Atmel AVR ATtiny15L User Manual

Features

(

PDIP/SOIC

• High-performance, Low-power AVR

• Advanced RISC Architecture

– 90 Powerful Instructions – Most Single Clock Cycle Execution – 32 x 8 General Purpose Working Registers – Fully Static Operation

• Non-volatile Program and Data Memories

– 1K Byte In-System Programmable Flash Program Memory

Endurance: 1,000 Write/Erase Cycles

– 64 Bytes EEPROM

Endurance: 100,000 Write/Erase Cycles

– Programming Lock for Flash Program Data Security

• Peripheral Features

– Interrupt and Wake-up on Pin Change – Two 8-bit Timer/Counters with Separate Prescalers – One 150 kHz, 8-bit High-speed PWM Output – 4-channel 10-bit ADC

One Differential Voltage Input with Optional Gain of 20x – On-chip Analog Comparator – Programmable Watchdog Timer with On-chip Oscillator

• Special Microcontroller Features

– In-System Programmable via SPI Port – Enhanced Power-on Reset Circuit – Programmable Brown-out Detection Circuit – Internal, Calibrated 1.6 MHz Tunable Oscillator – Internal 25.6 MHz Clock Generator for Timer/Counter – External and Internal Interrupt Sources – Low-power Idle and Power-down Modes

• Power Consumption at 1.6 MHz, 3V, 25°C

– Active: 3.0 mA – Idle Mode: 1.0 mA – Power-down: < 1 µA

• I/O and Packages

– 8-lead PDIP and 8-lead SOIC: 6 Programmable I/O Lines

• Operating Voltages

– 2.7V - 5.5V

• Internal 1.6 MHz System Clock

8-bit Microcontroller

8-bit Microcontroller with 1K Byte Flash

ATtiny15L

Pin Configuration

RESET/ADC0) PB5

(ADC3) PB4 (ADC2) PB3

GND

1 2 3 4

VCC

PB2 (ADC1/SCK/T0/INT PB1 (AIN1/MISO/OC1A)

PB0 (AIN0/AREF/MOSI)

Not recommended for new design

Rev. 1187H–AVR–09/07

Description The ATtiny15L is a low-power CMOS 8-bit microcontroller based on the AVR RISC

architecture. By executing powerful instructions in a single clock cycle, the ATtiny15L achieves throughputs approaching 1 MIPS per MHz allowing the system designer to optimize power consumption versus processing speed.

The AVR core combines a rich instruction set with 32 general purpose working registers. All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers to be accessed in one single instruction executed in one clock cycle. The resulting architecture is more code ef ficient while a chieving th roughputs up to ten times faster than conventional CISC microcontrollers.

The ATtiny15L provides 1K byte of Flash, 64 bytes EEPROM, six general purpose I/O lines, 32 general purpose working registers, two 8-bit Timer/Counters, one with highspeed PWM output, internal Oscillators, internal and external interrupts, programmable Watchdog Timer, 4-channel 10-bit Analog-to-Digital Converter with one differential voltage input with optional 20x gain, and three software-selectable Power-saving mod es. The Idle mode stops the CPU while allowing the ADC, anAlog Comparator, Timer/Counters and interrupt system to continue fu nctio ning. The ADC No ise Re du ct ion mode facilitates high-accuracy ADC measurements by stopping the CPU while allowing the ADC to continue functioning. The Po wer- down mo de saves t he reg ist er co ntent s b ut freezes the Oscillators, disabling all other chip functions until the next interrupt or Hardware Reset. The wake-up or interrupt on pin change features enable the ATtiny15L to be highly responsive to external events, still featuring the lowest power consumption while in the Power-saving modes.

The device is manufactured using Atmel’s high-density, Non-volatile memory technology. By combining a RISC 8-bit CPU with Flash on a monolithic chip, the ATtiny15L is a powerful microcontroller that provides a highly flexible and cost-efficient solution to many embedded control applications. The peripheral features make the ATtiny15L particularly suited for battery chargers, lighting ballasts and all kinds of intelligent sensor applications.

The ATtiny15L AVR is supported with a full suite of program and system development tools including macro assemblers, program debugger/simulators, In-circuit emulators and evaluation kits.

ATtiny15L

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Block Diagram Figure 1. The ATtiny15L Block Diag ram

VCC

ATtiny15L

GND

PROGRAM COUNTER

PROGRAM

FLASH

INSTRUCTION

DECODER

CONTROL

LINES

PROGRAMMING

LOGIC

STACK

POINTER

HARDWARE

STACK

GENERAL PURPOSE

REGISTERS

ALU

STATUS

ISP MODULE

8-BIT DATA BUS

INTERNAL

TOR

OSCILLA

WATCHDOG

TIMER

MCU CONTROL

MCU STATUS

TIMER/

COUNTER0

TIMER/

COUNTER1

INTERRUPT

UNIT

DATA

EEPROM

TUNABLE

INTERNAL

TOR

OSCILLA

TIMING AND

CONTROL

DATA REGISTER

PORT B

ANALOG

COMPARATOR

DATA DIR.

REG.PORT B

PORT B DRIVERS

PB0-PB5

ANALOG MUX ADC

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Pin Descriptions

VCC Supply voltage pin. GND Ground pin. Port B (PB5..PB0) Port B is a 6-bit I/O port. PB4..0 are I/O pins that can provide internal pull-ups (selected

for each bit). PB5 is input or open-drain output. The use of pin PB5 is defined by a fuse and the special function associated with this pin is External Reset. The port pins are tristated when a reset condition becomes active, even if the clock is not running.

Port B also accommodates analog I/O pins. The Port B pins with alternate functions are shown in Table 1.

Table 1. Port B Alternate Functions

Port Pin Alternate Function

PB0 MOSI (Data Input Line for Memory Downloading)

AREF (ADC Voltage Reference) AIN0 (Analog Comparator Positive Input)

PB1 MISO (Data Output Line for Memory Downloading)

OC1A (Timer/Counter PWM Output) AIN1 (Analog Comparator Negative Input)

PB2 SCK (Serial Clock Input for Serial Programming)

INT0 (External Interrupt0 Input) ADC1 (ADC Input Channel 1)

T0 (Timer/Counter0 External Counter Input) PB3 ADC2 (ADC Input Channel 2) PB4 ADC3 (ADC Input Channel 3) PB5 RESET

(External Reset Pin)

ADC0 (ADC Input Channel 0)

Analog Pins Up to four analog inputs can be selected as inputs to Analog-to-Digital Converter (ADC).

Internal Oscillators The internal Oscillator provides a clock rate of nominally 1.6 MHz for the system clock

(CK). Due to large initial variation (0.8 -1.6 MHz) of the internal Oscillator, a tuning cap ability is built in. Through an 8-bit control register – OSCCAL – the system clock rate can be tuned with less than 1% steps of the nominal clock.

There is an internal PLL that provides a 16x clock rate locked to the system clock (CK) for the use of the Peripheral Timer/Counter1. The nominal frequency of this peripheral clock, PCK, is 25.6 MHz.

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ATtiny15L

ATtiny15L Architectural Overview

The fast-access Register File concept contains 32 x 8-bit general purpose working registers with a single-clock-cycle access time. This means that during one single clock cycle, one ALU (Arithmetic Logic Unit) operation is executed. Two operands are output from the Register File, the operation is executed, and the result is stored back in the Register File – in one clock cycle.

Two of the 32 registers can be used as a 16-bit pointer for indir ect memo ry access. T his pointer is called the Z-pointer, and can address the Register File, IO file and the Flash Program memory.

Figure 2. The ATtiny15L AVR RISC Architecture

Data Bus 8-bit

Control

Registrers

Interrupt

Unit

SPI Unit

2 x 8-bit

Timer/Counter

Watchdog

Timer

ADC

512 x 16 Program

FLASH

Instruction

Decoder

Control Lines

Program

Counter

Direct Addressing

Status

and Test

32 x 8

General

Purpose

Registrers

ALU

64 x 8

EEPROM

Analog

Comparator

I/O Lines

The ALU supports arithmetic and logic functions between registers or between a constant and a register. Single-register operations are also executed in the ALU. Figure 2 shows the ATtiny15L AVR RISC microcontroller architecture. The AVR uses a Harvard architecture concept with separate memories and buses for program and data memories. The program memory is accessed with a two-stage pipeline. While one instruction is being executed, the next instruction is pre-fetched from the program memory. This concept enables instructions to be executed in every clock cycle. The Program memory is In-System Programmable Flash memory.

With the relative jump and relative call instructions, the whole address space is directly accessed. All AVR instructions have a single 16-bit word format, meaning that every program memory address contains a single 16-bit instruction .

During interrupts and subroutine calls, the return address Program Counter (PC) is stored on the Stack. The Stack is a 3-level-deep Hardware Stack dedicated for subroutines and interrupts.

The I/O memory space contains 64 addresses for CPU peripheral functions as Control Registers, Timer/Counters and other I/O functions. The memory spaces in the AVR architecture are all linear and regular memory maps.

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A flexible interrupt module has its control registers in the I/O space with an additional Global Interrupt Enable bit in the Status Regist er. All the dif fere nt interru pts ha ve a separate Interrupt Vector in the Interrupt Vector table at the be ginning of the program memory. The different interrupts have priority in accordance with their Interrupt Vector position. The lower the Interrupt Vector addr es s, th e hig he r th e pr ior i ty.

The General Purpose Register File

Figure 3 shows the structure of the 32 general purpose registers in the CPU. Figure 3. AVR CPU General Purpose Working Registers

R0 R1 R2

General …

Purpose …

Working R28

Registers R29

R30 (Z-register Low Byte)R3

R31 (Z-register High Byte)

All the register operating instructions in the instruction set have direct- and single-cycle access to all registers. The only exception is the five constant arithmetic and logic instructions SBCI, SUBI, CPI, ANDI, and ORI between a constant and a reg ister and the LDI instruction for load-immediate constant d ata. T hese in str uctions a ppl y to th e second half of the registers in the Register File – R16..R31. The general SBC, SUB, CP, AND, OR, and all other operations between two registers or on a single -register apply to the entire Register File.

Registers 30 and 31 form a 16-bit pointer (the Z-point er) which is used for indirect Flash memory and Register File access. When the Register File is accessed, the contents of R31 is discarded by the CPU.

The ALU – Arithmetic Logic Unit

The Flash Program Memory

ATtiny15L

The high-performance AVR ALU operates in di rect connection with all th e 32 general purpose working registers. Within a single clock cycle, ALU operations between registers in the Register File are executed. T he ALU operations are div ided into three main categories – arithmetic, logic a nd bit-funct ions. Some microcon trollers in the AVR prod uct family feature a hardware multiplier in the arithmetic part of the ALU.

The ATtiny15L contains 1K byte On-chip, In-System Programmable Flash memory for program storage. Since all instructions are single 16-bit words, the Flash is organized as 512 x 16 words. The Flash memory has an endurance of at least 1,000 write/erase cycles.

The ATtiny15L Program Counter is nine bits wide, thus addressing the 512 words Flash Program memory.

See page 54 for a detailed description on Flash memory programming.

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ATtiny15L

The Program and Data Addressing Modes

The ATtiny15L AVR RISC Microcontroller supports powerful and efficient addressing modes. This section describes the various addressing modes supported in the ATtiny15L. In the figures, OP means the operation code part of the instruction word. To simplify, not all figures show the exact location of the add ressin g bit s.

Figure 4. Direct Single-register Addressing

The operand is contained in register d (Rd).

Register Indirect Figure 5. Indirect Register Addressing

Register Direct, T wo Register s Rd and Rr

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Z-register

The register accessed is the one pointed to by the Z-register low byte (R30).

Figure 6. Direct Register Addressing, Two Registers

Operands are contained in register r (Rr) and d (Rd). The result is stored in register d

$1FF

(Rd).

I/O Direct Figure 7. I/O Direct Addressing

Operand address is contained in 6 bits of the instru ction word. “n” is the destina tion or source register address.

Relative Program Addressing, RJMP and RCALL

Constant Addressing using the LPM Instruction

Figure 8. Relative Program Memory Addressing

Program execution continues at address PC + k + 1. The relative address k is -2048 to

2047.

Figure 9. Code Memory Constant Addressing

ATtiny15L

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ATtiny15L

T1 T2 T3 T4

Constant byte address is specified by the Z-register contents. The 15 MSBs select word address (0 - 511), and LSB selects low byte if cleared (LSB = 0) or high byte if set (LSB = 1).

Subroutine and Interrupt Hardware Stack

The EEPROM Data Memory

Memory Access and Instruction Execution Timing

The ATtiny15L uses a 3-level-deep Hardware Stack for subroutines and interrupts. The Hardware Stack is nine bits wide and stores the Program Counter (PC) return ad dress while subroutines and interrupts are executed.

RCALL instructions and interrupts push the PC return address onto Stack level 0, and the data in the other Stack levels 1 - 2 are pushed one level deeper in the Stack. When a RET or RETI instruction is executed the returning PC is fetched from Stack level 0, and the data in the other Stack levels 1 - 2 are popped one level in the Stack.

If more than three subsequent subroutine calls or interrupts are execute d, the first values written to the Stack are overwritten. Pushing four return addresses A1, A2, A3, and A4 followed by four subroutine or interrupt returns, will pop A4, A3, A2, and once more A2 from the Hardware Stack.

The ATtiny15L contains 64 bytes of data EEPROM memory. It is organized as a separate data space, in which single bytes can be read and written. The EEPROM has an endurance of at least 100,000 write/erase cycles. The access between the EEPROM and the CPU is described on page 36, specifying the EEPROM Address Register, the EEPROM Data Register, and the EEPROM Control Register.

This section describes the general access timing concepts for instruction execution and internal memory access.

The AVR CPU is driven by the System Clock Ø, directly generated from the external clock crystal for the chip. No internal clock division is used.

Figure 10 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 corre sponding unique result s for functions per cost, functions per clocks, and functions per power-unit.

Figure 10. The Parallel Instruction Fetches and Instruction Executions

System Clock Ø

1st Instruction Fetch

1st Instruction Execute

2nd Instruction Fetch

nd Instruction Execute

3rd Instruction Fetch

3rd Instruction Execute

4th Instruction Fetch

Figure 11 shows the internal timing concept for the Register File. In a single clock cycle an ALU operation using two register operands is execu ted, and the result is stored back to the destination register.

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Figure 11. Single Cycle ALU Operation

T1 T2 T3 T4

System Clock Ø

Total Execution Time egister Operands Fetch ALU Operation Execute

Result Write Back

I/O Memory The I/O space definition of the ATtiny15L is shown in Table 2.

Table 2. ATtiny15L I/O Space

Address Hex Name Function

$3F SREG Status Register $3B GIMSK General Interrupt Mask Register $3A GIFR General Interrupt Flag Register $39 TIMSK Timer/Counter Interrupt Mask Register $38 TIFR Timer/Counter Interrupt Flag Register $35 MCUCR MCU Control Register $34 MCUSR MCU Status Register $33 TCCR0 Timer/Counter0 Control Register $32 TCNT0 Timer/Counter0 (8-bit) $31 OSCCAL Oscillator Calibration Register $30 TCCR1 Timer/Counter1 Control Register $2F TCNT1 Timer/Counter1 (8-bit) $2E OCR1A Timer/Counter1 Output Compare Register A $2D OCR1B Timer/Counter1 Output Compare Register B $2C SFIOR Special Function I/O Register

(1)

$21 WDTCR Watchdog Timer Control Register $1E EEAR EEPROM Address Register $1D EEDR EEPROM Data Register $1C EECR EEPROM Control Register $18 PORTB Data Register, Port B $17 DDRB Data Direction Register, Port B $16 PINB Input Pins, Port B $08 ACSR Analog Comparator Control and Status Register $07 ADMUX ADC Multiplexer Select Register

ATtiny15L

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ATtiny15L

Table 2. ATtiny15L I/O Space

Address Hex Name Function

$06 ADCSR ADC Control and Status Register $05 ADCH ADC Data Register High $04 ADCL ADC Data Register Low

Note: 1. Reserved and unused locations are not shown in the table.

(1)

(Continued)

All ATtiny15L I/O and peripheral registers are placed in the I/O space. The I/O locations are accessed by the IN and OUT instructions transferring data between the 32 general purpose working registers and the I/O space. I/O Registers within the address range $00 - $1F are directly bit-accessible using the SBI and CBI instructions. In these registers, the value of single bits can be checked by using the SBIS and SBIC instructions. Refer to the instruction set chapter for more details. For compatibility with future devices, reserved bits should be written zero if accessed. Reserved I/O memory addresses should never be written.

The I/O and Peripheral Control Registers are explained in the following sections.

The Status Register – SREG The AVR Status Register – SREG – at I/O space location $3F is defined as:

Bit 76543210 $3F I T H S V N Z C SREG Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0

• Bit 7 – I: Global Interrupt Enable

The Global Interrupt Enable bit must be set (one ) for the interrupts to be enabled. The individual interrupt enable control is then performed in the Interrupt Ma sk Registers – GIMSK and TIMSK. If the Global Interr up t Enab le Reg ist e r is clea red ( ze ro ), n one of t he interrupts are enabled independent of the GIMSK and TIMSK va lues. The I-bit is clear ed by hardware after an interrupt has occurred, and is set by the RET I inst ruct ion to en able subsequent interrupts.

• Bit 6 – T: Bit Copy Storage

The Bit Copy instructions BLD (Bit LoaD) and BST (Bit STore) use the T-bit as source and destination for the operated bit. A bit fr om a re gister in th e Reg ist er File ca n be co pied into T by the BST instruction, and a bit in T can be copied in to a bit in a r egister in the Register File by the BLD instruction.

• Bit 5 – H: Half-carry Flag

The Half-carry Flag H indicates a half-carry in some arithmetic operations. See the Instruction Set description for detailed information.

• Bit 4 – S: Sign Bit, S = N ⊕ V

The S-bit is always an exclusive or between the Negative Flag N and the Two’s Complement Overflow Flag V. See the Instruction Set description for detailed information.

• Bit 3 – V: Two’s Complement Overflow Flag

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The Two’s Complement Overflow Flag V supports two’s complement arithmetics. See the Instruction Set description for detailed information.

• Bit 2 – N: Negative Flag

The Negative Flag N indicates a negative result after the different arithmetic and logic operations. See the Instruction Set description for detailed information.

• Bit 1 – Z: Zero Flag

The Zero Flag Z indicates a zero result after the different arithmetic and logic operations. See the Instruction Set description for detailed information.

• Bit 0 – C: Carry Flag

The Carry Flag C indicates a carry in an arithmetic or logic o peration. See th e Instruction Set description for detailed information.

Reset and Interrupt Handling

The ATtiny15L provides eight interrupt sources. These interrupts and the separate Reset Vector each have a separate Program Vector in the Program memory space. All the interrupts are assigned individual enable bits th at must be set (one) together wit h the I-bit in the Status Register in order to enable the inter rupt.

The lowest addresses in the Program memory space are automatically defined as the Reset and Interrupt Vectors. The complete list of vectors is shown in Table 3. The list also determines the priority levels of the different interrupts. The lower the address the higher is the priority level. RESET has the highest priority, and next is INT0 (the External Interrupt Request 0), etc.

