Bit 3 – WGM02: Waveform Generation Mode
See the description in the “TCCR0A – Timer/Counter Control Register A” on page 69.
• Bits 2:0 – CS02:0: Clock Select
The three Clock Select bits select the clock source to be used by the Timer/Counter.
Table 11-9.
Clock Select Bit Description
CS02
CS01
CS00
Description
0
0
0
No clock source (Timer/Counter stopped)
0
0
1
clkI/O/(No prescaling)
0
1
0
clkI/O/8 (From prescaler)
0
1
1
clkI/O/64 (From prescaler)
1
0
0
clkI/O/256 (From prescaler)
1
0
1
clkI/O/1024 (From prescaler)
1
1
0
External clock source on T0 pin. Clock on falling edge.
1
1
1
External clock source on T0 pin. Clock on rising edge.
If external pin modes are used for the Timer/Counter0, transitions on the T0 pin will clock the
counter even if the pin is configured as an output. This feature allows software control of the
counting.
11.9.3
TCNT0 – Timer/Counter Register
Bit
7
6
5
4
3
2
1
0
TCNT0[7:0]
TCNT0
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
The Timer/Counter Register gives direct access, both for read and write operations, to the
Timer/Counter unit 8-bit counter. Writing to the TCNT0 Register blocks (removes) the Compare
Match on the following timer clock. Modifying the counter (TCNT0) while the counter is running,
introduces a risk of missing a Compare Match between TCNT0 and the OCR0x Registers.
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11.9.4
OCR0A – Output Compare Register A
Bit
7
6
5
4
3
2
1
0
OCR0A[7:0]
OCR0A
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
The Output Compare Register A contains an 8-bit value that is continuously compared with the
counter value (TCNT0). A match can be used to generate an Output Compare interrupt, or to
generate a waveform output on the OC0A pin.
11.9.5
OCR0B – Output Compare Register B
Bit
7
6
5
4
3
2
1
0
OCR0B[7:0]
OCR0B
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
The Output Compare Register B contains an 8-bit value that is continuously compared with the
counter value (TCNT0). A match can be used to generate an Output Compare interrupt, or to
generate a waveform output on the OC0B pin.
11.9.6
TIMSK0 – Timer/Counter Interrupt Mask Register
Bit
7
6
5
4
3
2
1
0
–
–
–
–
OCIE0B
OCIE0A
TOIE0
–
Read/Write
R
R
R
R
R/W
R/W
R/W
R
Initial Value
0
0
0
0
0
0
0
0
TIMSK0
• Bits 7:4, 0 – Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and will always read as zero.
• Bit 3 – OCIE0B: Timer/Counter Output Compare Match B Interrupt Enable
When the OCIE0B bit is written to one, and the I-bit in the Status Register is set, the
Timer/Counter Compare Match B interrupt is enabled. The corresponding interrupt is executed if
a Compare Match in Timer/Counter occurs, i.e., when the OCF0B bit is set in the Timer/Counter
Interrupt Flag Register – TIFR0.
• Bit 2 – OCIE0A: Timer/Counter0 Output Compare Match A Interrupt Enable
When the OCIE0A bit is written to one, and the I-bit in the Status Register is set, the
Timer/Counter0 Compare Match A interrupt is enabled. The corresponding interrupt is executed
if a Compare Match in Timer/Counter0 occurs, i.e., when the OCF0A bit is set in the
Timer/Counter 0 Interrupt Flag Register – TIFR0.
• Bit 1 – TOIE0: Timer/Counter0 Overflow Interrupt Enable
When the TOIE0 bit is written to one, and the I-bit in the Status Register is set, the
Timer/Counter0 Overflow interrupt is enabled. The corresponding interrupt is executed if an
overflow in Timer/Counter0 occurs, i.e., when the TOV0 bit is set in the Timer/Counter 0 Interrupt Flag Register – TIFR0.
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11.9.7
TIFR0 – Timer/Counter 0 Interrupt Flag Register
Bit
7
6
5
4
3
2
1
–
–
–
–
OCF0B
OCF0A
TOV0
0
–
Read/Write
R
R
R
R
R/W
R/W
R/W
R
Initial Value
0
0
0
0
0
0
0
0
TIFR0
• Bits 7:4, 0 – Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and will always read as zero.
• Bit 3 – OCF0B: Output Compare Flag 0 B
The OCF0B bit is set when a Compare Match occurs between the Timer/Counter and the data in
OCR0B – Output Compare Register0 B. OCF0B is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, OCF0B is cleared by writing a logic one to
the flag. When the I-bit in SREG, OCIE0B (Timer/Counter Compare B Match Interrupt Enable),
and OCF0B are set, the Timer/Counter Compare Match Interrupt is executed.
• Bit 2 – OCF0A: Output Compare Flag 0 A
The OCF0A bit is set when a Compare Match occurs between the Timer/Counter0 and the data
in OCR0A – Output Compare Register0. OCF0A is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, OCF0A is cleared by writing a logic one to
the flag. When the I-bit in SREG, OCIE0A (Timer/Counter0 Compare Match Interrupt Enable),
and OCF0A are set, the Timer/Counter0 Compare Match Interrupt is executed.
• Bit 1 – TOV0: Timer/Counter0 Overflow Flag
The bit TOV0 is set when an overflow occurs in Timer/Counter0. TOV0 is cleared by hardware
when executing the corresponding interrupt handling vector. Alternatively, TOV0 is cleared by
writing a logic one to the flag. When the SREG I-bit, TOIE0 (Timer/Counter0 Overflow Interrupt
Enable), and TOV0 are set, the Timer/Counter0 Overflow interrupt is executed.
The setting of this flag is dependent of the WGM02:0 bit setting. Refer to Table 11-8, “Waveform
Generation Mode Bit Description” on page 72.
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12. Timer/Counter Prescaler
12.1
Overview
The Timer/Counter can be clocked directly by the system clock (by setting the CSn2:0 = 1). This
provides the fastest operation, with a maximum Timer/Counter clock frequency equal to system
clock frequency (fCLK_I/O). Alternatively, one of four taps from the prescaler can be used as a
clock source. The prescaled clock has a frequency of either fCLK_I/O/8, fCLK_I/O/64, fCLK_I/O/256, or
fCLK_I/O/1024.
12.2
Prescaler Reset
The prescaler is free running, i.e., operates independently of the Clock Select logic of the
Timer/Counter. Since the prescaler is not affected by the Timer/Counter’s clock select, the state
of the prescaler will have implications for situations where a prescaled clock is used. One example of prescaling artifacts occurs when the timer is enabled and clocked by the prescaler (6 >
CSn2:0 > 1). The number of system clock cycles from when the timer is enabled to the first count
occurs can be from 1 to N+1 system clock cycles, where N equals the prescaler divisor (8, 64,
256, or 1024).
It is possible to use the Prescaler Reset for synchronizing the Timer/Counter to program
execution.
12.3
External Clock Source
An external clock source applied to the T0 pin can be used as Timer/Counter clock (clkT0). The
T0 pin is sampled once every system clock cycle by the pin synchronization logic. The synchronized (sampled) signal is then passed through the edge detector. Figure 12-1 on page 76 shows
a functional equivalent block diagram of the T0 synchronization and edge detector logic. The
registers are clocked at the positive edge of the internal system clock (clkI/O). The latch is transparent in the high period of the internal system clock.
The edge detector generates one clkT0 pulse for each positive (CSn2:0 = 7) or negative (CSn2:0
= 6) edge it detects.
Figure 12-1. T0 Pin Sampling
Tn
D
Q
D
Q
D
Tn_sync
(To Clock
Select Logic)
Q
LE
clk I/O
Synchronization
Edge Detector
The synchronization and edge detector logic introduces a delay of 2.5 to 3.5 system clock cycles
from an edge has been applied to the T0 pin to the counter is updated.
Enabling and disabling of the clock input must be done when T0 has been stable for at least one
system clock cycle, otherwise it is a risk that a false Timer/Counter clock pulse is generated.
Each half period of the external clock applied must be longer than one system clock cycle to
ensure correct sampling. The external clock must be guaranteed to have less than half the system clock frequency (fExtClk < fclk_I/O/2) given a 50/50% duty cycle. Since the edge detector uses
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sampling, the maximum frequency of an external clock it can detect is half the sampling frequency (Nyquist sampling theorem). However, due to variation of the system clock frequency
and duty cycle caused by Oscillator source (crystal, resonator, and capacitors) tolerances, it is
recommended that maximum frequency of an external clock source is less than fclk_I/O/2.5.
An external clock source can not be prescaled.
Figure 12-2. Prescaler for Timer/Counter0
clk I/O
Clear
PSR10
T0
Synchronization
clkT0
Note:
12.4
12.4.1
1. The synchronization logic on the input pins (T0) is shown in Figure 12-1 on page 76.
Register Description.
GTCCR – General Timer/Counter Control Register
Bit
7
6
5
4
3
2
1
0
TSM
–
–
–
–
–
–
PSR10
Read/Write
R/W
R
R
R
R
R
R
R/W
Initial Value
0
0
0
0
0
0
0
0
GTCCR
• Bit 7 – TSM: Timer/Counter Synchronization Mode
Writing the TSM bit to one activates the Timer/Counter Synchronization mode. In this mode, the
value that is written to the PSR10 bit is kept, hence keeping the Prescaler Reset signal asserted.
This ensures that the Timer/Counter is halted and can be configured without the risk of advancing during configuration. When the TSM bit is written to zero, the PSR10 bit is cleared by
hardware, and the Timer/Counter start counting.
• Bit 0 – PSR10: Prescaler Reset Timer/Counter0
When this bit is one, the Timer/Counter0 prescaler will be Reset. This bit is normally cleared
immediately by hardware, except if the TSM bit is set.
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13. Analog Comparator
The Analog Comparator compares the input values on the positive pin AIN0 and negative pin
AIN1. When the voltage on the positive pin AIN0 is higher than the voltage on the negative pin
AIN1, the Analog Comparator output, ACO, is set. 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 13-1 on page 78.
Figure 13-1. Analog Comparator Block Diagram
BANDGAP
REFERENCE
ACBG
ACME
ADEN
ADC MULTIPLEXER
OUTPUT (1)
See Figure 1-1 on page 2, Table 10-5 on page 56, and Table 13-2 on page 80 for Analog Comparator pin placement.
13.1
Analog Comparator Multiplexed Input
It is possible to select any of the ADC3..0 pins to replace the negative input to the Analog Comparator. The ADC multiplexer is used to select this input, and consequently, the ADC must be
switched off to utilize this feature. If the Analog Comparator Multiplexer Enable bit (ACME in
ADCSRB) is set and the ADC is switched off (ADEN in ADCSRA is zero), MUX1:0 in ADMUX
select the input pin to replace the negative input to the Analog Comparator, as shown in Table
13-1. If ACME is cleared or ADEN is set, AIN1 is applied to the negative input to the Analog
Comparator.
Table 13-1.
78
Analog Comparator Multiplexed Input
ACME
ADEN
MUX1..0
Analog Comparator Negative Input
0
x
xx
AIN1
1
1
xx
AIN1
1
0
00
ADC0
1
0
01
ADC1
1
0
10
ADC2
1
0
11
ADC3
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ATtiny13
13.2
13.2.1
Register Description
ADCSRB – ADC Control and Status Register
Bit
7
6
5
4
3
2
1
0
–
ACME
–
–
–
ADTS2
ADTS1
ADTS0
Read/Write
R
R/W
R
R
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
ADCSRB
• Bit 6 – ACME: Analog Comparator Multiplexer Enable
When this bit is written logic one and the ADC is switched off (ADEN in ADCSRA is zero), the
ADC multiplexer selects the negative input to the Analog Comparator. When this bit is written
logic zero, AIN1 is applied to the negative input of the Analog Comparator. For a detailed
description of this bit, see “Analog Comparator Multiplexed Input” on page 78.
13.2.2
ACSR– Analog Comparator Control and Status Register
Bit
7
6
5
4
3
2
1
0
ACD
ACBG
ACO
ACI
ACIE
–
ACIS1
ACIS0
Read/Write
R/W
R/W
R
R/W
R/W
R
R/W
R/W
Initial Value
0
0
N/A
0
0
0
0
0
ACSR
• Bit 7 – ACD: Analog Comparator Disable
When this bit is written logic one, the power to the Analog Comparator is switched off. This bit
can be set at any time to turn off the Analog Comparator. This will reduce power consumption in
Active and Idle mode. When changing the ACD bit, the Analog Comparator Interrupt must be
disabled by clearing the ACIE bit in ACSR. Otherwise an interrupt can occur when the bit is
changed.
• Bit 6 – ACBG: Analog Comparator Bandgap Select
When this bit is set, a fixed bandgap reference voltage replaces the positive input to the Analog
Comparator. When this bit is cleared, AIN0 is applied to the positive input of the Analog Comparator. When the bandgap reference is used as input to the Analog Comparator, it will take certain
time for the voltage to stabilize. If not stabilized, the first value may give a wrong value.
• Bit 5 – ACO: Analog Comparator Output
The output of the Analog Comparator is synchronized and then directly connected to ACO. The
synchronization introduces a delay of 1 - 2 clock cycles.
• Bit 4 – ACI: Analog Comparator Interrupt Flag
This bit is set by hardware when a comparator output event triggers the interrupt mode defined
by ACIS1 and ACIS0. The Analog Comparator interrupt routine is executed if the ACIE bit is set
and the I-bit in SREG is set. ACI is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, ACI is cleared by writing a logic one to the flag.
• Bit 3 – ACIE: Analog Comparator Interrupt Enable
When the ACIE bit is written logic one and the I-bit in the Status Register is set, the Analog Comparator interrupt is activated. When written logic zero, the interrupt is disabled.
• Bit 2 – Res: Reserved Bit
This bit is a reserved bit in the ATtiny13 and will always read as zero.
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• 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 13-2 on page 80.
Table 13-2.
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.
13.2.3
DIDR0 – Digital Input Disable Register 0
Bit
7
6
5
4
3
2
1
0
–
–
ADC0D
ADC2D
ADC3D
ADC1D
AIN1D
AIN0D
Read/Write
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
DIDR0
• Bits 1, 0 – AIN1D, AIN0D: AIN1, AIN0 Digital Input Disable
When this bit is written logic one, the digital input buffer on the AIN1/0 pin is disabled. The corresponding PIN Register bit will always read as zero when this bit is set. When an analog signal is
applied to the AIN1/0 pin and the digital input from this pin is not needed, this bit should be written logic one to reduce power consumption in the digital input buffer.
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14. Analog to Digital Converter
14.1
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
14.2
10-bit Resolution
0.5 LSB Integral Non-linearity
± 2 LSB Absolute Accuracy
13 - 260 µs Conversion Time
Up to 15 kSPS at Maximum Resolution
Four Multiplexed Single Ended Input Channels
Optional Left Adjustment for ADC Result Readout
0 - VCC ADC Input Voltage Range
Selectable 1.1V ADC Reference Voltage
Free Running or Single Conversion Mode
ADC Start Conversion by Auto Triggering on Interrupt Sources
Interrupt on ADC Conversion Complete
Sleep Mode Noise Canceler
Overview
The ATtiny13 features a 10-bit successive approximation ADC. A block diagram of the ADC is
shown in Figure 14-1.
Figure 14-1. Analog to Digital Converter Block Schematic
ADC CONVERSION
COMPLETE IRQ
INTERRUPT
FLAGS
ADTS[2:0]
15
TRIGGER
SELECT
ADC[9:0]
ADPS0
ADPS1
ADPS2
ADIF
ADATE
ADEN
0
ADC DATA REGISTER
(ADCH/ADCL)
ADC CTRL. & STATUS
REGISTER (ADCSRA)
ADSC
MUX0
MUX1
ADLAR
REFS1
ADC MULTIPLEXER
SELECT (ADMUX)
ADIE
ADIF
8-BIT DATA BUS
MUX DECODER
CHANNEL SELECTION
PRESCALER
VCC
START
CONVERSION LOGIC
INTERNAL 1.1V
REFERENCE
SAMPLE & HOLD
COMPARATOR
10-BIT DAC
+
ADC3
ADC2
ADC1
INPUT
MUX
ADC MULTIPLEXER
OUTPUT
ADC0
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The ADC is connected to a 4-channel Analog Multiplexer which allows four single-ended voltage
inputs constructed from the pins of Port B. The single-ended voltage inputs refer to 0V (GND).
The ADC contains a Sample and Hold circuit which ensures that the input voltage to the ADC is
held at a constant level during conversion. Internal reference voltages of nominally 1.1V or VCC
are provided On-chip.
14.3
Operation
The ADC converts an analog input voltage to a 10-bit digital value through successive approximation. The minimum value represents GND and the maximum value represents the voltage on
VCC or an internal 1.1V reference voltage.
The analog input channel is selected by writing to the MUX bits in ADMUX. Any of the ADC input
pins, can be selected as single ended inputs to the ADC.
The ADC is enabled by setting the ADC Enable bit, ADEN in ADCSRA. Voltage reference and
input channel selections will not go into effect until ADEN is set. The ADC does not consume
power when ADEN is cleared, so it is recommended to switch off the ADC before entering power
saving sleep modes.
The ADC generates a 10-bit result which is presented in the ADC Data Registers, ADCH and
ADCL. By default, the result is presented right adjusted, but can optionally be presented left
adjusted by setting the ADLAR bit in ADMUX.
If the result is left adjusted and no more than 8-bit precision is required, it is sufficient to read
ADCH. Otherwise, ADCL must be read first, then ADCH, to ensure that the content of the data
registers belongs to the same conversion. Once ADCL is read, ADC access to data registers is
blocked. This means that if ADCL has been read, and a conversion completes before ADCH is
read, neither register is updated and the result from the conversion is lost. When ADCH is read,
ADC access to the ADCH and ADCL Registers is re-enabled.
The ADC has its own interrupt which can be triggered when a conversion completes. When ADC
access to the data registers is prohibited between reading of ADCH and ADCL, the interrupt will
trigger even if the result is lost.
14.4
Starting a Conversion
A single conversion is started by writing a logical one to the ADC Start Conversion bit, ADSC.
This bit stays high as long as the conversion is in progress and will be cleared 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.
Alternatively, a conversion can be triggered automatically by various sources. Auto Triggering is
enabled by setting the ADC Auto Trigger Enable bit, ADATE in ADCSRA. The trigger source is
selected by setting the ADC Trigger Select bits, ADTS in ADCSRB (see description of the ADTS
bits for a list of the trigger sources). When a positive edge occurs on the selected trigger signal,
the ADC prescaler is reset and a conversion is started. This provides a method of starting conversions at fixed intervals. If the trigger signal still is set when the conversion completes, a new
conversion will not be started. If another positive edge occurs on the trigger signal during conversion, the edge will be ignored. Note that an Interrupt Flag will be set even if the specific
interrupt is disabled or the Global Interrupt Enable bit in SREG is cleared. A conversion can thus
be triggered without causing an interrupt. However, the Interrupt Flag must be cleared in order to
trigger a new conversion at the next interrupt event.
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Figure 14-2. ADC Auto Trigger Logic
ADTS[2:0]
PRESCALER
START
ADIF
CLKADC
ADATE
SOURCE 1
.
.
.
.
CONVERSION
LOGIC
EDGE
DETECTOR
SOURCE n
ADSC
Using the ADC Interrupt Flag as a trigger source makes the ADC start a new conversion as soon
as the ongoing conversion has finished. The ADC then operates in Free Running mode, constantly sampling and updating the ADC Data Register. The first conversion must be started by
writing a logical one to the ADSC bit in ADCSRA. In this mode the ADC will perform successive
conversions independently of whether the ADC Interrupt Flag, ADIF is cleared or not.
