SQ80 Hardware Programmer

PG-80 Crosswave Parameter Programmer for Ensoniq SQ-80 and Ensoniq ESQ1

This repo contains open source hardware and software for the Ensoniq SQ-80 and ESQ-1 hybrid synthesizers, which I have named the "PG-80". It allows you to program up to 63 parameters in your synthesis engine using the 32 knobs on the front panel. It also supports hidden waves if your synth is equipped with an OS that supports them on the front panel. It also features a MIDI merge feature so you can run an input from your MIDI interface through the programmer to the synth, inserting the programmer in-line so it doesn't add unnecessarily to your workflow or MIDI rats nest.

I'm still tweaking the firmware to improve the knob layout and I have a new housing version in progress to accomodate a larger OLED display, but the current design is debugged and functional.

The BOM is now available in the Root Directory and the KiCad Directory in csv format.

Housing

My vision for this unit was always been a sidecar that can sit next to the synth on a stand designed for a 76 key workstation and looks like an extension of the synth to the extent possible. Likely, you could design a smaller housing for desktop, as mine is not necessarily designed to minimize its footprint or print time.

The 3D models for the prototype are will be published here in both Fusion 360 and STL formats.

Prototype Version (Adafruit 326 and PCB Mounted MIDI Connections)

For my first build, I used PCB mounted MIDI connectors and a PCB that was optimized for production and shipping cost. This left me with limited space between the knob array and the back panel of the unit for an OLED, so I used an Adafruit 326 0.91 inch display. This was fine for prototyping but in practice in the studio it is really hard to read. Otherwise the knob layout feels good and the overall geometry of the print meets the vision.

I did have some slippage in my printer late in this job (which took 5 days) so there is a bit of a bondo job on this, but it works for a prototype.

In Progress Updgraded Version (Adafruit 2719 and Panel Mounted MIDI Connecitons)

Build two will switch to a 2.42 inch Adafruit 2719 and panel mounted MIDI connections. Design for that enclosure is under way.

Arch Mode (SQ-80 / ESQ-1) Toggle

A panel mounted toggle switch, SW1, facilitates switching between the 32 wave ESQ-1 table and the 75 wave SQ-80 table. In standard mode, this aligns the values sent by the oscillator waveform knobs within the desired range for your model synth. In Glitch Mode, this is more a matter of the mask used for the OLED on parameters 33-75, since all 255 parameters can be transmitted to the synth.

Glitch Mode (Hidden Waveform) and Shift Switch

This momentary pushbutton switch, SW2, has two functions.

A quick tap of this swtich enables glitch mode. This allows knobs 1-3 (oscillator waveforms) to transmit all 255 available parameters to the synth. If you have an OS for your synth that supports hidden waveforms, you will be able to scroll through all 255 paramteters. This only works with the modified OS versions that support hidden waves.

Pressing and holding this switch while also turning a knob makes it function as a shift key, letting you change the MIDI channel on your device or modify up to 63 parameters in your synthesis workflow. Failing to turn a knob while the switch is depressed reverts the programmer to Glitch Mode / Standard Mode.

Potentiometer Layout

Currently, the programmer has been laid out with 32 Potentiometers. You can access up to 63 parameters plus MIDI channel by pressing and holding the Hidden Waveforms button like a shift key.

The knob layout as of version 1.5 is as follows:

GLITCH BUTTON IN THE UP POSITION - NOT PRESSED

GLITCH BUTTON HELD DOWN WHILE TURNING

Software Versions

I recommend Version 1.5 of the firmware for your build if you are building the prototype model with the Adafruit 326. Version 1.6 is a deprecated version I created while debugging. It unnecessarily limits the number of hidden waves available. It turned out that the issue I was trobleshooting was hardware related.

Versions earlier than 1.5 have fewer parameters available on the front panel, and are not fully debugged.

PCB Assembly Notes

Current Working Model

As you might expect, my prototype PCB's have a few boges due to design errors. I did update the designs in KiCad so if you order PCB's with these gerbers, you should not have to boge anyting to build a working model with the Adafruit 326 display. I do have a handful of my prototype PCB's on hand that I'm willing to part with to save you ordering from China, but you will need to install two jumpers and an extra resistor. Reach out if you want one of those.

The OLED is panel mounted. The protruding "ears" on the bottom of the OLED board should be removed prior to installation using a dremel tool or a fine tooth hacksaw blade, because they will interfere with the adjacent pots. A U-channel is printed on the underside of the enclosure lid to hold this edge of the display tight to the lid. The other edge is attached with M2.5 machine screws. Do not over-tighten these screws.

Known Changes In the New Design

The Adafruit 2719 does not have built in I2C Pullup Resistors, so those will beed to be added between the signalling path from the microcontroller to the display. Other changes may be needed, TBD.