Datasheet

ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller VQFN 44 (7x7) 8-Bit 16 MHz I/O number 32

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Table Of Contents

Features
1. Pin Configurations
2. Overview
- 2.1 Block Diagram
- 2.2 Pin Descriptions
3. Resources
4. Data Retention
5. About Code Examples
6. Capacitive touch sensing
7. AVR CPU Core
- 7.1 Overview
- 7.2 ALU – Arithmetic Logic Unit
- 7.3 Status Register
  - 7.3.1 SREG – AVR Status Register
- 7.4 General Purpose Register File
  - 7.4.1 The X-register, Y-register and Z-register
- 7.5 Stack Pointer
  - 7.5.1 SPH and SPL – Stack Pointer High and Low Register
- 7.6 Instruction Execution Timing
- 7.7 Reset and Interrupt Handling
  - 7.7.1 Interrupt Response Time
8. AVR Memories
- 8.1 Overview
- 8.2 In-System Reprogrammable Flash Program Memory
- 8.3 SRAM Data Memory
  - 8.3.1 Data Memory Access Times
- 8.4 EEPROM Data Memory
- 8.5 I/O Memory
- 8.6 Register Description
9. System Clock and Clock Options
- 9.1 Clock Systems and their Distribution
- 9.2 Clock Sources
- 9.3 Default Clock Source
- 9.4 Crystal Oscillator
- 9.5 Low-frequency Crystal Oscillator
- 9.6 External RC Oscillator
- 9.7 Calibrated Internal RC Oscillator
- 9.8 External Clock
- 9.9 Timer/Counter Oscillator
- 9.10 Register Description
  - 9.10.1 OSCCAL – Oscillator Calibration Register
10. Power Management and Sleep Modes
- 10.1 Sleep Modes
- 10.2 Idle Mode
- 10.3 ADC Noise Reduction Mode
- 10.4 Power-down Mode
- 10.5 Power-save Mode
- 10.6 Standby Mode
- 10.7 Extended Standby Mode
- 10.8 Minimizing Power Consumption
- 10.9 Register Description
  - 10.9.1 MCUCR – MCU Control Register
11. System Control and Reset
- 11.1 Resetting the AVR
- 11.2 Reset Sources
- 11.3 Internal Voltage Reference
  - 11.3.1 Voltage Reference Enable Signals and Start-up Time
- 11.4 Watchdog Timer
- 11.5 Register Description
  - 11.5.1 MCUCSR – MCU Control and Status Register
  - 11.5.2 WDTCR – Watchdog Timer Control Register
12. Interrupts
- 12.1 Interrupt Vectors in ATmega32A
  - 12.1.1 Moving Interrupts Between Application and Boot Space
- 12.2 Register Description
  - 12.2.1 GICR – General Interrupt Control Register
13. I/O Ports
- 13.1 Overview
- 13.2 Ports as General Digital I/O
- 13.3 Alternate Port Functions
- 13.4 Register Description
14. External Interrupts
- 14.1 Register Description
15. 8-bit Timer/Counter0 with PWM
- 15.1 Features
- 15.2 Overview
  - 15.2.1 Registers
  - 15.2.2 Definitions
- 15.3 Timer/Counter Clock Sources
- 15.4 Counter Unit
- 15.5 Output Compare Unit
- 15.6 Compare Match Output Unit
  - 15.6.1 Compare Output Mode and Waveform Generation
- 15.7 Modes of Operation
- 15.8 Timer/Counter Timing Diagrams
- 15.9 Register Description
16. Timer/Counter0 and Timer/Counter1 Prescalers
- 16.1 Overview
- 16.2 Internal Clock Source
- 16.3 Prescaler Reset
- 16.4 External Clock Source
- 16.5 Register Description
  - 16.5.1 SFIOR – Special Function IO Register
17. 16-bit Timer/Counter1
- 17.1 Features
- 17.2 Overview
- 17.3 Accessing 16-bit Registers
  - 17.3.1 Reusing the Temporary High Byte Register
- 17.4 Timer/Counter Clock Sources
- 17.5 Counter Unit
- 17.6 Input Capture Unit
- 17.7 Compare Match Output Unit
  - 17.7.1 Compare Output Mode and Waveform Generation
- 17.8 Modes of Operation
- 17.9 Timer/Counter Timing Diagrams
- 17.10 Register Description
18. 8-bit Timer/Counter2 with PWM and Asynchronous Operation
- 18.1 Features
- 18.2 Overview
  - 18.2.1 Registers
  - 18.2.2 Definitions
- 18.3 Timer/Counter Clock Sources
- 18.4 Counter Unit
- 18.5 Output Compare Unit
- 18.6 Compare Match Output Unit
  - 18.6.1 Compare Output Mode and Waveform Generation
- 18.7 Modes of Operation
- 18.8 Timer/Counter Timing Diagrams
- 18.9 Asynchronous Operation of the Timer/Counter
- 18.10 Timer/Counter Prescaler
- 18.11 Register Description
19. SPI – Serial Peripheral Interface
- 19.1 Features
- 19.2 Overview
- 19.3 SS Pin Functionality
- 19.4 Data Modes
20. USART
- 20.1 Features
- 20.2 Overview
  - 20.2.1 AVR USART vs. AVR UART – Compatibility
- 20.3 Clock Generation
- 20.4 Frame Formats
  - 20.4.1 Parity Bit Calculation
- 20.5 USART Initialization
- 20.6 Data Transmission – The USART Transmitter
- 20.7 Data Reception – The USART Receiver