If Auto Triggering is enabled, single conversions can be started by writing ADSC in ADCSRA to
one. ADSC can also be used to determine if a conversion is in progress. The ADSC bit will be
read as one during a conversion, independently of how the conversion was started.
14.5
Prescaling and Conversion Timing
By default, the successive approximation circuitry requires an input clock frequency between 50
kHz and 200 kHz to get maximum resolution. If a lower resolution than 10 bits is needed, the
input clock frequency to the ADC can be higher than 200 kHz to get a higher sample rate.
Figure 14-3. ADC Prescaler
ADEN
START
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 module contains a prescaler, which generates an acceptable ADC clock frequency
from any CPU frequency above 100 kHz. The prescaling is set by the ADPS bits in ADCSRA.
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The prescaler starts counting from the moment the ADC is switched on by setting the ADEN bit
in ADCSRA. The prescaler keeps running for as long as the ADEN bit is set, and is continuously
reset when ADEN is low.
When initiating a single ended conversion by setting the ADSC bit in ADCSRA, the conversion
starts at the following rising edge of the ADC clock cycle.
A normal conversion takes 13 ADC clock cycles. The first conversion after the ADC is switched
on (ADEN in ADCSRA is set) takes 25 ADC clock cycles in order to initialize the analog circuitry,
as shown in Figure 14-4 below.
Figure 14-4. ADC Timing Diagram, First Conversion (Single Conversion Mode)
Next
Conversion
First Conversion
Cycle Number
1
2
12
13
14
15
16
17
18
19
20
21
22
23
24
25
1
2
3
ADC Clock
ADEN
ADSC
ADIF
Sign and MSB of Result
ADCH
LSB of Result
ADCL
MUX and REFS
Update
Conversion
Complete
Sample & Hold
MUX and REFS
Update
When the bandgap reference voltage is used as input to the ADC, it will take a certain time for
the voltage to stabilize. If not stabilized, the first value read after the first conversion may be
wrong.
The actual sample-and-hold takes place 1.5 ADC clock cycles after the start of a normal conversion and 14.5 ADC clock cycles after the start of an first conversion. When a conversion is
complete, the result is written to the ADC Data Registers, and ADIF is set. In Single Conversion
mode, ADSC is cleared simultaneously. The software may then set ADSC again, and a new
conversion will be initiated on the first rising ADC clock edge.
Figure 14-5. ADC Timing Diagram, Single Conversion
One Conversion
Cycle Number
1
2
3
4
5
6
7
8
9
Next Conversion
10
11
12
13
1
2
3
ADC Clock
ADSC
ADIF
ADCH
Sign and MSB of Result
ADCL
LSB of Result
Sample & Hold
MUX and REFS
Update
84
Conversion
Complete
MUX and REFS
Update
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ATtiny13
When Auto Triggering is used, the prescaler is reset when the trigger event occurs, as shown in
Figure 14-6 below. This assures a fixed delay from the trigger event to the start of conversion. In
this mode, the sample-and-hold takes place two ADC clock cycles after the rising edge on the
trigger source signal. Three additional CPU clock cycles are used for synchronization logic.
Figure 14-6. ADC Timing Diagram, Auto Triggered Conversion
One Conversion
1
Cycle Number
2
3
4
5
6
7
8
Next Conversion
10
9
11
12
13
1
2
ADC Clock
Trigger
Source
ADATE
ADIF
ADCH
Sign and MSB of Result
ADCL
LSB of Result
Prescaler
Reset
Sample &
Hold
Prescaler
Reset
Conversion
Complete
MUX and REFS
Update
In Free Running mode, a new conversion will be started immediately after the conversion completes, while ADSC remains high.
Figure 14-7. ADC Timing Diagram, Free Running Conversion
One Conversion
Cycle Number
11
12
Next Conversion
13
1
2
3
4
ADC Clock
ADSC
ADIF
ADCH
Sign and MSB of Result
ADCL
LSB of Result
Conversion
Complete
Sample & Hold
MUX and REFS
Update
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For a summary of conversion times, see Table 14-1.
Table 14-1.
ADC Conversion Time
Condition
Conversion Time (Cycles)
First conversion
13.5
25
Normal conversions
1.5
13
2
13.5
Auto Triggered conversions
14.6
Sample & Hold (Cycles
from Start of Conversion)
Changing Channel or Reference Selection
The MUXn and REFS1:0 bits in the ADMUX Register are single buffered through a temporary
register to which the CPU has random access. This ensures that the channels and reference
selection only takes place at a safe point during the conversion. The channel and reference
selection is continuously updated until a conversion is started. Once the conversion starts, the
channel and reference selection is locked to ensure a sufficient sampling time for the ADC. Continuous updating resumes in the last ADC clock cycle before the conversion completes (ADIF in
ADCSRA is set). Note that the conversion starts on the following rising ADC clock edge after
ADSC is written. The user is thus advised not to write new channel or reference selection values
to ADMUX until one ADC clock cycle after ADSC is written.
If Auto Triggering is used, the exact time of the triggering event can be indeterministic. Special
care must be taken when updating the ADMUX Register, in order to control which conversion
will be affected by the new settings.
If both ADATE and ADEN is written to one, an interrupt event can occur at any time. If the
ADMUX Register is changed in this period, the user cannot tell if the next conversion is based
on the old or the new settings. ADMUX can be safely updated in the following ways:
• When ADATE or ADEN is cleared.
• During conversion, minimum one ADC clock cycle after the trigger event.
• After a conversion, before the Interrupt Flag used as trigger source is cleared.
When updating ADMUX in one of these conditions, the new settings will affect the next ADC
conversion.
14.6.1
ADC Input Channels
When changing channel selections, the user should observe the following guidelines to ensure
that the correct channel is selected:
In Single Conversion mode, always select the channel before starting the conversion. The channel selection may be changed one ADC clock cycle after writing one to ADSC. However, the
simplest method is to wait for the conversion to complete before changing the channel selection.
In Free Running mode, always select the channel before starting the first conversion. The channel selection may be changed one ADC clock cycle after writing one to ADSC. However, the
simplest method is to wait for the first conversion to complete, and then change the channel
selection. Since the next conversion has already started automatically, the next result will reflect
the previous channel selection. Subsequent conversions will reflect the new channel selection.
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14.6.2
14.7
ADC Voltage Reference
The reference voltage for the ADC (VREF) indicates the conversion range for the ADC. Single
ended channels that exceed VREF will result in codes close to 0x3FF. VREF can be selected as
either VCC, or internal 1.1V reference. The first ADC conversion result after switching reference
voltage source may be inaccurate, and the user is advised to discard this result.
ADC Noise Canceler
The ADC features a noise canceler that enables conversion during sleep mode to reduce noise
induced from the CPU core and other I/O peripherals. The noise canceler can be used with ADC
Noise Reduction and Idle mode. To make use of this feature, the following procedure should be
used:
• Make sure that the ADC is enabled and is not busy converting. Single Conversion mode must
be selected and the ADC conversion complete interrupt must be enabled.
• Enter ADC Noise Reduction mode (or Idle mode). The ADC will start a conversion once the
CPU has been halted.
• If no other interrupts occur before the ADC conversion completes, the ADC interrupt will wake
up the CPU and execute the ADC Conversion Complete interrupt routine. If another interrupt
wakes up the CPU before the ADC conversion is complete, the interrupt will be executed, and
an ADC Conversion Complete interrupt request will be generated when the ADC conversion
completes. The CPU will remain in active mode until a new sleep command is executed.
Note that the ADC will not be automatically turned off when entering other sleep modes than Idle
mode and ADC Noise Reduction mode. The user is advised to write zero to ADEN before entering such sleep modes to avoid excessive power consumption.
14.8
Analog Input Circuitry
The analog input circuitry for single ended channels is shown in Figure 14-8 An analog source
applied to ADCn is subjected to pin capacitance and input leakage of that pin, regardless if the
channel is chosen as input for the ADC, or not. When the channel is selected, the source drives
the S/H capacitor through the series resistance (combined resistance in input path).
Figure 14-8. Analog Input Circuitry
IIH
n
1..100 kohm
CS/H= 14 pF
IIL
Note:
The capacitor in the figure depicts the total capacitance, including the sample/hold capacitor and
any stray or parasitic capacitance inside the device. The value given is worst case.
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The ADC is optimized for analog signals with an output impedance of approximately 10 kΩ or
less. If such a source is used, the sampling time will be negligible. If a source with higher impedance is used, the sampling time will depend on how long time the source needs to charge the
S/H capacitor, with can vary widely. The user is recommended to only use low impedant sources
with slowly varying signals, since this minimizes the required charge transfer to the S/H
capacitor.
Signal components higher than the Nyquist frequency (fADC/2) should not be present to avoid
distortion from unpredictable signal convolution. The user is advised to remove high frequency
components with a low-pass filter before applying the signals as inputs to the ADC.
14.9
Analog Noise Canceling Techniques
Digital circuitry inside and outside the device generates EMI which might affect the accuracy of
analog measurements. When conversion accuracy is critical, the noise level can be reduced by
applying the following techniques:
• Keep analog signal paths as short as possible.
• Make sure analog tracks run over the analog ground plane.
• Keep analog tracks well away from high-speed switching digital tracks.
• If any port pin is used as a digital output, it mustn’t switch while a conversion is in progress.
• Place bypass capacitors as close to VCC and GND pins as possible.
Where high ADC accuracy is required it is recommended to use ADC Noise Reduction Mode, as
described in Section 14.7 on page 87. This is especially the case when system clock frequency
is above 1 MHz. A good system design with properly placed, external bypass capacitors does
reduce the need for using ADC Noise Reduction Mode
14.10 ADC Accuracy Definitions
An n-bit single-ended ADC converts a voltage linearly between GND and V REF in 2 n steps
(LSBs). The lowest code is read as 0, and the highest code is read as 2n-1.
Several parameters describe the deviation from the ideal behavior:
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• Offset: The deviation of the first transition (0x000 to 0x001) compared to the ideal transition
(at 0.5 LSB). Ideal value: 0 LSB.
Figure 14-9. Offset Error
Output Code
Ideal ADC
Actual ADC
Offset
Error
VREF Input Voltage
• Gain Error: After adjusting for offset, the Gain Error is found as the deviation of the last
transition (0x3FE to 0x3FF) compared to the ideal transition (at 1.5 LSB below maximum).
Ideal value: 0 LSB
Figure 14-10. Gain Error
Output Code
Gain
Error
Ideal ADC
Actual ADC
VREF Input Voltage
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• Integral Non-linearity (INL): After adjusting for offset and gain error, the INL is the maximum
deviation of an actual transition compared to an ideal transition for any code. Ideal value: 0
LSB.
Figure 14-11. Integral Non-linearity (INL)
Output Code
INL
Ideal ADC
Actual ADC
VREF
Input Voltage
• Differential Non-linearity (DNL): The maximum deviation of the actual code width (the interval
between two adjacent transitions) from the ideal code width (1 LSB). Ideal value: 0 LSB.
Figure 14-12. Differential Non-linearity (DNL)
Output Code
0x3FF
1 LSB
DNL
0x000
0
90
VREF Input Voltage
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ATtiny13
• Quantization Error: Due to the quantization of the input voltage into a finite number of codes,
a range of input voltages (1 LSB wide) will code to the same value. Always ± 0.5 LSB.
• Absolute Accuracy: The maximum deviation of an actual (unadjusted) transition compared to
an ideal transition for any code. This is the compound effect of offset, gain error, differential
error, non-linearity, and quantization error. Ideal value: ± 0.5 LSB.
14.11 ADC Conversion Result
After the conversion is complete (ADIF is high), the conversion result can be found in the ADC
Result Registers (ADCL, ADCH).
For single ended conversion, the result is
V IN ⋅ 1024
ADC = -------------------------V REF
where VIN is the voltage on the selected input pin and VREF the selected voltage reference (see
Table 14-2 on page 91 and Table 14-3 on page 92). 0x000 represents analog ground, and
0x3FF represents the selected reference voltage minus one LSB.
14.12 Register Description
14.12.1
ADMUX – ADC Multiplexer Selection Register
Bit
7
6
5
4
3
2
1
0
–
REFS0
ADLAR
–
–
–
MUX1
MUX0
Read/Write
R
R/W
R/W
R
R
R
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
ADMUX
• Bit 7 – Res: Reserved Bit
This bit is reserved bit in the ATtiny13 and will always read as zero.
• Bit 6 – REFS0: Reference Selection Bit
This bit selects the voltage reference for the ADC, as shown in Table 14-2. If this bit is changed
during a conversion, the change will not go in effect until this conversion is complete (ADIF in
ADCSRA is set).
Table 14-2.
Voltage Reference Selections for ADC
REFS0
Voltage Reference Selection
0
VCC used as analog reference.
1
Internal Voltage Reference.
• Bit 5 – ADLAR: ADC Left Adjust Result
The ADLAR bit affects the presentation of the ADC conversion result in the ADC Data Register.
Write one to ADLAR to left adjust the result. Otherwise, the result is right adjusted. Changing the
ADLAR bit will affect the ADC Data Register immediately, regardless of any ongoing conversions. For a complete description of this bit, see “ADCL and ADCH – The ADC Data Register” on
page 93.
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• Bits 4:2 – Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and will always read as zero.
• Bits 1:0 – MUX1:0: Analog Channel Selection Bits
The value of these bits selects which combination of analog inputs are connected to the ADC.
See Table 14-3 on page 92 for details. If these bits are changed during a conversion, the change
will not go in effect until this conversion is complete (ADIF in ADCSRA is set).
Table 14-3.
Input Channel Selections
MUX1..0
14.12.2
Single Ended Input
00
ADC0 (PB5)
01
ADC1 (PB2)
10
ADC2 (PB4)
11
ADC3 (PB3)
ADCSRA – ADC Control and Status Register A
Bit
7
6
5
4
3
2
1
0
ADEN
ADSC
ADATE
ADIF
ADIE
ADPS2
ADPS1
ADPS0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
ADCSRA
• Bit 7 – ADEN: ADC Enable
Writing this bit to one enables the ADC. By writing it to zero, the ADC is turned off. Turning the
ADC off while a conversion is in progress, will terminate this conversion.
• Bit 6 – ADSC: ADC Start Conversion
In Single Conversion mode, write this bit to one to start each conversion. In Free Running mode,
write this bit to one to start the first conversion. The first conversion after ADSC has been written
after the ADC has been enabled, or if ADSC is written at the same time as the ADC is enabled,
will take 25 ADC clock cycles instead of the normal 13. This first conversion performs initialization of the ADC.
ADSC will read as one as long as a conversion is in progress. When the conversion is complete,
it returns to zero. Writing zero to this bit has no effect.
• Bit 5 – ADATE: ADC Auto Trigger Enable
When this bit is written to one, Auto Triggering of the ADC is enabled. The ADC will start a conversion on a positive edge of the selected trigger signal. The trigger source is selected by setting
the ADC Trigger Select bits, ADTS in ADCSRB.
• Bit 4 – ADIF: ADC Interrupt Flag
This bit is set when an ADC conversion completes and the data registers are updated. The ADC
Conversion Complete Interrupt is executed if the ADIE bit and the I-bit in SREG are set. ADIF is
cleared by hardware when executing the corresponding interrupt handling vector. Alternatively,
ADIF is cleared by writing a logical one to the flag. Beware that if doing a Read-Modify-Write on
ADCSRA, a pending interrupt can be disabled. This also applies if the SBI and CBI instructions
are used.
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• Bit 3 – ADIE: ADC Interrupt Enable
When this bit is written to one and the I-bit in SREG is set, the ADC Conversion Complete Interrupt is activated.
• Bits 2:0 – ADPS2:0: ADC Prescaler Select Bits
These bits determine the division factor between the system clock frequency and the input clock
to the ADC.
Table 14-4.
14.12.3
ADC Prescaler Selections
ADPS2
ADPS1
ADPS0
Division Factor
0
0
0
2
0
0
1
2
0
1
0
4
0
1
1
8
1
0
0
16
1
0
1
32
1
1
0
64
1
1
1
128
ADCL and ADCH – The ADC Data Register
14.12.3.1
ADLAR = 0
Bit
Read/Write
Initial Value
14.12.3.2
15
14
13
12
11
10
9
8
–
–
–
–
–
–
ADC9
ADC8
ADCH
ADC7
ADC6
ADC5
ADC4
ADC3
ADC2
ADC1
ADC0
ADCL
7
6
5
4
3
2
1
0
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
ADLAR = 1
Bit
Read/Write
Initial Value
15
14
13
12
11
10
9
8
ADC9
ADC8
ADC7
ADC6
ADC5
ADC4
ADC3
ADC2
ADCH
ADC1
ADC0
–
–
–
–
–
–
ADCL
7
6
5
4
3
2
1
0
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
When an ADC conversion is complete, the result is found in these two registers.
When ADCL is read, the ADC Data Register is not updated until ADCH is read. Consequently, if
the result is left adjusted and no more than 8-bit precision is required, it is sufficient to read
ADCH. Otherwise, ADCL must be read first, then ADCH.
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The ADLAR bit in ADMUX, and the MUXn bits in ADMUX affect the way the result is read from
the registers. If ADLAR is set, the result is left adjusted. If ADLAR is cleared (default), the result
is right adjusted.
• ADC9:0: ADC Conversion Result
These bits represent the result from the conversion, as detailed in “ADC Conversion Result” on
page 91.
14.12.4
ADCSRB – ADC Control and Status Register B
Bit
7
6
5
4
3
2
1
0
–
ACME
–
–
–
ADTS2
ADTS1
ADTS0
Read/Write
R
R/W
R
R
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
ADCSRB
• Bits 7, 5:3 – Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and will always read as zero.
• Bits 2:0 – ADTS2:0: ADC Auto Trigger Source
If ADATE in ADCSRA is written to one, the value of these bits selects which source will trigger
an ADC conversion. If ADATE is cleared, the ADTS2:0 settings will have no effect. A conversion
will be triggered by the rising edge of the selected Interrupt Flag. Note that switching from a trigger source that is cleared to a trigger source that is set, will generate a positive edge on the
trigger signal. If ADEN in ADCSRA is set, this will start a conversion. Switching to Free Running
mode (ADTS[2:0]=0) will not cause a trigger event, even if the ADC Interrupt Flag is set.
Table 14-5.
14.12.5
ADC Auto Trigger Source Selections
ADTS2
ADTS1
ADTS0
Trigger Source
0
0
0
Free Running mode
0
0
1
Analog Comparator
0
1
0
External Interrupt Request 0
0
1
1
Timer/Counter Compare Match A
1
0
0
Timer/Counter Overflow
1
0
1
Timer/Counter Compare Match B
1
1
0
Pin Change Interrupt Request
DIDR0 – Digital Input Disable Register 0
Bit
7
6
5
4
3
2
1
0
–
–
ADC0D
ADC2D
ADC3D
ADC1D
AIN1D
AIN0D
Read/Write
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
DIDR0
• Bits 5:2 – ADC3D:ADC0D: ADC3:0 Digital Input Disable
When a bit is written logic one, the digital input buffer on the corresponding ADC pin is disabled.
The corresponding PIN register bit will always read as zero when this bit is set. When an analog
signal is applied to the ADC7..0 pin and the digital input from this pin is not needed, this bit
should be written logic one to reduce power consumption in the digital input buffer.
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15. debugWIRE On-chip Debug System
15.1
Features
•
•
•
•
•
•
•
•
•
•
15.2
Complete Program Flow Control
Emulates All On-chip Functions, Both Digital and Analog, except RESET Pin
Real-time Operation
Symbolic Debugging Support (Both at C and Assembler Source Level, or for Other HLLs)
Unlimited Number of Program Break Points (Using Software Break Points)
Non-intrusive Operation
Electrical Characteristics Identical to Real Device
Automatic Configuration System
High-Speed Operation
Programming of Non-volatile Memories
Overview
The debugWIRE On-chip debug system uses a One-wire, bi-directional interface to control the
program flow, execute AVR instructions in the CPU and to program the different non-volatile
memories.
