Button debouncing

[chatmurai]

Hi there,

Nice GPIO library !
Is there any internal mechanism for debouncing the hardware interrupts watch() function? I am having issues with this, and found nothing to get rid of it.

[fivdi]

Hey @8power8, thanks.

The constructor has an option called debounceTimeout. Here is an example of it's usage which works for me:

var Gpio = require('onoff').Gpio,
    button = new Gpio(4, 'in', 'falling', {
        debounceTimeout : 50 
    }),
    count = 0;

button.watch(function(err, value) {
    if (err) throw err;
    count += 1;
    console.log('button released ' + count + ' times');
    if (count === 500) {
        button.unexport();
    }
});

The circuit is similar to this one here, except that the button is wired to GPIO4 rather that GPIO17. Note that the 10KΩ resistor is actually quite important. If it's not there, small movements of the button or the wire connecting the button to GPIO4 can result in tens of unauthentic interrupts.

[fivdi]

Hmm, if you're using the BeagleBone Black, you could give this Button a try. Internally it uses the Linux gpio-keys driver for detecting button events. The gpio-keys driver also supports software debouncing.

[chatmurai]

It works like a charm.
I followed your advice and changed my circuit wiring to a 10KΩ solo resistor instead of 10KΩ + 1KΩ like this one, and this works great too.
One never says thank you too much, so again thanks for this module 👍

[fivdi]

That's nice to hear. I guess the issue can be closed.