Table 3. Reset and Interrupt Vectors

Vector No. Program Address Source Interrupt Definition

1 $000 RESET External Reset, Power-on Reset,

Brown-out Reset, and Watchdog

Reset 2 $001 INT0 External Interru pt Request 0 3 $002 I/O Pins Pin Change Interrupt 4 $003 TIMER1, COMPA Timer/Counter1 Compare Match A 5 $004 TIMER1, OVF Timer/Counter1 Overflow 6 $005 TIMER0, OVF Timer/Counter0 Overflow 7 $006 EE_RDY EEPROM Ready

8 $007 ANA_COMP Analog Comparator 9 $008 ADC ADC Conversion Complete

ATtiny15L

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The most typical and general program setup for the Reset and Interrupt Vector Addresses are:

Address Labels Code Comments

$000 rjmp RESET ; Reset handler

$001 rjmp EXT_INT0 ; IRQ0 handler

$002 rjmp PIN_CHANGE ; Pin change handler

$003 rjmp TIM1_CMP ; Timer1 compare match

$004 rjmp TIM1_OVF ; Timer1 overflow handler

$005 rjmp TIM0_OVF ; Timer0 overflow handler

$006 rjmp EE_RDY ; EEPROM Ready handler

$007 rjmp ANA_COMP ; Analog Comparator handler

$008 rjmp ADC ; ADC Conversion Handler

;

$009 MAIN: <instr> xxx ; Main program start

… … … …

ATtiny15L Reset Sources The ATtiny15L has four sources of Reset:

• Po wer-on Reset. The MCU is reset when the supply voltage is below the Power-on Reset threshold (V

POR

• External Reset. The MCU is reset when a low-level is present on the RESET more than 500 ns.

• Watchdog Reset. The MCU is reset when t he Watchdog Timer period expires, and the Watchdog is enabled.

• Brown-out Reset. The MCU is reset when the supply voltage V Brown-out Reset threshold (V

BOT

During Reset, all I/O Registers are then set to their initial values, and the program starts execution from address $000. The instructio n placed in ad dr ess $000 must be an 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 12 shows the reset logic. Table 4 and Table 5 define the timing and electrical parameters of the reset circuitry. Note that the Register File is unchanged by a reset.

ATtiny15L

pin for

is below the

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Figure 12. Reset Logic

Power-on Reset

Circuit

DATA BU S

MCU Status

BORF

PORF

WDRF

EXTRF

BODEN

BODLEVEL

Table 4. Reset Characteristics (VCC = 5.0V)

Brown-out

Reset Circuit

Watchdog

Timer

Watchdog Oscillator

Tunable Internal

Oscillator

CKSEL[1:0]

Delay Counters

TIMEOUT

(1)

Symbol Parameter Condition Min Typ Max Units

Pow er-on Reset Threshold Voltage (rising)

POT

RST

Pow er-on Reset Threshold Voltage (falling)

(1)

RESET Pin Threshold Voltage

BOD disabled 1.0 1.4 1.8 V

BOD enabled 1.7 2.2 2.7 V

BOD disabled 0.4 0.6 0.8 V

BOD enabled 1.7 2.2 2.7 V

– – 0.85 V

ATtiny15L

BOT

Brown-out Reset Threshold Voltage

(BODLEVEL = 1) 2.3 2.7 2.9 V (BODLEVEL = 0) 3.4 4.0 4.3 V

Note: 1. The Power-on Reset will not work unless the supply voltage has been below V

(falling).

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POT

ATtiny15L

Table 5. Reset Delay Selections

BODEN

Notes: 1. On Power-up, the start-up time is increased with typical 0.6 ms.

(2)

CKSEL [1:0]

x 00 256 ms + 18 CK 64 ms + 18 CK

x 01 256 ms + 18 CK 64 ms + 18 CK

x 10 16 ms + 18 CK 4 ms + 18 CK

1 11 18 CK + 32 µs 18 CK + 8 µs BOD disabled 0 11 18 CK + 128 µs 18 CK + 32 µs BOD enabled

2. “0” means programmed, “1” means unprogrammed.

(2)

(1)

Start-up Time,

at V

TOUT

= 2.7V

Start-up Time,

at V

TOUT

= 5.0V

Recommended Usage

BOD disabled, slowly rising power

BOD disabled, quickly rising power

Table 5 shows the start-up times from Reset. When the CPU wa kes up from Powerdown, only the clock-counting part of the start-up time is used. The Watchdog Oscillator is used for timing the real-time part of the start-up time. The number Watchdog Oscillator cycles used for each time-out is shown in Table 6.

The frequency of the Watchdog Oscillator is voltage dependent as shown in the Electrical Characteristics section on page 64. The device is shipped with CKSEL = “00”.

Table 6. Number of Watchdog Oscillator Cycles

VCC Conditions Time-out Number of Cycles

2.7V 32 µs 8

2.7V 128 µs 32

2.7V 16 ms 4K

2.7V 256 ms 64K

5.0V 8 µs 8

5.0V 32 µs 32

5.0V 4 ms 4K

5.0V 64 ms 64K

Pow er-on Reset A Power-on Reset (POR) pulse is generated by an On-chip Dete ction circuit . The det ec-

tion level is nominally defined in Table 4. The POR is activated whenever V

is below

the detection level. The POR circuit can be used to trigger the Start -up Reset, as well as detect a failure in supply voltage.

A Power-on Reset (POR) circuit ensures that the device is Reset from Power-on. Reaching the Power-on Reset threshold voltage invok es a delay counter, which determines the delay, for which the device is kept in RESET after V

rise. The Time-out

period of the delay counter can be defined by the user through the CKSEL Fuses. The different selections for the delay period are presented in Table 5. The RESET signal is activated again, without any delay, when the V

decreases below detection level.

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Figure 13. “MCU Start-up, RESET Tied to V

RESET

VCC

RESET

IME-OUT

NTERNAL

POT

RST

TOUT

Figure 14. MCU Start-up, RESET Extended Externally

VCC

RESET

IME-OUT

POT

RST

TOUT

NTERNAL

RESET

External Reset An External Reset is generated by a low-level on the RESET

than 500 ns will generate a reset, even if the clock is not running. Shorter pulses are not guaranteed to generate a reset. When the applied signal reaches the Reset Threshold Voltage (V period t

) on its positive edge, the delay timer starts the MCU after the Time-out

RST

has expired.

TOUT

Figure 15. External Reset during Operation

pin. Reset pulses longer

ATtiny15L

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ATtiny15L

Brown-out Detection ATtiny15L has an On-chip Brown-out Detection (BOD) circuit for monitoring the V

level during the operation. The BOD circuit can be enabled/disabled by the fuse BODEN. When BODEN is enabled (BODEN programmed), and V the trigger level, the Brown-out Reset is immediately activated. When V

decreases below

increases

above the trigger level, the Brown-out Reset is deactivated after a delay. The delay is defined by the user in the same way as the d elay of POR sig nal, in Tab le 5. The tr igger level for the BOD can be selected by the fuse BODLEVEL to be 2.7V (BODLEVEL unprogrammed), or 4.0V (BODLEVEL programmed). The trigger level has a hysteresis of 50 mV to ensure spike-free Brown-out Detection.

The BOD circuit will only detect a drop in V for longer than 3

µs for trigger level 4.0V, 7 µs for trigger level 2.7V (typical values).

Figure 16. Brown-out Reset during Operation

RESET

IME-OUT

NTERNAL

RESET

BOT-

if the voltage stays below the trigger level

(1)

BOT+

TOUT

Note: 1. The hysteresis on V

BOT

: V

BOT+

= V

+ 25 mV, V

BOT

BOT-

= V

- 25 mV.

BOT

Watchdog Reset When the Watchdog times out, it will generate a short reset pulse of one CK cycle dura-

tion. On the falling edge of this pulse, the delay timer starts cou nting the Time -out period t

. Refer to page 34 for details on operation of the Watchdog Timer.

TOUT

Figure 17. Watchdog Reset during Operation

1 CK Cycle

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MCU Status Register – MCUSR

The MCU Status Register provides information on which reset source caused an MCU Reset.

Bit 76543210 $34 ––––WDRFBORFEXTRFPORFMCUSR Read/WriteRRRRR/WR/WR/WR/W Initial Value0000 See Bit Description

• Bit 7..4 – Res: Reserved Bits

These bits are reserved bits in the ATtiny15L and always read as zero.

• Bit 3 – WDRF: Watchdog Reset Flag

This bit is set (one) if a Watchdog Reset occurs. The bit is reset (zero) by a Power-on Reset, or by writing a logical “0” to the flag.

• Bit 2 – BORF: Brown-out Reset Flag

This bit is set (one) if a Brown-out Reset occurs. The bit is reset (zero) by a Power-on Reset, or by writing a logical “0” to the flag.

• Bit 1 – EXTRF: External Reset Flag

This bit is set (one) if a External Reset occurs. The bit is reset (zero) by a Power-on Reset, or by writing a logical “0” to the flag.

Internal Voltage Reference

Voltage Reference Enable Signals and Start-up Time

• Bit 0 – PORF: Power-on Reset Flag

This bit is set (one) if a Power-on Reset occurs. The bit is reset (zero) by writing a logical “0” 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.

ATtiny15L features an internal bandgap reference with a nominal voltage of 1.22V. This reference is used for Brown-out Detection, and it can be used as an input to the Analog Comparator. The 2.56V reference to the ADC is generated from the internal bandgap reference.

The voltage reference has a start-up time that may influence the way it should be used. The maximum start-up time is 10 µs. To save power, the reference is not always turned on. The reference is on during the following situations:

1. When the BOD is enabled (by programming the BODEN Fuse).

2. When the bandgap reference is connected to the Analog Comparator ( b y settin g the AINBG bit in ACSR).

3. When the ADC is enabled.

Thus, when the BOD is not enabled, after setting the AINBG bit, the user must always allow the reference to start-up before the output from the Analog Comparator is used. The bandgap reference uses typic ally 10 µA, and to reduce power consumption in Power-down mode, the user can avoid the three condit ions above to ensure tha t the re ference is turned off before entering Power-down mode.

ATtiny15L

1187H–AVR–09/07

ATtiny15L

Interrupt Handling The ATtiny15L has two 8-bit Interrupt Mask Control Registers: GIMSK (General Inter-

rupt Mask Register) and TIMSK (Timer/Counter Interrupt Mask Register). When an interrupt occurs, the Global Int erru pt Enable I- bit is clear ed (ze ro) a nd all inte r-

rupts are disabled. The user software can set the I-bit (one) to enable interrupts. The Ibit is set (one) when a Return from Interrupt instruction (RETI) is executed.

When the Program Counter is vectored to the actual Interrupt Vector in order to execute the interrupt handling routine, hardware cl ears the correspo nding fla g that ge nerate d the interrupt. Some of the interrupt flags can also be cleared by writing a logical “1” to the flag bit position(s) to be cleared.

If an interrupt condition occurs when the corresp onding interrupt enable bit is cleared (zero), the interrupt flag will be set and remembered until the interrupt is enabled, or the flag is cleared by software.

If one or more interrupt conditions occur when the global interrupt enable bit is cleared (zero), the corresponding interrupt flag(s) will be set and remembered until the global interrupt enable bit is set (one), and will be executed by order of priority.

Note that external level interrupt does not have a flag, and will only be remembered for as long as the interrupt condition is present.

Note that the Status Register is not automatically stored when entering an interrupt routine and restored when returning from an interrupt routine. This must be handled by software.

Interrupt Response Time The interrupt execution response for all the enabled AVR interrupts is four clock cycles

minimum. After the four clock cycles the Program Vector address for the actual interrupt handling routine is executed. During this 4-clock-cycle period, the Program Counter (nine bits) is pushed onto the Stack. The vector is often a relative jump to the in terrupt routine, and this jump takes two clock cycles. If an interrupt occurs during execut ion 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.

A return from an interrupt handling routine takes four clock cycles. During these four clock cycles, the Program Counter (nine bits) is popped back from the Stack. When AVR exits from an interrupt, it will always return to the main program and execute one more instruction before any pending interrupt is served.

The General Interrupt Mask Register – GIMSK

Bit 76543210 $3B – INT0 PCIE – – – – – GIMSK Read/Write R R/W R/W R R R R R Initial Value 0 0 0 0 0 0 0 0

• Bit 7 – Res: Reserved Bit

This bit is a reserved bit in the ATtiny15L and always reads as zero.

• Bit 6 – INT0: External Interrupt Request 0 Enable

1187H–AVR–09/07

When the INT0 bit is set (one) and the I-bit in the Status Register (SREG) is set (one), the external pin interrupt is activated. The Interrupt Sense Control0 bits 1/0 (ISC01 and ISC00) in the MCU general Control Register (MCUCR) define whether the external interrupt is activated on rising or falling edge, on pin change, or low level of the INT0 pin. Activity on the pin will cause an interrupt request even if INT0 is configured as an output.

The corresponding interrupt of External Interrupt Request 0 is executed from Program memory address $001. See also “External Interrupts.”

• Bit 5 – PCIE: Pin Change Interrupt Enable

When the PCIE bit is set (one) and the I-bit in the Status Register (SREG) is set (one), the interrupt on pin change is enabled. Any change on any input or I/O pin will cause an interrupt. The corresponding interrupt of Pin Change Interrupt Request is executed from Program memory address $002. See also “Pin Change Interrupt.”

• Bits 4..0 – Res: Reserved Bits

These bits are reserved bits in the ATtiny15L and always read as zero.

The General Interrupt Flag Register – GIFR

Bit 76543210 $3A –INTF0PCIF–––––GIFR Read/Write R R/W R/W R R R R R Initial Value 0 0 0 0 0 0 0 0

• Bit 7 – Res: Reserved Bit

This bit is a reserved bit in the ATtiny15L and always reads as zero.

• Bit 6 – INTF0: External Interrupt Flag0

When an edge or logic change on the INT0 pin triggers an interrupt request, INTF0 becomes set (one). If the I-bit in SREG and the INT0 bit in GIMSK are set (one), the MCU will jump to the Interrupt Vector at address $001. The flag is cleared when the interrupt routine is executed. Alternatively, the flag can be cleared by writing a logical “1” to it. The flag is always cleared when INT0 is configured as level interrupt.

• Bit 5 – PCIF: Pin Change Interrupt Flag

When an event on any input or I/O pin triggers an interrupt request, PCIF becomes set (one). If the I-bit in SREG and the PCIE bit in GIMSK are set (one), the MCU will jump to the Interrupt Vector at address $002. The fla g is cleared when the interrupt ro utine is executed. Alternatively, the flag can be cleared by writing a logical “1” to it.

• Bits 4..0 – Res: Reserved Bits

The Timer/Counter Interrupt Mask Register – TIMSK

ATtiny15L

These bits are reserved bits in the ATtiny15L and always read as zero.

Bit 7 6 5 4 3 2 1 0 $39 – OCIE1A – – – TOIE1 TOIE0 – TIMSK Read/Write R R/W R R R R/W R/W R Initial Value 0 0 0 0 0 0 0 0

• Bit 7 – Res: Reserved Bit

This bit is a reserved bit in the ATtiny15L and always reads as zero.

• Bit 6 – OCIE1A: Timer/Counter1 Output Compare Interrupt Enable

When the OCIE1A bit is set (one) and the I-bit in the Status Register is set (one), the Timer/Counter1 Compare Match, interrupt is enabled. The corresponding interrupt (at

1187H–AVR–09/07

ATtiny15L

vector $003) is executed if a compare match A in Timer/Counter1 occurs, i.e., when the OCF1A bit is set (one) in the Timer/Counter Interrupt Flag Register (TIFR).

• Bit 5..3 – Res: Reserved Bits

These bits are reserved bits in the ATtiny15L and always read as zero.

• Bit 2 – TOIE1: Timer/Counter1 Overflow Interrupt Enable

When the TOIE1 bit is set (one) and the I-bit in the Status Register is set (one), the Timer/Counter1 Overflow interrupt is enabled. The corresponding interrupt (at vector $004) is executed if an overflow in Timer/Counter1 occurs, i.e. , when the TOV1 bit is set (one) in the Timer/Counter Interrupt Flag Regi ster (TIFR).

• Bit 1 – TOIE0: Timer/Counter0 Overflow Interrupt Enable

When the TOIE0 bit is set (one) and the I-bit in the Status Register is set (one), the Timer/Counter0 Overflow interrupt is enabled. The corresponding interrupt (at vector $005) is executed if an overflow in Timer/Counter0 occurs, i.e. , when the TOV0 bit is set (one) in the Timer/Counter Interrupt Flag Regi ster (TIFR).

• Bit 0 – Res: Reserved Bit

The Timer/Counter Interrupt Flag Register – TIFR

This bit is a reserved bit in the ATtiny15L and always reads as zero.

Bit 76543210 $38 –OCF1A–––TOV1TOV0–TIFR Read/Write R R/W R R R R/W R/W R Initial Value 0 0 0 0 0 0 0 0

• Bit 7 – Res: Reserved Bit

This bit is a reserved bit in the ATtiny15L and always reads as zero.

• Bit 6 – OCF1A: Output Compare Flag 1A

The OCF1A bit is set (one) when compare match occurs between Timer/Counter1 and the data value in OCR1A (Output Compare Register 1A). OCF1A is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, OCF1A is cleared by writing a logical “1” to the flag. When the I-bit in SREG, OCIE1A, and OCF1A are set (one), the Timer/Counter1 compare mat ch A interrupt is executed.

• Bits 5..3 – Res: Reserved bits

These bits are reserved bits in the ATtiny15L and always read as zero.

• Bit 2 – TOV1: Timer/Counter1 Overflow Flag

The bit TOV1 is set (one) when an overflow occurs in Timer/Counter1. TOV1 is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, TOV1 is cleared by writing a logical “1” to the flag. When the SREG I-bit, TOIE1 (Timer/Counter1 Overflow Interrupt Enable) and TOV1 are set (one), the Timer/Counter1 Overflow Interrupt is executed.

1187H–AVR–09/07

• Bit 1 – TOV0: Timer/Counter0 Overflow Flag

The bit TOV0 is set (one) when an overflow occurs in Timer/Counter0. TOV0 is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, TOV0 is cleared by writing a logical “1” to the flag. When the SREG I-bit, TOIE0 (Timer/Counter0 Overflow Interrupt Enable) and TOV0 are set (one), the Timer/Counter0 Overflow interrupt is executed.

• Bit 0 – Res: Reserved Bit

This bit is a reserved bit in the ATtiny15L and always reads as zero.

External Interrupt The External Interrupt is triggered by th e INT0 pin. O bserve that, if enabled, the inter rupt

will trigger even if the INT0 pin is configured as an output. This feature provides a way of generating a software interrupt. The External Interrupt can be triggered by a falling or rising edge, a pin change, or a low level. This is set up as indicated in the specification for the MCU Control Register (MCUCR). When the external interrupt is enabled and is configured as level-triggered, the interrupt will trigger as long as the pin is held low.

The External Interrupt is set up as described in the specification for the MCU Control Register (MCUCR).

