can't use HAL_UARTEx_ReceiveToIdle_DMA() with IDLE event

[simon_EQUIUM]

Hello,
I am trying to use the HAL_UARTEx_ReceiveToIdle_DMA function() but the IDLE function don't work.

I call the function here :

/* Extern variables */
extern UART_HandleTypeDef huart4;
extern osEventFlagsId_t comEventHandle;
extern osMessageQueueId_t sensorQueueHandle;
extern osEventFlagsId_t regEventHandle;
extern DMA_HandleTypeDef hdma_uart4_rx;

static void modbus_receive_DMA(void) {
  buf_rec = 0; // reset the counter of received bytes in the buffer

  /* Reset pin for receiving data */
  HAL_GPIO_WritePin(RS485_SIEMENS_RE_GPIO_Port, RS485_SIEMENS_RE_Pin, GPIO_PIN_RESET);

  if (HAL_UARTEx_ReceiveToIdle_DMA(&huart4, nmbs.msg.buf, sizeof(nmbs.msg.buf)) != HAL_OK) {
    log_debug("HAL_UARTEx_ReceiveToIdle_DMA error");
  }

}

void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart) {
  if (huart == &huart4) {
    modbus_receive_DMA();
  }
}

void HAL_UARTEx_RxEventCallback(UART_HandleTypeDef *huart, uint16_t Size) {
  if (huart == &huart4) {
    switch (HAL_UARTEx_GetRxEventType(huart)) {
    case HAL_UART_RXEVENT_IDLE: // when Idle event occurred prior reception has
                                // been completed (nb of received data is lower
                                // than expected one).
      packet_sended = 0;        // clear flag of transmit
      buf_rec = Size;           // set size of received data

      nmbs_error res_poll = nmbs_server_poll(&nmbs);
      if (NMBS_ERROR_NONE != res_poll) {
        // This will probably never happen, since we don't return < 0 in our
        // platform funcs
      }

      // If there was no packet transmission, then we immediately switch to
      // receive mode. Otherwise, this function will trigger an interrupt at the
      // end of DMA packet transmission
      if (!packet_sended)
        modbus_receive_DMA();

      break;
    }
  }
}

I have tryed to replace sizeof(nmbs.msg.buf) by 1 or 2 or 3 and it works but not in IDLE mode. So the function HAL_UARTEx_RxEventCallback works but not in the right way. I have seen on the forum lot of topics with the same problem but I am not able to fix it with my micro..

Do you have any idea ?

[Karl Yamashita]

---

@simon_EQUIUM wrote:

@Karl Yamashita  If I have a problem with in the trame, does the function is called ? For example, the CRC is not complet.

---

Once the parser finds the Line Feed (0x0A), it will queue the packet. You'll have to parse the packet and make sure it's valid. If the packet doesn't have a CRC, then it's a bad packet. So it's up to you on how you want to report the error to the end user.

[simon_EQUIUM]

After your reply I have checked something, and I thing I have something interesting.
When I use Putty and I send only 1 bytes the IDLE work every time.
If I send 2 bytes, the IDLE is never called and its never re-works.
I have to reboot the micro to re-send 1 bytes.
Do you have any idea ?

[Karl Yamashita]

Show what code you have now.

[simon_EQUIUM]

Here the code attached. it is a .C file and the IOC project.

[simon_EQUIUM]

I have tried something, if I use Realterm and I send some ASCII byte, it works like a charm.

BUT If I use KScada Modbus Doctor V2.10 the IDLE doesn't work.

I am wondering if the frame is ok on modbus doctor. But my other question is, if I have a problem with an RS485 frame, how can I prevent my software from being bricked?

[Karl Yamashita]

Use a USB<>Serial adapter and monitor the Rx input of the STM32. Then you can see what the Modbus Doctor does differently than the RealTerm.

A better serial program to use would be Docklight https://docklight.de/

[simon_EQUIUM]

Here some frames KO (modbus) :

Here some frames OK (UART ASCII) :

[Karl Yamashita]

---

I have tryed to replace sizeof(nmbs.msg.buf) by 1 or 2 or 3 and it works but not in IDLE mode.

---

It may have something to do with the amount of bytes you are trying to receive versus the actual amount being received.

Take a look at this project as it might help you set the amount of bytes you want the DMA ro receive in idle mode. https://github.com/karlyamashita/Nucleo-G431RB_Three_UART/wiki

[simon_EQUIUM · Accepted solution]

Thank you Karl,
The DMA doesn't work since the new STM32G473. I have tried with your example but it is not working with the G473 and the NULL byte. I have gave up, and change to normal UART IT. Thank you for your help.