topic Re: UART4/5 can only transmit or receive in DMA mode? in Kinetis Microcontrollers

UART4/5 can only transmit or receive in DMA mode?

jake111 — Thu, 15 Sep 2022 16:59:57 GMT

the DMA request sources

In terms of UART0~UART3,UART Transmit and UART Receive are DMA sources respectively.But UART4~5 only have one source which is UART Transmit or Receive.

Does it mean UART4/5 can't transmit and receive both in DMA mode?Or I have to make sure the process of transmit and receive is at different time.

What should I pay attention to in the program?

1.png

Re: UART4/5 can only transmit or receive in DMA mode?

Ramon_Vega — Mon, 19 Sep 2022 21:46:02 GMT

Hi Vinolzy,

Thank you for contact us, could you please tell me what Kinetis device are you working on?, I am looking for additional details.

Kind Regards

Re: UART4/5 can only transmit or receive in DMA mode?

jake111 — Tue, 20 Sep 2022 06:03:52 GMT

Thanks for your reply.The device is MK64FN1M0VMD12.

Re: UART4/5 can only transmit or receive in DMA mode?

Ramon_Vega — Tue, 20 Sep 2022 19:50:09 GMT

Hi, Vinolzy

You can use DMA on either TX or RX but not both, in K64 both UARTs 4 and 5 have this restriction.

If you connect the source to a DMA channel with both RX and TX DMA triggers enabled either of them will trigger a DMA transfer, which means that RX will disturb TX and TX will disturb RX.

I think that you will need to decide on the direction to use DMA mode and use interrupt on the other.

UARTs: http://www.utasker.com/docs/uTasker/uTaskerUART.PDF

I hope this information help you!.

Kind Regards