vcp 方式:
int fputc(int ch, FILE *f)
{
while(CDC_Transmit_FS((uint8_t*)(&ch),1)!=USBD_OK){}
return ch;
}
uart 方式:
#include "stdio.h"
#ifdef __GNUC__
#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif
PUTCHAR_PROTOTYPE
{
HAL_UART_Transmit(&huart2 , (uint8_t *)&ch, 1, 0xFFFF);
return ch;
}