Sensor hookup

I've been reading with interest all the clever solutions to interfacing the tiny connector on the end of the vibration sensor cable.  I had also ordered the recommended SMD mating connectors.  When I received the connectors, I pretty much decided that I couldn't easily make a robust adapter so I was just going to cut the existing connector off and attach a larger Grove connector because I have lots of cables and boards that use the Grove system.  I've recently been using a lot of boards with Grove and Qwiic (Stemma-QT) connectors - most recently on the Adafruit QT Py.  I had purchased a Sparkfun Qwiic adapter board  to allow me to interface breadboard jumper cables to Qwiic sensors.  It turns out that the Qwiic coinnector is a 4 pin version of the 3 pin connector on the vibration sensor cable and that cable will plug into the adapter as I've shown below.  Of course, you have to be careful to use the correct 3 pins and I had to make SCL the GND pin but otherwise it's a mechanically robust solution.


I printed a holder for the adapter board to keep it stable (flat) when I attach jumpers or probes to it for testing.


In actual use I'll probably use the other Qwiic connector (obscured by the housing) with an adapter cable to a Grove connector which I can plug directly into a Wio Terminal for data collection and processing.


I also attached the sensor body to the mounting plate that I had printed using double sided thermal adhesive tape (because it works well as double sided tape).  And I added strain relief for the cable.  Here the mounting plate is shown attached to the riser on the microphone stand.



First test

Before diving in to data collection I thought it would be good to sanity check my setup with a scope.

We expect the sensor signal to be about VCC/2 (+1.65V) and swing +/- around that level.

Here is a scope capture of the response to a quick tap on base of the stand.


The quiescent DC level is +1.7V which is good.  I'm a little concerned about the quiescent noise level.

Here is a closer look at the noise:


I then tried tapping about 18 inches away from the stand on my wood desktop.


It will be interesting to see if I can discern footsteps on my hardwood floors.  Time to start working on a program for data collection .



Links to my other blogs for this challenge

Person Identification using Footstep Vibration Patterns

Vibration Sensor Setup