ATMEL ATTINY9 Atmel 8-bit avr microcontroller Datasheet

Atmel 8-bit AVR Microcontroller with 512/1024
Bytes In-System Programmable Flash
ATtiny4 / ATtiny5 / ATtiny9 / ATtiny10
Features
• High Performance, Low Power AVR® 8-Bit Microcontroller
• Advanced RISC Architecture
•
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•
•
•
•
•
•
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– 54 Powerful Instructions – Most Single Clock Cycle Execution
– 16 x 8 General Purpose Working Registers
– Fully Static Operation
– Up to 12 MIPS Throughput at 12 MHz
Non-volatile Program and Data Memories
– 512/1024 Bytes of In-System Programmable Flash Program Memory
– 32 Bytes Internal SRAM
– Flash Write/Erase Cycles: 10,000
– Data Retention: 20 Years at 85oC / 100 Years at 25oC
Peripheral Features
– QTouch® Library Support for Capacitive Touch Sensing (1 Channel)
– One 16-bit Timer/Counter with Prescaler and Two PWM Channels
– Programmable Watchdog Timer with Separate On-chip Oscillator
– 4-channel, 8-bit Analog to Digital Converter (ATtiny5/10, only)
– On-chip Analog Comparator
Special Microcontroller Features
– In-System Programmable (at 5V, only)
– External and Internal Interrupt Sources
– Low Power Idle, ADC Noise Reduction, and Power-down Modes
– Enhanced Power-on Reset Circuit
– Programmable Supply Voltage Level Monitor with Interrupt and Reset
– Internal Calibrated Oscillator
I/O and Packages
– Four Programmable I/O Lines
– 6-pin SOT and 8-pad UDFN
Operating Voltage:
– 1.8 – 5.5V
Programming Voltage:
– 5V
Speed Grade
– 0 – 4 MHz @ 1.8 – 5.5V
– 0 – 8 MHz @ 2.7 – 5.5V
– 0 – 12 MHz @ 4.5 – 5.5V
Industrial and Extended Temperature Ranges
Low Power Consumption
– Active Mode:
• 200µA at 1MHz and 1.8V
– Idle Mode:
• 25µA at 1MHz and 1.8V
– Power-down Mode:
• < 0.1µA at 1.8V
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1. Pin Configurations
Figure 1-1.
Pinout of ATtiny4/5/9/10
SOT-23
(PCINT0/TPIDATA/OC0A/ADC0/AIN0) PB0
GND
(PCINT1/TPICLK/CLKI/ICP0/OC0B/ADC1/AIN1) PB1
1
2
3
6
5
4
PB3 (RESET/PCINT3/ADC3)
VCC
PB2 (T0/CLKO/PCINT2/INT0/ADC2)
UDFN
(PCINT1/TPICLK/CLKI/ICP0/OC0B/ADC1/AIN1) PB1
NC
NC
GND
1
2
3
4
8
7
6
5
PB2 (T0/CLKO/PCINT2/INT0/ADC2)
VCC
PB3 (RESET/PCINT3/ADC3)
PB0 (AIN0/ADC0/OC0A/TPIDATA/PCINT0)
1.1
Pin Description
1.1.1
VCC
Supply voltage.
1.1.2
GND
Ground.
1.1.3
Port B (PB3..PB0)
This is a 4-bit, bi-directional I/O port with internal pull-up resistors, individually selectable for each bit. The output
buffers have symmetrical drive characteristics, with both high sink and source capability. As inputs, the port pins
that are externally pulled low will source current if pull-up resistors are activated. Port pins are tri-stated when a
reset condition becomes active, even if the clock is not running.
The port also serves the functions of various special features of the ATtiny4/5/9/10, as listed on page 36.
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 and provided the reset pin has not been disabled. The minimum pulse length is given in Table 16-4
on page 118. 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
ATtiny4/5/9/10 are low-power CMOS 8-bit microcontrollers based on the compact AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the ATtiny4/5/9/10 achieve throughputs
approaching 1 MIPS per MHz, allowing the system designer to optimize power consumption versus processing
speed.
Figure 2-1.
Block Diagram
VCC
RESET
PROGRAMMING
LOGIC
PROGRAM
COUNTER
INTERNAL
OSCILLATOR
CALIBRATED
OSCILLATOR
PROGRAM
FLASH
STACK
POINTER
WATCHDOG
TIMER
TIMING AND
CONTROL
INSTRUCTION
REGISTER
SRAM
RESET FLAG
REGISTER
INSTRUCTION
DECODER
MCU STATUS
REGISTER
GENERAL
PURPOSE
REGISTERS
CONTROL
LINES
TIMER/
COUNTER0
X
Y
Z
INTERRUPT
UNIT
ALU
STATUS
REGISTER
ISP
INTERFACE
8-BIT DATA BUS
ANALOG
COMPARATOR
DIRECTION
REG. PORT B
DATA REGISTER
PORT B
ADC
DRIVERS
PORT B
PB3:0
GND
The AVR core combines a rich instruction set with 16 general purpose working registers and system registers. All
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 compact and code efficient while achieving throughputs up to ten times faster than conventional CISC microcontrollers.
The ATtiny4/5/9/10 provide the following features: 512/1024 byte of In-System Programmable Flash, 32 bytes of
SRAM, four general purpose I/O lines, 16 general purpose working registers, a 16-bit timer/counter with two PWM
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channels, internal and external interrupts, a programmable watchdog timer with internal oscillator, an internal calibrated oscillator, and four software selectable power saving modes. ATtiny5/10 are also equipped with a fourchannel, 8-bit Analog to Digital Converter (ADC).
Idle mode stops the CPU while allowing the SRAM, timer/counter, ADC (ATtiny5/10, only), analog comparator, and
interrupt system to continue functioning. ADC Noise Reduction mode minimizes switching noise during ADC conversions by stopping the CPU and all I/O modules except the ADC. In Power-down mode registers keep their
contents and all chip functions are disabled until the next interrupt or hardware reset. In Standby mode, the oscillator is running while the rest of the device is sleeping, allowing very fast start-up combined with low power
consumption.
The device is manufactured using Atmel’s high density non-volatile memory technology. The on-chip, in-system
programmable Flash allows program memory to be re-programmed in-system by a conventional, non-volatile
memory programmer.
The ATtiny4/5/9/10 AVR are supported by a suite of program and system development tools, including macro
assemblers and evaluation kits.
2.1
Comparison of ATtiny4, ATtiny5, ATtiny9 and ATtiny10
A comparison of the devices is shown in Table 2-1.
Table 2-1.
Differences between ATtiny4, ATtiny5, ATtiny9 and ATtiny10
Device
Flash
ADC
Signature
ATtiny4
512 bytes
No
0x1E 0x8F 0x0A
ATtiny5
512 bytes
Yes
0x1E 0x8F 0x09
ATtiny9
1024 bytes
No
0x1E 0x90 0x08
ATtiny10
1024 bytes
Yes
0x1E 0x90 0x03
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3. General Information
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/microcontroller/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
Capacitive Touch Sensing
Atmel QTouch Library provides a simple to use solution for touch sensitive interfaces on Atmel AVR microcontrollers. The QTouch Library includes support for QTouch® and QMatrix® acquisition methods.
Touch sensing is easily added to any application by linking the QTouch Library and using the Application Programming Interface (API) of the library to define the touch channels and sensors. The application then calls the API to
retrieve channel information and determine the state of the touch sensor.
The QTouch Library is free and can be downloaded from the Atmel website. For more information and details of
implementation, refer to the QTouch Library User Guide – also available from the Atmel website.
3.4
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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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.
Architectural Overview
Figure 4-1.
Block Diagram of the AVR Architecture
Data Bus 8-bit
Flash
Program
Memory
Status
and Control
Program
Counter
16 x 8
General
Purpose
Registrers
Instruction
Decoder
Control Lines
Indirect Addressing
Instruction
Register
Direct Addressing
4.1
Interrupt
Unit
Watchdog
Timer
ALU
Analog
Comparator
ADC
Data
SRAM
Timer/Counter 0
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.
The fast-access Register File contains 16 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.
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Six of the 16 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, capable of directly addressing
the whole address space. Most AVR instructions have a single 16-bit word format but 32-bit wide instructions also
exist. The actual instruction set varies, as some devices only implement a part of the instruction set.
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 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 four 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 as the data space locations, 0x0000 - 0x003F.
4.2
ALU – Arithmetic Logic Unit
The high-performance AVR ALU operates in direct connection with all the 16 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 bitfunctions. Some implementations of the architecture also provide a powerful multiplier supporting both
signed/unsigned multiplication and fractional format. See document “AVR Instruction Set” and section “Instruction
Set Summary” on page 150 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 document “AVR Instruction Set” and section “Instruction Set Summary” on page 150. 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.
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
• One 16-bit output operand and one 16-bit result input
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Figure 4-2 below shows the structure of the 16 general purpose working registers in the CPU.
Figure 4-2.
AVR CPU General Purpose Working Registers
7
0
R16
R17
Note:
General
R18
Purpose
…
Working
R26
X-register Low Byte
Registers
R27
X-register High Byte
R28
Y-register Low Byte
R29
Y-register High Byte
R30
Z-register Low Byte
R31
Z-register High Byte
A typical implementation of the AVR register file includes 32 general prupose registers but ATtiny4/5/9/10 implement
only 16 registers. For reasons of compatibility the registers are numbered R16...R31, not R0...R15.
Most of the instructions operating on the Register File have direct access to all registers, and most of them are single cycle instructions.
4.4.1
The X-register, Y-register, and Z-register
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.
Figure 4-3.
The X-, Y-, and Z-registers
15
X-register
XH
7
XL
0
7
R27
15
Y-register
YL
0
7
R29
15
Z-register
0
ZL
0
R31
0
R28
ZH
7
0
R26
YH
7
0
7
0
0
R30
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In different addressing modes these address registers function as automatic increment and automatic decrement
(see document “AVR Instruction Set” and section “Instruction Set Summary” on page 150 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 must be defined by the program before any subroutine calls are executed or interrupts are enabled. The Stack Pointer must be set to point above 0x40. 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.
4.6
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.
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 4-4 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 4-5 shows the internal timing concept for the Register File. In a single clock cycle an ALU operation using
two register operands is executed, and the result is stored back to the destination register.
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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 35. The list also determines the priority levels of the
different interrupts. The lower the address the higher is the priority level. RESET has the highest priority, and next
is INT0 – the External Interrupt Request 0.
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.
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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 the following example.
Assembly Code Example
sei
; set Global Interrupt Enable
sleep
; enter sleep, waiting for interrupt
; note: will enter sleep before any pending interrupt(s)
Note:
4.7.1
See “Code Examples” on page 5.
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.
4.8
4.8.1
Register Description
CCP – Configuration Change Protection Register
Bit
7
6
5
4
0x3C
3
2
1
0
CCP[7:0]
CCP
Read/Write
W
W
W
W
W
W
W
R/W
Initial Value
0
0
0
0
0
0
0
0
• Bits 7:0 – CCP[7:0] – Configuration Change Protection
In order to change the contents of a protected I/O register the CCP register must first be written with the correct
signature. After CCP is written the protected I/O registers may be written to during the next four CPU instruction
cycles. All interrupts are ignored during these cycles. After these cycles interrupts are automatically handled again
by the CPU, and any pending interrupts will be executed according to their priority.
When the protected I/O register signature is written, CCP[0] will read as one as long as the protected feature is
enabled, while CCP[7:1] will always read as zero.
Table 4-1 shows the signatures that are in recognised.
Table 4-1.
Signatures Recognised by the Configuration Change Protection Register
Signature
Group
Description
0xD8
IOREG: CLKMSR, CLKPSR, WDTCSR
Protected I/O register
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4.8.2
SPH and SPL — Stack Pointer Register
Bit
4.8.3
15
14
13
12
11
10
9
8
0x3E
SP15
SP14
SP13
SP12
SP11
SP10
SP9
SP8
SPH
0x3D
SP7
SP6
SP5
SP4
SP3
SP2
SP1
SP0
SPL
7
6
5
4
3
2
1
0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
RAMEND
RAMEND
RAMEND
RAMEND
RAMEND
RAMEND
RAMEND
RAMEND
Initial Value
RAMEND
RAMEND
RAMEND
RAMEND
RAMEND
RAMEND
RAMEND
RAMEND
SREG – Status Register
Bit
7
6
5
4
3
2
1
0
0x3F
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 document “AVR Instruction
Set” and “Instruction Set Summary” on page 150.
• 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 document “AVR Instruction Set” and section “Instruction Set Summary” on page 150 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
document “AVR Instruction Set” and section “Instruction Set Summary” on page 150 for detailed information.
• Bit 3 – V: Two’s Complement Overflow Flag
The Two’s Complement Overflow Flag V supports two’s complement arithmetics. See document “AVR Instruction
Set” and section “Instruction Set Summary” on page 150 for detailed information.
• Bit 2 – N: Negative Flag
The Negative Flag N indicates a negative result in an arithmetic or logic operation. See document “AVR Instruction
Set” and section “Instruction Set Summary” on page 150 for detailed information.
• Bit 1 – Z: Zero Flag
The Zero Flag Z indicates a zero result in an arithmetic or logic operation. See document “AVR Instruction Set” and
section “Instruction Set Summary” on page 150 for detailed information.
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• Bit 0 – C: Carry Flag
The Carry Flag C indicates a carry in an arithmetic or logic operation. See document “AVR Instruction Set” and
section “Instruction Set Summary” on page 150 for detailed information.
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5. Memories
This section describes the different memories in the ATtiny4/5/9/10. Devices have two main memory areas, the
program memory space and the data memory space.
5.1
In-System Re-programmable Flash Program Memory
The ATtiny4/5/9/10 contain 512/1024 bytes of 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 256/512 x 16.
The Flash memory has an endurance of at least 10,000 write/erase cycles. The ATtiny4/5/9/10 Program Counter
(PC) is 9 bits wide, thus capable of addressing the 256/512 program memory locations, starting at 0x000. “Memory
Programming” on page 106 contains a detailed description on Flash data serial downloading.
Constant tables can be allocated within the entire address space of program memory. Since program memory can
not be accessed directly, it has been mapped to the data memory. The mapped program memory begins at byte
address 0x4000 in data memory (see Figure 5-1 on page 15). Although programs are executed starting from
address 0x000 in program memory it must be addressed starting from 0x4000 when accessed via the data
memory.
Internal write operations to Flash program memory have been disabled and program memory therefore appears to
firmware as read-only. Flash memory can still be written to externally but internal write operations to the program
memory area will not be succesful.
Timing diagrams of instruction fetch and execution are presented in “Instruction Execution Timing” on page 9.
5.2
Data Memory
Data memory locations include the I/O memory, the internal SRAM memory, the non-volatile memory lock bits, and
the Flash memory. See Figure 5-1 on page 15 for an illustration on how the ATtiny4/5/9/10 memory space is
organized.
The first 64 locations are reserved for I/O memory, while the following 32 data memory locations address the internal data SRAM.
The non-volatile memory lock bits and all the Flash memory sections are mapped to the data memory space.
These locations appear as read-only for device firmware.
The four different addressing modes for data memory are direct, indirect, indirect with pre-decrement, and indirect
with post-increment. In the register file, registers R26 to R31 function as pointer registers for indirect addressing.
The IN and OUT instructions can access all 64 locations of I/O memory. Direct addressing using the LDS and STS
instructions reaches the 128 locations between 0x0040 and 0x00BF.
The indirect addressing reaches the entire data memory space. When using 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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Figure 5-1.
Data Memory Map (Byte Addressing)
I/O SPACE
0x0000 ... 0x003F
SRAM DATA MEMORY
0x0040 ... 0x005F
(reserved)
0x0060 ... 0x3EFF
NVM LOCK BITS
0x3F00 ... 0x3F01
(reserved)
0x3F02 ... 0x3F3F
CONFIGURATION BITS
0x3F40 ... 0x3F41
(reserved)
0x3F42 ... 0x3F7F
CALIBRATION BITS
0x3F80 ... 0x3F81
(reserved)
0x3F82 ... 0x3FBF
DEVICE ID BITS
0x3FC0 ... 0x3FC3
(reserved)
0x3FC4 ... 0x3FFF
FLASH PROGRAM MEMORY
(reserved)
0x4400 ... 0xFFFF
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 5-2.
On-chip Data SRAM Access Cycles
T1
T2
T3
clkCPU
Address
Compute Address
Address valid
Data
Write
Figure 5-2.
WR
Data
Read
5.2.1
0x4000 ... 0x41FF/0x43FF
RD
Memory Access Instruction
Next Instruction
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5.3
I/O Memory
The I/O space definition of the ATtiny4/5/9/10 is shown in “Register Summary” on page 148.
All ATtiny4/5/9/10 I/Os and peripherals are placed in the I/O space. All I/O locations may be accessed using the LD
and ST instructions, enabling data transfer between the 16 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. See document
“AVR Instruction Set” and section “Instruction Set Summary” on page 150 for more details. When using the I/O
specific commands IN and OUT, the I/O addresses 0x00 - 0x3F must be used.
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 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 on registers in the address range 0x00 to 0x1F, only.
The I/O and Peripherals Control Registers are explained in later sections.
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6. Clock System
Figure 6-1 presents the principal clock systems and their distribution in ATtiny4/5/9/10. 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 and power reduction register bits, as described in “Power Management and
Sleep Modes” on page 23. The clock systems is detailed below.
Figure 6-1.
Clock Distribution
ANALOG-TO-DIGITAL
CONVERTER
clk ADC
GENERAL
I/O MODULES
CPU
CORE
clk I/O
NVM
RAM
clk NVM
clk CPU
CLOCK CONTROL UNIT
SOURCE CLOCK
RESET
LOGIC
WATCHDOG
CLOCK
CLOCK
PRESCALER
WATCHDOG
TIMER
CLOCK
SWITCH
EXTERNAL
CLOCK
6.1
WATCHDOG
OSCILLATOR
CALIBRATED
OSCILLATOR
Clock Subsystems
The clock subsystems are detailed in the sections below.
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 System Registers and the SRAM data memory. 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
NVM clock - clkNVM
The NVM clock controls operation of the Non-Volatile Memory Controller. The NVM clock is usually active simultaneously with the CPU clock.
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6.1.4
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.
The ADC is available in ATtiny5/10, only.
6.2
Clock Sources
All synchronous clock signals are derived from the main clock. The device has three alternative sources for the
main clock, as follows:
• Calibrated Internal 8 MHz Oscillator (see page 18)
• External Clock (see page 18)
• Internal 128 kHz Oscillator (see page 19)
See Table 6-3 on page 21 on how to select and change the active clock source.
6.2.1
Calibrated Internal 8 MHz Oscillator
The calibrated internal oscillator provides an approximately 8 MHz clock signal. Though voltage and temperature
dependent, this clock can be very accurately calibrated by the user. See Table 16-2 on page 117, Figure 17-39 on
page 141 and Figure 17-40 on page 141 for more details.
This clock may be selected as the main clock by setting the Clock Main Select bits CLKMS[1:0] in CLKMSR to
0b00. Once enabled, the oscillator will operate with no external components. During reset, hardware loads the calibration byte into the OSCCAL register and thereby automatically calibrates the oscillator. The accuracy of this
calibration is shown as Factory calibration in Table 16-2 on page 117.
When this oscillator is used as the main clock, the watchdog oscillator will still be used for the watchdog timer and
reset time-out. For more information on the pre-programmed calibration value, see section “Calibration Section” on
page 109.
6.2.2
External Clock
To use the device with an external clock source, CLKI should be driven as shown in Figure 6-2. The external clock
is selected as the main clock by setting CLKMS[1:0] bits in CLKMSR to 0b10.
Figure 6-2.
External Clock Drive Configuration
EXTERNAL
CLOCK
SIGNAL
CLKI
GND
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.
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6.2.3
Internal 128 kHz Oscillator
The internal 128 kHz 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 main clock by setting the
CLKMS[1:0] bits in CLKMSR to 0b01.
6.2.4
Switching Clock Source
The main clock source can be switched at run-time using the “CLKMSR – Clock Main Settings Register” on page
21. When switching between any clock sources, the clock system ensures that no glitch occurs in the main clock.
6.2.5
Default Clock Source
The calibrated internal 8 MHz oscillator is always selected as main clock when the device is powered up or has
been reset. The synchronous system clock is the main clock divided by 8, controlled by the System Clock Prescaler. The Clock Prescaler Select Bits can be written later to change the system clock frequency. See “System
Clock Prescaler”.
6.3
System Clock Prescaler
The system clock is derived from the main clock via the System Clock Prescaler. The system clock can be divided
by setting the “CLKPSR – Clock Prescale Register” on page 22. The system clock prescaler can be used to
decrease power consumption at times when requirements for processing power is low or to bring the system clock
within limits of maximum frequency. The prescaler can be used with all main clock source options, and it will affect
the clock frequency of the CPU and all synchronous peripherals.
The System Clock Prescaler can be used to implement run-time changes of the internal clock frequency while still
ensuring stable operation.
6.3.1
Switching Prescaler Setting
When switching between prescaler settings, the system clock prescaler ensures that no glitch occurs in the system
clock and that no intermediate frequency is higher than neither the clock frequency corresponding the previous setting, nor the clock frequency corresponding to the new setting.
The ripple counter that implements the prescaler runs at the frequency of the main 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, two active clock edges are produced. Here, T1 is the previous clock period, and
T2 is the period corresponding to the new prescaler setting.
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6.4
Starting
6.4.1
Starting from Reset
The internal reset is immediately asserted when a reset source goes active. The internal reset is kept asserted until
the reset source is released and the start-up sequence is completed. The start-up sequence includes three steps,
as follows.
1. The first step after the reset source has been released consists of the device counting the reset start-up
time. The purpose of this reset start-up time is to ensure that supply voltage has reached sufficient levels.
The reset start-up time is counted using the internal 128 kHz oscillator. See Table 6-1 for details of reset
start-up time.
Note that the actual supply voltage is not monitored by the start-up logic. The device will count until the
reset start-up time has elapsed even if the device has reached sufficient supply voltage levels earlier.
2. The second step is to count the oscillator start-up time, which ensures that the calibrated internal oscillator
has reached a stable state before it is used by the other parts of the system. The calibrated internal oscillator needs to oscillate for a minimum number of cycles before it can be considered stable. See Table 6-1
for details of the oscillator start-up time.
3. The last step before releasing the internal reset is to load the calibration and the configuration values from
the Non-Volatile Memory to configure the device properly. The configuration time is listed in Table 6-1.
Table 6-1.
Reset
Oscillator
Configuration
64 ms
6 cycles
21 cycles
Notes:
6.4.2
Total start-up time
64 ms + 6 oscillator cycles + 21 system clock cycles (1)
1. After powering up the device or after a reset the system clock is automatically set to calibrated internal 8 MHz oscillator, divided by 8
Starting from Power-Down Mode
When waking up from Power-Down sleep mode, the supply voltage is assumed to be at a sufficient level and only
the oscillator start-up time is counted to ensure the stable operation of the oscillator. The oscillator start-up time is
counted on the selected main clock, and the start-up time depends on the clock selected. See Table 6-2 for details.
Table 6-2.
Notes:
6.4.3
Start-up Times when Using the Internal Calibrated Oscillator
Start-up Time from Power-Down Sleep Mode.
Oscillator start-up time
Total start-up time
6 cycles
6 oscillator cycles (1)
1. The start-up time is measured in main clock oscillator cycles.
Starting from Idle / ADC Noise Reduction / Standby Mode
When waking up from Idle, ADC Noise Reduction or Standby Mode, the oscillator is already running and no oscillator start-up time is introduced.
The ADC is available in ATtiny5/10, only.
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6.5
Register Description
6.5.1
CLKMSR – Clock Main Settings Register
Bit
7
6
5
4
3
2
1
0
0x37
–
–
–
–
–
–
CLKMS1
CLKMS0
Read/Write
R
R
R
R
R
R
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
CLKMSR
• Bit 7:2 – Res: Reserved Bits
These bits are reserved and always read zero.
• Bit 1:0 – CLKMS[1:0]: Clock Main Select Bits
These bits select the main clock source of the system. The bits can be written at run-time to switch the source of
the main clock. The clock system ensures glitch free switching of the main clock source.
The main clock alternatives are shown in Table 6-3.
Table 6-3.
Selection of Main Clock
CLKM1
CLKM0
Main Clock Source
0
0
Calibrated Internal 8 MHzOscillator
0
1
Internal 128 kHz Oscillator (WDT Oscillator)
1
0
External clock
1
1
Reserved
To avoid unintentional switching of main clock source, a protected change sequence must be followed to change
the CLKMS bits, as follows:
1. Write the signature for change enable of protected I/O register to register CCP
2. Within four instruction cycles, write the CLKMS bits with the desired value
6.5.2
OSCCAL – Oscillator Calibration Register
.
Bit
7
6
5
4
3
2
1
0
CAL7
CAL6
CAL5
CAL4
CAL3
CAL2
CAL1
CAL0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
X
X
X
X
X
X
X
X
0x39
OSCCAL
• Bits 7:0 – CAL[7:0]: Oscillator Calibration Value
The oscillator calibration register is used to trim the calibrated internal oscillator and remove process variations
from the oscillator frequency. A pre-programmed calibration value is automatically written to this register during
chip reset, giving the factory calibrated frequency as specified in Table 16-2, “Calibration Accuracy of Internal RC
Oscillator,” on page 117.
The application software can write this register to change the oscillator frequency. The oscillator can be calibrated
to frequencies as specified in Table 16-2, “Calibration Accuracy of Internal RC Oscillator,” on page 117. Calibration
outside the range given is not guaranteed.
The CAL[7:0] bits are used to tune the frequency of the oscillator. A setting of 0x00 gives the lowest frequency, and
a setting of 0xFF gives the highest frequency.
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6.5.3
CLKPSR – Clock Prescale Register
Bit
7
6
5
4
3
2
1
0
0x36
–
–
–
–
CLKPS3
CLKPS2
CLKPS1
CLKPS0
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
1
1
CLKPSR
• Bits 7:4 – Res: Reserved Bits
These bits are reserved and will always read as zero.
• Bits 3:0 – CLKPS[3:0]: 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 at run-time to vary the clock frequency and suit the application requirements. As the prescaler
divides the master clock input to the MCU, the speed of all synchronous peripherals is reduced accordingly. The
division factors are given in Table 6-4.
Table 6-4.
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 (default)
0
1
0
0
16
0
1
0
1
32
0
1
1
0
64
0
1
1
1
128
1
0
0
0
256
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
To avoid unintentional changes of clock frequency, a protected change sequence must be followed to change the
CLKPS bits:
1. Write the signature for change enable of protected I/O register to register CCP
2. Within four instruction cycles, write the desired value to CLKPS bits
At start-up, CLKPS bits are reset to 0b0011 to select the clock division factor of 8. If the selected clock source has
a frequency higher than the maximum allowed the application software must make sure a sufficient division factor
is used. To make sure the write procedure is not interrupted, interrupts must be disabled when changing prescaler
settings.
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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 17 presents the different clock systems and their distribution in ATtiny4/5/9/10. 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 Different Sleep Modes
ADC Noise Reduction
Main Clock
Source Enabled
INT0 and
Pin Change
ADC (1)
Other I/O
Watchdog
Interrupt
VLM Interrupt
X
X
X
X
X
X
X
X
X
Standby
Power-down
Note:
Wake-up Sources
clkADC (1)
Idle
Oscillators
clkIO
clkNVM
Sleep Mode
clkCPU
Active Clock Domains
X
X
X
(2)
X
(2)
X
X
(2)
X
X
X
X
1. The ADC is available in ATtiny5/10, only
2. For INT0, only level interrupt.
To enter any of the four sleep modes, the SE bits in SMCR must be written to logic one and a SLEEP instruction
must be executed. The SM2:0 bits in the SMCR register select which sleep mode (Idle, ADC Noise Reduction,
Standby or Power-down) will be activated by the SLEEP instruction. See Table 7-2 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 the changed level must be held for some time to wake up
the MCU (and for the MCU to enter the interrupt service routine). See “External Interrupts” on page 36 for details.
7.1.1
Idle Mode
When bits SM2:0 are written to 000, the SLEEP instruction makes the MCU enter Idle mode, stopping the CPU but
allowing the analog comparator, timer/counter, watchdog, and the interrupt system to continue operating. This
sleep mode basically halts clkCPU and clkNVM, 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 “ACSR – Analog Comparator Control and Status Register” on page 80. This will
reduce power consumption in idle mode. If the ADC is enabled (ATtiny5/10, only), a conversion starts automatically
when this mode is entered.
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7.1.2
ADC Noise Reduction Mode
When bits SM2:0 are written to 001, 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 clkNVM, while allowing the other clocks to run.
This mode 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.
