The Smallest MIDI Synthesizer?

Dang. [Mixtela] has just managed a seriously cool hack: running an entire MIDI synthesizer on an ATTiny85 to create what he claims is the worlds smallest MIDI synthesizer. That’s it on the left, next to a standard MIDI cable plug. microMidi3-guts-thumbThe whole thing is so small it fits inside a MIDI plug and can run off the power supplied by the MIDI output, driving a small pizeo buzzer. Considering that the ATTiny85 has just 8Kb of memory and 512 bytes of RAM, this is no small feat (get it?). To create the sound, [Mixtela] simply drives the buzzer with PWMed square waves, creating the glorious early chiptunes sound that every retro gamer will recognize.

He even decided to implement some MIDI commands beyond just playing notes, including pitch bending, and is considering ways to add polyphony to his small miracle. Sure, it isn’t going to win any awards for sound quality, and without optoisolators it doesn’t really fit the MIDI spec. But it works, and remember that MIDI synthesizers used to be big, expensive devices that required a degree in sound engineering to program. Now, thanks to hackers like [Mixtela], you can build your own from parts that cost only a couple of dollars.

33 thoughts on “The Smallest MIDI Synthesizer?

    1. It doesn’t. It runs off the power supplied by the MIDI port. IIRC the MIDI spec indicates that you can draw something like 200mA from it. I think it is known as phantom power or something. Also in the MIDI spec is that you need to put in optical isolation. I will agree that there is really no good reason to do so in this case. In fact it would be impossible to power it from MIDI if you did.

        1. It’s not impossible.
          He does it, I do it and Midi Solutions do it.
          As long as the Power consumption stay below 5mA.

          But you can’t power it without breaking the isolation.
          The have to share a common ground and the opto isolator removes that common ground to avoid groud loops.

        1. What’s your distinction between tone generator and sound synthesizer?

          The earliest synthesizers didn’t do much more than a few simple tones either. The only difference was filters.

          1. And attack and decayand sustain, release. Ring modulation and on and on
            I considered a tone generator along the lines of an organ with very simple filtering and nothing else. Piezo oscillilator being controlled by a midi signal is a tone generator.

          2. I don’t think you can draw a hard line, but it’s a bit like asking what’s the distinction between lasagna and a bowl of noodles, are they both “meals”?

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