2024 Business Card Challenge: Tiny MIDI Keyboard

The progress for electronics over the past seven decades or so has always trended towards smaller or more dense components. Moore’s Law is the famous example of this, but even when we’re not talking about transistors specifically, technology tends to get either more power efficient or smaller. This MIDI keyboard, for example, is small enough that it will fit in the space of a standard business card which would have been an impossibility with the technology available when MIDI first became standardized, and as such is the latest entry in our Business Card Challenge.

[Alana] originally built this tiny musical instrument to always have a keyboard available on the go, and the amount of features packed into this tiny board definitely fits that design goal. It has 18 keys with additional buttons to change the octave and volume, and has additional support for sustain and modulation as well. The buttons and diodes are multiplexed in order to fit the IO for the microcontroller, a Seeed Studio Xiao SAMD21, and it also meets the USB-C standards so it will work with essentially any modern computer available including most smartphones and tablets so [Alana] can easily interface it with Finale, a popular music notation software.

Additionally, the project’s GitHub page has much more detail including all of the Arduino code needed to build a MIDI controller like this one. This particular project has perhaps the best size-to-usefulness ratio we’ve seen for compact MIDI controllers thanks to the USB-C and extremely small components used on the PCB, although the Starshine controller or these high-resolution controllers are also worth investigating if you’re in the market for compact MIDI devices like this one.

17 thoughts on “2024 Business Card Challenge: Tiny MIDI Keyboard

    1. And it was GOOD, because MIDI used to be optically isolated, which meant that plugging in a MIDI cable wouldn’t create a ground loop in your system. Now we use USB, which is not isolated. :(

      1. There’s usb midi, there’s OS driver midi, there’s DIN5 midi. Same protocol, but over different hardware or software systems. DIN5 is the best imo, less jitter, opto isolation protects your equipment. USB is good enough, but it’s crap at SYSEX time messages. It drops and jitters the 96ppqn signals. OS midi can happen between software, and is about as good as USB midi. If you want solid timing and low latency DIN is the only good option.

    2. MIDI 2 generalized the interface into something that could be done over USB. Which is good because said giant DIN had required currents instead of required voltages and more-or-less demanded opto-isolation to implement correctly.

      1. “giant DIN had required currents instead of required voltages and more-or-less demanded opto-isolation to implement correctly.”
        You say that like it is a bad thing.
        1. Current loops have better noise immunity.
        2. Optoisolators prevent ground loops and protect your equipment.

      1. Turning buttons into diodes – neat! ;)

        Very nice project BTW. Some time ago I was looking for cheap portable keyboard of small size for travel to play a bit with trackers. If this had additional octave I would be more than tempted to buy. Not implying anything but maybe there is a market (with some profit) for this? I can already imagine acrylic cover that makes it a keyring or backpack zipper pendant.

          1. My first thought with this was “Can I use this as a lighting controller with LightKey?” (Or any other software, really.

            This is super cool, well done!

            The buttons look like they don’t require much force to actuate, are they clicky buttons, or are they capacitive?

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