feat: add mq2-gas-sensor

Author: AriellaE

docs/parts/wokwi-mq2-gas-sensor.md

@@ -0,0 +1,55 @@
+---
+title: wokwi-mq2-gas-sensor Reference
+sidebar_label: wokwi-mq2-gas-sensor
+---
+
+MQ2 Gas Sensor module
+
+<wokwi-gas-sensor />
+
+## Pin names
+
+| Name | Description           |
+| ---- | --------------------- |
+| VCC  | Positive power supply |
+| GND  | Ground                |
+| DO   | Digital output        |
+| AO   | Analog output         |
+
+## Attributes
+
+| Name      | Description                           | Default value |
+| --------- | ------------------------------------- | ------------- |
+| ppm       |       part per million       | "400"         |
+| threshold | Digital output threshold voltage      | "4.4"         |
+
+## Operation
+
+The MQ2 Gas Sensor is a semiconductor sensor that can detect the presence of various combustible gases including LPG, Propane, Hydrogen, Methane, and Carbon Monoxide. The sensor has both analog and digital outputs:
+
+- The analog output (AO) provides a continuous voltage reading that corresponds to the gas concentration(ppm). Higher gas concentration results in higher voltage output.
+- The digital output (DO) acts as a threshold detector - it goes LOW when gas concentration exceeds the threshold set by the potentiometer.
+
+To use the MQ2 sensor:
+
+1. Connect VCC to 5V power supply
+2. Connect GND to ground
+3. For analog readings:
+   - Connect AO to an analog input pin
+   - Read the analog value to get relative gas concentration
+4. For threshold detection:
+   - Connect DO to a digital input pin
+   - The pin will read LOW when gas concentration exceeds threshold
+   - Adjust threshold using the `threshold` attribute
+
+Note: In real hardware, the sensor needs a pre-heating time of about 20-30 seconds before taking readings. The simulator provides readings immediately.
+
+
+### Digital output
+
+The digital output (DO) pin will read LOW when gas concentration exceeds the threshold. The threshold is set by the `threshold` attribute. The default threshold is 4.4V.
+
+
+## Simulator examples
+
+- [MQ2 Gas Sensor Digital Example](https://wokwi.com/projects/424318978955716609)

docs/parts/wokwi-mq2-gas-sensor.svg

@@ -54,6 +54,7 @@ module.exports = {
       'parts/wokwi-membrane-keypad',
       'parts/wokwi-microsd-card',
       'parts/wokwi-mpu6050',
+      'parts/wokwi-mq2-gas-sensor',
       'parts/wokwi-nlsf595',
       'parts/wokwi-nokia-5110-screen',
       'parts/wokwi-ntc-temperature-sensor',