Elapsed Timer Demo

[hackableFM]

I have given this a good reading over but some of it has gone straight over my head.
I intend to built a control unit based around a 16F877 which will include menu's to control output pins on the PIC, Obviously within the menu there will likely be instructions which will keep the processor busy for a few Ms at a time. My project ideas originally were to include an external clock device such as the DS1307 or the DS1603 to keep track of time whilst the rest of the program (Menu's etc etc) is running and keeping the processor busy.
I was advised on this forum to look at this thread and if this is what I think it is then it will be truly fantastic for my project.

My problem is that when the PIC returns from a menu I want it to display the time on the LCD. Am I right in what I have read in thinking (Besides setting LCD pins & oscillator etc) I can simply include all of the attached files in post number 1 of this thread but modify the 'loop' subroutine within "Test_Elapsed_LCD.pbp" file, to include my menu software?

I understand that this thread creates a time elasped counter and not a clock, but I do have in mind ideas to include buttons with which I can set the hours, minutes & seconds. I will also miss out the displaying of 'Days' when it comes to print on the LCD.

Apologies for what might seem to be a simple question to you guys but I have only been playing for a couple of months with PIC's and I am trying to learn from other people's examples.

Thanks.

hackableFM.

[Darrel Taylor]

I intend to built a control unit based around a 16F877 which will include menu's to control output pins on the PIC, Obviously within the menu there will likely be instructions which will keep the processor busy for a few Ms at a time. My project ideas originally were to include an external clock device such as the DS1307 or the DS1603 to keep track of time whilst the rest of the program (Menu's etc etc) is running and keeping the processor busy.
I was advised on this forum to look at this thread and if this is what I think it is then it will be truly fantastic for my project. ...

It can do the things you are suggesting.

But it's not a replacement for a battery backed-up RTC chip.
Any RESET will lose the accumulated time.

I have used it as a clock running on-chip, but on power-up it reads the time from an RTC. That way it doesn't have to continuously read the time via I2C and it's always available from the internal time clock.
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[hackableFM]

Thank you, This sounds good so I'll have a bit more of a read up on it, I'll try to understand more about how it works before I go building anything.

Battery backed is not an issue, this will be connected to a permanent 12v system within a caravan and therefore never likely to loose the accumulated time.

hackableFM...

[jmgelba]

Hi Darrel,

I'm trying to create a timer - a run time timer that will turn off an output after 30 minutes. Would this code work for such a task?

Thanks

[Darrel Taylor]

Sure, it'll do that really easy.

IF MinutesChanged THEN
    MinutesChanged = 0
    IF Minutes = 30 THEN
        ; turn off whatever it is here
        GOSUB ResetTime
    ENDIF
ENDIF

[jmgelba]

Excellent!

Can it do incremental too? As in can it be started and stopped during the 30 minute period?

Also I need it to run when an output is on, but if the output is only on say 20 minutes then off for say an hour, I dont want it to only run for 10 minutes if the output is turned on again. What this timer is actually doing is stopping high power LED's getting hot due to excessive run time.

[Darrel Taylor]

The Elapsed Timer can be Stopped and Started, like a stopwatch.

 GOSUB StopTimer
 GOSUB ResetTime
 GOSUB StartTimer

You can time things any which way you need to.