Thursday, May 1, 2014

16-Step MIDI Filter Sequencer

The designs for the Step Control Sequencer are at

Following two months developing code and playing with breadboards I present this quick demo of the recently completed DIY digital 16-step control sequencer. This sequencer was designed for controlling filter steps on an MS-20 mini. The sequencer puts out variable step control voltages up to +5 volts and synchronizes to midi start/stop/clock messages. To achieve control over 16-steps with only 8 pots, I employed a toggle switch that can program steps 1-8 or steps 9-16 without reading changes until the pot positions are changed. All the control processing happens on the Arduino Mega. I have prototyped two circuit boards for this project. The first is a midi shield. The midi shield features one minijack control voltage output, one midi input with an opto-isolator, and one midi thru port. The second board I made is a panel control used for the pots and LEDs. The Arturia Beatstep is the master clock and is sending midi note data to the MS-20 at the same time the step-sequencer is controlling the filter with control voltages. The Sequential Drumtraks is put in slave mode for this demo.