Pi skin conductivity
- 3 pairs of GPIO pins are used as to capture skin conductivity
- python reads GIOP (should run as a deamon)
- OSC sends messages from py to pd
Pis have no ADC, therefore the simple way to read a Pot's value is via a step response technique as explained in http://razzpisampler.oreilly.com/ch08.html
- Rpi breakout board (cobbler) + cable from GPIO to breakout board cable.
- 1x 220 nF capacitor
- 2x 1Ohn resistor
550 ohm pot (values go between 0-800)OR metal points
notes on RPi GPIO
In model 1 there were only 26 in the following configuration
Model 2 B and 3 B keep the same configuration for the first 26 pins, but expand it to 40 pins, in the following configuration
apt-get install python-pip
Pi python lib RPi.GPIO https://pypi.python.org/pypi/RPi.GPIO
apt-get install python-rpi.gpio
pyOSC (is not on minibian repos )
pip install pyOSC
I am using 500K variable resistor(pot) instead.
In order to use touch pressure: I kept the circuit only replacing the variable resistor with 2 metal pins.
The result is very interesting.
- because the circuit is interrupted while no one is touching, the stream or reading is interrupted
- values can go from:
- Max: 3 (very strong,wet contact) (0 if there is a metal connection )
- Min: 273337
- Pi cobler
Weidmuller PM 5.08 Series 5.08mm Pitch Straight PCB Terminal Block with Leaf Spring, Screw Termination, Through Hole RS-stocknummer: 425-8720 Aantal: 30
Murata Single Layer Ceramic Capacitor (SLCC) 220nF 50 V dc ±10% X7R Dielectric RPER7 Series Through Hole RS-stocknummer: 721-5262 Aantal: 30
RE520-HP, Single-Sided Stripboard FR-2 100 x 160 x 1.5mm FR1 RS-stocknummer: 206-5841 Aantal: 3