Document Outline

• Features
• Pin Configurations
• Overview
  • Block Diagram
  • Pin Descriptions
    • VCC
    • GND
    • Port A (PA7..PA0)
    • Port B (PB7..PB0)
    • Port C (PC7..PC0)
    • Port D (PD7..PD0)
    • RESET
    • XTAL1
    • XTAL2
    • AVCC
    • AREF
• About Code Examples
• AVR CPU Core
  • Introduction
  • Architectural Overview
  • ALU – Arithmetic Logic Unit
  • Status Register
  • General Purpose Register File
    • The X-register, Y-register and Z-register
  • Stack Pointer
  • Instruction Execution Timing
  • Reset and Interrupt Handling
    • Interrupt Response Time
• AVR ATmega16 Memories
  • In-system Reprogrammable Flash Program Memory
  • SRAM Data Memory
    • Data Memory Access Times
  • EEPROM Data Memory
    • EEPROM Read/Write Access
    • The EEPROM Address Register – EEARH and EEARL
    • The EEPROM Data Register – EEDR
    • The EEPROM Control Register – EECR
    • Preventing EEPROM Corruption
  • I/O Memory
• System Clock and Clock Options
  • Clock Systems and their Distribution
    • CPU Clock – clkCPU
    • I/O Clock – clkI/O
    • Flash Clock – clkFLASH
    • Asynchronous Timer Clock – clkASY
    • ADC Clock – clkADC
  • Clock Sources
  • Crystal Oscillator
  • Low-frequency Crystal Oscillator
  • External RC Oscillator
  • Calibrated Internal RC Oscillator
    • Oscillator Calibration Register – OSCCAL
  • External Clock
  • Timer/Counter Oscillator
• Power Management and Sleep Modes
  • MCU Control Register – MCUCR
  • Idle Mode
  • ADC Noise Reduction Mode
  • Power-down Mode
  • Power-save Mode
  • Standby Mode
  • Extended Standby Mode
  • Minimizing Power Consumption
    • Analog to Digital Converter
    • Analog Comparator
    • Brown-out Detector
    • Internal Voltage Reference
    • Watchdog Timer
    • Port Pins
• System Control and Reset
  • Resetting the AVR
  • Reset Sources
  • Power-on Reset
  • External Reset
  • Brown-out Detection
  • Watchdog Reset
  • MCU Control and Status Register – MCUCSR
  • Internal Voltage Reference
    • Voltage Reference Enable Signals and Start-up Time
  • Watchdog Timer
    • Watchdog Timer Control Register – WDTCR
• Interrupts
  • Interrupt Vectors in ATmega16
    • Moving Interrupts Between Application and Boot Space
    • General Interrupt Control Register – GICR
• I/O Ports
  • Introduction
  • Ports as General Digital I/O
    • Configuring the Pin
    • Reading the Pin Value
    • Digital Input Enable and Sleep Modes
  • Alternate Port Functions
    • Special Function I/O Register – SFIOR
    • Alternate Functions of Port A
    • Alternate Functions of Port B
    • Alternate Functions of Port C
    • Alternate Functions of Port D
  • Register Description for I/O Ports
    • Port A Data Register – PORTA
    • Port A Data Direction Register – DDRA
    • Port A Input Pins Address – PINA
    • Port B Data Register – PORTB
    • Port B Data Direction Register – DDRB
    • Port B Input Pins Address – PINB
    • Port C Data Register – PORTC
    • Port C Data Direction Register – DDRC
    • Port C Input Pins Address – PINC
    • Port D Data Register – PORTD
    • Port D Data Direction Register – DDRD
    • Port D Input Pins Address – PIND
• External Interrupts
  • MCU Control Register – MCUCR
  • MCU Control and Status Register – MCUCSR
  • General Interrupt Control Register – GICR
  • General Interrupt Flag Register – GIFR
• 8-bit Timer/Counter0 with PWM
  • Overview
    • Registers
    • Definitions
  • Timer/Counter Clock Sources
  • Counter Unit
  • Output Compare Unit
    • Force Output Compare
    • Compare Match Blocking by TCNT0 Write
    • Using the Output Compare Unit
  • Compare Match Output Unit
    • Compare Output Mode and Waveform Generation
  • Modes of Operation
    • Normal Mode
    • Clear Timer on Compare Match (CTC) Mode
    • Fast PWM Mode
    • Phase Correct PWM Mode
  • Timer/Counter Timing Diagrams
  • 8-bit Timer/Counter Register Description
    • Timer/Counter Control Register – TCCR0
    • Timer/Counter Register – TCNT0
    • Output Compare Register – OCR0
    • Timer/Counter Interrupt Mask Register – TIMSK
    • Timer/Counter Interrupt Flag Register – TIFR
• Timer/Counter0 and Timer/Counter1 Prescalers
  • Internal Clock Source
  • Prescaler Reset
  • External Clock Source
  • Special Function IO Register – SFIOR
• 16-bit Timer/Counter1
  • Overview
    • Registers
    • Definitions
    • Compatibility
  • Accessing 16-bit Registers
    • Reusing the Temporary High Byte Register
