Week 8 - Journal

At first, I came up with the idea of a simple yet expressive way to communicate my mood without needing to say a word. I planned to use an RGB LED to visually indicate different moods and an LCD 1602 I2C display to show corresponding text messages. The idea was to control everything wirelessly using an Android app via a Bluetooth module.

I started by defining the four different moods and their corresponding LED colors and messages:

• Pressing '1' on the app: The Red LED lights up, and the LCD displays "Asmaa's Stressed" to signal that I need space.

• Pressing '2': The Green LED lights up, and the LCD shows "Relaxed!" to indicate that I’m in a good mood.

• Pressing '3': The Blue LED lights up, and the LCD displays "Deep Focus", letting others know that I’m concentrating.

• Pressing '4': The Purple LED lights up, and the LCD humorously states "COFFEE is needed", signaling that I’m running low on caffeine and energy.

Once I finalized the mood-to-message mapping, I moved on to the wiring.

How It Works:

1. The Bluetooth module connects to an Android phone via a Bluetooth control app.

2. The app sends commands ('1', '2', '3', or '4') over serial communication to the Arduino.

3. The Arduino reads the received data using Serial.read().

4. Based on the received number:

   • The RGB LED changes color accordingly.

   • The LCD displays the corresponding message.

5. The setColor() function sets the appropriate PWM values for the RGB LED to achieve the desired color.

I first tested everything on a breadboard, ensuring each component worked correctly. After verifying the Bluetooth communication and LCD response, I finalized the setup and secured the circuit components inside a cardboard enclosure . I used a glue gun to hold the circuit in place and made cutouts to display the LCD and allow easy visibility of the RGB LED.

Arduino code 

Libraries and Initialization

#include <Wire.h>

#include <LiquidCrystal_I2C.h>

• Wire.h: Enables communication with I2C devices (like the LCD).

• LiquidCrystal_I2C.h: Library for controlling an LCD with an I2C interface.

LCD and LED Setup

LiquidCrystal_I2C lcd(0x27, 16, 2);

• Creates an LCD object with the I2C address 0x27, 16 columns, and 2 rows.

• This means the LCD can display two lines of text, each 16 characters long.

const int redPin = 9;

const int bluePin = 11;

• Defines the RGB LED pin connections.

• Here, only Red and Blue pins are used (Green is missing).

Setup Function (Runs Once at Start)

void setup() {

  Serial.begin(9600);

• Initializes serial communication at 9600 baud rate for Bluetooth connection.

 lcd.init();

  lcd.backlight();

  lcd.clear();

  lcd.setCursor(0, 0);

  lcd.print("Bluetooth Control");

• Initializes the LCD, turns on the backlight, and displays "Bluetooth Control".

 pinMode(redPin, OUTPUT);

  pinMode(bluePin, OUTPUT);

• Sets RGB LED pins as OUTPUT.

 digitalWrite(redPin, LOW);

  digitalWrite(bluePin, LOW);

• Turns off all LEDs at startup.

Loop Function (Runs Continuously)

if (Serial.available() > 0) {

    char command = Serial.read(); // Read the incoming command

• Checks if a Bluetooth command has been received.

• Reads the command as a single character ('1', '2', '3', etc.).

Command Processing

switch (command) {

• Uses a switch-case to handle different Bluetooth commands.

Case 1: Red LED (Stress Mode)

case '1':

  setColor(255, 0, 0); // Red

  lcd.clear();

  lcd.setCursor(0, 0);

  lcd.print("Asmaa's Stressed");

  break;

• Turns on the Red LED (full brightness, 255).

• Clears the LCD and displays "Asmaa's Stressed".

Case 2: Blue LED (Focus Mode)

case '2':

  setColor(0, 0, 255); // Blue

  lcd.clear();

  lcd.setCursor(0, 0);

  lcd.print("Deep focus");

  break;

• Turns on the Blue LED (full brightness).

• Displays "Deep focus" on the LCD.

Case 3: Purple LED (Coffee Mode)

case '3':

  setColor(128, 0, 128); // Purple

  lcd.clear();

  lcd.setCursor(0, 0);

  lcd.print("COFFEE is needed");

  break;

• Combines Red (128) and Blue (128) to create Purple.

• Displays "COFFEE is needed" on the LCD.

Default Case: No Command Received

default:

  setColor(0, 0, 0); // Off

  lcd.clear();

  lcd.setCursor(0, 0);

  lcd.print("No command");

  break;

• Turns off the LED (sets brightness to 0).

• Displays "No command" on the LCD.

RGB LED Control Function

void setColor(int red, int green, int blue) {

  analogWrite(redPin, red);

  analogWrite(bluePin, blue);

}

• Controls the brightness of the LED colors using PWM (analogWrite).

• Problem: Green LED pin is missing! (should be added to support full RGB colors).

Wiring Details:

Bluetooth Module (HC-05/HC-06):

• TX → Arduino RX (pin 0) (Used a voltage divider: 1kΩ + 2kΩ to step down 5V to 3.3V)

• RX → Arduino TX (pin 1)

• VCC → 5V

• GND → GND

RGB LED (Common Cathode):

• Red pin → Arduino pin 9 

• Green pin → Arduino pin 12 

• Blue pin → Arduino pin 11 

• Cathode (common) → GND

LCD 1602 I2C Display:

• SDA → Arduino A4

• SCL → Arduino A5

• VCC → 5V

• GND → GND