- •Features
- •Pin Configurations
- •Overview
- •Block Diagram
- •Pin Descriptions
- •Port A (PA7..PA0)
- •Port B (PB7..PB0)
- •Port C (PC7..PC0)
- •Port D (PD7..PD0)
- •Port E (PE7..PE0)
- •Port F (PF7..PF0)
- •Port G (PG4..PG0)
- •RESET
- •XTAL1
- •XTAL2
- •AVCC
- •AREF
- •AVR CPU Core
- •Introduction
- •Architectural Overview
- •Status Register
- •Stack Pointer
- •Interrupt Response Time
- •SRAM Data Memory
- •Data Memory Access Times
- •EEPROM Data Memory
- •EEPROM Read/Write Access
- •I/O Memory
- •Overview
- •ATmega103 Compatibility
- •Address Latch Requirements
- •Pull-up and Bus-keeper
- •Timing
- •XMEM Register Description
- •Using all Locations of External Memory Smaller than 64 KB
- •Using all 64KB Locations of External Memory
- •Clock Systems and their Distribution
- •CPU Clock – clkCPU
- •I/O Clock – clkI/O
- •Flash Clock – clkFLASH
- •ADC Clock – clkADC
- •Clock Sources
- •Default Clock Source
- •Crystal Oscillator
- •External RC Oscillator
- •External Clock
- •Timer/Counter Oscillator
- •Idle Mode
- •Power-down Mode
- •Power-save Mode
- •Standby Mode
- •Extended Standby Mode
- •Analog to Digital Converter
- •Analog Comparator
- •Brown-out Detector
- •Internal Voltage Reference
- •Watchdog Timer
- •Port Pins
- •Resetting the AVR
- •Reset Sources
- •Power-on Reset
- •External Reset
- •Brown-out Detection
- •Watchdog Reset
- •Watchdog Timer
- •Timed Sequences for Changing the Configuration of the Watchdog Timer
- •Safety Level 0
- •Safety Level 1
- •Safety Level 2
- •Interrupts
- •I/O Ports
- •Introduction
- •Configuring the Pin
- •Reading the Pin Value
- •Unconnected pins
- •Alternate Port Functions
- •Alternate Functions of Port A
- •Alternate Functions of Port B
- •Alternate Functions of Port C
- •Alternate Functions of Port D
- •Alternate Functions of Port E
- •Alternate Functions of Port F
- •Alternate Functions of Port G
- •Register Description for I/O Ports
- •Port A Data Register – PORTA
- •Port B Data Register – PORTB
- •Port C Data Register – PORTC
- •Port D Data Register – PORTD
- •Port E Data Register – PORTE
- •Port F Data Register – PORTF
- •Port G Data Register – PORTG
- •External Interrupts
- •8-bit Timer/Counter0 with PWM and Asynchronous Operation
- •Overview
- •Registers
- •Definitions
- •Counter Unit
- •Output Compare Unit
- •Force Output Compare
- •Modes of Operation
- •Normal Mode
- •Fast PWM Mode
- •Phase Correct PWM Mode
- •Timer/Counter Prescaler
- •16-bit Timer/Counter (Timer/Counter1 and Timer/Counter3)
- •Overview
- •Registers
- •Definitions
- •Compatibility
- •Counter Unit
- •Input Capture Unit
- •Input Capture Trigger Source
- •Noise Canceler
- •Using the Input Capture Unit
- •Output Compare Units
- •Force Output Compare
- •Modes of Operation
- •Normal Mode
- •Fast PWM Mode
- •Phase Correct PWM Mode
- •Internal Clock Source
- •Prescaler Reset
- •External Clock Source
- •8-bit Timer/Counter2 with PWM
- •Overview
- •Registers
- •Definitions
- •Counter Unit
- •Output Compare Unit
- •Force Output Compare
- •Modes of Operation
- •Normal Mode
- •Fast PWM Mode
- •Phase Correct PWM Mode
- •Overview
- •Description
- •Timing Example
- •Slave Mode
- •Master Mode
- •SPI Control Register – SPCR
- •SPI Status Register – SPSR
- •SPI Data Register – SPDR
- •Data Modes
- •USART
- •Dual USART
- •Overview
- •AVR USART vs. AVR UART – Compatibility
- •Clock Generation
- •External Clock
- •Synchronous Clock Operation
- •Frame Formats
- •Parity Bit Calculation
- •USART Initialization
- •Sending Frames with 5 to 8 Data Bit
- •Sending Frames with 9 Data Bit
- •Parity Generator
- •Disabling the Transmitter
- •Receiving Frames with 5 to 8 Data Bits
- •Receiving Frames with 9 Data Bits
- •Receiver Error Flags
- •Parity Checker
- •Disabling the Receiver
- •Flushing the Receive Buffer
- •Asynchronous Data Recovery
- •Using MPCM
- •Two-wire Serial Interface
- •Features
- •TWI Terminology
- •Electrical Interconnection
- •Transferring Bits
