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

[jake111]

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?

[Ramon_Vega · Accepted solution]

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 

[jake111]

Thanks for your reply.The device is MK64FN1M0VMD12.

[Ramon_Vega]

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