STM32G0学习手册——FreeRTOS中使用printf-stdarg.c

Posted 2021-08-16 SCCELE

1.创建好FreeRTOS代码，在User文件夹中添加printf-stdarg.c。并添加到工程中

2.重定向printf到串口，在usart.c中添加代码

/* USER CODE BEGIN 0 */

#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__ */
///**
//  * @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 EVAL_COM1 and Loop until the end of transmission */
  HAL_UART_Transmit(&huart1, (uint8_t *)&ch, 1, 0xFFFF);
 
  return ch;
}

/* USER CODE END 0 */

3.修改printf-stdarg.c

/*
#define putchar(c) c
*/

static void printchar(char **str, int c)
{
	extern int putchar(int c);       //去掉原本的注释
	
	if (str) {
		**str = (char)c;
		++(*str);
	}
	else
	{ 
		(void)putchar(c);
	}
}

/*修改printf为f_printf。sprintf，snprintf也是一样修改*/
int f_printf(const char *format, ...)
{
	va_list args;

	va_start( args, format );
	return print( 0, format, args );
}

int f_sprintf(char *out, const char *format, ...)
{
	va_list args;

	va_start( args, format );
	return print( &out, format, args );
}


int f_snprintf( char *buf, unsigned int count, const char *format, ... )
{
	va_list args;

	( void ) count;

	va_start( args, format );
	return print( &buf, format, args );
}

 4.修改main.c

#include <stdio.h>
extern int f_printf(const char *format, ...);

/*
*
*/
int main()
{
  /**/
}

static void LED1_Task(void* pvPrameters)
{
	while(1)
	{
		temp_count++;
		HAL_GPIO_TogglePin(GPIOB,GPIO_PIN_1);

        /*串口输出字符*/
		f_printf("LED1_TASK running.");     

		vTaskDelay(1000);
	}
}