# led chaser circuit 

from machine import Pin
from utime import sleep

t = 30 / 1000
t1 = 20 / 1000
t2 = 100 / 1000
t3 = 50 / 1000

pins = [Pin(i, Pin.OUT) for i in range(0, 20)]
# --------------------------------------------
def clear():
    for pin in pins:
        pin.off()
# --------------------------------------------
def effect_1():
    for i in range(len(pins)):
        if i + 2 < len(pins):
            pins[i].on()
            sleep(t1)
            pins[i + 1].on()
            sleep(t1)
            pins[i + 2].on()
            sleep(t1)
            pins[i].off()
            sleep(t1)
            pins[i + 1].off()
            sleep(t1)
    for i in range(len(pins)-1, 0, -1):
        if i - 2 >= 0:
            pins[i].on()
            sleep(t1)
            pins[i - 1].on()
            sleep(t1)
            pins[i - 2].on()
            sleep(t1)
            pins[i].off()
            sleep(t1)
            pins[i - 1].off()
            sleep(t1)
# --------------------------------------------
def effect_2():
    count = len(pins)-1
    for i in range(len(pins)):
        clear()
        pins[i].on()      # chaser 1
        pins[count].on()  # chaser 2
        count -= 1
        if count != 7:
            sleep(t2)

    for i in range(len(pins)-1, -1, -1):
        clear()
        pins[i].on()      # chaser 1
        pins[count].on()  # chaser 2
        count += 1
        if count != 8:
            sleep(t2)
# --------------------------------------------
def effect_3():
    for pin in pins:
        pin.on()
        sleep(t3)
    for pin in pins:
        pin.off()
        sleep(t3)
    for pin in reversed(pins):
        pin.on()
        sleep(t3)
    for pin in reversed(pins):
        pin.off()
        sleep(t3)
# --------------------------------------------
def effect_4():
    for j in range(len(pins)):
        pins[j].on()
        sleep(t2)
        pins[j].off()
    for k in range(len(pins)-1, -1, -1):
        pins[k].on()
        sleep(t2)
        pins[k].off()
# --------------------------------------------
def effect_5():
    for pin in range(len(pins)-1, 0, -1):
        pins[pin].on()
        sleep(t1)
        if pin + 1 < len(pins):
            pins[pin + 1].off()
            sleep(t1)
    
    for pin in range(len(pins)-1, 0, -1):
        if pin + 1 < len(pins):
            pins[pin + 1].on()
            sleep(t1)
            if pin + 2 < len(pins):
                pins[pin + 2].off()
                sleep(t1)
# --------------------------------------------
def effect_6():
    for j in range(len(pins)):
        pins[j].off()
        sleep(t)
        pins[j].on()
        sleep(t)
        if j - 2 >= 0:
            pins[j - 2].off()
            sleep(t)
            pins[j].on()
# --------------------------------------------
def effect_7():
    for j in range(len(pins)):
        pins[j].on()
        sleep(t)
        if j + 2 < len(pins):
            pins[j + 2].off()
            sleep(t)
# --------------------------------------------
while True:
    effect_1()
    effect_1()
    effect_2()
    effect_2()
    effect_3()
    effect_3()
    effect_4()
    effect_4()
    effect_5()
    effect_5()
    effect_6()
    effect_6()
    effect_7()
    effect_7()