import time
from machine import Pin

row_idx = [0, 1, 2, 3]
col_idx = [15, 14, 13, 12]

row_pins = []
col_pins = []

for i in range(4):
    row_pins.append(Pin(row_idx[i], Pin.OUT, Pin.PULL_DOWN))
for i in range(4):
    col_pins.append(Pin(col_idx[i], Pin.IN, Pin.PULL_DOWN))

print(row_pins)
print(col_pins)
symbol_table = [['1', '2', '3', 'A'], ['4', '5', '6', 'B'], ['7', '8', '9', 'C'], ['*', '0', '#', 'D']]


def key_scan():
    for r in range(4):
        row_pins[r].high()
        for c in range(4):
            if col_pins[c].value()==1:
                print(symbol_table[r][c])
        row_pins[r].low()

while True:
    key_scan()
    time.sleep(0.13)