STM8S datasheet(351/467 Pages) STMICROELECTRONICS

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RM0016

Universal asynchronous receiver transmitter (UART)

377

Figure 131. Break detection in LIN mode vs framing error detection

Response transmission (master is the publisher of the response)

The response is composed of bytes with a standard UART format: 8-bit data, 1 stop bit, no

parity.

In order to send n data bytes, the application must repeat the following sequence n times:

Write data in UART_DR register

Wait for RXNE flag in UART_SR register

Check for readback value by reading the UART_DR register

Response reception (master is the subscriber of the response)

In order to receive n data bytes, the application must repeat following sequence n times:

Wait for the RXNE flag in the UART_SR register

Read the UART_DR register

Discard response (slave to slave communication)

In case of slave to slave communication and if the master does not need to check errors in

the response, the application can ignore the RXNE flag till the next frame slot. The RXNE

and OR flags should be cleared before starting the next Break transmission.

Note:

Receiving back a Break will also set the RXNE and FE flags before setting the LBDF flag.

Therefore, if the RX interrupt is used, it's better to disable it (by clearing the RIEN bit in the

UART_CR2 register) before sending the Break, to avoid an additional interrupt. In case of

slave to slave communication, RIEN bit can be cleared once the header has been

transmitted.

STM8S Datasheet(PDF) 351 Page - STMicroelectronics