1. 因为我的工程用AC6是因为要跑自己的C 和 TensorFlow lite micro. 所以是C，C++混合的工程，但是一直没法打印，所以写一个总结。

基本说明： micro_lib这种情况不要选，因为存在C++文件

第一个坑：

第二个坑：网上大部分教程的重定向printf代码是

__ASM(".global __use_no_semihosting");//??HAL????,?????????bug
//??????????,???????????????,??
int _ttywrch(int ch)    
{ch=ch;return ch;
}//??????????                 
//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 __stdout;     //??_sys_exit()??????????    
void _sys_exit(int x) 
{ x = x; 
} int fputc(int ch, FILE *f){      // usart_data_transmit(USART0, (uint8_t)ch);  //????????// while(RESET == usart_flag_get(USART0, USART_FLAG_TBE));//??????app_uart_put(ch);return ch;
}

某些情况下是可以的（我在52832官方demo这么写是可以的，但是我加了tensorflow lite mirco以后，打印不正常）

换一下代码后正常（串口发送哪个，要换成自己的）：

__ASM(".global __use_no_semihosting");//_swi//__ASM(".global _main_redirection");const char __stdin_name[150];const char __stdout_name[150];const char __stderr_name[150];typedef int FILEHANDLE;typedef unsigned int clock_t;    /* cpu time type */typedef unsigned int time_t;     /* date/time in unix secs past 1-Jan-70 */extern FILE __stdout; //???????,??printf?fopen?fclose????????????????????,???????????????,??????????????void _sys_exit(int status)
{while(1);
}FILEHANDLE _sys_open(const char *name, int openmode)
{return 0;
}int _sys_close(FILEHANDLE fh)
{return 0;}int _sys_write(FILEHANDLE fh, const unsigned char *buf, unsigned len, int mode){return 0;}int _sys_read(FILEHANDLE fh, unsigned char*buf, unsigned len, int mode){return 0;}int _sys_istty(FILEHANDLE fh){return 0;}int _sys_seek(FILEHANDLE fh, long pos){return 0;}int _sys_ensure(FILEHANDLE fh){return 0;}long _sys_flen(FILEHANDLE fh){return 0;}int _sys_tmpnam(char *name, int fileno, unsigned maxlength){return 0;}void _ttywrch(int ch){}time_t time(time_t *t){return 0;}int remove(const char *filename){return 0;}int rename(const char *oldname, const char *newname){return 0;}int system(const char *command){return 0;}char *_sys_command_string(char *cmd, int len){return 0;}clock_t clock(void){return 0;}//???fputc?? int fputc(int ch, FILE *f){app_uart_put((unsigned char)ch);return ch;}

第三个，写自己的打印函数；

#include <stdarg.h>
#include <string.h>#define TX_BUF_LEN  256     /* ???????,???????? */
uint8_t TxBuf[TX_BUF_LEN];  /* ?????                       */
void MyPrintf(const char *__format, ...)
{va_list ap;va_start(ap, __format);/* ??????? */memset(TxBuf, 0x0, TX_BUF_LEN);/* ??????? */vsnprintf((char*)TxBuf, TX_BUF_LEN, (const char *)__format, ap);va_end(ap);int len = strlen((const char*)TxBuf);/* ??????? */for (int i = 0; i < len; i++){app_uart_put( TxBuf[i]);}
}