OX Platform
The OX platform is the Outdoor Solar variant of Plant Caravan's ESP32 sensor platform.
It uses the same core ESP32-C3 sensor stack as the rest of the modular platform, but packages it for outdoor deployment with:
- solar charging
- a rechargeable LiPo battery
- deep-sleep operation
- a weather-resistant enclosure
- outdoor mounting hardware
In current Plant Caravan naming, OX means Outdoor Solar.
What OX is
OX is the path for deployments where the sensor lives outside near plants, beds, containers, or railings and needs to run for long periods without a fixed USB power source.
The intended architecture is:
- MCU: ESP32-C3
- Power: solar panel + LiPo battery, with USB fallback
- Network: WiFi 2.4GHz
- Sensor stack: the shared Plant Caravan environmental and soil sensors
- Telemetry model: wake, read, publish, sleep
This is not a separate BLE product line. BLE beacon exploration is currently deferred and should not be treated as the active OX platform direction.
Core hardware
OX builds on the modular sensor platform requirements and keeps the same ESP32-centered architecture.
| Layer | Current direction |
|---|---|
| Compute | ESP32-C3 |
| Power | 3.7V LiPo charged from a 0.5-1W solar panel |
| Fallback power | USB |
| Sensors | Shared Plant Caravan stack from the modular platform |
| Enclosure | IP65-or-better outdoor enclosure |
| Mounting | Stake, clamp/bracket, and adjustable solar mounting |
Sensor scope
The outdoor platform is intended to stay compatible with the shared sensor stack from the modular platform:
| Sensor | Purpose |
|---|---|
| SCD41 | CO2, temperature, humidity |
| BH1750 | Light / lux |
| Capacitive soil probes | Soil moisture |
That compatibility is explicit in the requirements: the outdoor module extends the shared core platform rather than replacing it.
Power model
OX is designed around solar charging and deep sleep.
Requirements direction
- solar input through the expansion board charge path
- minimum 250 mAh LiPo battery
- default 5-minute wake interval
- target wake cycle under 3 seconds
- target deep-sleep current below 500 uA, with a long-term target below 50 uA
- survive 72+ hours without solar input
Current sizing study
The current battery/solar analysis recommends a compact baseline:
| Component | Current recommendation | Why |
|---|---|---|
| Battery | 250 mAh LiPo | Small enclosure fit, 6+ days without sun |
| Solar panel | ~0.44-0.5W panel | Roughly 2.9x daily energy headroom at the modeled load |
At the modeled 5-minute wake interval, the analysis estimates:
- about 31.4 mAh/day consumption
- about 6.4 days of battery-only runtime on a 250 mAh cell
Outdoor-specific requirements
The OX platform is defined by the outdoor module requirements in REQ-006.
Environmental protection
- enclosure target: IP65 or better
- UV-resistant materials
- sealed cable penetrations
- breathable membrane vent for CO2 exchange
- conformal coating for condensation resistance
Mounting
- stake mount for soil deployment
- clamp/bracket option for railings or bed edges
- adjustable solar-panel angle
- preferred separation between sensor location and panel location when needed
Temperature and durability
- operating target: -10C to 50C
- battery-safe charging constraints
- corrosion-resistant outdoor hardware
- multi-season deployment expectations
Firmware direction
The intended OX firmware behavior is different from the always-on indoor dev platform:
- wake from deep sleep
- power sensors
- read measurements
- publish telemetry
- return to sleep
The requirements call for a message-based telemetry path compatible with deep sleep. For the outdoor variant, the spec points toward MQTT rather than a continuously connected Home Assistant API session.
Current implementation status
The OX platform is specified and partially de-risked, but it is not implemented end-to-end on main yet.
What exists now
- outdoor requirements in
specs/REQ-006-outdoor-solar-module.md - shared platform requirements in
specs/REQ-003-modular-sensor-platform.md - battery and solar sizing study in
hardware/outdoor/battery-solar-analysis.md - reusable battery wiring and monitoring guidance in the dev-platform assembly docs
What is not finished yet
- committed outdoor-specific ESPHome variant overlay
- committed deep-sleep + outdoor publish path
- finished weatherproof enclosure and solar mount
- published outdoor deployment runbook
Important current limitation
The committed hardware/firmware/plant-monitor.yaml is still the general ESP32 dev-platform firmware. It exposes Home Assistant API, web server, and Prometheus, but it is not yet the finalized outdoor OX firmware variant.
Relationship to other platform paths
| Platform | Best fit |
|---|---|
| Indoor Monitor / Seedling Platform | USB-powered indoor deployments |
| OX Platform | Outdoor, solar-powered ESP32 deployment |
| BLE beacon exploration | Deferred for now; not the active OX definition |
Source material
This doc is based on the current OX definition in:
AGENTS.mddevice model codesspecs/REQ-003-modular-sensor-platform.mdspecs/REQ-006-outdoor-solar-module.mdhardware/outdoor/battery-solar-analysis.mdhardware/firmware/plant-monitor.yaml