tica, simsun, u5b8bu4f53">STM32  printf问题
怎么老是出现idenfier "FILE is Undefined",问题出在哪啊？望指教，谢谢！
我程序代码配置如下：
#include "stm32f10x.h"
#include "stm32_eval.h"
#include <stdio.h>

#ifdef __GNUC__
  /* With GCC/RAISONANCE, small printf (option LD Linker->Libraries->Small printf
     set to 'Yes') calls __io_putchar() */
  #define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
  #define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif /* __GNUC__ */

int main(void)
{
    SystemInit();
    /* Enable GPIOA and USART1 clocks */
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_USART1, ENABLE);
   
    USART1_GPIO_Configuration();
    USART1_Configuration();
        
    printf("The is a example!" );
   
}


/*********************************配置USART1的GPIO口*************************************/
void USART1_GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
// Configure USART1_Tx as alternate function push-pull
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOA, &GPIO_InitStructure);

// Configure USART1_Rx as input floating
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA, &GPIO_InitStructure);
}
/************************************配置串口1参数***********************************/

void USART1_Configuration(void)
{

   USART_InitTypeDef USART_InitStructure;

   USART_InitStructure.USART_BaudRate =115200;
   USART_InitStructure.USART_WordLength = USART_WordLength_8b;
   USART_InitStructure.USART_StopBits = USART_StopBits_1;
   USART_InitStructure.USART_Parity = USART_Parity_No ;
   USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
   USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;

   USART_Init(USART1, &USART_InitStructure);

   USART_Cmd(USART1, ENABLE);
}


PUTCHAR_PROTOTYPE
{
  /* Place your implementation of fputc here */
  /* e.g. write a character to the USART */
  USART_SendData(USART1, (uint8_t) ch);

  /* Loop until the end of transmission */
  while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET)
  {}

  return ch;
}
========================================

因printf()之类的函数，使用了半主机模式。使用标准库会导致程序无法运行,以下是解决方法:

方法1.使用微库,因为使用微库的话,不会使用半主机模式.

方法2.仍然使用标准库,在主程序添加下面代码:

#pragma import(__use_no_semihosting)
_sys_exit(int x)
{
x = x;
}
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;

这个方法确实解决问题。

首先要加上这句：#include <stdio.h>
然后加入以下代码：
///////使用标准printf的串口字节发送重定义///////////
//第一步：
#ifdef __GNUC__
  /* With GCC/RAISONANCE, small printf (option LD Linker->Libraries->Small printf
     set to 'Yes') calls __io_putchar() */
  #define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
  #define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif /* __GNUC__ */
//第二步：
#pragma import(__use_no_semihosting)
_sys_exit(int x)
{
x = x;
}
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;
//第三步：
//默认使用COM1
/**
  * @brief  Retargets the C library printf function to the USART.
  * @param  None
  * @retval None
  */
PUTCHAR_PROTOTYPE
{
          /* Place your implementation of fputc here */
          /* e.g. write a character to the USART */
  
          /* Loop until the end of transmission */
          while (USART_GetFlagStatus(USART_COM1, USART_FLAG_TC) == RESET)
          {}
        USART_SendData(USART_COM1, (uint8_t) ch);
          return ch;
}
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