SQK-01
The new version of the SKQ-01 FM synthesizer. This time I re-purpose an EMU Xboard MIDI controller to act as the main control for the synth running on an Arduino Due.
The YouTube demo video can be found here.
A video about hacking the EMU Xboard can be found here.
This page is a work-in-progress. More is coming.
The EMU Xboard
I had this thing gathering dust for a while, so I figured I could repurpose it for a DIY synth. However... I did not expect to be able to re-use all the front panel circuitry so easily.
Before I begin, here's a bunch of files you may need:
SQK front panel Arduino code: download.
Reverse engineering notes and schematic drawings: download.
Due pinout, diode matrix configuration and connections in SKQ-01: download.
With that out of the way lets look at the real magic that is hidden in the Xboard controllers:
Yep: that is an Atmega48 MCU, of the AVR flavour.
The programming header connections are also exposed on the PCB itself, you just need to solder on an header (or cables to a connector) if one is missing to be able to reprogram the entire front panel.
No other changes were needed!
You get a very nice setup with 16 potentiometers, a slider, pitch bend and modulation wheels (a joystick in my case), a bunch of buttons and a 7-segment display.
The Atmega48 does all the mux and scanning magic for the 16 potentiometers as well as the ADC conversion. In terms of hardware there's really not much going on.
Here you can see my setup for reprogramming it. Very simple as you can use an Arduino (Uno) as an ISP programmer.
The Arduino IDE even provides you with a one-click solution to program and configure an Arduino board as ISP programmer.
You can also see the two main connectors at the top of the PCB. Most of the connections are the diode matrix for all the buttons, signals for the LEDs and finally a serial interface for the Atmega48 and whatever it communicates with (Arduino Due in my case).
See above downloads for the pinouts and for how the diode matrix is setup.