test_rainbow.py

import board
import time
import neopixel
# light on only the first LED
#pixels=neopixel.NeoPixel(board.D18, 30)
#pixels[0]=(255,0,0)

num_pixels=16

pixel_pin=board.D18
ORDER=neopixel.GRB
pixels = neopixel.NeoPixel(pixel_pin, num_pixels, brightness=0.05,auto_write=False,pixel_order=ORDER)

def wheel(pos):
    if pos<0 or pos>255:
        r=g=b=0
    elif pos<85:
        r = int(pos*3)
        g=int(255-pos*3)
        b=0
    elif pos<170:
        pos -=85
        r=int(255-pos*3)
        g=0
        b=int(pos*3)
    else:
        pos -= 170
        r = 0
        g = int(pos*3)
        b=int(255-pos*3)
    return (r,g,b) if ORDER in (neopixel.RGB, neopixel.GRB) else (r,g,b,0)

def rainbow_cycle(wait):
    for j in range(255):
        for i in range(num_pixels):
            pixel_index=(i*256 //num_pixels)+j
            pixels[i]=wheel(pixel_index & 255)
        pixels.show()
        time.sleep(wait)

while True:
    rainbow_cycle(0.001)
    print(1)