this kind of optic fiber is probably only plastic so for a full DIY , you can use also fishing wire with a big power led or an old chistmass tree optic fiber lighted.....
@fets So far, I have only built the 5x5 board (but the others should be schematically identical). The only issue I have found so far is that I cannot get the ISP port to work. But I have checked and I have an identical setup on the 1.0 board and that worked, so I suspect the programmer is too weak to drive the net on this one. So it is not a board-issue per se, and might only be an issue on the 5x5 board as routing is the most complex on that one due to the size.
I think the comment in the routine
void measureBattery() {
// R1 = 1MOhm, R2 = 220 kOhm
Should be
void measureBattery() {
// R3 = 1MOhm, R2 = 220 kOhm
(R3)
Is it possible to add (comment out) some lines how to calculate the battery percentage and send this via gw.sendBatteryLevel (batteryPcnt)
Great sketch!
