PIC Microcontroller using C - c

Question

I am trying to get this code to work in MM:SS:FFFFFF, where MM is minutes, SS seconds and FFFFFF micro seconds, but my minutes are bot working properly. Instead of getting anything like 01:05:873098 I get 00:65_873098. Thanks for any tip.
#include <prototype.h>
int16 overflow_count;
#int_timer1
void timer1_isr(){
overflow_count++;
}
void main(){
int32 time;
setup_timer_1(T1_INTERNAL | T1_DIV_BY_1);
enable_interrupts(int_timer1);
while(TRUE){
enable_interrupts(global);
while(input(PUSH_BUTTON)); //Wait for press
set_timer1(0);
overflow_count=0;
while(!input(PUSH_BUTTON)); //WAIT FOR RELEASE
disable_interrupts(global);
time=get_timer1();
time=time+((int32)overflow_count<<16);
time-=15; //substract overhead
printf("Time is %02lu:%02lu.%06lu minutes.\r\n",
time/1000000000, (time/6000000), (time/5)%1000000);
}
}

Answer 1

I would suggest that you introduce some intermediate variables like "ticks", "microsecs", "secs", and "mins". Do the calculations step by step, from smallest unit to largest, remembering to subtract off each part before converting the next larger part. Make sure the units work out at each step of the conversion (e.g. don't add or subtract values that have different units). Think about how you'd do it with pencil and paper: probably not the way you've written it! When you break it down like that, it will be easier to get the logic correct.

Answer 2

you aren't ever subtracting out the whole parts
if time is time in micro's... something like:
time = time % (24 * 60 * 60 * 1000); //mod out any extra days
int hours = time / (60 * 60 * 1000);
time = time % (60 * 60 * 1000); // or time -= hours*(60 * 60 * 1000)
int min = time / (60 * 1000);
time = time % (60 * 1000); // or time-= min*(60*1000)
...