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Thread: Convert old 25 note pedalboard to MIDI?

  1. #11
    pp Pianissimo peterb_2795's Avatar
    Join Date
    Nov 2017
    Bathurst, NSW, Australia

    Hi NTL,

    I have read this post with much interest as I am in a kind of similar situation in that I have a 25 note pedalboard (off a C3) that I want to wire as both a midi controller *and* a midi synth audio output device, the intent being that the pedal board can act as either a midi controller connected as an input in some cases and in other situations, as a stand-alone audio source.

    I had concluded (as you did earlier) that one of the midi kits offered by would be the way to go. They provide two pedal kits (complete including wiring) for EU165.00 (reed switches) or EU190 (hall effect). If I were to add up all of the separate parts and postage costs to acquire similar, I would not be saving much in dollars but having a better learning experience. I would be interested to see a few piccies of what you have eventually ended up with from both a wiring and an integration perspective.

    I have of course done the usual web searches and see that there are a number of excellent projects out there that all seek to provision a midi encoder using Arduino, Teensy or SBC's. There is a well documented project at but even then, the author later says that he moved to a Teensy board.

    I would be keen to hear how much time was invested in wiring the reed switches and as to how you arranged them for your case. For the cost of the kit from midi boutique, I might be better off taking that as a convenience route for the encoding and investing more of my time into the midi output side. My initial thoughts for obtaining a stand alone environment are to take the midi controller signals into a Raspberry Pi board that is running FluidSynth (Linux/Raspian) to produce my pedal tones and (say) string bass analog output. The Pi comes with an audio out chip onboard plus, if this is found to not be up to scratch, there is the HDMI output that could be put into a splitter for improved audio quality.

    I think it would be pretty neat to have a 25 note pedalboard that I can use under a re-cased (and modded) M100 or a (to be) Oakland style rebuild (ex C3). Note: original cabinets have (and will be) gifted into our small Hammond community (here in Oz) for re-use.

    At this point, I am assuming that the audio out would simply feed into the input RCA located at the expression pedal housing and I would be on my way (I'm sure there will be gotchas like synth library, waveform and actually getting something that has the deep tones/frequencies of the pedals with all of their "fartiness").

    Either way, thank you for sharing your midi pedal board adventure, you have certainly provided me with some food for thought and a desire to put a midi pedal board onto my "ToDo" list ...

    1966 C-3 / 925
    1965 M102 / 145
    1967 M111A / 330

  2. #12
    ppp Pianississmo NTL2009's Avatar
    Join Date
    May 2016
    N Illinois, USA

    Thanks for your interest. I'll give a quick reply now, as I've got a few things taking my time today, and will try to get more details to you later. At this point, since I have a few other projects in the works, I guess I should look for a blog or website to publish this stuff, describing on a forum will get a little awkward I think. I'm not sure what is best for that, a google site, hackaday, instructable, other? Any suggestions?

    I think for a one-and-done deal, the midiboutique products look pretty good. But like you, I was also interested in the learning experience, and now I'm really glad I did, as it was pretty simple, and the knowledge I gained gave me the confidence to take on some other projects (I'll describe a bit below, and start a new thread on those).

    As an example, I now plan to add a MIDI-MERGE function to this pedalboard encoder, to free up a MIDI input on my recently purchased Crumar Mojo61. I'll run my lower keyboard (a DX-7 used as a controller only for now) into the merge, so pedals and lower keyboard use only one of the two MIDI-IN on my Mojo61. That keeps the other MIDI IN open for my other project.

    Overall it was pretty easy. Wiring the reed switches was not a lot of effort (I used a ribbon cable with connector on one end, so I could unplug the board from it), but the mounting was more work. I ended up with a separate little 1/4" thick board with a slot and screw so I could adjust each one, and the ends of the pedals are not the same length due to the radial layout, so I had spacers on some, and it was all a bit more 'tweaky' than I would have liked. But the Hammond pedalboard might be a bit easier to use? The Yamaha pedals have a metal tab at the end to press the switch in the console, I found just sticking the magnet on that piece would trigger the switch - but maybe it also made the magnetic field wider and I may have been better off removing those and sticking the magnet onto a non-magnetic material? But in the end, it has been working well.

    The ESP 8266 is cheaper than the Arduino boards ( ~ $5), has good support with the Arduino IDE, and is fast (80Mhz processor). In the testing I did yesterday, I could loop on a MIDI in about 105,000 x per second, and when I tried my hardest to overflow the input with continuous control data, which runs from 0 through to 127 (pumping the swell pedal which throws out a LOT of data, and simultaneously pulling 9 drawbars in and out as fast as I could), I never, ever got any bad data, and it was still managing about 90,000 loops per second under full load. So I don't think that will affect the timing of reading my pedal switches ( I will put the in between each switch check and not wait for a full switch scan, as I might lose some MIDI data during that ~ 2.5 mSec full scan). Math says that should only add ~ 0.25 mSec to my current ~ 2.5 mSec scan time.

    I'm using 16:1 MUXes rather than the shift registers in that hackaday link, not sure of the pros/cons for switches (lower GPIO pin count maybe- shift registers use SPI I think?), but since I also plan on reading pots, I need the analog switch capability of those MUXes.

    I have a few lines of code to catch bad data, which I got plenty of when I put print statements in the loop (which slows the response), so I feel confident it is working as expected.

    Note that I have not done anything with audio on these projects, these are strictly MIDI data in/out, driving keyboards to produce the sounds.

    The ESP8266 also has wifi, which I have not used in for this project (I did for another non-music project), but has potential. It also has a basic file system, which I'm, using to store presets on the my drawbar expander project.

    My drawbar expander project has some unique functions (described a bit in an above post). That is coming along well, and I'm about ready to order the hardware (I've kind of mocked it up to test the code, w/o a full hardware set-up). I'll start a new thread on that when I get a little further.

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