CS-1

A CS-80-style synthesizer firmware for the M-VAVE FM-1: a sound module for a dawless rig, played over MIDI (TRS or USB) from a sequencer such as the Novation Circuit Tracks.

CS-1 is a Yamaha CS-80 in spirit: eight voices of two channels each (I and II), every channel a VCO (sawtooth and / or pulse with PWM, noise), a resonant high-pass and low-pass filter in series, a sine added after the filters, a filter envelope (IL, AL, A, D, R), a VCA envelope (A, D, S, R) and the touch response (velocity and pressure to brilliance and level); a sub oscillator to pitch, filter and level; the ring modulator; the chorus / tremolo (stereo here); portamento and glissando, channel II detune, the initial pitch bend, keyboard control, sustain modes I and II, brilliance and resonance levers, and the SELECT encoder as the ribbon. For a sequencer with no hands: an auto after touch curve each note plays by itself, MIDI learn, a CC map for the Circuit Tracks' macros, and clock sync. Effects beyond the instrument: drive and two shelves, a flanger, a stereo delay with a tape character, a phaser, and a Dattorro plate reverb with a shimmer at any interval. The 22 preset tones come from the owner's manual's charts (tools/gen_presets.py says how they were read and mapped), and the voice was calibrated against a CS-80 emulation, one dry note at a time (tools/compare_wav.py). 52 sounds, 32 user presets, a documentation site with the firmware running in the browser, and an installer in the browser.

What it stands on

• Dinghy (zvenson): the minimal FM-1 firmware template, which is the Felucca / SLOOP platform (Leo Kuroshita, Hügelton Instruments; isod89).
• FM-106 (PatttF): the second core as an audio worker (firmware/hal/fm1_multicore.h, firmware/src/audio_worker.h) and MIDI IN on the TRS jack (midi_uart.c), ported onto the Dinghy tree here.

Everything is GPL-3.0-only; see LICENSING.md.

MIDI clock from the sequencer drives the delay's SYNC divisions (DELAY page) and the sub oscillator's (SUB OSC 2); VINTAGE on PERFORM lets each voice drift a few cents on its own, as the voice cards did.

The sounds

PRESETS (and program change) runs through these, then the 32 user slots; HOME + a key picks a tone for a channel, ALGO picks a category on HOME (PAD, STRINGS, BRASS, KEYS, BELLS, BASS, LEAD, FX, USER) for PRESETS to browse, and turns a button's pages elsewhere. The classic ones are recipes after what is documented about the records (which presets, the technique), not transcriptions; they pair a row I tone with a row II tone as the instrument does, and most carry the chorus, a touch of detune, an auto after touch curve and the plate. The last group is converted from CS-80 V factory presets on a computer with the plugin installed: tools/converted.txt lists them with our names, tools/arturia_convert.py reads each preset's panel and maps it through the same calibration as the manual's tones (tools/converted.json keeps the values, so the build does not need the plugin), and tools/level_converted.py evens out their loudness by measurement.

Layout

Build and run on a computer

pip3 install Pillow
tests/run_host.sh          # -> build/host/cs1.wav, build/host/cs1-*.png

On macOS without the Xcode licence accepted, point the compiler at the Command Line Tools: DEVELOPER_DIR=/Library/Developer/CommandLineTools tests/run_host.sh.

Play it in the browser, and the site

The firmware runs in an AudioWorklet against a fake FM-1, with the panel on the page and Web MIDI in and out (Chrome or Edge). The documentation site wraps it: the pages in web/site/, a reference that tools/gen_docs.py generates from the firmware's own page and sound tables, and the emulator under emu/. Needs Emscripten (tools/get_emsdk.sh installs it into ~/.emsdk, no Xcode or Homebrew) and Node for the test:

web/site/build.sh                # -> build/site/ (index, manual, sound, reference, img/, emu/)
node web/emu/emu_test.mjs        # the wasm in Node: boots, sounds, LEDs, MIDI, settings, determinism, cost
python3 tools/serve_web.py       # http://localhost:8000/  (the emulator at /emu/; Web MIDI needs localhost or https)

Click Switch on, then play the keys (mouse, touch, or the Q and A rows), turn the knobs (drag or wheel), and pick your MIDI interface under MIDI in to play it from a sequencer. CC 80 to 87 and MIDI learn (REC) map a controller's knobs, as on the FM-1. emu/?sound=N opens a sound, which the site's "Try" links use. The settings sector and the user bank are kept in the browser's localStorage; Export presets writes the bank to a .cs1bank file. What the emulator cannot tell you: CPU cost on the real chip, the dual-core split, USB audio and the updater.

tests/run_tests.sh runs the host build, the site build and the emulator test together. build/site/ is the whole site, ready for any static host (GitHub Pages included).

Build for the FM-1

Needs the JieLi toolchain (tools/get_toolchain.sh), the AC79 SDK checkout, and Docker on macOS:

./build.sh                 # -> build/cs1.fwsc  (DINGHY_DUAL_CORE=0 ./build.sh for single-core)
python3 tools/fm1_install.py build/cs1.fwsc

The package identity is FM-1_95N (N = minor version). Installing any custom firmware is at your own risk: hold OCT- at power-on for the USB rescue; M-VAVE's updater or the Firmware Hub's "Back to official V15" takes you back to stock, and any firmware with Felucca's or M-VAVE's update loader installs over CS-1 (from 0.3.2; before, the official package was refused on a unit with an older flash head). tests/ota_test.c runs the update entry on a computer against a package. tools/arminator_read.py and tools/arturia_convert.py --all read whole preset libraries (Arminator 2's banks via tests/vstdump.c under Wine, the CS-80 V's) into a corpus; tools/gen_random.py reduces the 910 sounds to the RANDOM page's model (a mean a category and twelve directions, firmware/gen/cs1_random.h); nothing of the libraries themselves is shipped.