Can this be used with normally closed switches?Originally Posted by aratti
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Can this be used with normally closed switches?
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Yes I made the mistake to write n.o. intending n.c. Sorry for that!
Al.
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What's up with the switches?
Are they what you have on hand and want to use them up?
Are you short of pins on your present project, yet still need to hook up the switches?
Just trying to get a feel for a good solution. The '4067 isn't a bad solution, for an N.O. switch. But I'm thinking, if you're going to go that route, may as well whip up another PIC to do the tough work for you...
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I'm trying to make an alarm system and I don't want it to be limited by to few switches. Now I know everyone is going to say how many doors do you have that you want to put a sensor on. Well its only 3 so far but there are other things like outside gates, garage door, mailbox (then I can have my computer go "you've got mail" and it be real mail ... lol). I'm sure there are other things as well but thats all I've got right now. If i'm going to use up eight pins I might as well get as many switches as I can out of them.
The using a whole other pic might not be a bad idea. hmmmm
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Well, if you've got a batch of precision resistors, theoretically, you could get 1024 switches on each analog input pin on a PIC with a 10bit ADC.
Or a 74C150, 16 switches per pin, 4 pins, 4 select bits, 64 switches total. But again, a secondary PIC might be easier.
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I don't recommend using analog for this application, due to the false allarms generated the system will result useless. Stay on digital!
Al.
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Well, I don't recommend it either...but it is possible. Yes, it would be noisy. Ya think a filter might work?
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