Circuit Documentation

Summary

The circuit in question is designed to interface various sensors and indicators with an ESP8266 NodeMCU microcontroller. The sensors include a DHT22 temperature and humidity sensor, an MQ-4 methane gas sensor, and a KY-026 flame sensor. Additionally, there are two LEDs (one green and one red) that serve as indicators. The circuit is powered by the 3.3V supply from the ESP8266 NodeMCU, and all ground connections are common to the microcontroller's ground. The DHT22 sensor's data output is connected to a digital pin on the microcontroller, while the MQ-4 and KY-026 sensors are interfaced through both analog and digital pins. Each LED is controlled by a separate digital pin on the microcontroller.

Component List

DHT22 Temperature and Humidity Sensor

• Pins: +, Out, -
• Description: A sensor for measuring ambient temperature and humidity.

ESP8266 NodeMCU Microcontroller

• Pins: D0, D1, D2, D3, D4, 3V3, GND, D5, D6, D7, D8, RX, TX, A0, RSV, SD3, SD2, SD1, CMD, SD0, CLK, EN, RST, VIN
• Description: A Wi-Fi capable microcontroller with digital and analog I/O pins.

MQ-4 Methane Gas Sensor

• Pins: A0, D0, GND, VCC
• Description: A sensor for detecting methane gas concentrations in the air.

LED: Two Pin (Green)

• Pins: cathode, anode
• Description: A green light-emitting diode used as an indicator.

KY-026 Flame Sensor

• Pins: A0, GND, VCC, D0
• Description: A sensor for detecting the presence of a flame or fire.

LED: Two Pin (Red)

• Pins: cathode, anode
• Description: A red light-emitting diode used as an indicator.

Wiring Details

DHT22 Temperature and Humidity Sensor

• + to 3.3V power supply
• Out to ESP8266 NodeMCU D4
• - to Ground

ESP8266 NodeMCU Microcontroller

• 3V3 to 3.3V power supply for all components requiring VCC
• GND to Ground for all components requiring Ground
• D4 to DHT22 Out
• A0 to MQ-4 A0
• D3 to Green LED anode
• D1 to KY-026 Flame Sensor D0
• D2 to Red LED anode

MQ-4 Methane Gas Sensor

• A0 to ESP8266 NodeMCU A0
• D0 not connected
• GND to Ground
• VCC to 3.3V power supply

LED: Two Pin (Green)

• cathode to Ground
• anode to ESP8266 NodeMCU D3

KY-026 Flame Sensor

• A0 not connected
• GND to Ground
• VCC to 3.3V power supply
• D0 to ESP8266 NodeMCU D1

LED: Two Pin (Red)

• cathode to Ground
• anode to ESP8266 NodeMCU D2

Documented Code

No code was provided for the microcontroller. To fully utilize the circuit, embedded code should be written to initialize and read data from the sensors, control the LEDs based on sensor inputs, and handle any communication or data processing required by the application. The code should be structured to include setup and loop functions, sensor reading functions, and output control for the LEDs.