from machine import Pin
from time import sleep

# Assign all LEDs
led1 = Pin(15, Pin.OUT)
led2 = Pin(14, Pin.OUT)
led3 = Pin(13, Pin.OUT)
led4 = Pin(12, Pin.OUT)

WAIT_TIME = 0.4  # time to wait between numbers

# main loop
while True:
    # 1 => 0001
    led4.value(0)
    led3.value(0)
    led2.value(0)
    led1.value(1)
    sleep(WAIT_TIME)

    # 2 => 0010
    led4.value(0)
    led3.value(0)
    led2.value(1)
    led1.value(0)
    sleep(WAIT_TIME)

    # 3 => 0011
    led4.value(0)
    led3.value(0)
    led2.value(1)
    led1.value(1)
    sleep(WAIT_TIME)

    # 4 => 0100
    led4.value(0)
    led3.value(1)
    led2.value(0)
    led1.value(0)
    sleep(WAIT_TIME)

    # 5 => 0101
    led4.value(0)
    led3.value(1)
    led2.value(0)
    led1.value(1)
    sleep(WAIT_TIME)

    # 6 => 0110
    led4.value(0)
    led3.value(1)
    led2.value(1)
    led1.value(0)
    sleep(WAIT_TIME)

    # 7 => 0111
    led4.value(0)
    led3.value(1)
    led2.value(1)
    led1.value(1)
    sleep(WAIT_TIME)

    # 8 => 1000
    led4.value(1)
    led3.value(0)
    led2.value(0)
    led1.value(0)
    sleep(WAIT_TIME)

    # 9 => 1001
    led4.value(1)
    led3.value(0)
    led2.value(0)
    led1.value(1)
    sleep(WAIT_TIME)

    # 10 => 1010
    led4.value(1)
    led3.value(0)
    led2.value(1)
    led1.value(0)
    sleep(WAIT_TIME)

    # 11 => 1011
    led4.value(1)
    led3.value(0)
    led2.value(1)
    led1.value(1)
    sleep(WAIT_TIME)

    # 12 => 1100
    led4.value(1)
    led3.value(1)
    led2.value(0)
    led1.value(0)
    sleep(WAIT_TIME)

    # 13 => 1101
    led4.value(1)
    led3.value(1)
    led2.value(0)
    led1.value(1)
    sleep(WAIT_TIME)

    # 14 => 1110
    led4.value(1)
    led3.value(1)
    led2.value(1)
    led1.value(0)
    sleep(WAIT_TIME)

    # 15 => 1111
    led4.value(1)
    led3.value(1)
    led2.value(1)
    led1.value(1)
    sleep(WAIT_TIME)

    # 0 => 0000
    led4.value(0)
    led3.value(0)
    led2.value(0)
    led1.value(0)
    sleep(WAIT_TIME)