Pin Change Interrupt The pin change interrupt is triggered by any change in logical value on any input or I/O

pin. Change on pins PB4..0 will always cause an interrupt. Change on pin PB5 will cause an interrupt if the pin is configured as input or I/O, as described in the section “Pin Descriptions” on page 4. Observe that, if enabled, the interrupt will trigger even if the changing pin is configured as an output. This feature provides a way of generating a software interrupt. Also observe that the pin change interrupt will trigger even if the pin activity triggers another interrupt, for example the external interrupt. This implies that one external event might cause several interrupts. The values on the pins are sampled before detecting edges. If pin change interrupt is enabled, pulses that last longer than one CPU clock period will generate an interrupt. Shorter pulses are not guaranteed to generate an interrupt.

The MCU Control Register – MCUCR

ATtiny15L

The MCU Control Register contains control bits for general MCU functions.

Bit 76543210 $35 – PUD SE SM1 SM0 – ISC01 ISC00 MCUCR Read/Write R R/W R/W R/W R/W R R/W R/W Initial Value00000000

• Bits 7 – Res: Reserved Bit

This bit is a reserved bit in the ATtiny15L and always reads as zero.

• Bit 6- PUD: Pull-up Disable

This PUD bit must be set (one) to disable internal pull-up registers at Port B.

• Bit 5 – SE: Sleep Enable

The SE bit must be set (one) to make the MCU enter the sleep mode when the SLEEP instruction is executed. To avoid the MCU entering the sleep mode unless it is the programmer’s purpose, it is recommended to set the Sleep Enable SE bit just before the execution of the SLEEP instruction.

1187H–AVR–09/07

ATtiny15L

• Bits 4, 3 – SM1, SM0: Sleep Mode Select Bits 1 and 0

These bits select between the three available sleep modes, as shown in Table 7.

Table 7. Sleep Modes

SM1 SM0 Sleep Mode

0 0 Idle mode 0 1 ADC Noise Reduction mode 1 0 Power-down mode 11Reserved

For details, refer to “Sleep Modes” below.

• Bit 2 – Res: Reserved Bit

This bit is a reserved bit in the ATtiny15L and always reads as 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 is set (one). The activity on the external INT0 pin that activates the interrupt is defined in Table 8:

Table 8. Interrupt 0 Sense Control

(1)

ISC01 ISC00 Description

0 0 The low level of INT0 generates an interrupt request. 0 1 Any 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.

Note: 1. When changing the ISC10/ISC00 bits, INT0 must be disabled by clearing its Interrupt

Enable bit in the GIMSK Register. Otherwise an interrupt can occur when the bits are changed.

Sleep Modes To enter any of the three sleep modes, the SE bit in MCUCR must be set (one) and a

SLEEP instruction must be executed. The SM1 and SM0 bits in the MCUCR Register select which sleep mode (Idle, ADC Noise Reduction or Power-down) will be activated by the SLEEP instruction (see Table 7). If an enabled interrupt occurs while the MCU is in a sleep mode, the MCU wakes up. The MCU is then halted for four cycles, executes the interrupt routine and resumes execution from the instruction following SLEEP. On wake-up from Power-down mode on pin change, two instruction cycles are executed before the Pin Change Interrupt Fl ag is updated. The content s of the Register File, SRAM, and I/O memory are unaltered when the device wakes up from sleep. If a reset occurs during sleep mode, the MCU wakes up and executes from the Reset Vector.

Idle Mode When the SM1/SM0 bits are “00”, the SLEEP instruction forces the MCU into the Idle

mode, stopping the CPU but allowing the ADC, Analog Comparator, Timer/Counters, Watchdog and the Interrupt system to continue operating. This enables the MCU to wake-up from external triggered interrupts as well as internal ones like the Timer Overflow Interrupt and Watchdog Reset. If the ADC is enabled, a conversion starts automatically when this mode is entered. If wake-up from the Analog Comparator interrupt is not required, the Analog Comparator can be powered down by setting the ADCbit in the Analog Comparator Control and Status Register (ACSR). This will reduce

power consumption in Idle mode.

1187H–AVR–09/07

ADC Noise Reduction Mode When the SM1/SM0 bits are “01”, the SLEEP instruction forces the MCU into the ADC

Noise Reduction mode, stopping the CPU but allowing the ADC, the external interrupt pin, pin change interrupt and the Watchdog (if enabled) to continue operating. Please note that the clock system including the PLL is also active in the ADC Noise Reduction mode. This improves the noise environment for the ADC, enabling higher resolution measurements. If the ADC is enabled, a conversio n starts auto matically when th is mode is entered. In addition to Watchdog Time-out and External Reset, only an external leveltriggered interrupt, a pin change interrupt or an ADC interrupt can wake up the MCU.

Power-down Mode When the SM1/SM0 bits are “10”, the SLEEP instruction forces the MCU into the Power-

down mode. Only an External Reset, a Watchdog Reset (if enabled), an external leveltriggered interrupt, or a pin change interrupt can wake up the MCU.

Note that if a level-triggered or pin change interrupt is used for wake-up from Powerdown mode, the changed level must be held for some time to wake up the MCU. This makes the MCU less sensitive to noise. The changed level is sampled twice by the Watchdog Oscillator clock, and if the input has the required level during this time, the MCU will wake up. The period of the Watchdog Oscillator is 2.9 25°C. The frequency of the Watchdog Oscillator is voltage-dependent as shown in the “Electrical Characteristics” section.

When waking up from the Power-down mode, a delay from the wake-up condition occurs until the wake-up becomes effective. T his allows th e clock t o rest ar t an d b ecome stable after having been stopped. The wake-up period is defined by the same CKSEL Fuses that define the Reset Time-out period.

µs (nominal) at 3.0V and

Tuneable Internal RC Oscillator

The System Clock Oscillator Calibration Register – OSCCAL

Internal PLL for Fast Peripheral Clock Generation

The internal RC Oscillator provides a fixed 1.6 MHz clock (nominal at 5V and 25°C). This internal clock is always the system clock of the ATtiny15L. This Oscillator can be calibrated by writing the calibration byte (see page 55) to the OSCCAL Register.

Bit 76543210 $31 CAL7 CAL6 CAL5 CAL4 CAL3 CAL2 CAL1 CAL0 OSCCAL Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value00000000

Writing the calibration byte to this address will trim the internal Oscillator frequency in order to remove process variations. When OSCCAL is zero (initial value), the lowest available frequency is chosen. Writing non-zero values to this register will increase the frequency of the internal oscillator. Writing $FF to the register selects the highest available frequency.

The internal PLL in ATtiny15L generates a clock frequency that is 16x multiplied from the RC Oscillator system clock. If the RC Oscillator frequency is the nominal 1.6 MHz, the fast peripheral clock is 25.6 MHz. The fast peripheral clock, or a clock prescale d from that, can be selected as the clock source for Timer/Counter1.

The PLL is locked on the tunable internal RC Oscillator and adjusting the tunable internal RC oscillator via the OSCCAL Register will adjust the fast peripheral clock at the same time. Timer1 may malfunction if the internal RC oscillator is adjusted beyond 1.75 MHz.

It is recommended not to take the OSCCAL adjustments to a higher frequency than

1.75 MHz in order to keep proper operation of all chip functions.

ATtiny15L

1187H–AVR–09/07

ATtiny15L

Timer/Counters The ATtiny15L provides two general purpose 8-bit Timer/Counters. The Timer/Counters

have separate prescaling selection from separate 10-bit prescalers. The Timer/Counter0 uses internal clock (C K) as the clock time base. The Timer/Counter1 may use either the internal clock (CK) or the fast peripheral clock (PCK) as the clock time base.

The Timer/Counter0 Prescaler

Figure 18 shows the Timer/Counter prescaler. Figure 18. Timer/Counter0 Prescaler

PSR0

CS00 CS01 CS02

CLEAR

10-BIT T/C PRESCALER

CK/8

TIMER/COUNTER0 CLOCK SOURCE

TCK0

CK/64

CK/256

CK/1024

The four prescaled selections are: CK/8, CK/64, CK/256, and CK/1024, wh ere CK is the Oscillator clock. CK, external source and stop, can also be selected as clock sources. Setting the PSR10 bit in SFIOR resets the prescaler. This allows the user to operate with a predictable prescaler.

The Timer/Counter1 Prescaler

Figure 19 shows the Timer/Counter1 prescaler. For Timer/Counter1 the clock selections are: PCK, PCK/2, PCK/4, PCK/8, CK (=PCK/16), CK/2, CK/4, CK/8,CK/16, CK/32, CK/64, CK/128, CK/256, CK/512, CK/1024, and stop. The clock options are described in Table 12 on page 31 and the Timer/Counter1 Control Register (TCCR1). Setting the PSR1 bit in the SFIOR Register resets the 10-bit prescaler . This allows t he user to ope rate with a predictable prescaler.

Figure 19. Timer/Counter1 Prescaler

(1.6 MHz)

PSR1

PCK

(25.6 MHz)

3-BIT T/C PRESCALER

CS10 CS11 CS12 CS13

CLEAR

PCK/2

PCK/4

PCK/8

TIMER/COUNTER1 CLOCK SOURCE

10-BIT T/C PRESCALER

CK/2

CK/4

CK (=PCK/16)

CK/8

CK/16

CK/32

CK/64

CK/128

CK/256

CK/512

CK/1024

1187H–AVR–09/07

The Special Function IO Register – SFIOR

Bit 76543210 $2C –––––FOC1APSR1PSR0SFIOR Read/Write R R R R R R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0

• Bit 7..3 – Res: Reserved Bits

These bits are reserved bits in the ATtiny15L and always read as zero.

• Bit 2 – FOC1A: Force Output Compare 1A

Writing a logical “1” to this bit forces a change in the Compare Match Output pin PB1 (OC1A) according to the values already set in COM1A1 and COM1A0. The Force Output Compare bit can be used to change the output pin without waiting for a compare match in timer. The automatic action programmed in COM1A1 and COM1A0 happens as if a Compare Match had occurred, but no interrupt is generated and the Timer/Counter1 will not be cleared even if CTC1 is set. The FOC1A bit will always be read as zero. The setting of the FOC1A bit has no effect in PWM mode.

• Bit 1 – PSR1: Prescaler Reset Timer/Counter1

When this bit is set (one) the Timer/Counter1 prescaler will be reset. The bit will be cleared by hardware after the operation is performed. Writing a “0” to this bit will have no effect. This bit will always be read as zero.

• Bit 0 – PSR0: Prescaler Reset Timer/Counter0

When this bit is set (one) the Timer/Counter0 prescaler will be reset. The bit will be cleared by hardware after the operation is performed. Writing a “0” to this bit will have no effect. This bit will always be read as zero.

The 8-bit Timer/Counter0 Figure 20 shows the block diagram for Timer/Counter0.

The 8-bit Timer/Counter0 can sele ct clo ck source from CK, prescaled CK or an ex te rn al pin. In addition, it can be stopped as described in the specification for the Timer/Counter0 Control Register (TCCR0). The Overflow Status Flag is found in the Timer/Counter Interrupt Flag Register (TIFR). Control signals are found in the Timer/Counter0 Control Register (TCCR0). The interrupt enable/disable settings for Timer/Counter0 are found in the Timer/Counter Interrupt Mask Register (TIMSK).

When Timer/Counter0 is externally clocked, the external signal is synchronized with the oscillator frequency of the CPU. To ensure proper sampling of the external clock, the minimum time between two external clock transitions must be at least one internal CPU clock period. The external clock signal is sampled on the rising edge of the inter nal CPU clock.

The 8-bit Timer/Counter0 features both a high-resolution and a high-accuracy usa ge with the lower prescaling opportunities. Similarly, the high-prescaling opportunities make the Timer/Counter0 useful for lower-speed functions or exact-timing functions with infrequent actions.

ATtiny15L

1187H–AVR–09/07

Figure 20. Timer/Counter0 Block Diagram

ATtiny15L

The Timer/Counter0 Control Register – TCCR0

OCIE1A

Bit 76543210 $33 – – – – – CS02 CS01 CS00 TCCR0 Read/Write R R R R R R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0

TOIE1

TOIE0

OCF1A

T/C CLK SOURCE

TOV1

TOV0TOV0

CS02

CS01

CS00

• Bits 7..3 – Res: Reserved Bits

These bits are reserved bits in the ATtiny15L and always read as zero.

• Bits 2, 1, 0 – CS02, CS01, CS00: Clock Select0, Bits 2, 1 and 0

The Clock Select0 bits 2, 1 and 0 define the prescaling source of Timer 0.

1187H–AVR–09/07

Table 9. Clock 0 Prescale Select

CS02 CS01 CS00 Description

0 0 0 Stop, the Timer/Counter0 is stopped. 001CK 010CK/8 011CK/64 100CK/256 101CK/1024 1 1 0 External Pin T0, falling edge 1 1 1 External Pin T0, rising edge

The Stop condition provides a Timer Enable/Disable function. The prescaled CK modes are scaled directly from the CK Oscillator clock. If the external pin modes are used for Timer/Counter0, transitions on PB2/(T0) will clock the counter even if the pin is configured as an output. This feature can give the user SW control of counting.

The Timer Counter 0 – TCNT0

Bit 76543210 $32 MSB LSB TCNT0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value00000000

The Timer/Counter0 is implemented as an up-counter with read and write access. If the Timer/Counter0 is written and a clock source is present, the Timer/Counter0 continues counting in the timer clock cycle following the write operation.

The 8-bit Timer/Counter1 This module features a high-resolution and a high-accuracy usage with the lower pres-

caling opportunities. Timer/Counter1 can also be used as an accurate, high speed, 8-bit Pulse Width Modulator (PWM) using clock speeds up to 25.6 MHz. In this mode, Timer/Counter1 and the Output Comp are Register s serve as a standa lone PWM. Refe r to page 34 for a detailed description of this function. Similarly, the high-prescaling opportunities make this unit useful for lower-speed functions or exact-timing functions with infrequent actions.

Figure 21 shows the block diagram for Timer/Counter1. Figure 21. Timer/Counter1 Block Diagram

T/C1 OVER-

FLOW IRQ

T/C1 A COMPARE

MATCH IRQ

T/C1 OC1A PIN/

PORT PB1

(PWM OUTPUT)

TOV1

TOIE1

TOIE0

OCIE1A

TIMER INT. MASK

TIMER/COUNTER1

(TCNT1)

8-BIT COMPARATOR

T/C1 OUTPUT T/C1 OUTPUT

COMPARE REGISTER A COMPARE REGISTER B

(OCR1A)

8-BIT DATA BUS

T/C CLEAR

OCF1A

TOV0

TIMER INT. FLAG

TOV1

OCF1A

8-BIT COMPARATOR

(OCR1B)

T/C CONTROL

CS12

PWM1

LOGIC

COM1A0

COM1A1

CS13

CTC1

T/C1 CONTROL

CS11

CS10

SFIOR

PSR1

FOC1

PSR0

CK PCK

The two Status Flags (Overflow and Compare Match) ar e found in the Timer/Counter Interrupt Flag Register (TIFR). Control signals are found in the Timer/Counter Control Register (TCCR1). The interrupt enable/disable settings are found in the Timer/Counter Interrupt Mask Register (TIMSK).

ATtiny15L

1187H–AVR–09/07

ATtiny15L

The Timer/Counter1 contains two Output Compare Registers, OCR1A and OCR1B, as the data source to be compared with the Timer/Counter1 contents. In Normal mode the Output Compare function is operational with OCR1A only, and the Output Compare function includes optional clearing of the counter on compare match, and action on the Output Compare pin (PB1) (OC1A).

In PWM mode OCR1A provides the data value against which the Timer/Counter value is compared. Upon compare match the PWM output is generated. In PWM mode The Timer/Counter counts up to the value specified in Output Compare Register OCR1B and starts again from $00. This feature allows limiting the counter “full” value to a specified value, lower than $FF. However, if OCR1n is $00, the output will remain constant and not toggle at all. If OCR1n equals $01, the pulse width will be two ticks, increasing linearly if OCR1n is larger than $01. Together with the many prescaler options, flexible PWM frequency selection is provided. Table 14 lists clock selection and OCR1B values to obtain PWM frequencies from 10 kHz to 150 kHz at 10 kHz steps.

In applications with variable PWM, halving the prescaler setting and doubling the duty cycle can be used to fine-tune the PWM. Alternatively inverted PWM can be used.

The Timer/Counter1 Control Register – TCCR1

Bit 7 6 5 4 3 2 1 0 $30 CTC1 PWM1 COM1A1 COM1A0 CS13 CS12 CS11 CS10 TCCR1 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0

• Bit 7 – CTC1: Clear Timer/Counter on Compare Match

When the CTC1 control bit is set (one), Timer/Counter1 is reset to $00 in the CPU clock cycle after a compare match with OCR1A Register value. If the control bit is cleared, Timer/Counter1 continues counting and is unaffected by a com pare match.

• Bit 6 – PWM1: Pulse Width Modulator Enable

When set (one), this bit enables PWM mode for Timer/Count er1. This mode is de scribed on page 31.

• Bits 5,4 – COM1A1, COM1A0: Compare Output Mode, Bits 1 and 0

The COM1A1 and COM1A0 control bits determine any output pin action following a compare match A in Timer/Counter1. Output pin actions affect pin PB1(OC1A). Since this is an alternative function to an I/O port, the corresponding direction control bit must be set (one) to control an output pin. The control configuration is shown in Table 10.

Table 10. Compare Mode Select

COM1A1 COM1A0 Description

(1)

1187H–AVR–09/07

0 0 Timer/Counter disconnected from output pin OC1A 0 1 Toggle the OC1A output line. 1 0 Clear the OC1A output line (to zero). 1 1 Set the OC1A output line (to one).

Note: 1. In PWM mode, these bits have a different function. Refer to Table 12 for a detailed

description.When changing the COM1A1/COM1A0 bits, the Output Compare 1A Interrupt must be disabled by clearing its Interrupt Enable bit in the TIMSK Register. Otherwise an interrupt can occur when the bits are changed.

• Bits 3, 2, 1, 0 – CS13, CS12, CS11, CS10: Clock Select Bits 3, 2, 1, and 0

The Clock Select bits 3, 2, 1, and 0 define the prescaling source of Timer/Counter1.

Table 11. Timer/Counter1 Prescale Select

CS13 CS12 CS11 CS10 Description

0000Timer/Counter1 is stopped. 0001CK*16 (=PCK) 0010CK*8 (=PCK/2) 0011CK*4 (=PCK/4) 0100CK*2 (=PCK/8) 0101CK 0110CK/2 0111CK/4 1000CK/8 1001CK/16 1010CK/32 1011CK/64 1100CK/128 1101CK/256

The Timer/Counter1 – TCNT1

1110CK/512 1111CK/1024

The Stop condition provides a Timer Enable/Disable function. The prescaled CK modes are scaled directly from the CK oscillator clock.

Bit 76543210 $2F MSB LSB TCNT1 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

This 8-bit register contains the value of Timer/Counter1 . Timer/Counter1 is implemented as an up-counter with read and write access. Due to

synchronization of the CPU and Timer/Counter1, data written into Timer/Counter1 is delayed by one CPU clock cycle.

