USB armory JTAG port
1 minute read

When reading further on the USB armory and thinking about the cool things I could do with it, it struck me that I couldn’t find any information on the JTAG port. There are a couple of pads on the bottom side that appear big enough for this purpose, but the documentation do not mention anything on them. A quick google revealed a tweet that confirmed my suspicions:

Sweet! All that is left is figuring out what pins map to what JTAG function. Given that the hardware of the USB armory is completely open source, we can simply open up KiCad and determine the mapping ourself. For convenience, I’ve created an image that shows the functions:

USB armory JTAG layout (bottom view)

Note that this image shows the pins as viewed from the bottom side of the PCB. All is left is create a proper shim that allows us to connect to the JTAG pins, preferably without soldering…

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