  • Timer/Counter Clock Sources
  • Counter Unit
  • Input Capture Unit
    • Input Capture Trigger Source
    • Noise Canceler
    • Using the Input Capture Unit
  • Output Compare Units
    • Force Output Compare
    • Compare Match Blocking by TCNT1 Write
    • Using the Output Compare Unit
  • Compare Match Output Unit
    • Compare Output Mode and Waveform Generation
  • Modes of Operation
    • Normal Mode
    • Clear Timer on Compare Match (CTC) Mode
    • Fast PWM Mode
    • Phase Correct PWM Mode
    • Phase and Frequency Correct PWM Mode
  • Timer/Counter Timing Diagrams
  • 16-bit Timer/Counter Register Description
    • Timer/Counter 1 Control Register A – TCCR1A
    • Timer/Counter 1 Control Register B – TCCR1B
    • Timer/Counter 1 – TCNT1H and TCNT1L
    • Output Compare Register 1 A – OCR1AH and OCR1AL
    • Output Compare Register 1 B – OCR1BH and OCR1BL
    • Input Capture Register 1 – ICR1H and ICR1L
    • Timer/Counter Interrupt Mask Register – TIMSK(1)
    • Timer/Counter Interrupt Flag Register – TIFR
• 8-bit Timer/Counter2 with PWM and Asynchronous Operation
  • Overview
    • Registers
    • Definitions
  • Timer/Counter Clock Sources
  • Counter Unit
  • Output Compare Unit
    • Force Output Compare
    • Compare Match Blocking by TCNT2 Write
    • Using the Output Compare Unit
  • Compare Match Output Unit
    • Compare Output Mode and Waveform Generation
  • Modes of Operation
    • Normal Mode
    • Clear Timer on Compare Match (CTC) Mode
    • Fast PWM Mode
    • Phase Correct PWM Mode
  • Timer/Counter Timing Diagrams
  • 8-bit Timer/Counter Register Description
    • Timer/Counter Control Register – TCCR2
    • Timer/Counter Register – TCNT2
    • Output Compare Register - OCR2
  • Asynchronous Operation of the Timer/Counter
    • Asynchronous Status Register – ASSR
    • Asynchronous Operation of Timer/Counter2
    • Timer/Counter Interrupt Mask Register – TIMSK
    • Timer/Counter Interrupt Flag Register – TIFR
  • Timer/Counter Prescaler
    • Special Function IO Register – SFIOR
• Serial Peripheral Interface – SPI
  • SS Pin Functionality
    • Slave Mode
    • Master Mode
    • SPI Control Register – SPCR
    • SPI Status Register – SPSR
    • SPI Data Register – SPDR
  • Data Modes
• USART
  • Overview
    • AVR USART vs. AVR UART - Compatibility
  • Clock Generation
    • Internal Clock Generation – The Baud Rate Generator
    • Double Speed Operation (U2X)
    • External Clock
    • Synchronous Clock Operation
  • Frame Formats
    • Parity Bit Calculation
  • USART Initialization
  • Data Transmission – The USART Transmitter
    • Sending Frames with 5 to 8 Data Bit
    • Sending Frames with 9Data Bit
    • Transmitter Flags and Interrupts
    • Parity Generator
    • Disabling the Transmitter
  • Data Reception – The USART Receiver
    • Receiving Frames with 5 to 8 Data Bits
    • Receiving Frames with 9 Databits
    • Receive Compete Flag and Interrupt
    • Receiver Error Flags
    • Parity Checker
    • Disabling the Receiver
    • Flushing the Receive Buffer
  • Asynchronous Data Reception
    • Asynchronous Clock Recovery
    • Asynchronous Data Recovery
    • Asynchronous Operational Range
  • Multi-processor Communication Mode
    • Using MPCM
  • Accessing UBRRH/ UCSRC Registers
    • Write Access
    • Read Access
  • USART Register Description
    • USART I/O Data Register – UDR
    • USART Control and Status Register A – UCSRA
    • USART Control and Status Register B – UCSRB
    • USART Control and Status Register C – UCSRC
    • USART Baud Rate Registers – UBRRL and UBRRHs
  • Examples of Baud Rate Setting
• Two-wire Serial Interface
  • Features
  • Two-wire Serial Interface Bus Definition
    • TWI Terminology
    • Electrical Interconnection
  • Data Transfer and Frame Format
    • Transferring Bits
    • START and STOP Conditions
    • Address Packet Format
    • Data Packet Format
    • Combining Address and Data Packets into a Transmission
  • Multi-master Bus Systems, Arbitration and Synchronization
  • 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
    • TWI (Slave) Address Register – TWAR
  • Using the TWI
  • Transmission Modes
    • Master Transmitter Mode
    • Master Receiver Mode
    • Slave Receiver Mode
    • Slave Transmitter Mode
    • Miscellaneous States
    • Combining Several TWI Modes
  • Multi-master Systems and Arbitration
• Analog Comparator
  • Special Function IO Register – SFIOR
  • Analog Comparator Control and Status Register – ACSR