15.3
Physical Interface
When the debugWIRE Enable (DWEN) fuse is programmed and lock bits are unprogrammed,
the debugWIRE system within the target device is activated. The RESET port pin is configured
as a wire-AND (open-drain) bi-directional I/O pin with pull-up enabled and becomes the communication gateway between target and emulator.
Figure 15-1 shows the schematic of a target MCU, with debugWIRE enabled, and the emulator
connector. The system clock is not affected by debugWIRE and will always be the clock source
selected by the CKSEL fuses.
Figure 15-1. The debugWIRE Setup
1.8 - 5.5V
VCC
dW
dW(RESET)
GND
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When designing a system where debugWIRE will be used, the following must be observed:
• Pull-Up resistor on the dW/(RESET) line must be in the range of 10k to 20 kΩ. However, the
pull-up resistor is optional.
• Connecting the RESET pin directly to VCC will not work.
• Capacitors inserted on the RESET pin must be disconnected when using debugWire.
• All external reset sources must be disconnected.
15.4
Software Break Points
debugWIRE supports Program memory Break Points by the AVR Break instruction. Setting a
Break Point in AVR Studio® will insert a BREAK instruction in the Program memory. The instruction replaced by the BREAK instruction will be stored. When program execution is continued, the
stored instruction will be executed before continuing from the Program memory. A break can be
inserted manually by putting the BREAK instruction in the program.
The Flash must be re-programmed each time a Break Point is changed. This is automatically
handled by AVR Studio through the debugWIRE interface. The use of Break Points will therefore
reduce the Flash Data retention. Devices used for debugging purposes should not be shipped to
end customers.
15.5
Limitations of debugWIRE
The debugWIRE communication pin (dW) is physically located on the same pin as External
Reset (RESET). An External Reset source is therefore not supported when the debugWIRE is
enabled.
The debugWIRE system accurately emulates all I/O functions when running at full speed, i.e.,
when the program in the CPU is running. When the CPU is stopped, care must be taken while
accessing some of the I/O Registers via the debugger (AVR Studio). See the debugWIRE documentation for detailed description of the limitations.
The debugWIRE interface is asynchronous, which means that the debugger needs to synchronize to the system clock. If the system clock is changed by software (e.g. by writing CLKPS bits)
communication via debugWIRE may fail. Also, clock frequencies below 100 kHz may cause
communication problems.
A programmed DWEN fuse enables some parts of the clock system to be running in all sleep
modes. This will increase the power consumption while in sleep. Thus, the DWEN fuse should
be disabled when debugWire is not used.
15.6
Register Description
The following section describes the registers used with the debugWire.
15.6.1
DWDR –debugWire Data Register
Bit
7
6
5
4
3
2
1
0
DWDR[7:0]
DWDR
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
The DWDR Register provides a communication channel from the running program in the MCU
to the debugger. This register is only accessible by the debugWIRE and can therefore not be
used as a general purpose register in the normal operations.
96
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ATtiny13
16. Self-Programming the Flash
The device provides a Self-Programming mechanism for downloading and uploading program
code by the MCU itself. The Self-Programming can use any available data interface and associated protocol to read code and write (program) that code into the Program memory. The SPM
instruction is disabled by default but it can be enabled by programming the SELFPRGEN fuse
(to “0”).
The Program memory is updated in a page by page fashion. Before programming a page with
the data stored in the temporary page buffer, the page must be erased. The temporary page
buffer is filled one word at a time using SPM and the buffer can be filled either before the Page
Erase command or between a Page Erase and a Page Write operation:
Alternative 1, fill the buffer before a Page Erase
• Fill temporary page buffer
• Perform a Page Erase
• Perform a Page Write
Alternative 2, fill the buffer after Page Erase
• Perform a Page Erase
• Fill temporary page buffer
• Perform a Page Write
If only a part of the page needs to be changed, the rest of the page must be stored (for example
in the temporary page buffer) before the erase, and then be re-written. When using alternative 1,
the Boot Loader provides an effective Read-Modify-Write feature which allows the user software
to first read the page, do the necessary changes, and then write back the modified data. If alternative 2 is used, it is not possible to read the old data while loading since the page is already
erased. The temporary page buffer can be accessed in a random sequence. It is essential that
the page address used in both the Page Erase and Page Write operation is addressing the same
page.
16.1
Performing Page Erase by SPM
To execute Page Erase, set up the address in the Z-pointer, write “00000011” to SPMCSR and
execute SPM within four clock cycles after writing SPMCSR. The data in R1 and R0 is ignored.
The page address must be written to PCPAGE in the Z-register. Other bits in the Z-pointer will
be ignored during this operation.
Note:
16.2
The CPU is halted during the Page Erase operation.
Filling the Temporary Buffer (Page Loading)
To write an instruction word, set up the address in the Z-pointer and data in R1:R0, write
“00000001” to SPMCSR and execute SPM within four clock cycles after writing SPMCSR. The
content of PCWORD in the Z-register is used to address the data in the temporary buffer. The
temporary buffer will auto-erase after a Page Write operation or by writing the CTPB bit in
SPMCSR. It is also erased after a system reset. Note that it is not possible to write more than
one time to each address without erasing the temporary buffer.
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If the EEPROM is written in the middle of an SPM Page Load operation, all data loaded will be
lost.
16.3
Performing a Page Write
To execute Page Write, set up the address in the Z-pointer, write “00000101” to SPMCSR and
execute SPM within four clock cycles after writing SPMCSR. The data in R1 and R0 is ignored.
The page address must be written to PCPAGE. Other bits in the Z-pointer must be written to
zero during this operation.
Note:
16.4
The CPU is halted during the Page Write operation.
Addressing the Flash During Self-Programming
The Z-pointer is used to address the SPM commands.
Bit
15
14
13
12
11
10
9
8
ZH (R31)
Z15
Z14
Z13
Z12
Z11
Z10
Z9
Z8
ZL (R30)
Z7
Z6
Z5
Z4
Z3
Z2
Z1
Z0
7
6
5
4
3
2
1
0
Since the Flash is organized in pages (see Table 17-5 on page 104), the Program Counter can
be treated as having two different sections. One section, consisting of the least significant bits, is
addressing the words within a page, while the most significant bits are addressing the pages.
This is shown in Figure 16-1. Note that the Page Erase and Page Write operations are
addressed independently. Therefore it is of major importance that the software addresses the
same page in both the Page Erase and Page Write operation.
Figure 16-1. Addressing the Flash During SPM(1)
BIT
15
ZPCMSB
ZPAGEMSB
Z - REGISTER
1 0
0
PCMSB
PROGRAM
COUNTER
PAGEMSB
PCPAGE
PAGE ADDRESS
WITHIN THE FLASH
PROGRAM MEMORY
PAGE
PCWORD
WORD ADDRESS
WITHIN A PAGE
PAGE
INSTRUCTION WORD
PCWORD[PAGEMSB:0]:
00
01
02
PAGEEND
Note:
98
1. The variables used in Figure 16-1 are listed in Table 17-5 on page 104.
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ATtiny13
The LPM instruction uses the Z-pointer to store the address. Since this instruction addresses the
Flash byte-by-byte, also the LSB (bit Z0) of the Z-pointer is used.
16.5
EEPROM Write Prevents Writing to SPMCSR
Note that an EEPROM write operation will block all software programming to Flash. Reading the
fuses and lock bits from software will also be prevented during the EEPROM write operation. It is
recommended that the user checks the status bit (EEPE) in the EECR Register and verifies that
the bit is cleared before writing to the SPMCSR Register.
16.6
Reading Fuse and Lock Bits from Firmware
It is possible to read fuse and lock bits from software.
16.6.1
Reading Lock Bits from Firmware
Issuing an LPM instruction within three CPU cycles after RFLB and SELFPRGEN bits have
been set in SPMCSR will return lock bit values in the destination register. The RFLB and SELFPRGEN bits automatically clear upon completion of reading the lock bits, or if no LPM instruction
is executed within three CPU cycles, or if no SPM instruction is executed within four CPU cycles.
When RFLB and SELFPRGEN are cleared, LPM functions normally.
To read the lock bits, follow the below procedure.
1. Load the Z-pointer with 0x0001.
2. Set RFLB and SELFPRGEN bits in SPMCSR.
3. Issuing an LPM instruction within three clock cycles will return lock bits in the destination register.
If successful, the contents of the destination register are as follows.
Bit
7
6
5
4
3
2
1
0
Rd
–
–
–
–
–
–
LB2
LB1
See section “Program And Data Memory Lock Bits” on page 102 for more information on lock
bits.
16.6.2
Reading Fuse Bits from Firmware
The algorithm for reading fuse bytes is similar to the one described above for reading lock bits,
only the addresses are different.
To read the Fuse Low Byte (FLB), follow the below procedure:
1. Load the Z-pointer with 0x0000.
2. Set RFLB and SELFPRGEN bits in SPMCSR.
3. Issuing an LPM instruction within three clock cycles will FLB in the destination register.
If successful, the contents of the destination register are as follows.
Bit
7
6
5
4
3
2
1
0
Rd
FLB7
FLB6
FLB5
FLB4
FLB3
FLB2
FLB1
FLB0
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To read the Fuse High Byte (FHB), simply replace the address in the Z-pointer with 0x0003 and
repeat the procedure above.
If successful, the contents of the destination register are as follows.
Bit
7
6
5
4
3
2
1
0
Rd
FHB7
FHB6
FHB5
FHB4
FHB3
FHB2
FHB1
FHB0
See sections “Program And Data Memory Lock Bits” on page 102 and “Fuse Bytes” on page 103
for more information on fuse and lock bits.
16.7
Preventing Flash Corruption
During periods of low VCC, the Flash program can be corrupted because the supply voltage is
too low for the CPU and the Flash to operate properly. These issues are the same as for board
level systems using the Flash, and the same design solutions should be applied.
A Flash program corruption can be caused by two situations when the voltage is too low. First, a
regular write sequence to the Flash requires a minimum voltage to operate correctly. Secondly,
the CPU itself can execute instructions incorrectly, if the supply voltage for executing instructions
is too low.
Flash corruption can easily be avoided by following these design recommendations (one is
sufficient):
1. Keep the AVR RESET active (low) during periods of insufficient power supply voltage.
This can be done by enabling the internal Brown-out Detector (BOD) if the operating
voltage matches the detection level. If not, an external low VCC reset protection circuit
can be used. If a reset occurs while a write operation is in progress, the write operation
will be completed provided that the power supply voltage is sufficient.
2. Keep the AVR core in Power-down sleep mode during periods of low VCC. This will prevent the CPU from attempting to decode and execute instructions, effectively protecting
the SPMCSR Register and thus the Flash from unintentional writes.
16.8
Programming Time for Flash when Using SPM
The calibrated RC Oscillator is used to time Flash accesses. Table 16-1 on page 100 shows the
typical programming time for Flash accesses from the CPU.
Table 16-1.
Symbol
Min Programming Time
Max Programming Time
Flash write (Page Erase, Page Write, and
write lock bits by SPM)
3.7 ms
4.5 ms
Note:
100
SPM Programming Time(1)
1. The min and max programming times is per individual operation.
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ATtiny13
16.9
16.9.1
Register Description
SPMCSR – Store Program Memory Control and Status Register
The Store Program Memory Control and Status Register contains the control bits needed to control the Program memory operations.
Bit
7
6
5
4
3
2
1
0
–
–
–
CTPB
RFLB
PGWRT
PGERS
SELFPRGEN
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
SPMCSR
• Bits 7..5 – Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and always read as zero.
• Bit 4 – CTPB: Clear Temporary Page Buffer
If the CTPB bit is written while filling the temporary page buffer, the temporary page buffer will be
cleared and the data will be lost.
• Bit 3 – RFLB: Read Fuse and Lock Bits
An LPM instruction within three cycles after RFLB and SELFPRGEN are set in the SPMCSR
Register, will read either the lock bits or the fuse bits (depending on Z0 in the Z-pointer) into the
destination register. See “EEPROM Write Prevents Writing to SPMCSR” on page 99 for details.
• Bit 2 – PGWRT: Page Write
If this bit is written to one at the same time as SELFPRGEN, the next SPM instruction within four
clock cycles executes Page Write, with the data stored in the temporary buffer. The page
address is taken from the high part of the Z-pointer. The data in R1 and R0 are ignored. The
PGWRT bit will auto-clear upon completion of a Page Write, or if no SPM instruction is executed
within four clock cycles. The CPU is halted during the entire Page Write operation.
• Bit 1 – PGERS: Page Erase
If this bit is written to one at the same time as SELFPRGEN, the next SPM instruction within four
clock cycles executes Page Erase. The page address is taken from the high part of the Zpointer. The data in R1 and R0 are ignored. The PGERS bit will auto-clear upon completion of a
Page Erase, or if no SPM instruction is executed within four clock cycles. The CPU is halted during the entire Page Write operation.
• Bit 0 – SELFPRGEN: Self Programming Enable
This bit enables the SPM instruction for the next four clock cycles. If written to one together with
either CTPB, RFLB, PGWRT, or PGERS, the following SPM instruction will have a special
meaning, see description above. If only SELFPRGEN is written, the following SPM instruction
will store the value in R1:R0 in the temporary page buffer addressed by the Z-pointer. The LSB
of the Z-pointer is ignored. The SELFPRGEN bit will auto-clear upon completion of an SPM
instruction, or if no SPM instruction is executed within four clock cycles. During Page Erase and
Page Write, the SELFPRGEN bit remains high until the operation is completed.
Writing any other combination than “10001”, “01001”, “00101”, “00011” or “00001” in the lower
five bits will have no effect.
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17. Memory Programming
This section describes how ATtiny13 memories can be programmed.
17.1
Program And Data Memory Lock Bits
ATtiny13 provides two lock bits which can be left unprogrammed (“1”) or can be programmed
(“0”) to obtain the additional security listed in Table 17-2 on page 102. The lock bits can be
erased to “1” with the Chip Erase command, only.
Program memory can be read out via the debugWIRE interface when the DWEN fuse is programmed, even if the lock bits are set. Thus, when lock bit security is required, debugWIRE
should always be disabled by clearing the DWEN fuse.
Table 17-1.
Lock Bit Byte
Description
Default Value (1)
7
–
1 (unprogrammed)
6
–
1 (unprogrammed)
5
–
1 (unprogrammed)
4
–
1 (unprogrammed)
3
–
1 (unprogrammed)
2
–
1 (unprogrammed)
LB2
1
Lock bit
1 (unprogrammed)
LB1
0
Lock bit
1 (unprogrammed)
Lock Bit Byte
Note:
Bit No
1. “1” means unprogrammed, “0” means programmed
Table 17-2.
Lock Bit Protection Modes
Memory Lock Bits (1) (2)
LB Mode
LB2
LB1
1
1
1
No memory lock features enabled.
0
Further programming of the Flash and EEPROM is disabled in
High-voltage and Serial Programming mode. Fuse bits are
locked in both Serial and High-voltage Programming mode.
debugWire is disabled.
0
Further programming and verification of the Flash and
EEPROM is disabled in High-voltage and Serial Programming
mode. Fuse bits are locked in both Serial and High-voltage
Programming mode. debugWire is disabled.
2
3
Notes:
102
1
0
Protection Type
1. Program fuse bits before lock bits. See section “Fuse Bytes” on page 103.
2. “1” means unprogrammed, “0” means programmed
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ATtiny13
17.2
Fuse Bytes
The ATtiny13 has two fuse bytes. Table 17-3 on page 103 and Table 17-4 on page 103 describe
briefly the functionality of all the fuses and how they are mapped into the fuse bytes. Note that
the fuses are read as logical zero, “0”, if they are programmed.
Table 17-3.
Fuse High Byte
Fuse Bit
Bit No
Description
Default Value
–
7
–
1 (unprogrammed)
–
6
–
1 (unprogrammed)
–
5
–
1 (unprogrammed)
SELFPRGEN(1)
4
Self Programming Enable
1 (unprogrammed)
(2)
3
debugWire Enable
1 (unprogrammed)
(3)
2
Brown-out Detector trigger level
1 (unprogrammed)
(3)
BODLEVEL0
1
Brown-out Detector trigger level
1 (unprogrammed)
RSTDISBL(4)
0
External Reset disable
1 (unprogrammed)
DWEN
BODLEVEL1
Notes:
1. Enables SPM instruction. See “Self-Programming the Flash” on page 97.
2. DWEN must be unprogrammed when lock Bit security is required. See “Program And Data
Memory Lock Bits” on page 102.
3. See Table 18-5 on page 119 for BODLEVEL fuse decoding.
4. See “Alternate Functions of Port B” on page 54 for description of RSTDISBL and DWEN fuses.
When programming the RSTDISBL fuse, High-voltage Serial programming has to be used to
change fuses to perform further programming.
Table 17-4.
Fuse Low Byte
Fuse Bit
Bit No
Description
Default Value
SPIEN(1)
7
Enable Serial Programming and Data
Downloading
0 (programmed)
(SPI prog. enabled)
EESAVE
6
Preserve EEPROM memory through
Chip Erase
1 (unprogrammed)
(memory not preserved)
WDTON(2)
5
Watchdog Timer always on
1 (unprogrammed)
(3)
CKDIV8
4
Divide clock by 8
0 (programmed)
SUT1(4)
3
Select start-up time
1 (unprogrammed)
(4)
2
Select start-up time
0 (programmed)
CKSEL1
(5)
1
Select Clock source
1 (unprogrammed)
CKSEL0
(5)
0
Select Clock source
0 (programmed)
SUT0
Notes:
1. The SPIEN fuse is not accessible in SPI Programming mode.
2. Programming this fues will disable the Watchdog Timer Interrupt. See “Watchdog Timer” on
page 37 for details.
3. See “System Clock Prescaler” on page 26 for details.
4. The default value of SUT1..0 results in maximum start-up time for the default clock source.
See Table 18-3 on page 118 for details.
5. The default setting of CKSEL1..0 results in internal RC Oscillator @ 9.6 MHz. See Table 18-3
on page 118 for details.
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Note that fuse bits are locked if Lock Bit 1 (LB1) is programmed. Program the fuse bits before
programming the lock bits. The status of the fuse bits is not affected by Chip Erase.
Fuse bits can also be read by the device firmware. See section “Reading Fuse and Lock Bits
from Firmware” on page 99.
17.2.1
17.3
Latching of Fuses
The fuse values are latched when the device enters programming mode and changes of the
fuse values will have no effect until the part leaves Programming mode. This does not apply to
the EESAVE fuse which will take effect once it is programmed. The fuses are also latched on
Power-up in Normal mode.
Calibration Bytes
The signature area of the ATtiny13 contains two bytes of calibration data for the internal oscillator. The calibration data in the high byte of address 0x00 is for use with the oscillator set to 9.6
MHz operation. During reset, this byte is automatically written into the OSCCAL register to
ensure correct frequency of the oscillator.
There is a separate calibration byte for the internal oscillator in 4.8 MHz mode of operation but
this data is not loaded automatically. The hardware always loads the 9.6 MHz calibraiton data
during reset. To use separate calibration data for the oscillator in 4.8 MHz mode the OSCCAL
register must be updated by firmware. The calibration data for 4.8 MHz operation is located in
the high byte at address 0x01 of the signature area.
17.4
Signature Bytes
All Atmel microcontrollers have a three-byte signature code which identifies the device. This
code can be read in both serial and high-voltage programming mode, even when the device is
locked. The three bytes reside in a separate address space.
For the ATtiny13 the signature bytes are:
• 0x000: 0x1E (indicates manufactured by Atmel).
• 0x001: 0x90 (indicates 1 KB Flash memory).
