Hardware Build Configs.
Hardware Build Configs
Practical sensor builds for growers, on commodity hardware (ESP32, ESPHome, Tasmota). Each one lists the real parts with prices, the firmware, the time it takes, and what to watch out for. Most land under $100.
About these builds
Open Agriculture Technology positions for commodity sensors and small-to-medium growers using the open IoT ecosystem (Home Assistant, ESPHome, Tasmota, MQTT). The configs below are practical builds you can complete in a weekend with under $100 in parts.
All build configs 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.
A few of these (cold chain, greenhouse monitoring) also have a deeper reference version, a different route to the same need, in Build → Configs: a full bill of materials and a ready-to-flash sketch instead of a wired ESPHome build.
Common parts library
| Part | Purpose | Typical $ |
|---|---|---|
| ESP32 dev board | Wi-Fi 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 configs 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 Open Agriculture Technology's broker in 5 lines of config
- OTA firmware updates over Wi-Fi (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 "Open Agriculture Technology Hardware Build Configs (openagriculturetechnology.com)". Firmware references: ESPHome (esphome.io, MIT), Tasmota (tasmota.github.io, GPL), Home Assistant (home-assistant.io, Apache 2.0).