ESP32-C6 Plant Monitor

ESP-IDF firmware for Seeed Studio XIAO ESP32-C6 plus a Home Assistant MQTT companion integration: six soil ADC channels publishing raw readings over MQTT, discovery metadata, host-driven per-channel masking, and per-channel raw dry thresholds with binary_sensor alarms (all stored in Home Assistant, not direct database writes).

Path	Purpose
firmware/	ESP-IDF 5.x / 6.x, target esp32c6; Wi-Fi, NTP, HTTP JSON config, MQTT + Home Assistant discovery.
custom_components/plant_monitor/	Six raw-ADC number thresholds + six binary_sensor dry alarms linked to MQTT telemetry.
docs/hardware_xiao_esp32c6.md	MCU ↔ pin mapping for the six analog inputs.
docs/homeassistant.md	MQTT topic contract, www/ JSON example, integration steps.

Firmware quick start

1. Install ESP-IDF (5.x or 6.x) with esp32c6 support.

2. cd firmware

3. If set-target ever failed or build is not a clean CMake tree: delete the folder manually, then continue (PowerShell: Remove-Item -Recurse -Force .\build from firmware/).

4. Set the MCU first — this writes sdkconfig for esp32c6. If you skip this, CMake may default to esp32 and the toolchain will be wrong:

   idf.py set-target esp32c6

5. ESP-IDF 6+ managed components: MQTT and cJSON are no longer bundled as components/mqtt and components/json. This repo lists espressif/mqtt and espressif/cjson in firmware/main/idf_component.yml; the first configure/build downloads them (network required).
   If CMake reports unknown component 'mqtt' or unknown component 'json' (or missing cJSON), add the managed deps once from firmware/:

   idf.py add-dependency "espressif/mqtt"
   idf.py add-dependency "espressif/cjson"

6. idf.py menuconfig — optional but recommended to set Wi‑Fi, broker URL, device registry URL, and Power / sleep behaviour (see below).
   menuconfig runs CMake like build; it does not replace set-target.

   • Plant Monitor (ESP32-C6) → Power / sleep behaviour:
     • Deep sleep between measurements (default): uses Deep sleep duration (seconds), then sleeps — best on battery.
     • Continuous (debug, no deep sleep): loop + delay between measurements — best for USB serial debugging (no prompt during flash; you choose here).

7. idf.py build — optional explicit compile (or go straight to idf.py flash monitor, which builds if needed):

   idf.py build
   idf.py -p PORT flash monitor

The serial log prints the compact Wi-Fi MAC used when adding the Home Assistant integration.

MQTT connect drops (firmware vs. infrastructure)

Firmware retries MQTT and (in continuous debug mode) keeps a single session open to reduce connect/TLS churn. If the broker still closes the TCP connection during handshake (serial log e.g. mqtt_message_receive() returned 0), treat that as an infrastructure issue as well:

1. Inspect Mosquitto / Home Assistant MQTT broker logs at the same time as the device (disconnect reason, auth, limits).
2. Check client limits, listener caps, and ACLs if the broker rejects half-open or rapid sessions.
3. For mqtts://, verify TLS/time on the device (SNTP) and broker certificate expectations.
4. Review Wi‑Fi signal and stability (weak links often show up as sporadic TLS or TCP failures).

Firmware build troubleshooting

• fullclean / set-target refuses (“doesn't seem to be a CMake build directory”): delete firmware/build manually, then run idf.py set-target esp32c6 again.
• Wrong chip in the log (esp32 vs esp32c6, wrong compiler triplet like xtensa-esp32-elf instead of riscv32 for C6): your sdkconfig still targets the wrong SoC — delete firmware/build and (if unsure) firmware/sdkconfig, then run idf.py set-target esp32c6 and build again.

Home Assistant

Install with HACS (custom repository)

1. In Home Assistant, open HACS → Integrations (the left tab for integrations, not "Frontend").
2. Open the menu (three dots, top right) → Custom repositories.
3. Repository: paste your Git URL, e.g. https://github.com/boexler/ESP32-PlantMonitor (use SSH if you prefer: git@github.com:boexler/ESP32-PlantMonitor.git).
4. Category: select Integration.
5. Click Add. HACS reads the root hacs.json and lists the integration.
6. Open the new Plant Monitor (ESP32 MQTT) card → Download (pick a version or the default branch).
7. Restart Home Assistant (Settings → System → Restart).
8. Settings → Devices & services → Add integration → Plant monitor, then enter MQTT topic prefix and device MAC (see docs/homeassistant.md).

Requires the built-in MQTT integration to be connected to your broker before adding this integration.

Manual install (without HACS)

Copy custom_components/plant_monitor into your HA config folder, restart, then add the Plant monitor integration as above. Details: docs/homeassistant.md.