Kinetis Software Development Kit中的主题 Re: K21 UART4 RX with DMA problem

K21 UART4 RX with DMA problem

jimyang — Fri, 01 Jul 2016 05:38:15 GMT

Hi,

I meet a problem on UART4 Rx with DMA. I tried to modify and build driver_examples\uart\edma_transfer in KSDK2.0.

The modifications as following:

pin_mux.c

CLOCK_EnableClock(kCLOCK_PortC);
PORT_SetPinMux(PORTC, 14U, kPORT_MuxAlt3);
PORT_SetPinMux(PORTC, 15U, kPORT_MuxAlt3);

uart_edma_transfer.c

#define DEMO_UART UART4
#define DEMO_UART_CLKSRC kCLOCK_BusClk
#define UART_TX_DMA_CHANNEL 6U
#define UART_RX_DMA_CHANNEL 7U
#define UART_TX_DMA_REQUEST kDmaRequestMux0UART4
#define UART_RX_DMA_REQUEST kDmaRequestMux0UART4
#define ECHO_BUFFER_LENGTH 8

The test result is: TX is OK, but RX always get same data, g_rxBuffer full fill with the first byte.

I found that when enter DMA IRQ handler first time, UART4 S1[RDRF] is set to 1, then DMA IRQ handler will be called endlessly and RDRF is keep 0.

I also test UART3, it is normal.

Any additional configs are needed for UART4?

Thanks!

Jim Yang

Re: K21 UART4 RX with DMA problem

jimyang — Mon, 04 Jul 2016 06:27:34 GMT

Hi NXP experts,

Any body help to check this problem?

Thanks!

Re: K21 UART4 RX with DMA problem

matthew_rowe — Tue, 05 Nov 2019 09:16:19 GMT

I have the same problem. Removing the transmitter configuration allows the receiver to work fine, so I assume it is something to do with the shared Mux for transmit and receive.

Jim, did you find a solution?

Re: K21 UART4 RX with DMA problem

matthew_rowe — Tue, 05 Nov 2019 09:19:04 GMT

Ok, I found the answer. It's not possible.

https://community.nxp.com/thread/475893