This mode is available in all devices, although only ATtiny5/10 are equipped with an ADC.
7.1.3
Power-down Mode
When bits SM2:0 are written to 010, the SLEEP instruction makes the MCU enter Power-down mode. In this mode,
the oscillator is stopped, while the external interrupts, and the watchdog continue operating (if enabled). Only a
watchdog 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.
7.1.4
Standby Mode
When bits SM2:0 are written to 100, the SLEEP instruction makes the MCU enter Standby mode. This mode is
identical to Power-down with the exception that the oscillator is kept running. This reduces wake-up time, because
the oscillator is already running and doesn't need to be started up.
7.2
Power Reduction Register
The Power Reduction Register (PRR), see “PRR – Power Reduction Register” on page 26, provides a method to
reduce power consumption by stopping the clock to individual peripherals. When the clock for a peripheral is
stopped then:
• The current state of the peripheral is frozen.
• The associated registers can not be read or written.
• Resources used by the peripheral will remain occupied.
The peripheral should in most cases be disabled before stopping the clock. Clearing the PRR bit wakes up the
peripheral and puts it in the same state as before shutdown.
Peripheral shutdown can be used in Idle mode and Active mode to significantly reduce the overall power consumption. See “Supply Current of I/O Modules” on page 121 for examples. In all other sleep modes, the clock is already
stopped.
7.3
Minimizing Power Consumption
There are several issues to consider when trying to minimize the power consumption in an AVR Core 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.
7.3.1
Analog Comparator
When entering Idle mode, the analog comparator should be disabled if not used. In the power-down mode, the
analog comparator is automatically disabled. See “Analog Comparator” on page 80 for further details.
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7.3.2
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.
See “Analog to Digital Converter” on page 82 for details on ADC operation.
The ADC is available in ATtiny5/10, only.
7.3.3
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 “Watchdog Timer” on page 30 for details on
how to configure the Watchdog Timer.
7.3.4
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 the I/O clock (clkI/O) is 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 44 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 81 for
details.
7.4
Register Description
7.4.1
SMCR – Sleep Mode Control Register
The SMCR Control Register contains control bits for power management.
Bit
7
6
5
4
3
2
1
0
0x3A
–
–
–
–
SM2
SM1
SM0
SE
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
SMCR
• Bits 7:4 – Res: Reserved Bits
These bits are reserved and will always read zero.
• Bits 3:1 – SM2..SM0: Sleep Mode Select Bits 2..0
These bits select between available sleep modes, as shown in Table 7-2.
Table 7-2.
Sleep Mode Select
SM2
SM1
SM0
Sleep Mode
0
0
0
Idle
0
0
1
ADC noise reduction (1)
0
1
0
Power-down
0
1
1
Reserved
1
0
0
Standby
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Table 7-2.
Note:
Sleep Mode Select
SM2
SM1
SM0
Sleep Mode
1
0
1
Reserved
1
1
0
Reserved
1
1
1
Reserved
1. This mode is available in all devices, although only ATtiny5/10 are equipped with an ADC
• Bit 0 – 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.
7.4.2
PRR – Power Reduction Register
Bit
7
6
5
4
3
2
1
0
0x35
–
–
–
–
–
–
PRADC
PRTIM0
Read/Write
R
R
R
R
R
R
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
PRR
• Bits 7:2 – Res: Reserved Bits
These bits are reserved and will always read zero.
• Bit 1 – PRADC: Power Reduction ADC
Writing a logic one to this bit shuts down the ADC. The ADC must be disabled before shut down. The analog comparator cannot use the ADC input MUX when the ADC is shut down.
The ADC is available in ATtiny5/10, only.
• Bit 0 – PRTIM0: Power Reduction Timer/Counter0
Writing a logic one to this bit shuts down the Timer/Counter0 module. When the Timer/Counter0 is enabled, operation will continue like before the shutdown.
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8. System Control and Reset
8.1
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 shows the reset logic. Electrical parameters of
the reset circuitry are defined in section “System and Reset Characteristics” on page 118.
Figure 8-1.
Reset Logic
DATA BUS
WDRF
PORF
Power-on Reset
Circuit
EXTRF
Reset Flag Register
(RSTFLR)
VLM
Pull-up Resistor
SPIKE
FILTER
Watchdog
Oscillator
Clock
Generator
CK
Delay Counters
TIMEOUT
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 start up sequence is described in “Starting from
Reset” on page 20.
8.2
Reset Sources
The ATtiny4/5/9/10 have three sources of reset:
• Power-on Reset. The MCU is reset when the supply voltage is below the Power-on Reset threshold (VPOT)
• External Reset. The MCU is reset when a low level is present on the RESET pin for longer than the minimum
pulse length
• Watchdog Reset. The MCU is reset when the Watchdog Timer period expires and the Watchdog is enabled
8.2.1
Power-on Reset
A Power-on Reset (POR) pulse is generated by an on-chip detection circuit. The detection level is defined in section “System and Reset Characteristics” on page 118. 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.
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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.
MCU Start-up, RESET Tied to VCC
V CC
V POT
RESET
V RST
TIME-OUT
t TOUT
INTERNAL
RESET
Figure 8-3.
MCU Start-up, RESET Extended Externally
V CC
V POT
> t TOUT
RESET
TIME-OUT
V RST
t TOUT
INTERNAL
RESET
8.2.2
VCC Level Monitoring
ATtiny4/5/9/10 have a VCC Level Monitoring (VLM) circuit that compares the voltage level at the VCC pin against
fixed trigger levels. The trigger levels are set with VLM2:0 bits, see “VLMCSR – VCC Level Monitoring Control and
Status register” on page 33.
The VLM circuit provides a status flag, VLMF, that indicates if voltage on the VCC pin is below the selected trigger
level. The flag can be read from VLMCSR, but it is also possible to have an interrupt generated when the VLMF
status flag is set. This interrupt is enabled by the VLMIE bit in the VLMCSR register. The flag can be cleared by
changing the trigger level or by writing it to zero. The flag is automatically cleared when the voltage at VCC rises
back above the selected trigger level.
The VLM can also be used to improve reset characteristics at falling supply. Without VLM, the Power-On Reset
(POR) does not activate before supply voltage has dropped to a level where the MCU is not necessarily functional
any more. With VLM, it is possible to generate a reset earlier.
When active, the VLM circuit consumes some power, as illustrated in Figure 17-48 on page 145. To save power
the VLM circuit can be turned off completely, or it can be switched on and off at regular intervals. However, detection takes some time and it is therefore recommended to leave the circuitry on long enough for signals to settle.
See “VCC Level Monitor” on page 118.
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When VLM is active and voltage at VCC is above the selected trigger level operation will be as normal and the VLM
can be shut down for a short period of time. If voltage at VCC drops below the selected threshold the VLM will either
flag an interrupt or generate a reset, depending on the configuration.
When the VLM has been configured to generate a reset at low supply voltage it will keep the device in reset as long
as VCC is below the reset level. See Table 8-4 on page 34 for reset level details. If supply voltage rises above the
reset level the condition is removed and the MCU will come out of reset, and initiate the power-up start-up
sequence.
If supply voltage drops enough to trigger the POR then PORF is set after supply voltage has been restored.
8.2.3
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 section “System and Reset Characteristics” on page 118) 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. External reset is ignored during Power-on start-up count. After Power-on reset the internal reset is
extended only if RESET pin is low when the initial Power-on delay count is complete. See Figure 8-2 and Figure 83 on page 28.
Figure 8-4.
External Reset During Operation
CC
8.2.4
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. See page 30 for details on operation of the
Watchdog Timer and Table 16-4 on page 118 for details on reset time-out.
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Figure 8-5.
Watchdog Reset During Operation
CC
CK
Watchdog Timer
The Watchdog Timer is clocked from an on-chip oscillator, which runs at 128 kHz. See Figure 8-6. By controlling
the Watchdog Timer prescaler, the Watchdog Reset interval can be adjusted as shown in Table 8-2 on page 32.
The WDR – Watchdog Reset – instruction resets the Watchdog Timer. The Watchdog Timer is also reset when it is
disabled and when a device reset occurs. Ten different clock cycle periods can be selected to determine the reset
period. If the reset period expires without another Watchdog Reset, the ATtiny4/5/9/10 resets and executes from
the Reset Vector. For timing details on the Watchdog Reset, refer to Table 8-3 on page 33.
Watchdog Timer
WDP0
WDP1
WDP2
WDP3
OSC/512K
OSC/1024K
OSC/256K
OSC/64K
OSC/128K
OSC/8K
OSC/4K
WATCHDOG
RESET
OSC/32K
WATCHDOG
PRESCALER
128 kHz
OSCILLATOR
OSC/16K
Figure 8-6.
OSC/2K
8.3
MUX
WDE
MCU RESET
The Wathdog Timer can also be configured to generate an interrupt instead of a reset. This can be very helpful
when using the Watchdog to wake-up from Power-down.
To prevent unintentional disabling of the Watchdog or unintentional change of time-out period, two different safety
levels are selected by the fuse WDTON as shown in Table 8-1 on page 31. See “Procedure for Changing the
Watchdog Timer Configuration” on page 31 for details.
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Table 8-1.
WDT Configuration as a Function of the Fuse Settings of WDTON
Safety
Level
WDTON
WDT
Initial State
How to
Disable the WDT
How to
Change Time-out
Unprogrammed
1
Disabled
Protected change
sequence
No limitations
Programmed
2
Enabled
Always enabled
Protected change
sequence
8.3.1
Procedure for Changing the Watchdog Timer Configuration
The sequence for changing configuration differs between the two safety levels, as follows:
8.3.1.1
Safety Level 1
In this mode, the Watchdog Timer is initially disabled, but can be enabled by writing the WDE bit to one without any
restriction. A special sequence is needed when disabling an enabled Watchdog Timer. To disable an enabled
Watchdog Timer, the following procedure must be followed:
1. Write the signature for change enable of protected I/O registers to register CCP
2. Within four instruction cycles, in the same operation, write WDE and WDP bits
8.3.1.2
Safety Level 2
In this mode, the Watchdog Timer is always enabled, and the WDE bit will always read as one. A protected change
is needed when changing the Watchdog Time-out period. To change the Watchdog Time-out, the following procedure must be followed:
1. Write the signature for change enable of protected I/O registers to register CCP
2. Within four instruction cycles, write the WDP bit. The value written to WDE is irrelevant
8.3.2
Code Examples
The following code example shows how to turn off the WDT. The example assumes that interrupts are controlled
(e.g., by disabling interrupts globally) so that no interrupts will occur during execution of these functions.
Assembly Code Example
WDT_off:
wdr
; Clear WDRF in RSTFLR
in
andi
out
r16, RSTFLR
r16, ~(1<<WDRF)
RSTFLR, r16
; Write signature for change enable of protected I/O register
ldi r16, 0xD8
out CCP, r16
; Within four instruction cycles, turn off WDT
ldi r16, (0<<WDE)
out WDTCSR, r16
ret
Note:
See “Code Examples” on page 5.
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8.4
8.4.1
Register Description
WDTCSR – Watchdog Timer Control and Status Register
Bit
7
6
5
4
3
2
1
0
WDIF
WDIE
WDP3
–
WDE
WDP2
WDP1
WDP0
Read/Write
R/W
R/W
R/W
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
X
0
0
0
0x31
WDTCSR
• Bit 7 – WDIF: 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.
WDIF is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, WDIF is
cleared by writing a logic one to the flag. When the WDIE is set, the Watchdog Time-out Interrupt is requested.
• Bit 6 – WDIE: Watchdog Timer Interrupt Enable
When this bit is written to one, the Watchdog interrupt request is enabled. If WDE is cleared in combination with
this setting, the Watchdog Timer is in Interrupt Mode, and the corresponding interrupt is requested 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 WDIF. Executing the corresponding interrupt vector will clear WDIE and WDIF automatically by hardware (the Watchdog goes to System Reset Mode). This is useful for keeping the Watchdog Timer security while
using the interrupt. To stay in Interrupt and System Reset Mode, WDIE 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 8-2.
WDTON
Note:
(1)
Watchdog Timer Configuration
WDE
WDIE
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
1. WDTON configuration bit set to “0“ means programmed and “1“ means unprogrammed.
• Bit 4 – Res: Reserved Bit
This bit is reserved and will always read zero.
• Bit 3 – WDE: Watchdog System Reset Enable
WDE is overridden by WDRF in RSTFLR. 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.
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• Bits 5, 2:0 – WDP3..0: Watchdog Timer Prescaler 3, 2, 1 and 0
The WDP3..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 8-3 on page 33.
Table 8-3.
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
1
0
1
0
1
0
1
1
1
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
Reserved
8.4.2
VLMCSR – VCC Level Monitoring Control and Status register
Bit
7
6
5
4
3
2
1
0
VLMF
VLMIE
–
–
–
VLM2
VLM1
VLM0
Read/Write
R
R/W
R
R
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
0x34
VLMCSR
• Bit 7 – VLMF: VLM Flag
This bit is set by the VLM circuit to indicate that a voltage level condition has been triggered (see Table 8-4). The
bit is cleared when the trigger level selection is set to “Disabled”, or when voltage at VCC rises above the selected
trigger level.
• Bit 6 – VLMIE: VLM Interrupt Enable
When this bit is set the VLM interrupt is enabled. A VLM interrupt is generated every time the VLMF flag is set.
• Bits 5:3 – Res: Reserved Bits
These bits are reserved. For ensuring compatibility with future devices, these bits must be written to zero, when the
register is written.
• Bits 2:0 – VLM2:0: Trigger Level of Voltage Level Monitor
These bits set the trigger level for the voltage level monitor, as described in Table 8-4 below.
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Table 8-4.
Setting the Trigger Level of Voltage Level Monitor.
VLM2:0
Label
Description
000
VLM0
Voltage Level Monitor disabled
001
VLM1L
010
VLM1H
Triggering generates a regular Power-On Reset (POR).
The VLM flag is not set
011
VLM2
100
VLM3
Triggering sets the VLM Flag (VLMF) and generates a VLM
interrupt, if enabled
101
110
Not allowed
111
For VLM voltage levels, see Table 16-6 on page 118.
8.4.3
RSTFLR – Reset Flag Register
The Reset Flag Register provides information on which reset source caused an MCU Reset.
Bit
7
6
5
4
3
2
1
0
0x3B
–
–
–
–
WDRF
–
EXTRF
PORF
Read/Write
R
R
R
R
R/W
R
R/W
R/W
Initial Value
0
0
0
0
X
0
X
X
RSTFLR
• Bits 7:4, 2– Res: Reserved Bits
These bits are reserved bits in ATtiny4/5/9/10 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 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.
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9. Interrupts
This section describes the specifics of the interrupt handling in ATtiny4/5/9/10. For a general explanation of the
AVR interrupt handling, see “Reset and Interrupt Handling” on page 10.
9.1
Interrupt Vectors
Interrupt vectors of ATtiny4/5/9/10 are described in Table 9-1 below.
Table 9-1.
Reset and Interrupt Vectors
Vector No.
Program Address
1
Note:
Label
Interrupt Source
0x0000
RESET
External Pin, Power-on Reset,
VLM Reset, Watchdog Reset
2
0x0001
INT0
External Interrupt Request 0
3
0x0002
PCINT0
Pin Change Interrupt Request 0
4
0x0003
TIM0_CAPT
Timer/Counter0 Input Capture
5
0x0004
TIM0_OVF
Timer/Counter0 Overflow
6
0x0005
TIM0_COMPA
Timer/Counter0 Compare Match A
7
0x0006
TIM0_COMPB
Timer/Counter0 Compare Match B
8
0x0007
ANA_COMP
Analog Comparator
9
0x0008
WDT
Watchdog Time-out
10
0x0009
VLM
VCC Voltage Level Monitor
11
0x000A
ADC
ADC Conversion Complete (1)
1. The ADC is available in ATtiny5/10, only.
In case the program never enables an interrupt source, the Interrupt Vectors will not be used and, consequently,
regular program code can be placed at these locations.
The most typical and general setup for interrupt vector addresses in ATtiny4/5/9/10 is shown in the program example below.
Address Labels Code
Comments
0x0000
rjmp
RESET
; Reset Handler
0x0001
rjmp
INT0
; IRQ0 Handler
0x0002
rjmp
PCINT0
; PCINT0 Handler
0x0003
rjmp
TIM0_CAPT
; Timer0 Capture Handler
0x0004
rjmp
TIM0_OVF
; Timer0 Overflow Handler
0x0005
rjmp
TIM0_COMPA
; Timer0 Compare A Handler
0x0006
rjmp
TIM0_COMPB
; Timer0 Compare B Handler
0x0007
rjmp
ANA_COMP
; Analog Comparator Handler
0x0008
rjmp
WDT
; Watchdog Interrupt Handler
0x0009
rjmp
VLM
; Voltage Level Monitor Handler
0x000A
rjmp
ADC
; ADC Conversion Handler
<continues>
<continued>
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9.2
0x000B
RESET: ldi
0x000C
out
SPH,r16
r16, high(RAMEND); Main program start
0x000D
ldi
r16, low(RAMEND) ; to top of RAM
0x000E
out
SPL,r16
0x000F
sei
0x0010
<instr>
...
...
; Set Stack Pointer
; Enable interrupts
External Interrupts
External Interrupts are triggered by the INT0 pin or any of the PCINT3..0 pins. Observe that, if enabled, the interrupts will trigger even if the INT0 or PCINT3..0 pins are configured as outputs. This feature provides a way of
generating a software interrupt. Pin change 0 interrupts PCI0 will trigger if any enabled PCINT3..0 pin toggles. The
PCMSK Register controls which pins contribute to the pin change interrupts. Pin change interrupts on PCINT3..0
are detected asynchronously, which means that these interrupts can be used for waking the part also from sleep
modes other than Idle mode.
The INT0 interrupt can be triggered by a falling or rising edge or a low level. This is set up as shown in “EICRA –
External Interrupt Control Register A” on page 37. When the INT0 interrupt is enabled and 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, as described in “Clock System” on page 17.
9.2.1
Low Level Interrupt
A low level interrupt on INT0 is detected asynchronously. This means that the interrupt source can be used for
waking the part also from sleep modes other than Idle (the I/O clock is halted in all sleep modes except Idle).
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 as
described in “Clock System” on page 17.
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
A timing example of a pin change interrupt is shown in Figure 9-1.
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Figure 9-1.
Timing of pin change interrupts
pin_lat
PCINT(0)
D
pcint_in_(0)
Q
clk
0
pcint_syn
pcint_setflag
PCIF
pin_sync
LE
x
PCINT(0) in PCMSK(x)
clk
clk
PCINT(0)
pin_lat
pin_sync
pcint_in_(0)
pcint_syn
pcint_setflag
PCIF
9.3
Register Description
9.3.1
EICRA – External Interrupt Control Register A
The External Interrupt Control Register A contains control bits for interrupt sense control.
Bit
7
6
5
4
3
2
1
0
0x15
–
–
–
–
–
–
ISC01
ISC00
Read/Write
R
R
R
R
R
R
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
EICRA
• Bits 7:2 – Res: Reserved Bits
These bits are reserved and will always read zero.
• 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. 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
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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.
EIMSK – External Interrupt Mask Register
Bit
7
6
5
4
3
2
1
0
0x13
–
–
–
–
–
–
–
INTO
Read/Write
R
R
R
R
R
R
R
R/W
Initial Value
0
0
0
0
0
0
0
0
EIMSK
• Bits 7:1 – Res: Reserved Bits
These bits are reserved and will always read zero.
• Bit 0 – 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 Control bits (ISC01 and ISC00) in the External Interrupt Control Register A (EICRA)
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.
9.3.3
EIFR – External Interrupt Flag Register
Bit
7
6
5
4
3
2
1
0
0x14
–
–
–
–
–
–
–
INTF0
Read/Write
R
R
R
R
R
R
R
R/W
Initial Value
0
0
0
0
0
0
0
0
EIFR
• Bits 7:1 – Res: Reserved Bits
These bits are reserved and will always read zero.
• Bit 0 – 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 EIMSK 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 constantly zero when INT0 is configured as a level interrupt.
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9.3.4
PCICR – Pin Change Interrupt Control Register
Bit
7
6
5
4
3
2
1
0
0x12
–
–
–
–
–
–
–
PCIE0
Read/Write
R
R
R
R
R
R
R
R/W
Initial Value
0
0
0
0
0
0
0
0
PCICR
• Bits 7:1 – Res: Reserved Bits
These bits are reserved and will always read zero.
• Bit 0 – PCIE0: Pin Change Interrupt Enable 0
When the PCIE0 bit is set (one) and the I-bit in the Status Register (SREG) is set (one), pin change interrupt 0 is
enabled. Any change on any enabled PCINT3..0 pin will cause an interrupt. The corresponding interrupt of Pin
Change Interrupt Request is executed from the PCI0 Interrupt Vector. PCINT3..0 pins are enabled individually by
the PCMSK Register.
9.3.5
PCIFR – Pin Change Interrupt Flag Register
Bit
7
6
5
4
3
2
1
0
0x11
–
–
–
–
–
–
–
PCIF0
Read/Write
R
R
R
R
R
R
R
R/W
Initial Value
0
0
0
0
0
0
0
0
PCIFR
• Bits 7:1 – Res: Reserved Bits
These bits are reserved and will always read zero.
• Bit 0 – PCIF0: Pin Change Interrupt Flag 0
When a logic change on any PCINT3..0 pin triggers an interrupt request, PCIF0 becomes set (one). If the I-bit in
SREG and the PCIE0 bit in PCICR 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.
9.3.6
PCMSK – Pin Change Mask Register
Bit
7
6
5
4
3
2
1
0
0x10
–
–
–
–
PCINT3
PCINT2
PCINT1
PCINT0
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
PCMSK
• Bits 7:4 – Res: Reserved Bits
These bits are reserved and will always read zero.
• Bits 3:0 – PCINT3..0: Pin Change Enable Mask 3..0
Each PCINT3..0 bit selects whether pin change interrupt is enabled on the corresponding I/O pin. If PCINT3..0 is
set and the PCIE0 bit in PCICR is set, pin change interrupt is enabled on the corresponding I/O pin. If PCINT3..0 is
cleared, pin change interrupt on the corresponding I/O pin is disabled.
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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. 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 on page 40. See “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 50.
Four I/O memory address locations are allocated for each port, one each for the Data Register – PORTx, Data
Direction Register – DDRx, Pull-up Enable Register – PUEx, and the Port Input Pins – PINx. The Port Input Pins
I/O location is read only, while the Data Register, the Data Direction Register, and the Pull-up Enable 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.
Using the I/O port as General Digital I/O is described in “Ports as General Digital I/O” on page 41. 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 45. Refer to the individual module sections
for a full description of the alternate functions.
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.
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10.2
Ports as General Digital I/O
The ports are bi-directional I/O ports with optional internal pull-ups. Figure 10-2 shows a functional description of
one I/O-port pin, here generically called Pxn.
Figure 10-2. General Digital I/O(1)
REx
Q
D
PUExn
Q CLR
RESET
Q
WEx
D
DDxn
Q CLR
WDx
RESET
DATA BUS
RDx
1
Q
Pxn
D
0
PORTxn
Q CLR
RESET
WRx
SLEEP
WPx
RRx
SYNCHRONIZER
D
Q
L
Q
D
RPx
Q
PINxn
Q
clk I/O
SLEEP:
clk I/O :
Note:
10.2.1
SLEEP CONTROL
I/O CLOCK
WEx:
REx:
WDx:
RDx:
WRx:
RRx:
RPx:
WPx:
WRITE PUEx
READ PUEx
WRITE DDRx
READ DDRx
WRITE PORTx
READ PORTx REGISTER
READ PORTx PIN
WRITE PINx REGISTER
1. WEx, WRx, WPx, WDx, REx, RRx, RPx, and RDx are common to all pins within the same port. clkI/O, and SLEEP
are common to all ports.
Configuring the Pin
Each port pin consists of four register bits: DDxn, PORTxn, PUExn, and PINxn. As shown in “Register Description”
on page 50, the DDxn bits are accessed at the DDRx I/O address, the PORTxn bits at the PORTx I/O address, the
PUExn bits at the PUEx 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.
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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).
The pull-up resistor is activated, if the PUExn is written logic one. To switch the pull-up resistor off, PUExn has to
be written logic zero.
Table 10-1 summarizes the control signals for the pin value.
Table 10-1.
Port Pin Configurations
DDxn
PORTxn
PUExn
I/O
Pull-up
Comment
0
X
0
Input
No
Tri-state (hi-Z)
0
X
1
Input
Yes
Sources current if pulled low externally
1
0
0
Output
No
Output low (sink)
1
0
1
Output
Yes
NOT RECOMMENDED.
Output low (sink) and internal pull-up active.
Sources current through the internal pull-up
resistor and consumes power constantly
1
1
0
Output
No
Output high (source)
1
1
1
Output
Yes
Output high (source) and internal pull-up active
Port pins are tri-stated when a reset condition becomes active, even when no clocks are running.
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
Break-Before-Make Switching
In Break-Before-Make mode, switching the DDRxn bit from input to output introduces an immediate tri-state period
lasting one system clock cycle, as indicated in Figure 10-3. For example, if the system clock is 4 MHz and the
DDRxn is written to make an output, an immediate tri-state period of 250 ns is introduced before the value of
PORTxn is seen on the port pin.
To avoid glitches it is recommended that the maximum DDRxn toggle frequency is two system clock cycles. The
Break-Before-Make mode applies to the entire port and it is activated by the BBMx bit. For more details, see
“PORTCR – Port Control Register” on page 50.
When switching the DDRxn bit from output to input no immediate tri-state period is introduced.
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Figure 10-3. Switching Between Input and Output in Break-Before-Make-Mode
SYSTEM CLK
r16
0x02
r17
0x01
INSTRUCTIONS
out DDRx, r16
nop
PORTx
DDRx
0x55
0x02
0x01
Px0
Px1
out DDRx, r17
0x01
tri-state
tri-state
tri-state
intermediate tri-state cycle
10.2.4
intermediate tri-state cycle
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 41, 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 10-4 shows a timing diagram of the synchronization when reading an externally applied pin
value. The maximum and minimum propagation delays are denoted tpd,max and tpd,min respectively.
Figure 10-4. 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 10-5
on page 44. 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.
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Figure 10-5. 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
10.2.5
Digital Input Enable and Sleep Modes
As shown in Figure 10-2 on page 41, the digital input signal can be clamped to ground at the input of the schmitttrigger. The signal denoted SLEEP in the figure, is set by the MCU Sleep Controller in Power-down and Standby
modes 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 45.
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 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 pulldown. 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.
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10.2.7
Program Example
The following code example shows how to set port B pin 0 high, pin 1 low, and define the port pins from 2 to 3 as
input with a pull-up assigned to port pin 2. 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
...
; Define pull-ups and set outputs high
; Define directions for port pins
ldi
r16,(1<<PUEB2)
ldi
r17,(1<<PB0)
ldi
r18,(1<<DDB1)|(1<<DDB0)
out
PUEB,r16
out
PORTB,r17
out
DDRB,r18
; Insert nop for synchronization
nop
; Read port pins
in
r16,PINB
...
Note:
10.3
See “Code Examples” on page 5.
Alternate Port Functions
Most port pins have alternate functions in addition to being general digital I/Os. In Figure 10-6 below is shown how
the port pin control signals from the simplified Figure 10-2 on page 41 can be overridden by alternate functions.
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Figure 10-6. Alternate Port Functions(1)
PUOExn
REx
PUOVxn
1
Q
0
D
PUExn
Q CLR
DDOExn
RESET
WEx
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
D
Q
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
WEx:
REx:
WDx:
RDx:
RRx:
WRx:
RPx:
WPx:
clk I/O :
DIxn:
AIOxn:
WRITE PUEx
READ PUEx
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
1. WEx, WRx, WPx, WDx, REx, RRx, RPx, and RDx are common to all pins within the same port. clkI/O, and SLEEP
are common to all ports. All other signals are unique for each pin.
The illustration in the figure above serves as a generic description applicable to all port pins in the AVR microcontroller family. Some overriding signals may not be present in all port pins.
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Table 10-2 on page 47 summarizes the function of the overriding signals. The pin and port indexes from Figure 106 on page 46 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
PUExn = 0b1.
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 PUExn Register bit.
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 bidirectionally.
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.
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10.3.1
Alternate Functions of Port B
The Port B pins with alternate function are shown in Table 10-3 on page 48.
Table 10-3.
