Need help in making USART2 work on STM32F303RE
Hi, I am doing a MOOC for learning STM32 programming, in the UART topic, we are supposed to implement UART. The course follows STM32F4 but I have an STM32F303RE and I tried to adapt it to my board but it is still not showing anything on the serial monitor (I tried CuteCom and Arduino Serial Monitors as I use a Mac). Can you please tell me what is wrong with the code below? I tried to input various values directly into the BRR register as I had doubts about the baud rate formula in the course.
#include <stdio.h>
#include <stdint.h>
#include "stm32f303xe.h"
#define IOPAEN (1U<<17)
#define UART2EN (1U<<17)
#define CR1_TE (1U<<3)
#define CR1_UE (1U<<13)
#define SR_TXE (1U<<7)
#define SYS_FREQ 16000000
#define APB1_CLK SYS_FREQ
#define UART_BAUDRATE 115200
static void uart_set_baudrate(USART_TypeDef *USARTx, uint32_t PeriphClk, uint32_t BaudRate);
static uint16_t compute_uart_bd(uint32_t PeriphClk, uint32_t BaudRate);
void uart2_tx_init(void);
void uart2_write (int ch);
int main (void){
uart2_tx_init();
while(1){
uart2_write('Y');
}
}
void uart2_tx_init(void){
//Configure UART GPIO pin
// Enable clock access to GPIOA
RCC->AHBENR |= IOPAEN;
// Set PA2 to Alternate Function Mode
GPIOA->MODER &= ~(1U<<4);
GPIOA->MODER |= (1U<<5);
// Set PA2 Alternate Function type to UART_TX (AF07)
GPIOA->AFR[0] |= (1U<<8);
GPIOA->AFR[0] |= (1U<<9);
GPIOA->AFR[0] |= (1U<<10);
GPIOA->AFR[0] &= ~(1U<<11);
//Configure UART Module
// Enable clock access to UART2
RCC->APB1ENR |= UART2EN;
// Configure baud rate
uart_set_baudrate(USART2, APB1_CLK, UART_BAUDRATE);
// Configure the transfer direction
USART2->CR1 = CR1_TE;
// Enable UART module
USART2->CR1 |= CR1_UE;
}
void uart2_write (int ch){
//Make sure transmit data register is empty
while (!(USART2->ISR & SR_TXE)){}
//Write to transmit data register
USART2->TDR = (ch & 0xFF);
}
static void uart_set_baudrate(USART_TypeDef *USARTx, uint32_t PeriphClk, uint32_t BaudRate){
USARTx->BRR = compute_uart_bd(PeriphClk,BaudRate);
}
static uint16_t compute_uart_bd(uint32_t PeriphClk, uint32_t BaudRate){
return ((PeriphClk + (BaudRate/2U))/BaudRate);
}