Circuit Documentation

Summary

The circuit is designed to interface various sensors and input devices with an ESP32 microcontroller for monitoring and control purposes. It includes environmental sensors (DHT22 for temperature and humidity, MQ-3 and MQ-5 for gas detection), a servo motor for actuation, RFID reader for identification, pushbuttons for user input, and an LCD display for output. The ESP32 serves as the central processing unit, running embedded code to interact with the connected devices, process sensor readings, and control the servo based on predefined conditions.

Component List

DHT22

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

MQ-3 Breakout

• Description: A gas sensor for detecting alcohol vapors.
• Pins: VCC, GND, DO, AO

ESP32 - 38 pins Expansion Board

• Description: A microcontroller with WiFi and Bluetooth capabilities.
• Pins: EN, SVP, SVN, P34, P35, P32, P33, P25, P26, P27, P14, P12, P13, SD2, SD3, CMD, 5V, P23, P22, TX, RX, P19, P18, P5, P17, P16, P4, P0, P2, P15, SD1, SD0, CLK, VCC, G, D22, D21, 3V, V, +, -

MQ-5

• Description: A gas sensor for detecting LPG, natural gas, and coal gas.
• Pins: VCC, GND, Digi Out, Analog out

Servo

• Description: A motor capable of precise position control.
• Pins: GND, VCC, PWM

Pushbutton

• Description: A momentary switch that can be used to trigger actions.
• Pins: Pin 2, Pin 1, Pin 3, Pin 4

Resistor

• Description: A passive two-terminal electrical component that implements electrical resistance.
• Properties: Resistance: 1000 Ohms

LCD I2C Display

• Description: A display module for showing text and numbers.
• Pins: GND, VCC, SDA, SCL

RFID-RC522

• Description: An RFID reader/writer module.
• Pins: VCC (3.3V), RST, GND, IRQ, MISO, MOSI, SCK, SDA

Wiring Details

DHT22

• + to ESP32 VCC
• Out to ESP32 P4
• - to ESP32 G

MQ-3 Breakout

• VCC to ESP32 5V
• GND to ESP32 G
• AO to ESP32 P14

MQ-5

• VCC to ESP32 5V
• GND to ESP32 G
• Analog out to ESP32 P15

Servo

• GND to ESP32 G
• VCC to ESP32 5V
• PWM to ESP32 P13

Pushbuttons

• Pin 2 to ESP32 5V
• Pin 1 to ESP32 P27, P26, P25 (one button per pin)
• Pin 4 to respective Resistor pin1

Resistor

• pin1 to Pushbutton Pin 4
• pin2 to ESP32 G

LCD I2C Display

• GND to ESP32 G
• VCC to ESP32 5V
• SDA to ESP32 P23
• SCL to ESP32 P22

RFID-RC522

• VCC (3.3V) to ESP32 3V
• RST to ESP32 P16
• GND to ESP32 G
• MISO to ESP32 P19
• MOSI to ESP32 P23
• SCK to ESP32 P18
• SDA to ESP32 P5

Documented Code

The embedded code for the ESP32 microcontroller is written in C++ and is used to control the circuit's functionality. The code includes libraries for interfacing with the LCD, RFID, DHT sensor, and servo motor. It defines pin assignments, initializes devices, and contains the main loop that handles RFID card reading, button debouncing, and mode selection. The code also includes functions for handling RFID card detection, checking authorized UIDs, running modes based on the detected chemical, adjusting the servo position, and handling button presses.

// Code is omitted for brevity. Please refer to the provided code input for the full source.

The code is structured into functions to improve readability and maintainability. It uses conditional statements to make decisions and control the flow of the program based on sensor readings and user inputs. The servo's position is adjusted according to the current mode and chemical detected, demonstrating a simple control system that could be expanded for more complex applications.