Port B Pins Alternate Functions
Port Pin
Alternate Function
PB0
ADC0: ADC Input Channel 0
AIN0:
Analog Comparator, Positive Input
OC0A: Timer/Counter0 Compare Match A Output
PCINT0: Pin Change Interrupt 0, Source 0
TPIDATA:Serial Programming Data
PB1
ADC1: ADC Input Channel 1
AIN1:
Analog Comparator, Negative Input
CLKI:
External Clock
ICP0:
Timer/Counter0 Input Capture Input
OC0B: Timer/Counter0 Compare Match B Output
PCINT1:Pin Change Interrupt 0, Source 1
TPICLK: Serial Programming Clock
PB2
ADC2: ADC Input Channel 2
CLKO: System Clock Output
INT0:
External Interrupt 0 Source
PCINT2: Pin Change Interrupt 0, Source 2
T0:
Timer/Counter0 Clock Source
PB3
ADC3: ADC Input Channel 3
PCINT3: Pin Change Interrupt 0, Source 3
RESET: Reset Pin
• Port B, Bit 0 – ADC0/AIN0/OC0A/PCINT0/TPIDATA
• ADC0: Analog to Digital Converter, Channel 0 (ATtiny5/10, only)
• AIN0: Analog Comparator Positive Input. Configure the port pin as input with the internal pull-up switched off to
avoid the digital port function from interfering with the function of the Analog Comparator.
• OC0A, Output Compare Match output: The PB0 pin can serve as an external output for the Timer/Counter0
Compare Match A. The pin has to be configured as an output (DDB0 set (one)) to serve this function. This is
also the output pin for the PWM mode timer function.
• PCINT0: Pin Change Interrupt source 0. The PB0 pin can serve as an external interrupt source for pin change
interrupt 0.
• TPIDATA: Serial Programming Data.
• Port B, Bit 1 – ADC1/AIN1/CLKI/ICP0/OC0B/PCINT1/TPICLK
• ADC1: Analog to Digital Converter, Channel 1 (ATtiny5/10, only)
• AIN1: Analog Comparator Negative Input. Configure the port pin as input with the internal pull-up switched off to
avoid the digital port function from interfering with the function of the Analog Comparator.
• CLKI: External Clock.
• ICP0: Input Capture Pin. The PB1 pin can act as an Input Capture pin for Timer/Counter0.
• OC0B: Output Compare Match output: The PB1 pin can serve as an external output for the Timer/Counter0
Compare Match B. The PB1 pin has to be configured as an output (DDB1 set (one)) to serve this function. The
OC0B pin is also the output pin for the PWM mode timer function.
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• PCINT1: Pin Change Interrupt source 1. The PB1 pin can serve as an external interrupt source for pin change
interrupt 0.
• TPICLK: Serial Programming Clock.
• Port B, Bit 2 – ADC2/CLKO/INT0/PCINT2/T0
• ADC2: Analog to Digital Converter, Channel 2 (ATtiny5/10, only)
• CLKO: System Clock Output. The system clock can be output on pin PB2. The system clock will be output if
CKOUT bit is programmed, regardless of the PORTB2 and DDB2 settings.
• INT0: External Interrupt Request 0
• PCINT2: Pin Change Interrupt source 2. The PB2 pin can serve as an external interrupt source for pin change
interrupt 0.
• T0: Timer/Counter0 counter source.
• Port B, Bit 3 – ADC3/PCINT3/RESET
• ADC3: Analog to Digital Converter, Channel 3 (ATtiny5/10, only)
• PCINT3: Pin Change Interrupt source 3. The PB3 pin can serve as an external interrupt source for pin change
interrupt 0.
• RESET:
Table 10-4 and Table 10-5 on page 50 relate the alternate functions of Port B to the overriding signals shown in
Figure 10-6 on page 46.
Table 10-4.
Signal
Name
Overriding Signals for Alternate Functions in PB3..PB2
PB3/ADC3/RESET/PCINT3
PUOE
RSTDISBL
PUOV
1
(1)
PB2/ADC2/INT0/T0/CLKO/PCINT2
CKOUT(2)
0
(1)
CKOUT(2)
DDOE
RSTDISBL
DDOV
0
1
PVOE
0
CKOUT(2)
PVOV
0
(system clock)
PTOE
0
0
DIEOE
RSTDISBL(1) + (PCINT3 • PCIE0) +
ADC3D
(PCINT2 • PCIE0) + ADC2D + INT0
DIEOV
RSTDISBL • PCINT3 • PCIE0
(PCINT2 • PCIE0) + INT0
DI
PCINT3 Input
INT0/T0/PCINT2 Input
AIO
ADC3 Input
ADC2 Input
Notes:
1. RSTDISBL is 1 when the configuration bit is “0” (Programmed).
2. CKOUT is 1 when the configuration bit is “0” (Programmed).
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Table 10-5.
Signal
Name
PB1/ADC1/AIN1/OC0B/CLKI/ICP0/PCINT1
PUOE
EXT_CLOCK
0
PUOV
0
0
DDOE
EXT_CLOCK(1)
0
DDOV
0
0
EXT_CLOCK
(1)
+ OC0B Enable
OC0A Enable
PVOV
EXT_CLOCK
(1)
• OC0B
OC0A
PTOE
0
0
(1)
+ (PCINT1 • PCIE0) +
DIEOE
EXT_CLOCK
ADC1D
DIEOV
(EXT_CLOCK(1) • PWR_DOWN) +
(EXT_CLOCK(1) • PCINT1 • PCIE0)
PCINT0 • PCIE0
DI
CLOCK/ICP0/PCINT1 Input
PCINT0 Input
AIO
ADC1/Analog Comparator Negative Input
ADC0/Analog Comparator Positive Input
Notes:
10.4.1
PB0/ADC0/AIN0/OC0A/PCINT0
(1)
PVOE
10.4
Overriding Signals for Alternate Functions in PB1..PB0
(PCINT0 • PCIE0) + ADC0D
1. EXT_CLOCK is 1 when external clock is selected as main clock.
Register Description
PORTCR – Port Control Register
Bit
7
6
5
4
3
2
1
0x03
–
–
–
–
–
–
BBMB
0
–
Read/Write
R
R
R
R
R
R
R/W
R
Initial Value
0
0
0
0
0
0
0
0
PORTCR
• Bits 7:2, 0 – Reserved
These bits are reserved and will always read zero.
• Bit 1 – BBMB: Break-Before-Make Mode Enable
When this bit is set the Break-Before-Make mode is activated for the entire Port B. The intermediate tri-state cycle
is then inserted when writing DDRxn to make an output. For further information, see “Break-Before-Make Switching” on page 42.
10.4.2
PUEB – Port B Pull-up Enable Control Register
Bit
7
6
5
4
3
2
1
0
0x03
–
–
–
–
PUEB3
PUEB2
PUEB1
PUEB0
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
PUEB
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10.4.3
10.4.4
10.4.5
PORTB – Port B Data Register
Bit
7
6
5
4
3
2
1
0
0x02
–
–
–
–
PORTB3
PORTB2
PORTB1
PORTB0
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
PORTB
DDRB – Port B Data Direction Register
Bit
7
6
5
4
3
2
1
0
0x01
–
–
–
–
DDB3
DDB2
DDB1
DDB0
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
DDRB
PINB – Port B Input Pins
Bit
7
6
5
4
3
2
1
0
0x00
–
–
–
–
PINB3
PINB2
PINB1
PINB0
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
N/A
N/A
N/A
N/A
PINB
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11. 16-bit Timer/Counter0
Features
•
•
•
•
•
•
•
•
•
•
•
11.2
True 16-bit Design, Including 16-bit PWM
Two Independent Output Compare Units
Double Buffered Output Compare Registers
One Input Capture Unit
Input Capture Noise Canceler
Clear Timer on Compare Match (Auto Reload)
Glitch-free, Phase Correct Pulse Width Modulator (PWM)
Variable PWM Period
Frequency Generator
External Event Counter
Four independent interrupt Sources (TOV0, OCF0A, OCF0B, and ICF0)
Overview
The 16-bit Timer/Counter unit allows accurate program execution timing (event management), wave generation,
and signal timing measurement.
Figure 11-1. 16-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
OCRnA
DATA BUS
11.1
OCnB
(Int.Req.)
Fixed
TOP
Values
Waveform
Generation
=
OCRnB
OCnB
( From Analog
Comparator Ouput )
ICFn (Int.Req.)
Edge
Detector
ICRn
Noise
Canceler
ICPn
TCCRnA
TCCRnB
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A simplified block diagram of the 16-bit Timer/Counter is shown in Figure 11-1 on page 52. For actual placement of
I/O pins, refer to “Pinout of ATtiny4/5/9/10” 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 72.
Most register and bit references in this section are written in general form. A lower case “n” replaces the
Timer/Counter number, and a lower case “x” replaces the Output Compare unit channel. 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.
11.2.1
Registers
The Timer/Counter (TCNT0), Output Compare Registers (OCR0A/B), and Input Capture Register (ICR0) are all
16-bit registers. Special procedures must be followed when accessing the 16-bit registers. These procedures are
described in the section “Accessing 16-bit Registers” on page 70. The Timer/Counter Control Registers
(TCCR0A/B) are 8-bit registers and have no CPU access restrictions. Interrupt requests (abbreviated to Int.Req. in
the figure) signals are all visible in the Timer Interrupt Flag Register (TIFR). All interrupts are individually masked
with the Timer Interrupt Mask Register (TIMSK). TIFR and TIMSK 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/B) are compared with the Timer/Counter value at all time.
The result of the compare can be used by the Waveform Generator to generate a PWM or variable frequency output on the Output Compare pin (OC0A/B). See “Output Compare Units” on page 58. The compare match event will
also set the Compare Match Flag (OCF0A/B) which can be used to generate an Output Compare interrupt request.
The Input Capture Register can capture the Timer/Counter value at a given external (edge triggered) event on
either the Input Capture pin (ICP0) or on the Analog Comparator pins (See “Analog Comparator” on page 80). The
Input Capture unit includes a digital filtering unit (Noise Canceler) for reducing the chance of capturing noise
spikes.
The TOP value, or maximum Timer/Counter value, can in some modes of operation be defined by either the
OCR0A Register, the ICR0 Register, or by a set of fixed values. When using OCR0A as TOP value in a PWM
mode, the OCR0A Register can not be used for generating a PWM output. However, the TOP value will in this
case be double buffered allowing the TOP value to be changed in run time. If a fixed TOP value is required, the
ICR0 Register can be used as an alternative, freeing the OCR0A to be used as PWM output.
11.2.2
Definitions
The following definitions are used extensively throughout the section:
Table 11-1.
Definitions
Constant
Description
BOTTOM
The counter reaches 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 depends on the mode of operation
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11.3
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 B (TCCR0B). For details on clock sources and prescaler, see section “Prescaler”.
11.3.1
Prescaler
The Timer/Counter can be clocked directly by the system clock (by setting the CS2:0 = 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.
See Figure 11-2 for an illustration of the prescaler unit.
Figure 11-2. Prescaler for Timer/Counter0
clk I/O
Clear
PSR10
T0
Synchronization
clkT0
Note:
1. The synchronization logic on the input pins (T0) is shown in Figure 11-3 on page 55.
The prescaled clock has a frequency of fCLK_I/O/8, fCLK_I/O/64, fCLK_I/O/256, or fCLK_I/O/1024. See Table 11-6 on page
75 for details.
11.3.1.1
Prescaler Reset
The prescaler is free running, i.e., operates independently of the Clock Select logic of the Timer/CounterCounter,
and it is shared by the Timer/Counter Tn. 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 (CS2:0 = 2, 3, 4, or 5). 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.
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11.3.2
External Clock Source
An external clock source applied to the T0 pin can be used as Timer/Counter clock (clkTn). The Tn 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 11-3 on page 55 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 (CS2:0 = 7) or negative (CS2:0 = 6) edge it detects.
Figure 11-3. T0 Pin Sampling
D
Tn
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 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.
11.4
Counter Unit
The main part of the 16-bit Timer/Counter is the programmable 16-bit bi-directional counter unit. Figure 11-4 on
page 55 shows a block diagram of the counter and its surroundings.
Figure 11-4. Counter Unit Block Diagram
DATA BUS
(8-bit)
TOVn
(Int.Req.)
TEMP (8-bit)
Clock Select
Count
TCNTnH (8-bit)
TCNTnL (8-bit)
TCNTn (16-bit Counter)
Clear
Direction
Control Logic
clkTn
Edge
Detector
Tn
( From Prescaler )
TOP
BOTTOM
Signal description (internal signals):
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Count
Direction
Clear
clkT0
TOP
BOTTOM
Increment or decrement TCNT0 by 1.
Select between increment and decrement.
Clear TCNT0 (set all bits to zero).
Timer/Counter clock.
Signalize that TCNT0 has reached maximum value.
Signalize that TCNT0 has reached minimum value (zero).
The 16-bit counter is mapped into two 8-bit I/O memory locations: Counter High (TCNT0H) containing the upper
eight bits of the counter, and Counter Low (TCNT0L) containing the lower eight bits. The TCNT0H Register can
only be indirectly accessed by the CPU. When the CPU does an access to the TCNT0H I/O location, the CPU
accesses the high byte temporary register (TEMP). The temporary register is updated with the TCNT0H value
when the TCNT0L is read, and TCNT0H is updated with the temporary register value when TCNT0L is written. This
allows the CPU to read or write the entire 16-bit counter value within one clock cycle via the 8-bit data bus. It is
important to notice that there are special cases of writing to the TCNT0 Register when the counter is counting that
will give unpredictable results. The special cases are described in the sections where they are of importance.
Depending on the mode of operation used, the counter is cleared, incremented, or decremented at each timer
clock (clkT0). The 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, independent 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 Waveform Generation mode bits (WGM03:0) located in
the Timer/Counter Control Registers A and B (TCCR0A and TCCR0B). There are close connections between how
the counter behaves (counts) and how waveforms are generated on the Output Compare outputs OC0x. For more
details about advanced counting sequences and waveform generation, see “Modes of Operation” on page 61.
The Timer/Counter Overflow Flag (TOV0) is set according to the mode of operation selected by the WGM03:0 bits.
TOV0 can be used for generating a CPU interrupt.
11.5
Input Capture Unit
The Timer/Counter incorporates an Input Capture unit that can capture external events and give them a timestamp indicating time of occurrence. The external signal indicating an event, or multiple events, can be applied via
the ICP0 pin. The time-stamps can then be used to calculate frequency, duty-cycle, and other features of the signal
applied. Alternatively the time-stamps can be used for creating a log of the events.
The Input Capture unit is illustrated by the block diagram shown in Figure 11-5 on page 57. The elements of the
block diagram that are not directly a part of the Input Capture unit are gray shaded. The lower case “n” in register
and bit names indicates the Timer/Counter number.
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Figure 11-5. Input Capture Unit Block Diagram
DATA BUS
(8-bit)
TEMP (8-bit)
ICRnH (8-bit)
WRITE
ICRnL (8-bit)
TCNTnH (8-bit)
ICRn (16-bit Register)
ACO*
Analog
Comparator
ACIC*
TCNTnL (8-bit)
TCNTn (16-bit Counter)
ICNC
ICES
Noise
Canceler
Edge
Detector
ICFn (Int.Req.)
ICPn
When a change of the logic level (an event) occurs on the Input Capture pin (ICP0), alternatively on the Analog
Comparator output (ACO), and this change confirms to the setting of the edge detector, a capture will be triggered.
When a capture is triggered, the 16-bit value of the counter (TCNT0) is written to the Input Capture Register
(ICR0). The Input Capture Flag (ICF0) is set at the same system clock as the TCNT0 value is copied into ICR0
Register. If enabled (ICIE0 = 1), the Input Capture Flag generates an Input Capture interrupt. The ICF0 flag is automatically cleared when the interrupt is executed. Alternatively the ICF0 flag can be cleared by software by writing a
logical one to its I/O bit location.
Reading the 16-bit value in the Input Capture Register (ICR0) is done by first reading the low byte (ICR0L) and
then the high byte (ICR0H). When the low byte is read the high byte is copied into the high byte temporary register
(TEMP). When the CPU reads the ICR0H I/O location it will access the TEMP Register.
The ICR0 Register can only be written when using a Waveform Generation mode that utilizes the ICR0 Register for
defining the counter’s TOP value. In these cases the Waveform Generation mode (WGM03:0) bits must be set
before the TOP value can be written to the ICR0 Register. When writing the ICR0 Register the high byte must be
written to the ICR0H I/O location before the low byte is written to ICR0L.
For more information on how to access the 16-bit registers refer to “Accessing 16-bit Registers” on page 70.
11.5.1
Input Capture Trigger Source
The main trigger source for the Input Capture unit is the Input Capture pin (ICP0). Timer/Counter0 can alternatively
use the Analog Comparator output as trigger source for the Input Capture unit. The Analog Comparator is selected
as trigger source by setting the Analog Comparator Input Capture (ACIC) bit in “ACSR – Analog Comparator Control and Status Register”. Be aware that changing trigger source can trigger a capture. The Input Capture Flag
must therefore be cleared after the change.
Both the Input Capture pin (ICP0) and the Analog Comparator output (ACO) inputs are sampled using the same
technique as for the T0 pin (Figure 11-3 on page 55). The edge detector is also identical. However, when the noise
canceler is enabled, additional logic is inserted before the edge detector, which increases the delay by four system
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clock cycles. Note that the input of the noise canceler and edge detector is always enabled unless the Timer/Counter is set in a Waveform Generation mode that uses ICR0 to define TOP.
An Input Capture can be triggered by software by controlling the port of the ICP0 pin.
11.5.2
Noise Canceler
The noise canceler improves noise immunity by using a simple digital filtering scheme. The noise canceler input is
monitored over four samples, and all four must be equal for changing the output that in turn is used by the edge
detector.
The noise canceler is enabled by setting the Input Capture Noise Canceler (ICNC0) bit in Timer/Counter Control
Register B (TCCR0B). When enabled the noise canceler introduces additional four system clock cycles of delay
from a change applied to the input, to the update of the ICR0 Register. The noise canceler uses the system clock
and is therefore not affected by the prescaler.
11.5.3
Using the Input Capture Unit
The main challenge when using the Input Capture unit is to assign enough processor capacity for handling the
incoming events. The time between two events is critical. If the processor has not read the captured value in the
ICR0 Register before the next event occurs, the ICR0 will be overwritten with a new value. In this case the result of
the capture will be incorrect.
When using the Input Capture interrupt, the ICR0 Register should be read as early in the interrupt handler routine
as possible. Even though the Input Capture interrupt has relatively high priority, the maximum interrupt response
time is dependent on the maximum number of clock cycles it takes to handle any of the other interrupt requests.
Using the Input Capture unit in any mode of operation when the TOP value (resolution) is actively changed during
operation, is not recommended.
Measurement of an external signal’s duty cycle requires that the trigger edge is changed after each capture.
Changing the edge sensing must be done as early as possible after the ICR0 Register has been read. After a
change of the edge, the Input Capture Flag (ICF0) must be cleared by software (writing a logical one to the I/O bit
location). For measuring frequency only, the clearing of the ICF0 flag is not required (if an interrupt handler is
used).
11.6
Output Compare Units
The 16-bit comparator continuously compares TCNT0 with the Output Compare Register (OCR0x). If TCNT equals
OCR0x the comparator signals a match. A match will set the Output Compare Flag (OCF0x) at the next timer clock
cycle. If enabled (OCIE0x = 1), the Output Compare Flag generates an Output Compare interrupt. The OCF0x flag
is automatically cleared when the interrupt is executed. Alternatively the OCF0x 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 Waveform Generation mode (WGM03:0) bits and Compare Output mode
(COM0x1:0) bits. The TOP and BOTTOM signals are used by the Waveform Generator for handling the special
cases of the extreme values in some modes of operation (“Modes of Operation” on page 61).
A special feature of Output Compare unit A allows it to define the Timer/Counter TOP value (i.e., counter resolution). In addition to the counter resolution, the TOP value defines the period time for waveforms generated by the
Waveform Generator.
Figure 11-6 on page 59 shows a block diagram of the Output Compare unit. The small “n” in the register and bit
names indicates the device number (n = 0 for Timer/Counter 0), and the “x” indicates Output Compare unit (A/B).
The elements of the block diagram that are not directly a part of the Output Compare unit are gray shaded.
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Figure 11-6. Output Compare Unit, Block Diagram
DATA BUS
(8-bit)
TEMP (8-bit)
OCRnxH Buf. (8-bit)
OCRnxL Buf. (8-bit)
TCNTnH (8-bit)
OCRnx Buffer (16-bit Register)
OCRnxH (8-bit)
TCNTnL (8-bit)
TCNTn (16-bit Counter)
OCRnxL (8-bit)
OCRnx (16-bit Register)
= (16-bit Comparator )
OCFnx (Int.Req.)
TOP
BOTTOM
Waveform Generator
WGMn3:0
OCnx
COMnx1:0
The OCR0x Register is double buffered when using any of the twelve 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 Register 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. The content of the OCR0x (Buffer or Compare) Register is only changed by a write operation (the
Timer/Counter does not update this register automatically as the TCNT0 and ICR0 Register). Therefore OCR0x is
not read via the high byte temporary register (TEMP). However, it is a good practice to read the low byte first as
when accessing other 16-bit registers. Writing the OCR0x Registers must be done via the TEMP Register since the
compare of all 16 bits is done continuously. The high byte (OCR0xH) has to be written first. When the high byte I/O
location is written by the CPU, the TEMP Register will be updated by the value written. Then when the low byte
(OCR0xL) is written to the lower eight bits, the high byte will be copied into the upper 8-bits of either the OCR0x
buffer or OCR0x Compare Register in the same system clock cycle.
For more information of how to access the 16-bit registers refer to “Accessing 16-bit Registers” on page 70.
11.6.1
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 (0x) 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 COM01:0 bits settings define
whether the OC0x pin is set, cleared or toggled).
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11.6.2
Compare Match Blocking by TCNT0 Write
All CPU writes to the TCNT0 Register will block any compare match that occurs 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.
11.6.3
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 any of the Output Compare channels, independent 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 generation. Do not write the TCNT0 equal to TOP in PWM modes with
variable TOP values. The compare match for the TOP will be ignored and the counter will continue to 0xFFFF.
Similarly, do not write the TCNT0 value equal to BOTTOM when the counter is downcounting.
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 (0x) strobe bits in Normal mode.
The OC0x Register keeps its value 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.
11.7
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. Secondly the COM0x1:0 bits control
the OC0x pin output source. Figure 11-7 on page 61 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”.
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Figure 11-7. Compare Match Output Unit, Schematic (non-PWM Mode)
COMnx1
COMnx0
FOCnx
Waveform
Generator
D
Q
1
OCnx
DATA BUS
D
0
OCnx
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 generally independent of the Waveform Generation mode, but there are some exceptions. See Table 11-2 on page 73, Table 11-3 on page 73 and
Table 11-4 on page 73 for details.
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 72
The COM0x1:0 bits have no effect on the Input Capture unit.
11.7.1
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 73. For
fast PWM mode refer to Table 11-3 on page 73, and for phase correct and phase and frequency correct PWM refer
to Table 11-4 on page 73.
A change of the COM0x1:0 bits state will have effect at the first compare match after the bits are written. For nonPWM modes, the action can be forced to have immediate effect by using the 0x strobe bits.
11.8
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 (WGM03:0) 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
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PWM). For non-PWM modes the COM0x1:0 bits control whether the output should be set, cleared or toggle at a
compare match (“Compare Match Output Unit” on page 60)
For detailed timing information refer to “Timer/Counter Timing Diagrams” on page 69.
11.8.1
Normal Mode
The simplest mode of operation is the Normal mode (WGM03:0 = 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
16-bit value (MAX = 0xFFFF) and then restarts from the BOTTOM (0x0000). 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 17th 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 Input Capture unit is easy to use in Normal mode. However, observe that the maximum interval between the
external events must not exceed the resolution of the counter. If the interval between events are too long, the timer
overflow interrupt or the prescaler must be used to extend the resolution for the capture unit.
The Output Compare units 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.
11.8.2
Clear Timer on Compare Match (CTC) Mode
In Clear Timer on Compare or CTC mode (WGM03:0 = 4 or 12), the OCR0A or ICR0 Register are used to manipulate the counter resolution. In CTC mode the counter is cleared to zero when the counter value (TCNT0) matches
either the OCR0A (WGM03:0 = 4) or the ICR0 (WGM03:0 = 12). The OCR0A or ICR0 define 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.
The timing diagram for the CTC mode is shown in Figure 11-8 on page 62. The counter value (TCNT0) increases
until a compare match occurs with either OCR0A or ICR0, and then counter (TCNT0) is cleared.
Figure 11-8. CTC Mode, Timing Diagram
OCnA Interrupt Flag Set
or ICFn Interrupt Flag Set
(Interrupt on TOP)
TCNTn
OCnA
(Toggle)
Period
(COMnA1:0 = 1)
1
2
3
4
An interrupt can be generated at each time the counter value reaches the TOP value by either using the OCF0A or
ICF0 flag according to the register used to define the TOP value. If the interrupt is enabled, the interrupt handler
routine can be used for updating the TOP value. However, changing the 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 or ICR0 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
(0xFFFF) and wrap around starting at 0x0000 before the compare match can occur. In many cases this feature is
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not desirable. An alternative will then be to use the fast PWM mode using OCR0A for defining TOP (WGM03:0 =
15) since the OCR0A then will be double buffered.
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 (DDR_OC0A = 1). The waveform
generated will have a maximum frequency of 0A = fclk_I/O/2 when OCR0A is set to zero (0x0000). The waveform frequency is defined by the following equation:
f clk_I/O
f OCnA = --------------------------------------------------2  N   1 + OCRnA 
The N variable represents the prescaler 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 0x0000.
11.8.3
Fast PWM Mode
The fast Pulse Width Modulation or fast PWM mode (WGM03:0 = 5, 6, 7, 14, or 15) provides a high frequency
PWM waveform generation option. The fast PWM differs from the other PWM options by its single-slope operation.
The counter counts from BOTTOM to TOP then restarts from BOTTOM. In non-inverting 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 output is set on compare match and cleared at BOTTOM. Due to the singleslope operation, the operating frequency of the fast PWM mode can be twice as high as the phase correct and
phase and frequency correct PWM modes that use dual-slope operation. This high frequency makes the fast PWM
mode well suited for power regulation, rectification, and DAC applications. High frequency allows physically small
sized external components (coils, capacitors), hence reduces total system cost.
The PWM resolution for fast PWM can be fixed to 8-, 9-, or 10-bit, or defined by either ICR0 or OCR0A. The minimum resolution allowed is 2-bit (ICR0 or OCR0A set to 0x0003), and the maximum resolution is 16-bit (ICR0 or
OCR0A set to MAX). The PWM resolution in bits can be calculated by using the following equation:
log  TOP + 1 
R FPWM = ----------------------------------log  2 
In fast PWM mode the counter is incremented until the counter value matches either one of the fixed values
0x00FF, 0x01FF, or 0x03FF (WGM03:0 = 5, 6, or 7), the value in ICR0 (WGM03:0 = 14), or the value in OCR0A
(WGM03:0 = 15). The counter is then cleared at the following timer clock cycle. The timing diagram for the fast
PWM mode is shown in Figure 11-9 on page 64. The figure shows fast PWM mode when OCR0A or ICR0 is used
to define TOP. The TCNT0 value is in the timing diagram shown as a histogram for illustrating the single-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. The OC0x interrupt flag will be set when
a compare match occurs.
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Figure 11-9. Fast PWM Mode, Timing Diagram
OCRnx/TOP Update and
TOVn Interrupt Flag Set and
OCnA Interrupt Flag Set
or ICFn Interrupt Flag Set
(Interrupt on TOP)
TCNTn
OCnx
(COMnx1:0 = 2)
OCnx
(COMnx1:0 = 3)
Period
1
2
3
4
5
6
7
8
The Timer/Counter Overflow Flag (TOV0) is set each time the counter reaches TOP. In addition the OC0A or ICF0
flag is set at the same timer clock cycle as TOV0 is set when either OCR0A or ICR0 is used for defining the TOP
value. If one of the interrupts are enabled, the interrupt handler routine can be used for updating the TOP and compare values.
When changing the TOP value the program must ensure that the new TOP value is higher or equal to the value of
all of the Compare Registers. If the TOP value is lower than any of the Compare Registers, a compare match will
never occur between the TCNT0 and the OCR0x. Note that when using fixed TOP values the unused bits are
masked to zero when any of the OCR0x Registers are written.
The procedure for updating ICR0 differs from updating OCR0A when used for defining the TOP value. The ICR0
Register is not double buffered. This means that if ICR0 is changed to a low value when the counter is running with
none or a low prescaler value, there is a risk that the new ICR0 value written is lower than the current value of
TCNT0. The result will then be that the counter will miss the compare match at the TOP value. The counter will
then have to count to the MAX value (0xFFFF) and wrap around starting at 0x0000 before the compare match can
occur. The OCR0A Register however, is double buffered. This feature allows the OCR0A I/O location to be written
anytime. When the OCR0A I/O location is written the value written will be put into the OCR0A Buffer Register. The
OCR0A Compare Register will then be updated with the value in the Buffer Register at the next timer clock cycle
the TCNT0 matches TOP. The update is done at the same timer clock cycle as the TCNT0 is cleared and the
TOV0 flag is set.
