Introduction: E-Textile Logic Injector - Debugging Tool
The e-textile logic injector tool enables the injection of a high (1) logical state into a digital circuit. With this tool, makers can simulate a digital write high (digitalWrite (pin, HIGH)) before writing any code. This enables them to test their circuitry for shorts, loose connections, and polarity before adding complexity through code.
To use the tool, disconnect your microcontroller from power (recommended), then attach one alligator clip to your board's GND pin and the other clip to the magnet on the logic injector. Press the probe against any thread that you want to inject a signal into and then press the button on the logic probe to test the component (video).
This material is based upon work supported by the National Science Foundation under Award #1742081. The project page can be found here.
Photo (1 & 2) credit to Elliot Whitehead.
If you want to keep up with my work, or just toss around ideas, please do so on my Twitter: @4Eyes6Senses. Thanks!
Step 1: Materials
1x Custom PCB - while this project can be done with a regular protoboard, if you want to order the custom PCB you need to upload the "LI_GBR.zip" to any PCB manufacturer. I used JLCPCB and it costs about $3 for 5 boards.
1x 6X6X11 push-button switch
1x Red LED (I recommend flat-top LEDs for easier access to the button)
1x 330 resistor (for LED)
1x 330 resistor (in series with the pogo probe, can be changed based on your component current needs)
1x 10x2mm disk magnet
1x Lipo JST header
Step 2: 3D Print Housing
I suggest printing the housing for the logic injector first before completing the following steps. You can also create the logic probe without the housing, but you will need to skip a step later on.
Step 3: Populate PCB
Populate the PCB as follows:
B1: Magnet (I suggest using some superglue to attach the magnet to the board, just make sure not to cover the two pads)
JP1: Lipo JST
VCC: Leave open or attach headers
R1: 330 resistor
R2: 330 resistor
S1: push button switch
Pad: Pogo probe
Step 4: Snap PCB to Housing
Slide the lipo battery into the 3D printed housing (Figure 1), connect the lipo to the JST connector on the PCB and the PCB should press fit into the 3D printed housing (Figure 2&3).
Step 5: Done!
You now have your very own e-textile logic injector! Happy debugging!