AM2634: Uart receive interrupt in DMA mode

Hi Rohal,

Can you please explain what is "continuously" means here, using while loop for UART_read API?

Regards,

Anil

continuously mean after getting 8 byte (threshold set value) it should be get ready to receive next 8 byte and so on, because existing example code works only one time I need it for finitely.

And Please let me know how to receive variable length data on UART, because as per my application USER can send variable size of data means some times he can send 10, 20 or 50 bytes   

Hi Rohal,

Rohal said:

continuously mean after getting 8 byte (threshold set value) it should be get ready to receive next 8 byte and so on, because existing example code works only one time I need it for finitely.

Right now the application is designed to take 8B input from user, then echo back the same 8B and exit the application, You will have to modify the application to keep receiving data (for e.g. in a While loop, keep receiving data).

Regards,
Shaunak

I tried that also but its not receiving any interrupt after getting 8 bytes, So do we need to clear any interrupt flag to make it run again

 CacheP_wbInv((void *)&gUartReceiveBuffer[0U], APP_UART_RECEIVE_BUFSIZE, CacheP_TYPE_ALL); 

above api blocking my process, please let me know how to remove Cache and get the interrupt on every receive the byte 

Can we use DMA with Interrupt mean for transmission get interrupt after sending the all data and for reception get interrupt after getting data(all transmission and reception happen by DMA only) 

Yes, please look into this ASAP,

one more issue noticed here,

I configure 5 byte receive interrupt in DMA mode and its working fine for 5 bytes only, if user send more than 5 bytes lets 6, it's stopped receiving interrupt, 

i'm share the code also please check

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/* This example demonstrates the UART RX and TX operation by echoing char
 * that it recieves in blocking, interrupt mode of operation.
 * When user types 'quit', the application ends.
 */

#include <string.h>
#include <kernel/dpl/DebugP.h>
#include "ti_drivers_config.h"
#include "ti_drivers_open_close.h"
#include "ti_board_open_close.h"


#define APP_UART_BUFSIZE              (200U)
#define APP_UART_RECEIVE_BUFSIZE      (20U)

uint8_t gUartBuffer[APP_UART_BUFSIZE] __attribute__((aligned(CacheP_CACHELINE_ALIGNMENT)));
uint8_t gUartReceiveBuffer[APP_UART_RECEIVE_BUFSIZE] __attribute__((aligned(CacheP_CACHELINE_ALIGNMENT)));
volatile uint32_t gNumBytesRead = 0U, gNumBytesWritten = 0U;

#define APP_UART_ASSERT_ON_FAILURE(transferOK, transaction) \
    do { \
        if((SystemP_SUCCESS != (transferOK)) || (UART_TRANSFER_STATUS_SUCCESS != transaction.status)) \
        { \
            DebugP_assert(FALSE); /* UART TX/RX failed!! */ \
        } \
    } while(0) \


static SemaphoreP_Object gUartWriteDoneSem;
static SemaphoreP_Object gUartReadDoneSem;
static uint8_t rxcomplete=0;
void uart_echo_dma(void *args)
{
    int32_t          transferOK, status;
    UART_Transaction trans;
    UART_Transaction transRx;

    Drivers_open();
    Board_driversOpen();

    DebugP_log("[UART] Echo example DMA mode started ...\r\n");

    status = SemaphoreP_constructBinary(&gUartWriteDoneSem, 0);
    DebugP_assert(SystemP_SUCCESS == status);

    status = SemaphoreP_constructBinary(&gUartReadDoneSem, 0);
    DebugP_assert(SystemP_SUCCESS == status);
    UART_Transaction_init(&trans);
    UART_Transaction_init(&transRx);

    /* Send entry string */
    gNumBytesWritten = 0U;
    trans.buf   = &gUartBuffer[0U];
    strncpy(trans.buf,"This is uart echo test DMA blocking mode\r\nReceives 8 characters then echo's back. Please input..\r\n", APP_UART_BUFSIZE);
    trans.count = strlen(trans.buf);
    CacheP_wb((void *)trans.buf, trans.count, CacheP_TYPE_ALL);
    transferOK = UART_write(gUartHandle[CONFIG_UART_CONSOLE], &trans);

    APP_UART_ASSERT_ON_FAILURE(transferOK, trans);
    SemaphoreP_pend(&gUartWriteDoneSem, SystemP_NO_WAIT);

    CacheP_wbInv((void *)&gUartReceiveBuffer[0U], APP_UART_RECEIVE_BUFSIZE, CacheP_TYPE_ALL);
    /* Read 8 chars */
    gNumBytesRead = 0U;
    transRx.buf   = &gUartReceiveBuffer[0U];
    transRx.count = 5;
    transferOK = UART_read(gUartHandle[CONFIG_UART_CONSOLE], &transRx);
    APP_UART_ASSERT_ON_FAILURE(transferOK, transRx);
    SemaphoreP_pend(&gUartReadDoneSem, SystemP_NO_WAIT);

    /* Echo chars entered */

    while(1)
    {
        if(rxcomplete==1)
        {
            gNumBytesWritten = 0U;
            trans.buf   = &gUartReceiveBuffer[0U];
            trans.count = transRx.count;
            transferOK = UART_write(gUartHandle[CONFIG_UART_CONSOLE], &trans);
            APP_UART_ASSERT_ON_FAILURE(transferOK, trans);
            SemaphoreP_pend(&gUartWriteDoneSem, SystemP_NO_WAIT);
            rxcomplete=0;

            gNumBytesRead = 0U;
            transRx.buf   = &gUartReceiveBuffer[0U];
            transRx.count = 5;
            transferOK = UART_read(gUartHandle[CONFIG_UART_CONSOLE], &transRx);
            APP_UART_ASSERT_ON_FAILURE(transferOK, transRx);
            SemaphoreP_pend(&gUartReadDoneSem, SystemP_NO_WAIT);
        }
    }
    /* Send exit string */

    return;
}
void RxCallback(UART_Handle handle, UART_Transaction *transaction)
{
    DebugP_assertNoLog(UART_TRANSFER_STATUS_SUCCESS == transaction->status);
    gNumBytesRead = transaction->count;
    SemaphoreP_post(&gUartReadDoneSem);
    rxcomplete=1;
//        (void)RTI_counterEnable(CONFIG_RTI0_BASE_ADDR, RTI_TMR_CNT_BLK_INDEX_0);


}

void TxCallBack(UART_Handle handle, UART_Transaction *transaction)
{
    DebugP_assertNoLog(UART_TRANSFER_STATUS_SUCCESS == transaction->status);
       gNumBytesWritten = transaction->count;
       SemaphoreP_post(&gUartWriteDoneSem);
}
uint8_t timer1ms;
void TimerCallback()
{
    timer1ms++;
//    rxcomplete = 1;
    (void)RTI_counterDisable(CONFIG_RTI0_BASE_ADDR, RTI_TMR_CNT_BLK_INDEX_0);

}

Please suggest how to handle Uart Errors also (Frame error and over run error)

Hi Rohal,

One question,

What is the value you have configured in your UART module in example.syscfg? By default, the trigger level is set to 8

This means that as soon as Rx FIFO has 8Bytes, it will trigger an interrupt.

Regards,
Shaunak