neopixel-rpi.py

def uint32(x):
    if x & 0x8000000:
        x = x - 0xffffffff - 1
    return x

def byte2pwm(b):
    bits = "{:08b}".format(b)
    data = 0
    for c in bits:
        data = (data << 4) | (0b1000 if c == '0' else 0b1110)
    return data

def neopixel_pwm(p, l):
    p.active(False)
    p.fifo_clear()
    for i in l:
        p.fifo_queue(uint32(byte2pwm(i)))
    p.fifo_queue(0)
    p.active(True)

from machine import Clock, PWM, Pin
import time

Clock(Clock.PWM, enable=False, source=Clock.OSC, divi=5, divf=0, mash=0)
Clock(Clock.PWM, enable=True)
p = PWM(Pin(18), mode=PWM.MODE_SERIALIZER, active=0, tick_hz=3200000, duty_ticks=0, period=32, ms=PWM.MS_ENABLE, use_fifo=1, fifo_repeat=1)
neopixel_pwm(p,[50,0,0,0,50,0,0,0,50,25,25,0,0,25,25])