is a great piece of hardware but if you need to use pads on the bottom facing side of the PCB you will have to get a soldering iron out. I did just that with mine. I used a bunch of female-female dupont cables cut into two and connected them to the pads on the bottom of the Teensy.
This was the end result...
These are some photos of the prep steps, tinning the wires and the pads.
Some of the wires attached...
While I was at it, I added female connectors to all the standard pins. I think this is easier to work with that using male connectors and trying to have the Teensy on top of a breadboard.
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