Tag Archives: midi synthesizer


LPC1114 controlled Midi Synthesizer

Matt Sarnoff built this digital monophonic synthesizer using the NXP LPC1114FN28 ARM Cortex-M0 microcontroller and MCP4921 SPI DAC. It is a midi synthesizer with following features:

  • 4 oscillators; sawtooth or pulse with adjustable duty cycle with coarse and fine tuning
  • 2-pole (“Chamberlin”) state-variable filter with lowpass, highpass, and bandpass modes
  • Attack-release envelopes for amplitude and modulation
  • Low-frequency oscillator with four shapes (triangle, ramp, square, random)
  • LFO and/or modulation envelope can affect filter cutoff frequency, pitch, and pulse width
  • Keyboard tracking for filter cutoff frequency
  • Glide with 3 different rate presets
  • MIDI input; monophonic with last-note priority
  • 250kHz, 12-bit output
  • Powered by 3 AA batteries
ARM-powered midi synthesizer

ARM-powered midi synthesizer