from machine import Pin
from time import sleep

led1=Pin(0,Pin.OUT)
led2=Pin(2,Pin.OUT)
led3=Pin(4,Pin.OUT)
led4=Pin(5,Pin.OUT)

def binarydisplay(decimalnumber):

    binarystring='{0:04b}'.format(decimalnumber)
    print(binarystring) #0000
    led1.value(int(binarystring[0]))
    led2.value(int(binarystring[1]))
    led3.value(int(binarystring[2]))
    led4.value(int(binarystring[3]))

while True:
    for i in range(0,16):
        binarydisplay(i)
        print("decimal value = ",i)
        sleep(2)