🌧️ ESP32 Rainfall Sensor (Tipping Bucket + MQTT)

A robust, Wi-Fi-connected ESP32 rainfall monitor based on the DFRobot SEN0575 tipping-bucket rain gauge.
The project measures rainfall accurately, handles Wi-Fi reconnects and DST automatically, and publishes live and hourly rainfall data to an MQTT broker for visualization (Home Assistant, Node-RED, Grafana, etc.).

⚠️ Project status: This project is currently in the testing and calibration phase.
Hardware and software are functional, but behavior under long-term outdoor conditions and MQTT performance are still being validated.
Contributions and feedback are welcome!

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📦 Features

✅ Accurate rainfall measurement

• Uses DFRobot SEN0575 tipping-bucket rain gauge (reed switch output).
• Detects every tip via an interrupt on ESP32 GPIO.
• Each tip equals a configurable rainfall volume (default 0.28 mm).

✅ Time-aware data logging

• Uses ESP32 SNTP with automatic CET/CEST DST correction.
• Keeps a rolling log of 7 days × 24 hours rainfall totals.

✅ MQTT integration

• test/rainfall/impulse → Real-time impulses with current-hour total.
• test/rainfall/hourly → Retained 7-day snapshot with all hourly values.
• Messages use the most reliable delivery supported by PubSubClient.

✅ Offline recovery

• Continues counting rainfall while offline.
• Sends all accumulated data once Wi-Fi or MQTT reconnects.

✅ Resilient Wi-Fi

• Automatically switches between primary and backup SSID.
• Detects stuck connection attempts and resets the interface.

✅ OTA updates

• Used ElegantOTA library

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🧰 Hardware

Component	Model / Description	Connection
ESP32 DevKit	ESP-WROOM-32 or WROVER module	Main controller
Rain gauge	DFRobot SEN0575 tipping-bucket sensor	Signal → GPIO27, GND → GND
Power	5 V USB or regulated 5 V supply	via ESP32 Vin/USB

🧩 SEN0575 notes

• Output is a simple reed switch (digital on/off).
• Internal magnet closes contact once per bucket tip (≈ 0.28 mm of rain).
• ESP32 pin uses INPUT_PULLUP, so no external resistor is required.
• Ensure the cable and junctions are weatherproof for outdoor use.

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⚙️ MQTT Topics & Payloads

🔹 test/rainfall/impulse

Real-time message on every tip:

{
  "volume": 0.28,
  "hour_total": 1.40,
  "time": "2025-11-23T21:43:02"
}

🔹 test/rainfall/hourly

{
  "2025-10-17": [
    {
      "00:59:59": "0",
      "01:59:59": "0",
      "02:59:59": "0",
      "03:59:59": "0",
      "04:59:59": "0",
      "05:59:59": "10",
      "06:59:59": "15",
      "07:59:59": "5",
      "08:59:59": "0",
      "09:59:59": "0",
      "10:59:59": "0",
      "11:59:59": "0",
      "12:59:59": "0",
      "13:59:59": "0",
      "14:59:59": "0",
      "15:59:59": "0",
      "16:59:59": "0",
      "17:59:59": "5",
      "18:59:59": "10",
      "19:59:59": "0",
      "20:59:59": "0",
      "21:59:59": "0",
      "22:59:59": "0",
      "23:59:59": "0"
    }
  ],
  "2025-10-18": [
    {
      "00:59:59": "0",
      "01:59:59": "0",
      "02:59:59": "0",
      "03:59:59": "0",
      "04:59:59": "0",
      "05:59:59": "10",
      "06:59:59": "15",
      "07:59:59": "5",
      "08:59:59": "0",
      "09:59:59": "0",
      "10:59:59": "0",
      "11:59:59": "0"
    }
  ]
}