  • Analog Comparator Multiplexed Input
• Analog to Digital Converter
  • Features
  • Operation
  • Starting a Conversion
  • Prescaling and Conversion Timing
    • Differential Gain Channels
  • Changing Channel or Reference Selection
    • ADC Input Channels
    • ADC Voltage Reference
  • ADC Noise Canceler
    • Analog Input Circuitry
    • Analog Noise Canceling Techniques
    • Offset Compensation Schemes
    • ADC Accuracy Definitions
  • ADC Conversion Result
    • ADC Multiplexer Selection Register – ADMUX
    • ADC Control and Status Register A – ADCSRA
    • The ADC Data Register – ADCL and ADCH
    • Special FunctionIO Register – SFIOR
• JTAG Interface and On-chip Debug System
  • Features
  • Overview
  • Test Access Port - TAP
  • TAP Controller
  • Using the Boundary- scan Chain
  • Using the On-chip Debug System
  • On-chip Debug Specific JTAG Instructions
    • PRIVATE0; $8
    • PRIVATE1; $9
    • PRIVATE2; $A
    • PRIVATE3; $B
  • On-chip Debug Related Register in I/O Memory
    • On-chip Debug Register – OCDR
  • Using the JTAG Programming Capabilities
  • Bibliography
• IEEE 1149.1 (JTAG) Boundary-scan
  • Features
  • System Overview
  • Data Registers
    • Bypass Register
    • Device Identification Register
    • Reset Register
    • Boundary-scan Chain
  • Boundary-scan Specific JTAG Instructions
    • EXTEST; $0
    • IDCODE; $1
    • SAMPLE_PRELOAD; $2
    • AVR_RESET; $C
    • BYPASS; $F
    • Boundary-scan Related Register in I/O Memory
    • MCU Control and Status Register – MCUCSR
  • Boundary-scan Chain
    • Scanning the Digital Port Pins
    • Boundary-scan and the Two- wire Interface
    • Scanning the RESET Pin
    • Scanning the Clock Pins
    • Scanning the Analog Comparator
    • Scanning the ADC
  • ATmega16 Boundary- scan Order
  • Boundary-scan Description Language Files
• Boot Loader Support – Read-While-Write Self-Programming
  • Features
  • Application and Boot Loader Flash Sections
    • Application Section
    • BLS – Boot Loader Section
  • Read-While-Write and no Read-While-Write Flash Sections
    • RWW - Read-While-Write section
    • NRWW - No Read-While-Write section
  • Boot Loader Lock Bits
  • Entering the Boot Loader program
    • Store Program Memory Control Register – SPMCR
  • Addressing the Flash during Self- Programming
  • Self-Programming the Flash
    • Performing Page Erase by SPM
    • Filling the Temporary Buffer (Page Loading)
    • Performing a Page Write
    • Using the SPM Interrupt
    • Consideration while Updating BLS
    • Prevent Reading the RWW Section during Self- Programming
    • Setting the Boot Loader Lock Bits by SPM
    • EEPROM Write Prevents Writing to SPMCR
    • Reading the Fuse and Lock Bits from Software
    • Preventing Flash Corruption
    • Programming Time for Flash when using SPM
    • Simple Assembly Code Example for a Boot Loader
    • ATmega16 Boot Loader Parameters
• Memory Programming
  • Program And Data Memory Lock Bits
  • Fuse Bits
    • Latching of Fuses
  • Signature Bytes
  • Calibration Byte
  • Parallel Programming Parameters, Pin Mapping, and Commands
    • Signal Names
  • Parallel Programming
    • Enter Programming Mode
    • Considerations for Efficient Programming
    • Chip Erase
    • Programming the Flash
    • Programming the EEPROM
    • Reading the Flash
    • Reading the EEPROM
    • Programming the Fuse Low Bits
    • Programming the Fuse High Bits
    • Programming the Lock Bits
    • Reading the Fuse and Lock Bits
    • Reading the Signature Bytes
    • Reading the Calibration Byte
    • Parallel Programming Characteristics
  • Serial Downloading
  • Serial Programming Pin Mapping
    • Serial Programming Algorithm
    • Data Polling Flash
    • Data Polling EEPROM
    • Serial Programming Characteristics
  • Programming via the JTAG Interface
    • Programming Specific JTAG Instructions
    • 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 Load 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 Fuses and Lock Bits
    • Reading the Signature Bytes
    • Reading the Calibration Byte
• Electrical Characteristics
  • Absolute Maximum Ratings*
  • External Clock Drive Waveforms
  • External Clock Drive
  • 2-wire Serial Interface Characteristics
  • SPI Timing Characteristics
• ADC Characteristics – Preliminary Data
• ATmega16 Typical Characteristics – Preliminary Data
• Register Summary 
• Ordering Information
• Packaging Information
  • 44A
• 40P6