• 0x002: 0x07 (indicates ATtiny13 device when 0x001 is 0x90).
17.5
Page Size
Table 17-5.
No. of Words in a Page and No. of Pages in the Flash
Flash Size
512 words (1K byte)
Table 17-6.
104
Page Size
PCWORD
No. of Pages
PCPAGE
PCMSB
16 words
PC[3:0]
32
PC[8:4]
8
No. of Words in a Page and No. of Pages in the EEPROM
EEPROM Size
Page Size
PCWORD
No. of Pages
PCPAGE
EEAMSB
64 bytes
4 bytes
EEA[1:0]
16
EEA[5:2]
5
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ATtiny13
17.6
Serial Programming
Both the Flash and EEPROM memory arrays can be programmed using the serial SPI bus while
RESET is pulled to GND. The serial interface consists of pins SCK, MOSI (input) and MISO (output). See Figure 17-1.
Figure 17-1. Serial Programming and Verify
+1.8 - 5.5V
RESET
PB5
GND
Note:
VCC
PB2
SCK
PB1
MISO
PB0
MOSI
If clocked by internal oscillator there is no need to connect a clock source to the CLKI pin.
After RESET is set low, the Programming Enable instruction needs to be executed first before
program/erase operations can be executed.
Table 17-7.
Note:
Pin Mapping Serial Programming
Symbol
Pins
I/O
Description
MOSI
PB0
I
Serial Data in
MISO
PB1
O
Serial Data out
SCK
PB2
I
Serial Clock
In Table 17-7 above, the pin mapping for SPI programming is listed. Not all parts use the SPI pins
dedicated for the internal SPI interface.
When programming the EEPROM, an auto-erase cycle is built into the self-timed programming
operation (in the Serial mode ONLY) and there is no need to first execute the Chip Erase
instruction. The Chip Erase operation turns the content of every memory location in both the
Program and EEPROM arrays into 0xFF.
Depending on CKSEL fuses, a valid clock must be present. The minimum low and high periods
for the serial clock (SCK) input are defined as follows:
Low: > 2 CPU clock cycles for fck < 12 MHz, 3 CPU clock cycles for fck >= 12 MHz
High: > 2 CPU clock cycles for fck < 12 MHz, 3 CPU clock cycles for fck >= 12 MHz
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17.6.1
Serial Programming Algorithm
When writing serial data to the ATtiny13, data is clocked on the rising edge of SCK.
When reading data from the ATtiny13, data is clocked on the falling edge of SCK. See Figure
18-5 on page 121 and Figure 18-4 on page 121 for timing details.
To program and verify the ATtiny13 in the Serial Programming mode, the following sequence is
recommended (see four byte instruction formats in Table 17-9 on page 107):
1. Power-up sequence:
Apply power between VCC and GND while RESET and SCK are set to “0”. In some systems, the programmer can not guarantee that SCK is held low during power-up. In this
case, RESET must be given a positive pulse after SCK has been set to “0”. The pulse
duration must be at least tRST (miniumum pulse widht of RESET pin, see Table 18-4 on
page 119) plus two CPU clock cycles.
2. Wait for at least 20 ms and enable serial programming by sending the Programming
Enable serial instruction to pin MOSI.
3. The serial programming instructions will not work if the communication is out of synchronization. When in sync. the second byte (0x53), 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 0x53 did not echo back, give
RESET a positive pulse and issue a new Programming Enable command.
4. The Flash is programmed one page at a time. The memory page is loaded one byte at
a time by supplying the 4 LSB of the address and data together with the Load Program
memory Page instruction. To ensure correct loading of the page, the data low byte must
be loaded before data high byte is applied for a given address. The Program memory
Page is stored by loading the Write Program memory Page instruction with the 5 MSB
of the address. If polling (RDY/BSY) is not used, the user must wait at least tWD_FLASH
before issuing the next page. (See Table 17-8 on page 107.) Accessing the serial programming interface before the Flash write operation completes can result in incorrect
programming.
5. A: 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 (RDY/BSY) is not used,
the user must wait at least tWD_EEPROM before issuing the next byte. (See Table 17-8 on
page 107.) In a chip erased device, no 0xFFs in the data file(s) need to be programmed.
B: The EEPROM array is programmed one page at a time. The Memory page is loaded
one byte at a time by supplying the 2 LSB of the address and data together with the
Load EEPROM Memory Page instruction. The EEPROM Memory Page is stored by
loading the Write EEPROM Memory Page Instruction with the 4 MSB of the address.
When using EEPROM page access only byte locations loaded with the Load EEPROM
Memory Page instruction is altered. The remaining locations remain unchanged. If polling (RDY/BSY) is not used, the used must wait at least tWD_EEPROM before issuing the
next page (See Table 17-6 on page 104). In a chip erased device, no 0xFF in the data
file(s) need to be programmed.
6. Any memory location can be verified by using the Read instruction which returns the
content at the selected address at serial output MISO.
7. At the end of the programming session, RESET can be set high to commence normal
operation.
8. Power-off sequence (if needed):
Set RESET to “1”.
Turn VCC power off.
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ATtiny13
.
Table 17-8.
17.6.2
Minimum Wait Delay Before Writing the Next Flash or EEPROM Location
Symbol
Minimum Wait Delay
tWD_FLASH
4.5 ms
tWD_EEPROM
4.0 ms
tWD_ERASE
4.0 ms
tWD_FUSE
4.5 ms
Serial Programming Instruction set
The instruction set is described in Table 17-9.
Table 17-9.
Serial Programming Instruction Set
Instruction Format
Instruction
Byte 1
Byte 2
Byte 3
Byte4
Operation
Programming Enable
1010 1100
0101 0011
xxxx xxxx
xxxx xxxx
Enable Serial Programming after
RESET goes low.
Chip Erase
1010 1100
100x xxxx
xxxx xxxx
xxxx xxxx
Chip Erase EEPROM and Flash.
Read Program Memory
0010 H000
0000 000a
bbbb bbbb
oooo oooo
Read H (high or low) data o from
Program memory at word address a:b.
Write H (high or low) data i to Program
memory page at word address b. Data
low byte must be loaded before Data
high byte is applied within the same
address.
Load Program Memory Page
0100 H000
000x xxxx
xxxx bbbb
iiii iiii
Write Program Memory Page
0100 1100
0000 000a
bbbb xxxx
xxxx xxxx
Read EEPROM Memory
1010 0000
000x xxxx
xxbb bbbb
oooo oooo
Write EEPROM Memory
1100 0000
000x xxxx
xxbb bbbb
iiii iiii
Write data i to EEPROM memory at
address b.
Load EEPROM Memory
Page (page access)
1100 0001
0000 0000
0000 00bb
iiii iiii
Load data i to EEPROM memory page
buffer. After data is loaded, program
EEPROM page.
Write EEPROM Memory
Page (page access)
1100 0010
00xx xxxx
xxbb bb00
xxxx xxxx
Read Lock Bits
0101 1000
0000 0000
xxxx xxxx
xxoo oooo
Read lock bits. “0” = programmed, “1”
= unprogrammed. See Table 17-1 on
page 102 for details.
Write Lock Bits
1010 1100
111x xxxx
xxxx xxxx
11ii iiii
Write lock bits. Set bits = “0” to
program lock bits. See Table 17-1 on
page 102 for details.
Write Program memory Page at
address a:b.
Read data o from EEPROM memory at
address b.
Write EEPROM page at address b.
107
2535I–AVR–05/08
Table 17-9.
Serial Programming Instruction Set (Continued)
Instruction Format
Instruction
Byte 1
Byte 2
Byte 3
Byte4
Operation
Read fuse low/high byte. Bit “0” =
programmed, “1” = unprogrammed.
See “Fuse Bytes” on page 103 for
details.
Read Fuse Byte
0101 H000
0000 H000
xxxx xxxx
oooo oooo
Write Fuse Byte
1010 1100
1010 H000
xxxx xxxx
iiii iiii
Read Signature Byte
0011 0000
000x xxxx
xxxx xxbb
oooo oooo
Read Signature Byte o at address b.
Read Calibration Byte
0011 1000
000x xxxx
0000 000b
oooo oooo
Read Calibration Byte. See
“Calibration Bytes” on page 104
Poll RDY/BSY
1111 0000
0000 0000
xxxx xxxx
xxxx xxxo
Set fuse low/high byte. Set bit to “0” to
program, “1” to unprogram. See “Fuse
Bytes” on page 103 for details.
If o = “1”, a programming operation is
still busy. Wait until this bit returns to
“0” before applying another command.
Note:
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
17.7
High-Voltage Serial Programming
This section describes how to program and verify Flash Program memory, EEPROM Data memory, lock bits and fuse bits in the ATtiny13.
Figure 17-2. High-voltage Serial Programming
+11.5 - 12.5V
SCI
+1.8 - 5.5V
PB5 (RESET)
VCC
PB3
PB2
SDO
PB1
SII
PB0
SDI
GND
108
ATtiny13
2535I–AVR–05/08
ATtiny13
Table 17-10. Pin Name Mapping
Signal Name in High-voltage
Serial Programming Mode
Pin Name
I/O
Function
SDI
PB0
I
Serial Data Input
SII
PB1
I
Serial Instruction Input
SDO
PB2
O
Serial Data Output
SCI
PB3
I
Serial Clock Input (min. 220ns period)
The minimum period for the Serial Clock Input (SCI) during High-voltage Serial Programming is
220 ns.
Table 17-11. Pin Values Used to Enter Programming Mode
17.7.1
Pin
Symbol
Value
SDI
Prog_enable[0]
0
SII
Prog_enable[1]
0
SDO
Prog_enable[2]
0
High-Voltage Serial Programming Algorithm
To program and verify the ATtiny13 in the High-voltage Serial Programming mode, the following
sequence is recommended (See instruction formats in Table 17-13 on page 110):
The following algorithm puts the device in High-voltage Serial Programming mode:
1. Set Prog_enable pins listed in Table 17-11 to “000”, RESET pin to “0” and Vcc to 0V.
2. Apply 4.5 - 5.5V between VCC and GND. Ensure that Vcc reaches at least 1.8V within
the next 20µs.
3. Wait 20 - 60µs, and apply 11.5 - 12.5V to RESET.
4. Keep the Prog_enable pins unchanged for at least 10µs after the High-voltage has
been applied to ensure the Prog_enable Signature has been latched.
5. Release the Prog_enable[2] pin to avoid drive contention on the Prog_enable[2]/SDO
pin.
6. Wait at least 300µs before giving any serial instructions on SDI/SII.
7. Exit Programming mode by power the device down or by bringing RESET pin to 0V.
If the rise time of the Vcc is unable to fulfill the requirements listed above, the following alternative algorithm can be used.
1. Set Prog_enable pins listed in Table 17-11 to “000”, RESET pin to “0” and Vcc to 0V.
2. Apply 4.5 - 5.5V between VCC and GND.
3. Monitor Vcc, and as soon as Vcc reaches 0.9 - 1.1V, apply 11.5 - 12.5V to RESET.
4. Keep the Prog_enable pins unchanged for at least 10µs after theHigh-voltage has been
applied to ensure the Prog_enable Signature has been latched.
5. Release the Prog_enable[2] pin to avoid drive contention on the Prog_enable[2]/SDO
pin.
109
2535I–AVR–05/08
6. Wait until Vcc actually reaches 4.5 - 5.5V before giving any serialinstructions on
SDI/SII.
7. Exit Programming mode by power the device down or by bringing RESET pin to 0V.
Table 17-12. High-voltage Reset Characteristics
RESET Pin High-voltage Threshold
Minimum High-voltage Period for
Latching Prog_enable
VCC
VHVRST
tHVRST
4.5V
12V
100 ns
5.5V
12
100 ns
Supply Voltage
17.7.2
High-Voltage Serial Programming Instruction set
The instruction set is described in Table 17-13.
Table 17-13. High-Voltage Serial Programming Instruction Set for ATtiny13
Instruction Format
Instruction
Chip Erase
Load “Write
Flash”
Command
Load Flash
Page Buffer
Instr.1/5
Instr.2/6
Instr.3
SDI
0_1000_0000_00
0_0000_0000_00
0_0000_0000_00
SII
0_0100_1100_00
0_0110_0100_00
0_0110_1100_00
SDO
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
SDI
0_0001_0000_00
SII
0_0100_1100_00
SDI
0_ bbbb_bbbb _00
0_eeee_eeee_00
0_dddd_dddd_00
0_0000_0000_00
SII
0_0000_1100_00
0_0010_1100_00
0_0011_1100_00
0_0111_1101_00
SDO
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
SDI
0_0000_0000_00
SII
0_0111_1100_00
110
Instr 5.
0_0000_000a_00
0_0000_0000_00
0_0000_0000_00
0_0001_1100_00
0_0110_0100_00
0_0110_1100_00
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
0_0000_0010_00
SII
0_0100_1100_00
Wait after Instr 3 until SDO goes
high. Repeat Instr. 2 - 3 for each
loaded Flash Page until the entire
Flash or all data is programmed.
Repeat Instr. 1 for a new 256 byte
page. See Note 1.
Enter Flash Read mode.
SDO
x_xxxx_xxxx_xx
SDI
0_bbbb_bbbb_00
0_0000_000a_00
0_0000_0000_00
0_0000_0000_00
SII
0_0000_1100_00
0_0001_1100_00
0_0110_1000_00
0_0110_1100_00
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
q_qqqq_qqqx_xx
0_0000_0000_00
0_0000_0000_00
SII
0_0111_1000_00
0_0111_1100_00
SDO
x_xxxx_xxxx_xx
p_pppp_pppx_xx
SDI
0_0001_0001_00
SII
0_0100_1100_00
SDO
Repeat after Instr. 1 - 5 until the
entire page buffer is filled or until all
data within the page is filled. See
Note 1.
x_xxxx_xxxx_xx
SDI
Read Flash Low SDO
and High Bytes SDI
Load “Write
EEPROM”
Command
Enter Flash Programming code.
x_xxxx_xxxx_xx
Load Flash High SDI
Address and
SII
Program Page
SDO
Operation Remarks
Wait after Instr.3 until SDO goes
high for the Chip Erase cycle to
finish.
SDO
SDO
Load “Read
Flash”
Command
Instr.4
x_xxxx_xxxx_xx
Repeat Instr. 1, 3 - 6 for each new
address. Repeat Instr. 2 for a new
256 byte page.
Instr 5 - 6.
Enter EEPROM Programming
mode.
ATtiny13
2535I–AVR–05/08
ATtiny13
Table 17-13. High-Voltage Serial Programming Instruction Set for ATtiny13 (Continued)
Instruction Format
Instruction
Load EEPROM
Page Buffer
Program
EEPROM Page
Write EEPROM
Byte
Load “Read
EEPROM”
Command
Read EEPROM
Byte
Write Fuse Low
Bits
Instr.1/5
Instr.2/6
Instr.3
Instr.4
SDI
0_00bb_bbbb_00
0_eeee_eeee_00
0_0000_0000_00
0_0000_0000_00
SII
0_0000_1100_00
0_0010_1100_00
0_0110_1101_00
0_0110_1100_00
SDO
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
SDI
0_0000_0000_00
0_0000_0000_00
SII
0_0110_0100_00
0_0110_1100_00
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
SDI
0_00bb_bbbb_00
0_eeee_eeee_00
0_0000_0000_00
0_0000_0000_00
SII
0_0000_1100_00
0_0010_1100_00
0_0110_1101_00
0_0110_0100_00
SDO
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
SDI
0_0000_0000_00
SII
0_0110_1100_00
x_xxxx_xxxx_xx
SDI
0_0000_0011_00
SII
0_0100_1100_00
Write Lock Bits
Read Fuse Low
Bits
SDI
0_bbbb_bbbb_00
0_aaaa_aaaa_00
0_0000_0000_00
0_0000_0000_00
SII
0_0000_1100_00
0_0001_1100_00
0_0110_1000_00
0_0110_1100_00
SDO
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
q_qqqq_qqq0_00
SDI
0_0100_0000_00
0_A987_6543_00
0_0000_0000_00
0_0000_0000_00
SII
0_0100_1100_00
0_0010_1100_00
0_0110_0100_00
0_0110_1100_00
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
0_0100_0000_00
0_000F_EDCB_00
0_0000_0000_00
0_0000_0000_00
0_0100_1100_00
0_0010_1100_00
0_0111_0100_00
0_0111_1100_00
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
SDI
0_0010_0000_00
0_0000_0021_00
0_0000_0000_00
0_0000_0000_00
SII
0_0100_1100_00
0_0010_1100_00
0_0110_0100_00
0_0110_1100_00
SDO
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
SDI
0_0000_0100_00
0_0000_0000_00
0_0000_0000_00
SII
0_0100_1100_00
0_0110_1000_00
0_0110_1100_00
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
A_9876_543x_xx
0_0000_0100_00
0_0000_0000_00
0_0000_0000_00
0_0100_1100_00
0_0111_1010_00
0_0111_1110_00
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxFE_DCBx_xx
SDI
0_0000_0100_00
0_0000_0000_00
0_0000_0000_00
SII
0_0100_1100_00
0_0111_1000_00
0_0111_1100_00
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_x21x_xx
SDO
SDI
Read Fuse High
SII
Bits
SDO
Read Lock Bits
Enter EEPROM Read mode.
x_xxxx_xxxx_xx
SDI
Write Fuse High
SII
Bits
SDO
SDO
Repeat Instr. 1 - 5 for each new
address. Wait after Instr. 5 until
SDO goes high. See Note 3.
Instr. 5
SDO
SDO
Repeat Instr. 1 - 4 until the entire
page buffer is filled or until all data
within the page is filled. See Note
2.
Wait after Instr. 2 until SDO goes
high. Repeat Instr. 1 - 2 for each
loaded EEPROM page until the
entire EEPROM or all data is
programmed.
SDO
SDO
Operation Remarks
Repeat Instr. 1, 3 - 4 for each new
address. Repeat Instr. 2 for a new
256 byte page.
Wait after Instr. 4 until SDO goes
high. Write A - 3 = “0” to program
the Fuse bit.
Wait after Instr. 4 until SDO goes
high. Write F - B = “0” to program
the Fuse bit.
Wait after Instr. 4 until SDO goes
high. Write 2 - 1 = “0” to program
the Lock Bit.
Reading A - 3 = “0” means the
Fuse bit is programmed.
Reading F - B = “0” means the fuse
bit is programmed.
Reading 2, 1 = “0” means the lock
bit is programmed.
111
2535I–AVR–05/08
Table 17-13. High-Voltage Serial Programming Instruction Set for ATtiny13 (Continued)
Instruction Format
Instruction
Read Signature
Bytes
Instr.1/5
Instr.2/6
Instr.3
Instr.4
SDI
0_0000_1000_00
0_0000_00bb_00
0_0000_0000_00
0_0000_0000_00
SII
0_0100_1100_00
0_0000_1100_00
0_0110_1000_00
0_0110_1100_00
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
q_qqqq_qqqx_xx
0_0000_1000_00
0_0000_000b_00
0_0000_0000_00
0_0000_0000_00
0_0100_1100_00
0_0000_1100_00
0_0111_1000_00
0_0111_1100_00
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
x_xxxx_xxxx_xx
p_pppp_pppx_xx
SDO
SDI
Read
SII
Calibration Byte
SDO
Load “No
Operation”
Command
SDI
0_0000_0000_00
SII
0_0100_1100_00
SDO
Operation Remarks
Repeats Instr 2 4 for each
signature byte address.
x_xxxx_xxxx_xx
Note:
a = address high bits, b = address low bits, d = data in high bits, e = data in low bits, p = data out high bits, q = data out low bits,
x = don’t care, 1 = Lock Bit1, 2 = Lock Bit2, 3 = CKSEL0 fuse, 4 = CKSEL1 fuse, 5 = SUT0 fuse, 6 = SUT1 fuse, 7 = CKDIV8,
fuse, 8 = WDTON fuse, 9 = EESAVE fuse, A = SPIEN fuse, B = RSTDISBL fuse, C = BODLEVEL0 fuse, D= BODLEVEL1 fuse,
E = MONEN fuse, F = SELFPRGEN fuse
Note:
The EEPROM is written page-wise. But only the bytes that are loaded into the page are actually written to the EEPROM. Pagewise EEPROM access is more efficient when multiple bytes are to be written to the same page. Note that auto-erase of
EEPROM is not available in High-voltage Serial Programming, only in SPI Programming.
