In this project I wanted to control a Roland Super JX-10 with an editor, but I didn't want two displays and duplicated controls. The JX-10 and MKS-70 have an internal assigner board, it's the heart of the synth, it basically controls every aspect of the synth, midi, front panel controls, screen management, patch management, keyboard input, aftertouch and all rear panel connections for pedals etc. This is typical in synth design where the main board controls voice boards.
The unusual thing about the JX voice board is that they are fully self contained 6 note synthesisers that only require power, an 8mhz clock and serial data to produce any sound.
So with some help from Fred Vecoven and watching a YouTube video where a guy wrote a VST to control his MKS-70 over serial I decided I could replace the whole assigner board with just a Teensy 4.1 and some logic/midi chips.
This did two things, it removed the requirement for two screens and also I could remove unwanted buttons and encoders and keep the interface simple.
But it also meant that I had to replicate all the functions of the Roland assigner including the arpeggiator, chase play, patch management, key modes and assignments for upper and lower patches, plus read pedals and CV inputs, manage the mux and buttons/LEDs and midi.
Km quite happy with the results so far, I have a fully editable JX-10 that can receive standard patch and tone dumps over sysex, arpeggiator, chase play etc all work as they should. The design uses all 3 i2c channels, one for the display and two for the buttons and LEDs, the pots and sliders are read on a 64 channel mux with 8 bit resolution. The values of the JX never exceed 99, so an 8 bit resolution is fine.
The voice cards were upgraded to Vecoven V4, a new switch mode PSU was used to save space and an OLED was used for the main display. It was all housed in a CME UF-70 case which was gutted except for the midi board.
The unusual thing about the JX voice board is that they are fully self contained 6 note synthesisers that only require power, an 8mhz clock and serial data to produce any sound.
So with some help from Fred Vecoven and watching a YouTube video where a guy wrote a VST to control his MKS-70 over serial I decided I could replace the whole assigner board with just a Teensy 4.1 and some logic/midi chips.
This did two things, it removed the requirement for two screens and also I could remove unwanted buttons and encoders and keep the interface simple.
But it also meant that I had to replicate all the functions of the Roland assigner including the arpeggiator, chase play, patch management, key modes and assignments for upper and lower patches, plus read pedals and CV inputs, manage the mux and buttons/LEDs and midi.
Km quite happy with the results so far, I have a fully editable JX-10 that can receive standard patch and tone dumps over sysex, arpeggiator, chase play etc all work as they should. The design uses all 3 i2c channels, one for the display and two for the buttons and LEDs, the pots and sliders are read on a 64 channel mux with 8 bit resolution. The values of the JX never exceed 99, so an 8 bit resolution is fine.
The voice cards were upgraded to Vecoven V4, a new switch mode PSU was used to save space and an OLED was used for the main display. It was all housed in a CME UF-70 case which was gutted except for the midi board.
