UART LOOP using registers

How does it synchronize or move data between the buffers?

The TX is just going to saturate in a continuous loop, sending as fast as possible.

The RX is going to pace at the rate data comes it. He it will stall until it hits TC

Not sure I'm at all interested in decoding register bits on uncommented code, hard to determine intent.

Shouldn't have massive delays in IRQ handlers.

You need to think harder about managing, buffering and sequencing. Best to understand the mechanics rather than stab at the problem and hope.

#include <stm32f7xx_ll_usart.h>
 
void uart_loop(USART_TypeDef *UW, USART_TypeDef *UT)
{
 for(;;)
 {
 if (LL_USART_IsActiveFlag_RXNE(UW)) {
	 if (LL_USART_IsActiveFlag_TXE(UT)) {
	 LL_USART_TransmitData8(UT, LL_USART_ReceiveData8(UW));
	 }
 }
 
 if (LL_USART_IsActiveFlag_RXNE(UT)) {
	 if (LL_USART_IsActiveFlag_TXE(UW)) {
	 // Stop on ^C
	 uint8_t ch = LL_USART_ReceiveData8(UT);
	 if (ch == 3) {
		 break;
	 }
	 LL_USART_TransmitData8(UW, ch);
	 }
 }
 }
}

> USART2->CR1 |= (1<<3);

As Tesla said, this is not very readable. Better use the pre-defined register bit definitions from the specific STM's header file.

Post edited to adhere community guidelines.

Post deleted to adhere community guidelines.

@LimoGr​ post your code so we can dissect the issue.