I am using an STM32L476RG , I worte a code for UART communication. But am not able to get the output.

[Charlie4918]

#include "stm32l4xx.h"

#include <stdint.h>

#define SYS_FREQ 16000000

#define APB1_CLK SYS_FREQ

#define UART_BaudRate 115200

#define GPIOAEN (1U<<0)

#define UART2EN (1U<<17)

#define CR1_TE (1U<<3)

#define CR1_UE (1U<<0)

#define ISR_TXE (1U<<7)

static void uart_setBaudRate (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 GPIO pin**************************/

/*Enable clock access to gpioA*/

RCC->AHB2ENR |=GPIOAEN;

/*Set PA2 mode to alternate function type*/

GPIOA->MODER &=~(1U<<4);

GPIOA->MODER |=(1U<<5);

/*Set PA2 alternate mode to uartTX AFO7*/

GPIOA->AFR[0] |=(1U<<8);

GPIOA->AFR[0] |=(1U<<9);

GPIOA->AFR[0] |=(1U<<10);

GPIOA->AFR[0] &=~(1U<<11);

/************Configure UART mode**************************/

/*Enable Clock acess ti uart2*/

RCC->APB1ENR1 |=UART2EN;

/*Configure Baudrate*/

uart_setBaudRate(USART2,APB1_CLK,UART_BaudRate);

/*Configure the transfer direction*/

USART2->CR1 = CR1_TE;

/*Enable usart module*/

USART2->CR1 |= CR1_UE;

}

void uart2_write(int ch){

/*Make sure transmit data register is empty*/

while(!(USART2->ISR & ISR_TXE)){}

/*Write to transmit data register*/

USART2->TDR = (ch & 0xFF);

}

static void uart_setBaudRate (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);

}

[Paul1]

a) Use STM32CubeMX to generate initialization code for your STM32 pinout, and check if you missed anything.

b) Look at the tutorials for sample UART code.

c) Attached project in C++ using STM32CubeMX has some useful startup code: STM32L476RG-Nucleo_TestsPR06.zip

*I suggest C++ for the enhanced compile time checking, even if everything is just C Code.

d) Did you make your own PCB or are you using a standard board like a Nucleo? What is the STM32 pinout and schematic?

*When posting code use the </> in toolbar so code keeps formatting and is easier to read.

Paul

[SVemp.2]

@Charlie4918​ : Can you please tell me why the equation return ((PeriphClk +(BaudRate/2U))/BaudRate); was used?