Old school Hand Clap

Andrew_Pawelski · March 17, 2018, 12:24pm

I have a rule that turns off a light after an expire binding finishes during the day. Sometimes there is a need to have the light on during the day and I have found I am usually head down in something when the light goes off. At the moment I have to either change a motion sensor to detect motion but would prefer to be selective as I dont want my kids turning on the light in the day time.

Has anyone created a cheap old school hand clap sensor to activate a rule in OH?

Spottyq · March 18, 2018, 7:23am

I did make something along these lines. My goal was to knock on the table next to my bed to toggle lights on or off. I did this with a cheap microphone that had a digital output (would get high above a certain sound level.)

My results were mitigated… I had few false negatives, but quite a lot of false positive. The false positives included hand clapping (good for you, not for me. ), the front door downstairs being closed with too much force, and a few other random things like that.

Also, one and two knocks had way too many accidental triggers, so i only used three, four and five knocks.

Andrew_Pawelski · March 18, 2018, 10:43am

How did you make a thing that integrates with OH?

Kees_van_Gelder · March 18, 2018, 10:54am

Most cheap microphone modules come with a digital out that goes high or low when the sound volume crosses a pre-set level.
One could read the HIGH/LOW signal on the digital output with an ESP8266, and MQTT the signal to openhab, or just read it from yr raspberry -that is hosting openhab- with the GPIO binding.

Many, many years ago I made a design from magazine Elektuur, nothing digital, all analog and I remember there was some filtering to specifically select handclapping, but I am sure that also detected or would have detected a slamming door or knocking

Kees_van_Gelder · March 18, 2018, 11:01am

That is a witty way to put your lights on without having to search for your phone with a half sleepy head.
I would think that for your specific goal one of those ultrasound detectors would be better than a microphone. These are also often used for say ‘knock knock doorlocks’.
Quite flat, could fix them on or under your table/nightstand
Edit: they are called Piezo electric sensors

Andrew_Pawelski · March 18, 2018, 10:04pm

Got any links to OH integratable hardware?

Thanks
Andrew

Kees_van_Gelder · March 18, 2018, 10:14pm

I don’t think such ready made hardware exists

vzorglub · March 18, 2018, 10:15pm

The thing with openHAB is that it’s open and you can integrate anything with a little bit of work.
In this case I don’t think there is anything you can buy off the shelf. You are going to have to make your own. I recommend an ESP8266.

Have a look at:
https://www.14core.com/making-your-own-sound-activated-switch-on-arduino/
to get your started
Then you can publish an MQTT message from the ESP8266 to trigger openHAB

github.com

knolleary/pubsubclient/blob/master/examples/mqtt_esp8266/mqtt_esp8266.ino

/*
 Basic ESP8266 MQTT example

 This sketch demonstrates the capabilities of the pubsub library in combination
 with the ESP8266 board/library.

 It connects to an MQTT server then:
  - publishes "hello world" to the topic "outTopic" every two seconds
  - subscribes to the topic "inTopic", printing out any messages
    it receives. NB - it assumes the received payloads are strings not binary
  - If the first character of the topic "inTopic" is an 1, switch ON the ESP Led,
    else switch it off

 It will reconnect to the server if the connection is lost using a blocking
 reconnect function. See the 'mqtt_reconnect_nonblocking' example for how to
 achieve the same result without blocking the main loop.

 To install the ESP8266 board, (using Arduino 1.6.4+):
  - Add the following 3rd party board manager under "File -> Preferences -> Additional Boards Manager URLs":
       http://arduino.esp8266.com/stable/package_esp8266com_index.json

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Spottyq · March 19, 2018, 10:31am

I did it with MySensors. (It was at the beginning of my experimentations with home automation.)

Check this MySensors tutorial to get an idea of what’s involved.

If I were to do it again today, I’d most probably use an ESP8266 (or variant thereof like the NodeMCU, etc.) Advantages are that you directly have MQTT output on WiFi from the sensor (which is easy to integrate with OpenHab.) It also simplifies the node; no need for a separate PCB for the 433Mhz radio.