How to use printf with System Workbench for STM32

step 1  right click  --> properties

 step 2 C/C++ build  --> Setting

 step 3 Select Miscellaneous

 step 4  Edit Linker Flags to    -specs=nosys.specs -specs=rdimon.specs -lc -lrdimon

step 5 go to Debug  and select Debug Config

step 6  ****If you  never have been debugging you should double click at Ar6 debugging icon  for create debugging  for your project  *****

step 7 Select run at your debugging project  and add massage to  Initialization Command
                                                                      monitor reset halt

step 8 Add this Function to you code  for initial  debugging by printf

/*
 *  initial_this function for use printf in debug
 */
#define DEBUG
extern void initialise_monitor_handles(void);
__weak void initial_printf()
{
/*
*  properties ->C/C++ Build  -> Setting ->  Miscellaneous
*   and input this text   -specs=nosys.specs -specs=rdimon.specs -lc -lrdimon to Linker flags
*/
#ifdef DEBUG
initialise_monitor_handles(); 
printf("start Debug Mode \n");
#endif

}
int main(void)
{
   initial_printf();
  while(1)
  {  printf("Hello debug")  }

}

result  any massage is you want to print  will show at Console 

Enjoy with Debugging by printf