- •START and STOP Conditions
- •Address Packet Format
- •Data Packet Format
- •Overview of the TWI Module
- •Scl and SDA Pins
- •Bit Rate Generator Unit
- •Bus Interface Unit
- •Address Match Unit
- •Control Unit
- •TWI Register Description
- •TWI Bit Rate Register – TWBR
- •TWI Control Register – TWCR
- •TWI Status Register – TWSR
- •TWI Data Register – TWDR
- •Using the TWI
- •Transmission Modes
- •Master Transmitter Mode
- •Master Receiver Mode
- •Slave Receiver Mode
- •Slave Transmitter Mode
- •Miscellaneous States
- •Analog Comparator
- •Analog to Digital Converter
- •Features
- •Operation
- •Starting a Conversion
- •Differential Gain Channels
- •Changing Channel or Reference Selection
- •ADC Input Channels
- •ADC Voltage Reference
- •ADC Noise Canceler
- •Analog Input Circuitry
- •ADC Accuracy Definitions
- •ADC Conversion Result
- •ADLAR = 0:
- •ADLAR = 1:
- •Features
- •Overview
- •Test Access Port – TAP
- •TAP Controller
- •PRIVATE0; $8
- •PRIVATE1; $9
- •PRIVATE2; $A
- •PRIVATE3; $B
- •Bibliography
- •Features
- •System Overview
- •Data Registers
- •Bypass Register
- •Device Identification Register
- •Reset Register
- •Boundary-scan Chain
- •EXTEST; $0
- •IDCODE; $1
- •SAMPLE_PRELOAD; $2
- •AVR_RESET; $C
- •BYPASS; $F
- •Boundary-scan Chain
- •Scanning the Digital Port Pins
- •Scanning the RESET Pin
- •Scanning the Clock Pins
- •Scanning the ADC
- •Boot Loader Features
- •Application Section
- •Boot Loader Section – BLS
- •Boot Loader Lock Bits
- •Performing a Page Write
- •Using the SPM Interrupt
- •Setting the Boot Loader Lock Bits by SPM
- •Reading the Fuse and Lock Bits from Software
- •Preventing Flash Corruption
- •Simple Assembly Code Example for a Boot Loader
- •Fuse Bits
- •Latching of Fuses
- •Signature Bytes
- •Calibration Byte
- •Signal Names
- •Parallel Programming
- •Enter Programming Mode
- •Chip Erase
- •Programming the Flash
- •Programming the EEPROM
- •Reading the Flash
- •Reading the EEPROM
- •Programming the Lock Bits
- •Reading the Signature Bytes
- •Reading the Calibration Byte
- •Serial Downloading
- •Data Polling Flash
- •Data Polling EEPROM
- •AVR_RESET ($C)
- •PROG_ENABLE ($4)
- •PROG_COMMANDS ($5)
- •PROG_PAGELOAD ($6)
- •PROG_PAGEREAD ($7)
- •Data Registers
- •Reset Register
- •Programming Enable Register
- •Programming Command Register
- •Virtual Flash Page Read Register
- •Programming Algorithm
- •Entering Programming Mode
- •Leaving Programming Mode
- •Performing Chip Erase
- •Programming the Flash
- •Reading the Flash
- •Programming the EEPROM
- •Reading the EEPROM
- •Programming the Fuses
- •Programming the Lock Bits
- •Reading the Signature Bytes
- •Reading the Calibration Byte
- •Electrical Characteristics
- •Absolute Maximum Ratings*
- •DC Characteristics
- •External Clock Drive Waveforms
- •External Clock Drive
- •Two-wire Serial Interface Characteristics
- •ADC Characteristics – Preliminary Data
- •External Data Memory Timing
- •Ordering Information
- •Packaging Information
- •Errata
- •ATmega128 Rev. I
- •ATmega128 Rev. H
- •ATmega128 Rev. G
- •ATmega128 Rev. F
- •Datasheet Change Log for ATmega128
- •Changes from Rev. 2467J-12/03 to Rev. 2467K-03/04
- •Changes from Rev. 2467I-09/03 to Rev. 2467J-12/03
- •Changes from Rev. 2467H-02/03 to Rev. 2467I-09/03
- •Changes from Rev. 2467G-09/02 to Rev. 2467H-02/03
- •Changes from Rev. 2467F-09/02 to Rev. 2467G-09/02
- •Changes from Rev. 2467E-04/02 to Rev. 2467F-09/02
- •Changes from Rev. 2467D-03/02 to Rev. 2467E-04/02
- •Changes from Rev. 2467C-02/02 to Rev. 2467D-03/02
- •Changes from Rev. 2467B-09/01 to Rev. 2467C-02/02
- •Table of Contents
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ATmega128 |
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be connected in such way that the ATmega128 is the fist device in the chain. |
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Update-DR will still not work for the succeeding devices in the boundary scan chain |
