S32K344 UART DMA example

[S3RD4R]

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,

[WellsonGuo]

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.

[S3RD4R]

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?

[PetrS · Accepted solution]

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

[S3RD4R]

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

[PetrS]

Hi,

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

BR, Petr