from machine import Pin
import time

# Define GPIO pins for 4 LEDs (adjust to your wiring)
led_pins = [10, 11, 12, 13]   # Example pins GP2–GP5
leds = [Pin(pin, Pin.OUT) for pin in led_pins]

def display_binary(value):
    """Show a 4-bit binary number on LEDs"""
    for i in range(4):
        bit = (value >> i) & 1
        leds[i].value(bit)

# Binary counter loop
counter = 0
while True:
    display_binary(counter)
    time.sleep(1)   # 1 second delay between counts
    counter = (counter + 1) % 16   # wrap around after 15