Posted on December 15, 2015 at 16:22 Hello there,
I am experiencing a weird behaviour in my application. I am using HAL library. I am using STM32F407 and usart2 to send and receive using DMA in half-duplex mode.
Everything is working fine, until I decide to send a message with different lenght and wait for an answer with different length. What I mean is, if i send and receive same length frames it is working. If I change it, it skips the first reception packet and after that everything is shifted somehow in the reception buffer.
This is my procedure. First of I send:
HAL_StatusTypeDef rs485_sendData(uint8_t* buffer, size_t len)
{
HAL_StatusTypeDef ret = HAL_OK;
ret |= HAL_HalfDuplex_EnableTransmitter(p_rs485_usartHandle);
rs485_SetTransmissionMode();
while (HAL_UART_GetState(p_rs485_usartHandle) != HAL_UART_STATE_READY);
ret |= HAL_UART_Transmit_DMA(p_rs485_usartHandle, buffer, len);
return ret;
}
rs485_SetTransmissionMode(); sets DE pin High because this is rs4
After I send i get Tx interrupt:
void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart)
{
assert_param(huart);
if (huart == p_rs485_usartHandle)
{
assert_param(p_rs485_msgInfo);
rs485_SetReceptionMode();
HAL_HalfDuplex_EnableReceiver(p_rs485_usartHandle);
HAL_UART_Receive_DMA(p_rs485_usartHandle, rs485_rxBuffer,
p_rs485_msgInfo->rxDataLen + RS485_PAYLOADS_SIZE);
}
}
HAL_UART_Receive_DMA I specify for how many bytes I am waiting. WHen they come i get rx interrupt:
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
assert_param(huart);
if (huart == p_rs485_usartHandle)
{
// -1 because crc byte is not taken
uint8_t crc = rs485_getCRC(rs485_rxBuffer, p_rs485_msgInfo->rxDataLen + RS485_PAYLOADS_SIZE - 1);
// check CRC (-1 because its index)
if (rs485_rxBuffer[p_rs485_msgInfo->rxDataLen + RS485_PAYLOADS_SIZE - 1] == crc)
{
// CRC OK
Led_Toggle(2);
if (osOK != osMessagePut(msgQId_rs485Frame, (uint32_t)rs485_rxBuffer, 0))
log_PushLine(e_logLevel_Critical, ''Unable to put rs485 rx message in the queue'');
}
else
{
log_PushLine(e_logLevel_Warning, ''Received command %u with bad crc!'', rs485_rxBuffer[1]);
}
}
}
And this works quite fine if from the begining of code I send the same message all the time. But lets say after a while i start to send a bit different message, that also receives answer with different amount of bytes. I specify that and while debuging I see that for the first different message I send I dont get any answer at all and on my rs485 sniffer i see that the answer is sent. I just dont receive it in code and I have no idea why. Im on this for all day now. I tried doing DMA init before each send but that didnt change anything...
Is there something I am missing in the confifuration? I would really apreciate all help!
