Datasheet
Table Of Contents
- Introduction
- Features
- Table of Contents
- 1. Description
- 2. Configuration Summary
- 3. Ordering Information
- 4. Block Diagram
- 5. Pin Configurations
- 6. Resources
- 7. Data Retention
- 8. About Code Examples
- 9. Capacitive Touch Sensing
- 10. AVR CPU Core
- 11. AVR Memories
- 12. System Clock and Clock Options
- 13. Power Management and Sleep Modes
- 14. System Control and Reset
- 15. Interrupts
- 16. External Interrupts
- 17. I/O Ports
- 17.1. Overview
- 17.2. Ports as General Digital I/O
- 17.3. Alternate Port Functions
- 17.4. Register Description
- 17.4.1. SFIOR – Special Function IO Register
- 17.4.2. PORTA – Port A Data Register
- 17.4.3. DDRA – Port A Data Direction Register
- 17.4.4. PINA – Port A Input Pins Address
- 17.4.5. PORTB – The Port B Data Register
- 17.4.6. DDRB – The Port B Data Direction Register
- 17.4.7. PINB – The Port B Input Pins Address
- 17.4.8. PORTC – The Port C Data Register
- 17.4.9. DDRC – The Port C Data Direction Register
- 17.4.10. PINC – The Port C Input Pins Address
- 17.4.11. PORTD – The Port D Data Register
- 17.4.12. DDRD – The Port D Data Direction Register
- 17.4.13. PIND – The Port D Input Pins Address
- 18. Timer/Counter0 and Timer/Counter1 Prescalers
- 19. 16-bit Timer/Counter1
- 19.1. Features
- 19.2. Overview
- 19.3. Accessing 16-bit Registers
- 19.4. Timer/Counter Clock Sources
- 19.5. Counter Unit
- 19.6. Input Capture Unit
- 19.7. Output Compare Units
- 19.8. Compare Match Output Unit
- 19.9. Modes of Operation
- 19.10. Timer/Counter Timing Diagrams
- 19.11. Register Description
- 19.11.1. TCCR1A – Timer/Counter1 Control Register A
- 19.11.2. TCCR1B – Timer/Counter1 Control Register B
- 19.11.3. TCNT1L – Timer/Counter1 Low byte
- 19.11.4. TCNT1H – Timer/Counter1 High byte
- 19.11.5. OCR1AL – Output Compare Register 1 A Low byte
- 19.11.6. OCR1AH – Output Compare Register 1 A High byte
- 19.11.7. OCR1BL – Output Compare Register 1 B Low byte
- 19.11.8. OCR1BH – Output Compare Register 1 B High byte
- 19.11.9. ICR1L – Input Capture Register 1 Low byte
- 19.11.10. ICR1H – Input Capture Register 1 High byte
- 19.11.11. TIMSK – Timer/Counter Interrupt Mask Register
- 19.11.12. TIFR – Timer/Counter Interrupt Flag Register
- 20. 8-bit Timer/Counter2 with PWM and Asynchronous Operation
- 20.1. Features
- 20.2. Overview
- 20.3. Timer/Counter Clock Sources
- 20.4. Counter Unit
- 20.5. Output Compare Unit
- 20.6. Compare Match Output Unit
- 20.7. Modes of Operation
- 20.8. Timer/Counter Timing Diagrams
- 20.9. Asynchronous Operation of the Timer/Counter
- 20.10. Timer/Counter Prescaler
- 20.11. Register Description
- 20.11.1. TCCR2 – Timer/Counter Control Register
- 20.11.2. TCNT0 – Timer/Counter Register
- 20.11.3. OCR0 – Output Compare Register
- 20.11.4. ASSR – Asynchronous Status Register
- 20.11.5. TIMSK – Timer/Counter Interrupt Mask Register
- 20.11.6. TIFR – Timer/Counter Interrupt Flag Register
- 20.11.7. SFIOR – Special Function IO Register
- 21. 8-bit Timer/Counter0 with PWM
- 22. SPI – Serial Peripheral Interface
- 23. USART - Universal Synchronous and Asynchronous serial Receiver and Transmitter
- 23.1. Features
- 23.2. Overview
- 23.3. Clock Generation
- 23.4. Frame Formats
- 23.5. USART Initialization
- 23.6. Data Transmission – The USART Transmitter
- 23.7. Data Reception – The USART Receiver
- 23.8. Asynchronous Data Reception
- 23.9. Multi-Processor Communication Mode
- 23.10. Accessing UBRRH/UCSRC Registers
- 23.11. Register Description
- 23.12. Examples of Baud Rate Setting
- 24. TWI - Two-wire Serial Interface
- 25. AC - Analog Comparator
