UART Receive code is not working.

[Siva Ram]

I am using STM32F103C8 MCU and Trying to communicate with Quectel EC200U-CN 4G module and i am not getting data through UART2 Receive pin.

Please go through my code and suggest me

void USART2_IRQHandler(void){
	if ((USART2->SR & USART_SR_RXNE) != RESET){
		GSM_buf[GSM_indx] = USART2->DR;
		GSM_indx++;
		while(!(USART2->SR & USART_SR_TC));
	}
	if(GSM_indx >= (BUF_SIZE-1))
		GSM_indx = 0;
}

[Javier1]

>> go through my code

Thats the equivalent to going to your baker and demanding free bread.

did you checked uart pins TX and RX are properly swapped with your quectel module?

[Siva Ram]

All connections are fine, please check below function. will it works?

1. void USART2_IRQHandler(void){
2. if ((USART2->SR & USART_SR_RXNE) != RESET){
3. GSM_buf[GSM_indx] = USART2->DR;
4. GSM_indx++;
5. while(!(USART2->SR & USART_SR_TC));
6. }
7. if(GSM_indx >= (BUF_SIZE-1))
8. GSM_indx = 0;
9. }

Thanks for reply Javier.

[gbm · Accepted solution]

No. You shouldn't wait for TC flag in the ISR. It has nothing to do with UART reception.

And this:

for(int i = 0;i<500000;i++);

may be optimized to nothing, so no delay will be provided.

[Siva Ram]

Thank you gbm

[SandeepK]

Could you send me the overall code for sending and receiving the msg from EC200U-cn I have tried with At commands sending through the UART,which one is the crt way?