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Countdown Timer help (pic16f628)

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Newbie level 2
Aug 6, 2009
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pic 16f628 coundown timer

Hi all.....I've built the countdown timer in this site and modified it a little bit to work with 4" and 2.3" displays.

But I want to add 2 new press buttons (while keeping the original buttons in the schematic as they are) one to set the timer to 15 mins and the second to set it to 30 mins then the timer should starts to countdown imediately and when reachs 5 mins activate the relay on RB5 (instead of it being on all time)

I don't know how to modify the code to do that, so your help will be so much appreciated :)

PS. we can use the internal oscillator and use the 2 pins to be I/O for the new buttons

thanks in advance

pic16f incfsz

can anyone even tell me how to start doing this? any help please?

pic16f628 chip used for?


Afraid you are very unlikely for anyone to do that for you.

The chip 16F84 is obselete and the code needs porting onto a more modern chip, which will also need to be a bigger one if you want two extra switches as all 18 pins of that chip are used.

To add switches in to react with the program means you must fully understand all the existing code before you can possibly do that. I doubt anyone would want to spend the time doing that for you.

The best suggestion would be to either design and program your own timer from scratch or sit down and understand all this existing code yourself and then add in the extra switches and functions.

Doing one of these, preferably the first one, will give you a really good beginners project to work at and when complete you will have gained a lot of knowlege about pic programming and hopefully had a rewarding and enjoyable time doing it.

You will doubtless get stuck on some points - but that's where this forum will happily assist.

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