Datasheet

Bit 1 – U2X: Double the USART Transmission Speed
This bit only has effect for the asynchronous operation. Write this bit to zero when using synchronous
operation.
Writing this bit to one will reduce the divisor of the baud rate divider from 16 to 8 effectively doubling the
transfer rate for asynchronous communication.
This bit is reserved in Master SPI Mode (MSPIM).
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 n that do not contain address information will be
ignored. The Transmitter is unaffected by the MPCM setting. Refer to Multi-Processor Communication
Mode for details.
This bit is reserved in Master SPI Mode (MSPIM).
Atmel ATmega644A [DATASHEET]
Atmel-42716C-ATmega644A_Datasheet_Complete-10/2016
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