WS2801 ledstrip demo

ws2801ledstrip.py

# https://raspberrytips.nl/ws2801-ledstrip/
# Simple demo script for a WS2801/SPI-like addressable RGB LED lightstrip.

import time
import RPi.GPIO as GPIO
import Adafruit_WS2801
import Adafruit_GPIO.SPI as SPI

# Configure the count of pixels:
PIXEL_COUNT = 32

# Alternatively specify a hardware SPI connection on /dev/spidev0.0:
SPI_PORT   = 0
SPI_DEVICE = 0
pixels = Adafruit_WS2801.WS2801Pixels(PIXEL_COUNT, spi=SPI.SpiDev(SPI_PORT, SPI_DEVICE), gpio=GPIO)

# Define the wheel function to interpolate between different hues.
def wheel(pos):
    if pos < 85:
        return Adafruit_WS2801.RGB_to_color(pos * 3, 255 - pos * 3, 0)
    elif pos < 170:
        pos -= 85
        return Adafruit_WS2801.RGB_to_color(255 - pos * 3, 0, pos * 3)
    else:
        pos -= 170
        return Adafruit_WS2801.RGB_to_color(0, pos * 3, 255 - pos * 3)

def rainbow_cycle(pixels, wait=0.005):
    for j in range(256): # one cycle of all 256 colors in the wheel
        for i in range(pixels.count()):
            pixels.set_pixel(i, wheel(((i * 256 // pixels.count()) + j) % 256) )
        pixels.show()
        if wait > 0:
            time.sleep(wait)

def brightness_decrease(pixels, wait=0.01, step=1):
    for j in range(int(256 // step)):
        for i in range(pixels.count()):
            r, g, b = pixels.get_pixel_rgb(i)
            r = int(max(0, r - step))
            g = int(max(0, g - step))
            b = int(max(0, b - step))
            pixels.set_pixel(i, Adafruit_WS2801.RGB_to_color( r, g, b ))
        pixels.show()
        if wait > 0:
            time.sleep(wait)

if __name__ == "__main__":
    # Clear all the pixels to turn them off.
    pixels.clear()
    pixels.show()  # Make sure to call show() after changing any pixels!
    rainbow_cycle(pixels, wait=0.02)
    brightness_decrease(pixels)