5 minutes timing without RTC

[soulraven]

Hi, is any solution for counting time, like 5 minutes without using RTC? and is it possible in this time to make another application to run?
I have this project
Ibutton identifier for car security.
IF Ibutton is connected confirm the TAG with beep sound and activate 1 PIN with logic state 1, after that if the motor is started keep the pin state, is not after 5 minutes change the pin state to 0. When the motor is stop change the pin state to 0.

[SherpaDoug]

5 minutes is 300 seconds. If you have a interrupt or polling loop every 2 seconds, when it counts 150 loops then 5 minutes has passed. Scale the numbers for whatever interrupt or loop you have.
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[soulraven]

and how i do that? i am not verry good in C. Is need to use intrerupts?

[Geps]

Have a read through these (2nd part can be found via Google)
http://ww1.microchip.com/downloads/en/DeviceDoc/51682A.pdf

And then read through the help sections and examples in CCS.

That should give you a good idea of how to approach it.

[SherpaDoug]

[John P]

No, you don't need to use interrupts, especially if the timer is set to give long intervals. Just have your main() routine poll the interrupt flag that's controlled by the timer; if found to be set, clear it and increment a counter, and when the counter reaches the appropriate level (based on how many timer intervals make up your 5-minute period) do whatever you do when the time runs out.

Note that the interrupt flag gets set regardless of whether the processor is programmed to respond to it, and you can just go and look at it whenever you want. You have to remember to clear it if it's set, though.

The one thing to beware of is that you mustn't send the processor off into some very long routine that will cause testing of the flag to be missed. If this happens, your 5 minutes will be stretched.

[soulraven]

pls, do you have a example source code? something.....I am not very good in C programing...

[PCM programmer]

Look at this CCS example file. It uses Timer1 interrupts to increment
a global 'seconds' variable. You can modify this to do what you need.

[John P]

The example PCM programmer listed was based on having the CCS material on your computer in the expected place, but there's also this on the CCS website:

http://www.ccsinfo.com/content.php?page=compexamples#seconds

It actually does use interrupts, which isn't the only way to do the job but it's the way most people would do it.

[soulraven]

I continue the question...
I am not very good in C and programing. I need that the timer will be activated on some action.
The project is like that:

I use 1wire ibutton.

When ibutton is connected, if is the right one, 1 pin from PIC is HIGH for 5 minutes. If in this interval another pin is not changed from low to high the first pin goes to LOW. If is connected the first pin stay in HIGH until the second PIN goes to LOW. Then the circle repeats.
ibutton, 1 pin to HIGH for 5 minutes...

Sorry for my bad english

[bkamen]

SoulRaven,

You are going to have to do some homework yourself.

People have pointed you to working examples and explained how to accomplish your task in several ways.

If you are not good at C, then here's your chance to learn as you'll find no one will want to do your project for you.

But we are all glad to help when you get stuck.

Good Luck!

-Ben
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Dazed and confused? I don't think so. Just "plain lost" will do. :D

[soulraven]

Yes, I know that. The question is, how I enable the timer when I want and when I want.

[bkamen]

[pmuldoon]

Would it be too rude to suggest hiring a programmer?
You don't seem to want to study and learn a bit so that you can ask very specific questions. You just want a solution created for you - that's what programmers do...for $$.

[bkamen]