- 26. ADC - Analog to Digital Converter
- 26.1. Features
- 26.2. Overview
- 26.3. Starting a Conversion
- 26.4. Prescaling and Conversion Timing
- 26.5. Changing Channel or Reference Selection
- 26.6. ADC Noise Canceler
- 26.7. ADC Conversion Result
- 26.8. Register Description
- 26.8.1. ADMUX – ADC Multiplexer Selection Register
- 26.8.2. ADCSRA – ADC Control and Status Register A
- 26.8.3. ADCL – ADC Data Register Low (ADLAR=0)
- 26.8.4. ADCH – ADC Data Register High (ADLAR=0)
- 26.8.5. ADCL – ADC Data Register Low (ADLAR=1)
- 26.8.6. ADCH – ADC Data Register High (ADLAR=1)
- 26.8.7. SFIOR – Special Function IO Register
- 27. JTAG Interface and On-chip Debug System
- 27.1. Features
- 27.2. Overview
- 27.3. TAP – Test Access Port
- 27.4. TAP Controller
- 27.5. Using the Boundary-scan Chain
- 27.6. Using the On-chip Debug System
- 27.7. On-chip Debug Specific JTAG Instructions
- 27.8. Using the JTAG Programming Capabilities
- 27.9. Bibliography
- 27.10. IEEE 1149.1 (JTAG) Boundary-scan
- 27.11. Data Registers
- 27.12. Boundry-scan Specific JTAG Instructions
- 27.13. Boundary-scan Chain
- 27.14. ATmega32A Boundary-scan Order
- 27.15. Boundary-scan Description Language Files
- 27.16. Register Description
- 28. BTLDR - Boot Loader Support – Read-While-Write Self-Programming
- 28.1. Features
- 28.2. Overview
- 28.3. Application and Boot Loader Flash Sections
- 28.4. Read-While-Write and No Read-While-Write Flash Sections
- 28.5. Boot Loader Lock Bits
- 28.6. Entering the Boot Loader Program
- 28.7. Addressing the Flash During Self-Programming
- 28.8. Self-Programming the Flash
- 28.8.1. Performing Page Erase by SPM
- 28.8.2. Filling the Temporary Buffer (Page Loading)
- 28.8.3. Performing a Page Write
- 28.8.4. Using the SPM Interrupt
- 28.8.5. Consideration While Updating Boot Loader Section (BLS)
- 28.8.6. Prevent Reading the RWW Section During Self-Programming
- 28.8.7. Setting the Boot Loader Lock Bits by SPM
- 28.8.8. EEPROM Write Prevents Writing to SPMCR
- 28.8.9. Reading the Fuse and Lock Bits from Software
- 28.8.10. Preventing Flash Corruption
- 28.8.11. Programming Time for Flash when Using SPM
- 28.8.12. Simple Assembly Code Example for a Boot Loader
- 28.8.13. ATmega32A Boot Loader Parameters
- 28.9. Register Description
- 29. Memory Programming
- 29.1. Program and Data Memory Lock Bits
- 29.2. Fuse Bits
- 29.3. Signature Bytes
- 29.4. Signature Bytes
- 29.5. Calibration Byte
- 29.6. Parallel Programming Parameters, Pin Mapping, and Commands
- 29.7. Parallel Programming
- 29.7.1. Enter Programming Mode
- 29.7.2. Considerations for Efficient Programming
- 29.7.3. Chip Erase
- 29.7.4. Programming the Flash
- 29.7.5. Programming the EEPROM
- 29.7.6. Reading the Flash
- 29.7.7. Reading the EEPROM
- 29.7.8. Programming the Fuse Low Bits
- 29.7.9. Programming the Fuse High Bits
- 29.7.10. Programming the Lock Bits
- 29.7.11. Reading the Fuse and Lock Bits
- 29.7.12. Reading the Signature Bytes
- 29.7.13. Reading the Calibration Byte
- 29.7.14. Parallel Programming Characteristics
- 29.8. Serial Downloading
- 29.9. Serial Programming Pin Mapping
- 29.10. Programming Via the JTAG Interface
- 29.10.1. Programming Specific JTAG Instructions
- 29.10.2. AVR_RESET (0xC)
- 29.10.3. PROG_ENABLE (0x4)
- 29.10.4. PROG_COMMANDS (0x5)
- 29.10.5. PROG_PAGELOAD (0x6)
- 29.10.6. PROG_PAGEREAD (0x7)
- 29.10.7. Data Registers
- 29.10.8. Reset Register
- 29.10.9. Programming Enable Register
- 29.10.10. Programming Command Register
- 29.10.11. Virtual Flash Page Load Register
- 29.10.12. Virtual Flash Page Read Register
- 29.10.13. Programming Algorithm
- 29.10.14. Entering Programming Mode