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as long as IDCODE is present in the JTAG Instruction Register, but the Device ID |
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registered cannot be uploaded in any case. |
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ATmega128 Rev. F |
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Stabilizing time needed when changing XDIV Register |
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Stabilizing time needed when changing OSCCAL Register |
1.Stabilizing time needed when changing XDIV Register
After increasing the source clock frequency more than 2% with settings in the XDIV register, the device may execute some of the subsequent instructions incorrectly.
Problem Fix / Workaround
The NOP instruction will always be executed correctly also right after a frequency change. Thus, the next 8 instructions after the change should be NOP instructions. To ensure this, follow this procedure:
1.Clear the I bit in the SREG Register.
2.Set the new pre-scaling factor in XDIV register. 3.Execute 8 NOP instructions
4.Set the I bit in SREG
This will ensure that all subsequent instructions will execute correctly.
Assembly Code Example:
CLI |
; clear global interrupt enable |
OUT XDIV, temp |
; set new prescale value |
NOP |
; no operation |
NOP |
; no operation |
NOP |
; no operation |
NOP |
; no operation |
NOP |
; no operation |
NOP |
; no operation |
NOP |
; no operation |
NOP |
; no operation |
SEI |
; clear global interrupt enable |
2.Stabilizing time needed when changing OSCCAL Register
After increasing the source clock frequency more than 2% with settings in the OSCCAL register, the device may execute some of the subsequent instructions incorrectly.
Problem Fix / Workaround
The behavior follows errata number 1., and the same Fix / Workaround is applicable on this errata.
A proposal for solving problems regarding the JTAG instruction IDCODE is presented below.
IDCODE masks data from TDI input
The public but optional JTAG instruction IDCODE is not implemented correctly according to IEEE1149.1; a logic one is scanned into the shift register instead of the TDI input while shifting the Device ID Register. Hence, captured data from the pre-
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2467K–AVR–04/04
ceding devices in the boundary scan chain are lost and replaced by all-ones, and data to succeeding devices are replaced by all-ones during Update-DR.
If ATmega128 is the only device in the scan chain, the problem is not visible.
Problem Fix / Workaround
Select the Device ID Register of the ATmega128 (Either by issuing the IDCODE instruction or by entering the Test-Logic-Reset state of the TAP controller) to read out the contents of its Device ID Register and possibly data from succeeding devices of the scan chain. Note that data to succeeding devices cannot be entered during this scan, but data to preceding devices can. Issue the BYPASS instruction to the ATmega128 to select its Bypass Register while reading the Device ID Registers of preceding devices of the boundary scan chain. Never read data from succeeding devices in the boundary scan chain or upload data to the succeeding devices while the Device ID Register is selected for the ATmega128. Note that the IDCODE instruction is the default instruction selected by the Test-Logic-Reset state of the TAP-controller.
Alternative Problem Fix / Workaround
If the Device IDs of all devices in the boundary scan chain must be captured simultaneously (for instance if blind interrogation is used), the boundary scan chain can be connected in such way that the ATmega128 is the fist device in the chain. Update-DR will still not work for the succeeding devices in the boundary scan chain as long as IDCODE is present in the JTAG Instruction Register, but the Device ID registered cannot be uploaded in any case.
370 ATmega128
2467K–AVR–04/04