Comments on: Arduino Knock Lock not working properly

By: Joe

Joe — Thu, 16 Apr 2020 17:49:43 +0000

Hey, thank you for putting this up. I couldn’t get piezo to register anything at all and i couldn’t find where the code was wrong. I pasted yours in and kept comparing with mine until I found the extra = sign somewhere. Thanks for the help!

By: Kris

Kris — Thu, 19 Sep 2019 01:37:19 +0000

Forgot to mention, I just built the circuit on the breadboard, rather than attaching the piezo directly to anything. The upshot of that is you need to make sure the breadboard isn’t moving around, and then produce a defined tap on the piezo, probably with something metallic or rigid plastic. For me, tapping it with tweezers worked, but not my finger for instance.

By: Kris

Kris — Thu, 19 Sep 2019 01:33:45 +0000

Thanks, the key for me was in adding a delay after incrementing numberOfKnocks:

if (checkForKnocks(knockVal) == true) { // Validate the vibration as knocks with a custom function.
numberOfKnocks++; // if they’re valid knocks, then increment the knockCounter.
delay(200); // This was key to reducing in the noise and making it detect knocks
}

I ended up using these for the knock detection thresholds:
int quietKnock = 150;
int loudKnock = 5500;

By: Kathy

Kathy — Wed, 24 May 2017 00:55:08 +0000

Thank you so much for your code improvements. My project works now.