Using the ICR0 Register for defining TOP works well when using fixed TOP values. By using ICR0, the OCR0A
Register is free to be used for generating a PWM output on OC0A. However, if the base PWM frequency is actively
changed (by changing the TOP value), using the OCR0A as TOP is clearly a better choice due to its double buffer
feature.
In fast PWM mode, the compare units allow 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 (see Table 11-3 on page 73). The actual OC0x value will only be visible on the port pin if
the data direction for the port pin is set as output (DDR_OC0x). 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).
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The PWM frequency for the output can be calculated by the following equation:
f clk_I/O
f OCnxPWM = ----------------------------------N   1 + TOP 
The N variable represents the prescaler divider (1, 8, 64, 256, or 1024).
The extreme values for the OCR0x Register represents special cases when generating a PWM waveform output in
the fast PWM mode. If the OCR0x is set equal to BOTTOM (0x0000) the output will be a narrow spike for each
TOP+1 timer clock cycle. Setting the OCR0x equal to TOP will result in a constant high or low output (depending
on the polarity of the output set by the COM0x1:0 bits.)
A frequency (with 50% duty cycle) waveform output in fast PWM mode can be achieved by setting OC0A to toggle
its logical level on each compare match (COM0A1:0 = 1). The waveform generated will have a maximum frequency of f0A = fclk_I/O/2 when OCR0A is set to zero (0x0000). 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.
11.8.4
Phase Correct PWM Mode
The phase correct Pulse Width Modulation or phase correct PWM mode (WGM03:0 = 1, 2, 3, 10, or 11) provides a
high resolution phase correct PWM waveform generation option. The phase correct PWM mode is, like the phase
and frequency correct PWM mode, based on a dual-slope operation. The counter counts repeatedly from BOTTOM (0x0000) to TOP and then from TOP to BOTTOM. In non-inverting 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.
The PWM resolution for the phase correct PWM mode can be fixed to 8-, 9-, or 10-bit, or defined by either ICR0 or
OCR0A. The minimum resolution allowed is 2-bit (ICR0 or OCR0A set to 0x0003), and the maximum resolution is
16-bit (ICR0 or OCR0A set to MAX). The PWM resolution in bits can be calculated by using the following equation:
log  TOP + 1 
R PCPWM = ----------------------------------log  2 
In phase correct PWM mode the counter is incremented until the counter value matches either one of the fixed values 0x00FF, 0x01FF, or 0x03FF (WGM03:0 = 1, 2, or 3), the value in ICR0 (WGM03:0 = 10), or the value in
OCR0A (WGM03:0 = 11). The counter has then reached the TOP and 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 11-10 on page 66. The figure shows phase correct PWM mode when OCR0A or ICR0 is used to define
TOP. 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. The OC0x interrupt flag will be set when a compare
match occurs.
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Figure 11-10. Phase Correct PWM Mode, Timing Diagram
OCRnx/TOP Update and
OCnA Interrupt Flag Set
or ICFn Interrupt Flag Set
(Interrupt on TOP)
TOVn Interrupt Flag Set
(Interrupt on Bottom)
TCNTn
OCnx
(COMnx1:0 = 2)
OCnx
(COMnx1:0 = 3)
Period
1
2
3
4
The Timer/Counter Overflow Flag (TOV0) is set each time the counter reaches BOTTOM. When either OCR0A or
ICR0 is used for defining the TOP value, the OC0A or ICF0 flag is set accordingly at the same timer clock cycle as
the OCR0x Registers are updated with the double buffer value (at TOP). The interrupt flags can be used to generate an interrupt each time the counter reaches the TOP or BOTTOM value.
When changing the TOP value the program must ensure that the new TOP value is higher or equal to the value of
all of the Compare Registers. If the TOP value is lower than any of the Compare Registers, a compare match will
never occur between the TCNT0 and the OCR0x. Note that when using fixed TOP values, the unused bits are
masked to zero when any of the OCR0x Registers are written. As the third period shown in Figure 11-10 on page
66 illustrates, changing the TOP actively while the Timer/Counter is running in the phase correct mode can result in
an unsymmetrical output. The reason for this can be found in the time of update of the OCR0x Register. Since the
OCR0x update occurs at TOP, the PWM period starts and ends at TOP. This implies that the length of the falling
slope is determined by the previous TOP value, while the length of the rising slope is determined by the new TOP
value. When these two values differ the two slopes of the period will differ in length. The difference in length gives
the unsymmetrical result on the output.
It is recommended to use the phase and frequency correct mode instead of the phase correct mode when changing the TOP value while the Timer/Counter is running. When using a static TOP value there are practically no
differences between the two modes of operation.
In phase correct PWM mode, the compare units allow 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 (See Table 11-4 on page 73). The actual OC0x value will only be visible on the port pin
if the data direction for the port pin is set as output (DDR_OC0x). The PWM waveform is generated by setting (or
clearing) the OC0x Register at the compare match between OCR0x and TCNT0 when the counter increments, and
clearing (or setting) 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 = ----------------------------2  N  TOP
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The N variable represents the prescaler divider (1, 8, 64, 256, or 1024).
The extreme values for the OCR0x Register represent special cases when generating a PWM waveform output in
the phase correct PWM mode. If the OCR0x is set equal to BOTTOM the output will be continuously low and if set
equal to TOP the output will be continuously high for non-inverted PWM mode. For inverted PWM the output will
have the opposite logic values.
11.8.5
Phase and Frequency Correct PWM Mode
The phase and frequency correct Pulse Width Modulation, or phase and frequency correct PWM mode (WGM03:0
= 8 or 9) provides a high resolution phase and frequency correct PWM waveform generation option. The phase
and frequency correct PWM mode is, like the phase correct PWM mode, based on a dual-slope operation. The
counter counts repeatedly from BOTTOM (0x0000) to TOP and then from TOP to BOTTOM. In non-inverting 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 Compare Output mode, the
operation is inverted. The dual-slope operation gives a lower maximum operation frequency compared to the single-slope operation. However, due to the symmetric feature of the dual-slope PWM modes, these modes are
preferred for motor control applications.
The main difference between the phase correct, and the phase and frequency correct PWM mode is the time the
OCR0x Register is updated by the OCR0x Buffer Register, (see Figure 11-10 on page 66 and Figure 11-11 on
page 68).
The PWM resolution for the phase and frequency correct PWM mode can be defined by either ICR0 or OCR0A.
The minimum resolution allowed is 2-bit (ICR0 or OCR0A set to 0x0003), and the maximum resolution is 16-bit
(ICR0 or OCR0A set to MAX). The PWM resolution in bits can be calculated using the following equation:
log  TOP + 1 
R PFCPWM = ----------------------------------log  2 
In phase and frequency correct PWM mode the counter is incremented until the counter value matches either the
value in ICR0 (WGM03:0 = 8), or the value in OCR0A (WGM03:0 = 9). The counter has then reached the TOP and
changes the count direction. The TCNT0 value will be equal to TOP for one timer clock cycle. The timing diagram
for the phase correct and frequency correct PWM mode is shown on Figure 11-11 on page 68. The figure shows
phase and frequency correct PWM mode when OCR0A or ICR0 is used to define TOP. 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. The OC0x interrupt flag will be set when a compare match occurs.
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Figure 11-11. Phase and Frequency Correct PWM Mode, Timing Diagram
OCnA Interrupt Flag Set
or ICFn Interrupt Flag Set
(Interrupt on TOP)
OCRnx/TOP Updateand
TOVn Interrupt Flag Set
(Interrupt on Bottom)
TCNTn
OCnx
(COMnx1:0 = 2)
OCnx
(COMnx1:0 = 3)
Period
1
2
3
4
The Timer/Counter Overflow Flag (TOV0) is set at the same timer clock cycle as the OCR0x Registers are updated
with the double buffer value (at BOTTOM). When either OCR0A or ICR0 is used for defining the TOP value, the
OC0A or ICF0 flag set when TCNT0 has reached TOP. The interrupt flags can then be used to generate an interrupt each time the counter reaches the TOP or BOTTOM value.
When changing the TOP value the program must ensure that the new TOP value is higher or equal to the value of
all of the Compare Registers. If the TOP value is lower than any of the Compare Registers, a compare match will
never occur between the TCNT0 and the OCR0x.
As Figure 11-11 on page 68 shows the output generated is, in contrast to the phase correct mode, symmetrical in
all periods. Since the OCR0x Registers are updated at BOTTOM, the length of the rising and the falling slopes will
always be equal. This gives symmetrical output pulses and is therefore frequency correct.
Using the ICR0 Register for defining TOP works well when using fixed TOP values. By using ICR0, the OCR0A
Register is free to be used for generating a PWM output on OC0A. However, if the base PWM frequency is actively
changed by changing the TOP value, using the OCR0A as TOP is clearly a better choice due to its double buffer
feature.
In phase and frequency correct PWM mode, the compare units allow 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 (See Table 11-4 on page 73). The actual OC0x value will only be visible
on the port pin if the data direction for the port pin is set as output (DDR_OC0x). The PWM waveform is generated
by setting (or clearing) the OC0x Register at the compare match between OCR0x and TCNT0 when the counter
increments, and clearing (or setting) the OC0x Register at compare match between OCR0x and TCNT0 when the
counter decrements. The PWM frequency for the output when using phase and frequency correct PWM can be calculated by the following equation:
f clk_I/O
f OCnxPFCPWM = ----------------------------2  N  TOP
The N variable represents the prescaler divider (1, 8, 64, 256, or 1024).
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The extreme values for the OCR0x Register represents special cases when generating a PWM waveform output in
the phase correct PWM mode. If the OCR0x is set equal to BOTTOM the output will be continuously low and if set
equal to TOP the output will be set to high for non-inverted PWM mode. For inverted PWM the output will have the
opposite logic values.
11.9
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, and when the OCR0x Register is updated with the OCR0x buffer value (only for modes utilizing double buffering). Figure 11-12 on page 69
shows a timing diagram for the setting of OCF0x.
Figure 11-12. Timer/Counter Timing Diagram, Setting of OCF0x, no Prescaling
clkI/O
clkTn
(clkI/O /1)
TCNTn
OCRnx - 1
OCRnx
OCRnx
OCRnx + 1
OCRnx + 2
OCRnx Value
OCFnx
Figure 11-13 on page 69 shows the same timing data, but with the prescaler enabled.
Figure 11-13. 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 11-14 on page 70 shows the count sequence close to TOP in various modes. When using phase and frequency correct PWM mode the OCR0x Register is updated at BOTTOM. The timing diagrams will be the same, but
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TOP should be replaced by BOTTOM, TOP-1 by BOTTOM+1 and so on. The same renaming applies for modes
that set the TOV0 flag at BOTTOM.
Figure 11-14. Timer/Counter Timing Diagram, no Prescaling
clkI/O
clkTn
(clkI/O /1)
TCNTn
(CTC and FPWM)
TCNTn
(PC and PFC PWM)
TOP - 1
TOP
BOTTOM
BOTTOM + 1
TOP - 1
TOP
TOP - 1
TOP - 2
TOVn (FPWM)
and ICFn (if used
as TOP)
OCRnx
(Update at TOP)
Old OCRnx Value
New OCRnx Value
Figure 11-15 on page 70 shows the same timing data, but with the prescaler enabled.
Figure 11-15. Timer/Counter Timing Diagram, with Prescaler (fclk_I/O/8)
clkI/O
clkTn
(clkI/O/8)
TCNTn
(CTC and FPWM)
TCNTn
(PC and PFC PWM)
TOP - 1
TOP
BOTTOM
BOTTOM + 1
TOP - 1
TOP
TOP - 1
TOP - 2
TOVn (FPWM)
and ICF n (if used
as TOP)
OCRnx
(Update at TOP)
Old OCRnx Value
New OCRnx Value
11.10 Accessing 16-bit Registers
The TCNT0, OCR0A/B, and ICR0 are 16-bit registers that can be accessed by the AVR CPU via the 8-bit data bus.
The 16-bit register must be byte accessed using two read or write operations. Each 16-bit timer has a single 8-bit
register for temporary storing of the high byte of the 16-bit access. The same temporary register is shared between
all 16-bit registers within each 16-bit timer. Accessing the low byte triggers the 16-bit read or write operation. When
the low byte of a 16-bit register is written by the CPU, the high byte stored in the temporary register, and the low
byte written are both copied into the 16-bit register in the same clock cycle. When the low byte of a 16-bit register is
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read by the CPU, the high byte of the 16-bit register is copied into the temporary register in the same clock cycle as
the low byte is read.
Not all 16-bit accesses uses the temporary register for the high byte. Reading the OCR0A/B 16-bit registers does
not involve using the temporary register.
To do a 16-bit write, the high byte must be written before the low byte. For a 16-bit read, the low byte must be read
before the high byte.
The following code example shows how to access the 16-bit timer registers assuming that no interrupts updates
the temporary register. The same principle can be used directly for accessing the OCR0A/B and ICR0 Registers.
Assembly Code Example
...
; Set TCNT0 to 0x01FF
ldi r17,0x01
ldi r16,0xFF
out TCNT0H,r17
out TCNT0L,r16
; Read TCNT0 into r17:r16
in r16,TCNT0L
in r17,TCNT0H
...
Note:
See “Code Examples” on page 5.
The code example returns the TCNT0 value in the r17:r16 register pair.
It is important to notice that accessing 16-bit registers are atomic operations. If an interrupt occurs between the two
instructions accessing the 16-bit register, and the interrupt code updates the temporary register by accessing the
same or any other of the 16-bit timer registers, then the result of the access outside the interrupt will be corrupted.
Therefore, when both the main code and the interrupt code update the temporary register, the main code must disable the interrupts during the 16-bit access.
The following code example shows how to do an atomic read of the TCNT0 Register contents. Reading any of the
OCR0A/B or ICR0 Registers can be done by using the same principle.
Assembly Code Example
TIM16_ReadTCNT0:
; Save global interrupt flag
in r18,SREG
; Disable interrupts
cli
; Read TCNT0 into r17:r16
in r16,TCNT0L
in r17,TCNT0H
; Restore global interrupt flag
out SREG,r18
ret
Note:
See “Code Examples” on page 5.
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The code example returns the TCNT0 value in the r17:r16 register pair.
The following code example shows how to do an atomic write of the TCNT0 Register contents. Writing any of the
OCR0A/B or ICR0 Registers can be done by using the same principle.
Assembly Code Example
TIM16_WriteTCNT0:
; Save global interrupt flag
in r18,SREG
; Disable interrupts
cli
; Set TCNT0 to r17:r16
out TCNT0H,r17
out TCNT0L,r16
; Restore global interrupt flag
out SREG,r18
ret
Note:
See “Code Examples” on page 5.
The code example requires that the r17:r16 register pair contains the value to be written to TCNT0.
11.10.1
Reusing the Temporary High Byte Register
If writing to more than one 16-bit register where the high byte is the same for all registers written, then the high byte
only needs to be written once. However, note that the same rule of atomic operation described previously also
applies in this case.
11.11 Register Description
11.11.1
TCCR0A – Timer/Counter0 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
0x2E
TCCR0A
• Bits 7:6 – COM0A1:0: Compare Output Mode for Channel A
• Bits 5:4 – COM0B1:0: Compare Output Mode for Channel B
The COM0A1:0 and COM0B1:0 control the behaviour of Output Compare pins OC0A and OC0B, respectively. If
one or both COM0A1:0 bits are written to one, the OC0A output overrides the normal port functionality of the I/O
pin it is connected to. Similarly, if one or both COM0B1:0 bit are written to one, the OC0B output overrides the normal port functionality of the I/O pin it is connected to.
Note, however, that the Data Direction Register (DDR) bit corresponding to the OC0A or OC0B pin must be set in
order to enable the output driver.
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When OC0A or OC0B is connected to the pin, the function of COM0x1:0 bits depends on the WGM03:0 bits. Table
11-2 shows the COM0x1:0 bit functionality when the WGM03:0 bits are set to a Normal or CTC (non-PWM) Mode.
Table 11-2.
COM0A1/
COM0B1
Compare Output in Non-PWM Modes
COM0A0
COM0B0
Description
0
Normal port operation: OC0A/OC0B disconnected
1
Toggle OC0A/OC0B on compare match
0
Clear (set low) OC0A/OC0B on compare match
1
Set (high) OC0A/OC0B on compare match
0
1
Table 11-3 shows the COM0x1:0 bit functionality when the WGM03:0 bits are set to one of the Fast PWM Modes.
Table 11-3.
COM0A1/
COM0B1
Compare Output in Fast PWM Modes
COM0A0/
COM0B0
0
Normal port operation: OC0A/OC0B disconnected
1
WGM03 = 0: Normal port operation, OC0A/OC0B disconnected
WGM03 = 1: Toggle OC0A on compare match, OC0B reserved
0
Clear OC0A/OC0B on compare match
Set OC0A/OC0B at BOTTOM (non-inverting mode)
1
Set OC0A/OC0B on compare match
Clear OC0A/OC0B at BOTTOM (inverting mode)
0
1 (1)
Note:
Description
1. A special case occurs when OCR0A/OCR0B equals TOP and COM0A1/COM0B1 is set. In this case the compare
match is ignored, but set or clear is done at BOTTOM. See “Fast PWM Mode” on page 63 for more details.
Table 11-4 shows the COM0x1:0 bit functionality when the WGM03:0 bits are set to the phase correct or the phase
and frequency correct, PWM mode.
Table 11-4.
COM0A1/
COM0B1
Compare Output in Phase Correct and Phase & Frequency Correct PWM Modes
COM0A0/
COM0B0
0
Normal port operation: OC0A/OC0B disconnected.
1
WGM03 = 0: Normal port operation, OC0A/OC0B disconnected
WGM03 = 1: Toggle OC0A on compare match, OC0B reserved
0
Counting up: Clear OC0A/OC0B on compare match
Counting down: Set OC0A/OC0B on compare match
1
Counting up: Set OC0A/OC0B on compare match
Counting down: Clear OC0A/OC0B on compare match
0
1 (1)
Note:
Description
1. A special case occurs when OCR0A/OCR0B equals TOP and COM0A1/COM0B1 is set. “Phase Correct PWM
Mode” on page 65 for more details.
• Bits 1:0 – WGM01:0: Waveform Generation Mode
Combined with WGM03:2 bits of TCCR0B, these bits control the counting sequence of the counter, the source for
maximum (TOP) counter value, and what type of waveform to generate. See Table 11-5. Modes of operation sup-
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ported by the Timer/Counter unit are: Normal mode (counter), Clear Timer on Compare match (CTC) mode, and
three types of Pulse Width Modulation (PWM) modes. (“Modes of Operation” on page 61).
Table 11-5.
11.11.2
Waveform Generation Modes
Mode
WGM0
3:0
0
Mode of Operation
TOP
Update of
OCR0x at
TOV0 Flag
Set on
0000
Normal
0xFFFF
Immediate
MAX
1
0001
PWM, Phase Correct, 8-bit
0x00FF
TOP
BOTTOM
2
0010
PWM, Phase Correct, 9-bit
0x01FF
TOP
BOTTOM
3
0011
PWM, Phase Correct, 10-bit
0x03FF
TOP
BOTTOM
4
0100
CTC (Clear Timer on Compare)
OCR0A
Immediate
MAX
5
0101
Fast PWM, 8-bit
0x00FF
TOP
TOP
6
0110
Fast PWM, 9-bit
0x01FF
TOP
TOP
7
0111
Fast PWM, 10-bit
0x03FF
TOP
TOP
8
1000
PWM, Phase & Freq. Correct
ICR0
BOTTOM
BOTTOM
9
1001
PWM, Phase & Freq. Correct
OCR0A
BOTTOM
BOTTOM
10
1010
PWM, Phase Correct
ICR0
TOP
BOTTOM
11
1011
PWM, Phase Correct
OCR0A
TOP
BOTTOM
12
1100
CTC (Clear Timer on Compare)
ICR0
Immediate
MAX
13
1101
(Reserved)
–
–
–
14
1110
Fast PWM
ICR0
TOP
TOP
15
1111
Fast PWM
OCR0A
TOP
TOP
TCCR0B – Timer/Counter0 Control Register B
Bit
7
6
5
4
3
2
1
0
ICNC0
ICES0
–
WGM03
WGM02
CS02
CS01
CS00
Read/Write
R/W
R/W
R
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
0x2D
TCCR0B
• Bit 7 – ICNC0: Input Capture Noise Canceler
Setting this bit (to one) activates the Input Capture Noise Canceler. When the noise canceler is activated, the input
from the Input Capture pin (ICP0) is filtered. The filter function requires four successive equal valued samples of
the ICP0 pin for changing its output. The Input Capture is therefore delayed by four oscillator cycles when the noise
canceler is enabled.
• Bit 6 – ICES0: Input Capture Edge Select
This bit selects which edge on the Input Capture pin (ICP0) that is used to trigger a capture event. When the ICES0
bit is written to zero, a falling (negative) edge is used as trigger, and when the ICES0 bit is written to one, a rising
(positive) edge will trigger the capture.
When a capture is triggered according to the ICES0 setting, the counter value is copied into the Input Capture Register (ICR0). The event will also set the Input Capture Flag (ICF0), and this can be used to cause an Input Capture
Interrupt, if this interrupt is enabled.
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When the ICR0 is used as TOP value (see description of the WGM03:0 bits located in the TCCR0A and the
TCCR0B Register), the ICP0 is disconnected and consequently the Input Capture function is disabled.
• Bit 5 – Reserved Bit
This bit is reserved for future use. For ensuring compatibility with future devices, this bit must be written to zero
when TCCR0B is written.
• Bits 4:3 – WGM03:2: Waveform Generation Mode
See “TCCR0A – Timer/Counter0 Control Register A” on page 72.
• Bits 2:0 – CS02:0: Clock Select
The three Clock Select bits set the clock source to be used by the Timer/Counter, see Figure 11-12 and Figure 1113.
Table 11-6.
Clock Select Bit Description
CS02
CS01
CS00
Description
0
0
0
No clock source (Timer/Counter stopped)
0
0
1
clkI/O/1 (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.
11.11.3
TCCR0C – Timer/Counter0 Control Register C
Bit
7
6
5
4
3
2
1
FOC0A
FOC0B
–
–
–
–
–
–
Read/Write
W
W
R
R
R
R
R
R
Initial Value
0
0
0
0
0
0
0
0
0x2C
0
TCCR0C
• Bit 7 – FOC0A: Force Output Compare for Channel A
• Bit 6 – FOC0B: Force Output Compare for Channel B
The FOC0A/FOC0B bits are only active when the WGM03:0 bits specifies a non-PWM mode. However, for ensuring compatibility with future devices, these bits must be set to zero when TCCR0A is written when operating in a
PWM mode. When writing a logical one to the FOC0A/FOC0B bit, an immediate compare match is forced on the
Waveform Generation unit. The OC0A/OC0B output is changed according to its COM0x1:0 bits setting. Note that
the FOC0A/FOC0B bits are implemented as strobes. Therefore it is the value present in the COM0x1:0 bits that
determine the effect of the forced compare.
A FOC0A/FOC0B strobe will not generate any interrupt nor will it clear the timer in Clear Timer on Compare match
(CTC) mode using OCR0A as TOP.
The FOC0A/FOC0B bits are always read as zero.
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• Bits 5:0 – Reserved Bits
These bits are reserved for future use. For ensuring compatibility with future devices, these bits must be written to
zero when the register is written.
11.11.4
TCNT0H and TCNT0L – Timer/Counter0
Bit
7
6
5
4
3
0x29
TCNT0[15:8]
0x28
TCNT0[7:0]
2
1
0
TCNT0H
TCNT0L
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 two Timer/Counter I/O locations (TCNT0H and TCNT0L, combined TCNT0) give direct access, both for read
and for write operations, to the Timer/Counter unit 16-bit counter. To ensure that both the high and low bytes are
read and written simultaneously when the CPU accesses these registers, the access is performed using an 8-bit
temporary high byte register (TEMP). This temporary register is shared by all the other 16-bit registers. See
“Accessing 16-bit Registers” on page 70.
Modifying the counter (TCNT0) while the counter is running introduces a risk of missing a compare match between
TCNT0 and one of the OCR0x Registers.
Writing to the TCNT0 Register blocks (removes) the compare match on the following timer clock for all compare
units.
11.11.5
OCR0AH and OCR0AL – Output Compare Register 0 A
Bit
11.11.6
7
6
5
4
3
0x27
OCR1A[15:8]
0x26
OCR1A[7:0]
2
1
0
OCR0AH
OCR0AL
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
2
1
0
OCR0BH and OCR0BL – Output Compare Register 0 B
Bit
7
6
5
4
3
0x25
OCR0B[15:8]
0x24
OCR0B[7:0]
OCR0BH
OCR0BL
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 Registers contain a 16-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
OC0x pin.
The Output Compare Registers are 16-bit in size. To ensure that both the high and low bytes are written simultaneously when the CPU writes to these registers, the access is performed using an 8-bit temporary high byte register
(TEMP). This temporary register is shared by all the other 16-bit registers. See “Accessing 16-bit Registers” on
page 70.
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11.11.7
ICR0H and ICR0L – Input Capture Register 0
Bit
7
6
5
4
3
0x23
ICR0[15:8]
0x22
ICR0[7:0]
2
1
0
ICR0H
ICR0L
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 Input Capture is updated with the counter (TCNT0) value each time an event occurs on the ICP0 pin (or
optionally on the Analog Comparator output for Timer/Counter0). The Input Capture can be used for defining the
counter TOP value.
The Input Capture Register is 16-bit in size. To ensure that both the high and low bytes are read simultaneously
when the CPU accesses these registers, the access is performed using an 8-bit temporary high byte register
(TEMP). This temporary register is shared by all the other 16-bit registers. “Accessing 16-bit Registers” on page
70.
11.11.8
TIMSK0 – Timer/Counter Interrupt Mask Register 0
Bit
7
6
5
4
3
2
1
0
0x2B
–
–
ICIE0
–
–
OCIE0B
OCIE0A
TOIE0
Read/Write
R
R
R/W
R
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
TIMSK0
• Bits 7:6, 4:3 – Reserved Bits
These bits are reserved for future use. For ensuring compatibility with future devices, these bits must be written to
zero when the register is written.
• Bit 5 – ICIE0: Timer/Counter0, Input Capture Interrupt Enable
When this bit is written to one, and the I-flag in the Status Register is set (interrupts globally enabled), the
Timer/Counter0 Input Capture interrupt is enabled. The
corresponding Interrupt Vector (See “Interrupts” on page 66.) is executed when the
ICF0 Flag, located in TIFR0, is set.
• Bit 2 – OCIE0B: Timer/Counter0, Output Compare B Match Interrupt Enable
When this bit is written to one, and the I-flag in the Status Register is set (interrupts globally enabled), the
Timer/Counter0 Output Compare B Match interrupt is enabled. The corresponding Interrupt Vector (see “Interrupts” on page 35) is executed when the OCF0B flag, located in TIFR0, is set.
• Bit 1 – OCIE0A: Timer/Counter0, Output Compare A Match Interrupt Enable
When this bit is written to one, and the I-flag in the Status Register is set (interrupts globally enabled), the
Timer/Counter0 Output Compare A Match interrupt is enabled. The corresponding Interrupt Vector (see “Interrupts” on page 35) is executed when the OCF0A flag, located in TIFR0, is set.
• Bit 0 – TOIE0: Timer/Counter0, Overflow Interrupt Enable
When this bit is written to one, and the I-flag in the Status Register is set (interrupts globally enabled), the
Timer/Counter0 Overflow interrupt is enabled. The corresponding Interrupt Vector (see “Interrupts” on page 35) is
executed when the TOV0 flag, located in TIFR0, is set.
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11.11.9
TIFR0 – Timer/Counter Interrupt Flag Register 0
Bit
7
6
5
4
3
2
1
0
0x2A
–
–
ICF0
–
–
OCF0B
OCF0A
TOV0
Read/Write
R
R
R/W
R
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
TIFR0
• Bits 7:6, 4:3 – Reserved Bits
These bits are reserved for future use. For ensuring compatibility with future devices, these bits must be written to
zero when the register is written.
• Bit 5 – ICF0: Timer/Counter0, Input Capture Flag
This flag is set when a capture event occurs on the ICP0 pin. When the Input Capture Register (ICR0) is set by the
WGM03:0 to be used as the TOP value, the ICF0 flag is set when the counter reaches the TOP value.
ICF0 is automatically cleared when the Input Capture Interrupt Vector is executed. Alternatively, ICF0 can be
cleared by writing a logic one to its bit location.
