Bill of Materials — Dev Platform
One complete dev platform unit. All components are off-the-shelf modules — no custom PCB fabrication required.
Amazon fallback sourcing
If you are not buying through the Plant Caravan BOM, use Amazon for speed and treat AliExpress as the canonical reference for the general form factor and price target. Do not match on marketing copy alone — verify the electrical interface and footprint.
| Component | Amazon search | Verify before buying |
|---|---|---|
| ESP32-C3 Supermini | ESP32-C3 SuperMini | USB-C board, ESP32-C3, male headers or headers included |
| ESP32-C3 carrier board | ESP32-C3 Supermini expansion board | Female socket for the Supermini, 3-pin servo-style breakouts, JST battery connector |
| SCD41 breakout | SCD41 breakout | SCD41, not SCD30; 3.3V I2C breakout |
| BH1750 breakout | BH1750 breakout | BH1750 ambient light breakout with SDA/SCL/VCC/GND pins |
| BME280 breakout | BME280 breakout 3.3V | BME280, not BMP280; exposes temperature, humidity, and pressure |
| Capacitive soil probe | capacitive soil moisture sensor v1.2 | Analog AOUT/VCC/GND probe; avoid resistive fork-style probes |
| Dupont jumper kit | female to female dupont jumper wires | Female-female jumpers for the I2C splitter and soil wiring |
Common wrong substitutions
- BMP280 instead of BME280: pressure + temperature only, no humidity.
- SCD30 instead of SCD41: different module size, different power and mechanical assumptions.
- ESP32-S2/S3 boards instead of ESP32-C3 Supermini: wrong footprint for the carrier board.
- Resistive soil probes: corrode quickly and are not the intended sensor for this platform.
- 5V-only sensor boards: the dev platform wiring assumes 3.3V sensor power.
Motherboard + MCU
| Component | Part | Qty | Est. Cost | Source | Notes |
|---|---|---|---|---|---|
| Carrier board | ESP32-C3 Supermini servo-style carrier | 1 | $3–5 | AliExpress | Servo 3-pin breakout (GND/VCC/Signal), battery connector, 5V/GND/3.3V top rail |
| MCU | ESP32-C3 Supermini | 1 | $2–3 | AliExpress / Amazon | Male header pins, seats into carrier board |
Sensors
| Component | Part | Qty | Est. Cost | Source | Notes |
|---|---|---|---|---|---|
| CO2 + temp + humidity | SCD41 breakout module | 1 | $12–15 | AliExpress | I2C @0x62, connects via I2C splitter |
| Light | BH1750 breakout module | 1 | $2–3 | AliExpress | I2C @0x23, connects via I2C splitter |
| Temp + humidity + pressure | BME280 breakout module | 1 | $2–3 | AliExpress | I2C @0x76, connects via I2C splitter |
| Soil moisture | Capacitive v1.2 probe | 1–3 | $1.30 ea | AliExpress | Analog 0–3.3V, JST-PH connector |
Cables + Connectors
| Component | Part | Qty | Est. Cost | Source | Notes |
|---|---|---|---|---|---|
| Dupont jumper wires (F-F) | Assorted colors | 1 kit | $2–3 | AliExpress | For I2C Y-splitter and soil probe connections |
I2C Y-Splitter Cable (DIY)
Make a 4-wire Y-splitter to connect multiple I2C sensors in parallel:
- Splice 2+ female dupont ends onto each of 4 wires (SDA, SCL, VCC, GND)
- One end connects to carrier (GPIO4, GPIO5, 3.3V, GND)
- Branch ends connect to each I2C sensor (SCD41, BH1750, etc.)
Soil Probe Cables
Each soil probe has 3 wires (AOUT, VCC, GND) that connect directly to carrier servo groups — no splitter needed.
Future / Optional
| Component | Part | Qty | Est. Cost | Source | Notes |
|---|---|---|---|---|---|
| Relay module | 3.3V 1-channel relay (optocoupler isolated) | 1 | $2–3 | AliExpress | Active-low, for pump/light control via GPIO6 |
| I2C hub board | 4-way I2C splitter breakout | 1 | $1–2 | AliExpress | Cleaner than DIY Y-splitter cable |
Tools Required
- Soldering iron (for custom I2C cable lengths, optional)
- USB-C cable (power + flashing)
- Computer with ESPHome dashboard or CLI
Per-Unit Cost Estimate
| Config | Components | Est. Cost |
|---|---|---|
| Minimal (1 soil probe) | ESP32 + carrier + SCD41 + BH1750 + 1 soil + wires | ~$22–28 |
| Full (3 soil probes) | ESP32 + carrier + SCD41 + BH1750 + BME280 + 3 soil + wires | ~$27–34 |
Prototype cost is higher than production BOM due to breakout module markup. Production uses bare ICs on custom PCB with integrated I2C bus.