topic Re: S32K344 UART DMA example in S32K

S32K344 UART DMA example

S3RD4R — Tue, 17 Jan 2023 00:49:33 GMT

Hello all,

I am using S32K3X4EVB-Q172 development board. I have succesfully implemented interrupt based UART receive however I want to use DMA but i could not find any example. Is there any example of using DMA with UART?

I am using latest MCAL SDK.

Best regards,

Re: S32K344 UART DMA example

PetrS — Tue, 17 Jan 2023 09:06:35 GMT

Hi,

do not have example directly for this board, but see attached demo we got from Apps team.
Hope it helps.

BR, Petr

Re: S32K344 UART DMA example

S3RD4R — Tue, 17 Jan 2023 20:32:39 GMT

Thank you so much. I will check this example further.

Re: S32K344 UART DMA example

S3RD4R — Sat, 21 Jan 2023 00:16:47 GMT

I have completed UART via DMA however i have an interesting case. When i copy captured data to a local variable or global variable and send it via UART, totally corrupt messages are sent. Below i add my code and UART output for reference. Do you have any idea?

Re: S32K344 UART DMA example

PetrS — Mon, 23 Jan 2023 16:33:51 GMT

Hi,

this could be caused by cache. Try to either invalidate the address for the cache of the send buffer or place the buffer in a noncacheable memory.

#pragma GCC section bss ".mcal_bss_no_cacheable" uint8_t tx_data[15]; #pragma GCC section bss

BR, Petr

Re: S32K344 UART DMA example

WellsonGuo — Wed, 22 Feb 2023 02:43:10 GMT

Hello NXP TechSupport,
may I ask another question?

According to this example,
there is only UART1 for receiving and sending data in while loop,

if I add another UART3(interrupt mode) for communicating with this UART1, even if the DMA callback was triggered with event "LPUART_UART_IP_EVENT_END_TRANSFER", my buffer(Rx_Buffer) is still keeping empty, I don't know what's wrong with my procedures.

please help me, thanks~

*This code flow below is fine while interrupt mode.

while(1)
{
lpuartStatus = Lpuart_Uart_Ip_AsyncReceive(UART_LPUART_INTERNAL_CHANNEL_1, Rx_Buffer, length);
if (LPUART_UART_IP_STATUS_SUCCESS != lpuartStatus)
{
return FALSE;
}

//Async send would be OVERRUN during 1.8Mbps baud rate

lpuartStatus = Lpuart_Uart_Ip_SyncSend(UART_LPUART_INTERNAL_CHANNEL_3, Tx_Buffer,length,1000);
if (LPUART_UART_IP_STATUS_SUCCESS != lpuartStatus)
{
return FALSE;
}

do
{
lpuartStatus = Lpuart_Uart_Ip_GetReceiveStatus(UART_LPUART_INTERNAL_CHANNEL_1, &remainingBytes);
} while (LPUART_UART_IP_STATUS_BUSY == lpuartStatus && 0 < T_timeout--);
}

(updated)

If I change the priority of DMA channel(UART RX) from 0 to 2, I can receive part of some message from UART3, like below attachment.