• Bit 2 – OCF1B: Timer/Counter0, Output Compare B Match Flag
This flag is set in the timer clock cycle after the counter (TCNT0) value matches the Output Compare Register B
(OCR0B).
Note that a Forced Output Compare (0B) strobe will not set the OCF0B flag.
OCF1B is automatically cleared when the Output Compare Match B Interrupt Vector is executed. Alternatively,
OCF1B can be cleared by writing a logic one to its bit location.
• Bit 1 – OCF0A: Timer/Counter0, Output Compare A Match Flag
This flag is set in the timer clock cycle after the counter (TCNT0) value matches the Output Compare Register A
(OCR0A).
Note that a Forced Output Compare (1A) strobe will not set the OCF0A flag.
OCF0A is automatically cleared when the Output Compare Match A Interrupt Vector is executed. Alternatively,
OCF0A can be cleared by writing a logic one to its bit location.
• Bit 0 – TOV0: Timer/Counter0, Overflow Flag
The setting of this flag is dependent of the WGM03:0 bits setting. In Normal and CTC modes, the TOV0 flag is set
when the timer overflows. See Table 11-5 on page 74 for the TOV0 flag behavior when using another WGM03:0 bit
setting.
TOV0 is automatically cleared when the Timer/Counter0 Overflow Interrupt Vector is executed. Alternatively, TOV0
can be cleared by writing a logic one to its bit location.
11.11.10 GTCCR – General Timer/Counter Control Register
Bit
7
6
5
4
3
2
1
0
0x2F
TSM
–
–
–
–
–
–
PSR
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 PSR bit is kept, hence keeping the Prescaler Reset signal asserted. This ensures that the Timer/Counter
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is halted and can be configured without the risk of advancing during configuration. When the TSM bit is written to
zero, the PSR bit is cleared by hardware, and the Timer/Counter start counting.
• Bit 0 – PSR: Prescaler 0 Reset Timer/Counter 0
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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12. 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 12-1.
Figure 12-1. Analog Comparator Block Diagram.
See Figure 1-1 on page 2 for pin use of analog comparator, and Table 10-4 on page 49 and Table 10-5 on page 50
for alternate pin usage.
12.1
12.1.1
Register Description
ACSR – Analog Comparator Control and Status Register
Bit
7
6
5
4
3
2
1
0
0x1F
ACD
–
ACO
ACI
ACIE
ACIC
ACIS1
ACIS0
Read/Write
R/W
R
R
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
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, thus reducing 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.
• Bits 6 – Res: Reserved Bit
This bit is reserved and will always read zero.
• Bit 5 – ACO: Analog Comparator Output
Enables output of analog comparator. The output of the analog comparator is synchronized and then directly connected to ACO. The synchronization introduces a delay of 1 - 2 clock cycles.
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• 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, the Analog Comparator interrupt request is enabled. When written logic
zero, the interrupt request is disabled.
• Bit 2 – ACIC: Analog Comparator Input Capture Enable
When set, this bit enables the input capture function in Timer/Counter0 to be triggered by the analog comparator.
In this case, the comparator output is directly connected to the input capture front-end logic, using the noise canceler and edge select features of the Timer/Counter0 input capture interrupt. To make the comparator trigger the
Timer/Counter0 input capture interrupt, the ICIE0 bit in “TIMSK0 – Timer/Counter Interrupt Mask Register 0” must
be set.
When this bit is cleared, no connection between the analog comparator and the input capture function exists.
• 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 12-1.
Table 12-1.
Selecting Source for Analog Comparator Interrupt.
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 “ACSR – Analog Comparator Control and Status Register”. Otherwise an interrupt can occur when
the bits are changed.
12.1.2
DIDR0 – Digital Input Disable Register 0
Bit
7
6
5
4
3
2
1
0
0x17
–
–
–
–
ADC3D
ADC2D
ADC1D
ADC0D
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
DIDR0
• Bits 1:0 – ADC1D, ADC0D: Digital Input Disable
When this bit is set, the digital input buffer on pin AIN1 (ADC1) / AIN0 (ADC0) is disabled and the corresponding
PIN register bit will read as zero. When used as an analog input but not required as a digital input the power consumption in the digital input buffer can be reduced by writing this bit to logic one.
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13. Analog to Digital Converter
13.1
Features
•
•
•
•
•
•
•
•
•
•
•
•
13.2
8-bit Resolution
0.5 LSB Integral Non-linearity
± 1 LSB Absolute Accuracy
65µs Conversion Time
15 kSPS at Full Resolution
Four Multiplexed Single Ended Input Channels
Input Voltage Range: 0 – VCC
Supply Voltage Range: 2.5V – 5.5V
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
ATtiny5/10 feature an 8-bit, successive approximation ADC. 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. A block diagram of the ADC is shown in Figure 13-1 on page 83.
Internal reference voltage of VCC is provided on-chip.
The ADC is not available in ATtiny4/9.
13.3
Operation
In order to be able to use the ADC the Power Reduction bit, PRADC, in the Power Reduction Register must be disabled. This is done by clearing the PRADC bit. See “PRR – Power Reduction Register” on page 26 for more
details.
The ADC is enabled by setting the ADC Enable bit, ADEN in “ADCSRA – ADC Control and Status Register A”.
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 converts an analog input voltage to an 8-bit digital value using successive approximation. The minimum
value represents GND and the maximum value represents the voltage on VCC.
The analog input channel is selected by writing MUX1:0 bits. See “ADMUX – ADC Multiplexer Selection Register”
on page 92. Any of the ADC input pins can be selected as single ended inputs to the ADC.
The ADC generates an 8-bit result which is presented in the ADC data register. See “ADCL – ADC Data Register”
on page 94.
The ADC has its own interrupt request which can be triggered when a conversion completes.
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Figure 13-1. Analog to Digital Converter Block Schematic
ADCSRB
ADCL
ADIE
ADEN
ADPS0
ADPS1
ADPS2
ADSC
ADATE
ADCSRA
ADTS2:0
ADC IRQ
TRIGGER
SELECT
PRESCALER
ADIF
CHANNEL
START
DECODER
ADC7:0
MUX1
MUX0
ADMUX
INTERRUPT FLAGS
8-BIT DATA BUS
CONVERSION LOGIC
VREF
VCC
8-BIT DAC
+
ADC3
ADC2
ADC1
INPUT
MUX
SAMPLE & HOLD
COMPARATOR
ADC0
13.4
Starting a Conversion
Make sure the ADC is powered by clearing the ADC Power Reduction bit, PRADC, in the Power Reduction Register, PRR (see “PRR – Power Reduction Register” on page 26).
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 – ADC Control and Status Register B”. See Table 13-4 on page 93 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. 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 13-2. ADC Auto Trigger Logic
ADTS[2:0]
PRESCALER
CLKADC
START
ADIF
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 bit 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.
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.
Figure 13-3. ADC Prescaler
ADEN
START
Reset
7-BIT ADC PRESCALER
CK/64
CK/128
CK/32
CK/8
CK/16
CK/4
CK
CK/2
13.5
ADPS0
ADPS1
ADPS2
ADC CLOCK SOURCE
The ADC module contains a prescaler, as illustrated in Figure 13-3 on page 84, which generates an acceptable
ADC clock frequency from any CPU frequency above 100 kHz. The prescaling is set by the ADPS bits in ADCSRA.
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.
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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, as summarised in Table 13-1 on page 86. 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. See Figure 13-4.
Figure 13-4. ADC Timing Diagram, First Conversion (Single Conversion Mode)
Next
Conversion
First Conversion
Cycle Number
1
2
12
13
14
16
15
17
18
19
20
21
22
23
24
25
1
2
3
ADC Clock
ADEN
ADSC
ADIF
Conversion Result
ADCL
MUX
Update
Conversion MUX
Complete Update
Sample & Hold
The actual sample-and-hold takes place 3 ADC clock cycles after the start of a normal conversion and 16 ADC
clock cycles after the start of a first conversion. See Figure 13-5. 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 13-5. 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
ADCL
Conversion Result
MUX
Update
Sample & Hold
Conversion MUX
Complete Update
When Auto Triggering is used, the prescaler is reset when the trigger event occurs. See Figure 13-6. 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.
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Figure 13-6. 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
ADCL
Conversion Result
Prescaler MUX
Reset Update
Conversion Prescaler
Reset
Complete
Sample &
Hold
In Free Running mode (see Figure 13-7), a new conversion will be started immediately after the conversion completes, while ADSC remains high.
Figure 13-7. ADC Timing Diagram, Free Running Conversion
One Conversion
Cycle Number
11
12
Next Conversion
13
1
2
3
4
ADC Clock
ADSC
ADIF
ADCL
Conversion Result
Conversion complete
MUX update
Sample & Hold
For a summary of conversion times, see Table 13-1.
Table 13-1.
ADC Conversion Time
Sample & Hold (Cycles
from Start of Conversion)
Conversion Time (Cycles)
First conversion
16.5
25
Normal conversions
3.5
13
4
13.5
Condition
Auto Triggered conversions
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13.6
Changing Channel
The MUXn bits in the ADMUX Register are single buffered through a temporary register to which the CPU has random access. This ensures that the channel selection only takes place at a safe point during the conversion. The
channel is continuously updated until a conversion is started. Once the conversion starts, the channel 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 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.
13.6.1
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.
13.6.2
ADC Voltage Reference
The reference voltage of the ADC determines the conversion range, which in this case is limited to 0V (VGND) and
VREF = Vcc. Channels that exceed VREF will result in codes saturated at 0xFF.
13.7
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, that interrupt will be executed, and an ADC Conversion Complete interrupt request will
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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.
13.8
Analog Input Circuitry
The analog input circuitry for single ended channels is illustrated in Figure 13-8 An analog source applied to ADCn
is subjected to the pin capacitance and input leakage of that pin, regardless of whether that channel is selected as
input for the ADC. When the channel is selected, the source must drive the S/H (sample and hold) capacitor
through the series resistance (combined resistance in the input path).
Figure 13-8. Analog Input Circuitry
IIH
ADCn
1..100 kohm
CS/H= 14 pF
IIL
VCC/2
The capacitor in Figure 13-8 depicts the total capacitance, including the sample/hold capacitor and any stray or
parasitic capacitance inside the device. The value given is worst case.
The ADC is optimized for analog signals with an output impedance of approximately 10 k, or less. With such
sources, 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. This can vary widely. The user is recommended to only use low impedance 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.
13.9
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.
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Where high ADC accuracy is required it is recommended to use ADC Noise Reduction Mode, as described in Section 13.7 on page 87. A good system design with properly placed, external bypass capacitors does reduce the
need for using ADC Noise Reduction Mode
13.10 ADC Accuracy Definitions
An n-bit single-ended ADC converts a voltage linearly between GND and VREF in 2n 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:
• Offset: The deviation of the first transition (0x00 to 0x01) compared to the ideal transition (at 0.5 LSB). Ideal
value: 0 LSB.
Figure 13-9. Offset Error
Output Code
Ideal ADC
Actual ADC
Offset
Error
VREF Input Voltage
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• Gain Error: After adjusting for offset, the Gain Error is found as the deviation of the last transition (0xFE to 0xFF)
compared to the ideal transition (at 1.5 LSB below maximum). Ideal value: 0 LSB
Figure 13-10. Gain Error
Gain
Error
Output Code
Ideal ADC
Actual ADC
VREF Input Voltage
• 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 13-11. 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.
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Figure 13-12. Differential Non-linearity (DNL)
Output Code
0xFF
1 LSB
DNL
0x00
0
VREF
Input Voltage
• 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.
13.11 ADC Conversion Result
After the conversion is complete (ADIF is high), the conversion result can be found in the ADC Data Register
(ADCL). For single ended conversion, the result is
V IN  256
ADCL = ----------------------V CC
where VIN (see Table 13-2 on page 92) is the voltage on the selected input pin and VCC is the voltage reference.
0x00 represents analog ground, and 0xFF represents the selected reference voltage minus one LSB.
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13.12 Register Description
13.12.1
ADMUX – ADC Multiplexer Selection Register
Bit
7
6
5
4
3
2
1
0
0x1B
–
–
–
–
–
–
MUX1
MUX0
Read/Write
R
R
R
R
R
R
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
ADMUX
• Bits 7:2 – Res: Reserved Bits
These bits are reserved and will always read 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 13-2 for
details..
Table 13-2.
Input Channel Selections
MUX1
MUX0
Single Ended Input
Pin
0
ADC0
PB0
1
ADC1
PB1
0
ADC2
PB2
1
ADC3
PB3
0
1
If these bits are changed during a conversion, the change will not go in effect until the conversion is complete
(ADIF in ADCSRA is set)
13.12.2
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
0x1D
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.
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• 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 requested if the ADIE bit is 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.
• Bit 3 – ADIE: ADC Interrupt Enable
When this bit is written to one, the ADC Conversion Complete Interrupt request is enabled.
• 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 13-3.
13.12.3
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
ADCSRB – ADC Control and Status Register B
Bit
7
6
5
4
3
2
1
0
0x1C
–
–
–
–
–
ADTS2
ADTS1
ADTS0
Read/Write
R
R
R
R
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
ADCSRB
• Bits 7:3 – Res: Reserved Bits
These bits are reserved and will always read 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 13-4.
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 Flag 0
0
1
1
Timer/Counter 0 Compare Match A
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Table 13-4.
13.12.4
ADC Auto Trigger Source Selections
ADTS2
ADTS1
ADTS0
Trigger Source
1
0
0
Timer/Counter 0 Overflow
1
0
1
Timer/Counter 0 Compare Match B
1
1
0
Pin Change Interrupt 0 Request
1
1
1
Timer/Counter 0 Capture Event
ADCL – ADC Data Register
Bit
7
6
5
4
3
2
1
0
ADC7
ADC6
ADC5
ADC4
ADC3
ADC2
ADC1
ADC0
Read/Write
R
R
R
R
R
R
R
R
Initial Value
0
0
0
0
0
0
0
0
0x19
ADCL
When an ADC conversion is complete, the result is found in the ADC register.
• Bits 7:0 – ADC7:0: ADC Conversion Result
These bits represent the result from the conversion.
13.12.5
DIDR0 – Digital Input Disable Register 0
Bit
7
6
5
4
3
2
1
0
0x17
–
–
–
–
ADC3D
ADC2D
ADC1D
ADC0D
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
DIDR0
• Bits 7:4 – Res: Reserved Bit
These bits are reserved and will always read zero.
• Bits 3:0 – ADC3D..ADC0D: ADC3..0 Digital Input Disable
When this 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
ADC3..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. Programming interface
14.1
Features
• Physical Layer:
– Synchronous Data Transfer
– Bi-directional, Half-duplex Receiver And Transmitter
– Fixed Frame Format With One Start Bit, 8 Data Bits, One Parity Bit And 2 Stop Bits
– Parity Error Detection, Frame Error Detection And Break Character Detection
– Parity Generation And Collision Detection
– Automatic Guard Time Insertion Between Data Reception And Transmission
• Access Layer:
– Communication Based On Messages
– Automatic Exception Handling Mechanism
– Compact Instruction Set
– NVM Programming Access Control
– Tiny Programming Interface Control And Status Space Access Control
– Data Space Access Control
14.2
Overview
The Tiny Programming Interface (TPI) supports external programming of all Non-Volatile Memories (NVM). Memory programming is done via the NVM Controller, by executing NVM controller commands as described in “Memory
Programming” on page 106.
The Tiny Programming Interface (TPI) provides access to the programming facilities. The interface consists of two
layers: the access layer and the physical layer. The layers are illustrated in Figure 14-1.
Figure 14-1. The Tiny Programming Interface and Related Internal Interfaces
TINY PROGRAMMING INTERFACE (TPI)
RESET
TPICLK
TPIDATA
PHYSICAL
LAYER
ACCESS
LAYER
NVM
CONTROLLER
NON-VOLATILE
MEMORIES
DATA BUS
Programming is done via the physical interface. This is a 3-pin interface, which uses the RESET pin as enable, the
TPICLK pin as the clock input, and the TPIDATA pin as data input and output.
NVM can be programmed at 5V, only.
14.3
Physical Layer of Tiny Programming Interface
The TPI physical layer handles the basic low-level serial communication. The TPI physical layer uses a bi-directional, half-duplex serial receiver and transmitter. The physical layer includes serial-to-parallel and parallel-to-serial
data conversion, start-of-frame detection, frame error detection, parity error detection, parity generation and collision detection.
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The TPI is accessed via three pins, as follows:
RESET:
TPICLK:
TPIDATA:
Tiny Programming Interface enable input
Tiny Programming Interface clock input
Tiny Programming Interface data input/output
In addition, the VCC and GND pins must be connected between the external programmer and the device. See Figure 14-2.
Figure 14-2. Using an External Programmer for In-System Programming via TPI
+5V
ATtiny4/5/9/10
TPI
CONN
TPIDATA/PB0
PB3/RESET
GND
VCC
TPICLK/PB1
PB2
APPLICATION
NVM can be programmed at 5V, only. In some designs it may be necessary to protect components that can not tolerate 5V with, for example, series resistors.
14.3.1
Enabling
The following sequence enables the Tiny Programming Interface (see Figure 14-3 for guidance):
• Apply 5V between VCC and GND
• Depending on the method of reset to be used:
– Either: wait tTOUT (see Table 16-4 on page 118) and then set the RESET pin low. This will reset the
device and enable the TPI physical layer. The RESET pin must then be kept low for the entire
programming session
– Or: if the RSTDISBL configuration bit has been programmed, apply 12V to the RESET pin. The RESET
pin must be kept at 12V for the entire programming session
• Wait tRST (see Table 16-4 on page 118)
• Keep the TPIDATA pin high for 16 TPICLK cycles
Figure 14-3. Sequence for enabling the Tiny Programming Interface
t
RST
16 x TPICLK CYCLES
RESET
TPICLK
TPIDATA
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14.3.2
Disabling
Provided that the NVM enable bit has been cleared, the TPI is automatically disabled if the RESET pin is released
to inactive high state or, alternatively, if VHV is no longer applied to the RESET pin.
If the NVM enable bit is not cleared a power down is required to exit TPI programming mode.
See NVMEN bit in “TPISR – Tiny Programming Interface Status Register” on page 105.
14.3.3
Frame Format
The TPI physical layer supports a fixed frame format. A frame consists of one character, eight bits in length, and
one start bit, a parity bit and two stop bits. Data is transferred with the least significant bit first.
Figure 14-4. Serial frame format.
TPICLK
TPIDATA
IDLE
ST
D0
D1
D7
P
SP1
SP2
IDLE/ST
Symbols used in Figure 14-4:
ST:
D0-D7:
P:
SP1:
SP2:
14.3.4
Start bit (always low)
Data bits (least significant bit sent first)
Parity bit (using even parity)
Stop bit 1 (always high)
Stop bit 2 (always high)
Parity Bit Calculation
The parity bit is always calculated using even parity. The value of the bit is calculated by doing an exclusive-or of
all the data bits, as follows:
P = D0  D1  D2  D3  D4  D5  D6  D7  0
where:
P:
D0-D7:
14.3.5
Parity bit using even parity
Data bits of the character
Supported Characters
The BREAK character is equal to a 12 bit long low level. It can be extended beyond a bit-length of 12.
Figure 14-5. Supported characters.
DATA CHARACTER
TPIDATA
IDLE
ST
D0
D1
D7
P
SP1
SP2
IDLE/ST
BREAK CHARACTER
TPIDATA
14.3.6
IDLE
IDLE/ST
Operation
The TPI physical layer operates synchronously on the TPICLK provided by the external programmer. The dependency between the clock edges and data sampling or data change is shown in Figure 14-6. Data is changed at
falling edges and sampled at rising edges.
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Figure 14-6. Data changing and Data sampling.
TPICLK
TPIDATA
SAMPLE
SETUP
The TPI physical layer supports two modes of operation: Transmit and Receive. By default, the layer is in Receive
mode, waiting for a start bit. The mode of operation is controlled by the access layer.
14.3.7
Serial Data Reception
When the TPI physical layer is in receive mode, data reception is started as soon as a start bit has been detected.
Each bit that follows the start bit will be sampled at the rising edge of the TPICLK and shifted into the shift register
until the second stop bit has been received. When the complete frame is present in the shift register the received
data will be available for the TPI access layer.
There are three possible exceptions in the receive mode: frame error, parity error and break detection. All these
exceptions are signalized to the TPI access layer, which then enters the error state and puts the TPI physical layer
into receive mode, waiting for a BREAK character.
• Frame Error Exception. The frame error exception indicates the state of the stop bit. The frame error exception
is set if the stop bit was read as zero.
• Parity Error Exception. The parity of the data bits is calculated during the frame reception. After the frame is
received completely, the result is compared with the parity bit of the frame. If the comparison fails the parity
error exception is signalized.
• Break Detection Exception. The Break detection exception is given when a complete frame of all zeros has
been received.
14.3.8
Serial Data Transmission
When the TPI physical layer is ready to send a new frame it initiates data transmission by loading the shift register
with the data to be transmitted. When the shift register has been loaded with new data, the transmitter shifts one
complete frame out on the TPIDATA line at the transfer rate given by TPICLK.
If a collision is detected during transmission, the output driver is disabled. The TPI access layer enters the error
state and the TPI physical layer is put into receive mode, waiting for a BREAK character.
14.3.9
Collision Detection Exception
The TPI physical layer uses one bi-directional data line for both data reception and transmission. A possible drive
contention may occur, if the external programmer and the TPI physical layer drive the TPIDATA line simultaneously. In order to reduce the effect of the drive contention, a collision detection mechanism is supported. The
collision detection is based on the way the TPI physical layer drives the TPIDATA line.
The TPIDATA line is driven by a tri-state, push-pull driver with internal pull-up. The output driver is always enabled
when a logical zero is sent. When sending successive logical ones, the output is only driven actively during the first
clock cycle. After this, the output driver is automatically tri-stated and the TPIDATA line is kept high by the internal
pull-up. The output is re-enabled, when the next logical zero is sent.
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The collision detection is enabled in transmit mode, when the output driver has been disabled. The data line should
now be kept high by the internal pull-up and it is monitored to see, if it is driven low by the external programmer. If
the output is read low, a collision has been detected.
There are some potential pit-falls related to the way collision detection is performed. For example, collisions cannot
be detected when the TPI physical layer transmits a bit-stream of successive logical zeros, or bit-stream of alternating logical ones and zeros. This is because the output driver is active all the time, preventing polling of the
TPIDATA line. However, within a single frame the two stop bits should always be transmitted as logical ones,
enabling collision detection at least once per frame (as long as the frame format is not violated regarding the stop
bits).
The TPI physical layer will cease transmission when it detects a collision on the TPIDATA line. The collision is signalized to the TPI access layer, which immediately changes the physical layer to receive mode and goes to the
error state. The TPI access layer can be recovered from the error state only by sending a BREAK character.
14.3.10
Direction Change
In order to ensure correct timing of the half-duplex operation, a simple guard time mechanism has been added to
the physical layer. When the TPI physical layer changes from receive to transmit mode, a configurable number of
additional IDLE bits are inserted before the start bit is transmitted. The minimum transition time between receive
and transmit mode is two IDLE bits. The total IDLE time is the specified guard time plus two IDLE bits.
The guard time is configured by dedicated bits in the TPIPCR register. The default guard time value after the physical layer is initialized is 128 bits.
The external programmer looses control of the TPIDATA line when the TPI target changes from receive mode to
transmit. The guard time feature relaxes this critical phase of the communication. When the external programmer
changes from receive mode to transmit, a minimum of one IDLE bit should be inserted before the start bit is
transmitted.
14.4
Access Layer of Tiny Programming Interface
The TPI access layer is responsible for handling the communication with the external programmer. The communication is based on message format, where each message comprises an instruction followed by one or more bytesized operands. The instruction is always sent by the external programmer but operands are sent either by the
external programmer or by the TPI access layer, depending on the type of instruction issued.
The TPI access layer controls the character transfer direction on the TPI physical layer. It also handles the recovery from the error state after exception.
The Control and Status Space (CSS) of the Tiny Programming Interface is allocated for control and status registers
in the TPI access Layer. The CSS consist of registers directly involved in the operation of the TPI itself. These register are accessible using the SLDCS and SSTCS instructions.
The access layer can also access the data space, either directly or indirectly using the Pointer Register (PR) as the
address pointer. The data space is accessible using the SLD, SST, SIN and SOUT instructions. The address
pointer can be stored in the Pointer Register using the SLDPR instruction.
14.4.1
Message format
Each message comprises an instruction followed by one or more byte operands. The instruction is always sent by
the external programmer. Depending on the instruction all the following operands are sent either by the external
programmer or by the TPI.
The messages can be categorized in two types based on the instruction, as follows:
• Write messages. A write message is a request to write data. The write message is sent entirely by the external
programmer. This message type is used with the SSTCS, SST, STPR, SOUT and SKEY instructions.
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• Read messages. A read message is a request to read data. The TPI reacts to the request by sending the byte
operands. This message type is used with the SLDCS, SLD and SIN instructions.
All the instructions except the SKEY instruction require the instruction to be followed by one byte operand. The
SKEY instruction requires 8 byte operands. For more information, see the TPI instruction set on page 100.
14.4.2
Exception Handling and Synchronisation
Several situations are considered exceptions from normal operation of the TPI. When the TPI physical layer is in
receive mode, these exceptions are:
• The TPI physical layer detects a parity error.
• The TPI physical layer detects a frame error.
• The TPI physical layer recognizes a BREAK character.
When the TPI physical layer is in transmit mode, the possible exceptions are:
• The TPI physical layer detects a data collision.
All these exceptions are signalized to the TPI access layer. The access layer responds to an exception by aborting
any on-going operation and enters the error state. The access layer will stay in the error state until a BREAK character has been received, after which it is taken back to its default state. As a consequence, the external
programmer can always synchronize the protocol by simply transmitting two successive BREAK characters.
14.5
Instruction Set
The TPI has a compact instruction set that is used to access the TPI Control and Status Space (CSS) and the data
space. The instructions allow the external programmer to access the TPI, the NVM Controller and the NVM memories. All instructions except SKEY require one byte operand following the instruction. The SKEY instruction is
followed by 8 data bytes. All instructions are byte-sized.
The TPI instruction set is summarised in Table 14-1.
Table 14-1.
Instruction Set Summary
Mnemonic
Operand
Description
Operation
SLD
data, PR
Serial LoaD from data space using indirect
addressing
data  DS[PR]
SLD
data, PR+
Serial LoaD from data space using indirect
addressing and post-increment
data  DS[PR]
PR  PR+1
SST
PR, data
Serial STore to data space using indirect
addressing
DS[PR]  data
SST
PR+, data
Serial STore to data space using indirect
addressing and post-increment
DS[PR]  data
PR  PR+1
SSTPR
PR, a
Serial STore to Pointer Register using direct
addressing
PR[a]  data
SIN
data, a
Serial IN from data space
data  I/O[a]
SOUT
a, data
Serial OUT to data space
I/O[a]  data
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Table 14-1.
14.5.1
Mnemonic
Operand
Description
Operation
SLDCS
data, a
Serial LoaD from Control and Status space
using direct addressing
data  CSS[a]
SSTCS
a, data
Serial STore to Control and Status space
using direct addressing
CSS[a]  data
SKEY
Key, {8{data}}
Serial KEY
Key  {8{data}}
SLD - Serial LoaD from data space using indirect addressing
The SLD instruction uses indirect addressing to load data from the data space to the TPI physical layer shift-register for serial read-out. The data space location is pointed by the Pointer Register (PR), where the address must
have been stored before data is accessed. The Pointer Register is either left unchanged by the operation, or postincremented, as shown in Table 14-2.
Table 14-2.
14.5.2
The Serial Load from Data Space (SLD) Instruction
Operation
Opcode
Remarks
Register
data  DS[PR]
0010 0000
PR  PR
Unchanged
data  DS[PR]
0010 0100
PR  PR + 1
Post increment
SST - Serial STore to data space using indirect addressing
The SST instruction uses indirect addressing to store into data space the byte that is shifted into the physical layer
shift register. The data space location is pointed by the Pointer Register (PR), where the address must have been
stored before the operation. The Pointer Register can be either left unchanged by the operation, or it can be postincremented, as shown in Table 14-3.
Table 14-3.
14.5.3
Instruction Set Summary (Continued)
The Serial Store to Data Space (SLD) Instruction
Operation
Opcode
Remarks
Register
DS[PR] data
0110 0000
PR  PR
Unchanged
DS[PR] data
0110 0100
PR  PR + 1
Post increment
SSTPR - Serial STore to Pointer Register
The SSTPR instruction stores the data byte that is shifted into the physical layer shift register to the Pointer Register (PR). The address bit of the instruction specifies which byte of the Pointer Register is accessed, as shown in
Table 14-4.
