Controlling RGB LEDs with the RGB_LED Class

The RGB_LED class in the RpiL library is designed to control an RGB LED using three GPIO pins. It provides methods for setting specific colors, cycling through a rainbow of colors, and turning the LED on or off.

Class Overview

The RGB_LED class requires three GPIO pin numbers as arguments: * red_pin - The GPIO pin connected to the red component of the RGB LED. * green_pin - The GPIO pin connected to the green component of the RGB LED. * blue_pin - The GPIO pin connected to the blue component of the RGB LED.

PWM (Pulse Width Modulation) is used to control the brightness of each color component of the LED.

Methods

  • set_color(hex_color)

    • Sets the RGB LED to a specific color based on a hex string (e.g., ‘#FF00FF’).

    • Converts the hex color into individual red, green, and blue components, and adjusts the PWM duty cycle accordingly.

  • rainbow_cycle(wait=0.05)

    • Starts a rainbow color cycling effect in a separate thread. The LED will continuously cycle through rainbow colors.

    • The wait parameter controls the speed of the color transitions (in seconds).

  • stop_rainbow_cycle()

    • Stops the rainbow color cycling effect and turns off the LED.

  • wheel(position=0)

    • A static method that generates a color based on the position in the 0-255 range. This creates a smooth rainbow effect.

    • position is an integer between 0 and 255 that determines the current color.

  • off()

    • Turns off the RGB LED by setting all PWM duty cycles to 0.

Example Usage

Here’s how you can use the RGB_LED class to control an RGB LED:

from RpiL import RGB_LED

# Initialize RGB LED with red pin on GPIO 17, green pin on GPIO 27, blue pin on GPIO 22
led = RGB_LED(red_pin=17, green_pin=27, blue_pin=22)

led.set_color('#FF00FF')  # Set color to purple
time.sleep(2)  # Keep LED on for 2 seconds

led.rainbow_cycle()  # Start rainbow effect
time.sleep(10)  # Run rainbow for 10 seconds
led.stop_rainbow_cycle()  # Stop rainbow effect

led.off()  # Turn off the LED

Notes

  • This class uses PWM to control the brightness of each color component of the RGB LED. The duty cycle (0-100) corresponds to the brightness of the LED.

  • To create a smooth color transition, the rainbow_cycle method cycles through a range of colors. The wheel method generates the appropriate RGB values for each position.

  • The set_color method accepts a hex string, which is a standard format for representing colors (e.g., ‘#FF00FF’ for purple).

Cleanup

The RGB_LED class automatically cleans up the GPIO pins when the object is deleted, ensuring proper release of the resources. If the rainbow cycle is running, it is also stopped before cleanup.