How to Wire and Code SK6812 RGBW LED Strips on Raspberry Pi

				
					# === RGBW led strip setup ===
LED_COUNT = 60        # LED quantity
LED_PIN = 18          # GPIO
LED_FREQ = 800000     # frequency
LED_DMA = 10          # DMA LED_CHANNEL
LED_BRIGHTNESS = 150  # LED_BRIGHTNESS(0-255)
LED_INVERT = False
LED_CHANNEL = 0
STRIP_TYPE = 0x18100800  # SK6812RGBW code

# format LED strip
strip = PixelStrip(
    LED_COUNT, LED_PIN, LED_FREQ, LED_DMA,
    LED_INVERT, LED_BRIGHTNESS, LED_CHANNEL,
    STRIP_TYPE
)
strip.begin()

# === RGBW color generation（revided）===
def wheel(pos):
    """generate logical RGBW value"""
    pos = 255 - pos
    if pos < 85:
        r, g, b = pos * 3, 255 - pos * 3, 0
    elif pos < 170:
        pos -= 85
        r, g, b = 255 - pos * 3, 0, pos * 3
    else:
        pos -= 170
        r, g, b = 0, pos * 3, 255 - pos * 3
    
    # ensure each channel is within 0-255
    r = max(0, min(255, r))
    g = max(0, min(255, g))
    b = max(0, min(255, b))
    w = 50  # fix white intensity
    
    # go back to logical 32bit value
    return (w << 24) | (r << 16) | (g << 8) | b

# === main effect ===
def rgbw_flow(speed_ms=20):
    """RGBW full color flowing effect（revised）"""
    step = 0
    try:
        while True:
            for i in range(LED_COUNT):
                hue = int((i * 256 / LED_COUNT) + step) % 256
                strip.setPixelColor(i, wheel(hue))
            
            strip.show()
            time.sleep(speed_ms / 1000.0)
            step += 1
    except KeyboardInterrupt:
        pass

# === escape safely ===
def signal_handler(sig, frame):
    print("\n close LED...")
    for i in range(LED_COUNT):
        strip.setPixelColor(i, 0)  # use 0 instead of Color(0,0,0,0)
    strip.show()
    sys.exit(0)

signal.signal(signal.SIGINT, signal_handler)

if __name__ == '__main__':
    print("RGBW addressable flowing start (Ctrl+Cstop)")
    rgbw_flow(speed_ms=25)