Cheep Mod - a low cost platform for Euro-Rack digital audio.

Cheep Mod Cheep Mod

Cheep Mod Front - fully assembled

What is it?

This is a small 6HP Euro-Rack format module with 3 CV inputs, 3 pots, Digital (Sync) input, 12-bit DAC Audio output and Digital (gate) output.


I do a lot of development for various Euro-Rack manufacturers but I've never built an entire module myself. This project was an experiment on several fronts - what's the cheapest yet most capable MCU to use (the one used here costs $0.50) while still providing features that allow advanced DSP, and how well does it work to use PCB manufacturing processes to create a modular front panel? Considering the advanced synthesis algorithms I've been running on this hardware and the decent appearance and assembly of the panel I consider Cheep Mod a success on both fronts.


Software Development

The STM32 family of parts are supported by a variety of commercial IDEs, all of which are available in low-cost or limited free versions from the ST website.

I prefer to use open-source tools so I've set up a development environment based on the GNU C compiler for ARM, available for free from the Launchpad project. For downloading to the target I use OpenOCD and the ST-Link V2 SWD interface that's available on most all of the inexpensive STM32 Discovery boards. To accelerate development I also use the STM32 Standard Peripheral Library as a starting point for my code and then optimize out the heavyweight functions as required. Links to all of these are here:

Design Resources

Project Status

Return to Synth page.

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Eric Brombaugh

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