【记录】STM32 printf函数实现方法

概要

实现

#include "usart.h"

#pragma import(__use_no_semihosting)

struct __FILE
{
int handle;
/* Whatever you require here. If the only file you are using is */
/* standard output using printf() for debugging, no file handling */
/* is required. */
};
/* FILE is typedef’ d in stdio.h. */
FILE __stdout;
_sys_exit(int x)
{
x = x;
}

//redefine fputc using USART1
int fputc(int ch, FILE *f)
{
//status register, [6]transmission complete
while((USART1->SR & 0x40) == 0);
USART1->DR = (u8)ch;
return ch;
}

void uart_init(u32 pclk2, u32 bound)
{
//initialize usart1
}

参考