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ATtiny15L

Timer/Counter1 Output Compare RegisterA – OCR1A

Bit 76543210 $2E MSB LSB OCR1A Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0

The Output Compare Register 1A is an 8-bit read/write register. The Timer/Counter Output Compare Register 1A contains the data to be continuously

compared with Timer/Counter1. Actions on compare matches are specified in TCCR1. A compare match occurs only if Timer/Counter1 counts to the OCR1A value. A software write that sets TCNT1 and OCR1A to the same value does not generate a compare match.

A compare match will set (one) the Compare Interrupt Flag in the CPU clock cycle following the compare event.

Timer/Counter1 in PWM Mode When the PWM mode is selected, Timer/Counter 1 and the Outp ut Comp are Regis ter A

(OCR1A) form an 8-bit, free-running and glitch-free PWM with outputs on the PB1(OC1A) pin. Timer/Counter1 acts as an up-counter, counting up from $00 up to the value specified in the second Output Compare Register OCR1B, and starting from $00 up again. When the counter value matches the contents of the Output Compare Register OCR1A, the PB1(OC1A) pin is set or cleared according to the settings of the COM1A1/COM1A0 bits in the Timer/Counter1 Control Registers TCCR1. Refer to Table 12 for details.

Table 12. Compare Mode Select in PWM Mode

COM1A1 COM1A0 Effect on Compare Pin

0 0 Not connected 0 1 Not connected

Cleared on compare match (up-counting) (non-inverted PWM). Set when TCNT1 = $00.

Set on compare match (up-counting) (inverted PWM). Cleared when TCNT1 = $00.

Note that in PWM mode, writing to the Output Compare OCR1A, the data value is first transferred to a temporary location. The value is latched into OCR1A when the Timer/Counter reaches OCR1B. This prevents the occurrence of odd-length PWM pulses (glitches) in the event of an unsynchronized OCR1A write. See Figure 22 for an example.

1187H–AVR–09/07

Figure 22. Effects of Unsynchronized OCR Latching

Compare Value Changes

Counter Value

Compare Value

PWM Output OC1A

Synchronized OC1A Latch

Compare Value Changes

Counter Value

Compare Value

PWM Output OC1A

Unsynchronized OC1A Latch

Glitch

During the time between the write and the latch operation, a read from OCR1A will read the contents of the temporary location. This means that the most recently written value always will read out of OCR1A.

When OCR1A contains $00 or the top value, as specified in OCR1B Register , the output PB1(OC1A) is held low or high according to the settings of COM1A1/COM1A0. This is shown in Table 13.

Timer/Counter1 Output Compare RegisterB – OCR1B

Bit 76543210 $2D MSB LSB OCR1B Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 1 1 1 1 1 1 1 1

The Output Compare Register1 (OCR1B) is an 8-bit read/write register. This register is used in the PWM mode only, and it limits the top value to which the Timer/Counter1 keeps counting. After reaching OCR1B in PWM mode, the counter starts from $00.

Table 13. PWM Outputs when OCR1A = $00 or OCR1B

COM1A1 COM1A0 OCR1B Output PWMn

10$00 L 1 0 OCR1B H 11$00 H 1 1 OCR1B L

In PWM mode, the Timer Overflow Flag (TOV1) is set as in no rmal Timer/Counter mode. Timer Overflow Interrupt1 operates exactly as in normal Timer/Counter mode, i.e., it is executed when TOV1 is set provided that Timer Over flow Interrupt and global interrupts are enabled. This also applies to the Timer Output Compare A Flag and interrupt.

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ATtiny15L

The frequency of the PWM will be Timer Clock Frequency divided by OCR1B value + 1.

Table 14. Timer/Counter1 Clock Prescale Select

Clock Selection OCR1B PW M Frequency

CK 159 10 kHz PCK/8 159 20 kHz PCK/4 213 30 kHz PCK/4 159 40 kHz PCK/2 255 50 kHz PCK/2 213 60 kHz PCK/2 181 70 kHz PCK/2 159 80 kHz PCK/2 141 90 kHz

PCK 255 100 kHz PCK 231 110 kHz PCK 213 120 kHz PCK 195 130 kHz PCK 181 140 kHz PCK 169 150 kHz

The exact duty-cycle of the non-inverted PWM output is:

OCR1A +1()TT1× T

-------------------------------------------------------------------- -

OCR1B +1()T

–

PCK

Where:

is the period of the selected Timer/Counter1 Clock Source.

is the period of the PCK Clock (39.1 ns).

PCK

1187H–AVR–09/07

The Watchdog Timer The Watchdog Timer is clocked from a separate On-chip Oscillator that runs at 1 MHz.

This is the typical value at V values at other V

levels. By controlling the Watchdog Timer prescaler, the Watchdog

Reset interval can be adjusted from 16 to 2,048 ms, as shown in Table 15. The WDR (Watchdog Reset) instruction resets the Watchdog Timer. Eight differe nt clock cycle periods can be selected to determine the reset per iod. I f the re set per iod ex pires without another Watchdog Reset, the ATtiny15L resets and executes from the Reset Vector. For timing details on the Watchdog Reset, refer to page 17.

To prevent unintentional disabling of th e Watchdog , a spe cial turn- off se quence must be followed when the Watchdog is disabled. Refer to th e description of th e Watchdog Timer Control Register for details.

Figure 23. Watchdog Timer

1 MHz at Vcc = 5V 350 KHz at Vcc = 3V

WATCHDOG

RESET

WDP0 WDP1 WDP2

WDE

= 5V. See “Typical Characteristics” on page 66 for typical

Oscillator

WATCHDOG

PRESCALER

The Watchdog Timer Control Register – WDTCR

MCU RESET

Bit 76543210 $21 – – – WDTOE WDE WDP2 WDP1 WDP0 WDTCR Read/Write R R R R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0

• Bits 7..5 – Res: Reserved Bits

These bits are reserved bits in the ATtiny15L and will always read as zero.

• Bit 4 – WDTOE: Watc hdog Turn-off Enable

This bit must be set (one) when the WDE bit is cleared. Otherwise, the Watchdog will not be disabled. Once set, hardware will clear this bit to zero after f our clock cycles. Refer to the description of the WDE bit for a Watchdog dis ab le pr oc ed u re .

• Bit 3 – WDE: Watchdog Enable

When the WDE is set (one), the Watchdog Timer is enabled and if the WDE is cleared (zero), the Watchdog Timer function is disabled. WDE can be cleared only when the WDTOE bit is set (one). To disable an enabled Watchdog Timer, the following procedure must be followed:

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ATtiny15L

1. In the same operation, write a logical “1” to WDTOE and WDE. A logical “1” must be written to WDE even t hough it is set to one bef or e the disab le op eration starts.

2. Within the next four clock cycles, write a logical “0” to WDE. This disables the Watchdog.

• Bits 2..0 – WDP2, WDP1, WDP0: Watchdog Timer Prescaler Bits 2, 1, and 0

The WDP2, WDP1 and WDP0 bits determine the Watchdog Timer prescaling when the Watchdog Timer is enabled. The differen t prescaling values and their corresponding time-out periods are shown in Table 15.

Table 15. Watchdog Timer Prescale Select

WDP2 WDP1 WDP0 Time-out Period

0 0 0 16K cycles 0 0 1 32K cycles 0 1 0 64K cycles 0 1 1 128K cycles 1 0 0 256K cycles 1 0 1 512K cycles 1 1 0 1,024K cycles 1 1 1 2,048K cycles

1187H–AVR–09/07

EEPROM Read/Write

The EEPROM Access Registers are accessible in the I/O space.

Access

The EEPROM Address Register – EEAR

The write access time is in the range of 4.6 - 8.2 ms, depending on the frequency of the calibrated RC Oscillator. See Table 16 for details. A self-timing function however, lets the user software detect when the next byte can be written. If the user code contains code that writes the EEPROM, some precautions must be taken. In heavily filtered power supplies, V

is likely to rise or fall slowly on Power-up/down. This causes the

device for some period of time to run at a voltage lower than specified as minimum for the clock frequency used. CPU operation under these conditions is likely to cause the Program Counter to perform unintentional jumps and eventually execute the EEPROM write code. To secure EEPROM integrity, the user is advised to use an external undervoltage reset circuit in this case.

In order to prevent unintentional EEPROM writes, a two-state write procedure must be followed. Refer to the description of the EEPROM Control Register for details of this.

When the EEPROM is read or written, the CPU is halted for two clock cycles before the next instruction is executed.

Bit 76543210 $1E – – EEAR5 EEAR4 EEAR3 EEAR2 EEAR1 EEAR0 EEAR Read/Write R R R/W R/W R/W R/W R/W R/W Initial vAlue 0 0 X X X X X X

• Bit 7, 6 – Res: Reserved Bits

These bits are reserved bits in the ATtiny15L and will always read as zero.

The EEPROM Data Register – EEDR

• Bit 5..0 – EEAR5..0: EEPROM Address

The EEPROM Address Register (EEAR) specifies the EEPROM address in the 64 bytes EEPROM space. The EEPROM data bytes are addresses linearly between 0 and 63. The initial value of EEAR is undefined. A proper value must be written befo re the EEPROM may be accessed.

Bit 76543210 $1D MSB LSB EEDR Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0

• Bit 7..0 – EEDR7..0: EEPROM Data

For the EEPROM write operation, the EEDR Register contains the data to be written to the EEPROM in the address given by the EEAR Register. For the EEPROM read operation, the EEDR contains the data read out from the EEPROM at the address given by EEAR.

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ATtiny15L

The EEPROM Control Register – EECR

Bit 76543 2 10 $1C – – – – EERIE EEMWE EEWE EERE EECR Read/Write R R R R R/W R/W R/W R/W Initial value 0 0 0 0 0 0 X 0

• Bit 7..4 – RES: Reserved Bits

These bits are reserved bits in the ATtiny15L and will always read as zero.

• Bit 3 – EERIE: EEPROM Ready Interrupt Enable

When the I-bits in SREG and EERIE are set (one), the EEPROM Ready Interrupt is enabled. When cleared (zero), the interrupt is disabled. Th e EEPROM Ready Interrupt generates a constant interrupt when EEWE is cleared (zero).

• Bit 2 – EEMWE: EEPROM Master Write Enable

The EEMWE bit determines whether setting EEWE to one causes the EEPROM to be written. When EEMWE is set (one), setting EEWE will write data to the EEPROM at the selected address. If EEMWE is zero, setting EEWE will have no effect. When EEMWE has been set (one) by software, hardware clears the bit to zero after four clock cycles. See the description of the EEWE bit for an EEPROM write procedure.

• Bit 1 – EEWE: EEPROM Write Enable

The EEPROM Write Enable Signal – EEWE – is the write strobe to the EEPROM. When address and data are correctly set up, the EEWE bit must be set to write the value in to the EEPROM. The EEMWE bit must be set when the logical “1” is written to EEWE, otherwise no EEPROM write takes place. The following procedure should be followed when writing the EEPROM (the order of steps 2 and 3 is not essential):

1. Wait until EEWE becomes zero.

2. Write new EEPROM address to EEAR (optional).

3. Write new EEPROM data to EEDR (optional).

4. Write a logical “1” to the EEMWE bit in EECR.

5. Within four clock cycles after setting EEMWE, write a logical “1” to EEWE.

1187H–AVR–09/07

Caution: An interrupt between step 4 and step 5 will make the write cycle fail, since the EEPROM Master Write Enable will time-out. If an interrupt routine accessing the EEPROM is interrupting another EEPROM access, the EEAR or EEDR Register will be modified, causing the interrupted EEPROM access to fail. It is recommended to have the Global Interrupt Flag cleared during the four last steps to avoid these problems.

When the write access time (typically 5.1 ms if the internal RC Oscillator is calibrated to

1.6 MHz) has elapsed, the EEWE bit is cleared (zero) by hardware. The user software

can poll this bit and wait for a zero before writing the next byte. When EEWE has been set, the CPU is halted for two cycles before the next instruction is executed.

• Bit 0 – EERE: EEPROM Read Enable

The EEPROM Read Enable Signal EERE is the read strobe to the EEPROM. When the correct address is set up in the EEAR Register, the EERE bit must be set. When the EERE bit is cleared (zero) by hardware, requested data is found in the EEDR Register. The EEPROM read access takes one instruction and there is no need to poll the EERE bit. When EERE has been set, the CPU is halted for four cycles before the next instruction is executed.

The user should poll the EEWE bit befor e start ing the r ead ope ration. If a write o peration is in progress when new data or address is written to the EEPROM I/O Registers, the write operation will be interrupted and the result is undefined.

The calibrated oscillator is used to time EEPROM. In Table 16 the typical programming time is listed for EEPROM access from the CPU.

Table 16. Typical EEPROM Programming Times

Preventing EEPROM Corruption

Parameter

EEPROM write (from CPU)

Number of Calibrated RC

Oscillator Cycles

8192 4.6 ms 8.2 ms

Min Programming

Time

Max Programming

Time

During periods of low VCC, the EEPROM data can be corrupted because the supply voltage is too low for the CPU and the EEPROM to operate properly. These issues are the same as for board-level systems using the EEPROM and the same design solutions should be applied.

An EEPROM data corruption can be caused by two situations when the voltage is too low. First, a regular write sequence to the EEPROM requires a minimum voltage to operate correctly. Second, the CPU itself can execute instructions incorrectly if the supply voltage for executing instructions is too low.

EEPROM data corruption can easily be avoided by following these design recommendations (one is sufficient):

1. Keep the AVR RESET active (low) during periods of insufficient power supply voltage. This can be done by enabling the internal Brown-out Detector (BOD) if the operating voltage matches the detection level. If not, an external low V

Reset Protection circuit can be applied.

2. Keep the AVR core in Power-down sleep mode during periods of low V

. This will prevent the CPU from attempting to decode and execute instructions, effectively protecting the EEPROM Registers from unintentional writes.

3. Store constants in Flash memory if the ability to change memory contents from software is not required. Flash memory cannot be updated by the CPU and will not be subject to corruption.

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ATtiny15L

The Analog Comparator

The Analog Comparator compares the input values on the positive pin PB0 (AIN0) and negative pin PB1 (AIN1). When the voltage on th e positive pin PB0 ( AIN0) is higher than the voltage on the negative pin PB1 (AI N1), the Ana log Co mpa rato r Out pu t (ACO) is set (one). The comparator’s output 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

24.

Figure 24. Analog Comparator Block Diagram

The Analog Comparator Control and Status Register – ACSR

Bit 76543210 $08 ACD ACBG ACO ACI ACIE – ACIS1 ACIS0 ACSR Read/Write R/W R/W R R/W R/W R R/W R/W Initial Value 0 0 X 0 0 0 0 0

• Bit 7 – ACD: Analog Comparator Disable

When this bit is set (one), the power to the Analog Comparator is switched off. This bit can be set at any time to turn off the Analog Comparator. This will reduce power consumption in Active and Idle mode. When changing the ACD-bit, the Analog Comparator Interrupt must be disabled by cle ar ing th e ACIE bit in ACSR. Otherwise an interrupt can occur when the bit is changed.

• Bit 6 – ACBG: Analog Comparator Bandgap Select

When this bit is set, a fixed bandgap voltage of 1.22 ± 0.05V replaces the normal input to the positive pin (AIN0) of the comparator. When this bit is cleared, the normal input pin PB0 is applied to the positive pin of the comparator.

• Bit 5 – ACO: Analog Comparator Output

ACO is directly connected to the comparator output.

• Bit 4 – ACI: Analog Comparator Interrupt Flag

This bit is set (one) when a comparator output event triggers the interrupt mode defined by ACI1 and ACI0. The Analog Comparator Interrupt routine is executed if the ACIE bit is set (one) and the I-bit in SREG is set (one). ACI is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, ACI is cleared by writing a logical “1” to the flag.

1187H–AVR–09/07

• Bit 3 – ACIE: Analog Comparator Interrupt Enable

When the ACIE bit is set (one) and the I-bit in the Status Register is set (one), the Analog Comparator Interrupt is activated. When cleared (zero), the interrupt is disabled.

• Bit 2 – Res: Reserved Bit

This bit is a reserved bit in the ATtiny15L and will always read as zero.

• Bits 1, 0 – ACIS1, ACIS0: Analog Comparator Interrupt Mode Select

These bits determine the comparator events that trigger the Analog Comparator Interrupt. The different settings are shown in Table 17.

Table 17. ACIS1/ACIS0 Settings

ACIS1 ACIS0 Interrupt Mode

0 0 Comparator Interrupt on Output Toggle 01Reserved 1 0 Comparator Interrupt on Falling Output Edge 1 1 Comparator Interrupt on Rising Output Edge

Note: 1. When changing the ACIS1/ACIS0 bits, The Analog Comparator Interrupt must be dis-

abled by clearing its Interrupt Enable bit in the ACSR Register . Otherwise an interrupt can occur when the bits are changed.

(1)

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The Analog-to-Digital Converter, Analog Multiplexer, and Gain Stages

Features • 10-bit Resolution

• ±2 LSB Absolute Accuracy

• 0.5 LSB Integral Non-linearity

• Optional Offset Cancellation

• 65 - 260 µs Conversion Time

• Up to 15 kSPS

• 4 Multiplexed Single-ended Input Channels

• 1 Differential Input Channel with Optional Gain of 20x

• 2.56V Internal Voltage Reference

• 0 - 2.56V Differential Input Voltage Range

• 0 - V

• Optional Left Adjustment for ADC Result Readout

• Free Running or Single Conversion Mode

• Interrupt on ADC Conversion Complete

• Sleep Mode Noise Canceler

Single-ended Input Voltage Range

ATtiny15L

The ATtiny15L features a 10-bit successive approximation ADC. The ADC is connected to a 4-channel Analog Multiplexer that allows one differential voltage input and four single-ended voltage inputs constructed from the pin s of Port B. The diff erenti al input (PB3, PB4) is equipped with a programmable gain stage, providing amplification step of 26 dB (20x) on the differential input voltage before the A/D conversion. The single-ended voltage inputs at PB2..PB5 refer to 0V (GND).

The ADC contains a Sample and Hold Amplifie r that ensures that the inp ut voltage to the ADC is held at a constant level during conversion. A block diagram of th e ADC is shown in Figure 25.

An internal reference voltage of nominally 2.56V is provided On-chip and this reference can optionally be externally decoupled at the AREF (PB0) pin by a capacitor for better noise performance. Alternatively, V ended channels. There is also an option to use an ex ternal voltage refere nce and turn off the internal voltage reference. These options ar e se lected using th e REFS1.. 0 bits of the ADMUX Control Register.

can be used as reference voltage for single-

1187H–AVR–09/07

Figure 25. Analog-to-Digital Converter Block Schematic

ADC CONVERSION

COMPLETE IRQ

8-BIT DATA BUS

ADIE

ADC MULTIPLEXER

SELECT (ADMUX)

REFS1

REFS0

ADLAR

MUX DECODER

MUX2

MUX1

MUX0

ADIF

ADC CTRL. & STATUS

ADIF

ADFR

ADEN

ADSC

PRESCALER

ADPS2

ADPS1

ADPS0

ADC DATA REGISTER

(ADCH/ADCL)

ADC[9:0]

VCC

AREF

ADC3

ADC2

ADC1

ADC0

INTERNAL

2.56 V

REFERENCE

NEG.

