Circuit Documentation

Summary of the Circuit

This circuit is designed to control a 4-channel relay module via Bluetooth communication using an Arduino Nano as the microcontroller. The HC-05 Bluetooth module is used to receive commands wirelessly from a Bluetooth-enabled device. The Arduino Nano processes these commands and controls the relay module accordingly, which can switch four separate circuits, potentially connected to AC or DC loads. An AC to DC converter is included to provide the necessary 5V power supply to the Arduino Nano, the relay module, and the Bluetooth module from an AC source.

Component List

Arduino Nano

• Microcontroller board based on the ATmega328P
• It has a variety of digital and analog I/O pins
• Capable of serial communication via UART

HC-05 Bluetooth Module

• Bluetooth module for wireless communication
• Operates with a supply voltage of 3.3V to 6V
• Has TXD and RXD pins for serial communication with the Arduino Nano

Relay 4 Channel 5V

• A 4-channel relay module that can control up to four separate circuits
• Each channel has a Normally Open (NO) and a Normally Closed (NC) contact
• Operates with a 5V supply and has digital input pins to control each relay

AC to DC Converter (labeled as "actodc")

• Converts AC voltage to a 5V DC output
• Provides power to the Arduino Nano, relay module, and Bluetooth module

AC Source

• Provides the AC voltage input to the AC to DC converter

Wiring Details

Arduino Nano

• D1/TX connected to HC-05 Bluetooth Module RXD
• D0/RX connected to HC-05 Bluetooth Module TXD
• D2 to D5 connected to Relay 4 Channel 5V IN1 to IN4 respectively
• GND connected to the common ground net
• 5V connected to the 5V power net

HC-05 Bluetooth Module

• RXD connected to Arduino Nano D1/TX
• TXD connected to Arduino Nano D0/RX
• GND connected to the common ground net
• VCC connected to the 5V power net

Relay 4 Channel 5V

• IN1 to IN4 connected to Arduino Nano D2 to D5 respectively
• GND connected to the common ground net
• VCC connected to the 5V power net

AC to DC Converter (actodc)

• 12v, -, 5v, live, neutral pins are present
• 5v connected to the 5V power net
• - connected to the common ground net
• live connected to AC Source +
• neutral connected to AC Source -

AC Source

• + connected to AC to DC Converter live
• - connected to AC to DC Converter neutral

Documented Code

#include <SoftwareSerial.h> 
SoftwareSerial module_bluetooth(0, 1); // pin RX | TX

char data = 0;             
void setup() 
{
  Serial.begin(9600);         
  pinMode(2, OUTPUT);  // Initialize PIN 2 as Output
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
  digitalWrite(2, HIGH); // Set HIGH initially to turn off relay (active-low)
  digitalWrite(3, HIGH);
  digitalWrite(4, HIGH);
  digitalWrite(5, HIGH);
  
}
void loop()
{
  if(Serial.available() > 0)  
  {
    data = Serial.read(); // Read incoming data      
    if(data == '1'){
      digitalWrite(2, LOW); // Turn on relay
    }
    else if(data == '2'){      
      digitalWrite(2, HIGH); // Turn off relay
    } 
    else if(data == '3'){
      digitalWrite(3, LOW); 
    }
    else if(data == '4'){      
      digitalWrite(3, HIGH); 
    } 
    else if(data == '5'){
      digitalWrite(4, LOW); 
    }
    else if(data == '6'){      
      digitalWrite(4, HIGH); 
    } 
    else if(data == '7'){
      digitalWrite(5, LOW); 
    }
    else if(data == '8'){      
      digitalWrite(5, HIGH); 
    } 
   
                             
}

This code is designed to run on the Arduino Nano and listens for serial input. When a character is received, it checks the character and toggles the corresponding relay channel. The relays are controlled by digital pins 2 to 5. The relays are active-low, meaning that setting the pin to LOW turns the relay on, and setting it to HIGH turns it off.