MonoTon

Arduino based step sequencer and software-synth

Video on youtube:

(Audio only).

Features

• 8 instruments (Kick, Hat, Snare, Shaker, Clap, Noise, Sine, Square)
• Each instrument has 4 banks a 16 steps each and can be muted
• Synthesis using 8bit wavetables
• 20000Hz sampling rate
• Master is filtered through analog high-pass filter (2pole)

Hardware

• atmega1284 @ 16MHz using Mighty1284 platform
• lots of 74HC595 shift registers (for LEDs)
• MCP23S17 port extenders (for buttons)
• CD4067 multiplexer (for analog potis)
• R2R network for D/A conversion
• Some eagle files included

Lessons learned while developing

• The analog inputs are quite noisy. De-noising uses quite much cpu.
• Don't ever solder this much wires by hand. PCB services are your friend.
• Prefer DDS over an R2R ladder.

Open bugs / flaws

• Although the output is buffered by an opamp, the sound sounds distorted when using the PC's line in. If I conntect it directly to the speakers, the sound is quite clear.