Problem configuring USART transmitter, not showing data on hercules

[Edizzon]

I am a beginner, I am programming a stm32F411RE with Keil 5, when I was configuring the USART transmitter, Hercules and Arduino did not show any data, I reviewed several videos and I have the same problem, it has been several days. Thanks community.

#include <stm32f4xx.h>

void delay(int tiempo);
void USART2_Config();
void USART2_SendChar(uint8_t c);

int main(){
	USART2_Config();
	
	while(1){
	USART2_SendChar('A');
	delay(1000);
	}
	
}

void USART2_Config(){
	
	RCC->APB1ENR |= (1<<17); //Enable USART CLK
	RCC->AHB1ENR |= (1<<0);  //Enable GPIOA CLK
	
	GPIOA->MODER |= (2<<4);  //Alternate Function for Pin PA2 
	GPIOA->MODER |= (2<<6);  //Alternate Function for Pin PA3 
	
	GPIOA->OSPEEDR|=(3>>4)|(3>>6); // High Speed for PIN PA2 and PA3
	
	GPIOA->AFR[0] = (7<<8); // AF7 Alternate function USART2 at Pin PA2
	GPIOA->AFR[0] = (7<<12); // AF7 Alternate function USART2 at Pin PA3
	
	USART2->CR1 |= 0x00;   //  clear all
	USART2->CR1 |= (1<<13);//  USART ENABLE
	
	USART2->CR1 |= ~(0>>12); //M = 0; 8 bits word length
	
	USART2->BRR |= (8<<0)| (325<<4);  //  baud rate register 9600   
	USART2->CR1 |= (1<<2); //  RX
	USART2->CR1 |= (1<<3); //  TX
}


void USART2_SendChar(uint8_t c){
	USART2 -> DR = c;
	while(!(USART2->SR & (1<<6)));
}


void delay(int tiempo){
	int i;
	for(;tiempo>0;tiempo--){
		for(i=0;i<=3195;i++);
	}
}

[Andrew Neil]

---

@Edizzon wrote:

Hercules and Arduino

---

How are the "Hercules and Arduino" connected to the stm32 ?

Have you used an oscilloscope to see if there is any activity at all at the TX pin?

Is the stm32F411RE on a standard ST board, or your custom design?

[TDK]

> GPIOA->OSPEEDR|=(3>>4)|(3>>6); // High Speed for PIN PA2 and PA3

This does nothing. 3 >> 4 and 3 >> 6 are both 0. You probably want << and not >>.

> USART2->CR1 |= 0x00; // clear all

This does not clear anything.

> USART2->BRR |= (8<<0)| (325<<4); // baud rate register 9600 

Seems off, if your system clock is 16 MHz. Should be 26667 if my math is correct.

Software-based delay loop is unpredictable and can be optimized out entirely. Marking the counter as "volatile int i" will help a bit.

[SofLit · Accepted solution]

Hello,

As you're a beginner, start by using HAL provided in STM32CubeF4 and inspire from this example https://github.com/STMicroelectronics/STM32CubeF4/tree/master/Projects/STM32F411RE-Nucleo/Examples/UART/UART_Printf

Then if all are good, switch to the optimization approach by directly access to the registers as you're doing as it could be a tricky approach from the beginning (forget to set a bit, wrong shift etc ..).