So I watched the video and build details of the black Pill mono synth and always thought it would be better as a simple synth you can play. So I picked up this Axiom 25 for next to nothing and just gutted it down to the internal midi board, all encoders and buttons have been disconnected except for the transpose.
The plan is build the blue Pill synth and add the hardware editor and construct it all in this neat little case.
Bonus is the Axiom has aftertouch as well so it’s perfect for a little synth. Can still use it as a controller as my controller will output CC messages.
Suffering massively from allergies, usual for me from August to September and the workshop is like a furnace and the air con makes it worse, but today I found a pill that finally seems to help and it’s white, not blue like the ones I’ve been taking for the past 5 days, so I got more wiring finished.
I had some issues with using an external SD card with the Teensy 4.0, but I managed to replace the Arduino SD card adaptor with a Teensy Rev D sound card that has an onboard SD card socket and jerry rigged that into place and it works perfectly with the main display on the same SPI bus.
I’m actually 4 digital pins short and these are used for the save, menu, back, recall and need to support long pushes, so I have two choices, add them to the MCP chips and work out how to do long pushes on them or connect to the 10 pins under the Teensy 4.0 to give me the additional required digital pins.
I prefer the first method as it will be tidier, but the second method is simpler.
I haven’t written that yet, but the 7 i2c displays are connected to an 8 way i2c mux and I will be able to address and update them individually. I used the same method as the XVA1 editor that used 8 displays plus a main spi display.
The Black Pill Synth
Hardware completed, power supply and synth module installed into the case. I had a few issues connecting the USB out of the axiom to the USB host of the Teensy 4.0. It worked, but cut out after 16 to 100 notes of playing. Couldn’t figure it out so added an extra DIN input to the editor so it could receive the Axiom on a separate midi input whilst also having a midi input as normal.
Also the schematics for the BP synth are missing some ground and +ve connections to the sound card, you get no sound if you follow the schematics, but having just used 12 of the same sound cards in my last synth I knew it needed pins strapped high and low. Then it all worked perfectly.
I also managed to destroy one of the 0.96" displays today, top left , I was using a screwdriver to prise off the film and caught it badly, my only spare was a slightly different brand and the displays although cyan,don’t match. My OCD will want to fix that eventually.
I will make a video tomorrow, my eyes are super bloodshot with allergies and I can hardly see to type.
A link to the code, a schematic will be posted shortly to go with it. But those of you who are code savvy can probably work out the wiring just from the pin assignments.
