1，将如下内容拷贝到一个.c文件中放到工程中编译

#include <string.h>
#include <stdio.h>

#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
struct __FILE { int handle; /* Add whatever needed */ };
FILE __stdout;
FILE __stdin;
 
int fputc(int ch, FILE *f) {
    if (DEMCR & TRCENA) {
        while (ITM_Port32(0) == 0);
        ITM_Port8(0) = ch;
    }
    return(ch);
} 

 

2，MDK中设置使用SW模式同时使能Trace输出

 

3，打开Debug Viewer试图即可查看代码中使用 printf() 打印的输出