Precise timing

W

wob_b

New Member
I am trying to design a program to display the amount of time i have been on the phone for, as i get free phone calls or an hour and always seem to forget and just go over (lol). i found a simple circuit to put an LED on when the phone was off the hook, and was going to use this as an input. Maybe add some kinda of hold as well for fun. Then just pulse with a pin to attached to a decade counter, to a seven segment display or possibly LCD screen - if i can get my head round LCDs.

However, i know that the programs take time to run. How much will this effect the precision of my circuit? how inaccurate will it make it and is there a way of i compensate?
 
Peter M

Peter M

Senior Member
Papaof2, Ive tried numerous times (today and at other times) to get onto your site... have had nil success??? any clues
 
hippy

hippy

Technical Support
Staff member
Papaof2's site seems to be working okay now, at least for me.

It is possible to get a PICAXE keeping track of time as accurately as a battery clock would, even an 08M using just a watch crystal.
 
M

moxhamj

New Member
The DS1307 clock chip could be used - you could check the time and get the number of seconds/minutes etc. You probably would need an LCD display, and expect to spend a few days on this sort of project. I built a pump controller http://drvernacula.topcities.com/lcd_clock_for_controlling_pumps_.htm which uses the DS1307 clock chip and a display, though it uses and 18X and it ran out of output pins and so needed an HC595, and if I built it again I would use a 28X and the LCD display driver code would end up simpler.

Mind you, if the rest of the code is simple, pause 1000 gives a delay of 1 second and in a loop of 60 it still ticks once a minute as accurately as my watch.

Do you have a strong preference for LCD or LED displays?
 
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