UART transmitter transmits wrong ascii value to my pc.

[khairul_bashar]

UART transmitter transmits wrong ascii value to my pc.

what is the problem in my code..??

I put a charecter in Data Register, but serial terminal show another ascii code.

My IDE is KeiluVision5. the code is in below.....

 

 

#include<stdint.h>

#include<stdio.h>

#include<stm32f446xx.h>

 

#define GPIOAEN (1U<<0)

#define UART2EN (1U<<17)

 

#define CR1_TE (1U<<3)

#define CR1_UE (1U<<13)

#define SR_TXE (1U<<7)

 

#define SYS_FREQ 45000000

#define APB1_CLK SYS_FREQ

 

#define UART_BAUDRATE 115200

 

void uart2_tx_init(void);

void uart2_write(uint8_t ch);

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);

 

 

 

 

int main(void){

 

uart2_tx_init();

 

while(1){

 

uart2_write('z');

for(int i=0;i<1000000;i++){}

}

 

}

 

 

 

 

 

void uart2_write(uint8_t ch){

 

//********************************************************

// make sure tranmit data register is empty

while(!(USART2->SR & SR_TXE)){}

 

//write to the transmit data register

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

 

 

}

 

 

void uart2_tx_init(void){

 

//***************configure GPIO PIN****************

//enabling clock access on GPIOA

RCC->AHB1ENR |= GPIOAEN;

 

//set PA2 as Alternate function mode

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

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

 

// set alternate function type AF07

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

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

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

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

 

 

//***************configure UART****************

//enable clock access to usart2

RCC->APB1ENR |= UART2EN;

 

//configure baudrate

uart_set_baudrate(USART2, APB1_CLK, UART_BAUDRATE);

 

//configure data transfer direction

USART2->CR1 |=CR1_TE;

 

//Enable uart module

USART2->CR1 |=CR1_UE;

 

}

 

 

 

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){

 

//uint16_t abc = ((PeriphClk + (BaudRate/2))/ BaudRate);

 

//printf("abc");

 

return (uint16_t)((PeriphClk + (BaudRate/2))/ BaudRate);

 

 

}

 

 

 

 

[KnarfB]

The most common reasons are a baudrate mismatch between transmitter and receiver or some different code page/char translation done by "intelligent" terminal progs on the receiver side. Check the signals on the wire using a scope or a cheap logic analyzer.

hth

KnarfB

[khairul_bashar]

Thank you for your suggestion.