UART transmission Issue in stm32g4

Are you sure the data is received and in-sync with the correct CRC? Because if not, this code won't send anything back.

Output diagnostics to SWV or another UART for review.

Hi @Tesla DeLorean ,

I can able to see the transmitted data from STM32G4 to other mcu in dock light that means CRC is in sync. The problem is some times its not transmitting, Yes, may be that time CRC not in sync that's why I can able to receive but I can't able to transmit.
How to solve the issue like its happening sometimes not every time.
Coming to UART-its same with other uart also and  I am using UART not USART is that make any difference.

Thanks 

Tx_data is correct only I just removed because it is just assigning the values.
below I mentioned that part

ocpp_txdata[0] = 0x23;
	 ocpp_txdata[1] = 0x12;
	 ocpp_txdata[2] = 0x12;
	 ocpp_txdata[3] = 0x02;
	 ocpp_txdata[4] = 0x01;
 ocpp_txdata[5] =0x00;
	 ocpp_txdata[6] =0x01;
 ocpp_txdata[7] 0x02;
	 ocpp_txdata[8] =0x04;
	 ocpp_txdata[9] =0x01;
 ocpp_txdata[10] =0x05;
 ocpp_txdata[11] =0x04;
	 ocpp_txdata[12] =0x02;
	 ocpp_txdata[13] =0x00;
 ocpp_txdata[14] =0x05;
	 ocpp_txdata[15] =0x05;
	 // compute CRC to place into last 2 bytes
	 uint16_t calculatedCRC = HAL_CRC_Calculate(&hcrc,(uint32_t *)&ocpp_txdata, 16);

	 ocpp_txdata[16] = (calculatedCRC >> 8) & 0xFF; //high CRC byte
	 ocpp_txdata[17] = calculatedCRC & 0xFF; //low CRC byte

 ocpp_txdata[18] = 0x04;
HAL_UART_Transmit(&huart5, ocpp_txdata,19, 100);

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 Your receive method is apt to miss characters. 

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Is there any other way please suggest
Thanks

> whenever I restated the system and if I remove the power in those cases initially I can't able to transmit.

What means initially? Will the transmission start working by itself after some time or you have to reset the STM32 several times?

There is whole class of notorious issues with starting the app after power cycle vs. no power cycle, under debugger vs. no debugger - caused often by wrong connection of NRST or BOOT0 pins. And another class of notorious issues caused by bad power.

> Would want to use a HAL_UART_ReceiveIT() cyclically so it catches all inbound data as it arrives.

Sorry but this often is a recipe for failure. Every call to HAL_UART_ReceiveIT enables the RX interrupt and disables it on completion, creating time windows when interrupt is disabled. This is especially harmful with size = 1 and no FIFO,

>A non-HAL implementation is all possible and likely more efficient.

+1

Hi @Pavel A. @Tesla DeLorean ,

I checked UART communication from pollforconversion to interrupt method. but I am facing the issue.The data is transmitting and receiving between stm32g4 and other mcu.Some time I am not receiving the data properly like SOF always 0x22 and EOF 0x04 always. data bytes not coming peroperly as expected so then i can't be tramit and receive the proper data.
below added code

int main(){ 
//all initializations
HAL_UART_RegisterCallback(&huart5,HAL_UART_RX_COMPLETE_CB_ID,HAL_UART_RxCpltCallback);
 HAL_UART_RegisterCallback(&huart5,HAL_UART_TX_COMPLETE_CB_ID,HAL_UART_TxCpltCallback);
 HAL_UART_Receive_IT(&huart5, ocpp_rxdata, 7); /* USER CODE END 2 */
while(1){
 request();
}
}
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {
 if (huart->Instance == huart5.Instance) {
 alldata_received = 1;
}
}
void request()
{
	if (alldata_received) {
 uint16_t calculatedCRC;
	uint16_t receivedCRC;
 if(ocpp_rxdata[0]==0x22)
 { 	
 	 calculatedCRC = HAL_CRC_Calculate(&hcrc,(uint32_t *)&ocpp_rxdata, 4); 	 
 	 receivedCRC=ocpp_rxdata[4]<<8 | ocpp_rxdata[5];
 	 if(calculatedCRC==receivedCRC){
 switch(ocpp_rxdata[2])
 {
 case 0x01:
 //trasmit data ocpp_txdata[0] to ocpp_txdata[18] 
 //ocpp_txdata[16],ocpp_txdata[17] is crc
 HAL_UART_Transmit_IT(&huart5, ocpp_txdata,19);
 break;
 case 0x02:
 //trasmit data ocpp_txdata[0] to ocpp_txdata[13] 
 //ocpp_txdata[11],ocpp_txdata[12] is crc
 HAL_UART_Transmit_IT(&huart5, ocpp_txdata,14);
 break;
 }
 }
 else{
 crc_error();
 }
 }
	alldata_received = 0;
	HAL_UART_Receive_IT(&huart5, ocpp_rxdata, 7);
}
void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart)
{
	memset(ocpp_rxdata, '\0',7); //empty the reception data buffer

}

Sometimes data reception and tramission happening normally only but sometimes I am receiving the in the proper format so receiver data byte are changing so can't able to receive or transmit.
Please suggest .
Thanks