Stm32_Usart_Rx_Tx.c

#include "stm32f4xx.h"                  // Device header
#include "stdio.h"

void USART2_Init(void);


int main() {
	int n;
	char str[100];
	USART2_Init();
	
	printf("Hello from the other side\r\n");
	fprintf(stdout, "test for stdout\r\n");
	fprintf(stderr, "test for stderr\r\n");
	
	while(1) {
		printf("How old are you? ");
		scanf("%d", &n);
		printf("Your age is : %d\r\n",n);
		printf("Enter your first name : ");
		gets(str);
		printf("I like a your style  :");
		puts(str);
		printf("\r\n");
			
	}
}


void USART2_Init(void){
	RCC->AHB1ENR |= 0x0001;					// Enable GPIOA
	RCC->APB1ENR |= (1<<17);		// Enable USART2: PA2=RX, PA3=TX
	
	GPIOA->AFR[0] |= 0x7700;		// Alternate function for PA2=AF7 and PA3=AF7
	GPIOA->MODER  |= 0x00A0;			// Enable Alternate function for PA2,PA3
	
	USART2->BRR |= 0x0683; 			// 9600 Baudrate: @16Mhz
	USART2->CR1 |= 0x000C;					// Enable RX and TX 
	USART2->CR1 |= 0x2000;			// Enable USART2
}

int USART2_Write(int ch) {
	while(!(USART2->SR & 0x0080));	// Wait for Tx buffer empty
	USART2->DR = (ch & 0xFF);
	return ch;
}

int USART2_Read() {
	while(!(USART2->SR & 0x0020));	// Wait for Rx buffer empty
	return USART2->DR;
}

struct __FILE{int handle;};
FILE __stdin = {0};
FILE __stdout = {1};
FILE __stderr = {2};

int fgetc(FILE *f){
	int c;
	c = USART2_Read();
	if (c == '\r') {
		USART2_Write(c);
		c = '\n';
	}
	USART2_Write(c);
	return c;
}

int fputc(int c, FILE *f) {
	return USART2_Write(c);
}