What do you do when you get given 1000 free 10mm LEDs? I thought it would be cool to make a big 7 segment display, with 3 LEDs for each segment. With a decimal point that makes 22 LEDs per board. The boards are 83 x 120mm.
The board uses a nice constant current LED driver, the TLC5916. Current can be set with R1, which you calculate by reading the datasheet.
The boards can be linked together – I’ve only tested 3 in a row, but that works fine. Here’s a video of 2 being driven by a Raspberry Pi.
The LED enable pin allows PWM for brightness control. Example Python code for driving the boards connected to a Raspberry Pi is available on my github. Driving the boards from other controllers is straight forward – they are the same as shift registers.
If you want to make a board yourself, then have a look at the schematics and gerbers on the github.