Datasheet

ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller QFN 20 (4x4) 8-Bit 20 MHz I/O number 12

Table Of Contents

Features
1. Pin Configurations
- 1.1 Pin Descriptions
2. Overview
3. About
- 3.1 Resources
- 3.2 Code Examples
- 3.3 Data Retention
- 3.4 Disclaimer
4. CPU Core
- 4.1 Architectural Overview
- 4.2 ALU – Arithmetic Logic Unit
- 4.3 Status Register
  - 4.3.1 SREG – AVR Status Register
- 4.4 General Purpose Register File
  - 4.4.1 The X-register, Y-register, and Z-register
- 4.5 Stack Pointer
  - 4.5.1 SPH and SPL — Stack Pointer Register
- 4.6 Instruction Execution Timing
- 4.7 Reset and Interrupt Handling
  - 4.7.1 Interrupt Response Time
5. Memories
- 5.1 In-System Re-programmable Flash Program Memory
- 5.2 SRAM Data Memory
  - 5.2.1 Data Memory Access Times
- 5.3 EEPROM Data Memory
- 5.4 I/O Memory
  - 5.4.1 General Purpose I/O Registers
- 5.5 Register Description
6. Clock System
- 6.1 Clock Subsystems
- 6.2 Clock Sources
- 6.3 System Clock Prescaler
  - 6.3.1 Switching Time
- 6.4 Clock Output Buffer
- 6.5 Register Description
  - 6.5.1 OSCCAL – Oscillator Calibration Register
  - 6.5.2 CLKPR – Clock Prescale Register
7. Power Management and Sleep Modes
- 7.1 Sleep Modes
- 7.2 Software BOD Disable
  - 7.2.1 Limitations
- 7.3 Power Reduction Register
- 7.4 Minimizing Power Consumption
- 7.5 Register Description
  - 7.5.1 MCUCR – MCU Control Register
  - 7.5.2 PRR – Power Reduction Register
8. System Control and Reset
- 8.1 Resetting the AVR
- 8.2 Reset Sources
- 8.3 Internal Voltage Reference
  - 8.3.1 Voltage Reference Enable Signals and Start-up Time
- 8.4 Watchdog Timer
  - 8.4.1 Timed Sequences for Changing the Configuration of the Watchdog Timer
    - 8.4.1.1 Safety Level 1
    - 8.4.1.2 Safety Level 2
  - 8.4.2 Code Example
- 8.5 Register Description
  - 8.5.1 MCUSR – MCU Status Register
  - 8.5.2 WDTCSR – Watchdog Timer Control and Status Register
9. Interrupts
- 9.1 Interrupt Vectors
- 9.2 External Interrupts
  - 9.2.1 Low Level Interrupt
  - 9.2.2 Pin Change Interrupt Timing
- 9.3 Register Description
10. I/O Ports
- 10.1 Ports as General Digital I/O
- 10.2 Alternate Port Functions
  - 10.2.1 Alternate Functions of Port A
  - 10.2.2 Alternate Functions of Port B
- 10.3 Register Description
11. 8-bit Timer/Counter0 with PWM
- 11.1 Features
- 11.2 Overview
  - 11.2.1 Registers
  - 11.2.2 Definitions
- 11.3 Clock Sources
- 11.4 Counter Unit
- 11.5 Output Compare Unit
- 11.6 Compare Match Output Unit
  - 11.6.1 Compare Output Mode and Waveform Generation
- 11.7 Modes of Operation
- 11.8 Timer/Counter Timing Diagrams
- 11.9 Register Description
12. 16-bit Timer/Counter1
- 12.1 Features
- 12.2 Overview
- 12.3 Timer/Counter Clock Sources
- 12.4 Counter Unit
- 12.5 Input Capture Unit
- 12.6 Output Compare Units
- 12.7 Compare Match Output Unit
  - 12.7.1 Compare Output Mode and Waveform Generation
- 12.8 Modes of Operation
- 12.9 Timer/Counter Timing Diagrams
- 12.10 Accessing 16-bit Registers
  - 12.10.1 Reusing the Temporary High Byte Register
- 12.11 Register Description
13. Timer/Counter Prescaler
- 13.1 Prescaler Reset
- 13.2 External Clock Source
- 13.3 Register Description
  - 13.3.1 GTCCR – General Timer/Counter Control Register
14. USI – Universal Serial Interface
- 14.1 Features
- 14.2 Overview
- 14.3 Functional Descriptions
- 14.4 Alternative USI Usage
- 14.5 Register Descriptions
15. Analog Comparator
- 15.1 Analog Comparator Multiplexed Input
- 15.2 Register Description
16. Analog to Digital Converter
- 16.1 Features
- 16.2 Overview
- 16.3 Operation
- 16.4 Starting a Conversion
- 16.5 Prescaling and Conversion Timing
- 16.6 Changing Channel or Reference Selection
  - 16.6.1 ADC Input Channels
  - 16.6.2 ADC Voltage Reference
- 16.7 ADC Noise Canceler
- 16.8 Analog Input Circuitry
- 16.9 Noise Canceling Techniques
- 16.10 ADC Accuracy Definitions
- 16.11 ADC Conversion Result
- 16.12 Temperature Measurement
- 16.13 Register Description
17. debugWIRE On-chip Debug System
- 17.1 Features
- 17.2 Overview
- 17.3 Physical Interface
- 17.4 Software Break Points
- 17.5 Limitations of debugWIRE
- 17.6 Register Description
  - 17.6.1 DWDR – debugWire Data Register
18. Self-Programming the Flash
- 18.1 Performing Page Erase by SPM
- 18.2 Filling the Temporary Buffer (Page Loading)
- 18.3 Performing a Page Write
- 18.4 Addressing the Flash During Self-Programming
- 18.5 EEPROM Write Prevents Writing to SPMCSR
- 18.6 Reading Lock, Fuse and Signature Data from Software
- 18.7 Preventing Flash Corruption
- 18.8 Programming Time for Flash when Using SPM
- 18.9 Register Description
  - 18.9.1 SPMCSR – Store Program Memory Control and Status Register
19. Memory Programming
- 19.1 Program And Data Memory Lock Bits
- 19.2 Fuse Bytes
  - 19.2.1 Latching of Fuses
- 19.3 Device Signature Imprint Table
  - 19.3.1 Signature Bytes
  - 19.3.2 Calibration Byte
- 19.4 Page Size
- 19.5 Serial Programming
  - 19.5.1 Serial Programming Algorithm
  - 19.5.2 Serial Programming Instruction set
- 19.6 High-voltage Serial Programming
- 19.7 High-Voltage Serial Programming Algorithm
20. Electrical Characteristics
- 20.1 Absolute Maximum Ratings*
- 20.2 DC Characteristics
- 20.3 Speed
- 20.4 Clock Characteristics
  - 20.4.1 Accuracy of Calibrated Internal RC Oscillator
  - 20.4.2 External Clock Drive
- 20.5 System and Reset Characteristics
- 20.6 Analog Comparator Characteristics
- 20.7 ADC Characteristics
- 20.8 Serial Programming Characteristics
- 20.9 High-Voltage Serial Programming Characteristics
21. Typical Characteristics
- 21.1 Supply Current of I/O Modules
  - 21.1.1 Example
- 21.2 Active Supply Current
- 21.3 Idle Supply Current
- 21.4 Power-down Supply Current
- 21.5 Standby Supply Current
- 21.6 Pin Pull-up
- 21.7 Pin Driver Strength
- 21.8 Pin Threshold and Hysteresis
- 21.9 BOD Threshold and Analog Comparator Offset
- 21.10 Internal Oscillator Speed
- 21.11 Current Consumption of Peripheral Units
- 21.12 Current Consumption in Reset and Reset Pulsewidth
22. Register Summary
23. Instruction Set Summary
24. Ordering Information
- 24.1 ATtiny24
- 24.2 ATtiny44
- 24.3 ATtiny84
25. Packaging Information
- 25.1 20M1
- 25.2 14P3
- 25.3 14S1
26. Errata
- 26.1 ATtiny24
- 26.2 ATtiny44
  - 26.2.1 Rev. B – D
  - 26.2.2 Rev. A
- 26.3 ATtiny84
  - 26.3.1 Rev. A – B
27. Datasheet Revision History
- 27.1 Rev K. - 10/10
- 27.2 Rev J. - 08/10
- 27.3 Rev I. - 06/10
- 27.4 Rev H. 10/09
- 27.5 Rev G. 01/08
- 27.6 Rev F. 02/07
- 27.7 Rev E. 09/06
- 27.8 Rev D. 08/06
- 27.9 Rev C. 07/06
- 27.10 Rev B. 05/06
- 27.11 Rev A. 12/05
Table of Contents

