参考资料：http://www.keil.com/support/man/docs/jlink/jlink_trace_itm_viewer.htm
1.Target Options -> Debug -> Settings(JLink) -> Debug里ort选择SW模式
2.在Target Options -> Debug -> Settings(JLink) -> Trace里选择Enable
3.Core freq设为120MHz（以LPC1788为例）
4. 设置ITM Port的值如下所示
5.在工程中添加.c文件如下
#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 you need here */ };
FILE __stdout;
FILE __stdin; int fputc(int ch, FILE *f) {
if (DEMCR & TRCENA) {
while (ITM_Port32() == );
ITM_Port8() = ch;
}
return(ch);
}
6.用Debug模式运行工程，Debug (printf) Viewer中即可以查看printf的输出信息。