Week 8  

I wanted to build a circuit similar to one I made in the past weeks but with a slight modification. I reused the fan but opted for a different type of LEDs Additionally, incorporating a Bluetooth module introduced a new feature to the project.

Tinker CAD

The Arduino that controls 3 LEDs (Red, Green, and Blue) and a Fan using serial communication. It waits for incoming data from the serial monitor (or another device) and responds by turning on/off the LEDs and the fan depending on the command it receives.

Variable Declarations:

int LEDR = 2; // Red LED on pin 2

int LEDG = 3; // Green LED on pin 3

int LEDB = 4; // Blue LED on pin 4

int Fan = 7;  // Fan on pin 7

char incomingData = '0'; // Variable to store incoming data (initialized to '0')

Assigning digital pins on the Arduino to control the Red, Green, and Blue LEDs, and a Fan.

incomingData holds the value received from serial input.

Setup Function:

void setup() {

  Serial.begin(9600);        // Starts serial communication at 9600 baud rate

  pinMode(LEDR, OUTPUT);     // Set LEDR pin as output

  pinMode(LEDG, OUTPUT);     // Set LEDG pin as output

  pinMode(LEDB, OUTPUT);     // Set LEDB pin as output

  pinMode(Fan, OUTPUT);      // Set Fan pin as output

}

This runs once when the Arduino powers on or resets.
Serial.begin(9600) initializes communication, allowing you to send commands via serial monitor.

pinMode(..., OUTPUT) configures the connected devices to receive signals from the Arduino.

Loop Function:
void loop() {

  while (Serial.available() == 0); // Wait until data is received

  incomingData = Serial.read();    // Read the incoming data from the serial buffer

The while (Serial.available() == 0); keeps looping until data is sent from the serial monitor (or external device). It blocks everything else until something arrives.

incomingData = Serial.read(); reads the first available character from the serial input.

Control Logic:

  if (incomingData == '1') {

    digitalWrite(LEDR, HIGH); // Turn Red LED ON

    digitalWrite(LEDG, LOW);  // Turn Green LED OFF

    digitalWrite(LEDB, LOW);  // Turn Blue LED OFF

    digitalWrite(Fan, LOW);   // Turn Fan OFF

  }

If i send '1' via serial, the Red LED turns ON, Green & Blue turn OFF, and the Fan is OFF.

cpp

CopyEdit

  else if (incomingData == '2') {

    digitalWrite(LEDR, LOW);

    digitalWrite(LEDG, HIGH); // Green LED ON

    digitalWrite(LEDB, LOW);

    digitalWrite(Fan, LOW);

  }

Sending '2' turns the Green LED ON, others OFF, and Fan OFF.

  else if (incomingData == '3') {

    digitalWrite(LEDR, LOW);

    digitalWrite(LEDG, LOW);

    digitalWrite(LEDB, HIGH); // Blue LED ON

    digitalWrite(Fan, LOW);

  }

Sending '3' turns the Blue LED ON, others OFF, and Fan OFF.

  else if (incomingData == '4') {

    digitalWrite(LEDR, HIGH);

    digitalWrite(LEDG, HIGH);

    digitalWrite(LEDB, HIGH); // All LEDs ON

    digitalWrite(Fan, LOW);

  }

Sending '4' turns all LEDs ON, and Fan OFF.

  else {

    digitalWrite(LEDR, LOW);

    digitalWrite(LEDG, LOW);

    digitalWrite(LEDB, LOW);  // All LEDs OFF

    digitalWrite(Fan, HIGH);  // Fan ON

  }

}

If i send anything else, it turns all LEDs OFF and turns the Fan ON.

The process was mainly trial and error. Also, my colleagues supported me in connecting the application through bluetooth/wifi. 

When I transfer the wiring from Tinkercad to the physical components, it rarely works smoothly on the first attempt. I usually go through several rounds of trial and error, making adjustments until everything functions correctly.

Also, when uploading the code to the Arduino, I’ve learned that it’s better to disconnect the Tx and Rx wires first to ensure a more stable connection. Once the upload is complete, I reconnect them to their original positions.