MiniJV880: Rompler synth emulation

[probonopd]

https://github.com/giulioz/mini-jv880 - @giulioz has performed a heart surgery and transplanted another synth engine!

MiniJV880 is a rompler-style synthesizer closely modeled on the famous JV-880 by a well-known Japanese manufacturer running on a bare metal Raspberry Pi (without a Linux kernel or operating system).

https://www.youtube.com/watch?v=7LWaYHTNIDI

[probonopd]

Now, wouldn't it be cool if we could multiboot this from the same SD card? Might be possible by using os_prefix in config.txt.

[plamikcho]

Very cool project! Is it compatible with MiniDexed hardware? What about the configs? There is no information in this repo.

[giulioz]

Hey! Author here. So far I developed the thing just to work on my hardware setup, but it should work on other setups with some very minimal changes. I'm trying to find some free time to work on it and I will write some docs soon!

[blixabloxa]

Been playing with this using the nuked sc55 emulator. Would be great to have it co-installed on the minidexed SD card!

[miotislucifugis]

This looks super! I second the request for making hardware configs compatible with minidexed (serial and i2c 1602 displays and assignable GPIOs for the buttons and encoder.) i wouldnt even mind if I had to swap SD cards, but multiboot, whoa!

[plamikcho]

Hi, I made some attempts to get the MiniJV880 working on the same hardware as MiniDexed with the help of the author @giulioz (huge thanks). The code is here: https://github.com/plamikcho/mini-jv880/tree/codespace-humble-goldfish-r79xv4x557hp4jx The good news are that it is working and it is possible to get it running. It requires more buttons (13 more + the rotary encoder button) but the Pi has enough free GPIOs. My changes in @giulioz 's code are quite naive, mostly adapted code from MiniDexed because I do not have experience in C++. The problems I've hit (and cannot solve due to lack of knowledge):

• LCD display is truncated, SSD1306 supports 20 columns but JV880 has 24. My solution is just to cut some of the columns for each row, I've skipped the places with spaces or brackets. This is not optimal and the other menus are broken. To get all of the 24 columns it needs to be rendered by pixels and not chars which requires direct operation with SSD1306 + scaling the JV880 display to 128x32 (this is already done by the author)
• LCD display lacks cursor (SSD1306 issue, in MiniDexed the cursor is not working too). Unfortunately JV880 uses the cursor to cycle through items operated with the rotary encoder. (update, found a way to fix it, now it has a blinking cursor)
• Buttons are not responsive, maybe the debounce time needs some adjustment (or my code has some mistake which I cannot figure out) - this was probably a consequence from the missing cursor and the bad display, now buttons work fine.
• The sound is distorted and has glitches - this probably comes from the multicore adaptation of the emulator for RPi, again no idea how to fix. Recordings are made on RPi3 which performed better (???), RPi4 sound was terrible with distortion and glitches (quite strange for me, I expected the better hardware to work smooth).

JV880 emulator is really cool and sounds really nice, it would be great to run together with MiniDexed (changing the cards or dual boot). I hope that the experienced developers here can help to finish it and to enjoy the sounds on the affordable MiniDexed hardware.
https://audio.com/plamen-dzorev/audio/jv880-test-dowah
https://audio.com/plamen-dzorev/audio/jv880-test-trumpet
https://audio.com/plamen-dzorev/audio/jv880-test-jazzorgan

UPDATE: Again with the help of the author I have some playable patches on RPi4 processing the emulator on a single core. Finally enjoying a nice sounding sax on the MiniDexed :)
https://audio.com/plamen-dzorev/audio/jv880test-turboa
Fixed the buttons and the display cursor. Removed the spinlocks from pcm. First 5-10 mins before the Pi gets hot the patches sound good. Need to add cooling fan.