import time
import utime
import machine
from machine import Pin


time.sleep(0.1) 

rows = [ Pin(i, Pin.OUT) for i in range(0, 4) ] 
cols = [ Pin(i, Pin.IN, Pin.PULL_DOWN) for i in range(18, 22) ]
leds = [ Pin(i, Pin.OUT) for i in range(4, 12)]

keys = [
  [ 1, 2, 3, 13 ],
  [ 4, 5, 6, 14 ],
  [ 7, 8, 9, 15 ],
  [ 10, 11, 12, 16 ]
]

def get_key():
    for row in range(4):
        for col in range(4):
            rows[row].high()
            key = None
            
            if cols[col].value() == 1:
                rows[row].low()
                time.sleep(0.1)
                return keys[row][col] 
        
        rows[row].low()

    return 16

while True:
    c = get_key()
    print(c)
    if c >= 1 and c <= 8:
        leds[c - 1].value(1)
    elif c == 15:
        for led in leds:
            led.off()

    time.sleep(0.1)