Button Pad Sequencer – LED Fade Test


Here’s a brief update on a standalone MIDI sequencer I’m working on – the 4×16 grid of tri-color buttons is finished, and allows for 12-bit color fading. It looks very pretty to see in action, and I can’t think of any button controller out there at the moment that can do this.

If the above doesn’t load quicktime is acting up… just click below for the same vid 😉
Button Pad Fading Test

The button pads are pretty standard sparkfun pads with their accompanying boards. However, the breakout boards from sparkfun are built for multiplexing, which makes controlling them slow and not as bright, and very difficult to fade. I designed a ‘companion board’ to attach to these (with some modification), and provide connections for 3 TLC5940 LED drivers.


This works nicely with the arduino TLC5940 library here.

If I were to do this again, I could probably do this with a single board, removing the need for the sparkfun breakouts, by using the SMD version of the TLC5940s. It’s extremely tight with the DIP package above. I’d also need a PCB manufacturer that could do plated contacts, and I haven’t found one in the UK yet.

If anyone is interested in having some made up as well, send me a message. I got these printed up at PCBTrain in the UK, who did a very nice job.

4 Responses

    • Hi Scott,
      The PCB’s were never available, I just had 4 of them printed up for this project. I’ll see if I can dig up the schematics – keep in mind they are designed to fit underneath the sparkfun button pad circuit board. It would be easier and cheaper to make a single board that did everything. You’d have to find a printing service that does a conductive coating for the contacts, and the design would probably have to use the SMC version of the TLC to fit everything in. What are you working on?

      • Scott O'Hair says:

        Thanks for the reply. I am running 5 of the sparkfun boards in a 4 x 20 arangement and really was dreading the amount of chips that I would need to power common cathode RGB LED’s. I ended up using addressable LED’s and changing the way the board is laid out. Much easier!!

  1. Drew Alden says:

    Hi, I’m very interested in making something like this – looks brilliant! Did you find the schematics? Do you have an updated single-board one like you mentioned making? I wouldn’t mind throwing you a couple bucks to design a chainable version of Sparkfun’s board :)

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