"""Part 5: print every key pressed."""

from machine import Pin
import time

KEYS = [
    ["1", "2", "3", "A"],
    ["4", "5", "6", "B"],
    ["7", "8", "9", "C"],
    ["*", "0", "#", "D"],
]

rows = [Pin(n, Pin.OUT, value=1) for n in (9, 8, 7, 6)]
columns = [Pin(n, Pin.IN, Pin.PULL_UP) for n in (13, 12, 11, 10)]


def pressed_key():
    found = None
    for row, labels in zip(rows, KEYS):
        row.value(0)
        for column, label in zip(columns, labels):
            if column.value() == 0:
                found = label
        row.value(1)
    return found


previous = None
while True:
    key = pressed_key()
    if key is not None and key != previous:
        print("Key:", key)
    previous = key
    time.sleep_ms(20)