Right-click on the syscalls.c file and select Properties. Under C/C++ Build > Settings, check Exclude resource from build.

in main.c: <br/>
```c
#include <stdio.h>
#include "retarget.h"
char buf[100];
RetargetInit(&huart1);
```

Example:<br/>
```c
printf("\r\nYour name: ");
scanf("%s", buf);
printf("\r\nHello, %s!\r\n", buf);

```