- 29.10.15. Leaving Programming Mode
- 29.10.16. Performing Chip Erase
- 29.10.17. Programming the Flash
- 29.10.18. Reading the Flash
- 29.10.19. Programming the EEPROM
- 29.10.20. Reading the EEPROM
- 29.10.21. Programming the Fuses
- 29.10.22. Programming the Lock Bits
- 29.10.23. Reading the Fuses and Lock Bits
- 29.10.24. Reading the Signature Bytes
- 29.10.25. Reading the Calibration Byte
- 30. Electrical Characteristics
- 31. Typical Characteristics
- 31.1. Active Supply Current
- 31.2. Idle Supply Current
- 31.3. Power-down Supply Current
- 31.4. Power-save Supply current
- 31.5. Standby Supply Current
- 31.6. Pin Pull-up
- 31.7. Pin Driver Strength
- 31.8. Pin Thresholds and Hysteresis
- 31.9. BOD Thresholds and Analog Comparator Offset
- 31.10. Internal Oscillator Speed
- 31.11. Current Consumption of Peripheral Units
- 31.12. Current Consumption in Reset and Reset Pulsewidth
- 32. Register Summary
- 33. Instruction Set Summary
- 34. Packaging Information
- 35. Errata
- 36. Datasheet Revision History
Table 23-1. Equations for Calculating Baud Rate Register Setting
Operating Mode Equation for Calculating Baud
Rate
(1)
Equation for Calculating UBRR
Value
Asynchronous Normal
mode (U2X = 0)
BAUD =
OSC
16
+ 1
=
OSC
16BAUD
1
Asynchronous Double
Speed mode (U2X = 1)
BAUD =
OSC
8
+ 1
=
OSC
8BAUD
1
Synchronous Master mode
BAUD =
OSC
2
+1
=
OSC
2BAUD
1
Note: 1. The baud rate is defined to be the transfer rate in bit per second (bps).
BAUD Baud rate (in bits per second, bps).
f
OSC
System oscillator clock frequency.
UBRR Contents of the UBRRH and UBRRL Registers, (0-4095).
Some examples of UBRR values for some system clock frequencies are found in Table 23-9.
23.3.2. Double Speed Operation (U2X)
The transfer rate can be doubled by setting the U2X bit in UCSRA. Setting this bit only has effect for the
asynchronous operation. Set this bit to zero when using synchronous operation.
Setting this bit will reduce the divisor of the baud rate divider from 16 to 8, effectively doubling the transfer
rate for asynchronous communication. Note however that the Receiver will in this case only use half the
number of samples (reduced from 16 to 8) for data sampling and clock recovery, and therefore a more
accurate baud rate setting and system clock are required when this mode is used.
For the Transmitter, there are no downsides.
23.3.3. External Clock
External clocking is used by the synchronous slave modes of operation. The description in this section
refers to Figure 23-2.
External clock input from the XCK pin is sampled by a synchronization register to minimize the chance of
meta-stability. The output from the synchronization register must then pass through an edge detector
before it can be used by the Transmitter and Receiver. This process introduces a two CPU clock period
delay and therefore the maximum external XCK clock frequency is limited by the following equation:
XCK
<
OSC
4
The value of f
osc
depends on the stability of the system clock source. It is therefore recommended to add
some margin to avoid possible loss of data due to frequency variations.
23.3.4. Synchronous Clock Operation
When Synchronous mode is used (UMSEL = 1), the XCK pin will be used as either clock input (Slave) or
clock output (Master). The dependency between the clock edges and data sampling or data change is the
same. The basic principle is that data input (on RxD) is sampled at the opposite XCK clock edge of the
edge the data output (TxD) is changed.
Atmel ATmega32A [DATASHEET]
Atmel-8155I-ATmega32A_Datasheet_Complete-08/2016
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