printf bringt HC12 zum Absturz

#include <hc12.h>

#include <912b32.h>

#include <stdio.h>

int Zaehler=0;

int i=1234;

#pragma interrupt_handler Zeitbasis

void Zeitbasis(void)

{

 TC0 = TCNT + 65530;

 Zaehler++;

 putchar('2');

 TFLG1 = 0x01;

}

void main(void)

{

 *((unsigned char *)0x0be8) = 0x06;    

 *((void (**)(void))0x0be9) = Zeitbasis; 

  TSCR=0x80;                               

  TMSK2=0x05;                                        

  TIOS=0x01;               

  TMSK1=0x01;                

  TFLG1=0xFF;

  INTR_ON();

  while (1)

  {  

  if (Zaehler == 50)

     {  

      printf("Wert: %d \r",i);

    Zaehler = 0;

   }   

  }  

}