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