This project is an Arduino-based multi-sensor control system that integrates a Light Dependent Resistor (LDR), ultrasonic distance sensor, buzzer, DC motor (via L293D driver), and a 16x2 LCD display. The system measures ambient light, distance to an object, and controls a motor and buzzer accordingly, displaying real-time data on the LCD.

• LDR Sensor: Measures ambient light and calculates the resistance of the photoresistor.
• Ultrasonic Sensor: Measures the distance to an object in centimeters.
• Buzzer: Emits a tone whose frequency is mapped to the light intensity.
• DC Motor Control: Motor speed is adjusted based on the measured distance.
• LCD Display: Shows resistance (with Ω symbol), buzzer frequency, distance, and motor speed (RPM).

• Arduino Uno (or compatible)
• LDR (Light Dependent Resistor)
• 10kΩ resistor (for LDR voltage divider)
• Ultrasonic sensor (HC-SR04 or similar)
• Buzzer
• L293D Motor Driver IC
• DC Motor
• 16x2 LCD Display (compatible with LiquidCrystal library)
• Jumper wires, breadboard, and power supply

1. Initialization:
   The LCD displays "Initializing..." on startup.

2. Sensor Readings:

   • The LDR value is read and converted to resistance.
   • The ultrasonic sensor measures distance to the nearest object.

3. Output Control:

   • The buzzer emits a tone mapped to the light intensity.
   • The DC motor speed is mapped to the measured distance (closer object = slower speed).

4. Display:
   The LCD shows:

   • Top row: LDR resistance (Ω), buzzer frequency (Hz)
   • Bottom row: Distance (cm), motor speed (RPM)

1000Ω=>1500HZ 20cm=>120RPM 

The main logic is implemented in [Arduino.ino]

• Reads LDR and calculates resistance.
• Reads distance from ultrasonic sensor.
• Maps sensor values to buzzer frequency and motor speed.
• Updates the LCD with real-time values.

1. Wiring:
   Connect all components according to the pin mapping above.

2. Upload Code:
   Open [Arduino.ino] in the Arduino IDE and upload it to your Arduino board.

3. Power Up:
   Power the Arduino and observe the LCD and hardware responses.

You can view and simulate the circuit on TinkerCAD using the following link:
Open TinkerCAD Simulation

This repository also includes two 8051 assembly language programs that demonstrate microcontroller programming with the Atmel 8051 MCU:

An assembly implementation of a calculator that:

• Performs arithmetic operations (multiplication and division)
• Displays results on a 16x2 LCD display
• Features:
  • Performs hex arithmetic operations on 8-bit values
  • Displays input values and results on an LCD
  • First line shows input values: "T:xxH U:xxH"
  • Second line shows calculation results: "T:xxxxxx Q:xxxx"
  • Includes comprehensive LCD control routines
  • Handles hexadecimal to ASCII conversion for display

A countdown timer with alarm functionality:

• Uses Timer1 interrupts for accurate timing
• Displays countdown on a 4-digit 7-segment display
• Starts countdown from the value 9558
• Activates a buzzer/alarm (on P1.5) when the countdown reaches 0508
• Features:
  • Display multiplexing for the 7-segment displays
  • BCD countdown logic with carry handling
  • Customized delay routines for display stability
  • Interrupt-driven timing for accuracy

Both assembly programs demonstrate low-level hardware control, interrupt handling, and I/O operations on the Atmel 8051 microcontroller architecture.

For the 8051 assembly programs, you'll need:

• Atmel 8051 microcontroller (AT89C51/52 or compatible)
• For Calculator: 16x2 LCD display connected to Port 0 and Port 2
• For Timer: 4-digit 7-segment display (common cathode) connected to Port 0 and Port 2
• Buzzer connected to P1.5 (for the Timer program)
• 11.0592 MHz crystal oscillator
• 5V power supply
• Associated passive components (resistors, capacitors)

• Arduino.ino: Main Arduino source code.
• Calculator.asm: Assembly code for a calculator (unrelated to Arduino sketch).
• Timer.asm: Assembly code for a timer (unrelated to Arduino sketch).