Users Guide of Pool Monitor

Setup

When the device is powered on for the first time (or after a factory reset), it starts a WiFi hotspot named pool-monitor.

1. Connect your smartphone or laptop to the pool-monitor WiFi network (open, no password).
2. A captive portal should open automatically. If not, open a browser and go to http://192.168.4.1.
3. Enter the following:
   • WiFi SSID and password
   • MQTT broker hostname or IP address
   • MQTT port (default: 1883)
4. Click Save — the device reboots and connects to your network.

After a few seconds, the E-Ink display updates with the current pool data.

MQTT Broker

The Pool Monitor reads data published by the Pool Controller via Home Assistant MQTT state topics. Your MQTT broker must be reachable from the same WiFi network as the monitor.

Display Layout

The E-Ink display shows the following information:

┌──────────────────────────────────┐
│ 🌊  Pool Temperature    25.3 °C │
│ ☀️  Solar Temperature   55.1 °C │
│                                  │
│ ⏱️  Pump Pool           ON      │
│ ⏱️  Solar Pump          ON      │
│ ⏱️  Mode                auto    │
│                                  │
│         14:30                    │
│    www.smart-swimmingpool.com    │
└──────────────────────────────────┘

• Temperatures are updated whenever new MQTT data arrives.
• Pump status shows ON / OFF based on the pool controller state.
• Mode shows the current operation mode (auto, manual, etc.).
• Time is synchronised via NTP (hourly) with automatic CET/CEST.
• Branding at the bottom shows the project website.

The display only updates when data changes — it stays unchanged during deep sleep to save energy.

Network Configuration (mDNS)

The device is reachable on your local network as pool-monitor.local via mDNS. This works on most networks without any configuration.

The DHCP lease is preserved across deep sleep cycles — the device does not release its IP address when going to sleep. It remains visible in the router’s client table (though unreachable while sleeping).

MQTT Errors and Configuration Portal

If the MQTT broker cannot be reached (wrong hostname, temporary outage, etc.), the device automatically starts a configuration portal:

1. The display shows:
   • WiFi SSID (pool-monitor)
   • Access point IP (192.168.4.1)
   • A QR code for quick access
2. Connect to the pool-monitor WiFi network (open, no password).
3. Open the configuration page — either scan the QR code or go to http://192.168.4.1.
4. Correct the MQTT settings (hostname, port) or WiFi credentials.
5. Click Save — the device reboots and retries the connection.

DNS tip: If the MQTT hostname (e.g. smarthome-pi) cannot be resolved, enter the IP address instead. The hostname is still attempted without DNS (PubSubClient resolves internally), but a direct IP is more reliable.

The portal stays active for 5 minutes. If no configuration is saved within this time, the device enters deep sleep to conserve power. It retries the connection on the next wake cycle (every 180 seconds).

OTA Firmware Updates

The Pool Monitor supports over-the-air (OTA) firmware updates via GitHub Releases:

• On each wake cycle, the device checks GitHub for a newer firmware version.
• If an update is available, it downloads the .bin release asset and flashes it automatically.
• The display briefly shows “Update” during the process.
• After the update, the device reboots and resumes normal operation.

No manual intervention is required — the update happens fully automatically during a regular wake cycle. To trigger an immediate check, simply power-cycle the device.

Time Synchronisation

The device synchronises its clock via NTP (Network Time Protocol) using europe.pool.ntp.org:

• NTP sync occurs approximately every 60 minutes.
• Between syncs, the time is reconstructed from the last known time plus elapsed uptime.
• The display always shows local time with automatic daylight saving time switching (CET/CEST).

If the time shows --:-- on the display, NTP sync has not succeeded yet. This typically resolves on the next wake cycle (within 3 minutes).

Troubleshooting

References

• Hardware Guide — Board assembly, pinout, solar powering
• Software Guide — Development setup, build, MQTT topics
• Pool Controller
• Home Assistant
• Smart Swimming Pool Website