Control a custom hot tub using a bunch of relays and sensors.

This is work-in-progress.

• Control (via relays) of (at least):
  • 2-speed pumps
  • blower
  • heater
  • lights
  • (TBD) Valve actuators with smart power-off
• Reading temperature sensor data and tying it to controls (eg heater)
• Sheduling on/off behavior
• Overriding said schedule briefly (eg pump to high for 20 minutes)
• (TBD) Overriding said schedule in the future (eg heater up 10 degrees for the weekend)
• Web UI
• Touchscreen UI using wireless display/ESP32 boards via ESP-NOW protocol
• OTA updates

• Simple controls use single relays
• 2-speed controls use two SPDT relays (1 for on, 2 for speed), wired in series.

The project is two independent boards, each its own PlatformIO project:

• controller/ — the ESP32 that drives the relays and sensors and serves the web UI.
• display/ — an optional Sunton "CYD" touchscreen remote (ESP32-S3) that talks to the controller over ESP-NOW.

Shared message/type definitions live in hot_tub_types.h at the repo root and are pulled into both projects via the include path (-I.. in each platformio.ini), so there are no header copies or symlinks to maintain.

Both boards build with PlatformIO (pio). All dependencies are declared in each project's platformio.ini and fetched from the PlatformIO registry at build time — nothing large is vendored in git. The one exception is XPT2046_Touchscreen, kept under display/lib/ because it carries a small local patch (see below).

Each project has a Makefile too, but it is only a thin convenience wrapper around pio (make upload, make monitor, and — on the controller — a few HTTP helpers for OTA and live SPIFFS sync). There is no separate arduino-cli build path anymore.

1. Copy secrets.h.sample to secrets.h and edit for your settings.

cd controller
pio run -t upload      # build + flash the firmware
pio run -t uploadfs    # upload the web UI (data/) to SPIFFS — once, and after UI changes
pio device monitor     # serial console

The web UI is a single self-contained data/index.html (no CDN/jQuery), so it works offline on the controller's own AP. Firmware/filesystem/WiFi endpoints are behind HTTP Basic auth. See controller/README.md for details, credentials, and the make convenience targets.

cd display
pio run -t upload
pio device monitor

lvgl and Arduino_GFX come from the registry via platformio.ini; only XPT2046_Touchscreen is vendored (under display/lib/, auto-included by PlatformIO). The LVGL build config (display/lv_conf.h) is committed, so no setup step is needed — but if you change the pinned lvgl version, regenerate it from that version's lv_conf_template.h. Pin/panel/touch configuration lives in gfx.h and touch.h. See display/README.md.