Connecting an audible or visual alarm to your Gadget CO₂ monitor is straightforward: a piezoelectric buzzer, a NeoPixel LED strip or a relay to activate an extractor fan. The unified output system allows you to trigger any of these based on CO₂ thresholds with configurable hysteresis.
Contents
Available departures
| Departure | GPIO pins | Function |
|---|---|---|
| Orange Relay | GPIO 32 (depending on the board) | It is triggered when the orange level is reached |
| Red Relay | GPIO 33 (depending on the board) | It is triggered when the red level is reached |
| NeoPixel | GPIO 26 (depending on the board) | Configurable WS2812B LED strip |
| Buzzer | GPIO 2 (depending on the board) | Passive buzzer with configurable tone and duration |
Relay mode vs LED mode
The orange and red outputs can operate in two modes: Relay (the orange outlet remains active even if the red one is activated, ideal for ventilation) or LED (the orange output switches off when the red one is activated). Configurable from Settings → Output Configuration → GPIO Outputs.
NeoPixel (WS2812B)
Supports WS2812B addressable LED strips with the following type selection: NEOGRB, NEORGB, NEO_RGBW. Brightness adjustable from 0 to 255. Requires 5V (use a step-up converter if running on battery power).
Buzzer
Configurable passive buzzer: pitch (300–2000 Hz), beep duration (50–300 ms) and mode (OFF, once, every X seconds). It is automatically disabled within the menu to avoid causing a nuisance.
Hysteresis
All departures have configurable hysteresis to prevent them from switching on and off continuously if the concentration fluctuates around the threshold.
Notes
- The GPIO pins vary depending on the board (see the pinout table)
- For standard RGB LEDs, use the relay outputs with a resistor in series (330–470 Ω)
- CO2 Gadget offers a more versatile output system than any commercial meter
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