ATmega32A datasheet(169/352 Pages) ATMEL

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169

8155B–AVR–07/09

ATmega32A

• Bit 0 – MPCM: Multi-processor Communication Mode

This bit enables the Multi-processor Communication mode. When the MPCM bit is written to

one, all the incoming frames received by the USART receiver that do not contain address infor-

mation will be ignored. The transmitter is unaffected by the MPCM setting. For more detailed

information see “Multi-processor Communication Mode” on page 164.

19.11.3

UCSRB – USART Control and Status Register B

• Bit 7 – RXCIE: RX Complete Interrupt Enable

Writing this bit to one enables interrupt on the RXC Flag. A USART Receive Complete Interrupt

will be generated only if the RXCIE bit is written to one, the Global Interrupt Flag in SREG is writ-

ten to one and the RXC bit in UCSRA is set.

• Bit 6 – TXCIE: TX Complete Interrupt Enable

Writing this bit to one enables interrupt on the TXC Flag. A USART Transmit Complete Interrupt

will be generated only if the TXCIE bit is written to one, the Global Interrupt Flag in SREG is writ-

ten to one and the TXC bit in UCSRA is set.

• Bit 5 – UDRIE: USART Data Register Empty Interrupt Enable

Writing this bit to one enables interrupt on the UDRE Flag. A Data Register Empty Interrupt will

be generated only if the UDRIE bit is written to one, the Global Interrupt Flag in SREG is written

to one and the UDRE bit in UCSRA is set.

• Bit 4 – RXEN: Receiver Enable

Writing this bit to one enables the USART Receiver. The Receiver will override normal port oper-

ation for the RxD pin when enabled. Disabling the Receiver will flush the receive buffer

invalidating the FE, DOR, and PE Flags.

• Bit 3 – TXEN: Transmitter Enable

Writing this bit to one enables the USART Transmitter. The Transmitter will override normal port

operation for the TxD pin when enabled. The disabling of the Transmitter (writing TXEN to zero)

will not become effective until ongoing and pending transmissions are completed, i.e., when the

transmit Shift Register and transmit Buffer Register do not contain data to be transmitted. When

disabled, the transmitter will no longer override the TxD port.

• Bit 2 – UCSZ2: Character Size

The UCSZ2 bits combined with the UCSZ1:0 bit in UCSRC sets the number of data bits (Char-

acter Size) in a frame the receiver and transmitter use.

• Bit 1 – RXB8: Receive Data Bit 8

RXB8 is the ninth data bit of the received character when operating with serial frames with nine

data bits. Must be read before reading the low bits from UDR.

• Bit 0 – TXB8: Transmit Data Bit 8

Bit

765

432

RXCIE

TXCIE

UDRIE

RXEN

TXEN

UCSZ2

RXB8

TXB8

UCSRB

Read/Write

R/W

Initial Value

ATmega32A Datasheet(PDF) 169 Page - ATMEL Corporation

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