INPUT

MUX

POS.

INPUT

MUX

CHANNEL SELECTION

GAIN SELECTION

10-BIT DAC

SINGLE ENDED / DIFFERENTIAL SELECTION

GAIN AMPLIFIER

CONVERSION LOGIC

SAMPLE & HOLD COMPARATOR

Operation The ADC converts an analog input voltage to a 10-bit digital value through successive

approximation. The minimum value represents GND and the maximum value represents the selected reference voltage minus 1 LSB.

The voltage reference for the ADC may be selected by writing to the REFS1..0 bits in ADMUX. V voltage reference. Optionally, the 2.56V internal voltage refere nce may be decoupled by an external capacitor at the AREF pin to improve noise imm uni ty.

, the AREF pin, or an internal 2.56V reference may be selected as the ADC

The analog input channel and differential ga in are selected by writing to th e MUX2..0 bits in ADMUX. Any of the four ADC input pins ADC3..0 can be selected as singleended inputs to the ADC. ADC2 and ADC3 can be selected as positive and negative input, respectively, to the differential gain amp lifie r.

If differential channels are selected, the differential gain stage amplifies the voltage difference between the selected input pair by the selected gain factor, 1x or 20x, according to the setting of the MUX2..0 bits in ADMUX. This amplified value then becomes the analog input to the ADC. If single-ended channels are used, the gain amplifier is bypassed altogether.

If ADC2 is selected as both the positive and negative input to the differential gain amplifier (ADC2 - ADC2), the remaining offset in the gain stage and conversion circuitry can be measured directly as the result of the conversion. This figure can be subtracted from subsequent conversions with the same gain setting to reduce offset error to below 1 LSB.

The ADC can operate in two modes – Single Conversion and Free Running. In Single Conversion mode, each conversion will have to be initiated by the user. In Free Running

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ATtiny15L

mode, the ADC is constantly sampling and updating the ADC Data Register. The ADFR bit in ADCSR selects between the two available modes.

The ADC is enabled by setting the ADC Enable bit, ADEN in ADCSR. Voltage reference and input channel selections will not go into effect until ADEN is set. The ADC does not consume power when ADEN is cleared, so it is recommended to switch off the ADC before entering Power-saving sleep modes.

A conversion is started by writing a logical “1” to the ADC Start Conversion bit, ADSC. This bit stays high as long as the conversion is in progress and will be set to zero by hardware when the conversion is completed. If a dif ferent data chan nel is selecte d while a conversion is in progress, the ADC will finish the current conversion before performing the channel change.

The ADC generates a 10-bit result, which is presented in the ADC Data Registers, ADCH and ADCL. By default, the result is presented right-adjusted, but can optionally be presented left-adjusted by setting the ADLAR bit in ADMUX.

If the result is left-adjusted an d no m o re th an 8 -b it pr ecision is required, it is sufficient t o read ADCH. Otherwise, ADCL must be read first, then ADCH, to ensure that the content of the Data Registers belongs to the same conversion. Once ADCL is read, ADC access to data registers is blocked. This means that if ADCL has been read, and a conversion completes before ADCH is read, neither register is updated and the result from the conversion is lost. When ADCH is read, ADC access to the ADCH and ADCL Registers is re-enabled.

Prescaling and Conversion Timing

The ADC has its own interrupt, which can be triggered when a conversion completes. When ADC access to the Data Registers is prohibited between reading of ADCH and ADCL, the interrupt will trigger even if the result is lost.

Figure 26. ADC Prescaler

ADEN

ADPS0 ADPS1 ADPS2

Reset

7-BIT ADC PRESCALER

CK/2

CK/4

ADC CLOCK SOURCE

CK/8

CK/16

CK/32

CK/64

CK/128

The successive approximation circuitry requires an input clock frequency between 50 kHz and 200 kHz. Using a higher input frequency will affect the conversion accuracy, see “ADC Characteristics” on page 50. The ADC module contains a prescaler, which divides the system clock to an acceptable ADC clock frequency.

1187H–AVR–09/07

The ADPSn bits in ADCSR are used to generate a proper ADC clock input freq uency from any CK frequency above 100 kHz. The prescaler starts counting from the moment

the ADC is switched on by setting the ADEN bit in ADCSR. The prescaler keep s running for as long as the ADEN bit is set, and is continuously reset when ADEN is low.

When initiating a conversion by setting the ADSC bit in ADCSR, the conve rsion st a rts at the following rising edge of the ADC clock cycle. If differential channels are selected, the conversion will only start at every other rising edge of the ADC clock cycle after ADEN was set.

A normal conversion takes 13 ADC clock cycles. In certain situations, the ADC needs more clock cycles to perform initialization and minimize offset errors. These extended conversions take 25 ADC clock cycles and occur as the first conversion after one of the following events:

• The ADC is switched on (ADEN in ADCSR is set).

• The voltage reference source is changed (the REFS1..0 bits in ADMUX change value).

• A differential chann el is selected (MUX2 in ADMUX is “1”). Note that subsequent conversions on the same channel are not extended conversions.

The actual sample-and-hold takes place 1. 5 ADC clock cycles a fter the sta rt of a no rmal conversion and 13.5 ADC clock cycles after the start of an extended conversion. When a conversion is complete, the result is written to the ADC Data Registers, and ADIF is set. In Single Conversion mode, ADSC is cleared simultan eously. The software may then set ADSC again, and a new conversion will be initiated on the first rising ADC clock edge. In Free Running mode, a new conversion will be started imme diately after the conversion completes while ADSC remains high. Using Free Running mode and an ADC clock frequency of 200 kHz gives the lowest conversion time, 65

µs, equivalent to

15 kSPS. For a summary of conversion times, see Table 18.

Figure 27. ADC Timing Diagram, First Conversion (Single Conversion Mode)

Extended Conversion

Cycle Number

ADC Clock

ADEN

ADSC

ADIF

ADCH

ADCL

1 212

MUX and REFS Update

14 15

16 17

Sample & Hold

19 20 21 22 23

Conversion

Complete

24 25

Next Conversion

1 2

Sign and MSB of Result

LSB of Result

MUX and REFS Update

ATtiny15L

1187H–AVR–09/07

Figure 28. ADC Timing Diagram, Single Conversion

Extended Conversion

ATtiny15L

Next Conversion

Cycle Number

ADC Clock

ADEN

ADSC

ADIF

ADCH

ADCL

1 212

MUX and REFS Update

Figure 29. ADC Timing Diagram, Free Running Conversion

14 15

16 17

Sample & Hold

ycle Number

DC Clock

DSC

19 20 21 22 23

Conversion

Complete

One Conversion Next Conversion

11 12 13

24 25

Sign and MSB of Result

1 2

LSB of Result

MUX and REFS Update

DIF

DCH

DCL

Conversion

Complete

Sign and MSB of Result

LSB of Result

Sample & Ho

MUX and REFS Update

Table 18. ADC Conversion Time

Sample & Hold

Condition

(Cycles from Start of Conversion)

Extended Conversion 13.5 25.0 125 - 500 Normal Conversions 1.5 13.0 65 - 260

Conversion

Time (Cycles)

Conversion

Time (µs)

1187H–AVR–09/07

ADC Noise Canceler Function

The ADC features a noise canceler that enables conversion during ADC Noise Reduction mode (see “Sleep Modes” on page 23) to reduce noise induced from the CPU core and other I/O peripherals. If other I/O peripherals must be active during conversion, this mode works equivalently for Idle mode. To make use of this feature, the following procedure should be used:

1. Make sure th at the ADC is enabled and is not busy converting. Single Conversion mode must be selected and the ADC con ver sion complete inter rupt must be enabled.

ADEN = 1 ADSC = 0 ADFR = 0 ADIE = 1

2. Enter ADC Noise Reduction mode (or Idle mode). The ADC will start a conversion once the CPU has been halted.

3. If no other interrupts occur before the ADC conversion completes, the ADC interrupt will wake up the MCU and execute the ADC conversion complete interrupt routine.

The ADC Multiplexer Selection Register – ADMUX

Bit 76543210 $07 REFS1 REFS0 ADLAR – – MUX2 MUX1 MUX0 ADMUX Read/Write R/W R/W R/W R R R/W R/W R/W Initial Value00000000

• Bits 7..6 – REFS1..REFS0: Reference Selection Bits

These bits select the voltage reference for the ADC, as shown in Table 19. If these bits are changed during a conversion, the change will not go into effect until this conversion is complete (ADIF in ADCSR is set). Whenever these bits are changed, the next conversion will take 25 ADC clock cycles. If active channels are used, using AVCC or an external AREF higher than (AVCC - 1V) is not recommended, as this will affect ADC accuracy. The internal voltage reference options may not be used if an external reference voltage is being applied to the AREF pin.

Table 19. Voltage Reference Selection s for ADC

REFS1 REFS0 Voltage Reference Selection

00V

used as analog reference, disconnected from PB0 (AREF).

External Voltage Reference at PB0 (AREF) pin, Internal Voltage Reference turned off.

Internal Voltage Reference without external bypass capacitor, disconnected from PB0 (AREF).

Internal Voltage Reference with external bypass capacitor at PB0 (AREF) pin.

• Bit 5 – ADLAR: ADC Left Adjust Result

The ADLAR bit affects the presentation o f the ADC conversion result in the ADC Data Register. If ADLAR is cleared, the result is right-adjusted. If ADLAR is set, the result is left-adjusted. Changing the ADLAR bit will affect the ADC Data Register immediately, regardless of any ongoing conversions. For a complete description of this bit, see “The ADC Data Register – ADCL and ADCH” on page 49.

ATtiny15L

1187H–AVR–09/07

ATtiny15L

• Bits 4..3 – Res: Reserved Bits

These bits are reserved bits in the ATtiny15L and always read as zero.

• Bits 2..0 – MUX2..MUX0: Analog Channel and Gain Selection Bits 2..0

The value of these bits selects which analog input is connected to the ADC. In case of differential input (PB3 - PB4), gain selection is also made with these bits. Selecting PB3 as both inputs to the differential gain st age enables offse t measurements. Ref er to Table 20 for details. If these bits are changed during a conversion, the change will not go into effect until this conversion is complete (ADIF in ADCSR is set).

Table 20. Input Channel and Gain Selections

The ADC Control and Status Register – ADCSR

Single-ended

MUX2..0

000 ADC0 (PB5) 001 ADC1 (PB2) 010 ADC2 (PB3) 011 ADC3 (PB4)

(1)

100

(1)

101

110 ADC2 (PB3) ADC3 (PB4) 1x 111 ADC2 (PB3) ADC3 (PB4) 20x

Note: 1. For offset calibration only. See “Operation” on page 42.

Bit 76543210 $06 ADEN ADSC ADFR ADIF ADIE ADPS2 ADPS1 ADPS0 ADCSR Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value00000000

Input

N/A

Positive

Differential Input

ADC2 (PB3) ADC2 (PB3) 1x ADC2 (PB3) ADC2 (PB3) 20x

Negative

Differential Input Gain

N/A

• Bit 7 – ADEN: ADC Enable

Writing a logical “1” to this bit enables the ADC. By clearing this bit to zero, the ADC is turned off. Turning the ADC off while a conversion is in progress will terminate this conversion.

1187H–AVR–09/07

• Bit 6 – ADSC: ADC Start Conversion

In Single Conversion mode, a logical “1” must be wr itten to this bit to start each conver sion. In Free Running mode, a logical “1” must be written to this bit to start the first conversion.

When the conversion completes, ADSC returns to zero in Single Conversion mode and stays high in Free Running mode.

Writing a “0” to this bit has no effect.

• Bit 5 – ADFR: ADC Free Running Select

When this bit is set (one), the ADC operates in Free Running mode. In this mode, the ADC samples and updates the Data Registers continuously. Clearing this bit (zero) will terminate Free Running mode. If active channels a re used (MUX2 in ADMUX set), the

channel must be selected before entering Free Running mode. Selecting an active channel after entering Free Running mode may result in undefined operation from the ADC.

• Bit 4 – ADIF: ADC Interrupt Flag

This bit is set (one) when an ADC conversion completes and the Data Registers are updated. The ADC Conversion Complete Interrupt is executed if the ADIE bit and the Ibit in SREG are set (one). ADIF is clea red b y hardwar e wh en executing th e co rrespon ding interrupt handling vector. Alternatively, ADIF is cleared by writing a logical “1” to the flag. Beware that if doing a read-modify-write on ADCSR, a pending interrup t can be disabled. This also applies if the SBI and CBI instructions are used.

• Bit 3 – ADIE: ADC Interrupt Enable

When this bit is set (one) and the I-bit in SREG is s et (one), th e ADC Conver sion Complete Interrupt is activated.

• Bits 2..0 – ADPS2..ADPS0: ADC Prescaler Select Bits

These bits determine the division factor between the CK frequency and the input clock to the ADC. See Table 21.

Table 21. ADC Prescaler Selections

ADPS2 ADPS1 ADPS0 Division Factor

000 2 001 2 010 4 011 8 100 16 101 32 110 64 1 1 1 128

ATtiny15L

1187H–AVR–09/07

The ADC Data Register – ADCL and ADCH

ATtiny15L

ADLAR = 0

ADLAR = 1

Bit 1514131211109 8 $05 – – – – – – ADC9 ADC8 ADCH $04 ADC7 ADC6 ADC5 ADC4 ADC3 ADC2 ADC1 ADC0 ADCL

76543210

Read/WriteRRRRRRRR

RRRRRRRR

Initial Value00000000

00000000

Bit 1514131211109 8 $05 ADC9 ADC8 ADC7 ADC6 ADC5 ADC4 ADC3 ADC2 ADCH $04 ADC1 ADC0 – –––––ADCL

76543210

Read/WriteRRRRRRRR

RRRRRRRR

Initial Value00000000

00000000

When an ADC conversion is complete, the result is found in these two registers. When ADCL is read, the ADC Data Register is not updated until ADCH is read. If the result is left adjusted and no more than 8-bit precision is required, it is sufficient to read ADCH. Otherwise, ADCL must be read first, then ADCH. The ADLAR bit in ADMUX affects the way the result is read from the registers. If ADLAR is set, the result is left-adjusted. If ADLAR is cleared (default), the result is right-adjusted.

• ADC9..0: ADC Conversion Result

These bits represent the result from the conversion. For the differential channel, this is the value after gain adjustment, as indicated in Table 20 on page 47. For single-ended conversion, or if ADLAR or SIGN is zero, $000 represents ground and $3FF represents the selected reference voltage minus one LSB.

Scanning Multiple Channels Since change of analog channel always is de layed until a conversion is finished, the

Free Running mode can be used to scan multiple channels without interrupting the converter. Typically, the ADC Conversion Complete Interrupt will be used to perform the channel shift. However, the user should take the following fact into consideration:

The interrupt triggers once the result is ready to be read. In Free Runnin g mode, t he next conversion will start immediately when the int errupt triggers. If ADMUX is changed after the interrupt trigg ers, the ne xt conversion ha s already st arted, and t he old setting is used.

1187H–AVR–09/07

ADC Noise-canceling Techniques

Digital circuitry inside and outside the ATtiny15L generates EMI, which might affect the accuracy of analog measurements. If conversion accuracy is critical, the noise level can be reduced by applying the following techniques:

1. The analog part of the ATtiny15L and all analog components in the application should have a separate analog ground plane on the PCB. This ground plane is connected to the digital ground plane via a single point on the PCB.

2. K eep analog signal pat hs as short as possible. Mak e sure analog trac ks run ov er the analog ground plane, and keep them well away from high-speed switching digital tracks.

3. Use the ADC noise canceler function to reduce induced noise from the CPU.

4. If some Port B pins are used as digital outputs, it is essential that these do not switch while a conversion is in progress.

ADC Characteristics

Symbol Parameter Condition Min Typ Max Units

Single-ended Conversion 10.0 Bits

Resolution

Absolute Accuracy

Differential Conversion Gain = 1x or 20x

Single-ended Conversion V

= 4V

REF

ADC Clock = 200 kHz Single-ended Conversion

= 4V

REF

ADC Clock = 1 MHz

8.0 Bits

1.0 2.0 LSB

4.0 LSB

R R

REF

INT

REF

AIN

Single-ended Conversion V

= 4V

REF

ADC Clock = 2 MHz Integral Non-linearity V Differential Non-linearity V Zero Error (Offset) V Conversion Time Free Running Conversion 65.0 260.0 µs Clock Frequency 50.0 200.0 kHz

Reference Voltage

Internal Voltage Reference 2.4 2.56 2.7 V Reference Input Resistance 6.0 10.0 13.0 kΩ Analog Input Resistance 100.0 MΩ

> 2V 0.5 LSB

REF

> 2V 0.5 LSB

REF

> 2V 1.0 LSB

REF

Single-ended Conversion 2.0 V

Differential Conversion 2.0 V

16.0 LSB

- 0.2 V

ATtiny15L

1187H–AVR–09/07

ATtiny15L

I/O Port B All AVR ports have true read-modify-write functionality when used as general digital I/O

ports. This means that the direction of one port pin can be changed without unintentionally changing the direction of any other pin with the SBI and CBI instructions. The same applies for changing drive value (if configured as output) or enabling/disabling of pull-up resistors (if configured as input).

Port B is a 6-bit bi-directional I/O port. Three data memory address locations are allocated for Port B, one each for the Da ta

Register – PORTB, $18, Data Direction Register – DDRB, $17, and the Port B Input Pins – PINB, $16. The Port B Input Pins address is read-only, while the Da ta Register and the Data Direction Register are read/write.

Ports PB5..0 have special functions as described in the section “Pin Descriptions” on page 4. If PB5 is not configured as External Reset, it is input with no pull- up or as an open-drain output. All I/O pins have individually selectable pull-ups, which can be overridden with pull-up disable.

The Port B output buffers on PB0 to PB4 can sink 20 mA and thus drive LED displays directly. PB5 can sink 12 mA. When pins PB0 to PB4 are used as inputs and are externally pulled low, they will source current (I

Unconnected Pins If some pins are unused, it is recommended to ensure that these pins have a defined

level. 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 re commended, since th is may cause excessive currents if the pin is accidentally configured as an output.

) if the internal pull-ups are activated.

Alternative Functions of Port B

The Port B Data Register – PORTB

The Port B Data Direction Register – DDRB

In ATtiny15L four Port B pins – PB2, PB3, PB4, and PB5 – have alternat ive fun ction s as inputs for the ADC. If some Port B pins are configured as outputs, it is essential that these do not switch when a conversion is in progress. This might corrupt the result of the conversion. During Power-down mode and ADC Noise Reduction mode, the Schmitt triggers of the digital inputs are disconnected on these pins. This allows an analog input voltage close to V

/2 to be present during Power-down without causing excess ive

power consumption. The Port B pins with alternate functions are shown in Table 1 on page 4.

When the pins PB4..0 are used for the alternate f uncti on , the DDRB and PORT B Registers have to be set according to the alternate funct ion de scr ipt ion . When PB5 is used as External Reset pin, the values in the corresponding DDRB and PORTB bit are ignored.

