README.md

💡 PWM Generation — Register-Level (Arduino UNO)

This project demonstrates Pulse Width Modulation (PWM) using Timer1 of the ATmega328P (Arduino UNO) — entirely through register-level programming, no Arduino functions involved.

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⚙️ Hardware Used

• Arduino UNO (ATmega328P)
• LED connected to pin D9 (OC1A)
• 220Ω current-limiting resistor

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🔌 Pin Configuration

Component	Function	Arduino Pin	Port
LED	PWM Output	D9	PB1 (OC1A)
VCC	Power	+5V	—
GND	Ground	GND	—

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🧩 Code Explanation

Registers Used

Register	Purpose
TCCR1A	Controls PWM mode and output behavior
TCCR1B	Sets waveform generation mode and prescaler
OCR1A	Output Compare Register (sets duty cycle)
DDRB	Configures PB1 as output

PWM Configuration

• Mode: Fast PWM (10-bit resolution)
• Output: Non-inverting mode
• Prescaler: 64
• PWM Frequency: ~250 kHz
• Output Pin: OC1A (PB1 → Arduino D9)

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⚙️ Working Principle

1. Timer1 generates a PWM signal at OC1A pin.
2. The duty cycle is adjusted from 0 → 100% → 0 in a smooth fade loop.
3. LED brightness increases and decreases continuously.

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🧰 Build & Upload

1. Compile using AVR-GCC / Atmel Studio / PlatformIO.
2. Flash the HEX file to Arduino UNO.
3. Observe the LED brightness fading up and down using hardware PWM.