Table 14-4.
The Serial Store to Pointer Register (SSTPR) Instruction
Operation
Opcode
Remarks
PR[a] data
0110 100a
Bit ‘a’ addresses Pointer Register byte
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14.5.4
SIN - Serial IN from i/o space using direct addressing
The SIN instruction loads data byte from the I/O space to the shift register of the physical layer for serial read-out.
The instuction uses direct addressing, the address consisting of the 6 address bits of the instruction, as shown in
Table 14-5.
Table 14-5.
14.5.5
Operation
Opcode
Remarks
data I/O[a]
0aa1 aaaa
Bits marked ‘a’ form the direct, 6-bit addres
SOUT - Serial OUT to i/o space using direct addressing
The SOUT instruction stores the data byte that is shifted into the physical layer shift register to the I/O space. The
instruction uses direct addressing, the address consisting of the 6 address bits of the instruction, as shown in Table
14-6.
Table 14-6.
14.5.6
The Serial OUT to i/o space (SOUT) Instruction
Operation
Opcode
Remarks
I/O[a] data
1aa1 aaaa
Bits marked ‘a’ form the direct, 6-bit addres
SLDCS - Serial LoaD data from Control and Status space using direct addressing
The SLDCS instruction loads data byte from the TPI Control and Status Space to the TPI physical layer shift register for serial read-out. The SLDCS instruction uses direct addressing, the direct address consisting of the 4
address bits of the instruction, as shown in Table 14-7.
Table 14-7.
14.5.7
The Serial IN from i/o space (SIN) Instruction
The Serial Load Data from Control and Status space (SLDCS) Instruction
Operation
Opcode
Remarks
data CSS[a]
1000 aaaa
Bits marked ‘a’ form the direct, 4-bit addres
SSTCS - Serial STore data to Control and Status space using direct addressing
The SSTCS instruction stores the data byte that is shifted into the TPI physical layer shift register to the TPI Control
and Status Space. The SSTCS instruction uses direct addressing, the direct address consisting of the 4 address
bits of the instruction, as shown in Table 14-8.
Table 14-8.
The Serial STore data to Control and Status space (SSTCS) Instruction
Operation
Opcode
Remarks
CSS[a] data
1100 aaaa
Bits marked ‘a’ form the direct, 4-bit addres
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14.5.8
SKEY - Serial KEY signaling
The SKEY instruction is used to signal the activation key that enables NVM programming. The SKEY instruction is
followed by the 8 data bytes that includes the activation key, as shown in Table 14-9.
Table 14-9.
14.6
The Serial KEY signaling (SKEY) Instruction
Operation
Opcode
Remarks
Key {8[data}}
1110 0000
Data bytes follow after instruction
Accessing the Non-Volatile Memory Controller
By default, NVM programming is not enabled. In order to access the NVM Controller and be able to program the
non-volatile memories, a unique key must be sent using the SKEY instruction. The 64-bit key that will enable NVM
programming is given in Table 14-10.
Table 14-10. Enable Key for Non-Volatile Memory Programming
Key
Value
NVM Program Enable
0x1289AB45CDD888FF
After the key has been given, the Non-Volatile Memory Enable (NVMEN) bit in the TPI Status Register (TPISR)
must be polled until the Non-Volatile memory has been enabled.
NVM programming is disabled by writing a logical zero to the NVMEN bit in TPISR.
14.7
Control and Status Space Register Descriptions
The control and status registers of the Tiny Programming Interface are mapped in the Control and Status Space
(CSS) of the interface. These registers are not part of the I/O register map and are accessible via SLDCS and
SSTCS instructions, only. The control and status registers are directly involved in configuration and status monitoring of the TPI.
A summary of CSS registers is shown in Table 14-11.
Table 14-11. Summary of Control and Status Registers
Addr.
Name
0x0F
TPIIR
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Tiny Programming Interface Identification Code
0x0E
Reserved
–
–
–
–
–
–
–
–
0x02
TPIPCR
–
–
–
–
–
GT2
GT1
GT0
0x01
Reserved
–
–
–
–
–
–
–
–
0x00
TPISR
–
–
–
–
–
–
NVMEN
–
...
0x03
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14.7.1
TPIIR – Tiny Programming Interface Identification Register
Bit
7
6
5
CSS: 0x0F
4
3
2
1
0
Programming Interface Identification Code
TPIIR
Read/Write
R
R
R
R
R
R
R
R
Initial Value
0
0
0
0
0
0
0
0
• Bits 7:0 – TPIIC: Tiny Programming Interface Identification Code
These bits give the identification code for the Tiny Programming Interface. The code can be used be the external
programmer to identify the TPI. The identification code of the Tiny Programming Interface is shown in Table 14-12..
Table 14-12. Identification Code for Tiny Programming Interface
14.7.2
Code
Value
Interface Identification
0x80
TPIPCR – Tiny Programming Interface Physical Layer Control Register
Bit
7
6
5
4
3
2
1
0
CSS: 0x02
–
–
–
–
–
GT2
GT1
GT0
Read/Write
R
R
R
R
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
TPIPCR
• Bits 7:3 – Res: Reserved Bits
These bits are reserved and will always read zero.
• Bits 2:0 – GT[2:0]: Guard Time
These bits specify the number of additional IDLE bits that are inserted to the idle time when changing from reception mode to transmission mode. Additional delays are not inserted when changing from transmission mode to
reception.
The total idle time when changing from reception to transmission mode is Guard Time plus two IDLE bits. Table
14-13 shows the available Guard Time settings.
Table 14-13. Guard Time Settings
GT2
GT1
GT0
Guard Time (Number of IDLE bits)
0
0
0
+128 (default value)
0
0
1
+64
0
1
0
+32
0
1
1
+16
1
0
0
+8
1
0
1
+4
1
1
0
+2
1
1
1
+0
The default Guard Time is 128 IDLE bits. To speed up the communication, the Guard Time should be set to the
shortest safe value.
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14.7.3
TPISR – Tiny Programming Interface Status Register
Bit
7
6
5
4
3
2
1
CSS: 0x00
–
–
–
–
–
–
NVMEN
0
–
Read/Write
R
R
R
R
R
R
R/W
R
Initial Value
0
0
0
0
0
0
0
0
TPIPCR
• Bits 7:2, 0 – Res: Reserved Bits
These bits are reserved and will always read zero.
• Bit 1 – NVMEN: Non-Volatile Memory Programming Enabled
NVM programming is enabled when this bit is set. The external programmer can poll this bit to verify the interface
has been successfully enabled.
NVM programming is disabled by writing this bit to zero.
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15. Memory Programming
15.1
Features
• Two Embedded Non-Volatile Memories:
•
•
•
•
•
15.2
– Non-Volatile Memory Lock bits (NVM Lock bits)
– Flash Memory
Four Separate Sections Inside Flash Memory:
– Code Section (Program Memory)
– Signature Section
– Configuration Section
– Calibration Section
Read Access to All Non-Volatile Memories from Application Software
Read and Write Access to Non-Volatile Memories from External programmer:
– Read Access to All Non-Volatile Memories
– Write Access to NVM Lock Bits, Flash Code Section and Flash Configuration Section
External Programming:
– Support for In-System and Mass Production Programming
– Programming Through the Tiny Programming Interface (TPI)
High Security with NVM Lock Bits
Overview
The Non-Volatile Memory (NVM) Controller manages all access to the Non-Volatile Memories. The NVM Controller
controls all NVM timing and access privileges, and holds the status of the NVM.
During normal execution the CPU will execute code from the code section of the Flash memory (program memory).
When entering sleep and no programming operations are active, the Flash memory is disabled to minimize power
consumption.
All NVM are mapped to the data memory. Application software can read the NVM from the mapped locations of
data memory using load instruction with indirect addressing.
The NVM has only one read port and, therefore, the next instruction and the data can not be read simultaneously.
When the application reads data from NVM locations mapped to the data space, the data is read first before the
next instruction is fetched. The CPU execution is here delayed by one system clock cycle.
Internal programming operations to NVM have been disabled and the NVM therefore appears to the application
software as read-only. Internal write or erase operations of the NVM will not be successful.
The method used by the external programmer for writing the Non-Volatile Memories is referred to as external programming. External programming can be done both in-system or in mass production. See Figure 14-2 on page 96.
The external programmer can read and program the NVM via the Tiny Programming Interface (TPI).
In the external programming mode all NVM can be read and programmed, except the signature and the calibration
sections which are read-only.
NVM can be programmed at 5V, only.
15.3
Non-Volatile Memories
The ATtiny4/5/9/10 have the following, embedded NVM:
• Non-Volatile Memory Lock Bits
• Flash memory with four separate sections
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15.3.1
Non-Volatile Memory Lock Bits
The ATtiny4/5/9/10 provide two Lock Bits, as shown in Table 15-1.
Table 15-1.
Lock Bit Byte
Lock Bit
Bit No
Description
Default Value
7
1 (unprogrammed)
6
1 (unprogrammed)
5
1 (unprogrammed)
4
1 (unprogrammed)
3
1 (unprogrammed)
2
1 (unprogrammed)
NVLB2
1
Non-Volatile Lock Bit
1 (unprogrammed)
NVLB1
0
Non-Volatile Lock Bit
1 (unprogrammed)
The Lock Bits can be left unprogrammed ("1") or can be programmed ("0") to obtain the additional security shown
in Table 15-2. Lock Bits can be erased to "1" with the Chip Erase command, only.
Table 15-2.
Lock Bit Protection Modes
Memory Lock Bits (1)
Lock Mode
NVLB2 (2)
NVLB1 (2)
1
1
1
No Memory Lock feature Enabled
0
Further Programming of the Flash memory is disabled in
the external programming mode. The configuration
section bits are locked in the external programming
mode
0
Further programming and verification of the flash is
disabled in the external programming mode. The
configuration section bits are locked in the external
programming mode
2
1
3
Notes:
0
Protection Type
1. Program the configuration section bits before programming NVLB1 and NVLB2.
2. "1" means unprogrammed, "0" means programmed
15.3.2
Flash Memory
The embedded Flash memory of ATtiny4/5/9/10 has four separate sections, as shown in Table 15-3 and Table 153.
Table 15-3.
Number of Words and Pages in the Flash (ATtiny9/10)
Section
Code (program memory)
Configuration
Signature
(1)
Calibration
(1)
Size (Bytes)
Page Size (Words)
Pages
WADDR
PADDR
1024
8
64
[3:1]
[9:4]
8
8
1
[3:1]
–
16
8
2
[3:1]
[4:4]
8
8
1
[3:1]
–
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Notes:
1. This section is read-only.
Table 15-4.
Number of Words and Pages in the Flash (ATtiny4/5)
Section
Size (Bytes)
Page Size (Words)
Pages
WADDR
PADDR
512
8
32
[3:1]
[9:4]
8
8
1
[3:1]
–
16
8
2
[3:1]
[4:4]
8
8
1
[3:1]
–
Code (program memory)
Configuration
Signature
(1)
Calibration (1)
Notes:
15.3.3
1. This section is read-only.
Configuration Section
ATtiny4/5/9/10 have one configuration byte, which resides in the configuration section. See Table 15-5.
Table 15-5.
Configuration bytes
Configuration word data
Configuration word address
High byte
Low byte
0x00
Reserved
Configuration Byte 0
0x01 ... 0x07
Reserved
Reserved
Table 15-6 briefly describes the functionality of all configuration bits and how they are mapped into the configuration byte.
Table 15-6.
Configuration Byte 0
Bit
Bit Name
Description
Default Value
7:3
–
Reserved
1 (unprogrammed)
2
CKOUT
System Clock Output
1 (unprogrammed)
1
WDTON
Watchdog Timer always on
1 (unprogrammed)
0
RSTDISBL
External Reset disable
1 (unprogrammed)
Configuration bits are not affected by a chip erase but they can be cleared using the configuration section erase
command (see “Erasing the Configuration Section” on page 112). Note that configuration bits are locked if NonVolatile Lock Bit 1 (NVLB1) is programmed.
15.3.3.1
Latching of Configuration Bits
All configuration bits are latched either when the device is reset or when the device exits the external programming
mode. Changes to configuration bit values have no effect until the device leaves the external programming mode.
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15.3.4
Signature Section
The signature section is a dedicated memory area used for storing miscellaneous device information, such as the
device signature. Most of this memory section is reserved for internal use, as shown in Table 15-7.
Table 15-7.
Signature bytes
Signature word data
Signature word address
High byte
Low byte
0x00
Device ID 1
Manufacturer ID
0x01
Reserved for internal use
Device ID 2
0x02 ... 0x0F
Reserved for internal use
Reserved for internal use
ATtiny4/5/9/10 have a three-byte signature code, which can be used to identify the device. The three bytes reside
in the signature section, as shown in Table 15-7. The signature data for ATtiny4/5/9/10 is given in Table 15-8.
Table 15-8.
Signature codes
Signature Bytes
Part
15.3.5
Manufacturer ID
Device ID 1
Device ID 2
ATtiny4
0x1E
0x8F
0x0A
ATtiny5
0x1E
0x8F
0x09
ATtiny9
0x1E
0x90
0x08
ATtiny10
0x1E
0x90
0x03
Calibration Section
ATtiny4/5/9/10 have one calibration byte. The calibration byte contains the calibration data for the internal oscillator
and resides in the calibration section, as shown in Table 15-9. During reset, the calibration byte is automatically
written into the OSCCAL register to ensure correct frequency of the calibrated internal oscillator.
Table 15-9.
Calibration byte
Calibration word data
Calibration word address
High byte
Low byte
0x00
Reserved
Internal oscillator calibration value
0x01 ... 0x07
Reserved
Reserved
15.3.5.1
Latching of Calibration Value
To ensure correct frequency of the calibrated internal oscillator the calibration value is automatically written into the
OSCCAL register during reset.
15.4
Accessing the NVM
NVM lock bits, and all Flash memory sections are mapped to the data space as shown in Figure 5-1 on page 15.
The NVM can be accessed for read and programming via the locations mapped in the data space.
The NVM Controller recognises a set of commands that can be used to instruct the controller what type of programming task to perform on the NVM. Commands to the NVM Controller are issued via the NVM Command
Register. See “NVMCMD - Non-Volatile Memory Command Register” on page 114. After the selected command
has been loaded, the operation is started by writing data to the NVM locations mapped to the data space.
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When the NVM Controller is busy performing an operation it will signal this via the NVM Busy Flag in the NVM Control and Status Register. See “NVMCSR - Non-Volatile Memory Control and Status Register” on page 114. The
NVM Command Register is blocked for write access as long as the busy flag is active. This is to ensure that the
current command is fully executed before a new command can start.
Programming any part of the NVM will automatically inhibit the following operations:
• All programming to any other part of the NVM
• All reading from any NVM location
ATtiny4/5/9/10 support only external programming. Internal programming operations to NVM have been disabled,
which means any internal attempt to write or erase NVM locations will fail.
15.4.1
Addressing the Flash
The data space uses byte accessing but since the Flash sections are accessed as words and organized in pages,
the byte-address of the data space must be converted to the word-address of the Flash section. This is illustrated
in Figure 15-1. Also, see Table 15-3 on page 107.
The most significant bits of the data space address select the NVM Lock bits or the Flash section mapped to the
data memory. The word address within a page (WADDR) is held by bits [WADDRMSB:1], and the page address
(PADDR) by bits [PADDRMSB:WADDRMSB+1]. Together, PADDR and WADDR form the absolute address of a
word in the Flash section.
The least significant bit of the Flash section address is used to select the low or high byte of the word.
Figure 15-1. Addressing the Flash Memory
16
PADDRMSB
WADDRMSB+1 WADDRMSB
PADDR
WADDR
1
0/1
ADDRESS POINTER
LOW/HIGH
BYTE SELECT
FLASH
SECTION
FLASH
PAGE
00
00
01
01
02
...
...
...
PAGE
PAGE ADDRESS
WITHIN A FLASH
SECTION
WORD
WORD ADDRESS
WITHIN A FLASH
PAGE
...
...
...
PAGEEND
SECTIONEND
15.4.2
Reading the Flash
The Flash can be read from the data memory mapped locations one byte at a time. For read operations, the least
significant bit (bit 0) is used to select the low or high byte in the word address. If this bit is zero, the low byte is read,
and if it is one, the high byte is read.
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15.4.3
Programming the Flash
The Flash can be written word-by-word. Before writing a Flash word, the Flash target location must be erased.
Writing to an un-erased Flash word will corrupt its content.
The Flash is word-accessed for writing, and the data space uses byte-addressing to access Flash that has been
mapped to data memory. It is therefore important to write the word in the correct order to the Flash, namely low
bytes before high bytes. First, the low byte is written to the temporary buffer. Then, writing the high byte latches
both the high byte and the low byte into the Flash word buffer, starting the write operation to Flash.
The Flash erase operations can only performed for the entire Flash sections.
The Flash programming sequence is as follows:
1. Perform a Flash section erase or perform a Chip erase
2. Write the Flash section word by word
15.4.3.1
Chip Erase
The Chip Erase command will erase the entire code section of the Flash memory and the NVM Lock Bits. For
security reasons, the NVM Lock Bits are not reset before the code section has been completely erased. Configuration, Signature and Calibration sections are not changed.
Before starting the Chip erase, the NVMCMD register must be loaded with the CHIP_ERASE command. To start
the erase operation a dummy byte must be written into the high byte of a word location that resides inside the Flash
code section. The NVMBSY bit remains set until erasing has been completed. While the Flash is being erased neither Flash buffer loading nor Flash reading can be performed.
The Chip Erase can be carried out as follows:
1. Write the CHIP_ERASE command to the NVMCMD register
2. Start the erase operation by writing a dummy byte to the high byte of any word location inside the code
section
3. Wait until the NVMBSY bit has been cleared
15.4.3.2
Erasing the Code Section
The algorithm for erasing all pages of the Flash code section is as follows:
1. Write the SECTION_ERASE command to the NVMCMD register
2. Start the erase operation by writing a dummy byte to the high byte of any word location inside the code
section
3. Wait until the NVMBSY bit has been cleared
15.4.3.3
Writing a Code Word
The algorithm for writing a word to the code section is as follows:
1. Write the WORD_WRITE command to the NVMCMD register
2. Write the low byte of the data into the low byte of a word location
3. Write the high byte of the data into the high byte of the same word location. This will start the Flash write
operation
4. Wait until the NVMBSY bit has been cleared
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15.4.3.4
Erasing the Configuration Section
The algorithm for erasing the Configuration section is as follows:
1. Write the SECTION_ERASE command to the NVMCMD register
2. Start the erase operation by writing a dummy byte to the high byte of any word location inside the configuration section
3. Wait until the NVMBSY bit has been cleared
15.4.3.5
Writing a Configuration Word
The algorithm for writing a Configuration word is as follows.
1. Write the WORD_WRITE command to the NVMCMD register
2. Write the low byte of the data to the low byte of a configuration word location
3. Write the high byte of the data to the high byte of the same configuration word location. This will start the
Flash write operation.
4. Wait until the NVMBSY bit has been cleared
15.4.4
Reading NVM Lock Bits
The Non-Volatile Memory Lock Byte can be read from the mapped location in data memory.
15.4.5
Writing NVM Lock Bits
The algorithm for writing the Lock bits is as follows.
1. Write the WORD_WRITE command to the NVMCMD register.
2. Write the lock bits value to the Non-Volatile Memory Lock Byte location. This is the low byte of the NonVolatile Memory Lock Word.
3. Start the NVM Lock Bit write operation by writing a dummy byte to the high byte of the NVM Lock Word
location.
4. Wait until the NVMBSY bit has been cleared.
15.5
Self programming
The ATtiny4/5/9/10 don't support internal programming.
15.6
External Programming
The method for programming the Non-Volatile Memories by means of an external programmer is referred to as
external programming. External programming can be done both in-system or in mass production.
The Non-Volatile Memories can be externally programmed via the Tiny Programming Interface (TPI). For details
on the TPI, see “Programming interface” on page 95. Using the TPI, the external programmer can access the NVM
control and status registers mapped to I/O space and the NVM memory mapped to data memory space.
15.6.1
Entering External Programming Mode
The TPI must be enabled before external programming mode can be entered. The following procedure describes,
how to enter the external programming mode after the TPI has been enabled:
1. Make a request for enabling NVM programming by sending the NVM memory access key with the SKEY
instruction.
2. Poll the status of the NVMEN bit in TPISR until it has been set.
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Refer to the Tiny Programming Interface description on page 95 for more detailed information of enabling the TPI
and programming the NVM.
15.6.2
Exiting External Programming Mode
Clear the NVM enable bit to disable NVM programming, then release the RESET pin.
See NVMEN bit in “TPISR – Tiny Programming Interface Status Register” on page 105.
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15.7
15.7.1
Register Description
NVMCSR - Non-Volatile Memory Control and Status Register
Bit
7
6
5
4
3
2
1
NVMBSY
–
–
–
–
–
–
–
Read/Write
R/W
R
R
R
R
R
R
R
Initial Value
0
0
0
0
0
0
0
0
0x32
0
NVMCSR
• Bit 7 - NVMBSY: Non-Volatile Memory Busy
This bit indicates the NVM memory (Flash memory and Lock Bits) is busy, being programmed. This bit is set when
a program operation is started, and it remains set until the operation has been completed.
• Bit 6:0 - Res: Reserved Bits
These bits are reserved and will always be read as zero.
15.7.2
NVMCMD - Non-Volatile Memory Command Register
Bit
7
6
0x33
–
–
5
4
3
Read/Write
R
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
2
1
0
R/W
R/W
R/W
0
0
0
NVMCMD[5:0]
NVMCMD
• Bit 7:6 - Res: Reserved Bits
These bits are reserved and will always read zero.
• Bit 5:0 - NVMCMD[5:0]: Non-Volatile Memory Command
These bits define the programming commands for the flash, as shown in Table 15-10.
Table 15-10. NVM Programming commands
NVMCMD
Operation Type
Binary
Hex
Mnemonic
Description
0b000000
0x00
NO_OPERATION
No operation
0b010000
0x10
CHIP_ERASE
Chip erase
Section
0b010100
0x14
SECTION_ERASE
Section erase
Word
0b011101
0x1D
WORD_WRITE
Word write
General
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16. Electrical Characteristics
16.1
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
16.2
DC Characteristics
Table 16-1.
DC Characteristics. TA = -40C to +85C
Symbol
Parameter
Condition
Min.
VIL
Input Low Voltage
VCC = 1.8V - 2.4V
VCC = 2.4V - 5.5V
Input High-voltage
Except RESET pin
Max.
Units
-0.5
0.2VCC
0.3VCC
V
VCC = 1.8V - 2.4V
VCC = 2.4V - 5.5V
0.7VCC(1)
0.6VCC(1)
VCC +0.5(2)
V
Input High-voltage
RESET pin
VCC = 1.8V to 5.5V
0.9VCC(1)
VCC +0.5(2)
V
VOL
Output Low Voltage(3)
Except RESET pin(5)
IOL = 10 mA, VCC = 5V
IOL = 5 mA, VCC = 3V
0.6
0.5
V
VOH
Output High-voltage(4)
Except RESET pin(5)
IOH = -10 mA, VCC = 5V
IOH = -5 mA, VCC = 3V
ILIL
Input Leakage
Current I/O Pin
Vcc = 5.5V, pin low
(absolute value)
<0.05
1
µA
ILIH
Input Leakage
Current I/O Pin
Vcc = 5.5V, pin high
(absolute value)
<0.05
1
µA
RRST
Reset Pull-up Resistor
Vcc = 5.5V, input low
30
60
k
RPU
I/O Pin Pull-up Resistor
Vcc = 5.5V, input low
20
50
k
IACLK
Analog Comparator Input
Leakage Current
VCC = 5V
Vin = VCC/2
-50
50
nA
VIH
Typ.
4.3
2.5
V
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Table 16-1.
Symbol
DC Characteristics. TA = -40C to +85C (Continued)
Parameter
Condition
Power Supply Current(6)
ICC
Power-down mode(7)
Notes:
Min.
Typ.
Max.
Units
Active 1MHz, VCC = 2V
0.2
0.5
mA
Active 4MHz, VCC = 3V
0.8
1.2
mA
Active 8MHz, VCC = 5V
2.7
4
mA
Idle 1MHz, VCC = 2V
0.02
0.2
mA
Idle 4MHz, VCC = 3V
0.13
0.5
mA
Idle 8MHz, VCC = 5V
0.6
1.5
mA
WDT enabled, VCC = 3V
4.5
10
µA
WDT disabled, VCC = 3V
0.15
2
µA
1. “Min” means the lowest value where the pin is guaranteed to be read as high.
2. “Max” means the highest value where the pin is guaranteed to be read as low.
3. Although each I/O port can sink more than the test conditions (10 mA at VCC = 5V, 5 mA at VCC = 3V) under steady state
conditions (non-transient), the sum of all IOL (for all ports) should not exceed 60 mA. If IOL exceeds the test conditions, VOL
may exceed the related specification. Pins are not guaranteed to sink current greater than the listed test condition.
4. Although each I/O port can source more than the test conditions (10 mA at VCC = 5V, 5 mA at VCC = 3V) under steady state
conditions (non-transient), 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.
5. The RESET pin must tolerate high voltages when entering and operating in programming modes and, as a consequence,
has a weak drive strength as compared to regular I/O pins. See Figure 17-25 on page 134, and Figure 17-26 on page 134.
6. Values are with external clock using methods described in “Minimizing Power Consumption” on page 24. Power Reduction
is enabled (PRR = 0xFF) and there is no I/O drive.
7. BOD Disabled.
16.3
Speed
The maximum operating frequency of the device depends on VCC . The relationship between supply voltage and
maximum operating frequency is piecewise linear, as shown in Figure 16-1.
Figure 16-1. Maximum Frequency vs. VCC
12 MHz
8 MHz
4 MHz
1.8V
2.7V
4.5V
5.5V
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16.4
Clock Characteristics
16.4.1
Accuracy of Calibrated Internal Oscillator
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 17-39 on page 141 and Figure 17-40 on page 141.
Table 16-2.
Calibration Accuracy of Internal RC Oscillator
Calibration
Method
Target Frequency
VCC
Temperature
Accuracy at given Voltage
& Temperature(1)
Factory
Calibration
8.0 MHz
3V
25C
±10%
User
Calibration
Fixed frequency within:
7.3 – 8.1 MHz
Fixed voltage within:
1.8V – 5.5V
Fixed temp. within:
-40C – 85C
±1%
Notes:
16.4.2
1. Accuracy of oscillator frequency at calibration point (fixed temperature and fixed voltage).
External Clock Drive
Figure 16-2. External Clock Drive Waveform
V IH1
V IL1
Table 16-3.
External Clock Drive Characteristics
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
125
83
ns
tCHCX
High Time
100
50
33
ns
tCLCX
Low Time
100
50
33
ns
tCLCH
Rise Time
2.0
1
0.6
s
tCHCL
Fall Time
2.0
1
0.6
s
tCLCL
Change in period from one clock cycle to the next
2
2
2
%
Min.
Max.
Min.
Max.
Min.
Max.
Units
0
4
0
8
0
12
MHz
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16.5
System and Reset Characteristics
Table 16-4.
Symbol
Parameter
VRST
RESET Pin Threshold
Voltage
tRST
Minimum pulse width on
RESET Pin
tTOUT
Time-out after reset
Note:
16.5.1
Reset, VLM, and Internal Voltage Characteristics
Condition
Min(1)
Typ(1)
0.2 VCC
VCC = 1.8V
VCC = 3V
VCC = 5V
Max(1)
Units
0.9VCC
V
2000
700
400
32
ns
64
128
ms
1. Values are guidelines, only
Power-On Reset
Table 16-5.
Symbol
Characteristics of Enhanced Power-On Reset. TA = -40 - 85C
Parameter
Release threshold of power-on reset (2)
VPOR
VPOA
Activation threshold of power-on reset
SRON
Power-On Slope Rate
Note:
(3)
Min(1)
Typ(1)
Max(1)
Units
1.1
1.4
1.6
V
0.6
1.3
1.6
V
0.01
V/ms
1. Values are guidelines, only
2. Threshold where device is released from reset when voltage is rising
3. The Power-on Reset will not work unless the supply voltage has been below VPOA
16.5.2
VCC Level Monitor
Table 16-6.
Voltage Level Monitor Thresholds
Parameter
Min
Typ (1)
Max
Trigger level VLM1L
1.1
1.4
1.6
Trigger level VLM1H
1.4
1.6
1.8
Trigger level VLM2
2.0
2.5
2.7
Trigger level VLM3
3.2
3.7
4.5
Units
V
Settling time VMLM2,VLM3 (VLM1H,VLM1L)
Note:
5 (50)
µs
1. Typical values at room temperature
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16.6
Analog Comparator Characteristics
Table 16-7.
