from machine import Pin
from time import sleep

led_bar_pins = [21, 19, 18, 5, 17, 16, 4, 0, 2, 15]
led_bar = [Pin(led_bar_pins[i], Pin.OUT) for i in range(10)]

def sub_led_bar():
    for pin in led_bar:
        pin.on()  
        sleep(0.05)  
        pin.off()  

    for pin in reversed(led_bar): 
        pin.on()  
        sleep(0.05)  
        pin.off()  

while True:
    sub_led_bar()

#it shows the led bar moving from top to bottom according to the order of red, yellow, and green
#each delay occurs within 0.05 seconds