Bare Metal Gives This Pi Some Classic Synths

We’re used to seeing the Raspberry Pi crop up in a wide range of the projects we show you here, but it’s fair to say that they usually feature some sort of operating system. There’s another way to use a Pi, more akin to using a microcontroller such as the Arduino: by programming it directly, so-called bare-metal programming. MiniDexed is an example, and it copies a classic Yamaha professional synthesiser of the 1980s, by emulating the equivalent of eight of the company’s famous DX7 synthesisers in one unit. It takes almost any Pi, and with the addition of an audio board, a rotary encoder, and an LCD display, makes a ready-to-go unit. Below the break is a video of it in operation.

It’s fair to say that we’re not experts in Raspberry Pi bare metal programming, but it’s worth a diversion into the world of 1980s synthesisers to explore the DX7. This instrument was a staple of popular music throughout the 1980s and was a major commercial success for Yamaha as an affordable FM synthesiser. This was a process patented at Stanford University in the 1970s and subsequently licensed by the company, unlike other synths of the day it generated sound entirely digitally. It’s difficult to overestimate the influence of the DX7 as its sound can be heard everywhere, and it’s not impossible that you own a Yamaha FM synth even today if you have in your possession a sound card.

Curious about the DX7? Master chip-reverse-engineer [Ken Shirriff] exposed its secrets late last year.

18 thoughts on “Bare Metal Gives This Pi Some Classic Synths

  1. nice! A lot of expensive equipment replaced with a tiny little box. I checked on ebay, these things are going for $2000+, it’s insane what people want for old technology.

    1. FM synths in general are infamous for not being tweakable. This has one encoder, and if I’m not much mistaken, I believe the FM7 does as well. But unlike the FM7, this can be rewritten to change that.

  2. Been enjoying playing around with this. Happened to have a pi4 sitting around from a stalled project.

    Just need to mount it in/on a dedicated controller. Just waiting on midi parameter editing to be implemented. Great project and it will have a place in my setup.

    1. Someone has ported the original Dexed to the Pico (see: and there is also microDexed for the Teensy (see:

      I’ve not used either, but I’ve played with the circle-based MT32-Pi and other “bare metal” synth projects (see my own blog).

      MiniDexed will apparently support the original RPi too, but only with a single tone generator rather than 8, but I’ve only used it so far on a Pi 4 myself.


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