Runs on the STM32U585 MCU (via Arduino UNO Q) or any Arduino-compatible board. Reads the ENV-1-V0.1 sensor board — BME690 environmental sensor and optional SCD43 CO2 sensor — and outputs structured JSON payloads over serial every 5 minutes.

The daemon (cultivar-daemon) consumes these payloads on the Linux side.

Hardware

ENV-1-V0.1 — dual sensor board designed for the Cultivar appliance.

Sensor	Measures	I2C Address
BME690	Temp, humidity, pressure, gas resistance (10-point sweep)	0x76
SCD43	Real CO2, temp, humidity	0x62 (optional — DNP for colonization)

I2C pins (ESP32S3 dev board — adjust for production):

SDA → GPIO42
SCL → GPIO41

Chamber identity is self-declared: if SCD43 is not detected at init, the board identifies as colonization. If SCD43 is present, it identifies as fruiting. No jumpers, no config — the populated BOM is the configuration.

Library: `cultivar_env`

Wraps the Bosch BME690 SensorAPI directly. No Bosch BSEC2 blob — raw sensor access only.

Installation

Download Bosch BME690 SensorAPI
Copy bme69x.h, bme69x.c, bme69x_defs.h into cultivar_env/src/
Install Sensirion I2C SCD4x via Arduino Library Manager
Install cultivar_env via Sketch → Include Library → Add .ZIP Library

Dependencies

Sensirion I2C SCD4x by Sensirion
Bosch BME690 SensorAPI v1.1.0 (bundled in src/)

Quick start

#include <Wire.h>
#include <cultivar_env.h>

CultivarEnv env;
char jsonBuf[768];
const char* CHAMBER_ID;

void setup() {
    Serial.begin(115200);
    env.begin(Wire, 42, 41);
    CHAMBER_ID = env.scd4x_ok ? "fruiting" : "colonization";
}

void loop() {
    CultivarEnvPayload payload;
    env.collect(payload);

    env.toJSON(payload, jsonBuf, sizeof(jsonBuf));
    Serial.println(jsonBuf);  // → daemon via serial

    delay(300000); // 5 min
}

Gas sweep — 10-point mycology profile

#	Temp°C	Dur ms	Zone	Notes
0	200	150	1 — Baseline	Humidity/CO2 proxy
1	220	150	1 — Baseline	Light alcohols
2	250	150	1 — Baseline	Ethanol
3	280	180	2 — Biological	Acetic acid / bacterial marker
4	300	180	2 — Biological	Terpene zone low
5	320	180	2 — Biological	Geosmin / 1-octen-3-ol
6	340	200	2 — Biological	Aldehyde zone
7	360	200	3 — Heavy	Ammonia / nitrogen
8	380	200	3 — Heavy	Sulfur compounds
9	400	200	3 — Heavy	Heavy VOC fingerprint

Gas resistance values are raw — humidity correction, baseline normalization, and compound inference are handled by cultivar-daemon on the Linux side.

JSON payload format

One payload per collection cycle, emitted as a single newline-terminated JSON line:

{
  "chamber_id": "fruiting",
  "ts": 300000,
  "ambient": {"temp_c": 23.45, "humidity_pct": 82.10, "pressure_hpa": 929.88, "valid": true},
  "co2": {"ppm": 1850, "temp_c": 24.10, "humidity_pct": 83.20, "valid": true},
  "health": {"scd43_present": true, "temp_delta": 0.65, "humidity_delta": 1.10, "temp_ok": true, "humidity_ok": true},
  "baseline": {"established": false, "samples_collected": 3},
  "sweep": [
    {"heater_temp_c": 200, "heater_dur_ms": 150, "zone": 1, "resistance": 85000000, "heater_stable": true, "valid": true},
    {"heater_temp_c": 220, "heater_dur_ms": 150, "zone": 1, "resistance": 72000000, "heater_stable": true, "valid": true},
    {"heater_temp_c": 250, "heater_dur_ms": 150, "zone": 1, "resistance": 61000000, "heater_stable": true, "valid": true},
    {"heater_temp_c": 280, "heater_dur_ms": 180, "zone": 2, "resistance": 420000,   "heater_stable": true, "valid": true},
    {"heater_temp_c": 300, "heater_dur_ms": 180, "zone": 2, "resistance": 280000,   "heater_stable": true, "valid": true},
    {"heater_temp_c": 320, "heater_dur_ms": 180, "zone": 2, "resistance": 195000,   "heater_stable": true, "valid": true},
    {"heater_temp_c": 340, "heater_dur_ms": 200, "zone": 2, "resistance": 148000,   "heater_stable": true, "valid": true},
    {"heater_temp_c": 360, "heater_dur_ms": 200, "zone": 3, "resistance": 102400000,"heater_stable": true, "valid": true},
    {"heater_temp_c": 380, "heater_dur_ms": 200, "zone": 3, "resistance": 102400000,"heater_stable": true, "valid": true},
    {"heater_temp_c": 400, "heater_dur_ms": 200, "zone": 3, "resistance": 102400000,"heater_stable": true, "valid": true}
  ]
}

Collection timing

Production: 5-minute interval — allows full thermal dissipation between heater cycles
Development: 30-second interval — heater self-heating will elevate ambient temp readings
Ambient reading (heater off, 3s settle) runs before each gas sweep

Board setup (Arduino IDE)

Setting	Value
Board	ESP32S3 Dev Module
USB CDC On Boot	Enabled
Flash Size	4MB
PSRAM	OPI PSRAM
Upload Speed	921600

For Arduino UNO Q production deployment: board is STM32U585, Serial1 is used for daemon communication (reserved by Arduino Router — use Serial for debug only).

Notes on BME690 gas sensor

First power-on: allow 15-30 min for gas resistance to stabilize
Full sensor burn-in: ~7 days of cumulative operation per Bosch documentation
102400000 Ω is the clean-air ceiling / saturated sentinel value — valid and expected in clean environments
Resistance values are raw — do not compare absolute values across different units or sessions without normalization

grove5/cultivar-daemon — Linux data pipeline
grove5/cultivar-types — shared types
grove5/cultivar-ui — Svelte frontend
grove5/hardware — schematics, STLs

License

MIT — Grove5
Bosch BME690 SensorAPI: BSD-3-Clause — Bosch Sensortec GmbH

README.md

Cultivar Firmware

What it does