Long Timer

[Tissy]

Right cracked it, thanks very much for everones help.

Regards,

Steve

[Tissy]

Ok, i got greedy. I have now added hours to the routine.

However, i have done a test, setting the delay at 8hrs 45min 32 seconds
and it triggered at 8hrs 44min 06 seconds.

Two things really, is the the type of result expected. I know its a small margin of error, but i thought 1000ms is a 1000ms. Alternatively is there an error in the code that someone can see?

    If HoursDelay > 0 then
    For Hours = 1 to HoursDelay
    For Minutes = 1 to 60
    For Seconds = 1 to 60
    If SW2 = 1 Then Goto main
    Toggle Red ' flashing light for reference
    Pause(1000)
    Next Seconds 
    Next Minutes
    Next Hours
    EndIF    

    If MinutesDelay > 0 then
    For Minutes = 1 to Minutesdelay
    For Seconds = 1 to 60
    If SW2 = 1 Then Goto main
    Toggle Red ' flashing light for reference
    Pause(1000)
    Next Seconds 
    Next Minutes
    EndIF

    If SecondsDelay > 0 then
    For Seconds = 1 to SecondsDelay
    If SW2 = 1 Then goto main
    Toggle Red ' flashing light for reference
    pause(1000)
    Next Seconds
    EndIF

I thought it would be a little more accurate than that. If i set the delay at 32seconds then it triggers at 32seconds.

There are only so many lengthy test you can do, waiting 8hrs for an event to trigger is a long time !!

Cheers,

[Tissy]

Can anyone answer the above ?

[Ingvar]

What oscillator are you using?

Your error is 0.27%, not very good if you're using a crystal. Quite possible if using a resonator, very good if you're using internal oscillator.

You should also ask yourself if minute or so matters over 8 hours.

/Ingvar

[Tissy]

Cheers for the reply.

I am using a 20MHz resonator. So you reckon if i put in a Crystal instead, that should improve matters?

I know what your saying about a minute error over 8 hours, but i just wanted it as accurate as possible. When its timing seconds only, thats fine, the error just creeps in over longer periods.

I will get myself a 20MHz crystal and see if this changes things.

I also really just wanted to make sure my code looks OK, there's only so many times you can tolerate waiting a long period to check for accuracy.

Regards,

Steve

[Ingvar]

Well ...... it's always a good start to KNOW that your oscillator is reasonable accurate. You will definatley get a more accurate source using a crystal. If it makes your timing worse, atleast you know it's in the software. Personally, i would have made this kind of application with a timer and interrupt. Not that it's absolutley necessary, i just find timers useful for timingpurposes.