from rp2 import PIO, StateMachine, asm_pio
from machine import Pin
import time
 
@asm_pio(set_init=PIO.OUT_LOW)
def led_quarter_brightness():
    set(pins, 0) [2]
    set(pins, 1)
 
@asm_pio(set_init=PIO.OUT_LOW)
def led_half_brightness():
    set(pins, 0)
    set(pins, 1)
 
@asm_pio(set_init=PIO.OUT_HIGH)
def led_full_brightness():
    set(pins, 1)
 
sm1 = StateMachine(1, led_quarter_brightness, freq=10000, set_base=Pin(25))
sm2 = StateMachine(2, led_half_brightness, freq=10000, set_base=Pin(25))
sm3 = StateMachine(3, led_full_brightness, freq=10000, set_base=Pin(25))
 
while(True):
    sm1.active(1)
    time.sleep(1)
    sm1.active(0)
 
    sm2.active(1)
    time.sleep(1)
    sm2.active(0)
 
    sm3.active(1)
    time.sleep(1)
    sm3.active(0)