17.8
Considerations for Efficient Programming
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.
• Skip writing the data value 0xFF that is the contents of the entire EEPROM (unless the
EESAVE fuse is programmed) and Flash after a Chip Erase.
• Address High byte needs only be loaded before programming or reading a new 256 word
window in Flash or 256 byte EEPROM. This consideration also applies to Signature bytes
reading.
17.8.1
Chip Erase
The Chip Erase will erase the Flash and EEPROM(1) memories plus 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 and/or EEPROM are re-programmed.
1. Load command “Chip Erase” (see Table 17-13 on page 110).
2. Wait after Instr. 3 until SDO goes high for the “Chip Erase” cycle to finish.
3. Load Command “No Operation”.
Note:
112
1. The EEPROM memory is preserved during Chip Erase if the EESAVE fuse is programmed.
ATtiny13
2535I–AVR–05/08
ATtiny13
17.8.2
Programming the Flash
The Flash is organized in pages, see Table 17-9 on page 107. 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:
1. Load Command “Write Flash” (see Table 17-13 on page 110).
2. Load Flash Page Buffer.
3. Load Flash High Address and Program Page. Wait after Instr. 3 until SDO goes high for
the “Page Programming” cycle to finish.
4. Repeat 2 through 3 until the entire Flash is programmed or until all data has been
programmed.
5. End Page Programming by Loading Command “No Operation”.
When writing or reading serial data to the ATtiny13, data is clocked on the rising edge of the
serial clock, see Figure 17-4 on page 114, Figure 18-6 on page 122 and Table 18-9 on page 122
for details.
Figure 17-3. Addressing the Flash which is Organized in Pages
PCMSB
PROGRAM
COUNTER
PAGEMSB
PCPAGE
PAGE ADDRESS
WITHIN THE FLASH
PROGRAM MEMORY
PAGE
PCWORD
WORD ADDRESS
WITHIN A PAGE
PAGE
INSTRUCTION WORD
PCWORD[PAGEMSB:0]:
00
01
02
PAGEEND
113
2535I–AVR–05/08
Figure 17-4. High-voltage Serial Programming Waveforms
SDI
PB0
MSB
LSB
SII
PB1
MSB
LSB
SDO
PB2
SCI
PB3
17.8.3
MSB
0
LSB
1
2
3
4
5
6
7
8
9
10
Programming the EEPROM
The EEPROM is organized in pages, see Table 18-8 on page 121. When programming the
EEPROM, the data is latched into a page buffer. This allows one page of data to be programmed simultaneously. The programming algorithm for the EEPROM Data memory is as
follows (refer to Table 17-13 on page 110):
1. Load Command “Write EEPROM”.
2. Load EEPROM Page Buffer.
3. Program EEPROM Page. Wait after Instr. 2 until SDO goes high for the “Page Programming” cycle to finish.
4. Repeat 2 through 3 until the entire EEPROM is programmed or until all data has been
programmed.
5. End Page Programming by Loading Command “No Operation”.
17.8.4
Reading the Flash
The algorithm for reading the Flash memory is as follows (refer to Table 17-13 on page 110):
1. Load Command "Read Flash".
2. Read Flash Low and High Bytes. The contents at the selected address are available at
serial output SDO.
17.8.5
Reading the EEPROM
The algorithm for reading the EEPROM memory is as follows (refer to Table 17-13 on page
110):
1. Load Command “Read EEPROM”.
2. Read EEPROM Byte. The contents at the selected address are available at serial output SDO.
17.8.6
114
Programming and Reading the Fuse and Lock Bits
The algorithms for programming and reading the fuse low/high bits and lock bits are shown in
Table 17-13 on page 110.
ATtiny13
2535I–AVR–05/08
ATtiny13
17.8.7
Reading the Signature Bytes and Calibration Byte
The algorithms for reading the Signature bytes and Calibration byte are shown in Table 17-13 on
page 110.
17.8.8
Power-off sequence
Set SCI to “0”. Set RESET to “1”. Turn VCC power off.
18. Electrical Characteristics
18.1
Absolute Maximum Ratings*
Operating Temperature.................................. -55°C to +125°C
*NOTICE:
Storage Temperature ..................................... -65°C to +150°C
Voltage on any Pin except RESET
with respect to Ground ................................-0.5V to VCC+0.5V
Voltage on RESET with respect to Ground......-0.5V to +13.0V
Stresses beyond those listed under “Absolute
Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and
functional operation of the device at these or
other conditions beyond those indicated in the
operational sections of this specification is not
implied. Exposure to absolute maximum rating
conditions for extended periods may affect
device reliability.
Maximum Operating Voltage ............................................ 6.0V
DC Current per I/O Pin ............................................... 40.0 mA
DC Current VCC and GND Pins................................ 200.0 mA
18.2
DC Characteristics
Table 18-1.
Symbol
DC Characteristics, TA = -40°C to 85°C
Parameter
Input Low Voltage,
Any Pin as I/O
VIL
Input Low Voltage,
RESET Pin as Reset (2)
Input High Voltage,
Any Pin as I/O
VIH
Input High Voltage,
RESET Pin as Reset (2)
VCC = 1.8V - 2.4V
Min
-0.5
Typ
Max
Units
0.2VCC
(1)
V
(1)
V
VCC = 2.4V - 5.5V
-0.5
0.3VCC
VCC = 1.8V - 5.5
-0.5
0.2VCC (1)
V
VCC = 1.8V - 2.4V
0.7VCC (3)
VCC + 0.5
V
VCC = 2.4V - 5.5V
0.6VCC (3)
VCC + 0.5
V
VCC = 1.8V - 5.5V
0.9VCC (3)
VCC + 0.5
V
Output Low Voltage,
Pins PB0 and PB1 (4)
IOL = 20 mA, VCC = 5V
0.7
V
IOL = 10 mA, VCC = 3V
0.5
V
Output Low Voltage,
Pins PB2, PB3 and PB4 (4)
IOL = 10 mA, VCC = 5V
0.7
V
IOL = 5 mA, VCC = 3V
0.5
V
Output High Voltage,
Pins PB0 and PB1 (5)
IOH = -20 mA, VCC = 5V
4.2
V
IOH = -10 mA, VCC = 3V
2.5
V
Output High Voltage,
Pins PB2, PB3 and PB4 (5)
IOH = -10 mA, VCC = 5V
4.2
V
IOH = -5 mA, VCC = 3V
2.5
V
VCC = 5.5V, pin low
-1
VOL
VOH
ILIL
Condition
Input Leakage
Current I/O Pin
1
µA
115
2535I–AVR–05/08
Table 18-1.
Symbol
ILIH
RPU
DC Characteristics, TA = -40°C to 85°C (Continued)
Parameter
Condition
Input Leakage
Current I/O Pin
VCC = 5.5V, pin high
Pull-Up Resistor, I/O Pin
Pull-Up Resistor, Reset Pin
Supply Current,
Active Mode
ICC
Supply Current,
Idle Mode
Supply Current,
Power-Down Mode
Notes:
Min
Typ
Max
Units
-1
1
µA
VCC = 5.5V, input low
20
50
kΩ
VCC = 5.5V, input low
30
80
kΩ
f = 1MHz, VCC = 2V
0.3
0.35
mA
f = 4MHz, VCC = 3V
1.6
1.8
mA
f = 8MHz, VCC = 5V
5
6
mA
f = 1MHz, VCC = 2V
0.08
0.2
mA
f = 4MHz, VCC = 3V
0.41
1
mA
f = 8MHz, VCC = 5V
1.6
3
mA
WDT enabled, VCC = 3V
5
10
µA
WDT disabled, VCC = 3V
0.5
2
µA
1. “Max” means the highest value where the pin is guaranteed to be read as low.
2. Not tested in production.
3. “Min” means the lowest value where the pin is guaranteed to be read as high.
4. Although each I/O port can under non-transient, steady state conditions sink more than the test conditions, the sum of all IOL
(for all ports) should not exceed 60 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.
5. Although each I/O port can under non-transient, steady state conditions source more than the test conditions, the sum of all
IOH (for all ports) should not exceed 60 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.
116
ATtiny13
2535I–AVR–05/08
ATtiny13
18.3
Speed Grades
The maximum operating frequency of the device depends on VCC. As shown in Figure 18-1 and
Figure 18-2, the maximum frequency vs. VCC relationship is linear between 1.8V < VCC < 2.7V
and between 2.7V < VCC < 4.5V.
Figure 18-1. Maximum Frequency vs. VCC for ATtiny13V
10 MHz
Safe Operating Area
4 MHz
1.8V
2.7V
5.5V
Figure 18-2. Maximum Frequency vs. VCC for ATtiny13
20 MHz
10 MHz
Safe Operating Area
2.7V
4.5V
5.5V
117
2535I–AVR–05/08
18.4
Clock Characteristics
18.4.1
Calibrated Internal RC Oscillator Accuracy
It is possible to manually calibrate the internal oscillator to be more accurate than default factory
calibration. Note that the oscillator frequency depends on temperature and voltage. Voltage and
temperature characteristics can be found in Figure 19-50 on page 148, Figure 19-51 on page
148, Figure 19-52 on page 149, Figure 19-53 on page 149, Figure 19-54 on page 150, and Figure 19-55 on page 150.
Table 18-2.
Calibration Accuracy of Internal RC Oscillator
Calibration
Method
Target Frequency
VCC
Temperature
Accuracy at given Voltage
& Temperature(1)
4.8 / 9.6 MHz
3V
25°C
±10%
Fixed frequency within:
4 – 5 MHz / 8 – 10 MHz
Fixed voltage within:
1.8V – 5.5V(2)
2.7V – 5.5V(3)
Fixed temperature
within:
-40°C – 85°C
±2%
Factory
Calibration
User
Calibration
Notes:
1. Accuracy of oscillator frequency at calibration point (fixed temperature and fixed voltage).
2. Voltage range for ATtiny13V.
3. Voltage range for ATtiny13.
18.4.2
External Clock Drive
Figure 18-3. External Clock Drive Waveform
V IH1
V IL1
Table 18-3.
External Clock Drive
VCC = 1.8 - 5.5V
VCC = 2.7 - 5.5V
VCC = 4.5 - 5.5V
Symbol
Parameter
1/tCLCL
Clock Frequency
tCLCL
Clock Period
250
100
50
ns
tCHCX
High Time
100
40
20
ns
tCLCX
Low Time
100
40
20
ns
tCLCH
Rise Time
2.0
1.6
0.5
µs
tCHCL
Fall Time
2.0
1.6
0.5
µs
ΔtCLCL
Change in period from one clock cycle to the next
2
2
2
%
118
Min.
Max.
Min.
Max.
Min.
Max.
Units
0
4
0
10
0
20
MHz
ATtiny13
2535I–AVR–05/08
ATtiny13
18.5
System and Reset Characteristics
Table 18-4.
Reset, Brown-out and Internal Voltage Reference Characteristics
Symbol
Parameter
Condition
Min
Typ
Max
Units
Power-on Reset Threshold Voltage (rising)
TA = -40 - 85°C
1.2
V
VPOT
Power-on Reset Threshold Voltage
(falling)(1)
TA = -40 - 85°C
1.1
V
VRST
RESET Pin Threshold Voltage
VCC = 1.8V - 5.5V
tRST
Minimum pulse width on RESET Pin
VCC = 1.8V - 5.5V
VHYST
Brown-out Detector Hysteresis
tBOD
Min Pulse Width on Brown-out Reset
VBG
Bandgap reference voltage
tBG
IBG
µs
mV
2
µs
V
Bandgap reference start-up time
40
70
µs
Bandgap reference current consumption
15
µs
1. The Power-on Reset will not work unless the supply voltage has been below VPOT (falling)
Brown-Out Detection
VBOT vs. BODLEVEL Fuse Coding
Min(1)
11
Note:
Typ(1)
Max(1)
Units
BOD Disabled
10
1.8
01
2.7
00
4.3
V
1. VBOT may be below nominal minimum operating voltage for some devices. For devices where
this is the case, the device is tested down to VCC = VBOT during the production test. This guarantees that a Brown-out Reset will occur before VCC drops to a voltage where correct
operation of the microcontroller is no longer guaranteed.
Analog Comparator Characteristics
Table 18-6.
Analog Comparator Characteristics, TA = -40°C - 85°C
Symbol
Parameter
Condition
VAIO
Input Offset Voltage
VCC = 5V, VIN = VCC / 2
ILAC
Input Leakage Current
VCC = 5V, VIN = VCC / 2
Analog Propagation Delay
(from saturation to slight overdrive)
VCC = 2.7V
750
VCC = 4.0V
500
Analog Propagation Delay
(large step change)
VCC = 2.7V
100
VCC = 4.0V
75
Digital Propagation Delay
VCC = 1.8V - 5.5
1
tAPD
Note:
2.5
50
1.0
BODLEVEL [1:0] Fuses
tDPD
V
1.2
Table 18-5.
18.6
0.9 VCC
1.1
Note:
18.5.1
0.2 VCC
Min
Typ
Max
Units
< 10
40
mV
50
nA
-50
ns
2
CLK
All parameters are based on simulation results and they are not tested in production
119
2535I–AVR–05/08
18.7
ADC Characteristics
Table 18-7.
Symbol
ADC Characteristics, Single Ended Channels. TA = -40°C - 85°C
Parameter
Condition
Min
Typ
Resolution
Absolute accuracy
(Including INL, DNL, and
Quantization, Gain and Offset
Errors)
10
Bits
VREF = 4V, VCC = 4V,
ADC clock = 200 kHz
2
LSB
VREF = 4V, VCC = 4V
ADC clock = 1 MHz
3
LSB
VREF = 4V, VCC = 4V
ADC clock = 200 kHz
Noise Reduction Mode
1.5
LSB
VREF = 4V, VCC = 4V,
ADC clock = 1 MHz
Noise Reduction Mode
2.5
LSB
VREF = 4V, VCC = 4V
ADC clock = 200 kHz
1
LSB
Differential Non-linearity
(DNL)
VREF = 4V, VCC = 4V
ADC clock = 200 kHz
0.5
LSB
Gain Error
VREF = 4V, VCC = 4V
ADC clock = 200 kHz
2.5
LSB
Offset Error
VREF = 4V, VCC = 4V
ADC clock = 200 kHz
1.5
LSB
Conversion Time
Free Running Conversion
Input Voltage
13
260
µs
50
1000
kHz
GND
VREF
V
Input Bandwidth
VINT
Internal Voltage Reference
RAIN
Analog Input Resistance
120
Units
Integral Non-Linearity (INL)
(Accuracy after Offset and
Gain Calibration)
Clock Frequency
VIN
Max
38.5
1.0
1.1
100
kHz
1.2
V
MΩ
ATtiny13
2535I–AVR–05/08
ATtiny13
18.8
Serial Programming Characteristics
Figure 18-4. Serial Programming Timing
MOSI
SCK
tSLSH
tSHOX
tOVSH
tSHSL
MISO
Figure 18-5. Serial Programming Waveform
SERIAL DATA INPUT
(MOSI)
MSB
LSB
SERIAL DATA OUTPUT
(MISO)
MSB
LSB
SERIAL CLOCK INPUT
(SCK)
SAMPLE
Table 18-8.
Serial Programming Characteristics, TA = -40°C to 85°C, VCC = 1.8 - 5.5V (Unless
Otherwise Noted)
Symbol
Parameter
1/tCLCL
Oscillator Frequency (ATtiny13V, VCC = 1.8 - 5.5V)
Oscillator Period (ATtiny13V, VCC = 1.8 - 5.5V)
tCLCL
1/tCLCL
Oscillator Period (ATtiny13, VCC = 2.7 - 5.5V)
tCLCL
1/tCLCL
tCLCL
tSHSL
Oscillator Frequency (ATtiny13, VCC = 2.7 - 5.5V)
0
50
tOVSH
MOSI Setup to SCK High
tSHOX
MOSI Hold after SCK High
Units
1
MHz
ns
9.6
104
Oscillator Period (ATtiny13, VCC = 4.5V - 5.5V)
SCK Pulse Width Low
Max
1000
0
SCK Pulse Width High
Typ
0
Oscillator Frequency (ATtiny13, VCC = 4.5V - 5.5V)
tSLSH
Note:
Min
MHz
ns
20
MHz
ns
(1)
ns
(1)
2 tCLCL
ns
tCLCL
ns
2 tCLCL
ns
2 tCLCL
1. 2 tCLCL for fck < 12 MHz, 3 tCLCL for fck >= 12 MHz
121
2535I–AVR–05/08
18.9
High-voltage Serial Programming Characteristics
Figure 18-6. High-voltage Serial Programming Timing
SDI (PB0), SII (PB1)
tIVSH
SCI (PB3)
tSLSH
tSHIX
tSHSL
SDO (PB2)
tSHOV
Table 18-9.
Symbol
122
High-voltage Serial Programming Characteristics
TA = 25°C, VCC = 5.0V ± 10% (Unless otherwise noted)
Parameter
Min
Typ
Max
Units
tSHSL
SCI (PB3) Pulse Width High
110
ns
tSLSH
SCI (PB3) Pulse Width Low
110
ns
tIVSH
SDI (PB0), SII (PB1) Valid to SCI (PB3) High
50
ns
tSHIX
SDI (PB0), SII (PB1) Hold after SCI (PB3) High
50
ns
tSHOV
SCI (PB3) High to SDO (PB2) Valid
16
ns
tWLWH_PFB
Wait after Instr. 3 for Write Fuse Bits
2.5
ms
ATtiny13
2535I–AVR–05/08
ATtiny13
19. Typical Characteristics
The data contained in this section is largely based on simulations and characterization of similar
devices in the same process and design methods. Thus, the data should be treated as indications of how the part will behave.
The following charts show typical behavior. These figures are not tested during manufacturing.
During characterisation devices are operated at frequencies higher than test limits but they are
not guaranteed to function properly at frequencies higher than the ordering code indicates.
All current consumption measurements are performed with all I/O pins configured as inputs and
with internal pull-ups enabled. 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.
A sine wave generator with rail-to-rail output is used as clock source but current consumption in
Power-Down mode is independent of clock selection. 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.
The current drawn from pins with a capacitive load may be estimated (for one pin) as follows:
I CP ≈ V CC × C L × f SW
where VCC = operating voltage, CL = load capacitance and fSW = average switching frequency of
I/O pin.
