Experience interfacing old alarm and Piface?

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EdddieN
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Experience interfacing old alarm and Piface?

Post by EdddieN »

Hello there

I'm trying to use the PIR detector from my old alarm to use them as motion detectors on the Piface. I have measured the voltages and it looks like 6Vdc so probably should be ok.

Has anyone done something similar before? Just thinking whether I need a signal splitter or I may just join the signals.

Any crazy feedback is welcome :D
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Jan Jansen
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Re: Experience interfacing old alarm and Piface?

Post by Jan Jansen »

The maximum voltage on the input pins is 3.3V. You can use a small circuit like download/file.php?id=188 to protect your piface.
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EdddieN
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Re: Experience interfacing old alarm and Piface?

Post by EdddieN »

Thank you!

I did look for documentation re the Piface for max input, all I could see is 5Vdc with optional pull ups to 3.3Vdc
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EdddieN
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Re: Experience interfacing old alarm and Piface?

Post by EdddieN »

Ok, for my setup it looks like I need to put the inputs in tristate mode (external pull up).

Haven read the Piface.conf documentation... there's nothing that mentioned it.

Is there any way to do this?
With WiringPi it was possible to use tristate
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