Charlieplex sort of not working

[ej.cardinal]

I finally got around to assembling my Charlieplex shield, but it has some severe problems. When I plug it in to upload the example sketch, one of the lights flashes on for a second (3,3). While the sketch runs through the sequence sometimes LEDs other than than the current target dimly flash on and off, but I thought this might be because of the nature of charlieplexing. However, when it gets to the LED that flashed on during startup (3,3) that one stays dark and all the others in its row and column light up.


At first I thought I might have soldered the LED in backwards, so I unsoldered it and put in a new one being very careful about polarity and checked all the other solder joints. I still get the same results 


Any hints on what's happening or how to debug?

[digistump]

First try programming the Digispark - then unplugging from the computer and running it from some other 5v (5v pin or usb connector) or 7v-12v (Vin pin) power source - the issue might be if you have it plugged in the computer still, the USB communication is interfering.


Some do light very dimly when they shouldn't, this is a result of the Charlieplexing and the chip being used - but the one not turning on is unexpected. Since you've tried a second LED already I'd look if anything was being shorted from soldering, etc. The boards are 100% tested so it shouldn't be a faulty board.


Let me know if any of that helps,
Thanks,
Erik