Datasheet
Table Of Contents
- Features
- 1. Pin Configurations
- 2. Overview
- 3. Resources
- 4. Data Retention
- 5. About Code Examples
- 6. Capacitive touch sensing
- 7. AVR CPU Core
- 8. AVR Memories
- 9. System Clock and Clock Options
- 10. Power Management and Sleep Modes
- 11. System Control and Reset
- 12. Interrupts
- 13. I/O Ports
- 13.1 Overview
- 13.2 Ports as General Digital I/O
- 13.3 Alternate Port Functions
- 13.4 Register Description
- 13.4.1 SFIOR – Special Function I/O Register
- 13.4.2 PORTA – Port A Data Register
- 13.4.3 DDRA – Port A Data Direction Register
- 13.4.4 PINA – Port A Input Pins Address
- 13.4.5 PORTB – Port B Data Register
- 13.4.6 DDRB – Port B Data Direction Register
- 13.4.7 PINB – Port B Input Pins Address
- 13.4.8 PORTC – Port C Data Register
- 13.4.9 DDRC – Port C Data Direction Register
- 13.4.10 PINC – Port C Input Pins Address
- 13.4.11 PORTD – Port D Data Register
- 13.4.12 DDRD – Port D Data Direction Register
- 13.4.13 PIND – Port D Input Pins Address
- 14. External Interrupts
- 15. 8-bit Timer/Counter0 with PWM
- 16. Timer/Counter0 and Timer/Counter1 Prescalers
- 17. 16-bit Timer/Counter1
- 17.1 Features
- 17.2 Overview
- 17.3 Accessing 16-bit Registers
- 17.4 Timer/Counter Clock Sources
- 17.5 Counter Unit
- 17.6 Input Capture Unit
- 17.7 Compare Match Output Unit
- 17.8 Modes of Operation
- 17.9 Timer/Counter Timing Diagrams
- 17.10 Register Description
- 17.10.1 TCCR1A – Timer/Counter1 Control Register A
- 17.10.2 TCCR1B – Timer/Counter1 Control Register B
- 17.10.3 TCNT1H and TCNT1L – Timer/Counter1
- 17.10.4 OCR1AH and OCR1AL – Output Compare Register 1 A
- 17.10.5 OCR1BH and OCR1BL – Output Compare Register 1 B
- 17.10.6 ICR1H and ICR1L – Input Capture Register 1
- 17.10.7 TIMSK – Timer/Counter Interrupt Mask Register(1)
- 17.10.8 TIFR – Timer/Counter Interrupt Flag Register
- 18. 8-bit Timer/Counter2 with PWM and Asynchronous Operation
- 18.1 Features
- 18.2 Overview
- 18.3 Timer/Counter Clock Sources
- 18.4 Counter Unit
- 18.5 Output Compare Unit
- 18.6 Compare Match Output Unit
- 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
- 18.11.1 TCCR2 – Timer/Counter Control Register
- 18.11.2 TCNT2 – Timer/Counter Register
- 18.11.3 OCR2 – Output Compare Register
- 18.11.4 ‘ASSR – Asynchronous Status Register
- 18.11.5 TIMSK – Timer/Counter Interrupt Mask Register
- 18.11.6 TIFR – Timer/Counter Interrupt Flag Register
- 18.11.7 SFIOR – Special Function IO Register
- 19. SPI – Serial Peripheral Interface
- 20. USART
- 20.1 Features
- 20.2 Overview
- 20.3 Clock Generation
- 20.4 Frame Formats
- 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
- 20.10 Accessing UBRRH/ UCSRC Registers
- 20.11 Register Description
- 20.12 Examples of Baud Rate Setting
- 21. Two-wire Serial Interface
- 22. Analog Comparator
- 23. Analog to Digital Converter
- 24. JTAG Interface and On-chip Debug System
- 25. IEEE 1149.1 (JTAG) Boundary-scan
- 26. Boot Loader Support – Read-While-Write Self-Programming
- 26.1 Features
- 26.2 Overview
- 26.3 Application and Boot Loader Flash Sections
- 26.4 Read-While-Write and no Read-While-Write Flash Sections
- 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
- 26.8.1 Performing Page Erase by SPM
- 26.8.2 Filling the Temporary Buffer (Page Loading)
- 26.8.3 Performing a Page Write
- 26.8.4 Using the SPM Interrupt
- 26.8.5 Consideration while Updating BLS
- 26.8.6 Prevent Reading the RWW Section during Self-Programming
- 26.8.7 Setting the Boot Loader Lock Bits by SPM
- 26.8.8 EEPROM Write Prevents Writing to SPMCR
- 26.8.9 Reading the Fuse and Lock Bits from Software
- 26.8.10 Preventing Flash Corruption
- 26.8.11 Programming Time for Flash when using SPM
- 26.8.12 Simple Assembly Code Example for a Boot Loader
- 26.8.13 Boot Loader Parameters
- 26.9 Register Description
- 27. Memory Programming
- 27.1 Program And Data Memory Lock Bits
- 27.2 Fuse Bits
- 27.3 Signature Bytes
- 27.4 Calibration Byte
- 27.5 Page Size
- 27.6 Parallel Programming Parameters, Pin Mapping, and Commands
- 27.7 Parallel Programming
- 27.7.1 Enter Programming Mode
- 27.7.2 Considerations for Efficient Programming
- 27.7.3 Chip Erase
- 27.7.4 Programming the Flash
- 27.7.5 Programming the EEPROM
- 27.7.6 Reading the Flash
- 27.7.7 Reading the EEPROM
- 27.7.8 Programming the Fuse Low Bits
- 27.7.9 Programming the Fuse High Bits
- 27.7.10 Programming the Lock Bits
- 27.7.11 Reading the Fuse and Lock Bits
- 27.7.12 Reading the Signature Bytes
- 27.7.13 Reading the Calibration Byte
- 27.7.14 Parallel Programming Characteristics
- 27.8 SPI Serial Downloading
- 27.9 SPI Serial Programming Pin Mapping
- 27.10 Programming via the JTAG Interface
- 27.10.1 Programming Specific JTAG Instructions
- 27.10.2 AVR_RESET ($C)
- 27.10.3 PROG_ENABLE ($4)
- 27.10.4 PROG_COMMANDS ($5)
- 27.10.5 PROG_PAGELOAD ($6)
- 27.10.6 PROG_PAGEREAD ($7)
- 27.10.7 Data Registers
- 27.10.8 Reset Register
- 27.10.9 Programming Enable Register
- 27.10.10 Programming Command Register
- 27.10.11 Virtual Flash Page Load Register
- 27.10.12 Virtual Flash Page Read Register
- 27.10.13 Programming Algorithm
- 27.10.14 Entering Programming Mode
- 27.10.15 Leaving Programming Mode
- 27.10.16 Performing Chip Erase
- 27.10.17 Programming the Flash
- 27.10.18 Reading the Flash
- 27.10.19 Programming the EEPROM
- 27.10.20 Reading the EEPROM
- 27.10.21 Programming the Fuses
- 27.10.22 Programming the Lock Bits
- 27.10.23 Reading the Fuses and Lock Bits
- 27.10.24 Reading the Signature Bytes
- 27.10.25 Reading the Calibration Byte
- 28. Electrical 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
- 34. Errata
- 35. Datasheet Revision History
- Table of Contents
148
ATmega32A [DATASHEET]
Atmel-8155D-AVR-ATmega32A-Datasheet_02/2014
20.7.3 Receive Compete Flag and Interrupt
The USART Receiver has one flag that indicates the receiver state.
The Receive Complete (RXC) Flag indicates if there are unread data present in the receive buffer. This flag is one
when unread data exist in the receive buffer, and zero when the receive buffer is empty (that is, does not contain
any unread data). If the receiver is disabled (RXEN = 0), the receive buffer will be flushed and consequently the
RXC bit will become zero.
When the Receive Complete Interrupt Enable (RXCIE) in UCSRB is set, the USART Receive Complete Interrupt
will be executed as long as the RXC Flag is set (provided that global interrupts are enabled). When interrupt-driven
data reception is used, the receive complete routine must read the received data from UDR in order to clear the
RXC Flag, otherwise a new interrupt will occur once the interrupt routine terminates.
20.7.4 Receiver Error Flags
The USART Receiver has three Error Flags: Frame Error (FE), Data OverRun (DOR) and Parity Error (PE). All can
be accessed by reading UCSRA. Common for the Error Flags is that they are located in the receive buffer together
with the frame for which they indicate the error status. Due to the buffering of the Error Flags, the UCSRA must be
read before the receive buffer (UDR), since reading the UDR I/O location changes the buffer read location. Another
equality for the Error Flags is that they can not be altered by software doing a write to the flag location. However, all
flags must be set to zero when the UCSRA is written for upward compatibility of future USART implementations.
None of the Error Flags can generate interrupts.
The Frame Error (FE) Flag indicates the state of the first stop bit of the next readable frame stored in the receive
buffer. The FE Flag is zero when the stop bit was correctly read (as one), and the FE Flag will be one when the
stop bit was incorrect (zero). This flag can be used for detecting out-of-sync conditions, detecting break conditions
and protocol handling. The FE Flag is not affected by the setting of the USBS bit in UCSRC since the receiver
ignores all, except for the first, stop bits. For compatibility with future devices, always set this bit to zero when writ-
ing to UCSRA.
The Data OverRun (DOR) Flag indicates data loss due to a receiver buffer full condition. A Data OverRun occurs
when the receive buffer is full (two characters), it is a new character waiting in the receive Shift Register, and a new
start bit is detected. If the DOR Flag is set there was one or more serial frame lost between the frame last read
from UDR, and the next frame read from UDR. For compatibility with future devices, always write this bit to zero
when writing to UCSRA. The DOR Flag is cleared when the frame received was successfully moved from the Shift
Register to the receive buffer.
The Parity Error (PE) Flag indicates that the next frame in the receive buffer had a parity error when received. If
parity check is not enabled the PE bit will always be read zero. For compatibility with future devices, always set this
bit to zero when writing to UCSRA. For more details see “Parity Bit Calculation” on page 153 and “Parity Checker”
on page 160.
20.7.5 Parity Checker
The Parity Checker is active when the high USART Parity mode (UPM1) bit is set. Type of parity check to be per-
formed (odd or even) is selected by the UPM0 bit. When enabled, the parity checker calculates the parity of the
data bits in incoming frames and compares the result with the parity bit from the serial frame. The result of the
check is stored in the receive buffer together with the received data and stop bits. The Parity Error (PE) Flag can
then be read by software to check if the frame had a parity error.
The PE bit is set if the next character that can be read from the receive buffer had a parity error when received and
the parity checking was enabled at that point (UPM1 = 1). This bit is valid until the receive buffer (UDR) is read.
20.7.6 Disabling the Receiver
In contrast to the Transmitter, disabling of the Receiver will be immediate. Data from ongoing receptions will there-
fore be lost. When disabled (that is, the RXEN is set to zero) the Receiver will no longer override the normal