Hardware Build Recipes.
Hardware Build Recipes
DIY sensor build recipes for growers. ESP32, Tasmota, ESPHome — commodity hardware. Under $100 typical.
About these builds
OAT positions for commodity sensors and small-to-medium growers using the open IoT ecosystem (Home Assistant, ESPHome, Tasmota, MQTT). The recipes below are practical builds you can complete in a weekend with under $100 in parts.
All build recipes are CC BY 4.0. The firmware is open source (ESPHome / Tasmota are GPL/Apache). The hardware is commodity from Amazon, AliExpress, Adafruit, SparkFun. Nothing is OAT-proprietary.
Common parts library
| Part | Purpose | Typical $ |
|---|---|---|
| ESP32 dev board | WiFi microcontroller; the brain of most builds | $5-12 |
| ESP32-S3 | More powerful + camera-capable variant | $10-15 |
| BME280 | Temp + humidity + barometric pressure (I2C) | $3-8 |
| SCD40 / SCD41 | True NDIR CO₂ sensor; the gold standard | $45-65 |
| DS18B20 | Waterproof temp probe; 1-wire | $2-5 |
| DHT22 / AM2302 | Temp + humidity; cheaper than BME280, less accurate | $3-6 |
| Govee H5074/H5075 | BLE temp/humidity sensors; sub-$15 each; outdoor capable | $10-15 each |
| Atlas Scientific kits | Lab-grade pH, EC, DO probes for hydroponic | $60-150 per param |
| HX711 + load cell | Weight measurement (beehive, plant scale) | $5-15 |
| SIM7000G LTE-M module | Cellular for outdoor/remote sites | $25-40 |
| Solar panel + 18650 + charge controller | Off-grid power for remote builds | $15-30 |
| JST connectors + wires | Clean wiring | $5-10 |
| 3D-printed enclosure (PETG) | Outdoor-rated housing | $2-5 in filament |
Why ESPHome over raw Arduino
Most recipes here use ESPHome as the firmware. ESPHome is a YAML-defined framework that compiles to ESP32/ESP8266 firmware, with built-in support for most sensors, OTA updates, MQTT or Home Assistant native integration, and a clean web UI. Compared to writing raw Arduino code:
- YAML config (no C++ programming required)
- Built-in MQTT client publishes to OAT's broker in 5 lines of config
- OTA firmware updates over WiFi (no plug-in to flash again)
- Sensor library covers 200+ devices out of the box
- Active community; problems are usually already solved
Tasmota is a similar alternative for some sensors. Tasmota is more "appliance-like" (flash and configure via web UI); ESPHome is more "code-like" (YAML config, more flexibility). Either works.
Free under CC BY 4.0. Cite as "OAT Hardware Build Recipes (openagriculturetechnology.com)". Firmware references: ESPHome (esphome.io, MIT), Tasmota (tasmota.github.io, GPL), Home Assistant (home-assistant.io, Apache 2.0).