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
tDPD
16.7
Min
Symbol
Units
< 10
40
mV
50
nA
-50
ns
2
CLK
ADC Characteristics. T = -40C – 85C. VCC = 2.5V – 5.5V
Parameter
Condition
Min
Typ
Resolution
Max
Units
8
Bits
VREF = VCC = 4V,
ADC clock = 200 kHz
1.0
LSB
VREF = VCC = 4V,
ADC clock = 200 kHz
Noise Reduction Mode
1.0
LSB
Integral Non-Linearity (INL)
(Accuracy after Offset and
Gain Calibration)
VREF = VCC = 4V,
ADC clock = 200 kHz
1.0
LSB
Differential Non-linearity
(DNL)
VREF = VCC = 4V,
ADC clock = 200 kHz
0.5
LSB
Gain Error
VREF = VCC = 4V,
ADC clock = 200 kHz
1.0
LSB
Offset Error
VREF = VCC = 4V,
ADC clock = 200 kHz
1.0
LSB
Conversion Time
Free Running Conversion
Absolute accuracy
(Including INL, DNL, and
Quantization, Gain and Offset
Errors)
Clock Frequency
RAIN
Max
ADC Characteristics (ATtiny5/10, only)
Table 16-8.
VIN
Typ
Input Voltage
65
260
µs
50
200
kHz
GND
VREF
V
Input Bandwidth
7.7
kHz
Analog Input Resistance
100
M
ADC Conversion Output
0
255
LSB
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16.8
Serial Programming Characteristics
Figure 16-3. Serial Programming Timing
Receive Mode
Transmit Mode
TPIDATA
tIVCH
tCHIX
tCLOV
TPICLK
tCLCH
tCHCL
tCLCL
Table 16-9.
Serial Programming Characteristics, TA = -40C to 85C, VCC = 5V ± 5% (Unless Otherwise Noted)
Symbol
Parameter
1/tCLCL
Clock Frequency
Min
Typ
Max
Units
2
MHz
tCLCL
Clock Period
500
ns
tCLCH
Clock Low Pulse Width
200
ns
tCHCH
Clock High Pulse Width
200
ns
tIVCH
Data Input to Clock High Setup Time
50
ns
tCHIX
Data Input Hold Time After Clock High
100
ns
tCLOV
Data Output Valid After Clock Low Time
200
ns
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17. 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 pullups 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.
17.1
Supply Current of I/O Modules
Tables and formulas below can be used to calculate additional current consumption for the different I/O modules in
Active and Idle mode. Enabling and disabling of I/O modules is controlled by the Power Reduction Register. See
“Power Reduction Register” on page 24 for details.
Table 17-1.
Additional Current Consumption for the different I/O modules (absolute values)
PRR bit
Typical numbers
VCC = 2V, f = 1MHz
VCC = 3V, f = 4MHz
VCC = 5V, f = 8MHz
6.6 uA
40.0 uA
153.0 uA
29.6 uA
88.3 uA
333.3 uA
PRTIM0
PRADC (1)
Note:
1. The ADC is available in ATtiny5/10, only
Table 17-2 below can be used for calculating typical current consumption for other supply voltages and frequencies
than those mentioned in the Table 17-1 above.
Table 17-2.
Additional Current Consumption (percentage) in Active and Idle mode
PRR bit
Current consumption additional to
active mode with external clock
(see Figure 17-1 and Figure 17-2)
Current consumption additional to
idle mode with external clock
(see Figure 17-7 and Figure 17-8)
PRTIM0
2.3 %
10.4 %
PRADC (1)
6.7 %
28.8 %
Note:
1. The ADC is available in ATtiny5/10, only
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Active Supply Current
Figure 17-1. Active Supply Current vs. Low Frequency (0.1 - 1.0 MHz)
ACTIVE SUPPLY CURRENT vs. LOW FREQUENCY
(PRR=0xFF)
0.7
5.5 V
0.6
5.0 V
0.5
4.5 V
ICC (mA)
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)
Figure 17-2. Active Supply Current vs. frequency (1 - 12 MHz)
ACTIVE SUPPLY CURRENT vs. FREQUENCY
(PRR=0xFF)
5
4.5
5.5 V
4
5.0 V
3.5
4.5 V
3
ICC (mA)
17.2
2.5
4.0 V
2
1.5
3.3 V
1
2.7 V
0.5
1.8 V
0
0
2
4
6
8
10
12
Frequency (MHz)
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Figure 17-3. Active Supply Current vs. VCC (Internal Oscillator, 8 MHz)
ACTIVE SUPPLY CURRENT vs. VCC
INTERNAL OSCILLATOR, 8 MHz
3.5
-40 °C
25 °C
85 °C
3
ICC (mA)
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 17-4. Active Supply Current vs. VCC (Internal Oscillator, 1 MHz)
ACTIVE SUPPLY CURRENT vs. VCC
INTERNAL OSCILLATOR, 1 MHz
1
0.9
-40 °C
25 °C
85 °C
0.8
0.7
ICC (mA)
0.6
0.5
0.4
0.3
0.2
0.1
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
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Figure 17-5. Active Supply Current vs. VCC (Internal Oscillator, 128 kHz)
ACTIVE SUPPLY CURRENT vs. VCC
INTERNAL OSCILLATOR, 128 KHz
0.12
-40 °C
25 °C
85 °C
0.1
ICC (mA)
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)
Figure 17-6. Active Supply Current vs. VCC (External Clock, 32 kHz)
ACTIVE SUPPLY CURRENT vs. VCC
INTERNAL OSCILLATOR, 32 KHz
0.04
-40 °C
85 °C
25 °C
0.035
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)
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Idle Supply Current
Figure 17-7. Idle Supply Current vs. Low Frequency (0.1 - 1.0 MHz)
IDLE SUPPLY CURRENT vs. LOW FREQUENCY
(PRR=0xFF)
0,1
0,09
5.5 V
ICC (mA)
0,08
0,07
5.0 V
0,06
4.5 V
0,05
4.0 V
0,04
3.3 V
0,03
2.7 V
0,02
1.8 V
0,01
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1
Frequency (MHz)
Figure 17-8. Idle Supply Current vs. Frequency (1 - 12 MHz)
IDLE SUPPLY CURRENT vs. FREQUENCY
(PRR=0xFF)
1
5.5 V
5.0 V
0,8
4.5 V
0,6
ICC (mA)
17.3
4.0 V
0,4
3.3 V
0,2
2.7 V
1.8 V
0
0
2
4
6
8
10
12
Frequency (MHz)
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Figure 17-9. Idle Supply Current vs. VCC (Internal Oscillator, 8 MHz)
IDLE SUPPLY CURRENT vs. VCC
INTERNAL RC OSCILLATOR, 8 MHz
0,7
85 °C
25 °C
-40 °C
0,6
ICC (mA)
0,5
0,4
0,3
0,2
0,1
0
1,5
2
2,5
3
3,5
4
4,5
5
5,5
VCC (V)
Figure 17-10. Idle Supply Current vs. VCC (Internal Oscillator, 1 MHz)
IDLE SUPPLY CURRENT vs. VCC
INTERNAL RC OSCILLATOR, 1 MHz
0,7
0,6
ICC (mA)
0,5
0,4
0,3
85 °C
25 °C
-40 °C
0,2
0,1
0
1,5
2
2,5
3
3,5
4
4,5
5
5,5
VCC (V)
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Power-down Supply Current
Figure 17-11. Power-down Supply Current vs. VCC (Watchdog Timer Disabled)
POWER-DOWN SUPPLY CURRENT vs. VCC
WATCHDOG TIMER DISABLED
0.5
85 °C
0.45
0.4
0.35
ICC (uA)
0.3
0.25
0.2
0.15
25 °C
0.1
-40 °C
0.05
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
Figure 17-12. Power-down Supply Current vs. VCC (Watchdog Timer Enabled)
POWER-DOWN SUPPLY CURRENT vs. VCC
WATCHDOG TIMER ENABLED
9
-40 °C
8
25 °C
85 °C
7
6
ICC (uA)
17.4
5
4
3
2
1
0
1,5
2
2,5
3
3,5
4
4,5
5
5,5
VCC (V)
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Pin Pull-up
Figure 17-13. I/O pin Pull-up Resistor Current vs. Input Voltage (VCC = 1.8V)
I/O PIN PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE
60
50
IOP (uA)
40
30
20
10
25 °C
85 °C
-40 °C
0
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
VOP (V)
Figure 17-14. I/O Pin Pull-up Resistor Current vs. input Voltage (VCC = 2.7V)
I/O PIN PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE
80
70
60
50
IOP (uA)
17.5
40
30
20
10
25 °C
85 °C
-40 °C
0
0
0,5
1
1,5
2
2,5
3
VOP (V)
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128
Figure 17-15. I/O pin Pull-up Resistor Current vs. Input Voltage (VCC = 5V)
I/O PIN PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE
160
140
120
IOP (uA)
100
80
60
40
20
25 °C
85 °C
-40 °C
0
0
1
2
3
4
5
6
VOP (V)
Figure 17-16. Reset Pull-up Resistor Current vs. Reset Pin Voltage (VCC = 1.8V)
RESET PULL-UP RESISTOR CURRENT vs. RESET PIN VOLTAGE
40
35
30
IRESET (uA)
25
20
15
10
5
25 °C
-40 °C
85 °C
0
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
VRESET (V)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
129
Figure 17-17. Reset Pull-up Resistor Current vs. Reset Pin Voltage (VCC = 2.7V)
RESET PULL-UP RESISTOR CURRENT vs. RESET PIN VOLTAGE
60
50
IRESET (uA)
40
30
20
10
25 °C
-40 °C
85 °C
0
0
0,5
1
1 ,5
2,5
2
3
VRESET (V)
Figure 17-18. Reset Pull-up Resistor Current vs. Reset Pin Voltage (VCC = 5V)
RESET PULL-UP RESISTOR CURRENT vs. RESET PIN VOLTAGE
120
100
IRESET (uA)
80
60
40
20
25 °C
-40 °C
85 °C
0
0
0,5
1
1,5
2
2,5
3
3,5
4
4,5
5
VRESET (V)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
130
Pin Driver Strength
Figure 17-19. I/O Pin Output Voltage vs. Sink Current (VCC = 1.8V)
I/O PIN OUTPUT VOLTAGE vs. SINK CURRENT
VCC = 1.8V
0.8
0.7
85 °C
0.6
VOL (V)
0.5
25 °C
0.4
-40 °C
0.3
0.2
0.1
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
IOL (mA)
Figure 17-20. I/O Pin Output Voltage vs. Sink Current (VCC = 3V)
I/O PIN OUTPUT VOLTAGE vs. SINK CURRENT
VCC = 3V
0.8
0.7
85 °C
0.6
0.5
VOL (V)
17.6
25 °C
-40 °C
0.4
0.3
0.2
0.1
0
0
1
2
3
4
5
6
7
8
9
10
IOL (mA)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
131
Figure 17-21. I/O pin Output Voltage vs. Sink Current (VCC = 5V)
I/O PIN OUTPUT VOLTAGE vs. SINK CURRENT
VCC = 5V
1
85 °C
0.8
-40 °C
25 °C
VOL (V)
0.6
0.4
0.2
0
0
2
4
6
8
10
12
14
16
18
20
IOL (mA)
Figure 17-22. I/O Pin Output Voltage vs. Source Current (VCC = 1.8V)
I/O PIN OUTPUT VOLTAGE vs. SOURCE CURRENT
VCC = 1.8V
2
1.8
1.6
VOH (V)
1.4
1.2
-40 °C
1
25 °C
0.8
85 °C
0.6
0.4
0.2
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
IOH (mA)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
132
Figure 17-23. I/O Pin Output Voltage vs. Source Current (VCC = 3V)
I/O PIN OUTPUT VOLTAGE vs. SOURCE CURRENT
VCC = 3V
3.1
2.9
VOH (V)
2.7
2.5
-40 °C
25 °C
2.3
85 °C
2.1
1.9
1.7
1.5
0
1
2
3
4
5
6
7
8
9
10
IOH (mA)
Figure 17-24. I/O Pin output Voltage vs. Source Current (VCC = 5V)
I/O PIN OUTPUT VOLTAGE vs. SOURCE CURRENT
VCC = 5V
5.2
5
VOH (V)
4.8
4.6
4.4
-40 °C
25 °C
4.2
85 °C
4
0
2
4
6
8
10
12
14
16
18
20
IOH (mA)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
133
Figure 17-25. Reset Pin as I/O, Output Voltage vs. Sink Current
OUTPUT VOLTAGE vs. SINK CURRENT
RESET PIN AS I/O
1
3.0 V
1.8 V
0.9
0.8
0.7
5.0 V
VOL (V)
0.6
0.5
0.4
0.3
0.2
0.1
0
0
1
2
3
4
IOL (mA)
Figure 17-26. Reset Pin as I/O, Output Voltage vs. Source Current
OUTPUT VOLTAGE vs. SOURCE CURRENT
RESET PIN AS I/O
5
4
VOH (V)
3
5.0 V
2
1
3.0 V
1.8 V
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
IOH (mA)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
134
Pin Threshold and Hysteresis
Figure 17-27. I/O Pin Input Threshold Voltage vs. VCC (VIH, IO Pin Read as ‘1’)
I/O PIN INPUT THRESHOLD VOLTAGE vs. VCC
VIH, IO PIN READ AS '1'
3,5
85 °C
25 °C
-40 °C
3
Threshold (V)
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 17-28. I/O Pin Input threshold Voltage vs. VCC (VIL, IO 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
2
Threshold (V)
17.7
1,5
1
0,5
0
1,5
2
2,5
3
3,5
4
4,5
5
5,5
VCC (V)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
135
Figure 17-29. I/O Pin Input Hysteresis vs. VCC
I/O PIN INPUT HYSTERESIS vs. VCC
1
0,9
0,8
Input Hysteresis (V)
0,7
0,6
-40 °C
0,5
25 °C
0,4
85 °C
0,3
0,2
0,1
0
1,5
2
2,5
3
3,5
4
4,5
5
5,5
VCC (V)
Figure 17-30. Reset Pin as I/O, Input Threshold Voltage vs. VCC (VIH, I/O Pin Read as ‘1’)
RESET PIN AS I/O THRESHOLD VOLTAGE vs. VCC
VIH, RESET READ AS '1'
3
-40 °C
25 °C
85 °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
VCC (V)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
136
Figure 17-31. Reset Pin as I/O, Input Threshold Voltage vs. VCC (VIL, I/O pin Read as ‘0’)
RESET PIN AS I/O THRESHOLD VOLTAGE vs. VCC
VIL, RESET READ AS '0'
2,5
85 °C
25 °C
-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
4,5
5
5,5
VCC (V)
Figure 17-32. Reset Input Hysteresis vs. VCC (Reset Pin Used as I/O)
RESET PIN AS I/O, INPUT HYSTERESIS vs. VCC
VIL, PIN READ AS "0"
1
0,9
Input Hysteresis (V)
0,8
0,7
-40 °C
25 °C
0,6
0,5
85 °C
0,4
0,3
0,2
0,1
0
1,5
2
2,5
3
3,5
4
VCC (V)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
137
Figure 17-33. Reset Input Threshold Voltage vs. VCC (VIH, I/O 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
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 17-34. Reset Input Threshold Voltage vs. VCC (VIL, I/O pin Read as ‘0’)
RESET INPUT THRESHOLD VOLTAGE vs. VCC
VIL, IO PIN READ AS '0'
2,5
85 °C
25 °C
-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)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
138
Figure 17-35. Reset Pin, Input Hysteresis vs. VCC
RESET PIN INPUT HYSTERESIS vs. VCC
1
Input Hysteresis (V)
0,8
0,6
-40 °C
0,4
25 °C
85 °C
0,2
0
1,5
2
2,5
3
3,5
4
4,5
5
5,5
VCC (V)
Analog Comparator Offset
Figure 17-36. Analog Comparator Offset
ANALOG COMPARATOR OFFSET
VCC = 5V
0.006
-40
0.004
Offset
17.8
25
0.002
85
0
0
1
2
3
4
5
VIN
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
139
Internal Oscillator Speed
Figure 17-37. Watchdog Oscillator Frequency vs. VCC
WATCHDOG OSCILLATOR FREQUENCY vs. OPERATING VOLTAGE
110
109
108
Frequency (kHz)
107
-40 °C
106
105
25 °C
104
103
102
101
85 °C
100
99
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
Figure 17-38. Watchdog Oscillator Frequency vs. Temperature
WATCHDOG OSCILLATOR FREQUENCY vs. TEMPERATURE
110
109
108
107
Frequency (kHz)
17.9
106
105
104
1.8 V
103
2.7 V
102
3.3 V
101
4.0 V
5.5 V
100
-60
-40
-20
0
20
40
60
80
100
Temperature
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
140
Figure 17-39. Calibrated Oscillator Frequency vs. VCC
CALIBRATED 8.0MHz OSCILLATOR FREQUENCY vs. OPERATING VOLTAGE
8.4
-40 °C
8.2
Frequency (MHz)
25 °C
85 °C
8
7.8
7.6
7.4
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
Figure 17-40. Calibrated Oscillator Frequency vs. Temperature
CALIBRATED 8.0MHz OSCILLATOR FREQUENCY vs. TEMPERATURE
8.3
8.2
Frequency (MHz)
8.1
8
7.9
5.0 V
7.8
3.0 V
7.7
1.8 V
7.6
-40
-20
0
20
40
60
80
100
Temperature
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
141
Figure 17-41. Calibrated Oscillator Frequency vs, OSCCAL Value
CALIBRATED 8.0MHz RC OSCILLATOR FREQUENCY vs. OSCCAL VALUE
VCC = 3V
16
25 °C
85 °C
-40 °C
14
Frequency (MHz)
12
10
8
6
4
2
0
0
16
32
48
64
80
96
112 128 144 160 176 192 208 224 240
OSCCAL (X1)
17.10 VLM Thresholds
Figure 17-42. VLM1L Threshold of VCC Level Monitor
VLM THRESHOLD vs. TEMPERATURE
VLM2:0 = 001
1.42
1.41
Threshold (V)
1.4
1.39
1.38
1.37
1.36
1.35
1.34
-40
-20
0
20
40
60
80
100
Temperature (C)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
142
Figure 17-43. VLM1H Threshold of VCC Level Monitor
VLM THRESHOLD vs. TEMPERATURE
VLM2:0 = 010
1.7
Threshold (V)
1.65
1.6
1.55
1.5
1.45
1.4
-40
-20
0
20
40
60
80
100
60
80
100
Temperature (C)
Figure 17-44. VLM2 Threshold of VCC Level Monitor
VLM THRESHOLD vs. TEMPERATURE
VLM2:0 = 011
2.48
Threshold (V)
2.47
2.46
2.45
2.44
2.43
-40
-20
0
20
40
Temperature (C)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
143
Figure 17-45. VLM3 Threshold of VCC Level Monitorr2
VLM THRESHOLD vs. TEMPERATURE
VLM2:0 = 100
3.9
Threshold (V)
3.8
3.7
3.6
3.5
3.4
-40
-20
0
20
40
60
80
100
Temperature (C)
17.11 Current Consumption of Peripheral Units
Figure 17-46. ADC Current vs. VCC (ATtiny5/10, only)
ADC CURRENT vs. VCC
4.0 MHz FREQUENCY
700
600
ICC (uA)
500
400
300
200
100
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
144
Figure 17-47. Analog Comparator Current vs. VCC
ANALOG COMPARATOR CURRENT vs. VCC
140
120
ICC (uA)
100
25 ˚C
80
60
40
20
0
1,5
2
2,5
3
3,5
4
4,5
5
5,5
VCC (V)
Figure 17-48. VCC Level Monitor Current vs. VCC
VLM SUPPLY CURRENT vs. VCC
0.35
0.3
VLM2:0 = 001
VLM2:0 = 010
VLM2:0 = 011
0.25
ICC (mA)
VLM2:0 = 100
0.2
0.15
0.1
0.05
0
VLM2:0 = 000
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
145
Figure 17-49. Temperature Dependence of VLM Current vs. VCC
VLM SUPPLY CURRENT vs. VCC
VLM2:0 = 001
350
-40 °C
300
25 °C
85 °C
ICC (uA)
250
200
150
100
50
0
1.5
2
2.5
3
3.5
4
4.5
5
5.5
VCC (V)
Figure 17-50. Watchdog Timer Current vs. VCC
WATCHDOG TIMER CURRENT vs. VCC
9
-40 °C
25 °C
85 °C
8
7
ICC (uA)
6
5
4
3
2
1
0
1,5
2
2,5
3
3,5
4
4,5
5
5,5
VCC (V)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
146
17.12 Current Consumption in Reset and Reset Pulsewidth
Figure 17-51. Reset Supply Current vs. VCC (0.1 - 1.0 MHz, excluding Current Through the Reset Pull-up)
RESET SUPPLY CURRENT vs. VCC
EXCLUDING CURRENT THROUGH THE RESET PULLUP
0,5
0,4
5.5 V
5.0 V
4.5 V
4.0 V
3.3 V
2.7 V
ICC (mA)
0,3
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)
Note:
The default clock source for the device is always the internal 8 MHz oscillator. Hence, current consumption in reset
remains unaffected by external clock signals.
Figure 17-52. Minimum Reset Pulse Width vs. VCC
MINIMUM RESET PULSE WIDTH vs. VCC
2500
Pulsewidth (ns)
2000
1500
1000
500
85 °C
25 °C
-40 °C
0
1,5
2
2,5
3
3,5
4
4,5
5
5,5
VCC (V)
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
147
18. 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 12
0x3E
SPH
Stack Pointer High Byte
Page 12
0x3D
SPL
Stack Pointer Low Byte
Page 12
Note:
0x3C
CCP
0x3B
RSTFLR
–
–
–
CPU Change Protection Byte
0x3A
SMCR
–
–
–
0x39
OSCCAL
Page 11
–
WDRF
–
EXTRF
PORF
–
SM2
SM1
SM0
SE
Page 34
Page 25
Oscillator Calibration Byte
Page 21
0x38
Reserved
–
–
–
–
–
–
–
–
0x37
CLKMSR
–
–
–
–
–
–
CLKMS1
CLKMS0
Page 21
0x36
CLKPSR
–
–
–
–
CLKPS3
CLKPS2
CLKPS1
CLKPS0
Page 22
0x35
PRR
–
–
–
–
–
–
PRADC
PRTIM0
Page 26
0x34
VLMCSR
VLMF
VLMIE
–
–
–
VLM2
VLM1
VLM0
Page 33
0x33
NVMCMD
–
–
0x32
NVMCSR
NVMBSY
–
–
–
–
–
–
–
Page 114
0x31
WDTCSR
WDIF
WDIE
WDP3
–
WDE
WDP2
WDP1
WDP0
Page 32
0x30
Reserved
–
–
–
–
–
–
–
–
NVM Comman
Page 114
0x2F
GTCCR
TSM
–
–
–
–
–
–
PSR
0x2E
TCCR0A
COM0A1
COM0A0
COM0B1
COM0B0
–
–
WGM01
WGM00
Page 78
Page 72
0x2D
TCCR0B
ICNC0
ICES0
–
WGM03
WGM02
CS02
CS01
CS00
Page 74
0x2C
TCCR0C
FOC0A
FOC0B
–
–
–
–
–
–
Page 75
0x2B
TIMSK0
–
–
ICIE0
–
–
OCIE0B
OCIE0A
TOIE0
Page 77
0x2A
TIFR0
–
–
ICF0
–
–
OCF0B
OCF0A
TOV0
0x29
TCNT0H
Page 78
Timer/Counter0 – Counter Register High Byte
Page 76
0x28
TCNT0L
Timer/Counter0 – Counter Register Low Byte
Page 76
0x27
OCR0AH
Timer/Counter0 – Compare Register A High Byte
Page 76
0x26
OCR0AL
Timer/Counter0 – Compare Register A Low Byte
Page 76
0x25
OCR0BH
Timer/Counter0 – Compare Register B High Byte
Page 76
0x24
OCR0BL
Timer/Counter0 – Compare Register B Low Byte
Page 76
0x23
ICR0H
Timer/Counter0 - Input Capture Register High Byte
Page 77
0x22
ICR0L
Timer/Counter0 - Input Capture Register Low Byte
Page 77
0x21
Reserved
–
–
–
–
–
–
–
0x20
Reserved
–
–
–
–
–
–
–
–
0x1F
ACSR
ACD
–
ACO
ACI
ACIE
ACIC
ACIS1
ACIS0
0x1E
Reserved
–
–
–
–
–
–
–
–
0x1D
ADCSRA
ADEN
ADSC
ADATE
ADIF
ADIE
ADPS2
ADPS1
ADPS0
Page 92
0x1C
ADCSRB
–
–
–
–
–
ADTS2
ADTS1
ADTS0
Page 93
0x1B
ADMUX
–
–
–
–
–
–
MUX1
MUX0
Page 92
0x1A
Reserved
–
–
–
–
–
–
–
–
–
Page 80
0x19
ADCL
0x18
Reserved
–
–
–
ADC Conversion Result
–
–
–
–
–
Page 94
0x17
DIDR0
–
–
–
–
ADC3D
ADC2D
ADC1D
ADC0D
0x16
Reserved
–
–
–
–
–
–
–
–
0x15
EICRA
–
–
–
–
–
–
ISC01
ISC00
0x14
EIFR
–
–
–
–
–
–
–
INTF0
Page 38
0x13
EIMSK
–
–
–
–
–
–
–
INT0
Page 38
0x12
PCICR
–
–
–
–
–
–
–
PCIE0
Page 39
0x11
PCIFR
–
–
–
–
–
–
–
PCIF0
Page 39
0x10
PCMSK
–
–
–
–
PCINT3
PCINT2
PCINT1
PCINT0
Page 39
0x0F
Reserved
–
–
–
–
–
–
–
–
Page 81, Page 94
Page 37
0x0E
Reserved
–
–
–
–
–
–
–
–
0x0D
Reserved
–
–
–
–
–
–
–
–
0x0C
PORTCR
–
–
–
–
–
–
BBMB
–
0x0B
Reserved
–
–
–
–
–
–
–
–
0x0A
Reserved
–
–
–
–
–
–
–
–
0x09
Reserved
–
–
–
–
–
–
–
–
0x08
Reserved
–
–
–
–
–
–
–
–
0x07
Reserved
–
–
–
–
–
–
–
–
0x06
Reserved
–
–
–
–
–
–
–
–
0x05
Reserved
–
–
–
–
–
–
–
–
0x04
Reserved
–
–
–
–
–
–
–
–
0x03
PUEB
–
–
–
–
PUEB3
PUEB2
PUEB1
PUEB0
0x02
PORTB
–
–
–
–
PORTB3
PORTB2
PORTB1
PORTB0
Page 51
0x01
DDRB
–
–
–
–
DDRB3
DDRB2
DDRB1
DDRB0
Page 51
0x00
PINB
–
–
–
–
PINB3
PINB2
PINB1
PINB0
Page 51
Page 50
Page 50
1. For compatibility with future devices, reserved bits should be written to zero if accessed. Reserved I/O memory addresses
ATtiny4/5/9/10 [DATASHEET]
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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.
3. 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 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.
