We now finally have a panel programming and testing board for the MappyDot panels and future sensors we are working on (before installing pogo pins):
It's a simple but feature packed design. The way it works is that each board has a controllable power supply through a TCA6424A 24-Bit digital I/O expander. This allows for programming and testing of an individual device on the panel (it has also been designed to allow all boards to turn on at once for a purely aesthetic effect with the PWM LED output).
Each of the other I/O pins from every board is then connected on a shared bus which is brought back to a Teensy. This can then test for dry joints/disconnected pins on the currently powered board. Now, because they are on a shared bus, there's no way to identify if a board has a short on a certain pin under test, but this is rare occurrence, so if this happens the panel can be taken out and checked manually.
The test routine is just a script which uses avrdude to program the board and check for errors, then it will run a serial terminal program to run through the pin test (built into the firmware) and i2c data test routines as well as calibration. It cycles through every board and then it flags individual boards for errors that need to be fixed.
This should speed things up over the existing individual board programmer and tester: