A tiny hardware project for Festiwal Światła - a choker with a LED strip displaying air quality (aka a choker showing when you are going to choke)

• ESP32. XIAO ESP32S3 was used, but any similar chip should work. Consider using a chip with integrated Stemma QT connector (like Adafruit QT Py RP2040) to avoid unnecessary soldering. Processes air quality and displays it on the LED strip (also sends over MQTT if needed)
• Adafruit SGP40 Air Quality Sensor Breakout. Monitors air quality and gives it out in [0-500] range
• Any suitable LED strip (1 LED/cm is preferrable)
• An actual choker to attach the stip. This can potentially hold just on the led strip, but having a choker gives control over the length and a decent base
• Powered via powerbank, but possible to solder a battery (if 3V pin is used for LEDs)

• Connect SGP40 to ESP32 via Stemma QT cable (SDA, SCL, GND, 3V)
• Connect LEDs to ESP32 (data pin, GND, 5V)

Built with PlatformIO and VSCode. Most logic are in leds_controller.cpp. Sensor fetching and LEDs update are done on separate cores, as sensor takes ~100-200ms to get the data, which is not suitable for smooth LED animation. It is also able to send measurtement data over MQTT ()

• If you don't need MQTT - use no_mqtt env
• Set DATA_PIN in leds_controller.cpp (TODO: pass from env?)
• For MQTT use production env
  • Copy secrets.ini.example into secrets.ini and set appropriate values for WiFi and MQTT connections

Animation is basically:

• Air quality converted to color via color palette
• Color is set to the whole LED strip, with brightness adjusted as a moving sine-wave (with some gamma corrections)