So one of the driving components (pun intended) of the derby timer is the LED displays. I went with the smaller ones from Adafruit, as we wouldn’t need a second power supply if we go this route, and I’d like to keep the unit as simple as possible.

You have to solder the displays to the backer board, and then you have to solder jumper pins across them to serialize each display. If you don’t do this part, your displays all show the same thing! I found that out the hard way! So be sure to solder those little jumpers. For convenience, the PDT website:

has a reference table:

PDT Lane # PDT Lane # I2C Address # Jumpers
A0 A1 A2
1 1 F 0
2 2 F 1 x
3 3 F 2 x
4 4 F 3 x x
5 1 B 4 x
6 2 B 5 x x
3 B 6 x x
4 B 7 x x x

Key: – = open, x = shorted; F = front, B = back

This is really handy. I really appreciate all the work they put into this, and it is fun to build along with a guide that covers about 95% of the process!

Linux – keep it simple.

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