8006K–AVR–10/10

ATtiny24/44/84

1. Write the Clock Prescaler Change Enable (CLKPCE) bit to one and all other bits in

CLKPR to zero.

2. Within four cycles, write the desired value to CLKPS while writing a zero to CLKPCE.

Interrupts must be disabled when changing prescaler setting to make sure the write procedure is

not interrupted.

The CKDIV8 Fuse determines the initial value of the CLKPS bits. If CKDIV8 is unprogrammed,

the CLKPS bits will be reset to “0000”. If CKDIV8 is programmed, CLKPS bits are reset to

“0011”, giving a division factor of eight at start up. This feature should be used if the selected

clock source has a higher frequency than the maximum frequency of the device at the present

operating conditions. Note that any value can be written to the CLKPS bits regardless of the

CKDIV8 Fuse setting. The Application software must ensure that a sufficient division factor is

chosen if the selcted clock source has a higher frequency than the maximum frequency of the

device at the present operating conditions. The device is shipped with the CKDIV8 Fuse

programmed.

Table 6-11. Clock Prescaler Select

CLKPS3 CLKPS2 CLKPS1 CLKPS0 Clock Division Factor

0000 1

0001 2

0010 4

0011 8

0100 16

0101 32

0110 64

0111 128

1000 256

1001 Reserved

1010 Reserved

1011 Reserved

1100 Reserved

1101 Reserved

1110 Reserved

1111 Reserved