Introduction: Circuit Playground Extension - E-Textile Debugging Tool
The Circuit Playground Extension is a tool that enables the user to design e-textile circuitry with debugging in mind. To use the tool, the user would sew the extension into their project with the holes in the extension's substrate matching with the pins that the user wants to connect to on the Circuit Playground. The user would then attach stainless steel thread to the magnet in Circuit Playground pins and to the corresponding hole in the extension. If the project is not working as expected the user can:
1. Remove thread connections to the pins, this will separate power from a particular part of the circuit so that the user can test functionality one at a time (isolation switches).
2. Place an LED in series between a pin and the corresponding hole in the extension. This can tell the user if there is power at a particular part of the circuit (if it can drive the LED).
3. Remove a thread from a pin and place an ammeter in series to measure current.
4. If the user is a student and they have a teacher with a CIrcuit Playground that has the correct code for the assignment, the teacher can easily swap in their microcontroller into the extension and test if the student's code is buggy.
This material is based upon work supported by the National Science Foundation under Award #1742081. The project page can be found here.
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Step 1: Materials
3D printed extension - I used a Prusa MK3S - Link to the STL file
4mm x 3mm magnets - 4 magnets for the microcontroller holder - Link
4mm x 2mm x 2mm ring magnets - 20 magnets per extension - Link
3mm x 2mm magnets - 14 for the pins of the Circuit Playground - Link
Stainless steel conductive thread - Link
Step 2: Adding Magnets to Your Circuit Playground Pins
Now that you have the materials, it's time to add magnets to the fourteen Circuit Playground pins. The reason we are adding magnets to the pins is to (1) hold the microcontroller securely to the magnet enriched Extension and to (2) allow for a magnetic connection between the pins and the conductive thread. Typically, to connect the Circuit Playground with conductive thread you would need to sew and secure the thread around the open pins, and if you wanted to change your circuitry you'd need to cut the thread attached to the microcontroller and possibly resew your project. With the Extension, you can simply drop your conductive thread on top of the magnets and they will keep the thread secure to the microcontroller pins and the ring magnets in the extension.
- Place duct tape on the bottom of your microcontroller then cut around the edge of the microcontroller. The duct tape will be used to hold the magnets within the pins (Figure 3).
- Isolate one disk magnet from the 3mm x 2mm set. Make sure that you have identified which end of the magnet will attract or repel the other magnets, the poles of the fourteen magnets need to be the same so that they are attracted to the magnets in the Extension.
- Gently push the magnet through the pin until it adheres to the duct tape. On a flat surface, apply light pressure on the top of the magnets to make sure they are secured to the tape. Continue this process for the next thirteen magnets.
Step 3: Adding Magnets to Your Extension
Before you can use your extension you need to add the 20 hole magnets and 4 regular magnets to the 3d printed substrate. It's important that all of the magnets have the same pole facing upwards before press-fitting them. Also, make sure that the 4 inner magnets will be attracted to the magnets placed into the Circuit Playground in step 3. To embed the magnets, I recommend:
- Place 1 magnet to the inside of a large pair of pliers (Figure 1).
- Align the magnet over an open hole in the Extension (Figure 2).
- Gently apply pressure until you fill the magnet go into the hole and it is flush with the rest of the substrate (the inner 4 magnets will poke out a bit).
- Repeat these steps for all of the magnets, this should take around 5 minutes.
Step 4: Done!
You now have your very own Circuit Playground Extension! Happy debugging!
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