# https://www.instructables.com/Respberry-Pi-Pico-W-NeoPixels-Experiments-With-Pro/

import time
import rp2
from machine import Pin

@rp2.asm_pio(set_init=rp2.PIO.OUT_LOW, out_shiftdir=rp2.PIO.SHIFT_LEFT)  

def neo_prog():
    pull()                       # osr <= 24 bits GRB
    set(x, 23)                   # x (bit counter) <= 23
    label("loop_pixel_bit")
    out(y, 1)                    # y <= left-most 1 bit of osr
    jmp(not_y, "bit_0")
    set(pins, 1).delay(13)       # 1: high (7 cycles)
    set(pins, 0).delay(9)        # 1: low (5 cycles)
    jmp("bit_end")
    label("bit_0")
    set(pins, 1).delay(5)        # 0: high (3 cycles)
    set(pins, 0).delay(17)       # 0: low (9 cycles)
    label("bit_end")
    jmp(x_dec, "loop_pixel_bit") # x is bit counter

sm = rp2.StateMachine(0, neo_prog, freq=20_000_000, set_base=Pin(12))
sm.active(1)

g = 0x55
r = 0x0F
b = 0x1F
grb = (g << 16) + (r << 8) + b
while(1):
    sm.put(grb << 8)
    time.sleep(0.1)