Sometimes I wonder why

one panel, one control, one voice, it should be easy!Sometimes I wonder why i do these mad things. I mean building synths.

For example, I’ve just speant about 3 hours trying to figure out a problem with the panel. I’ve made some headway, but come up against a brick wall.

Basically the Synth is split into three parts, a panel, a controller and a voice. The Panel reads the knobs and switches and sends data to the controller. The Controller reformats this, adds in MIDI and Patch recall from NVRAM and sends it to the voice. The voice, well, it makes the noises.

Now when I turn the filter cut off knob, the filter cutoff changes, turning an oscillat waveform knob changes the oscillator waveform. So the comms is working Panel -> Controller -> voice. But for some utterly insane reason I can’t get the panel to read the values that the controller is sending out to the voice!

I’ve checked the baud rates all match, I’ve check the correct protocols are all being used and I can’t find a thing wrong!

Why is this important? well, remember the controller is handling the patch memory, so when you recall a patch the data is sent direct to the voice, the panel needs to ‘listen’ to this data and light up the correct lights and values.

I’ll sleep on it for a few days, maybe inspiration will come to my resuce.

6 Responses to “Sometimes I wonder why”

  1. rĂ³bert Says:

    Why do you do these mad things???

    Defender is one of the most beautiful synths i ever saw, please can we have a closer look? Had to tell you, good luck with it all…

  2. Paul Says:


    What would you like to see? the panel work hasn’t progressed much.
    GorF was created for two reasons, firstly to test MIDI for synths I build and secondly so I could work on multiplexed display systems on a simple, small, scale before retrying this with it’s 100+ LEDs.


  3. gerry murray Says:


    Thought you might be interested in the TI multichannel LED Drivers. I’ve used the TLC5940 and it’s really easy to use and saves processor overhead form having to service multiple LEDS.
    The TLC5940 handles 16 LEDs but I see the TLC5947 handles 24 LEDS. 4 of those cascaded would be a really easy way of driving 96 LEDs. If you’re interested, I’ve written a ‘C’ driver for these devices.

    I’d like to say thanks for making the source code available for your MIDI2SDS unit and the MIDI ‘gotchas’ that you published. It helped me get my PIC MIDI/CV converter going.


    Gerry Murray

  4. Paul Says:


    thanks for the offer, I’ll take a peek at the datasheet, thanks.


  5. Dennis Says:

    Hi Paul

    Are you still gonna work on this project?
    I love to see it done one day!



  6. Paul Says:


    Many thanks for your support. I will be working on it soon, GorF has sort of taken over my spare time at the moment.