RED SEA

A weather-driven algorithmic MIDI sequencer & CC beatmasher, built on a single ESP32-C3

For help/questions email me: cirocular@gmail.com
Github: https://github.com/Cirocular-Vlasenko-Daniil/Red-Sea
ESPidi project: https://github.com/EugeneCarlo/ESPidi

Four OLED pages, one encoder, four buttons, and underneath it all, four algorithmic "weather" engines that never repeat a pattern quite the same way twice. Point it at a synth, hook up a MIDI clock, and let it rain.

RED SEA sits between a MIDI clock source and connected gear. It generates Control Change modulation across four assignable CC parameters and drives a 16-step note/CC sequencer, both controlled by one of four selectable algorithmic engines:

• FOG — Morphing LFO engine (sine, triangle, or square). The SHAPE parameter changes the waveform itself rather than just skewing it: on sine it adds harmonics, or in the other direction clips the signal and adds noise; on triangle it shifts continuously toward a rising or falling sawtooth.
• SUN — refraction delay engine. When a parameter's value would exceed its range, it triggers a series of echo repeats instead of simply clamping, each one landing at half the previous interval. If a sequencer note fires on the same tick the echo series starts, the echoes also retrigger that note, transposed further with each repeat.
• RAIN — stochastic modulation engine. The four parameters can drift out of sync with the shared clock independently, occasionally affect a neighboring parameter, and be interrupted by randomized events that force a parameter to its minimum or maximum.
• SNOW — euclidian based random freezer. Mutation triggered by a Euclidean rhythm instead of a fixed interval. Each hit can also freeze or unfreeze any parameter on the device, including the engine's own parameters.

Features

• Four algorithmic engines (FOG / SUN / RAIN / SNOW), each with four dedicated parameters
• 16-step sequencer (note, CC, a third assignable destination, per-step retrigger) with external or internal clock
• Performance BYPASS and FREEZE modes, engaged on button press
• MIDI Learn: captures a CC number from the next incoming Control Change message
• Per-parameter freeze, independent of the global performance modes
• Settings are written to flash and persist across power cycles

Hardware

This firmware was developed for the ESPidi hardware platform, designed by Eugene Carlo. It doesn't require that specific board, though — anyone can build a compatible device by wiring an ESP32-C3, an SSD1306 128×32 OLED, a rotary encoder, and three buttons according to the pinout below. You can build your own platform with same spec and go on.

MCU	ESP32-C3
Display	SSD1306 128×32 OLED, I²C
Input	1× rotary encoder w/ push button, 3× tactile buttons (PLAY / TAP / PAGE)
MIDI	Standard 31250 baud DIN in/out over UART
Power	USB-C

See MANUAL.md for the full pin-out, control gestures, and a page-by-page parameter reference.

Building & flashing

The firmware is a single .cpp translation unit (not an .ino sketch), written for the Arduino core on ESP32. Build with PlatformIO or the Arduino IDE configured for an ESP32-C3 board. Dependencies: Adafruit_GFX, Adafruit_SSD1306, Preferences (bundled with the ESP32 core).

Wiring reference (see Pins:: in the source for the authoritative list):

Signal	GPIO
PLAY	1
TAP	2
PAGE	3
Encoder switch	4
Encoder A / B	5 / 6
MIDI RX / TX	7 / 10
OLED SDA / SCL	8 / 9

Status

Released — first stable version. Issues and pull requests welcome.

License

Firmware source code is licensed under the MIT License.

Documentation (this file, the manual, and their Russian translations) is licensed under CC BY 4.0.

Credits

• Firmware: Daniil Vlasenko
• ESPidi hardware platform: Eugene Carlo