- 20.8 Asynchronous Data Reception
- 20.9 Multi-processor Communication Mode
  - 20.9.1 Using MPCM
- 20.10 Accessing UBRRH/ UCSRC Registers
  - 20.10.1 Write Access
  - 20.10.2 Read Access
- 20.11 Register Description
- 20.12 Examples of Baud Rate Setting
21. Two-wire Serial Interface
- 21.1 Features
- 21.2 Two-wire Serial Interface Bus Definition
  - 21.2.1 TWI Terminology
  - 21.2.2 Electrical Interconnection
- 21.3 Data Transfer and Frame Format
- 21.4 Multi-master Bus Systems, Arbitration and Synchronization
- 21.5 Overview of the TWI Module
- 21.6 Using the TWI
- 21.7 Transmission Modes
- 21.8 Multi-master Systems and Arbitration
- 21.9 Register Description
22. Analog Comparator
- 22.1 Overview
- 22.2 Analog Comparator Multiplexed Input
- 22.3 Register Description
  - 22.3.1 SFIOR – Special Function IO Register
  - 22.3.2 ACSR – Analog Comparator Control and Status Register
23. Analog to Digital Converter
- 23.1 Features
- 23.2 Overview
- 23.3 Operation
- 23.4 Starting a Conversion
- 23.5 Prescaling and Conversion Timing
  - 23.5.1 Differential Gain Channels
- 23.6 Changing Channel or Reference Selection
  - 23.6.1 ADC Input Channels
  - 23.6.2 ADC Voltage Reference
- 23.7 ADC Noise Canceler
- 23.8 ADC Conversion Result
- 23.9 Register Description
24. JTAG Interface and On-chip Debug System
- 24.1 Features
- 24.2 Overview
- 24.3 TAP – Test Access Port
- 24.4 TAP Controller
- 24.5 Using the Boundary-scan Chain
- 24.6 Using the On-chip Debug System
- 24.7 On-chip Debug Specific JTAG Instructions
- 24.8 Using the JTAG Programming Capabilities
- 24.9 Register Description
  - 24.9.1 OCDR – On-chip Debug Register
- 24.10 Bibliography
25. IEEE 1149.1 (JTAG) Boundary-scan
- 25.1 Features
- 25.2 Overview
- 25.3 Data Registers
- 25.4 Boundary-scan Specific JTAG Instructions
- 25.5 Boundary-scan Chain
- 25.6 ATmega32A Boundary-scan Order
- 25.7 Boundary-scan Description Language Files
- 25.8 Register Description
  - 25.8.1 MCU Control and Status Register – MCUCSR
26. Boot Loader Support – Read-While-Write Self-Programming
- 26.1 Features
- 26.2 Overview
- 26.3 Application and Boot Loader Flash Sections
  - 26.3.1 Application Section
  - 26.3.2 BLS – Boot Loader Section
- 26.4 Read-While-Write and no Read-While-Write Flash Sections
  - 26.4.1 RWW – Read-While-Write Section
  - 26.4.2 NRWW – No Read-While-Write Section
- 26.5 Boot Loader Lock Bits
- 26.6 Entering the Boot Loader Program
- 26.7 Addressing the Flash during Self-Programming
- 26.8 Self-Programming the Flash
- 26.9 Register Description
  - 26.9.1 SPMCR – Store Program Memory Control Register
27. Memory Programming
- 27.1 Program And Data Memory Lock Bits
- 27.2 Fuse Bits
  - 27.2.1 Latching of Fuses
- 27.3 Signature Bytes
- 27.4 Calibration Byte
- 27.5 Page Size
- 27.6 Parallel Programming Parameters, Pin Mapping, and Commands
  - 27.6.1 Signal Names
- 27.7 Parallel Programming
- 27.8 SPI Serial Downloading
- 27.9 SPI Serial Programming Pin Mapping
- 27.10 Programming via the JTAG Interface
28. Electrical Characteristics
- 28.1 Absolute Maximum Ratings*
- 28.2 DC Characteristics
- 28.3 Speed Grades
- 28.4 Clock Characteristics
  - 28.4.1 External Clock Drive Waveforms
  - 28.4.2 External Clock Drive
- 28.5 System and Reset Characteristics
- 28.6 Two-wire Serial Interface Characteristics
- 28.7 SPI Timing Characteristics
- 28.8 ADC Characteristics
29. Typical Characteristics
- 29.1 Active Supply Current
- 29.2 Idle Supply Current
- 29.3 Power-down Supply Current
- 29.4 Power-save Supply Current
- 29.5 Standby Supply Current
- 29.6 Pin Pull-up
- 29.7 Pin Driver Strength
- 29.8 Pin Thresholds and Hysteresis
- 29.9 BOD Thresholds and Analog Comparator Offset
- 29.10 Internal Oscillator Speed
- 29.11 Current Consumption of Peripheral Units
- 29.12 Current Consumption in Reset and Reset Pulsewidth
30. Register Summary
31. Instruction Set Summary
32. Ordering Information
33. Packaging Information
- 33.1 44A
- 33.2 40P6
- 33.3 44M1
34. Errata
- 34.1 ATmega32A, rev. J to rev. K
- 34.2 ATmega32A, rev. G to rev. I
35. Datasheet Revision History
- 35.1 Rev. 8155E – 02/2014
- 35.2 Rev. 8155D – 10/2013
- 35.3 Rev. 8155C – 02/2011
- 35.4 Rev. 8155B – 07/2009
- 35.5 Rev. 8155A – 06/2008
Table of Contents

