Smart Lighting System

Overview

This project implements a Smart Lighting System using a PIC18F4620 microcontroller, an LDR (Light-Dependent Resistor) sensor, and a PIR (Passive Infrared) sensor. The system intelligently controls an LED to simulate lighting automation based on ambient light conditions and motion detection. It is programmed in PIC Assembly Language.

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Features

1. Light Control with LDR:
   • Monitors ambient light levels using an LDR.
   • Automatically turns the LED on in low-light conditions (night) and off in bright conditions (day).
2. Motion Detection with PIR:
   • Detects motion using a PIR sensor.
   • Temporarily turns on the LED for 15 seconds if motion is detected, regardless of ambient light.
3. Timer-Based Delay:
   • Configures Timer0 to generate accurate delays for timed LED control.
4. Debugging Support:
   • Configures the EUSART module for potential debugging via serial communication.
5. Interrupt Handling:
   • High-priority interrupts handle Timer0 and PIR motion detection events.

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Hardware Requirements

• Microcontroller: PIC18F4620
• Sensors:
  • LDR sensor (connected to the ADC pin AN0)
  • PIR sensor (connected to external interrupt pin INT1)
• Output Device:
  • LED (connected to RC0)
• Power Supply: 5V regulated power source
• Additional Components:
  • Resistors for LDR voltage divider.
  • Capacitors for noise filtering.
  • Breadboard and connecting wires.

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Software Requirements

• Assembler: MPLAB X IDE with PIC-AS assembler.
• Simulation: Proteus for circuit simulation (optional).

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System Architecture

1. LDR Threshold Logic:
   • The ADC reads the voltage from the LDR.
   • If the ADC value is below the configured threshold, the system considers it "night" and turns on the LED.
2. PIR Motion Detection:
   • If motion is detected, the PIR triggers an external interrupt.
   • The interrupt service routine (ISR) turns on the LED for 15 seconds, regardless of ambient light conditions.
3. Timer0 Configuration:
   • Timer0 generates precise delays for system timing.
4. Interrupt Priority:
   • PIR interrupts have higher priority than Timer0 to ensure immediate response to motion.

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Pin Configuration

Pin	Function	Description
RA0	LDR Sensor (AN0)	Reads ambient light levels via ADC.
RB0	PIR Sensor (INT1)	Detects motion using external interrupt.
RC0	LED	Controls the LED based on conditions.
OSC	Internal Oscillator	Configured to 8 MHz.

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Project Workflow

1. Initialization:
   • Configures the internal oscillator to 8 MHz.
   • Initializes ADC, Timer0, LED, and interrupt settings.
2. Main Loop:
   • Continuously monitors ambient light levels using ADC.
   • Updates the LED state based on the LDR sensor and PIR input.
3. Interrupts:
   • PIR (INT1):
     • Activates LED for 15 seconds when motion is detected.
   • Timer0:
     • Generates the delay required for the PIR timer.

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Configuration Bits

• Internal Oscillator: INTIO67
• Fail-Safe Clock Monitor: Disabled
• Watchdog Timer: Disabled
• Low-Voltage Programming: Disabled
• Brown-out Reset: Disabled

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Assembly Code Structure

1. Main Code:
   • System initialization and main loop.
2. Subroutines:
   • ADC configuration and reading.
   • Timer0 configuration and delay generation.
   • LED control logic.
3. Interrupt Service Routines:
   • Handles PIR motion detection and Timer0 delays.

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Code Highlights

ADC Initialization

; Configure ADC to read from AN0
BCF ADCON0, 2 ; Set the ADC channel to AN0
BSF ADCON0, 0 ; Enable ADC
BCF ADCON1, 0 ; Configure AN0 as analog input

LED Control

; Turn LED on/off based on LDR threshold
BTFSS threshold_flag, 0
BCF LATC, 0 ; Turn off LED (day)
BTFSC threshold_flag, 0
BSF LATC, 0 ; Turn on LED (night)

PIR Interrupt

; ISR for PIR motion detection
INT1_ISR:
    BCF INTCON3, 0 ; Clear INT1 interrupt flag
    BSF LATC, 0     ; Turn on LED
    MOVLW 0x0Fh     ; Start 15s delay
    MOVWF delay_15s
    CALL start_timer0

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Simulation and Testing

1. Proteus Simulation:
   • Simulate the circuit to verify LED behavior with varying light and motion conditions.
2. Debugging:
   • Use EUSART to monitor ADC readings and threshold values.

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Future Enhancements

• Add more sensors for environmental monitoring.
• Integrate PWM to adjust LED brightness dynamically.
• Implement a real-time clock (RTC) for scheduled operations.

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Project Schematic

Authors

• Mohamed Olwi
• Sama Mohamed