Table of Contents

IO Board

Schematic Overview:Midi, Sync and USB

MicroProcessor, HeadphoneAndMixer


Most of it is pretty simple. A block diagram would be redundant, as it would show inputs leading to outputs, with exception to the USB, where it goes through the USB chip first.

Mix In/Out and Gate/CV Out

These are pretty simple. Mix In and Out both me through J7 and are connected directly to their respective jacks. CV and gate come thorugh J6, and again, are connected directly to their respective jacks.

Din Sync

DinSync is a single sync connector which doubles as a Sync In and Sync Out. Someone needs to dig into the FirmWare and figure out just which sync lines are in and out.

Midi In, Out, Thru

Midi Out send 5V on pin 4 of the jack. The midi data comes straight from the MicroProcessor and then through a 220 Ohm resistor to pin 5.

Midi In is properly opto-isolated. The Midi signal comes in through the jack, and then goes through a LED in the optoisolator, which activates the base of the PhotoTransistor, allowing current to flow from the collector to the emitter. From the emitter, it enters the base of Q50, Which shorts thhe connection of the +5 Volts to ground. This midi signal is split, one is sent through a 220 Ohm resistor and them the Midi Thru, and the other to the MicroProcessor.


A majority of the circuitry here is straight from the datasheet, which is available here: