from machine import Pin
from time import sleep

# Define rows and columns (adjust GPIOs if needed)
rows = [Pin(i, Pin.OUT) for i in (2,3,4,5)]    # R1, R2, R3, R4
cols = [Pin(i, Pin.IN, Pin.PULL_UP) for i in (6,7,8,9)]  # C1, C2, C3, C4

def scan_keypad():
    for r in range(4):
        rows[r].low()  # Pull this row LOW
        for c in range(4):
            if not cols[c].value():  # If this column is LOW, key is pressed
                rows[r].high()
                return r, c
        rows[r].high()
    return None

# Initialize all rows HIGH
for row in rows:
    row.value(1)

while True:
    key = scan_keypad()
    if key:
        print(f"Button pressed at [row, col]: {key}")
        while scan_keypad():  # Wait for key release (debounce)
            sleep(0.05)
    sleep(0.05)