4. The ADC is available in ATtiny5/10, only.
ATtiny4/5/9/10 [DATASHEET]
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19. Instruction Set Summary
Mnemonics
Operands
Description
Operation
Flags
#Clocks
ARITHMETIC AND LOGIC INSTRUCTIONS
ADD
Rd, Rr
Add without Carry
Rd  Rd + Rr
Z,C,N,V,S,H
ADC
Rd, Rr
Add with Carry
Rd  Rd + Rr + C
Z,C,N,V,S,H
1
SUB
Rd, Rr
Subtract without Carry
Rd  Rd - Rr
Z,C,N,V,S,H
1
1
SUBI
Rd, K
Subtract Immediate
Rd  Rd - K
Z,C,N,V,S,H
1
SBC
Rd, Rr
Subtract with Carry
Rd  Rd - Rr - C
Z,C,N,V,S,H
1
SBCI
Rd, K
Subtract Immediate with Carry
Rd  Rd - K - C
Z,C,N,V,S,H
1
AND
Rd, Rr
Logical AND
Rd Rd  Rr
Z,N,V,S
1
ANDI
Rd, K
Logical AND with Immediate
Rd  Rd K
Z,N,V,S
1
OR
Rd, Rr
Logical OR
Rd  Rd v Rr
Z,N,V,S
1
ORI
Rd, K
Logical OR with Immediate
Rd Rd v K
Z,N,V,S
1
EOR
Rd, Rr
Exclusive OR
Rd  Rd  Rr
Z,N,V,S
1
1
COM
Rd
One’s Complement
Rd  $FF  Rd
Z,C,N,V,S
NEG
Rd
Two’s Complement
Rd  $00  Rd
Z,C,N,V,S,H
1
SBR
Rd,K
Set Bit(s) in Register
Rd  Rd v K
Z,N,V,S
1
1
CBR
Rd,K
Clear Bit(s) in Register
Rd  Rd  ($FFh - K)
Z,N,V,S
INC
Rd
Increment
Rd  Rd + 1
Z,N,V,S
1
DEC
Rd
Decrement
Rd  Rd  1
Z,N,V,S
1
TST
Rd
Test for Zero or Minus
Rd  Rd  Rd
Z,N,V,S
1
CLR
Rd
Clear Register
Rd  Rd  Rd
Z,N,V,S
1
SER
Rd
Set Register
Rd  $FF
None
1
Relative Jump
PC PC + k + 1
None
2
Indirect Jump to (Z)
PC(15:0)  Z, PC(21:16)  0
None
2
BRANCH INSTRUCTIONS
RJMP
k
IJMP
Relative Subroutine Call
PC  PC + k + 1
None
3/4
ICALL
Indirect Call to (Z)
PC(15:0)  Z, PC(21:16)  0
None
3/4
RET
Subroutine Return
PC  STACK
None
4/5
RETI
Interrupt Return
PC  STACK
I
if (Rd = Rr) PC PC + 2 or 3
None
RCALL
k
4/5
CPSE
Rd,Rr
Compare, Skip if Equal
1/2/3
CP
Rd,Rr
Compare
Rd  Rr
Z, C,N,V,S,H
1
CPC
Rd,Rr
Compare with Carry
Rd  Rr  C
Z, C,N,V,S,H
1
CPI
Rd,K
Compare with Immediate
Rd  K
Z, C,N,V,S,H
SBRC
Rr, b
Skip if Bit in Register Cleared
if (Rr(b)=0) PC  PC + 2 or 3
None
1
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
A, b
Skip if Bit in I/O Register Cleared
if (I/O(A,b)=0) PC  PC + 2 or 3
None
1/2/3
SBIS
A, b
Skip if Bit in I/O Register is Set
if (I/O(A,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
LSL
Rd
Logical Shift Left
Rd(n+1)  Rd(n), Rd(0)  0
Z,C,N,V,H
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,H
1
ROR
Rd
Rotate Right Through Carry
Rd(7)C,Rd(n) Rd(n+1),CRd(0)
Z,C,N,V
1
ASR
Rd
Arithmetic Shift Right
Rd(n)  Rd(n+1), n=0..6
Z,C,N,V
1
SWAP
Rd
Swap Nibbles
Rd(3..0)Rd(7..4),Rd(7..4)Rd(3..0)
None
1
BSET
s
Flag Set
SREG(s)  1
SREG(s)
1
BCLR
s
Flag Clear
SREG(s)  0
SREG(s)
1
SBI
A, b
Set Bit in I/O Register
I/O(A, b)  1
None
1
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150
Mnemonics
Operands
Description
Operation
Flags
#Clocks
CBI
A, b
Clear Bit in I/O Register
I/O(A, b)  0
None
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
1
1
SEC
Set Carry
C1
C
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
1
SES
Set Signed Test Flag
S1
S
CLS
Clear Signed Test Flag
S0
S
1
SEV
Set Two’s Complement Overflow.
V1
V
1
CLV
Clear Two’s Complement Overflow
V0
V
1
SET
Set T in SREG
T1
T
1
CLT
Clear T in SREG
T0
T
1
SEH
CLH
Set Half Carry Flag in SREG
Clear Half Carry Flag in SREG
H1
H0
H
H
1
1
DATA TRANSFER INSTRUCTIONS
MOV
Rd, Rr
Copy Register
Rd  Rr
None
1
LDI
Rd, K
Load Immediate
Rd  K
None
1
1/2
LD
Rd, X
Load Indirect
Rd  (X)
None
LD
Rd, X+
Load Indirect and Post-Increment
Rd  (X), X  X + 1
None
2
LD
Rd, - X
Load Indirect and Pre-Decrement
X  X - 1, Rd  (X)
None
2/3
1/2
LD
Rd, Y
Load Indirect
Rd  (Y)
None
LD
Rd, Y+
Load Indirect and Post-Increment
Rd  (Y), Y  Y + 1
None
2
LD
Rd, - Y
Load Indirect and Pre-Decrement
Y  Y - 1, Rd  (Y)
None
2/3
1/2
LD
Rd, Z
Load Indirect
Rd  (Z)
None
LD
Rd, Z+
Load Indirect and Post-Increment
Rd  (Z), Z  Z+1
None
2
LD
Rd, -Z
Load Indirect and Pre-Decrement
Z  Z - 1, Rd  (Z)
None
2/3
LDS
Rd, k
Store Direct from SRAM
Rd k)
None
1
ST
X, Rr
Store Indirect
(X) Rr
None
1
ST
X+, Rr
Store Indirect and Post-Increment
(X) Rr, X  X + 1
None
1
ST
- X, Rr
Store Indirect and Pre-Decrement
X  X - 1, (X)  Rr
None
2
ST
Y, Rr
Store Indirect
(Y)  Rr
None
1
ST
Y+, Rr
Store Indirect and Post-Increment
(Y)  Rr, Y  Y + 1
None
1
ST
- Y, Rr
Store Indirect and Pre-Decrement
Y  Y - 1, (Y)  Rr
None
2
ST
Z, Rr
Store Indirect
(Z)  Rr
None
1
ST
Z+, Rr
Store Indirect and Post-Increment.
(Z)  Rr, Z  Z + 1
None
1
ST
-Z, Rr
Store Indirect and Pre-Decrement
Z  Z - 1, (Z)  Rr
None
2
STS
k, Rr
Store Direct to SRAM
(k)  Rr
None
1
IN
Rd, A
In from I/O Location
Rd  I/O (A)
None
1
OUT
A, Rr
Out to I/O Location
I/O (A)  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
BREAK
Break
(see specific descr. for Break)
None
1
NOP
No Operation
None
1
SLEEP
WDR
Sleep
Watchdog Reset
None
None
1
(see specific descr. for Sleep)
(see specific descr. for WDR)
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151
20. Ordering Information
20.1
ATtiny4
Supply Voltage
Speed (1)
Temperature
Package (2)
Industrial
(-40C to 85C) (4)
6ST1
ATtiny4-TSHR(5)
12 MHz
8MA4
ATtiny4-MAHR (6)
6ST1
ATtiny4-TS8R (5)
1.8 – 5.5V
10 MHz
Notes:
Extended
(-40C to 125C) (6)
Ordering Code (3)
1. For speed vs. supply voltage, see section 16.3 “Speed” on page 116.
2. All packages are Pb-free, halide-free and fully green and they comply with the European directive for Restriction of Hazardous Substances (RoHS). NiPdAu finish.
3. Tape and reel.
4. Can also be supplied in wafer form. Contact your local Atmel sales office for ordering information and minimum quantities.
5. Top/bottomside markings:
– Top: T4x, where x = die revision
– Bottom: zHzzz or z8zzz, where H = (-40C to 85C), and 8 = (-40C to 125C)
6. For typical and Electrical characteristics for this device please consult Appendix A, ATtiny4/5/9/10 Specification at 125°C.
Package Type
6ST1
6-lead, 2.90 x 1.60 mm Plastic Small Outline Package (SOT23)
8MA4
8-pad, 2 x 2 x 0.6 mm Plastic Ultra Thin Dual Flat No Lead (UDFN)
ATtiny4/5/9/10 [DATASHEET]
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20.2
ATtiny5
Supply Voltage
Speed (1)
Temperature
Package (2)
Industrial
(-40C to 85C) (4)
6ST1
ATtiny5-TSHR (5)
12 MHz
8MA4
ATtiny5-MAHR (6)
6ST1
ATtiny5-TS8R (5)
1.8 – 5.5V
10 MHz
Notes:
Extended
(-40C to 125C) (6)
Ordering Code (3)
1. For speed vs. supply voltage, see section 16.3 “Speed” on page 116.
2. All packages are Pb-free, halide-free and fully green and they comply with the European directive for Restriction of Hazardous Substances (RoHS). NiPdAu finish.
3. Tape and reel.
4. Can also be supplied in wafer form. Contact your local Atmel sales office for ordering information and minimum quantities.
5. Top/bottomside markings:
– Top: T5x, where x = die revision
– Bottom: zHzzz or z8zzz, where H = (-40C to 85C), and 8 = (-40C to 125C)
6. For typical and Electrical characteristics for this device please consult Appendix A, ATtiny4/5/9/10 Specification at 125°C.
Package Type
6ST1
6-lead, 2.90 x 1.60 mm Plastic Small Outline Package (SOT23)
8MA4
8-pad, 2 x 2 x 0.6 mm Plastic Ultra Thin Dual Flat No Lead (UDFN)
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20.3
ATtiny9
Supply Voltage
Speed (1)
Temperature
Package (2)
Industrial
(-40C to 85C) (4)
6ST1
ATtiny9-TSHR (5)
12 MHz
8MA4
ATtiny9-MAHR (6)
6ST1
ATtiny9-TS8R (5)
1.8 – 5.5V
10 MHz
Notes:
Extended
(-40C to 125C) (6)
Ordering Code (3)
1. For speed vs. supply voltage, see section 16.3 “Speed” on page 116.
2. All packages are Pb-free, halide-free and fully green and they comply with the European directive for Restriction of Hazardous Substances (RoHS). NiPdAu finish.
3. Tape and reel.
4. Can also be supplied in wafer form. Contact your local Atmel sales office for ordering information and minimum quantities.
5. Top/bottomside markings:
– Top: T9x, where x = die revision
– Bottom: zHzzz or z8zzz, where H = (-40C to 85C), and 8 = (-40C to 125C)
6. For typical and Electrical characteristics for this device please consult Appendix A, ATtiny4/5/9/10 Specification at 125°C.
Package Type
6ST1
6-lead, 2.90 x 1.60 mm Plastic Small Outline Package (SOT23)
8MA4
8-pad, 2 x 2 x 0.6 mm Plastic Ultra Thin Dual Flat No Lead (UDFN)
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20.4
ATtiny10
Supply Voltage
Speed (1)
Temperature
Package (2)
Ordering Code (3)
Industrial
(-40C to 85C) (4)
6ST1
ATtiny10-TSHR (5)
12 MHz
8MA4
ATtiny10-MAHR (6)
6ST1
ATtiny10-TS8R (5)
1.8 – 5.5V
10 MHz
Notes:
Extended
(-40C to 125C) (6)
1. For speed vs. supply voltage, see section 16.3 “Speed” on page 116.
2. All packages are Pb-free, halide-free and fully green and they comply with the European directive for Restriction of Hazardous Substances (RoHS). NiPdAu finish.
3. Tape and reel.
4. Can also be supplied in wafer form. Contact your local Atmel sales office for ordering information and minimum quantities.
5. Top/bottomside markings:
– Top: T10x, where x = die revision
– Bottom: zHzzz or z8zzz, where H = (-40C to 85C), and 8 = (-40C to 125C)
6. For typical and Electrical characteristics for this device please consult Appendix A, ATtiny4/5/9/10 Specification at 125°C.
Package Type
6ST1
6-lead, 2.90 x 1.60 mm Plastic Small Outline Package (SOT23)
8MA4
8-pad, 2 x 2 x 0.6 mm Plastic Ultra Thin Dual Flat No Lead (UDFN)
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21. Packaging Information
21.1
6ST1
D
5
6
E
E1
A
4
A2
Pin #1 ID
A1
3
2
b
0.10 C
SEATING PLANE
A
1
A
C
Side View
e
Top View
A2
A
0.10 C
SEATING PLANE
c
0.25
O
C
A1
C
View A-A
SEATING PLANE
SEE VIEW B
L
View B
COMMON DIMENSIONS
(Unit of Measure = mm)
SYMBOL MIN
Notes: 1. This package is compliant with JEDEC specification MO-178 Variation AB
2. Dimension D does not include mold Flash, protrusions or gate burrs.
Mold Flash, protrustion or gate burrs shall not exceed 0.25 mm per end.
3. Dimension b does not include dambar protrusion. Allowable dambar
protrusion shall not cause the lead width to exceed the maximum
b dimension by more than 0.08 mm
4. Die is facing down after trim/form.
MAX
NOM
A
–
–
1.45
A1
0
–
0.15
A2
0.90
–
1.30
D
2.80
2.90
3.00
E
2.60
2.80
3.00
E1
1.50
1.60
1.75
L
0.30
0.45
0.55
e
NOTE
2
0.95 BSC
b
0.30
–
0.50
c
θ
0.09
–
0.20
0°
–
8°
3
6/30/08
Package Drawing Contact:
[email protected]
TITLE
6ST1, 6-lead, 2.90 x 1.60 mm Plastic Small Outline
Package (SOT23)
GPC
TAQ
DRAWING NO.
REV.
6ST1
A
ATtiny4/5/9/10 [DATASHEET]
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21.2
8MA4
8
7
6
8x
5
0.05 c
c
0.05 c
E
SIDE VIEW
Pin 1 ID
1
2
3
4
D
A1
TOP VIEW
A
D2
e
8
5
COMMON DIMENSIONS
(Unit of Measure = mm)
K
E2
SYMBOL
MIN
NOM
MAX
A
–
–
0.60
A1
0.00
–
0.05
b
0.20
–
0.30
D
1.95
2.00
2.05
D2
1.40
1.50
1.60
E
1.95
2.00
2.05
E2
C0.2
4
1
L
b
BOTTOM VIEW
0.80
0.90
1.00
e
–
0.50
–
L
0.20
0.30
0.40
K
0.20
–
–
NOTE
Note: 1. ALL DIMENSIONS ARE IN mm. ANGLES IN DEGREES.
2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE
TERMINALS COPLANARITY SHALL NOT EXCEED 0.05 mm.
3. WARPAGE SHALL NOT EXCEED 0.05 mm.
4. REFER JEDEC MO-236/MO-252
TITLE
Package Drawing Contact:
[email protected]
8PAD, 2x2x0.6 mm body, 0.5 mm pitch,
0.9x1.5 mm exposed pad, Saw singulated
Thermally enhanced plastic ultra thin dual flat
no lead package (UDFN/USON)
GPC
YAG
12/17/09
DRAWING NO. REV.
8MA4
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157
22. Errata
The revision letters in this section refer to the revision of the corresponding ATtiny4/5/9/10 device.
22.1
ATtiny4
22.1.1
Rev. E
• Programming Lock Bits
1. Programming Lock Bits
Programming Lock Bits to a lock mode equal or lower than the current causes one word of Flash to be corrupted. The location of the corruption is random.
Problem Fix / Workaround
When programming Lock Bits, make sure lock mode is not set to present, or lower levels.
22.1.2
Rev. D
• ESD HBM (ESD STM 5.1) level ±1000V
• Programming Lock Bits
1. ESD HBM (ESD STM 5.1) level ±1000V
The device meets ESD HBM (ESD STM 5.1) level ±1000V.
Problem Fix / Workaround
Always use proper ESD protection measures (Class 1C) when handling integrated circuits before and during
assembly.
2. Programming Lock Bits
Programming Lock Bits to a lock mode equal or lower than the current causes one word of Flash to be corrupted. The location of the corruption is random.
Problem Fix / Workaround
When programming Lock Bits, make sure lock mode is not set to present, or lower levels.
22.1.3
Rev. A – C
Not sampled.
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22.2
ATtiny5
22.2.1
Rev. E
• Programming Lock Bits
1. Programming Lock Bits
Programming Lock Bits to a lock mode equal or lower than the current causes one word of Flash to be corrupted. The location of the corruption is random.
Problem Fix / Workaround
When programming Lock Bits, make sure lock mode is not set to present, or lower levels.
22.2.2
Rev. D
• ESD HBM (ESD STM 5.1) level ±1000V
• Programming Lock Bits
1. ESD HBM (ESD STM 5.1) level ±1000V
The device meets ESD HBM (ESD STM 5.1) level ±1000V.
Problem Fix / Workaround
Always use proper ESD protection measures (Class 1C) when handling integrated circuits before and during
assembly.
2. Programming Lock Bits
Programming Lock Bits to a lock mode equal or lower than the current causes one word of Flash to be corrupted. The location of the corruption is random.
Problem Fix / Workaround
When programming Lock Bits, make sure lock mode is not set to present, or lower levels.
22.2.3
Rev. A – C
Not sampled.
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22.3
ATtiny9
22.3.1
Rev. E
• Programming Lock Bits
1. Programming Lock Bits
Programming Lock Bits to a lock mode equal or lower than the current causes one word of Flash to be corrupted. The location of the corruption is random.
Problem Fix / Workaround
When programming Lock Bits, make sure lock mode is not set to present, or lower levels.
22.3.2
Rev. D
• ESD HBM (ESD STM 5.1) level ±1000V
• Programming Lock Bits
1. ESD HBM (ESD STM 5.1) level ±1000V
The device meets ESD HBM (ESD STM 5.1) level ±1000V.
Problem Fix / Workaround
Always use proper ESD protection measures (Class 1C) when handling integrated circuits before and during
assembly.
2. Programming Lock Bits
Programming Lock Bits to a lock mode equal or lower than the current causes one word of Flash to be corrupted. The location of the corruption is random.
Problem Fix / Workaround
When programming Lock Bits, make sure lock mode is not set to present, or lower levels.
22.3.3
Rev. A – C
Not sampled.
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22.4
ATtiny10
22.4.1
Rev. E
• Programming Lock Bits
1. Programming Lock Bits
Programming Lock Bits to a lock mode equal or lower than the current causes one word of Flash to be corrupted. The location of the corruption is random.
Problem Fix / Workaround
When programming Lock Bits, make sure lock mode is not set to present, or lower levels.
22.4.2
Rev. C – D
• ESD HBM (ESD STM 5.1) level ±1000V
• Programming Lock Bits
1. ESD HBM (ESD STM 5.1) level ±1000V
The device meets ESD HBM (ESD STM 5.1) level ±1000V.
Problem Fix / Workaround
Always use proper ESD protection measures (Class 1C) when handling integrated circuits before and during
assembly.
2. Programming Lock Bits
Programming Lock Bits to a lock mode equal or lower than the current causes one word of Flash to be corrupted. The location of the corruption is random.
Problem Fix / Workaround
When programming Lock Bits, make sure lock mode is not set to present, or lower levels.
22.4.3
Rev. A – B
Not sampled.
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23. Datasheet Revision History
23.1
Rev. 8127F – 02/13
1. Updated:
– Ordering information on page 152, page 153, page 154, and page 155
23.2
Rev. 8127E – 11/11
1. Updated:
– Device status from Preliminary to Final
– Ordering information on page 152, page 153, page 154, and page 155
23.3
Rev. 8127D – 02/10
1. Added UDFN package in “Features” on page 1, “Pin Configurations” on page 2, “Ordering Information” on
page 152, and in “Packaging Information” on page 156
2. Updated Figure 8-2 and Figure 8-3 in Section 8.2.1 “Power-on Reset” on page 27
3. Updated Section 8.2.3 “External Reset” on page 29
4. Updated Figures 17-36 and 17-51 in “Typical Characteristics”
5. Updated notes in Section 20. “Ordering Information” on pages 152 - 155
6. Added device Rev. E in Section 22. “Errata” on page 158
23.4
Rev. 8127C – 10/09
1. Updated values and notes:
– Table 16-1 in Section 16.2 “DC Characteristics” on page 115
– Table 16-3 in Section 16.4 “Clock Characteristics” on page 117
– Table 16-6 in Section 16.5.2 “VCC Level Monitor” on page 118
– Table 16-9 in Section 16.8 “Serial Programming Characteristics” on page 120
2. Updated Figure 16-1 in Section 16.3 “Speed” on page 116
3. Added Typical Characteristics Figure 17-36 in Section 17.8 “Analog Comparator Offset” on page 139.
Also, updated some other plots in Typical Characteristics.
4. Added topside and bottomside marking notes in Section 20. “Ordering Information” on page 152, up to
page 155
5. Added ESD errata, see Section 22. “Errata” on page 158
6. Added Lock bits re-programming errata, see Section 22. “Errata” on page 158
23.5
Rev. 8127B – 08/09
1. Updated document template
2. Expanded document to also cover devices ATtiny4, ATtiny5 and ATtiny9
3. Added section:
– “Comparison of ATtiny4, ATtiny5, ATtiny9 and ATtiny10” on page 4
4. Updated sections:
– “ADC Clock – clkADC” on page 18
– “Starting from Idle / ADC Noise Reduction / Standby Mode” on page 20
– “ADC Noise Reduction Mode” on page 24
– “Analog to Digital Converter” on page 25
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– “SMCR – Sleep Mode Control Register” on page 25
– “PRR – Power Reduction Register” on page 26
– “Alternate Functions of Port B” on page 48
– “Overview” on page 82
– “Physical Layer of Tiny Programming Interface” on page 95
– “Overview” on page 106
– “ADC Characteristics (ATtiny5/10, only)” on page 119
– “Supply Current of I/O Modules” on page 121
– “Register Summary” on page 148
– “Ordering Information” on page 152
5. Added figure:
– “Using an External Programmer for In-System Programming via TPI” on page 96
6. Updated figure:
– “Data Memory Map (Byte Addressing)” on page 15
7. Added table:
– “Number of Words and Pages in the Flash (ATtiny4/5)” on page 108
8. Updated tables:
– “Active Clock Domains and Wake-up Sources in Different Sleep Modes” on page 23
– “Reset and Interrupt Vectors” on page 35
– “Number of Words and Pages in the Flash (ATtiny9/10)” on page 107
– “Signature codes” on page 109
23.6
Rev. 8127A – 04/09
1. Initial revision
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Table of Contents
Features ..................................................................................................... 1
1
Pin Configurations ................................................................................... 2
1.1
2
Overview ................................................................................................... 3
2.1
3
4
5
6
7
Pin Description ..................................................................................................2
Comparison of ATtiny4, ATtiny5, ATtiny9 and ATtiny10 ....................................4
General Information ................................................................................. 5
3.1
Resources .........................................................................................................5
3.2
Code Examples .................................................................................................5
3.3
Capacitive Touch Sensing .................................................................................5
3.4
Data Retention ...................................................................................................5
CPU Core ................................................................................................... 6
4.1
Architectural Overview .......................................................................................6
4.2
ALU – Arithmetic Logic Unit ...............................................................................7
4.3
Status Register ..................................................................................................7
4.4
General Purpose Register File ..........................................................................7
4.5
Stack Pointer .....................................................................................................9
4.6
Instruction Execution Timing .............................................................................9
4.7
Reset and Interrupt Handling ...........................................................................10
4.8
Register Description ........................................................................................11
Memories ................................................................................................. 14
5.1
In-System Re-programmable Flash Program Memory ....................................14
5.2
Data Memory ...................................................................................................14
5.3
I/O Memory ......................................................................................................16
Clock System .......................................................................................... 17
6.1
Clock Subsystems ...........................................................................................17
6.2
Clock Sources .................................................................................................18
6.3
System Clock Prescaler ..................................................................................19
6.4
Starting ............................................................................................................20
6.5
Register Description ........................................................................................21
Power Management and Sleep Modes ................................................. 23
7.1
Sleep Modes ....................................................................................................23
7.2
Power Reduction Register ...............................................................................24
7.3
Minimizing Power Consumption ......................................................................24
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7.4
8
9
Register Description ........................................................................................25
System Control and Reset ..................................................................... 27
8.1
Resetting the AVR ...........................................................................................27
8.2
Reset Sources .................................................................................................27
8.3
Watchdog Timer ..............................................................................................30
8.4
Register Description ........................................................................................32
Interrupts ................................................................................................. 35
9.1
Interrupt Vectors ..............................................................................................35
9.2
External Interrupts ...........................................................................................36
9.3
Register Description ........................................................................................37
10 I/O Ports .................................................................................................. 40
10.1
Overview ..........................................................................................................40
10.2
Ports as General Digital I/O .............................................................................41
10.3
Alternate Port Functions ..................................................................................45
10.4
Register Description ........................................................................................50
11 16-bit Timer/Counter0 ............................................................................ 52
11.1
Features ..........................................................................................................52
11.2
Overview ..........................................................................................................52
11.3
Clock Sources .................................................................................................54
11.4
Counter Unit ....................................................................................................55
11.5
Input Capture Unit ...........................................................................................56
11.6
Output Compare Units .....................................................................................58
11.7
Compare Match Output Unit ............................................................................60
11.8
Modes of Operation .........................................................................................61
11.9
Timer/Counter Timing Diagrams ......................................................................69
11.10
Accessing 16-bit Registers ..............................................................................70
11.11
Register Description ........................................................................................72
12 Analog Comparator ................................................................................ 80
12.1
Register Description ........................................................................................80
13 Analog to Digital Converter ................................................................... 82
13.1
Features ..........................................................................................................82
13.2
Overview ..........................................................................................................82
13.3
Operation .........................................................................................................82
13.4
Starting a Conversion ......................................................................................83
13.5
Prescaling and Conversion Timing ..................................................................84
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13.6
Changing Channel ...........................................................................................87
13.7
ADC Noise Canceler .......................................................................................87
13.8
Analog Input Circuitry ......................................................................................88
13.9
Noise Canceling Techniques ...........................................................................88
13.10
ADC Accuracy Definitions ...............................................................................89
13.11
ADC Conversion Result ...................................................................................91
13.12
Register Description ........................................................................................92
14 Programming interface .......................................................................... 95
14.1
Features ..........................................................................................................95
14.2
Overview ..........................................................................................................95
14.3
Physical Layer of Tiny Programming Interface ................................................95
14.4
Access Layer of Tiny Programming Interface ..................................................99
14.5
Instruction Set ................................................................................................100
14.6
Accessing the Non-Volatile Memory Controller .............................................103
14.7
Control and Status Space Register Descriptions ...........................................103
15 Memory Programming ......................................................................... 106
15.1
Features ........................................................................................................106
15.2
Overview ........................................................................................................106
15.3
Non-Volatile Memories ..................................................................................106
15.4
Accessing the NVM .......................................................................................109
15.5
Self programming ..........................................................................................112
15.6
External Programming ...................................................................................112
15.7
Register Description ......................................................................................114
16 Electrical Characteristics .................................................................... 115
16.1
Absolute Maximum Ratings* .........................................................................115
16.2
DC Characteristics .........................................................................................115
16.3
Speed ............................................................................................................116
16.4
Clock Characteristics .....................................................................................117
16.5
System and Reset Characteristics ................................................................118
16.6
Analog Comparator Characteristics ...............................................................119
16.7
ADC Characteristics (ATtiny5/10, only) .........................................................119
16.8
Serial Programming Characteristics ..............................................................120
17 Typical Characteristics ........................................................................ 121
17.1
Supply Current of I/O Modules ......................................................................121
17.2
Active Supply Current ....................................................................................122
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17.3
Idle Supply Current ........................................................................................125
17.4
Power-down Supply Current ..........................................................................127
17.5
Pin Pull-up .....................................................................................................128
17.6
Pin Driver Strength ........................................................................................131
17.7
Pin Threshold and Hysteresis ........................................................................135
17.8
Analog Comparator Offset .............................................................................139
17.9
Internal Oscillator Speed ...............................................................................140
17.10
VLM Thresholds ............................................................................................142
17.11
Current Consumption of Peripheral Units ......................................................144
17.12
Current Consumption in Reset and Reset Pulsewidth ...................................147
18 Register Summary ................................................................................ 148
19 Instruction Set Summary ..................................................................... 150
20 Ordering Information ........................................................................... 152
20.1
ATtiny4 ..........................................................................................................152
20.2
ATtiny5 ..........................................................................................................153
20.3
ATtiny9 ..........................................................................................................154
20.4
ATtiny10 ........................................................................................................155
21 Packaging Information ......................................................................... 156
21.1
6ST1 ..............................................................................................................156
21.2
8MA4 .............................................................................................................157
22 Errata ..................................................................................................... 158
22.1
ATtiny4 ..........................................................................................................158
22.2
ATtiny5 ..........................................................................................................159
22.3
ATtiny9 ..........................................................................................................160
22.4
ATtiny10 ........................................................................................................161
23 Datasheet Revision History ................................................................. 162
23.1
Rev. 8127F – 02/13 .......................................................................................162
23.2
Rev. 8127E – 11/11 .......................................................................................162
23.3
Rev. 8127D – 02/10 .......................................................................................162
23.4
Rev. 8127C – 10/09 .......................................................................................162
23.5
Rev. 8127B – 08/09 .......................................................................................162
23.6
Rev. 8127A – 04/09 .......................................................................................163
Table of Contents ...................................................................................... 1
Features1 1
Table of Contents1 4
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Atmel Corporation
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© 2013 Atmel Corporation. All rights reserved. / Rev.: 8127F–AVR–02/2013
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