Minute second and millisecond timer on an LCD

Forum 2005-2010 (read only) Hardware Interfacing
#1

Having some trouble with programing an accurate min, sec, millisec, timer. I can make only one accurate at a time. Any ideas?

#2

For a timer function:

For the start time, read millis() and store its value in a variable named time0

Then, to display elapsed time for the count loop set up the cursor position and call the following function as often as you want to:

  print_time(millis() - time0);

Here's a print routine that can convert a long int, corresponding to milliseconds, to days, hours, minutes, seconds and milliseconds and print to the LCD.

// argument is time in milliseconds
void print_time(unsigned long t_milli)
{
    char buffer[20];
    int days, hours, mins, secs;
    int fractime;
    unsigned long inttime;

    inttime  = t_milli / 1000;
    fractime = t_milli % 1000;
    // inttime is the total number of number of seconds
    // fractimeis the number of thousandths of a second

    // number of days is total number of seconds divided by 24 divided by 3600
    days     = inttime / (24*3600);
    inttime  = inttime % (24*3600);

    // Now, inttime is the remainder after subtracting the number of seconds
    // in the number of days
    hours    = inttime / 3600;
    inttime  = inttime % 3600;

    // Now, inttime is the remainder after subtracting the number of seconds
    // in the number of days and hours
    mins     = inttime / 60;
    inttime  = inttime % 60;

    // Now inttime is the number of seconds left after subtracting the number
    // in the number of days, hours and minutes. In other words, it is the
    // number of seconds.
    secs = inttime;

    // Don't bother to print days
    sprintf(buffer, "%02d:%02d:%02d.%03d", hours, mins, secs, fractime);
    lcd.print(buffer);
}

Regards,

Dave

#3