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ATmega32A [DATASHEET]

Atmel-8155D-AVR-ATmega32A-Datasheet_02/2014

St Start bit, always low.

(n) Data bits (0 to 8).

P Parity bit. Can be odd or even.

Sp Stop bit, always high.

IDLE No transfers on the communication line (RxD or TxD). An IDLE line must be

high.

The frame format used by the USART is set by the UCSZ2:0, UPM1:0, and USBS bits in UCSRB and UCSRC. The

Receiver and Transmitter use the same setting. Note that changing the setting of any of these bits will corrupt all

ongoing communication for both the Receiver and Transmitter.

The USART Character SiZe (UCSZ2:0) bits select the number of data bits in the frame. The USART Parity mode

(UPM1:0) bits enable and set the type of parity bit. The selection between one or two stop bits is done by the

USART Stop Bit Select (USBS) bit. The receiver ignores the second stop bit. An FE (Frame Error) will therefore

only be detected in the cases where the first stop bit is zero.

20.4.1 Parity Bit Calculation

The parity bit is calculated by doing an exclusive-or of all the data bits. If odd parity is used, the result of the exclu-

sive or is inverted. The relation between the parity bit and data bits is as follows::

even

Parity bit using even parity

odd

Parity bit using odd parity

Data bit n of the character

If used, the parity bit is located between the last data bit and first stop bit of a serial frame.

20.5 USART Initialization

The USART has to be initialized before any communication can take place. The initialization process normally con-

sists of setting the baud rate, setting frame format and enabling the Transmitter or the Receiver depending on the

usage. For interrupt driven USART operation, the Global Interrupt Flag should be cleared (and interrupts globally

disabled) when doing the initialization.

Before doing a re-initialization with changed baud rate or frame format, be sure that there are no ongoing transmis-

sions during the period the registers are changed. The TXC Flag can be used to check that the Transmitter has

completed all transfers, and the RXC Flag can be used to check that there are no unread data in the receive buffer.

Note that the TXC Flag must be cleared before each transmission (before UDR is written) if it is used for this

purpose.

The following simple USART initialization code examples show one assembly and one C function that are equal in

functionality. The examples assume asynchronous operation using polling (no interrupts enabled) and a fixed

frame format. The baud rate is given as a function parameter. For the assembly code, the baud rate parameter is

assumed to be stored in the r17:r16 registers. When the function writes to the UCSRC Register, the URSEL bit

(MSB) must be set due to the sharing of I/O location by UBRRH and UCSRC.

even

n 1–

 d

odd



n 1–

 d

1