19.1
Active Supply Current
Figure 19-1. Active Supply Current vs. Frequency (0.1 - 1.0 MHz)
ACTIVE SUPPLY CURRENT vs. LOW FREQUENCY
0.1 - 1.0 MHz
1.2
5.5 V
1
5.0 V
ICC (mA)
0.8
4.5 V
4.0 V
0.6
3.3 V
2.7 V
0.4
1.8 V
0.2
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Frequency (MHz)
123
2535I–AVR–05/08
Figure 19-2. Active Supply Current vs. Frequency (1 - 20 MHz)
ACTIVE SUPPLY CURRENT vs. FREQUENCY
1 - 20MHz
14
5.5 V
12
5.0 V
ICC (mA)
10
4.5 V
8
6
4.0 V
3.3 V
2.7 V
4
2
1.8 V
0
0
2
4
6
8
10
12
14
16
18
20
Frequency (MHz)
Figure 19-3. Active Supply Current vs. VCC (Internal RC Oscillator, 9.6 MHz)
ACTIVE SUPPLY CURRENT vs. VCC
INTERNAL RC OSCILLATOR, 9.6 MHz
8
85 °C
-40 °C
7
6
25 °C
ICC (mA)
5
4
3
2
1
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
124
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-4. Active Supply Current vs. VCC (Internal RC Oscillator, 4.8 MHz)
ACTIVE SUPPLY CURRENT vs. VCC
INTERNAL RC OSCILLATOR, 4.8 MHz
4.5
25 °C
-40 °C
85 °C
4
3.5
ICC (mA)
3
2.5
2
1.5
1
0.5
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
Figure 19-5. Active Supply Current vs. VCC (Internal WDT Oscillator, 128 kHz)
ACTIVE SUPPLY CURRENT vs. V CC
INTERNAL WD OSCILLATOR, 128 KHz
0.14
-40 °C
25 °C
85 °C
0.12
ICC (mA)
0.1
0.08
0.06
0.04
0.02
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
125
2535I–AVR–05/08
Figure 19-6. Active Supply Current vs. VCC (32 kHz External Clock)
ACTIVE SUPPLY CURRENT vs. V CC
32 kHz EXTERNAL CLOCK
0.04
25 °C
0.035
85 °C
0.03
ICC (mA)
0.025
0.02
0.015
0.01
0.005
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
19.2
Idle Supply Current
Figure 19-7. Idle Supply Current vs. Frequency (0.1 - 1.0 MHz)
IDLE SUPPLY CURRENT vs. LOW FREQUENCY
(0.1 - 1.0 MHz)
ICC (mA)
0.9
0.8
5.5 V
0.7
5.0 V
0.6
4.5 V
0.5
4.0 V
0.4
3.3 V
0.3
2.7 V
0.2
1.8 V
0.1
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Frequency (MHz)
126
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-8. Idle Supply Current vs. Frequency (1 - 20 MHz)
IDLE SUPPLY CURRENT vs. FREQUENCY
1 - 20MHz
5
ICC (mA)
4.5
4
5.5 V
3.5
5.0 V
3
4.5 V
2.5
2
1.5
4.0 V
1
3.3 V
2.7 V
0.5
1.8 V
0
0
2
4
6
8
10
12
14
16
18
20
Frequency (MHz)
Figure 19-9. Idle Supply Current vs. VCC (Internal RC Oscillator, 9.6 MHz)
IDLE SUPPLY CURRENT vs. VCC
INTERNAL RC OSCILLATOR, 9.6 MHz
2.5
85 °C
25 °C
-40 °C
ICC (mA)
2
1.5
1
0.5
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
127
2535I–AVR–05/08
Figure 19-10. Idle Supply Current vs. VCC (Internal RC Oscillator, 4.8 MHz)
IDLE SUPPLY CURRENT vs. VCC
INTERNAL RC OSCILLATOR, 4.8 MHz
1.2
85 °C
25 °C
-40 °C
1
ICC (mA)
0.8
0.6
0.4
0.2
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
Figure 19-11. Idle Supply Current vs. VCC (Internal RC Oscillator, 128 kHz)
IDLE SUPPLY CURRENT vs. VCC
INTERNAL WD OSCILLATOR, 128 KHz
0.035
-40 °C
25 °C
85 °C
0.03
ICC (mA)
0.025
0.02
0.015
0.01
0.005
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
128
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-12. Idle Supply Current vs. VCC (32 kHz External Clock)
IDLE SUPPLY CURRENT vs. VCC
32kHz EXTERNAL CLOCK
10
9
85 °C
8
25 °C
-40 °C
ICC (uA)
7
6
5
4
3
2
1
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
19.3
Power-Down Supply Current
Figure 19-13. Power-Down Supply Current vs. VCC (Watchdog Timer Disabled)
POWER-DOWN SUPPLY CURRENT vs. VCC
WATCHDOG TIMER DISABLED
1.8
1.6
85 ˚C
1.4
ICC (uA)
1.2
1
0.8
-40 ˚C
25 ˚C
0.6
0.4
0.2
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
129
2535I–AVR–05/08
Figure 19-14. Power-Down Supply Current vs. VCC (Watchdog Timer Enabled)
POWER-DOWN SUPPLY CURRENT vs. VCC
WATCHDOG TIMER ENABLED
10
-40 ˚C
85 ˚C
25 ˚C
9
8
ICC (uA)
7
6
5
4
3
2
1
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
19.4
Pin Pull-up
Figure 19-15. I/O Pin Pull-up Resistor Current vs. Input Voltage (VCC = 5V)
I/O PIN PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE
VCC = 5V
160
140
25 ˚C
85 ˚C
120
-40 ˚C
IOP (uA)
100
80
60
40
20
0
0
1
2
3
4
5
6
VOP (V)
130
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-16. I/O Pin Pull-up Resistor Current vs. Input Voltage (VCC = 2.7V)
I/O PIN PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE
VCC = 2.7
80
25 ˚C
85 ºC
70
60
-40 ˚C
IOP (uA)
50
40
30
20
10
0
0
0.5
1
1.5
2
2.5
3
VOP (V)
Figure 19-17. Reset Pull-up Resistor Current vs. Reset Pin Voltage (VCC = 5V)
RESET PULL-UP RESISTOR CURRENT vs. RESET PIN VOLTAGE
VCC = 5V
120
-40 ˚C
25 ˚C
100
85 ˚C
IRESET (uA)
80
60
40
20
0
0
1
2
3
4
5
VRESET (V)
131
2535I–AVR–05/08
Figure 19-18. Reset Pull-up Resistor Current vs. Reset Pin Voltage (VCC = 2.7V)
RESET PULL-UP RESISTOR CURRENT vs. RESET PIN VOLTAGE
VCC = 2.7V
60
25 ˚C
-40 ˚C
50
85 ˚C
IRESET (uA)
40
30
20
10
0
0
0.5
1
1.5
2
2.5
3
VRESET (V)
19.5
Pin Driver Strength
Figure 19-19. I/O Pin Source Current vs. Output Voltage (Low Power Ports, VCC = 5V)
I/O PIN SOURCE CURRENT vs. OUTPUT VOLTAGE
LOW POWER PORTS, VCC = 5V
70
-40 ˚C
60
25 ˚C
50
IOH (mA)
85 ˚C
40
30
20
10
0
0
1
2
3
4
5
6
VOH (V)
132
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-20. I/O Pin Source Current vs. Output Voltage (Low Power Ports, VCC = 2.7V)
I/O PIN SOURCE CURRENT vs. OUTPUT VOLTAGE
LOW POWER PORTS, VCC = 2.7V
25
-40 °C
IOH (mA)
20
25 °C
85 °C
15
10
5
0
0
0.5
1
1.5
2
2.5
3
VOH (V)
Figure 19-21. I/O Pin Source Current vs. Output Voltage (Low Power Ports, VCC = 1.8V)
I/O PIN SOURCE CURRENT vs. OUTPUT VOLTAGE
LOW POWER PORTS, VCC = 1.8V
7
-40 ˚C
25 ˚C
6
85 ˚C
IOH (mA)
5
4
3
2
1
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
VOH (V)
133
2535I–AVR–05/08
Figure 19-22. I/O Pin Sink Current vs. Output Voltage (Low Power Ports, VCC = 5V)
I/O PIN SINK CURRENT vs. OUTPUT VOLTAGE
LOW POWER PORTS, VCC = 5V
50
45
-40 ˚C
40
25 ˚C
IOL (mA)
35
85 ˚C
30
25
20
15
10
5
0
0
0.5
1
1.5
2
2.5
VOL (V)
Figure 19-23. I/O Pin Sink Current vs. Output Voltage (Low Power Ports, VCC = 2.7V)
I/O PIN SINK CURRENT vs. OUTPUT VOLTAGE
Low Power Ports, VCC = 2.7V
20
18
-40 ˚C
16
25 ˚C
IOL (mA)
14
85 ˚C
12
10
8
6
4
2
0
0
0.5
1
1.5
2
2.5
VOL (V)
134
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-24. I/O Pin Sink Current vs. Output Voltage (Low Power Ports, VCC = 1.8V)
I/O PIN SINK CURRENT vs. OUTPUT VOLTAGE
LOW POWER PORTS, 1.8V
7
6
-40 ˚C
IOL (mA)
5
25 ˚C
85 ˚C
4
3
2
1
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
VOL (V)
Figure 19-25. I/O Pin Source Current vs. Output Voltage (VCC = 5V)
I/O PIN SOURCE CURRENT vs. OUTPUT VOLTAGE
VCC = 5V
90
80
-40 ˚C
70
25 ˚C
85 ˚C
IOH (mA)
60
50
40
30
20
10
0
2
3
4
5
6
VOH (V)
135
2535I–AVR–05/08
Figure 19-26. I/O Pin Source Current vs. Output Voltage (VCC = 2.7V)
I/O PIN SOURCE CURRENT vs. OUTPUT VOLTAGE
VCC = 2.7V
35
30
-40 ˚C
25 ˚C
25
IOH (mA)
85 ˚C
20
15
10
5
0
0
0.5
1
1.5
2
2.5
3
VOH (V)
Figure 19-27. I/O Pin Source Current vs. Output Voltage (VCC = 1.8V)
I/O PIN SOURCE CURRENT vs. OUTPUT VOLTAGE
VCC = 1.8V
10
-40 ˚C
9
25 ˚C
8
85 ˚C
IOH (mA)
7
6
5
4
3
2
1
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
VOH (V)
136
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-28. I/O Pin Sink Current vs. Output Voltage (VCC = 5V)
I/O PIN SINK CURRENT vs. OUTPUT VOLTAGE
VCC = 5V
100
90
-40 ˚C
80
25 ˚C
IOL (mA)
70
85 ˚C
60
50
40
30
20
10
0
0
0.5
1
1.5
2
2.5
VOL (V)
Figure 19-29. I/O Pin Sink Current vs. Output Voltage (VCC = 2.7V)
I/O PIN SINK CURRENT vs. OUTPUT VOLTAGE
VCC = 2.7V
40
35
-40 ˚C
30
25 ˚C
IOL (mA)
25
85 ˚C
20
15
10
5
0
0
0.5
1
1.5
2
2.5
VOL (V)
137
2535I–AVR–05/08
Figure 19-30. I/O Pin Sink Current vs. Output Voltage (VCC = 1.8V)
I/O PIN SINK CURRENT vs. OUTPUT VOLTAGE
VCC = 1.8V
14
12
-40 ˚C
IOL (mA)
10
25 ˚C
85 ˚C
8
6
4
2
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
VOL (V)
Figure 19-31. Reset Pin as I/O - Source Current vs. Output Voltage (VCC = 5V)
RESET PIN AS I/O - SOURCE CURRENT vs. OUTPUT VOLTAGE
VCC = 5V
1.6
1.4
-40 ˚C
1.2
25 ˚C
IOH (mA)
1
85 ˚C
0.8
0.6
0.4
0.2
0
2
3
4
5
VOH (V)
138
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-32. Reset Pin as I/O - Source Current vs. Output Voltage (VCC = 2.7V)
RESET PIN AS I/O - SOURCE CURRENT vs. OUTPUT VOLTAGE
VCC = 2.7V
2.5
-40 ˚C
2
IOH (mA)
25 ˚C
85 ˚C
1.5
1
0.5
0
0
0.5
1
1.5
2
2.5
3
VOH (V)
Figure 19-33. Reset Pin as I/O - Source Current vs. Output Voltage (VCC = 1.8V)
RESET PIN AS I/O - SOURCE CURRENT vs. OUTPUT VOLTAGE
VCC = 1.8V
2.5
-40 °C
2
IOH (mA)
25 °C
1.5
1
85 °C
0.5
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
VOH (V)
139
2535I–AVR–05/08
Figure 19-34. Reset Pin as I/O - Sink Current vs. Output Voltage (VCC = 5V)
RESET PIN AS I/O - SINK CURRENT vs. OUTPUT VOLTAGE
VCC = 5V
14
-40 ˚C
12
25 ˚C
IOL (mA)
10
85 ˚C
8
6
4
2
0
0
0.5
1
1.5
2
2.5
VOL (V)
Figure 19-35. Reset Pin as I/O - Sink Current vs. Output Voltage (VCC = 2.7V)
RESET PIN AS I/O - SINK CURRENT vs. OUTPUT VOLTAGE
VCC = 2.7V
4.5
-40 ˚C
4
3.5
25 ˚C
IOL (mA)
3
85 ˚C
2.5
2
1.5
1
0.5
0
0
0.5
1
1.5
2
2.5
VOL (V)
140
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-36. Reset Pin as I/O - Sink Current vs. Output Voltage (VCC = 1.8V)
RESET PIN AS I/O - SINK CURRENT vs. OUTPUT VOLTAGE
VCC = 1.8V
1.6
1.4
-40 ˚C
1.2
25 ˚C
IOL (mA)
1
85 ˚C
0.8
0.6
0.4
0.2
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
VOL (V)
19.6
Pin Thresholds and Hysteresis
Figure 19-37. I/O Pin Input Threshold Voltage vs. VCC (VIH, I/O Pin Read as '1')
I/O PIN INPUT THRESHOLD VOLTAGE vs. VCC
VIH, IO PIN READ AS '1'
3
85 ˚C
25 ˚C
2.5
-40 ˚C
Threshold (V)
2
1.5
1
0.5
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
141
2535I–AVR–05/08
Figure 19-38. I/O Pin Input Threshold Voltage vs. VCC (VIL, I/O Pin Read as '0')
I/O PIN INPUT THRESHOLD VOLTAGE vs. VCC
VIL, IO PIN READ AS '0'
3
85 ˚C
25 ˚C
-40 ˚C
2.5
Threshold (V)
2
1.5
1
0.5
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
5
5.5
VCC (V)
Figure 19-39. I/O Pin Input Hysteresis vs. VCC
I/O PIN INPUT HYSTERESIS vs. VCC
0.45
0.4
-40 ºC
Input Hysteresis (V)
0.35
0.3
25 ºC
0.25
0.2
85 ºC
0.15
0.1
0.05
0
1.5
2
2.5
3
3.5
4
4.5
VCC (V)
142
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-40. Reset Pin as I/O - Input Threshold Voltage vs. VCC (VIH, Reset Pin Read as '1')
RESET PIN AS I/O - THRESHOLD VOLTAGE vs. VCC
VIH, IO PIN READ AS '1'
3
2.5
Threshold (V)
2
-40 ˚C
1.5
25 ˚C
1
85 ˚C
0.5
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
Figure 19-41. Reset Pin as I/O - Input Threshold Voltage vs. VCC (VIL, Reset Pin Read as '0')
RESET PIN AS I/O - THRESHOLD VOLTAGE vs. VCC
VIL, IO PIN READ AS '0'
2.5
Threshold (V)
2
1.5
85 ˚C
1
25 ˚C
0.5
-40 ˚C
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
143
2535I–AVR–05/08
Figure 19-42. Reset Pin as I/O - Pin Hysteresis vs. VCC
RESET PIN AS IO - PIN HYSTERESIS vs. VCC
0.7
0.6
-40 ºC
Input Hysteresis (V)
0.5
25 ºC
0.4
85 ºC
0.3
0.2
0.1
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
Figure 19-43. Reset Input Threshold Voltage vs. VCC (VIH, Reset Pin Read as '1')
RESET INPUT THRESHOLD VOLTAGE vs. VCC
VIH, IO PIN READ AS '1'
2.5
Threshold (V)
2
1.5
-40 ˚C
1
85 ˚C
25 ˚C
0.5
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
144
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-44. Reset Input Threshold Voltage vs. VCC (VIL, Reset Pin Read as '0')
RESET INPUT THRESHOLD VOLTAGE vs. VCC
VIL, IO PIN READ AS '0'
2.5
Threshold (V)
2
1.5
1
0.5
85 ˚C
25 ˚C
-40 ˚C
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
Figure 19-45. Reset Input Pin Hysteresis vs. VCC
RESET INPUT THRESHOLD VOLTAGE vs. VCC
VIL, IO PIN READ AS '0'
0.5
-40 ºC
Threshold (V)
0.4
0.3
85 ºC
0.2
25 ºC
0.1
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
145
2535I–AVR–05/08
19.7
BOD Thresholds and Analog Comparator Offset
Figure 19-46. BOD Thresholds vs. Temperature (BODLEVEL is 4.3V)
BOD THRESHOLDS vs. TEMPERATURE
BODLEVEL IS 4.3V
4.5
Rising VCC
Threshold (V)
4.4
4.3
Falling VCC
4.2
-60
-40
-20
0
20
40
60
80
100
80
100
Temperature (C)
Figure 19-47. BOD Thresholds vs. Temperature (BODLEVEL is 2.7V)
BOD THRESHOLDS vs. TEMPERATURE
BODLEVEL IS 2.7V
2.9
Rising V CC
Threshold (V)
2.8
2.7
Falling V CC
2.6
-60
-40
-20
0
20
40
60
Temperature (C)
146
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-48. BOD Thresholds vs. Temperature (BODLEVEL is 1.8V)
BOD THRESHOLDS vs. TEMPERATURE
BODLEVEL IS 1.8V
1.9
Rising V CC
Threshold (V)
1.85
1.8
Falling V CC
1.75
-60
-40
-20
0
20
40
60
80
100
Temperature (C)
Figure 19-49. Bandgap Voltage vs. VCC
BANDGAP VOLTAGE vs. VCC
1.06
Bandgap Voltage (V)
1.04
1.02
85ºC
25ºC
1
0.98
-40ºC
0.96
0.94
0.92
1.5
2.5
3.5
4.5
5.5
VCC (V)
147
2535I–AVR–05/08
19.8
Internal Oscillator Speed
Figure 19-50. Calibrated 9.6 MHz RC Oscillator Frequency vs. Temperature
CALIBRATED 9.6 MHz RC OSCILLATOR FREQUENCY vs. TEMPERATURE
10.3
10.1
9.9
FRC (MHz)
9.7
9.5
5.5 V
9.3
4.5 V
9.1
2.7 V
8.9
1.8 V
8.7
8.5
-60
-40
-20
0
20
40
60
80
100
Temperature (C)
Figure 19-51. Calibrated 9.6 MHz RC Oscillator Frequency vs. VCC
CALIBRATED 9.6 MHz RC OSCILLATOR FREQUENCY vs. VCC
11
10.5
85 ˚C
FRC (MHz)
10
25 ˚C
9.5
-40 ˚C
9
8.5
8
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
148
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-52. Calibrated 9.6 MHz RC Oscillator Frequency vs. Osccal Value
CALIBRATED 9.6MHz RC OSCILLATOR FREQUENCY vs. OSCCAL VALUE
18
25 ˚C
16
FRC (MHz)
14
12
10
8
6
4
2
0
8
16
24
32
40
48
56
64
72
80
88
96
104
112
120
OSCCAL VALUE
Figure 19-53. Calibrated 4.8 MHz RC Oscillator Frequency vs. Temperature
CALIBRATED 4.8 MHz RC OSCILLATOR FREQUENCY vs. TEMPERATURE
5.1
5
F RC (MHz)
4.9
4.8
1.8 V
4.7
5.5 V
4.0 V
4.6
2.7 V
4.5
-60
-40
-20
0
20
40
60
80
100
Temperature (C)
149
2535I–AVR–05/08
Figure 19-54. Calibrated 4.8 MHz RC Oscillator Frequency vs. VCC
