- Mechatronics LAB- Internet Of Things

Control LED Brightness Using Arduino and Python with PyFirmata - Beginner Guide

Objective

This guide will demonstrate how to control LED brightness using Arduino and Python with the PyFirmata library. You will learn to gradually increase and decrease the brightness of an LED connected to an Arduino board.

Project Goals

Connect to an Arduino board via Python using PyFirmata.
Control an LED's brightness using Pulse Width Modulation (PWM).
Implement a smooth transition effect for the LED brightness.

Required Components

Component	Description	Link
Arduino Uno	Main microcontroller for controlling the LED	Amazon Link
LED	Light Emitting Diode for brightness control	Amazon Link
220Ω Resistor	Limits current through the LED	Amazon Link
Jumper Wires	Connects components to Arduino	Amazon Link

Understanding the Circuit Basics

This project utilizes an LED connected to a digital pin on the Arduino. The brightness is controlled using PWM signals, which allow for smooth brightness transitions.

Connection	Description
Arduino Pin 5	Connected to the anode of the LED through a resistor
GND	Connected to the cathode of the LED

Circuit Connection Analysis

By connecting the LED to digital pin 5 on the Arduino and using a resistor to limit current, we can control the LED's brightness using PWM. The code will gradually increase and decrease the brightness, creating a fade effect.

Safety Tips

Always use a current-limiting resistor with LEDs to prevent damage.
Ensure all connections are secure before powering on the Arduino.

Python Programming Section

Key Python Functions Used

Arduino('COM8') – Connects Python to the Arduino on the specified COM port.
led_pin.write(value) – Sets the PWM value for the LED (0.0 to 1.0 scale).
time.sleep(seconds) – Pauses the program for a specified duration.

Setting Up the Python Environment

Install the PyFirmata library in Python by running: pip install pyfirmata.
Connect your Arduino to the computer and note the COM port it is connected to (e.g., COM8).

Python Code for Controlling LED Brightness


from pyfirmata import Arduino, util
import time

# Establish connection to the Arduino board (replace 'COM8' with your specific port)
board = Arduino('COM8')

# Set up the LED on digital pin 5 as a PWM output
led_pin = board.get_pin('d:5:p')  # Digital pin 5 as PWM output

# Start an iterator to continuously update the pin values from the Arduino
it = util.Iterator(board)
it.start()

try:
    while True:
        # Gradually increase the LED brightness from 0 to 255
        for brightness in range(256):
            led_pin.write(brightness / 255.0)  # Set LED brightness (0 to 1.0 scale)

        # Gradually decrease the LED brightness from 255 to 0
        for brightness in range(255, -1, -1):
            led_pin.write(brightness / 255.0)  # Set LED brightness (0 to 1.0 scale)

except KeyboardInterrupt:
    # Handle the program interruption by the user (Ctrl+C)
    print("Program interrupted by user.")

finally:
    # Safely exit the program and close the connection to the Arduino
    board.exit()

Steps to Run the Python Code

Connect your Arduino to your computer and note the COM port (replace 'COM8' in the code with your port).
Install the PyFirmata library in Python by running pip install pyfirmata in the terminal.
Save the code to a Python file and run it using python your_script_name.py.

Expected Output

Console displays "Program interrupted by user." upon termination.
The LED brightness will fade in and out continuously until the program is stopped.

Troubleshooting Tips

If the LED does not light up, ensure the connections are correct and the resistor is used.
Check that the correct COM port is specified in the code.

Suggestions for Beginners

If you're new to Arduino and Python, start with basic projects like LED on/off control before attempting brightness control. Familiarity with PyFirmata basics will help with troubleshooting.

Recommended Book for Learning Arduino

Arduino Programming for Absolute Beginners – This book offers simple, step-by-step Arduino projects that are ideal for building a solid foundation in Arduino programming and electronics.

For more free tutorials and Arduino projects, visit MechatronicsLab.net for resources on Arduino, ESP32, and more.