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);
}
