GPIO software debounce

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does anybody know if it is possible to use software debouncing in the gpio-plugin?
I know that the onoff module supports debounceTimeout:

https://github.com/fivdi/onoff/issues/27

i am trying to find out how to get the debounce timeout set in the plugin? somebody have an idea?

@djazzz said in GPIO software debounce:

i am trying to find out how to get the debounce timeout set in the plugin? somebody have an idea?

I have implemented the feature for GPIOSwitch and you trial it by installing my fork. mwittig/pimatic-gpio
See also https://forum.pimatic.org/topic/1114/updated-how-to-install-a-plugin-from-github-using-npm-or-git
Please let me know whether or not it provides the expected result

Thank you!!
I changed my contact-sensor to the switch device, for the purpose of testing.

i just installed it, i`ll let you know how it works!

i am trying to figure out how your plugin connects to the onoff module…
is there a wiki or something how to do that? i have found tutorials on node.js / coffeescript, but i don`t get how a plugin can use the underlying modules…

@djazzz said in GPIO software debounce:

i am trying to figure out how your plugin connects to the onoff module…
is there a wiki or something how to do that? i have found tutorials on node.js / coffeescript, but i don`t get how a plugin can use the underlying

See https://github.com/mwittig/pimatic-gpio/blob/master/gpio.coffee#L47-L49
I can add similar for GPIOContact and GPIOPresense

I have implemented it for GPIOPresence and GPIOContact too

Example:

   { 
      "id": "contact-sensor",
      "class": "GpioContact", 
      "name": "contact detector",
      "debounceTimeout": 50
      "gpio": 18 
    }

I solved this with a rule back when I was using GPIO directly

if xxx is closed for 50ms

@djazzz did you have some time to trial the changes?

i am experimenting with the bouncetime, i had 200 ms now i am on 500ms…

Problem i have is that i run a long cable through my garden to a magnetic doorcontact on a gate. it is connected normally closed. with internal pullup activated.
For no apparent reason the input triggers once in a while…
I think the long cable picks up some noise sometimes.
With bouncetime set to 200ms , i still had an problem, yesterday i put it on 500ms. so now i am waiting to see if it stays ok.

do i understand correctly that , this function ignores active input until it stays active more than bouncetime?? 500ms in my case…

@thex

how did you work with the gpio directly? did you use interrupt-driven programming?

perhaps if the debounce-function isn`t working correctly i have to work with gpio directly…

@djazzz said in GPIO software debounce:

do i understand correctly that , this function ignores active input until it stays active more than bouncetime?? 500ms in my case…

Yes. However, a 500ms debounce is really hight. Are you still using the GPIOSwitch for testing purposes? Make sure you have the “right” version in place, i.e. make sure /home/pi/pimatic-app/node_modules/pimatic-gpio/device-config-schema.coffeecontains the debounceTimeout property definition for the device type in question.

@djazzz said in GPIO software debounce:

perhaps if the debounce-function isn`t working correctly i have to work with gpio directly…

Maybe the following thread is helpful as it also bases on using ofoff (without debounceTimeout, btw.) and has a cable length of roughly 10-15m. The thread also includes a schematic which you may want to try:

                                               ------------------------------+3.3 volts pin on Pi
                                             |
                                             |
                                10 K pull-up resistor (or internal)
                                             |
        -----330 ohm resistor-----+------------------------------ GPIO Pin on Pi
        |                                   |
     switch                                 |
        |                        10 nF capacitor
        |                                   |
          +---------------------------+-------------------------------- 0 volts = GND = Ground, pin on Pi

https://www.raspberrypi.org/forums/viewtopic.php?f=44&t=49722

EDIT: You should also consider taking further measures against interference, e.g. use twisted pair or shielded cable.

yes, i have debounce timeout with all devices.
cable is twisted pair, but not shielded. i`ll let you know if it works as expected…

@mwittig

so far so good, the last couple of days i didn`t get any false positives on the input.
I settled for 350 ms.