Thanks Andy, I only call from ISR during testing because it can provide delay time between sending.

Yes, after that I will put the code in main():

void main (void)
{
	Mcu_init();
	lcd_init();	
	serial_init();
//.....

while (1) 	
{         
   IOs();
   WDT_reset();

//   printf code here....

   WDT_reset();
}
 

Is that OK, Andy?

And also as my previous post, why I can not call printf in any where rather than in main() or interrupt ???

Thanks,