Bit 76543210 $18 Read/Write R R R R/W R/WS R/W R/W R/W Initial Value00000000

Bit 76543210 $17 – – DDB5 DDB4 DDB3 DDB2 DDB1 DDB0 DDRB Read/Write R R R/W R/W R/W R/W R/W R/W Initial Value00000000

– – – PORTB4 PORTB3 PORTB2 PORTB1 PORTB0 PORTB

1187H–AVR–09/07

The Port B Input Pins Ad dress – PINB

Bit 76543210 $16 – – PINB5 PINB4 PINB3 PINB2 PINB1 PINB0 PINB Read/WriteRRRRRRRR Initial Value 0 0 N/A N/A N/A N/A N/A N/A

The Port B Input Pins address (PINB) is not a register, and this address enables access to the physical value on each Port B pin. When reading PORTB, the PORTB Data L atch is read, and when reading PINB, the logical values present on the pins are read.

PORT B as General Digital I/O The lower five pins in Port B are equal when used as digital I/O pins.

PBn, general I/O pin: The DDBn bit in the DDRB Register selects the direction of this pin. If DDBn is set (one), PBn is configured as an output pin. If DDBn is cleared (zer o), PBn is configured as an input pin. If PORTBn is set (one) when the pin is configured as an input pin, the MOS pull-up resistor is activated. To switch the pull-up resistor off, the PORTBn has to be cleared (zero) or the pin has to be configured as an output pin. Pullups for all ports can be disabled also by setting PUD-bit in the MCUCR Register.

Table 22. DDBn Effects on Port B Pins

DDBn PORTBn I/O Pull-up Comment

0 0 Input No Tri-state (High-Z) 0 1 Input No PUD bit in the MCUCR Register is set.

0 1 Input Yes

1 0 Output No Push-pull Zero Output 1 1 Output No Push-pull One Output

Note: 1. n: 4, 3…0, pin number.

On ATtiny15L, PB5 is input or open-drain output. Because this pin is used for 12V programming, there is no ESD protection diode limiting the voltage on the pin to V

+ 0.5V. Thus, special care should be taken to ensure that the voltage on this pin

does not rise above V

+ 1V during normal operation. This may cause the MCU to

reset or enter Programming mode unintentionally. All Port B pins are connected to a pin change detector that can trigger the pin change

interrupt. See “Pin Change Interrupt” on page 22 for details.

Alternate Functions of Port B The alternate pin functions of Port B are:

• RESET

– PORT B, Bit 5

(1)

PBn will source current if ext. pulled low. PUD bit in the MCUCR Register is cleared.

When the RSTDISBL Fuse is unprogrammed, this pin serves as External Reset. When the RSTDISBL Fuse is programmed, this pin is a general input pin or a open-drain output pin. If DDB5 is cleared (zero), PB5 is configured as an input pin. If DDB5 is set (one), the pin is a open-drain output.

• SCK/INT0/T0 – PORT B, Bit 2

In Serial Programming mode, this pin serves as the serial clock input, SCK. In Normal mode, this pin can serve as the external interrupt0 input. See the interrupt

description for details on how to enable this interrupt. Note that activity on this pin will trigger the interrupt even if the pin is configured as an out put.

ATtiny15L

1187H–AVR–09/07

ATtiny15L

In Normal mode, this pin can serve as the external counter clock input. See the Timer/Counter0 description for further details. If external Timer/Counter clocking is selected, activity on this pin will clock the counter even if it is configured as an output.

• MISO/OC1A/AIN1 – PORT B, Bit 1

In Serial Programming mode, this pin serves as the serial data output, MISO. In Normal mode, this pin can serve as Timer/Counter1 output compare match output

(OC1A). See the Timer/Counter1 description for further details, and how to enable the output. The OC1A pin is also the output pin for PWM mode ti mer function.

This pin also serves as the negative input of the On-chip Analog Comparator.

• MOSI/AIN0/AREF – PORT B, Bit 0

In Serial Programming mode, this pin serves as the serial data input, MOSI. In Normal mode, this pin also serves as the positive input of the On-chip Analog

Comparator. In ATtiny15L, this pin can be chosen to be the reference voltage for the ADC. Refer to

the section “The Analog-to-Digital Converter, Analog Multiplexer, and Gain Stages” for details.

1187H–AVR–09/07

Memory Programming

Program and Data Memory Lock Bits

The ATtiny15L MCU provides two Lock bits that can be left unprogrammed, “1”, or can be programmed, “0”, to obtain the additional features listed in Table 23. The Lock bits can only be erased with the Chip Erase command

Table 23. Lock Bit Protection Modes

Memory Lock Bits

Protection TypeMode LB1 LB2

1 1 1 No memory lock features enabled. 2 0 1 Further programming of the Flash and EEPROM is disabled. 3 0 0 Same as mode 2, but verify is also disabled.

Fuse Bits The ATtiny15L has six Fuse bits (BODLEVEL, BODEN, SPIEN, RSTDSBL, and

CKSEL1..0). All the Fuse bits are programmable in both High-voltage and Low-voltage Serial Programming modes. Changing t he Fu se s do es n ot h ave effe ct wh ile in p ro gr amming mode.

• The BODLEVEL Fuse selects the Brown-out Detection level and changes the startup times. See “Brown-out Detection” on page 17. See Table 5 on page 15. Default value is programmed “0”.

• When the BODEN Fuse is programed “0”, the Brown-out Detector is enabled. See “Brown-out Detection” on page 17. Default value is unprogrammed “1”.

• When the SPIEN Fuse bit is progr ammed “0”, L ow-voltage Serial Program and Data Downloading is enabled. Def ault v alue is pro grammed “0”. Unprogra mming this fuse while in the Low-voltage Serial Programming mode will disable future In-System downloading attempts.

• When the RSTDISBL Fuse is programmed “0”, the External Reset fu nction of pin PB5 is disabled in the Low-voltage Serial Programming mode will disable future In-System downloading attempts.

• CKSEL1..0 Fuses: See Table 5 on page 15 for which combination of CKSEL1..0 to use. Default v alue is “00”, 64 ms + 18 CK.

(1)

. Default v a lue is unprogrammed “1”. Programming this fuse while

The status of the Fuse bits is not affected by Chip Erase.

Note: 1. If the RSTDISBL Fuse is programmed, then the programming hardware should apply

+12V to PB5 while the ATtiny15L is in Power-on Reset. If not, the part can fail to enter Programming mode caused by drive contention on PB0 and/or PB5.

Signature Bytes All Atmel microcontrollers have a three-byte signature code that identifies the device.

The three bytes reside in a separate address space, and for the ATtiny15L they are:

1. $000 : $1E (indicates manufactured by Atmel).

2. $001 : $90 (indicates 1 Kb Flash me mory).

3. $002 : $06 (indicates ATtiny15L device when $001 is $90).

ATtiny15L

1187H–AVR–09/07

ATtiny15L

Calibration Byte The ATtiny15L has a one-byte calibration value for the internal RC Oscillator. This byte

resides in the high byte of address $000 in the sign ature addr ess space. To make use of this byte, it should be read from this location and written into the normal Flash Program memory. At start-up, the user softw ar e m ust read this Flash location and write th e va lu e to the OSCCAL Register.

Programming the Flash Atmel’s ATtiny15L offers 1K byte of In-System Reprogrammable Flash Program mem-

ory and 64 bytes of in-System Reprogrammable EEPROM Data memory. The ATtiny15L is shipped with the On-chip Flash program and EEPROM data memory

arrays in the erased state (i.e., contents = $FF) and ready to be programmed. This device supports a High-voltage (12V) Serial Prog ramming mode and a Lo w-voltage

Serial Programming mode. The +12V is use d for pr ogr amm ing e nable on ly, an d no current of significance is drawn by this pin (less than 100 Programming mode provides a convenient way to download program and data into the ATtiny15L inside the user’s system.

The Program and Data memory array s in the ATtiny15L are programmed byte-by-byte in either Programming mode. For the EEPROM, an auto-erase cycle is provided within the self-timed write instruction in the Low-voltage Seria l Programming mode.

During programming, the supply voltage must be in accordance with Table 24.

µA). The Low-voltage Serial

High-voltage Serial Programming

Table 24. Supply Voltage during Programming

Part Low-voltage Serial Programming High-volta ge Serial Programming

ATtiny15L 2.7 - 5.5V 4.5 - 5.5V

This section describes how to program and verify Flash Program memory, EEPROM Data memory, Lock bits and Fuse bits in the ATtiny15L.

Figure 30. High-voltage Serial Programming

11.5 - 12.5V 4.5 - 5.5V

ATtiny15/L

SERIAL CLOCK INPUT

PB5 (RESET)

PB3

GND

VCC

PB2

PB1

PB0

SERIAL DATA OUTPUT

SERIAL INSTR. INPUT

SERIAL DATA INPUT

1187H–AVR–09/07

High-voltage Serial Programming Algorithm

To program and verify the ATtiny15L in the High-voltage Serial Programming mode, the following sequence is recommended (See instruction formats in Table 25):

1. Power-up sequence: Apply 4.5 - 5.5V between V

and GND . Set PB5 and PB0 to “0” and wait at least

30 µs. Set PB3 to “0”. Wait at least 100 ns. Apply 12V to PB5 and wait at least 100 ns before changing PB0. Wait 8 µs before giving any instructions.

2. The Flash arra y is p rogr ammed one b yte at a time b y supplying first the a ddress, then the low and high data byte. The write instruction is self-timed; wait until the PB2 (RDY/BSY

) pin goes high.

3. The EEPROM array is programmed one byte at a time by supplying first the address, then the data b yte . The write instruction is self-timed; wait until the PB2 (RDY/BSY

) pin goes high.

4. Any memory location can be verified by using the Read instruction, which returns the contents at the selected address at serial output PB2.

5. Power-off sequence: Set PB3 to “0”. Set PB5 to “0”. Turn V

power off.

When writing or reading serial data to the ATtiny15L, data is clocked on the eigth rising edge of the 16 external clock pulses needed to generate the internal clock. See Figure 31, Figure 32, and Table 26 for an explanation.

Figure 31. High-voltage Serial Programming Waveforms

SERIAL DATA INPUT

PB0

SERIAL INSTR. INPUT

PB1

SERIAL DATA OUTPUT

PB2

INTERNAL CK

SERIAL CLOCK INPUT

PB3

MSB

MSB LSB

012345678910

16x

LSB

ATtiny15L

1187H–AVR–09/07

ATtiny15L

Table 25. High-voltage Serial Programming Instruction Set for ATtiny15L

Instruction Format

Instruction

Chip Erase

Write Flash High and Low Address

Write Flash Low Byte

Write Flash High Byte

Read Flash High and Low Address

Read Flash Low Byte

Read Flash High Byte

Write EEPROM Low Address

Write EEPROM Byte

Read EEPROM Low Address

Read EEPROM Byte

Write Fuse Bits

Write Lock Bits

Read Fuse Bits

PB0 PB1 PB2

0_1000_0000_00 0_0100_1100_00

x_xxxx_xxxx_xx

0_0001_0000_00 0_0100_1100_00

x_xxxx_xxxx_xx

0_ i i i i_i i i i _00 0_0010_1100_00

x_xxxx_xxxx_xx

0_ i i i i_i i i i _00 0_0011_1100_00

x_xxxx_xxxx_xx

0_0000_0010_00 0_0100_1100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0110_1000_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0111_1000_00

x_xxxx_xxxx_xx

0_0001_0001_00 0_0100_1100_00

x_xxxx_xxxx_xx

0_ i i i i_i i i i _00 0_0010_1100_00

x_xxxx_xxxx_xx

0_0000_0011_00 0_0100_1100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0110_1000_00

x_xxxx_xxxx_xx

0_0100_0000_00 0_0100_1100_00

x_xxxx_xxxx_xx

0_0010_0000_00 0_0100_1100_00

x_xxxx_xxxx_xx

0_0000_0100_00 0_0100_1100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0110_0100_00

x_xxxx_xxxx_xx

0_0000_000a_00 0_0001_1100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0110_0100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0111_0100_00

x_xxxx_xxxx_xx

0_0000_000a_00 0_0001_1100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0110_1100_00

o_oooo_ooox_xx

0_0000_0000_00 0_0110_1100_00

o_oooo_ooox_xx 0_00bb_bbbb_00

0_0000_1100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0110_0100_00

x_xxxx_xxxx_xx

0_00bb_bbbb_00

0_0000_1100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0110_1100_00

o_oooo_ooox_xx

0_8765_1143_00 0_0010_1100_00

x_xxxx_xxxx_xx

0_0000_0210_00 0_0010_1100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0110_1000_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0110_1100_00

x_xxxx_xxxx_xx

0_bbbb_bbbb_00

0_0000_1100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0110_1100_00 0_0000_0000_00

0_0000_0000_00 0_0111_1100_00 0_0000_0000_00

0_bbbb_bbbb_00

0_0000_1100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0110_1100_00 0_0000_0000_00

0_0000_0000_00 0_0110_0100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0110_0100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0110_1100_00

8_765x_x43x_xx

(1)

0_0000_0000_00 0_0100_1100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0110_1100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0110_1100_00 0_0000_0000_00

Operation RemarksInstr.1 Instr.2 Instr.3 Instr.4

Wait after Instr.3 until PB2 goes high for the Chip Erase cycle to finish.

Repeat Instr.2 for a new 256 byte page. Repeat Instr.3 for each new address.

Wait after Instr.3 until PB2 goes high. Repeat Instr.1, Instr. 2 and Instr.3 for each new address.

Repeat Instr.2 and Instr.3 for each new address.

Repeat Instr.1 and Instr.2 for each new address.

Repeat Instr.2 for each new address.

Wait after Instr.3 until PB2 goes high

Repeat Instr.2 for each new address.

Repeat Instr.2 for each new address

Wait after Instr.4 until PB2 goes high. Write 8 - 3 = “0” to program the Fuse bit.

Wait after Instr.4 until PB2 goes high. Write 2, 1 = “0” to program the Lock bit.

Reading 8 - 3 = “0” means the Fuse bit is programmed.

1187H–AVR–09/07

Table 25. High-voltage Serial Programming Instruction Set for ATtiny15L

Instruction Format

Instruction

Read Lock Bits

PB0 PB1 PB2

Read Signature Bytes

Read Calibration Byte

PB0 PB1 PB2

Note: 1. a = address high bits

b = address low bits i = data in o = data out

x = don’t care

1 = Lock Bit1 2 = Lock Bit2

3 = CKSEL0 Fuse 4 = CKSEL1 Fuse 5 = RSTDSBL Fuse 6 = SPIEN Fuse 7 = BODEN Fuse 8 = BODLEVEL Fuse

The Lock bits can only be cleared by executing a Chip Erase.

0_0000_0100_00 0_0100_1100_00

x_xxxx_xxxx_xx

0_0000_1000_00 0_0100_1100_00

x_xxxx_xxxx_xx

0_0000_1000_00 0_0100_1100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0111_1000_00

x_xxxx_xxxx_xx

0_0000_00bb_00

0_0000_1100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0000_1100_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0111_1100_00

x_xxxx_21xx_xx

0_0000_0000_00 0_0110_1000_00

x_xxxx_xxxx_xx

0_0000_0000_00 0_0111_1000_00

x_xxxx_xxxx_xx

(1)

(Continued)

0_0000_0000_00 0_0110_1100_00

o_oooo_ooox_xx

0_0000_0000_00 0_0111_1100_00

o_oooo_ooox_xx

Operation RemarksInstr.1 Instr.2 Instr.3 Instr.4

Reading 2, 1 = “0” means the Lock bit is programmed

Repeat Instr.2 - Instr.4 for each signature byte address

ATtiny15L

1187H–AVR–09/07

ATtiny15L

High-voltage Serial Programming Characteristics

Figure 32. High-voltage Serial Programming Timing

SDI (PB0), SII (PB1)

IVSH

SCI (PB3)

1 2 7 8 9 10 15 16

SDO (PB2)

Internal CK

Table 26. High-voltage Serial Programming Characteristics, T V

= 5.0V ± 10 % (u nle ss ot he rw ise no te d )

Symbol Parameter Min Typ Max Units

SHSL

SLSH

IVSH

SHIX

SCI (PB3) Pulse Width High 25.0 ns SCI (PB3) Pulse Width Low 25.0 ns SDI (PB0), SII (PB1) Valid to SCI (PB3) High (8th

edge) SDI (PB0), SII (PB1) Hold after SCI (PB3) High (8th

edge)

VALID

SHIX

SHOV

SHSL

SLSH

= 25°C ± 10%,

50.0 ns

Low-voltage Serial Downloading

SHOV

SCI (PB3) High (9th edge) to SDO (PB2) Valid 10.0 16.0 32.0 ns

Both the program and data memory arrays can be programmed using the SPI bus while RESET MISO (output). See Figure 33. After RESET

is pulled to GND. The serial interface consists of pins SCK, MOSI (input) and

is set low, the Programming Enable instruc-

tion needs to be executed first befor e program/erase instructions can be executed. Figure 33. Serial Programming and Verify

VCC

PB2

PB1

PB0

2.7 - 5.5V

SCK

MISO

MOSI

ATtiny15/L

PB5 (RESET)

GND

For the EEPROM, an auto-erase cycle is provided within the self-timed write instruction and there is no need to first execute the Chip E rase instr u ctio n. Th e Chip Era se in str u ction turns the content of every memory location in both the program and EEPROM arrays into $FF.

1187H–AVR–09/07

The program and EEPROM memory arrays have separate address spaces: $0000 to $01FF for Program memory and $000 to $03F for EEPROM memory.

The device is clocked from the internal clock at the uncalibrated minimum frequency (0.8 - 1.6 MHz). The minimum low and high periods for the serial clock (SCK) input are defined as follows:

Low: > 2 MCU clock cycles High: > 2 MCU clock cycles

Low-voltage Serial Programming Algorithm

When writing serial data to the ATtiny15L, data is clocked on th e rising edge of SCK. When reading data from the ATtiny15L, data is clocked on the falling edge of SCK. See Figure 34, Figure 35, and Table 28 for timing de tails. To program and verify the ATtiny15L in the Serial Programming mode, the following sequence is recommended (See 4-byte instruction formats in Table 27):

1. Power-up sequence: Apply power between V

grammer cannot guarantee that SCK is held low during Power-up, RESET

and GND while RESET and SCK are set to “0”. If the pro-

must be given a positive pulse of at least two MCU cycles duration after SCK has b een set to “0”.

2. Wait for at least 20 ms and enable serial pr ogrammin g by sending the Programming Enable serial instruction to the MOSI (PB0) pin. Refer to the above section for minimum lo w and high periods for the serial clock input SCK.

3. The serial programming instructions will not work if the communication is out of synchronization. When in sync, the second byte ($53) will echo back when issuing the third byte of the Programming Enable instruction. Whether the echo is correct or not, all four bytes of the instruction must be transmitted. If the $53 did not echo back, give SCK a positive pulse and issue a new Programming Enable instruction. If the $53 is not seen within 32 attempts, there is no functional de vice connected.

4. If a Chip Erase is performed (must be done to erase the Flash), wait t after the instruction, give RESET See Table 29 on page 63 for t

a positive pulse, and start over from step 2.

