Circuit Documentation

Summary

This document provides a detailed overview of a circuit that includes an ESP32 microcontroller, a toggle switch, a 16x2 I2C LCD, a 5V 2-relay module, a SIM900A GSM module, a 5V battery, a 12V power supply, and a resistor. The circuit is designed to interface these components to create an IoT meter project.

Component List

1. Toggle Switch

   • Description: A simple toggle switch used to control the circuit.
   • Pins: Vcc, Sig, Gnd

2. ESP32 (30 pin)

   • Description: A powerful microcontroller with built-in Wi-Fi and Bluetooth capabilities.
   • Pins: EN, VP, VN, D34, D35, D32, D33, D25, D26, D27, D14, D12, D13, GND, Vin, D23, D22, TX0, RX0, D21, D19, D18, D5, TX2, RX2, D4, D2, D15, 3V3

3. Resistor

   • Description: A resistor used to limit current in the circuit.
   • Pins: pin1, pin2
   • Properties: Resistance: NaN Ohms

4. 5V 2-Relay JD-VCC

   • Description: A relay module used to control high voltage devices.
   • Pins: JD-VCC, VCC, GND, IN1, IN2, NO, COM, NC

5. 5V Battery

   • Description: A 5V battery used to power the circuit.
   • Pins: positive, negative

6. 16x2 I2C LCD

   • Description: A 16x2 character LCD with I2C interface.
   • Pins: GND, VCC, SDA, SCL

7. 12V Power Supply

   • Description: A 12V power supply used to power the SIM900A module.
   • Pins: +, -

8. SIM900A

   • Description: A GSM module used for communication.
   • Pins: GND, DB9-3 (RXD), DB9-2 (TXD), 5V, 3VR, 5VR, 3VT, 5VT, VCC, Ring, RESTART, RESET, STATUS

Wiring Details

Toggle Switch

• Vcc is connected to:

  • Resistor pin2
  • ESP32 D26

• Sig is connected to:

  • 16x2 I2C LCD GND
  • ESP32 GND

ESP32 (30 pin)

• D26 is connected to:

  • Toggle Switch Vcc
  • Resistor pin2

• GND is connected to:

  • Toggle Switch Sig
  • 16x2 I2C LCD GND
  • 5V 2-Relay JD-VCC GND
  • 5V Battery negative

• Vin is connected to:

  • 16x2 I2C LCD VCC

• D22 is connected to:

  • 16x2 I2C LCD SCL

• D21 is connected to:

  • 16x2 I2C LCD SDA

• D5 is connected to:

  • 5V 2-Relay JD-VCC IN1

• TX2 is connected to:

  • SIM900A DB9-2 (TXD)

• RX2 is connected to:

  • SIM900A DB9-3 (RXD)

• D2 is connected to:

  • 5V 2-Relay JD-VCC IN2

• 3V3 is connected to:

  • Resistor pin1

Resistor

• pin2 is connected to:

  • Toggle Switch Vcc
  • ESP32 D26

• pin1 is connected to:

  • ESP32 3V3

5V 2-Relay JD-VCC

• IN1 is connected to:

  • ESP32 D5

• IN2 is connected to:

  • ESP32 D2

• GND is connected to:

  • 5V Battery negative
  • ESP32 GND

• VCC is connected to:

  • 5V Battery positive

5V Battery

• positive is connected to:

  • 5V 2-Relay JD-VCC VCC

• negative is connected to:

  • 5V 2-Relay JD-VCC GND
  • ESP32 GND

16x2 I2C LCD

• GND is connected to:

  • Toggle Switch Sig
  • ESP32 GND

• VCC is connected to:

  • ESP32 Vin

• SCL is connected to:

  • ESP32 D22

• SDA is connected to:

  • ESP32 D21

12V Power Supply

• + is connected to:

  • SIM900A 5V

• - is connected to:

  • SIM900A GND

SIM900A

• DB9-2 (TXD) is connected to:

  • ESP32 TX2

• DB9-3 (RXD) is connected to:

  • ESP32 RX2

• 5V is connected to:

  • 12V Power Supply +

• GND is connected to:

  • 12V Power Supply -

Code Documentation

ESP32 Code

#include <LCD-I2C.h>

LCD_I2C lcd(0x27, 16, 2); // Default address of most PCF8574 modules, change according

void setup() {
    // If you are using more I2C devices using the Wire library use lcd.begin(false)
    // this stop the library(LCD-I2C) from calling Wire.begin()
    lcd.begin();
    lcd.display();
    lcd.backlight();
}

void loop()
{
    lcd.print("IOT METER PROJECT"); // You can make spaces using well... spaces
    lcd.setCursor(5, 1); // Or setting the cursor in the desired position.
    lcd.print(" TEST!");
    delay(500);

    // Flashing the backlight
    for (int i = 0; i < 5; ++i)
    {
        lcd.backlight();
        delay(50);
        lcd.backlightOff();
        delay(50);
    }

    lcd.backlight();
    lcd.clear();
    delay(500);
}

5V 2-Relay JD-VCC Code

void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:

}

16x2 I2C LCD Code

void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:

}

This documentation provides a comprehensive overview of the circuit, including component descriptions, wiring details, and the code used in the microcontrollers.