Pogo pin debug jig for Hubsan Q4 / Estes Proto-X micro quadcopters

Jig to solderlessly attach to the CPU debug pins of the Hubsan Q4 or Estes Proto-X quadcopters for hacking. Useful for working with bradwii firmware.

My Proto-X looks like it has a conformal coating over both side of the board, including the test points. But that doesn't seem to stop the sharp conical point pogo pins from making contact and talking with the debugger.

Update: WIP Bradwii port to Q4 / Proto-X here. Sort-of works, needs some minor fixes and PID tuning. Contributions welcome!

Instructions

Parts:

-Sparkfun pointed tip pogo pin - other tips would work too. Order at https://www.sparkfun.com/products/9174 . Will need serious tweaking to use with pogo pins of different lengths and diameters.

-Small gauge wire of some sort. I used a CDROM audio cable from the junk bin since it has 26ga stranded wire and terminates in Dupont socket pins which fits my SWD adapter nicely.

-An SWD JTAG adapter. I use the STLINK/V2 adapter since I have a devkit with one built in and it's supported in OpenOCD.

-Rubber band or velcro cable tie to hold the copter in the jig

Pins:

swclk - "C" on the board - SWD clock
swdio - "D" on the board - SWD data
gnd - unlabeled pad on the board - system ground
vcc - "+" on the board - 3.3V from after the regulator

Construction:

The pogo pin holes are narrower at the ends to make it easy to ream them to size with a hobby knife. Enlarge both ends so the pogo pin fits snugly. Be careful with forcing the pin in as they snap easily.

Solder the leads to the 3mm of the pin body near the plunger, making sure not to let solder reflow onto the plunger.

Use:

If debugging while running on battery power, omit vcc. There's a chance of shorting the battery while loading the copter into the jig, so consider using vcc and detaching the battery first. At a minimum, don't plug the copter in while either end is powered up.

These pins have some play in the plunger, so check that the tips are on the pads before powering up the target.