WD_ERASE

value.

WD_ERASE

5. The Flash or EEPROM array is programmed one byte at a time by supplying the address and data together with the appropriate write instruction. An EEPROM memory location is first automatically erased before new data is written. Use data polling to detect when the next byte in the Flash or EEPR OM can be written. If polling is not used, wait t

WD_PROG_FL

mitting the next instruction. See Table 30 on page 63 for the t t

WD_PROG_EE

values. In an erased device, no $FFs in the data file(s) need to be

or t

WD_PROG_EE

, respectively, before trans-

WD_PROG_FL

and

programmed.

6. Any memory location can be verified by using the Read instruction, which returns the content at the selected address at the serial output MISO (PB1) pin.

7. At the end of the programming session, RESET

can be set high to commence

normal operation.

8. Power-off sequence (if needed): Set RESET Turn V

to “1”.

power off.

ATtiny15L

1187H–AVR–09/07

ATtiny15L

Data Polling When a byte is being programmed into the Flash or EEPROM, reading the address

location being programmed will give the value $FF. At the time the device is ready for a new byte, the programmed value will read correctly. This is used to determine when the next byte can be written. This will not work for the value $FF so when programming this value, the user will have to wait for at least t Flash byte, or t

WD_PROG_EE

before the next EEPROM byte. As a chip-erased device con-

WD_PROG_FL

tains $FF in all locations, programming of addresses that are meant to contain $FF can be skipped. This does not apply if the EEPROM is reprogrammed without chip-erasing the device. In that case, data polling cannot be used for the value $FF and the user will have to wait at least t t

WD_PROG_FL

and t

WD_PROG_EE

before programming the next byte. See Table 30 for

values.

Figure 34. Low-voltage Serial Programming Waveforms

SERIAL DATA INPUT

PB0(MOSI)

MSB

before programming the next

LSB

SERIAL DATA OUTPUT

SERIAL CLOCK INPUT

PB1(MISO)

PB2(SCK)

MSB

LSB

1187H–AVR–09/07

Table 27. Low-voltage Serial Programming Instruction Set

Instruction Format

(1)

Instruction

Programming Enable 1010 1100 0101 0011 xxxx xxxx xxxx xxxx Enable Serial Programming while

Chip Erase 1010 1100 100x xxxx xxxx xxxx xxxx xxxx Chip Erase Flash and EEPROM

Read Program Memory 0010 H000 xxxx xxxa bbbb bbbb oooo oooo Read H (high or low) data o from

Write Program Memory 0100 H000 xxxx xxxa bbbb bbbb iiii iiii Write H (high or low) data i to

Read EEPROM Memory

Write EEPROM Memory

Write Lock Bits 1010 1100 1111 1211 xxxx xxxx xxxx xxxx Write Lock bits. S et bit s 1,2 = “0” to

Read Lock Bits 0101 1000 xxxx xxxx xxxx xxxx xxxx x21x Read Lock bits. “0” = programmed,

Read Signature Bytes 0011 0000 xxxx xxxx 0000 00bb oooo oooo Read signature byte o at address b. Write Fuse Bits 1010 1100 101x xxxx xxxx xxxx 8765 1143 Set bits 8 - 3 = “0” to program, “1” to

Read Fuse Bits 0101 0000 xxxx xxxx xxxx xxxx 8765 xx43 Read Fuse bits. “0” = programmed,

Read Calibration Byte 0011 1000 xxxx xxxx 0000 0000 oooo oooo

Note: 1. a = address high bits

b = address low bits H = 0 – low byte, 1 – high byte o = data out i = data in

x = don’t care

1 = Lock bit 1 2 = Lock bit 2

3 = CKSEL0 Fuse 4 = CKSEL1 Fuse 5 = RSTDISBL Fuse 6 = SPIEN Fuse 7 = BODEN Fuse 8 = BODLEVEL Fuse

1010 0000 xxxx xxxx xxbb bbbb oooo oooo Read data o from EEPROM memory

1100 0000 xxxx xxxx xxbb bbbb iiii iiii Write data i to EEPROM memory at

OperationByte 1 Byte 2 Byte 3 Byte4

is low.

RESET

memory arrays.

program memory at word address a:b.

Program memory at word address a:b.

at address b.

address b.

program Lock bits.

“1” = unprogrammed.

unprogram.

“1” = unprogrammed.

ATtiny15L

1187H–AVR–09/07

ATtiny15L

Low-voltage Serial Programming Characteristics

Figure 35. Low-voltage Serial Programming Timing

OSI

OVSH

SHOX

SLSH

SCK

SHSL

ISO

Table 28. Low-voltage Serial Programming Characteristics, T V

= 2.7 - 5.5V (Unless Otherwise Noted)

Symbol Parameter Min Typ Max Units

1/t t

CLCL

SHSL

SLSH

OVSH

SHOX

SLIV

CLCL

RC Oscillator Frequency (VCC = 2.7 - 5.5V) 0.8 1.6 MHz RC Oscillator Period (VCC = 2.7 - 5.5V) 625.0 1250.0 ns SCK Pulse Width High 2.0 t SCK Pulse Width Low 2.0 t MOSI Setup to SCK High t MOSI Hold after SCK High 2.0 t SCK Low to MISO Valid 10.0 16.0 32.0 ns

CLCL

= -40°C to 85°C,

ns ns ns ns

Table 29. Minimum Wait Delay after the Chip Erase Instruction

Symbol Minimum Wait Delay

WD_ERASE

8.2 ms

Table 30. Minimum Wait Delay after Writing a Flash or EEPROM Location

Symbol Minimum Wait Delay

WD_FLASH

WD_EEPROM

4.1 ms

8.2 ms

1187H–AVR–09/07

Electrical Characteristics

Absolute Maximum Ratings

Operating Temperature.................................. -55°C to +125°C

Storage Temperature..................................... -65°C to +150°C

Voltage on Any Pin Except RESET

with Respect to Ground.............................-1.0V to V

Voltage on RESET

with Respect to Ground....-1.0V to +13.0V

Maximum Operating Voltage ............................................ 6.0V

DC Current per I/O Pin...............................................40.0 mA

+ 0.5V

*NOTICE: Stresses beyond those listed under “Absolute

Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect de vice reliability.

DC Current

and GND Pins................................100.0 mA

DC Characteristics

TA = -40°C to 85°C, VCC = 2.7V to 5.5V

Symbol Parameter Condition Min Typ Max Units

IL1

IH1

IH2

I/O

Input Low Voltage Except (XTAL) -0.5 0.3 V Input Low Voltage XTAL -0.5 0.1 V

4.3

2.3

CC CC

(2)

VCC + 0.5 V VCC + 0.5 V VCC + 0.5 V

Input High Voltage Except (XTAL, RESET) 0.6 V Input High Voltage XTAL 0.7 V Input High Voltage RESET 0.85 V Output Low Voltage

Port B Output Low Voltage

PB5 Output High Voltage

Port B Input Leakage Current

I/O Pin Input Leakage Current

I/O Pin

(1)

IOL = 20 mA, VCC = 5V IOL = 10 mA, VCC = 3V

IOL = 12 mA, VCC = 5V

= 6 mA, VCC = 3V

(4)

IOH = -3 mA, VCC = 5V IOH = -1.5 mA, VCC = 3V

VCC = 5.5V, Pin Low (absolute value)

VCC = 5.5V, Pin High (absolute value)

I/O Pin Pull-up 35.0 122 kΩ

Active, VCC = 3V 3.0 mA

(1)

0.6

0.5

0.6

0.5

8.0 µA

V V

Idle, V

Power Supply Current

Power-down WDT enabled

Power-down WDT disabled

= 3V 1.0 1.2 mA

(2)

, VCC = 3V

(2)

, VCC = 3V

9.0 15.0 µA

<1.0 2.0 µA

ATtiny15L

1187H–AVR–09/07

ATtiny15L

DC Characteristics (Continued)

TA = -40°C to 85°C, VCC = 2.7V to 5.5V

Symbol Parameter Condition Min Typ Max Units

ACIO

ACLK

ACID

Analog Comparator Input Offset Voltage

Analog Comparator Input Leakage Current

Analog Comparator Initialization Delay

Note: 1. “Max” means the highest value where the pin is guaranteed to be read as low.

2. “Min” means the lowest value where the pin is guaranteed to be read as high.

3. Although each I/O port can sink more than the test con ditions (20 mA at V conditions (non-transient), the following must be observed: 1] The sum of all I

, for all ports, should not exceed 100 mA.

If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater than the listed test conditions.

4. Although each I/O port can source more than the test conditions (3 mA at V conditions (non-transient), the following must be observed: 1] The sum of all I

, for all ports, should not exceed 100 mA.

If IOH exceeds the test condition, VOH may exceed the related specification. Pins are not guaranteed to source current greater than the listed test condition.

5. Minimum V

for Power-down is 1.5V (only with BOD disabled).

VCC = 5V

= VCC/2

VCC = 5V

= VCC/2

VCC = 2.7V VCC = 4.0V

40.0 mV

-50.0 50.0 nA

750.0

500.0

= 5V, 10 mA at VCC = 3V) under steady state

= 5V, 1.5 mA at VCC = 3V) under steady state

1187H–AVR–09/07

Typical Characteristics

The following charts show typical behavior. These dat a are char acteri zed b ut not tested. All current consumption measurements are performed with all I/O pins configured as inputs and with internal pull-ups enabled.

The current consumption is a function of several factors such as: Operating voltage, operating frequency, loading of I/O pins, switching rate of I/O pins, code executed and ambient temperature. The dominating factors are operating voltage and frequency.

The current drawn from capacitive loaded pins may be estimated (for one pin) as C

•VCC•f where CL = load capacitance, VCC = operating voltage and f = average switch-

ing frequency of I/O pin. The difference between current consumption in Power-down mode with Watchdog

Timer enabled and Power-down mode with Watchdo g Timer disa bled represen ts the di fferential current drawn by the Watchdog Time r.

Figure 36. Active Supply Current vs. V

ACTIVE SUPPLY CURRENT vs. V

4.5

3.5

2.5

(mA)

1.5

0.5

2.5 3 3.5 4 4.5 5 5.5 6

DEVICE CLOCKED BY 1.6MHz INTERNAL RC OSCILLATOR

T = 85˚C

T = 25˚C

(V)

ATtiny15L

1187H–AVR–09/07

ATtiny15L

Figure 37. Idle Supply Current vs. V

DEVICE CLOCKED BY 1.6MHz INTERNAL RC OSCILLATOR

IDLE SUPPLY CURRENT vs. V

T = 85˚C

2.5

1.5

(mA)

0.5

2.5 3 3.5 4 4.5 5 5.5 6

(V)

Figure 38. Calibrated Internal RC Oscillator Frequency vs. V

T = 25˚C

Relative Calibrated RC Oscillator Frequency vs. Operating Voltage

1.02

= 5.0V

1.00

0.98

0.96

0.94

0.92

0.90

0.88

2 2.5 3 3.5 4 4.5 5 5.5 6

Frequency Relative to Nominal Frequency at 25˚C and V

Operating Voltage (V)

Note: The nominal calibrated RC oscillator frequency is 1.6 MHz.

T = 25˚C

25˚C

T = 85˚C

T = 45˚C

T = 70˚C

1187H–AVR–09/07

Figure 39. Bandgap Voltage vs. V

BANDGAP VOLTAGE vs. V

MEASURED WITH ANALOG COMPARATOR

1.301

T = 25˚C

1.3

T = 45˚C

1.299

1.298

1.297

(V)

1.296

T = 70˚C

T = 85˚C

1.295

1.294

1.293

1.292

1.5 2 2.5 3 3.5 4 4.5 5 5.5 6

(V)

Figure 40. Analog Comparator Offset Voltage vs. Common Mode Voltage

ANALOG COMPARATOR OFFSET VOLTAGE vs.

COMMON MODE VOLTAGE

V = 5V

T = 25˚C

T = 85˚C

Offset Voltage (mV)

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Common Mode Voltage (V)

Note: 1. Analog Comparator offset voltage is measured as absolute offset.

ATtiny15L

1187H–AVR–09/07

ATtiny15L

Figure 41. Analog Comparator Offset Voltage vs. Common Mode Voltage

ANALOG COMPARATOR OFFSET VOLTAGE vs.

COMMON MODE VOLTAGE

Offset Voltage (mV)

0 0.5 1 1.5 2 2.5 3

Common Mode Voltage (V)

Figure 42. Analog Comparator Input Leakage Current

ANALOG COMPARATOR INPUT LEAKAGE CURRENT

V = 6V

T = 25˚C

V = 2.7V

T = 25˚C

T = 85˚C

ACLK

I (nA)

-10 0 0.5 1.51 2 2.5 3.53 4 4.5 5 6 6.5 75.5

V (V)

1187H–AVR–09/07

Figure 43. Watchdog Oscillator Frequency vs. V

WATCHDOG OSCILLATOR FREQUENCY vs. V

1600

1400

1200

1000

800

F (KHz)

600

400

200

1,5 2 2,5 3 3,5 4 4,5 5 5,5 6

V (V)

T = 25˚C

T = 85˚C

Note: 1. Sink and source capabilities of I/O ports are measured on one pin at a time.

Figure 44. Pull-up Resistor Current vs. Input Voltag e

120

PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE

T = 25˚C

V = 5V

100

T = 85˚C

I (μA)

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

V (V)

ATtiny15L

1187H–AVR–09/07

Figure 45. Pull-up Resistor Current vs. Input Voltag e

ATtiny15L

PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE

V = 2.7V

T = 25˚C

T = 85˚C

I (μA)

0 0.5 1 1.5 2 2.5 3

V (V)

Figure 46. I/O Pin Sink Current vs. Output Voltage

I/O PIN SINK CURRENT vs. OUTPUT VOLTAGE

V = 5V

T = 25˚C

T = 85˚C

1187H–AVR–09/07

I (mA)

0 0.5 1 1.5 2 2.5 3

V (V)

Figure 47. I/O Pin Source Current vs. Output Voltage

I/O PIN SOURCE CURRENT vs. OUTPUT VOLTAGE

T = 25˚C

V = 5V

T = 85˚C

I (mA)

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

V (V)

Figure 48. I/O Pin Sink Current vs. Output Voltage

I/O PIN SINK CURRENT vs. OUTPUT VOLTAGE

V = 2.7V

T = 25˚C

T = 85˚C

I (mA)

0 0.5 1 1.5 2

V (V)

ATtiny15L

1187H–AVR–09/07

Figure 49. I/O Pin Source Current vs. Output Voltage

ATtiny15L

I/O PIN SOURCE CURRENT vs. OUTPUT VOLTAGE

I (mA)

0 0.5 1 1.5 2 2.5 3

T = 25˚C

T = 85˚C

V = 2.7V

V (V)

Figure 50. I/O Pin Input Threshold Voltage vs. V

I/O PIN INPUT THRESHOLD VOLTAGE vs. V

2.5

T = 25˚C

1.5

Threshold Voltage (V)

0.5

2.7 4.0 5.0

1187H–AVR–09/07

Figure 51. I/O Pin Input Hysteresis vs. V

I/O PIN INPUT HYSTERESIS vs. V

0.18

0.16

0.14

0.12

0.1

0.08

Input hysteresis (V)

0.06

0.04

0.02

2.7 4.0 5.0

T = 25˚C

ATtiny15L

1187H–AVR–09/07

ATtiny15L

ATtiny15L Register Summary

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Page

$3F SREG I T H S V N Z C page 11 $3E Reserved

$3C Reserved

$3B GIMSK - INT0 PCIE - - - - - page 19 $3A GIFR $39 TIMSK $38 TIFR -OCF1A - - - TOV1 TOV0 - page 21 $37 Reserved $36 Reserved $35 MCUCR -PUDSESM1SM0- ISC01 ISC00 page 22 $34 MCUSR - - - - WDRF BORF EXTRF PORF page 18 $33 TCCR0 - - - - - CS02 CS01 CS00 page 27 $32 TCNT0 Timer/Counter0 (8-Bit) page 28 $31 OSCCAL Oscillator Calibration Re gister page 24 $30 TCCR1 CTC1 PWM1 COM1A1 COM1A0 CS13 CS12 CS11 CS10 page 29 $2F TCNT1 Timer/Counter1 (8-Bit) page 30

$2E OCR1A Timer/Counter1 Output Compare Register A (8-Bit) page 31 $2D OCR1B Timer/Counter1 Output Compare Register B (8-Bit) page 32 $2C SFIOR - - - - - FOC1A PSR1 PSR0 page 26

$2B Reserved

$2A Reserved

$29 Reserved

$28 Reserved

$27 Reserved

$26 Reserved

$25 Reserved

$24 Reserved

$23 Reserved

$22 Reserved

$21 WDTCR - - - WDTOE WDE WDP2 WDP1 WDP0 page 34

$20 Reserved

$1F Reserved

$1E EEAR - - EEAR5 EEAR4 EEAR3 EEAR2 EEAR1 EEAR0 page 36 $1D EEDR EEPROM Data Register (8-Bit) page 36 $1C EECR - - - - EERIE EEMWE EEWE EERE page 37

$1B Reserved

$1A Reserved

$19 Reserved

$18 PORTB - - - PORTB4 PORTB3 PORTB2 PORTB1 PORTB0 page 51

$17 DDRB - - DDB5 DDB4 DDB3 DDB2 DDB1 DDB0 page 51

$16 PINB

$15 Reserved

$14 Reserved

$13 Reserved

$12 Reserved

$11 Reserved

$10 Reserved

$0F Reserved

$0E Reserved $0D Reserved $0C Reserved

$0B Reserved

$0A Reserved

$09 Reserved

$08 ACSR ACD ACBG ACO ACI ACIE - ACIS1 ACIS0 page 39

$07 ADMUX REFS1 REFS0 ADLAR

$06 ADCSR ADEN ADSC ADFR ADIF ADIE ADPS2 ADPS1 ADPS0 page 47

$05 ADCH ADC Data Register High Byte page 49

$04 ADCL ADC Data Register Low Byte page 49

… Reserved

$00 Reserved

- INTF0 PCIF - - - - - page 20

-OCIE1A- - - TOIE1 TOIE0 - page 20

- - PINB5 PINB4 PINB3 PINB2 PINB1 PINB0 page 52

- - MUX2 MUX1 MUX0 page 46

1187H–AVR–09/07

ATtiny15L Instruction Set Summary

Mnemonic Operands Description Operation Flags # Clocks

ARITHMETIC AND LOGIC INSTRUCTIONS

ADD Rd, Rr Add Two Registers Rd ← Rd + Rr Z,C,N,V,H 1 ADC Rd, Rr Add with Carry Two Registers Rd ← Rd + Rr + C Z,C,N,V,H 1 SUB Rd, Rr Subtract Two Registers Rd ← Rd - Rr Z,C,N,V,H 1 SUBI Rd, K Subtract Constant from Register Rd ← Rd - K Z,C,N,V,H 1 SBC Rd, Rr Subtract with Carry Two Registers Rd ← Rd - Rr - C Z,C,N,V,H 1 SBCI Rd, K Subtract with Carry Constant from Reg. Rd ← Rd - K - C Z,C,N,V,H 1 AND Rd, Rr Logical AND Registers Rd ← Rd • Rr Z,N,V 1 ANDI Rd, K Logical AND Register and Constant Rd ← Rd • K Z,N,V 1 OR Rd, Rr Logical OR Registers Rd ← Rd v Rr Z,N,V 1 ORI Rd, K Logical OR Register and Constant Rd ← Rd v K Z,N,V 1 EOR Rd, Rr Exclusive OR Registers Rd ← Rd⊕Rr Z,N,V 1 COM Rd One’s Complement Rd ← $FF - Rd Z,C,N,V 1 NEG Rd Two’s Complement Rd ← $00 - Rd Z,C,N,V,H 1 SBR Rd, K Set Bit(s) in Register Rd ← Rd v K Z,N,V 1 CBR Rd, K Clear Bit(s) in Register Rd ← Rd • (FFh - K) Z,N,V 1 INC Rd Increment Rd ← Rd + 1 Z,N,V 1 DEC Rd Decrement Rd ← Rd - 1 Z,N,V 1 TST Rd Test for Zero or Minus Rd ← Rd • Rd Z,N,V 1 CLR Rd Clear Register Rd ← Rd⊕Rd Z,N,V 1 SER Rd Set Register Rd ← $FF None 1