CALIBRATED 4.8 MHz RC OSCILLATOR FREQUENCY vs. VCC
5.2
85 ˚C
FRC (MHz)
5
4.8
25 ˚C
-40 ˚C
4.6
4.4
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
Figure 19-55. Calibrated 4.8 MHz RC Oscillator Frequency vs. Osccal Value
CALIBRATED 4.8 MHz RC OSCILLATOR FREQUENCY vs. OSCCAL VALUE
10
25 ˚C
9
8
FRC (MHz)
7
6
5
4
3
2
1
0
8
16
24
32
40
48
56
64
72
80
88
96
104
112
120 127
OSCCAL VALUE
150
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-56. 128 kHz Watchdog Oscillator Frequency vs. VCC
128 kHz WATCHDOG OSCILLATOR FREQUENCY vs. VCC
120
-40 ˚C
FRC (kHz)
115
25 ˚C
110
85 ˚C
105
100
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
Figure 19-57. 128 kHz Watchdog Oscillator Frequency vs. Temperature
128 kHz WATCHDOG OSCILLATOR FREQUENCY vs. TEMPERATURE
118
116
114
FRC (kHz)
112
110
1.8 V
108
2.7 V
4.0 V
5.5 V
106
104
102
100
-60
-40
-20
0
20
40
60
80
100
Temperature (C)
151
2535I–AVR–05/08
19.9
Current Consumption of Peripheral Units
Figure 19-58. Brownout Detector Current vs. VCC
BROWNOUT DETECTOR CURRENT vs. VCC
35
-40 ˚C
25 ˚C
85 ˚C
30
ICC (uA)
25
20
15
10
5
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
Figure 19-59. ADC Current vs. VCC
ADC CURRENT vs. VCC
350
-40 ˚C
300
25 ˚C
ICC (uA)
250
85 ˚C
200
150
100
50
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
152
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-60. Analog Comparator Current vs. VCC
ANALOG COMPARATOR CURRENT vs. VCC
140
ICC (uA)
-40 ˚C
120
25 ˚C
100
85 ˚C
80
60
40
20
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
5
5.5
VCC (V)
Figure 19-61. Programming Current vs. VCC
PROGRAMMING CURRENT vs. Vcc
4
3.5
3
ICC (mA)
2.5
2
1.5
1
-40 °C
25 °C
0.5
85 °C
0
1.5
2
2.5
3
3.5
4
4.5
VCC (V)
153
2535I–AVR–05/08
19.10 Current Consumption in Reset and Reset Pulse width
Figure 19-62. Reset Supply Current vs. VCC (0.1 - 1.0 MHz, Excluding Current through the
Reset Pull-up)
RESET SUPPLY CURRENT vs. VCC
0.1 - 1.0 MHz, EXCLUDING CURRENT THROUGH THE RESET PULL-UP
0.14
5.5 V
0.12
5.0 V
ICC (mA)
0.1
4.5 V
0.08
4.0 V
0.06
3.3 V
2.7 V
0.04
1.8 V
0.02
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Frequency (MHz)
Figure 19-63. Reset Supply Current vs. VCC (1 - 24 MHz, Excluding Current through the Reset
Pull-up)
RESET SUPPLY CURRENT vs. VCC
1 - 24 MHz, EXCLUDING CURRENT THROUGH THE RESET PULL-UP
ICC (mA)
3.5
3
5.5V
2.5
5.0V
2
4.5V
1.5
4.0V
1
3.3V
0.5
2.7V
1.8V
0
0
2
4
6
8
10
12
14
16
18
20
22
24
Frequency (MHz)
154
ATtiny13
2535I–AVR–05/08
ATtiny13
Figure 19-64. Reset Pulse Width vs. VCC
RESET PULSE WIDTH vs. V
CC
2500
Pulsewidth (ns)
2000
1500
1000
500
85 ºC
25 ºC
-40 ºC
0
1.8
2.1
2.5
2.7
3
3.3
3.5
4
4.5
5
5.5
6
VCC (V)
155
2535I–AVR–05/08
20. Register Summary
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Page
0x3F
SREG
I
T
H
S
V
N
Z
C
page 9
0x3E
Reserved
–
–
–
–
–
–
–
–
156
0x3D
SPL
SP[7:0]
0x3C
Reserved
–
page 11
0x3B
GIMSK
–
INT0
PCIE
–
–
–
–
–
page 46
0x3A
GIFR
–
INTF0
PCIF
–
–
–
–
–
page 47
0x39
TIMSK0
–
–
–
–
OCIE0B
OCIE0A
TOIE0
–
page 74
0x38
TIFR0
–
–
–
–
OCF0B
OCF0A
TOV0
0x37
SPMCSR
–
–
–
CTPB
RFLB
PGWRT
PGERS
–
SELF-
page 97
Timer/Counter – Output Compare Register A
page 75
0x36
OCR0A
0x35
MCUCR
–
PUD
SE
SM1
SM0
–
ISC01
ISC00
page 32
0x34
MCUSR
–
–
–
–
WDRF
BORF
EXTRF
PORF
page 41
0x33
TCCR0B
FOC0A
FOC0B
–
–
WGM02
CS02
CS01
CS00
page 72
0x32
TCNT0
Timer/Counter (8-bit)
page 73
0x31
OSCCAL
Oscillator Calibration Register
page 27
0x30
Reserved
–
0x2F
TCCR0A
0x2E
DWDR
COM0A1
DWDR[7:0]
0x2D
Reserved
–
0x2C
Reserved
–
0x2B
Reserved
–
0x2A
Reserved
–
0x29
OCR0B
Timer/Counter – Output Compare Register B
0x28
GTCCR
0x27
Reserved
TSM
COM0A0
–
COM0B1
–
COM0B0
–
–
page 74
–
WGM01
WGM00
page 69
page 96
page 74
–
–
–
PSR10
page 77
CLKPS3
CLKPS2
CLKPS1
CLKPS0
page 28
WDE
WDP2
WDP1
WDP0
page 41
–
CLKPCE
–
–
–
0x26
CLKPR
0x25
Reserved
–
0x24
Reserved
–
0x23
Reserved
–
0x22
Reserved
0x21
WDTCR
0x20
Reserved
–
WDTIF
WDTIE
WDP3
WDCE
–
–
0x1F
Reserved
0x1E
EEARL
0x1D
EEDR
0x1C
EECR
0x1B
Reserved
–
0x1A
Reserved
–
0x19
Reserved
0x18
PORTB
–
–
PORTB5
0x17
DDRB
–
–
0x16
PINB
–
0x15
PCMSK
0x14
DIDR0
0x13
Reserved
–
0x12
Reserved
–
0x11
Reserved
–
0x10
Reserved
–
0x0F
Reserved
–
0x0E
Reserved
–
0x0D
Reserved
–
0x0C
Reserved
–
0x0B
Reserved
–
0x0A
Reserved
–
0x09
Reserved
0x08
ACSR
ACD
ACBG
ACO
0x07
ADMUX
–
REFS0
0x06
ADCSRA
ADEN
ADSC
0x05
ADCH
ADC Data Register High Byte
0x04
ADCL
ADC Data Register Low Byte
0x03
ADCSRB
0x02
Reserved
–
0x01
Reserved
–
0x00
Reserved
–
–
–
EEPROM Address Register
page 20
EEPROM Data Register
–
–
EEPM1
EEPM0
page 20
EERIE
EEMPE
EEPE
EERE
page 21
PORTB4
PORTB3
PORTB2
PORTB1
PORTB0
page 56
DDB5
DDB4
DDB3
DDB2
DDB1
DDB0
page 56
–
PINB5
PINB4
PINB3
PINB2
PINB1
PINB0
page 57
–
–
PCINT5
PCINT4
PCINT3
PCINT2
PCINT1
PCINT0
page 47
–
–
ADC0D
ADC2D
ADC3D
ADC1D
AIN1D
AIN0D
page 80, page 94
ACI
ACIE
–
ACIS1
ACIS0
page 79
ADLAR
–
–
–
MUX1
MUX0
page 91
ADATE
ADIF
ADIE
ADPS2
ADPS1
ADPS0
page 92
–
–
–
ACME
–
–
–
page 93
page 93
ADTS2
ADTS1
ADTS0
page 94
ATtiny13
2535I–AVR–05/08
ATtiny13
Notes:
1. For compatibility with future devices, reserved bits should be written to zero if accessed. Reserved I/O memory addresses
should never be written.
2. I/O Registers within the address range 0x00 - 0x1F 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.ome of the Status Flags are
cleared by writing a logical one to them. Note that, unlike most other AVRs, the CBI and SBI instructions will only operation
the specified bit, and can therefore be used on registers containing such Status Flags. The CBI and SBI instructions work
with registers 0x00 to 0x1F only.
157
2535I–AVR–05/08
21. Instruction Set Summary
Mnemonics
Operands
Description
Operation
Flags
#Clocks
ARITHMETIC AND LOGIC INSTRUCTIONS
ADD
Rd, Rr
Add two Registers
Rd ← Rd + Rr
Z,C,N,V,H
1
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
1
SUBI
Rd, K
Subtract Constant from Register
Rd ← Rd - K
Z,C,N,V,H
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
AND
Rd, Rr
Logical AND Registers
Rd ← Rd • Rr
Z,N,V
1
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 ← 0xFF − Rd
Z,C,N,V
1
NEG
Rd
Two’s Complement
Rd ← 0x00 − 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 • (0xFF - 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
1
TST
Rd
Test for Zero or Minus
Rd ← Rd • Rd
Z,N,V
CLR
Rd
Clear Register
Rd ← Rd ⊕ Rd
Z,N,V
1
SER
Rd
Set Register
Rd ← 0xFF
None
1
RJMP
k
2
BRANCH INSTRUCTIONS
IJMP
RCALL
k
Relative Jump
PC ← PC + k + 1
None
Indirect Jump to (Z)
PC ← Z
None
2
Relative Subroutine Call
PC ← PC + k + 1
None
3
3
ICALL
Indirect Call to (Z)
PC ← Z
None
RET
Subroutine Return
PC ← STACK
None
4
RETI
Interrupt Return
PC ← STACK
I
4
CPSE
Rd,Rr
Compare, Skip if Equal
if (Rd = Rr) PC ← PC + 2 or 3
None
1/2/3
CP
Rd,Rr
Compare
Rd − Rr
Z, N,V,C,H
1
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
BIT AND BIT-TEST INSTRUCTIONS
158
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
ATtiny13
2535I–AVR–05/08
ATtiny13
Mnemonics
Operands
Description
Operation
Flags
ROR
Rd
Rotate Right Through Carry
Rd(7)←C,Rd(n)← Rd(n+1),C←Rd(0)
Z,C,N,V
#Clocks
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
1
BCLR
s
Flag Clear
SREG(s) ← 0
SREG(s)
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 Twos Complement Overflow.
V←1
V
1
CLV
Clear Twos 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
CLH
Set Half Carry Flag in SREG
Clear Half Carry Flag in SREG
H←1
H←0
H
H
1
1
1
DATA TRANSFER INSTRUCTIONS
MOV
Rd, Rr
Move Between Registers
Rd, Rr
Copy Register Word
Rd ← Rr
Rd+1:Rd ← Rr+1:Rr
None
MOVW
None
1
LDI
Rd, K
Load Immediate
Rd ← K
None
1
LD
Rd, X
Load Indirect
Rd ← (X)
None
2
LD
Rd, X+
Load Indirect and Post-Inc.
Rd ← (X), X ← X + 1
None
2
2
LD
Rd, - X
Load Indirect and Pre-Dec.
X ← X - 1, Rd ← (X)
None
LD
Rd, Y
Load Indirect
Rd ← (Y)
None
2
LD
Rd, Y+
Load Indirect and Post-Inc.
Rd ← (Y), Y ← Y + 1
None
2
2
LD
Rd, - Y
Load Indirect and Pre-Dec.
Y ← Y - 1, Rd ← (Y)
None
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-Inc.
Rd ← (Z), Z ← Z+1
None
2
LD
Rd, -Z
Load Indirect and Pre-Dec.
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-Inc.
(X) ← Rr, X ← X + 1
None
2
ST
- X, Rr
Store Indirect and Pre-Dec.
X ← X - 1, (X) ← Rr
None
2
ST
Y, Rr
Store Indirect
(Y) ← Rr
None
2
ST
Y+, Rr
Store Indirect and Post-Inc.
(Y) ← Rr, Y ← Y + 1
None
2
2
ST
- Y, Rr
Store Indirect and Pre-Dec.
Y ← Y - 1, (Y) ← Rr
None
STD
Y+q,Rr
Store Indirect with Displacement
(Y + q) ← Rr
None
2
ST
Z, Rr
Store Indirect
(Z) ← Rr
None
2
2
ST
Z+, Rr
Store Indirect and Post-Inc.
(Z) ← Rr, Z ← Z + 1
None
ST
-Z, Rr
Store Indirect and Pre-Dec.
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
LPM
LPM
Rd, Z
Load Program Memory
Rd ← (Z)
None
3
LPM
Rd, Z+
Load Program Memory and Post-Inc
Rd ← (Z), Z ← Z+1
None
3
Store Program Memory
(z) ← R1:R0
None
SPM
IN
Rd, P
In Port
Rd ← P
None
1
OUT
P, Rr
Out Port
P ← Rr
None
1
PUSH
Rr
Push Register on Stack
STACK ← Rr
None
2
POP
Rd
Pop Register from Stack
Rd ← STACK
None
2
MCU CONTROL INSTRUCTIONS
NOP
No Operation
None
1
SLEEP
Sleep
(see specific descr. for Sleep function)
None
1
WDR
BREAK
Watchdog Reset
Break
(see specific descr. for WDR/Timer)
For On-chip Debug Only
None
None
1
N/A
159
2535I–AVR–05/08
22. Ordering Information
Speed (MHz) (3)
10
20
Notes:
Power Supply
Ordering Code (2)
Package (1)
Operation Range
1.8 - 5.5
ATtiny13V-10PU
ATtiny13V-10SU
ATtiny13V-10SSU
ATtiny13V-10MU
ATtiny13V-10MMU
8P3
8S2
S8S1
20M1
10M1
Industrial
(-40°C to 85°C)
2.7 - 5.5
ATtiny13-20PU
ATtiny13-20SU
ATtiny13-20SSU
ATtiny13-20MU
ATtiny13-20MMU
8P3
8S2
S8S1
20M1
10M1
Industrial
(-40°C to 85°C)
1. This device can also be supplied in wafer form. Please contact your local Atmel sales office for detailed ordering information
and minimum quantities.
2. Pb-free packaging alternative, complies to the European Directive for Restriction of Hazardous Substances (RoHS directive). Also Halide free and fully Green
3. For Speed vs. VCC, see “Speed Grades” on page 117.
Package Type
8P3
8-lead, 0.300" Wide, Plastic Dual Inline Package (PDIP)
8S2
8-lead, 0.209" Wide, Plastic Small Outline Package (EIAJ SOIC)
S8S1
8-lead, 0.150" Wide, Plastic Gull-Wing Small Outline (JEDEC SOIC)
20M1
20-pad, 4 x 4 x 0.8 mm Body, Lead Pitch 0.50 mm, Micro Lead Frame Package (MLF)
10M1
10-pad, 3 x 3 x 1 mm Body, Lead Pitch 0.50 mm, Micro Lead Frame Package (MLF)
160
ATtiny13
2535I–AVR–05/08
ATtiny13
23. Packaging Information
23.1
8P3
E
1
E1
N
Top View
c
eA
End View
COMMON DIMENSIONS
(Unit of Measure = inches)
D
e
D1
A2 A
SYMBOL
MIN
NOM
A
b2
b3
b
4 PLCS
Side View
L
0.210
NOTE
2
A2
0.115
0.130
0.195
b
0.014
0.018
0.022
5
b2
0.045
0.060
0.070
6
b3
0.030
0.039
0.045
6
c
0.008
0.010
0.014
D
0.355
0.365
0.400
D1
0.005
E
0.300
0.310
0.325
4
E1
0.240
0.250
0.280
3
0.100 BSC
eA
0.300 BSC
0.115
3
3
e
L
Notes:
MAX
0.130
4
0.150
2
1. This drawing is for general information only; refer to JEDEC Drawing MS-001, Variation BA for additional information.
2. Dimensions A and L are measured with the package seated in JEDEC seating plane Gauge GS-3.
3. D, D1 and E1 dimensions do not include mold Flash or protrusions. Mold Flash or protrusions shall not exceed 0.010 inch.
4. E and eA measured with the leads constrained to be perpendicular to datum.
5. Pointed or rounded lead tips are preferred to ease insertion.
6. b2 and b3 maximum dimensions do not include Dambar protrusions. Dambar protrusions shall not exceed 0.010 (0.25 mm).
01/09/02
R
2325 Orchard Parkway
San Jose, CA 95131
TITLE
8P3, 8-lead, 0.300" Wide Body, Plastic Dual
In-line Package (PDIP)
DRAWING NO.
REV.
8P3
B
161
2535I–AVR–05/08
23.2
8S2
C
1
E
E1
L
N
θ
TOP VIEW
END VIEW
e
b
COMMON DIMENSIONS
(Unit of Measure = mm)
A
SYMBOL
A1
D
SIDE VIEW
NOM
MAX
NOTE
A
1.70
2.16
A1
0.05
0.25
b
0.35
0.48
5
C
0.15
0.35
5
D
5.13
5.35
E1
5.18
5.40
E
7.70
8.26
L
0.51
0.85
θ
0°
e
Notes: 1.
2.
3.
4.
5.
MIN
2, 3
8°
1.27 BSC
4
This drawing is for general information only; refer to EIAJ Drawing EDR-7320 for additional information.
Mismatch of the upper and lower dies and resin burrs are not included.
It is recommended that upper and lower cavities be equal. If they are different, the larger dimension shall be regarded.
Determines the true geometric position.
Values b,C apply to plated terminal. The standard thickness of the plating layer shall measure between 0.007 to .021 mm.
4/7/06
R
162
2325 Orchard Parkway
San Jose, CA 95131
TITLE
8S2, 8-lead, 0.209" Body, Plastic Small
Outline Package (EIAJ)
DRAWING NO.
8S2
REV.
D
ATtiny13
2535I–AVR–05/08
ATtiny13
23.3
S8S1
3
2
1
H
N
Top View
e
B
A
D
COMMON DIMENSIONS
(Unit of Measure = mm)
Side View
A2
C
L
SYMBOL
MIN
NOM
MAX
A
–
–
1.75
B
–
–
0.51
C
–
–
0.25
D
–
–
5.00
E
–
–
4.00
e
E
End View
NOTE
1.27 BSC
H
–
–
6.20
L
–
–
1.27
Note: This drawing is for general information only. Refer to JEDEC Drawing MS-012 for proper dimensions, tolerances, datums, etc.
10/10/01
R
2325 Orchard Parkway
San Jose, CA 95131
TITLE
8S1, 8-lead (0.150" Wide Body), Plastic Gull Wing
Small Outline (JEDEC SOIC)
DRAWING NO.
REV.
8S1
A
163
2535I–AVR–05/08
23.4
20M1
D
1
Pin 1 ID
2
SIDE VIEW
E
3
TOP VIEW
A2
D2
A1
A
0.08
1
2
Pin #1
Notch
(0.20 R)
3
COMMON DIMENSIONS
(Unit of Measure = mm)
E2
b
L
e
BOTTOM VIEW
SYMBOL
MIN
NOM
MAX
A
0.70
0.75
0.80
A1
–
0.01
0.05
A2
b
0.18
D
D2
E2
L
0.23
0.30
4.00 BSC
2.45
2.60
2.75
4.00 BSC
2.45
e
Reference JEDEC Standard MO-220, Fig. 1 (SAW Singulation) WGGD-5.
NOTE
0.20 REF
E
Note:
C
2.60
2.75
0.50 BSC
0.35
0.40
0.55
10/27/04
R
164
2325 Orchard Parkway
San Jose, CA 95131
TITLE
20M1, 20-pad, 4 x 4 x 0.8 mm Body, Lead Pitch 0.50 mm,
2.6 mm Exposed Pad, Micro Lead Frame Package (MLF)
DRAWING NO.
