A week or so ago we featured an FPGA MIDI interface. Since then the builder has gone crazy with his FPGA and revised his code to include polyphony and PWM output, and posted a polyphony demo.
In our previous coverage of the build, the synth was monophonic, and the MIDI implementation was pretty shaky. After realizing the hard work was done, [Mich] re-wrote the MIDI interpretation module to keep 8 voices in memory. Now the synth can play 16th note arpeggios at 999bpm.
The original build used 8 pins to output the audio with an R/2R ladder for a digital to analog converter. This didn’t work well with a polyphonic synth (everything was clipped or noisy), so [Mich] moved to PWM output.
[Mich] plans on building a PCB for the PWM mixer circuit and adding the ability to receive velocity data from the sequencer. He’s also thinking about adding a sampler to the build, but isn’t quite sure about the best way to implement that. If you have an idea for [Mich], leave it for him in the comments. Check out the video below for a demo of the FPGA synth playing Popcorn.
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Filed under: hardware, musical hacks
