WHYTHO

uint8_t interrupt_count1 = 0;
uint8_t interrupt_count2 = 0;
uint8_t tacno1 = 0;
uint8_t tacno2 = 0;
void process_tim1_update_interrupt()
{
 ...
 if(++interrupt_count1 == 250 || tacno1 == 1)
 {
   tacno1 = 1;
   if(++interrupt_count2 == 250)
   {
	tacno1 = 0;
    interrupt_count1 = 0;
    interrupt_count2 = 0;
   ...
   }
 }
}