20M1
REV.
A
ATtiny13
2535I–AVR–05/08
ATtiny13
23.5
10M1
D
y
Pin 1 ID
SIDE VIEW
E
TOP VIEW
A1
A
D1
K
COMMON DIMENSIONS
(Unit of Measure = mm)
1
2
b
E1
e
SYMBOL
MIN
NOM
MAX
A
0.80
0.90
1.00
A1
0.00
0.02
0.05
b
0.18
0.25
0.30
D
2.90
3.00
3.10
D1
1.40
–
1.75
E
2.90
3.00
3.10
E1
2.20
–
2.70
e
L
BOTTOM VIEW
NOTE
0.50
L
0.30
–
0.50
y
–
–
0.08
K
0.20
–
–
Notes: 1. This package conforms to JEDEC reference MO-229C, Variation VEED-5.
2. The terminal #1 ID is a Lasser-marked Feature.
R
TITLE
2325 Orchard Parkway 10M1, 10-pad, 3 x 3 x 1.0 mm Body, Lead Pitch 0.50 mm,
San Jose, CA 95131
1.64 x 2.60 mm Exposed Pad, Micro Lead Frame Package
7/7/06
DRAWING NO.
REV.
10M1
A
165
2535I–AVR–05/08
24. Errata
The revision letter in this section refers to the revision of the ATtiny13 device.
24.1
ATtiny13 Rev. D
• EEPROM can not be written below 1.9 Volt
1. EEPROM can not be written below 1.9 Volt
Writing the EEPROM at VCC below 1.9 volts might fail.
Problem Fix/Workaround
Do not write the EEPROM when VCC is below 1.9 volts.
24.2
ATtiny13 Rev. C
Revision C has not been sampled.
24.3
ATtiny13 Rev. B
•
•
•
•
•
•
24.3.1
Wrong values read after Erase Only operation
High Voltage Serial Programming Flash, EEPROM, Fuse and Lock Bits may fail
Device may lock for further programming
debugWIRE communication not blocked by lock-bits
Watchdog Timer Interrupt disabled
EEPROM can not be written below 1.9 Volt
Wrong values read after Erase Only operation
At supply voltages below 2.7 V, an EEPROM location that is erased by the Erase Only operation may read as programmed (0x00).
Problem Fix/Workaround
If it is necessary to read an EEPROM location after Erase Only, use an Atomic Write operation with 0xFF as data in order to erase a location. In any case, the Write Only operation can
be used as intended. Thus no special considerations are needed as long as the erased location is not read before it is programmed.
24.3.2
High Voltage Serial Programming Flash, EEPROM, Fuse and Lock Bits may fail
Writing to any of these locations and bits may in some occasions fail.
Problem Fix/Workaround
After a writing has been initiated, always observe the RDY/BSY signal. If the writing should
fail, rewrite until the RDY/BSY verifies a correct writing. This will be fixed in revision D.
24.3.3
Device may lock for further programming
Special combinations of fuse bits will lock the device for further programming effectively
turning it into an OTP device. The following combinations of settings/fuse bits will cause this
effect:
– 128 kHz internal oscillator (CKSEL[1..0] = 11), shortest start-up time
(SUT[1..0] = 00), Debugwire enabled (DWEN = 0) or Reset disabled RSTDISBL = 0.
– 9.6 MHz internal oscillator (CKSEL[1..0] = 10), shortest start-up time
(SUT[1..0] = 00), Debugwire enabled (DWEN = 0) or Reset disabled RSTDISBL = 0.
166
ATtiny13
2535I–AVR–05/08
ATtiny13
– 4.8 MHz internal oscillator (CKSEL[1..0] = 01), shortest start-up time
(SUT[1..0] = 00), Debugwire enabled (DWEN = 0) or Reset disabled RSTDISBL = 0.
Problem fix/ Workaround
Avoid the above fuse combinations. Selecting longer start-up time will eliminate the problem.
24.3.4
debugWIRE communication not blocked by lock-bits
When debugWIRE on-chip debug is enabled (DWEN = 0), the contents of program memory
and EEPROM data memory can be read even if the lock-bits are set to block further reading
of the device.
Problem fix/ Workaround
Do not ship products with on-chip debug of the tiny13 enabled.
24.3.5
Watchdog Timer Interrupt disabled
If the watchdog timer interrupt flag is not cleared before a new timeout occurs, the watchdog
will be disabled, and the interrupt flag will automatically be cleared. This is only applicable in
interrupt only mode. If the Watchdog is configured to reset the device in the watchdog timeout following an interrupt, the device works correctly.
Problem fix / Workaround
Make sure there is enough time to always service the first timeout event before a new
watchdog timeout occurs. This is done by selecting a long enough time-out period.
24.3.6
EEPROM can not be written below 1.9 Volt
Writing the EEPROM at VCC below 1.9 volts might fail.
Problem Fix/Workaround
Do not write the EEPROM when VCC is below 1.9 volts.
24.4
ATtiny13 Rev. A
Revision A has not been sampled.
167
2535I–AVR–05/08
25. Datasheet Revision History
Please note that page numbers in this section are referring to this document.
25.1
Rev. 2535I-05/08
1. Updated document template, layout and paragraph formats.
2. Updated “Features” on page 1.
3. Created Sections:
– “Calibrated Internal RC Oscillator Accuracy” on page 118
– “Analog Comparator Characteristics” on page 119
4. Updated Sections:
– “System Clock and Clock Options” on page 23
– “Calibrated Internal 4.8/9.6 MHz Oscillator” on page 25
– “External Interrupts” on page 45
– “Analog Noise Canceling Techniques” on page 88
– “Limitations of debugWIRE” on page 96
– “Reading Fuse and Lock Bits from Firmware” on page 99
– “Fuse Bytes” on page 103
– “Calibration Bytes” on page 104
– “High-Voltage Serial Programming” on page 108
– “Ordering Information” on page 160
5. Updated Figure:
– “Analog Input Circuitry” on page 87
– “High-voltage Serial Programming Timing” on page 122
6. Moved Figures:
– “Serial Programming Timing” on page 121
– “Serial Programming Waveform” on page 121
– “High-voltage Serial Programming Timing” on page 122
7. Updated Tables:
– “DC Characteristics, TA = -40×C to 85×C” on page 115
– “Serial Programming Characteristics, TA = -40×C to 85×C, VCC = 1.8 - 5.5V (Unless
Otherwise Noted)” on page 121
8. Moved Tables:
– “Serial Programming Instruction Set” on page 107
– “Serial Programming Characteristics, TA = -40×C to 85×C, VCC = 1.8 - 5.5V (Unless
Otherwise Noted)” on page 121
– “High-voltage Serial Programming Characteristics TA = 25×C, VCC = 5.0V ± 10%
(Unless otherwise noted)” on page 122
9. Updated Register Description for Sections:
– “TCCR0A – Timer/Counter Control Register A” on page 69
– “DIDR0 – Digital Input Disable Register 0” on page 94
10. Updated description in Step 1. on page 106.
11. Changed device status to “Not Recommended for New Designs”.
168
ATtiny13
2535I–AVR–05/08
ATtiny13
25.2
Rev. 2535H-10/07
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
25.3
Rev. 2535G-01/07
1.
2.
3.
4.
5.
6.
7.
8.
9.
25.4
Removed Preliminary.
Updated Table 7-1 on page 30, Table 8-1 on page 42,Table 18-8 on page 121.
Removed Note from Table 7-1 on page 30.
Updated “Bit 6 – ACBG: Analog Comparator Bandgap Select” on page 79.
Updated “Prescaling and Conversion Timing” on page 83.
Updated Figure 18-4 on page 121.
Updated “DC Characteristics” on page 115.
Updated “Ordering Information” on page 160.
Updated “Packaging Information” on page 161.
Rev. 2535F-04/06
1.
25.5
Updated “Features” on page 1.
Updated “Pin Configurations” on page 2.
Added “Data Retention” on page 6.
Updated “Assembly Code Example(1)” on page 39.
Updated Table 21 in “Alternate Functions of Port B” on page 54.
Updated Bit 5 description in “GIMSK – General Interrupt Mask Register” on page 46.
Updated “ADC Voltage Reference” on page 87.
Updated “Calibration Bytes” on page 104.
Updated “Read Calibration Byte” on page 108.
Updated Table 51 in “Serial Programming Characteristics” on page 121.
Updated Algorithm in “High-Voltage Serial Programming Algorithm” on page 109.
Updated “Read Calibration Byte” on page 112.
Updated values in “External Clock Drive” on page 118.
Updated “Ordering Information” on page 160.
Updated “Packaging Information” on page 161.
Revision not published.
Rev. 2535E-10/04
1.
2.
3.
2.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Bits EEMWE/EEWE changed to EEMPE/EEPE in document.
Updated “Pinout ATtiny13/ATtiny13V” on page 2.
Updated “Write Fuse Low Bits” in Table 17-13 on page 110, Table 18-3 on page 118.
Added “Pin Change Interrupt Timing” on page 45.
Updated “GIMSK – General Interrupt Mask Register” on page 46.
Updated “PCMSK – Pin Change Mask Register” on page 47.
Updated item 4 in “Serial Programming Algorithm” on page 106.
Updated “High-Voltage Serial Programming Algorithm” on page 109.
Updated “DC Characteristics” on page 115.
Updated “Typical Characteristics” on page 122.
Updated “Ordering Information” on page 160.
Updated “Packaging Information” on page 161.
Updated “Errata” on page 166.
169
2535I–AVR–05/08
25.6
Rev. 2535D-04/04
1.
25.7
25.8
2.
3.
4.
Maximum Speed Grades changed
- 12MHz to 10MHz
- 24MHz to 20MHz
Updated “Serial Programming Instruction Set” on page 107.
Updated “Speed Grades” on page 117
Updated “Ordering Information” on page 160
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
C-code examples updated to use legal IAR syntax.
Replaced occurrences of WDIF with WDTIF and WDIE with WDTIE.
Updated “Stack Pointer” on page 11.
Updated “Calibrated Internal 4.8/9.6 MHz Oscillator” on page 25.
Updated “OSCCAL – Oscillator Calibration Register” on page 27.
Updated typo in introduction on “Watchdog Timer” on page 37.
Updated “ADC Conversion Time” on page 86.
Updated “Serial Programming” on page 105.
Updated “Electrical Characteristics” on page 115.
Updated “Ordering Information” on page 160.
Removed rev. C from “Errata” on page 166.
2535C-02/04
Rev. 2535B-01/04
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
25.9
Rev. 2535A-06/03
1.
170
Updated Figure 2-1 on page 4.
Updated Table 7-1 on page 30, Table 8-1 on page 42, Table 14-2 on page 91 and
Table 18-3 on page 118.
Updated “Calibrated Internal 4.8/9.6 MHz Oscillator” on page 25.
Updated the whole “Watchdog Timer” on page 37.
Updated Figure 17-1 on page 105 and Figure 17-2 on page 108.
Updated registers “MCUCR – MCU Control Register” on page 56, “TCCR0B –
Timer/Counter Control Register B” on page 72 and “DIDR0 – Digital Input Disable Register 0” on page 80.
Updated Absolute Maximum Ratings and DC Characteristics in “Electrical Characteristics” on page 115.
Added “Speed Grades” on page 117
Updated “” on page 120.
Updated “Typical Characteristics” on page 123.
Updated “Ordering Information” on page 160.
Updated “Packaging Information” on page 161.
Updated “Errata” on page 166.
Changed instances of EEAR to EEARL.
Initial Revision.
ATtiny13
2535I–AVR–05/08
ATtiny13
Table of Contents
Features ..................................................................................................... 1
1
Pin Configurations ................................................................................... 2
1.1
2
Overview ................................................................................................... 4
2.1
3
4
5
6
7
Pin Descriptions .................................................................................................3
Block Diagram ...................................................................................................4
About ......................................................................................................... 6
3.1
Resources .........................................................................................................6
3.2
Code Examples .................................................................................................6
3.3
Data Retention ...................................................................................................6
CPU Core .................................................................................................. 7
4.1
Architectural Overview .......................................................................................7
4.2
ALU – Arithmetic Logic Unit ...............................................................................8
4.3
Status Register ..................................................................................................8
4.4
General Purpose Register File ........................................................................10
4.5
Stack Pointer ...................................................................................................11
4.6
Instruction Execution Timing ...........................................................................12
4.7
Reset and Interrupt Handling ...........................................................................12
Memories ................................................................................................ 15
5.1
In-System Reprogrammable Flash Program Memory .....................................15
5.2
SRAM Data Memory ........................................................................................15
5.3
EEPROM Data Memory ..................................................................................16
5.4
I/O Memory ......................................................................................................20
5.5
Register Description ........................................................................................20
System Clock and Clock Options ......................................................... 23
6.1
Clock Systems and their Distribution ...............................................................23
6.2
Clock Sources .................................................................................................24
6.3
System Clock Prescaler ..................................................................................26
6.4
Register Description ........................................................................................27
Power Management and Sleep Modes ................................................. 30
7.1
Sleep Modes ....................................................................................................30
7.2
Minimizing Power Consumption ......................................................................31
7.3
Register Description ........................................................................................32
i
2535I–AVR–05/08
8
9
System Control and Reset .................................................................... 34
8.1
Reset Sources .................................................................................................35
8.2
Internal Voltage Reference ..............................................................................37
8.3
Watchdog Timer ..............................................................................................37
8.4
Register Description ........................................................................................41
Interrupts ................................................................................................ 44
9.1
Interrupt Vectors ..............................................................................................44
9.2
External Interrupts ...........................................................................................45
9.3
Register Description ........................................................................................46
10 I/O Ports .................................................................................................. 48
10.1
Overview ..........................................................................................................48
10.2
Ports as General Digital I/O .............................................................................49
10.3
Alternate Port Functions ..................................................................................53
10.4
Register Description ........................................................................................56
11 8-bit Timer/Counter0 with PWM ............................................................ 58
11.1
Features ..........................................................................................................58
11.2
Overview ..........................................................................................................58
11.3
Timer/Counter Clock Sources .........................................................................59
11.4
Counter Unit ....................................................................................................59
11.5
Output Compare Unit .......................................................................................60
11.6
Compare Match Output Unit ............................................................................62
11.7
Modes of Operation .........................................................................................63
11.8
Timer/Counter Timing Diagrams .....................................................................67
11.9
Register Description ........................................................................................69
12 Timer/Counter Prescaler ....................................................................... 76
12.1
Overview ..........................................................................................................76
12.2
Prescaler Reset ...............................................................................................76
12.3
External Clock Source .....................................................................................76
12.4
Register Description. .......................................................................................77
13 Analog Comparator ............................................................................... 78
13.1
Analog Comparator Multiplexed Input .............................................................78
13.2
Register Description ........................................................................................79
14 Analog to Digital Converter .................................................................. 81
14.1
ii
Features ..........................................................................................................81
ATtiny13
2535I–AVR–05/08
ATtiny13
14.2
Overview ..........................................................................................................81
14.3
Operation .........................................................................................................82
14.4
Starting a Conversion ......................................................................................82
14.5
Prescaling and Conversion Timing ..................................................................83
14.6
Changing Channel or Reference Selection .....................................................86
14.7
ADC Noise Canceler .......................................................................................87
14.8
Analog Input Circuitry ......................................................................................87
14.9
Analog Noise Canceling Techniques ...............................................................88
14.10
ADC Accuracy Definitions ...............................................................................88
14.11
ADC Conversion Result ...................................................................................91
14.12
Register Description ........................................................................................91
15 debugWIRE On-chip Debug System .................................................... 95
15.1
Features ..........................................................................................................95
15.2
Overview ..........................................................................................................95
15.3
Physical Interface ............................................................................................95
15.4
Software Break Points .....................................................................................96
15.5
Limitations of debugWIRE ...............................................................................96
15.6
Register Description ........................................................................................96
16 Self-Programming the Flash ................................................................. 97
16.1
Performing Page Erase by SPM ......................................................................97
16.2
Filling the Temporary Buffer (Page Loading) ...................................................97
16.3
Performing a Page Write .................................................................................98
16.4
Addressing the Flash During Self-Programming .............................................98
16.5
EEPROM Write Prevents Writing to SPMCSR ................................................99
16.6
Reading Fuse and Lock Bits from Firmware ...................................................99
16.7
Preventing Flash Corruption ..........................................................................100
16.8
Programming Time for Flash when Using SPM ............................................100
16.9
Register Description ......................................................................................101
17 Memory Programming ......................................................................... 102
17.1
Program And Data Memory Lock Bits ...........................................................102
17.2
Fuse Bytes .....................................................................................................103
17.3
Calibration Bytes ...........................................................................................104
17.4
Signature Bytes .............................................................................................104
17.5
Page Size ......................................................................................................104
17.6
Serial Programming .......................................................................................105
iii
2535I–AVR–05/08
17.7
High-Voltage Serial Programming .................................................................108
17.8
Considerations for Efficient Programming .....................................................112
18 Electrical Characteristics .................................................................... 115
18.1
Absolute Maximum Ratings* .........................................................................115
18.2
DC Characteristics .........................................................................................115
18.3
Speed Grades ...............................................................................................117
18.4
Clock Characteristics .....................................................................................118
18.5
System and Reset Characteristics ................................................................119
18.6
Analog Comparator Characteristics ...............................................................119
18.7
ADC Characteristics ......................................................................................120
18.8
Serial Programming Characteristics ..............................................................121
18.9
High-voltage Serial Programming Characteristics .........................................122
19 Typical Characteristics ........................................................................ 123
19.1
Active Supply Current ....................................................................................123
19.2
Idle Supply Current ........................................................................................126
19.3
Power-Down Supply Current .........................................................................129
19.4
Pin Pull-up .....................................................................................................130
19.5
Pin Driver Strength ........................................................................................132
19.6
Pin Thresholds and Hysteresis ......................................................................141
19.7
BOD Thresholds and Analog Comparator Offset ..........................................146
19.8
Internal Oscillator Speed ...............................................................................148
19.9
Current Consumption of Peripheral Units ......................................................152
19.10
Current Consumption in Reset and Reset Pulse width .................................154
20 Register Summary ............................................................................... 156
21 Instruction Set Summary .................................................................... 158
22 Ordering Information ........................................................................... 160
23 Packaging Information ........................................................................ 161
23.1
8P3 ................................................................................................................161
23.2
8S2 ................................................................................................................162
23.3
S8S1 ..............................................................................................................163
23.4
20M1 ..............................................................................................................164
23.5
10M1 ..............................................................................................................165
24 Errata ..................................................................................................... 166
24.1
iv
ATtiny13 Rev. D ............................................................................................166
ATtiny13
2535I–AVR–05/08
ATtiny13
24.2
ATtiny13 Rev. C ............................................................................................166
24.3
ATtiny13 Rev. B .............................................................................................166
24.4
ATtiny13 Rev. A .............................................................................................167
25 Datasheet Revision History ................................................................ 168
25.1
Rev. 2535I-05/08 ...........................................................................................168
25.2
Rev. 2535H-10/07 .........................................................................................169
25.3
Rev. 2535G-01/07 .........................................................................................169
25.4
Rev. 2535F-04/06 ..........................................................................................169
25.5
Rev. 2535E-10/04 ..........................................................................................169
25.6
Rev. 2535D-04/04 .........................................................................................170
25.7
2535C-02/04 ..................................................................................................170
25.8
Rev. 2535B-01/04 ..........................................................................................170
25.9
Rev. 2535A-06/03 ..........................................................................................170
Table of Contents....................................................................................... i
v
2535I–AVR–05/08
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2535I–AVR–05/08