BRANCH INSTRUCTIONS

RJMP k Relative Jump PC ← PC + k + 1 None 2 RCALL k Relative Subroutine Call PC ← PC + k + 1 None 3 RET Subroutine Return PC ← STACK None 4 RETI Interrupt Return PC ← STACK I 4 CPSE Rd, Rr Compare, Skip if Equal if (Rd = Rr) PC ← PC + 2 or 3 None 1/2 CP Rd, Rr Compare Rd - Rr Z,N,V,C,H 1 CPC Rd, Rr Compare with Carry Rd - Rr - C Z,N,V,C,H 1 CPI Rd, K Compare Register with Immediate Rd - K Z,N,V,C,H 1 SBRC Rr, b Skip if Bit in Register Cleared if (Rr(b) = 0) PC ← PC + 2 or 3 None 1/2 SBRS Rr, b Skip if Bit in Register is Set if (Rr(b) = 1) PC ← PC + 2 or 3 None 1/2 SBIC P, b Skip if Bit in I/O Register Cleared if (P(b) = 0) PC ← PC + 2 or 3 None 1/2 SBIS P, b Skip if Bit in I/O Register is Set if (P(b) = 1) PC ← PC + 2 or 3 None 1/2 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 B ranch 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 B ranch 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

DATA TRANSFER INSTRUCTIONS

LD Rd, Z Load Register Indirect Rd ← (Z) None 2 ST Z, Rr Store Register Indirect (Z) ← Rr None 2 MOV Rd, Rr Move between Registers Rd ← Rr None 1 LDI Rd, K Load Immediate Rd ← KNone1 IN Rd, P In Port Rd ← PNone1 OUT P, Rr Out Port P ← Rr None 1 LPM Load Program Memory R0 ← (Z) None 3

BIT AND BIT-TEST INSTRUCTIONS

SBI P, b Set Bit in I/O Register I/O(P,b) ← 1None2

ATtiny15L

1187H–AVR–09/07

ATtiny15L

ATtiny15L Instruction Set Summary (Continued)

Mnemonic Operands Description Operation Flags # Clocks

CBI P, b Clear Bit in I/O Register I/O(P,b) ← 0None2 LSL Rd Logical Shift Left Rd(n+1) ← Rd(n), Rd(0) ← 0 Z,C,N,V 1 LSR Rd Logical Shift Right Rd(n) ← Rd(n+1), Rd(7) ← 0 Z,C,N,V 1 ROL Rd Rotate Left through Carry Rd(0) ← C, Rd(n+1) ← Rd(n), C ← Rd(7) Z,C,N,V 1 ROR Rd Rotate Right through Carry Rd(7) ← C, Rd(n) ← Rd(n+1), C ← Rd(0) Z,C,N,V 1 ASR Rd Arithmetic Shift Right Rd(n) ← Rd(n+1), n = 0..6 Z,C,N,V 1 SWAP Rd Swap Nibbles Rd(3..0) ← Rd(7..4), Rd(7..4) ← Rd(3..0) None 1 BSET s Flag Set SREG(s) ← 1 SREG(s) 1 BCLR s Flag Clear SREG(s) ← 0 SREG(s) 1 BST Rr, b Bit Store from Register to T T ← Rr(b) T 1 BLD Rd, b Bit Load from T to Register Rd(b) ← TNone1 SEC Set Carry C ← 1C1 CLC Clear Carry C ← 0C1 SEN Set Negative Flag N ← 1N1 CLN Clear Negative Flag N ← 0N1 SEZ Set Zero Flag Z ← 1Z1 CLZ Clear Zero Flag Z ← 0Z1 SEI Global Interrupt Enable I ← 1I1 CLI Global Interrupt Disable I ← 0I1 SES Set Signed Test Flag S ← 1S1 CLS Clear Signed Test Flag S ← 0S1 SEV Set Two’s Complement Overflow V ← 1V1 CLV Clear Two’s Complement Overflow V ← 0V1 SET Set T in SREG T ← 1T1 CLT Clear T in SREG T ← 0T1 SEH Set Half-carry Flag in SREG H ← 1H1 CLH Clear Half-car ry Flag in SREG H ← 0H1 NOP No Operation None 1 SLEEP Sleep (see specific descr. for Sleep function) None 1 WDR Watchdog Reset (see specific descr. for WDR/timer) None 1

1187H–AVR–09/07

Ordering Information

Power Supply Speed (MHz) Ordering Code Package Operation Range

ATtiny15L-1PC ATtiny15L-1PU ATtiny15L-1SC ATtiny15L-1SU

2.7 - 5.5V 1.6 ATtiny15L-1PI

ATtiny15L-1PU ATtiny15L-1SI ATtiny15L-1SU

Note: 1. Pb-free packaging, complies to the European Directive for Restriction of Hazardous Substances (RoHS directive). Also

Halide free and fully Green.

(1)

8P3 8P3 8S2 8S2

Commercial

(0°C to 70°C)

Industrial

(-40°C to 85°C)

ATtiny15L

1187H–AVR–09/07

Package Type

8P3 8-lead, 0.300" Wide, Plastic Dual Inline Package (PDIP) 8S2 8-lead, 0.200" Wide, Plastic Gull Wing Small Outline (EIAJ SOIC)

ATtiny15L

1187H–AVR–09/07

Packaging Information

8P3

4 PLCS

Top View

Side View

End View

COMMON DIMENSIONS

(Unit of Measure = inches)

A2 A

SYMBOL

A 0.210 2

A2 0.115 0.130 0.195

b 0.014 0.018 0.022 5

b2 0.045 0.060 0.070 6

b3 0.030 0.039 0.045 6

c 0.008 0.010 0.014

D 0.355 0.365 0.400 3

D1 0.005 3

E 0.300 0.310 0.325 4

E1 0.240 0.250 0.280 3

e 0.100 BSC

eA 0.300 BSC 4

L 0.115 0.130 0.150 2

MIN

NOM

MAX

NOTE

Notes: 1. This drawing is for general information only; refer to JEDEC Drawing MS-001, Variation BA for additional information.

2. Dimensions A and L are measured with the package seated in JEDEC seating plane Gauge GS-3.

3. D, D1 and E1 dimensions do not include mold Flash or protrusions. Mold Flash or protrusions shall not exceed 0.010 inch.

4. E and eA measured with the leads constrained to be perpendicular to datum.

5. Pointed or rounded lead tips are preferred to ease insertion.

6. b2 and b3 maximum dimensions do not include Dambar protrusions. Dambar protrusions shall not exceed 0.010 (0.25 mm).

TITLE

2325 Orchard Parkway

San Jose, CA 95131

8P3, 8-lead, 0.300" Wide Body, Plastic Dual In-line Package (PDIP)

ATtiny15L

DRAWING NO.

8P3

1187H–AVR–09/07

01/09/02

REV.

8S2

TOP VIEW

END VIEW

SIDE VIEW

ATtiny15L

TOP VIEW

SIDE VIEW

Notes: 1. This drawing is for general information only; refer to EIAJ Drawing EDR-7320 for additional information.

2. Mismatch of the upper and lower dies and resin burrs are not included.

3. It is recommended that upper and lower cavities be equal. If they are different, the larger dimension shall be regarded.

4. Determines the true geometric position.

5. Values b,C apply to plated terminal. The standard thickness of the plating layer shall measure between 0.007 to .021 mm.

END VIEW

SYMBOL

A 1.70 2.16

A1 0.05 0.25

b 0.35 0.48 5

C 0.15 0.35 5

D 5.13 5.35

E1 5.18 5.40 2, 3

E 7.70 8.26

L 0.51 0.85

θ 0° 8°

e 1.27 BSC 4

COMMON DIMENSIONS

(Unit of Measure = mm)

MIN

NOM

MAX

NOTE

4/7/06

1187H–AVR–09/07

2325 Orchard Parkway San Jose, CA 95131

TITLE

8S2, 8-lead, 0.209" Body, Plastic Small

Outline Package (EIAJ)

DRAWING NO.

8S2D

REV.

Datasheet revision history

Rev H - 09/07 1. Updated “Ordering Information” on page 78. Rev G - 06/07 1. “Not recommended for new design” Rev F - 06/05 1. Updated V

2. Added “Unconnected Pins” on page 51.

3. Updated “Packaging Information” on page 80.

in Table 4 on page 14

BOT

ATtiny15L

1187H–AVR–09/07

ATtiny15L

Table of Contents Features................................................................................................. 1

Pin Configuration.................................................................................. 1

Description............................................................................................ 2

Block Diagram...................................................................................................... 3

Pin Descriptions.................................................................................................... 4

Internal Oscillators .................................................................... ... .... ... ................. 4

ATtiny15L Architectural Overview ...................................................... 5

The General Purpose Register File ...................................................................... 6

The ALU – Arithmetic Logic Unit.......... ... ... ... ... .... ... ... ... ....................................... . 6

The Flash Program Memory................................................................................. 6

The Program and Data Addressing Modes .......................................................... 7

Subroutine and Interrupt Hardware Stack ............................................................ 9

The EEPROM Data Memory ..... ... ... .... ... ... ... ....................................... ... ... .... ... ... . 9

I/O Memory............................. ... ....................................... ... ............................... 10

Reset and Interrupt Handling.............................................................................. 12

Internal Voltage Reference................................................................................. 18

Interrupt Handling ...................................... ....................................... ... ............... 19

Sleep Modes....................................................................................................... 23

Tuneable Internal RC Oscillator....................... .... ... ... ... .... ... ............................... 24

Internal PLL for Fast Peripheral Clock Generation............................................. 24

Timer/Counters ................................................................................... 25

The Timer/Counter0 Prescaler ........................................................................... 25

The Timer/Counter1 Prescaler ........................................................................... 25

The Special Function IO Register – SFIOR........................................................ 26

The 8-bit Timer/Counter0.................................................................................... 26

The 8-bit Timer/Counter1.................................................................................... 28

The Watchdog Timer .......................................................................... 34

EEPROM Read/Write Access............................................................. 36

Preventing EEPROM Corruption........................................................................ 38

The Analog Comparator..................................................................... 39

The Analog-to-Digital Converter, Analog Multiplexer, and Gain Stag-

es.......................................................................................................... 41

Features.............................................................................................................. 41

Operation............................................................................................................ 42

Prescaling and Conversion Timing..................................................................... 43

ADC Noise Canceler Function............................................................................ 46

ADC Noise-canceling Techniques...................................................................... 50

ADC Characteristics ........................................................................................... 50

1187H–AVR–09/07

I/O Port B............................................................................................. 51

Memory Programming........................................................................ 54

Program and Data Memory Lock Bits................................................................. 54

Fuse Bits............................. .... ... ....................................... ... ... ............................ 54

Signature Bytes .................................................................................................. 54

Calibration Byte .................................................................................................. 55

Programming the Flash ...................................................................................... 55

High-voltage Serial Programming....................................................................... 55

High-voltage Serial Programming Algorithm....................................................... 56

High-voltage Serial Programming Characteristics.............................................. 59

Low-voltage Serial Downloading ........................................................................ 59

Low-voltage Serial Programming Characteristics............................................... 63

Electrical Characteristics................................................................... 64

Absolute Maximum Ratings................. ...................................... ... .... .................. 64

DC Characteristics.............................................................................................. 64

Typical Characteristics ...................................................................... 66

ATtiny15L Register Summary............................................................ 75

ATtiny15L Instruction Set Summary................................................. 76

Ordering Information.......................................................................... 78

Packaging Information....................................................................... 79

8P3 ..................................................................................................................... 79

8S2 ..................................................................................................................... 80

Datasheet revision history................................................................. 81

Rev H - 09/07...................................................................................................... 81

Rev G - 06/07 ..................................................................................................... 81

Rev F - 06/05................................ ... .... ... ...................................... .... .................. 81

Table of Contents .................................................................................. i

ATtiny15L

1187H–AVR–09/07

Headquarters Inte rnational

Atmel Corporation

2325 Orchard Parkway San Jose, CA 95131 USA Tel: 1(408) 441-0311 Fax: 1(408) 487-2600

Atmel Asia

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Product Contact

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Technical Support

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Sales Contact

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Disclaimer: The information in this document is provided in connection with Atmel products. No license, express or implied, by estoppel or otherwise, to any intellectual property right is granted by this document or in connection with the sale of Atmel products. EXCEPT AS SET FORTH IN ATMEL’S TERMS AND CONDI-

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representations or warranties with respect to the accuracy or completeness of the contents of this document and reserves the right to make changes to specifications and product descriptions at any time without notice. Atmel does not make any commitment to update the information contained here in. Unless specifically provided otherwise, Atmel products are not suitable for, and shall not be used in, automotive applications. Atmel’s products are not intended, authorized, or warranted for use as components in applications intended to suppor t or sustain life.

© Atmel Corporation 2005. All rights reserved. Atmel®, logo and combinations thereof, AVR® and others are the registered trademarks of Atmel Corporation or its subsidiaries. Other terms and product n ames may be trademarks of others.

1187H–AVR–09/07

Atmel AVR ATtiny15L User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Features

Pin Configuration

Description The ATtiny15L is a low-power CMOS 8-bit microcontroller based on the AVR RISC

Block Diagram Figure 1. The ATtiny15L Block Diag ram

Pin Descriptions

VCC Supply voltage pin. GND Ground pin. Port B (PB5..PB0) Port B is a 6-bit I/O port. PB4..0 are I/O pins that can provide internal pull-ups (selected

Analog Pins Up to four analog inputs can be selected as inputs to Analog-to-Digital Converter (ADC).

Internal Oscillators The internal Oscillator provides a clock rate of nominally 1.6 MHz for the system clock

ATtiny15L Architectural Overview

The General Purpose Register File

The Flash Program Memory

The Program and Data Addressing Modes

Register Indirect Figure 5. Indirect Register Addressing

Register Direct, T wo Register s Rd and Rr

I/O Direct Figure 7. I/O Direct Addressing

Relative Program Addressing, RJMP and RCALL

Constant Addressing using the LPM Instruction

Subroutine and Interrupt Hardware Stack

The EEPROM Data Memory

Memory Access and Instruction Execution Timing

I/O Memory The I/O space definition of the ATtiny15L is shown in Table 2.

Reset and Interrupt Handling

ATtiny15L Reset Sources The ATtiny15L has four sources of Reset:

Pow er-on Reset A Power-on Reset (POR) pulse is generated by an On-chip Dete ction circuit . The det ec-

External Reset An External Reset is generated by a low-level on the RESET

Brown-out Detection ATtiny15L has an On-chip Brown-out Detection (BOD) circuit for monitoring the V

Watchdog Reset When the Watchdog times out, it will generate a short reset pulse of one CK cycle dura-

Internal Voltage Reference

Voltage Reference Enable Signals and Start-up Time

Interrupt Handling The ATtiny15L has two 8-bit Interrupt Mask Control Registers: GIMSK (General Inter-

Interrupt Response Time The interrupt execution response for all the enabled AVR interrupts is four clock cycles

External Interrupt The External Interrupt is triggered by th e INT0 pin. O bserve that, if enabled, the inter rupt

Pin Change Interrupt The pin change interrupt is triggered by any change in logical value on any input or I/O

Table 7. Sleep Modes

Idle Mode When the SM1/SM0 bits are “00”, the SLEEP instruction forces the MCU into the Idle

ADC Noise Reduction Mode When the SM1/SM0 bits are “01”, the SLEEP instruction forces the MCU into the ADC

Power-down Mode When the SM1/SM0 bits are “10”, the SLEEP instruction forces the MCU into the Power-

Tuneable Internal RC Oscillator

Internal PLL for Fast Peripheral Clock Generation

Timer/Counters The ATtiny15L provides two general purpose 8-bit Timer/Counters. The Timer/Counters

The Timer/Counter0 Prescaler

The Timer/Counter1 Prescaler

The 8-bit Timer/Counter0 Figure 20 shows the block diagram for Timer/Counter0.

The 8-bit Timer/Counter1 This module features a high-resolution and a high-accuracy usage with the lower pres-

Timer/Counter1 in PWM Mode When the PWM mode is selected, Timer/Counter 1 and the Outp ut Comp are Regis ter A

The Watchdog Timer The Watchdog Timer is clocked from a separate On-chip Oscillator that runs at 1 MHz.

Preventing EEPROM Corruption

The Analog Comparator

The Analog-to-Digital Converter, Analog Multiplexer, and Gain Stages

Features • 10-bit Resolution

Operation The ADC converts an analog input voltage to a 10-bit digital value through successive

Prescaling and Conversion Timing

ADC Noise Canceler Function

ADLAR = 0

ADLAR = 1

Scanning Multiple Channels Since change of analog channel always is de layed until a conversion is finished, the

ADC Noise-canceling Techniques

ADC Characteristics

I/O Port B All AVR ports have true read-modify-write functionality when used as general digital I/O

Unconnected Pins If some pins are unused, it is recommended to ensure that these pins have a defined

Alternative Functions of Port B

PORT B as General Digital I/O The lower five pins in Port B are equal when used as digital I/O pins.

Alternate Functions of Port B The alternate pin functions of Port B are:

Memory Programming

Program and Data Memory Lock Bits

Fuse Bits The ATtiny15L has six Fuse bits (BODLEVEL, BODEN, SPIEN, RSTDSBL, and

Signature Bytes All Atmel microcontrollers have a three-byte signature code that identifies the device.

Calibration Byte The ATtiny15L has a one-byte calibration value for the internal RC Oscillator. This byte

Programming the Flash Atmel’s ATtiny15L offers 1K byte of In-System Reprogrammable Flash Program mem-

High-voltage Serial Programming

High-voltage Serial Programming Algorithm

High-voltage Serial Programming Characteristics

Low-voltage Serial Downloading

Low-voltage Serial Programming Algorithm

Data Polling When a byte is being programmed into the Flash or EEPROM, reading the address

Low-voltage Serial Programming Characteristics