gex-docs/UNIT_USART.md

USART

This unit provides access to the hardware USART peripheral. It is capable of driving RS485 transceivers.

The unit uses asynchronous reception and transmission using DMA to support low baud rates without lagging the whole platform. Reception is double-buffered and sent in buffer-sized chunks. The remainder is sent when a timeout from the last received byte is reached.

Commands

WRITE (0)

Add data to the Tx buffer. Sending is asynchronous, but the command may wait for free space in the DMA buffer.

Request:

• u8[] - bytes to write

WRITE_SYNC (1)

Add data to the Tx buffer and wait for the transmission to complete.

Request:

• u8[] - bytes to write

Events

DATA_RECEIVED (0)

Data was received on the serial port.

Payload:

• u8[] - received bytes