Solar-powered Smart Plant Care System with Atom S3 Lite

🧭 TL;DRA

fully autonomous plant care device powered only by solar energy.Uses M5Stack Atom S3 Lite and multiple sensors to measure environment & soil moisture, running solely on solar + battery.Sends telemetry via UDP to a Raspberry Pi server and automatically waters when moisture drops below threshold.“Solar × IoT — stay connected to your plants.”

🎯 Background & PurposeI

often forgot to water my plants, especially with irregular schedules.To solve this, I built a self-sustaining, outdoor-capable plant care system requiring no mains power.

Although I work as an embedded software engineer for residential fuel cells, I’m still early in my career. This project was a way to gain practical, hands-on embedded development experience while applying my knowledge in low-power design, sensor processing, and power management.

🧩 Hardware

• M5Stack Atom S3 Lite
• Unit Watering (pump + soil moisture sensor)
• Grove BME280 (temperature, humidity, pressure)
• Grove Light Sensor (lux)
• Grove INA219 (voltage/current monitor)
• ExtPortForAtom
• Waveshare SPM D (solar charging)
• 18650 Li-ion battery + holder
• 1000µF capacitor (5V output smoothing)
• 12V/10W solar panel
• Waterproof case (80×160×55mm)

🗺️ System Diagram

Text Ver（more detailed）

[Sun]
  |_
    |
    v
[12V/10W Solar Panel]
          |
    [SPM D Module]---[18650 Battery]
          |5V
    +-----+----+
    | 1000µF   |
    v          v
[Atom S3 Lite]--(ExtPort)-->[BME280 Sensor]
   |     \--(PortB)-->[Unit Watering + Soil Moisture]
   |     \--(PortD)-->[Light Sensor]
   |--(I2C)-->[INA219 Power Monitor]
   |--(softAP)-->[Provisioning Server]
   |
   | WiFi UDP (10min interval)
   v
[Raspberry Pi 4B Server]
   |--(UDP Receive)-->[Data Logging]
   |--(Flask WebUI)-->[Dashboard & Remote Config]

💻 Software

① Atom S3 Lite

• Dev Env: PlatformIO + VSCode
• Lang: Arduino (C++)
• Sensors: BME280, Light sensor, INA219, Unit Watering
• Comms: UDP every 10 minutes
• Control: Auto-pump if moisture < threshold
• Power Saving: Deep Sleep for multi-day runtime
• Remote Provisioning: SoftAP to set thresholds, SSID/PASS from server, stored in NVS

② Raspberry Pi 4B

• Lang: Python
• Functions: UDP receive → parse → log, Flask + Plotly + Bootstrap dashboard, remote config
• Usage Example:
• Lower threshold in dry weather to shorten drought time
• View sensor data in real time from dashboard

📊 Results

• Accurate sensor data collection and transmission

• Verified soil-moisture-based automatic pump control

• Daytime solar charging, nighttime battery operation

When power is supplied from the solar panel, the lithium-ion battery is charged. At that time, the INA219 connected in series to the lithium-ion battery shows a negative current value.

🗺️ Next Steps

• TinyML for predictive irrigation
• Scheduling based on weather and history
• Enhanced long-term data logging & visualization

🙌 Thoughts

Even as a software-focused engineer, M5Stack + Grove lowered the barrier to hardware.