HAL_UART_TxCpltCallback called only for DMA in circular mode

Participant

HAL_UART_Transmit_DMA and HAL_UART_Receive_DMA differ in that for the receive version, the callback HAL_UART_RxCpltCallback is always called, whereas for the transmit version, HAL_UART_TxCpltCallback is called only when DMA is set to circular mode, see implementation of UART_DMATransmitCplt in stm32f4xx_hal_uart.c.

Why the difference and how do I know when TX is done?

mzaffalon

Participant

You write it at page 282: one should enable the UART interrupt and HAL_UART_TxCpltCallback is called once at the end of the DMA transfer, independently on the DMA mode, whether normal mode of circular.