bottomfeeder

demo video of the synthesizer with a control panel added on top is here. Note the synthesizer is mounted to the back of the panel in the video.

Features include:

• 3x 16 bit digital Wavetable Oscillators (sample rates up to 200k samples/sec)
  • Fine and coarse tuning controls for each oscillator
  • user loadable waveforms
  • 1 square wave sub oscillator for each oscillator
• Full analog 4 pole resonant low pass filter
• ADSR envelope generator mappable to filter cutoff and VCA
• Monophonic and 3 voice Paraphonic modes
• Glide rate control
• 2x LFO (also any user loadable waveform)
  • Mappable to many parameters including rate or depth of the other LFO
• Headphone output
• External input to filter
• All parameters controllable via Standard MIDI
• Header connections for modification
• Loading and saving presets
• Low cost and small form factor

Structure

An ARM Cortex M0+ microcontroller acts as a host processor for an FPGA-Based synthesizer. The FPGA outputs the oscillators as well as PWM control voltages for the analog filter and analog VCA parameters. Click here to view PDF schematics.