在工程里面添加下列代码：

#include 
    
     #define ITM_Port8(n)    (*((volatile unsigned char *)(0xE0000000+4*n)))#define ITM_Port16(n)   (*((volatile unsigned short*)(0xE0000000+4*n)))#define ITM_Port32(n)   (*((volatile unsigned long *)(0xE0000000+4*n)))#define DEMCR           (*((volatile unsigned long *)(0xE000EDFC)))#define TRCENA          0x01000000//半主机模式必须定义这个struct __FILE{    int handle;};FILE __stdout;FILE __stdin;int fputc(int ch, FILE *f){    if (DEMCR & TRCENA)    {        while (ITM_Port32(0) == 0);        ITM_Port8(0) = ch;    }    return(ch);}
    

点击JLink的调试设置对话框，Trace页面，如下图设置即可：

原始文章：