TURNIPSCHOOL

Scope
TURNIPSCHOOL is a hardware implant concealed in a USB cable. It provides short range RF communication capability to software running on the host computer. Alternatively it could serve as a custom USB device under radio control.

Status
A fully functional prototype was presented at ShmooCon 2015: http://www.shmoocon.org/speakers#usbtools

Ingredients
USB Cable with the A connector cut off
3D Printed mold for overmold boot: https://github.com/kikithegecko/turnipschool-casing
Silicon overmold material: http://sugru.com/
C clamp
Cooking oil or other mold release agent
Optional: heat shrink tubing

Assembly Instructions
step 1: Assemble PCB. For operation near 900 MHz, solder one end of an 8 cm wire into the antenna port.
step 2: Wire GoodFET to PCB (refer to TURNIPSCHOOL schematic and layout and the pinout at http://goodfet.sourceforge.net/clients/goodfetcc/).
step 3: Install bootloader with goodfet.cc.
step 4: Use the bootloader to install rfcat or other application firmware.
step 5: Fully test both the bootloader and application firmware.
step 6: Solder wires from USB cable to PCB (refer to TURNIPSCHOOL schematic and layout).
step 7: Test downstream USB functionality.
step 8: Optional: Install heat shrink tubing around PCB to ease future removal of overmold boot.
step 9: 3D print 2 sides of the mold for the overmold boot.
step 10: Coat inside of mold with mold release agent such as cooking oil.
step 11: Form overmold boot around PCB by hand.

Credits
schematic: Dominic Spill (@dominicgs)
layout: Michael Ossmann (@michaelossmann)
overmold boot design: Karoline "kikithegecko" Busse (@kikidergecko)
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