MeteoHubSensor

🇫🇷 Version française : README.fr.md

Standalone outdoor weather probe, linked over ESP-NOW to the MeteoHub station. Target board: ESP32-S3 Super Mini (RGB LED, no screen).

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1. Responsibility

MeteoHubSensor has a single responsibility: measure the outdoor environment and transmit its raw metrics over ESP-NOW.

This node is not a new morfSystem component. No web server, no local history.

Roles:

• Super Mini (Outdoor): "I measure, I blink the status, I transmit."
• MeteoHub: "I receive, validate, store, display and expose."

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2. ESP-NOW architecture

              ┌─────────────────┐
              │  ESP32-S3       │
              │  MeteoHub       │
              └────────┬────────┘
                       │ ESP-NOW
              ┌────────▼────────┐
              │  Super Mini     │
              │  RGB LED        │
              │  AHT20 / BMP280 │
              └────────┬────────┘
                       │
              ┌────────┴────────┐
              ▼                 ▼
         Temperature        Humidity

Changing hub: pairing with a long press on BOOT

The probe talks to a single MeteoHub, in unicast. That hub's MAC is stored in the probe's NVS: there is no need to know it at build time, nor to reflash to change hub.

1. Leave only the MeteoHub to pair powered on within radio range (MeteoHub ≥ 1.46.0).
2. With the probe running, hold BOOT for about 3 s, until the LED turns solid blue, then release: pairing starts on release. A press longer than 10 s is ignored (button considered stuck). Do not hold BOOT while plugging the probe in: that is the ESP32 flashing mode.
3. The probe sweeps channels 1 to 13 asking "who is a hub?". The hub answers with its identity and MAC; the probe confirms in unicast and waits for the hub's acknowledgement.
4. 3 green flashes: paired, the new MAC is in NVS and measurements go to this hub in unicast. 3 red flashes: failure, the previous association is kept as it was.

Rules:

• Deliberate only. A hub that is off or out of range never triggers a change of receiver: the probe keeps its measurements pending and keeps aiming at its hub.
• A failure erases nothing. Until a new hub has answered AND acknowledged the confirmation, the probe keeps the old MAC (in NVS and in memory).
• Several hubs in range. If two different hubs answer during the sweep, the probe refuses (red flashes) rather than pick one at random. Once paired, the other hubs can be switched back on: the probe finds ITS hub's channel through the exact BSSID of its "MH-NOW" access point, no longer through the first "MH-NOW" it sees.
• No duplicate, no gap. The confirmation carries the last measurement number acknowledged by the old hub: the new hub resumes from there and only receives the measurements still pending.
• Stuck button = no effect. A permanent press (an enclosure pressing the button, moisture on GPIO0) is never released: it starts no pairing, and the button wake-up is not even armed while GPIO0 stays low. Measurements carry on normally.
• Search bounded to 60 s. A short press is ignored.
• The hub (≥ 1.47.0) only archives the probe that chose it: a bench probe powered on next to it can no longer mix its readings with the outdoor ones. The press wakes the probe from sleep; it then goes back to sleep for the remaining time, without shifting the measurement cadence.

Without a stored pairing (new probe, erased flash), the probe sends nothing: ESPNOW_RECEIVER_MAC (include/config.h) is zero since 0.25.0. It keeps its measurements pending and no longer scans channels until a long press on BOOT has paired it. A hard-coded MAC would have targeted one specific hub, and after swapping hubs (production ↔ test bench) an erased probe would have sent its readings to the wrong hub.

Local buffer: no measurement lost, without draining the battery

Each measurement is written to flash before it is sent, then kept until the hub acknowledges it. If the hub is off or out of range, the probe later resends what is missing, in order, at most 10 measurements per wake-up. Retention: 30 days of pending measurements.

Since 0.24.0 this buffer is a segmented journal: one small file per day of measurements (/mhs/<seq>.seg), written by appending only. The acknowledgement watermark lives in NVS, and a fully acknowledged segment is deleted. The former buffer, a single 276 KB file, was copied in full by LittleFS at every measurement: 4.5 s measured, radio on. On the first boot in 0.24.0, the measurements still pending in the old file are taken over, then it is erased.

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3. Hardware

The pinout lives in include/board_config.h, selected by the SENSOR_BOARD_S3 define set by the PlatformIO environment.

ESP32-S3 Super Mini (env esp32-s3-supermini)

• 4 MB flash + 2 MB quad PSRAM (unused), native USB CDC. No screen (status on the LED).
• Status = RGB LED on GPIO 48 (blue acquisition, green OK, red error).
• I2C: SDA = GP8, SCL = GP9. Battery: 14500 Li-ion (Breadvolt), 100k/100k divider on GP4.
• ESP-NOW capped at 11 dBm (hardware constraint confirmed by testing: full power = no ACK).
• Sensors: AHT20 (T/H), BMP280 (pressure).
• Details (French): docs/cablage.md.

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4. RGB LED

• Blue: boot and acquisition.
• Green: delivery confirmed (the hub acknowledged, unicast ACK).
• Red: not delivered (no ACK from the hub).
• Solid blue (after ~3 s holding BOOT): pairing in progress.
• 3 green / red flashes: pairing succeeded / failed (association unchanged).

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5. Build and flash

1. Copy include/secrets_example.h to include/secrets.h in this project.

# ESP32-S3 Super Mini
pio run -e esp32-s3-supermini
pio run -e esp32-s3-supermini -t upload
pio run -e esp32-s3-supermini -t monitor

If the serial port does not show up: hold BOOT, tap RESET, release BOOT.

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6. Author & License

Developed by morfredus for the MeteoHub weather station. License: GPL v3.