STM32 Digital MIDI synthesizer

 In this post I'll document the proccess of making my digital synthesizer based on a STM32 microcontroller.


The synth is capable of producing a square wave, a triangle wave and drum sounds and it's aimmed at chiptune music.


CONCEPT

The board contains the microcontroller, the digital to analog converter (DAC) and the pin header connectors for the components mounted on the panel.



Eagle schematic for the whole board. The choice for the opamp was not correct. The best choice for the job would be a TL071.


                                                                    The board layout

CONSTRUCTION

The board was made in a CNC machine.


The copper traces where coated in silver nitrate to prevent oxidation.


Full assembly with the panel.

CODE

A 25k hertz timer triggers a routine that, based on the panel configuration and input from the keyboard, generates a sample.

The synth can take standard serial MIDI.

The full code can be found on my github: https://github.com/Shiro-pb

And it's still a work in progress.

Planned features include: polyphony, a sequencer and some form of filter implementation.


















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