ST-LINK SWO printf输出

勾选使用keil 微库，然后添加以下代码

#include “stdio.h”
#define ITM_Port8(n) (((volatile unsigned char )(0xE0000000+4n)))
#define ITM_Port16(n) (((volatile unsigned short*)(0xE0000000+4n)))
#define ITM_Port32(n) (((volatile unsigned long )(0xE0000000+4n)))

#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);
}