from machine import Pin
from time import sleep

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

linhas= [Pin(pinos, Pin.OUT) for pinos in (7,6,5,4)]
colunas= [Pin(pinos, Pin.IN, Pin.PULL_DOWN) for pinos in (3,2,1,0)]

def teclado():
    for i in range(4):
        for linha in linhas:
            linha.value(0)
        linhas[i].value(1)

        for x in range(4):
            if colunas[x].value() == 1:
                while colunas[x].value() == 1:
                    sleep(0.01)
                return teclas[i][x]

def ver_tecla():
    tecla= teclado()

    if tecla:
        print(f"a tecla presionada foi:{tecla}")

while True:
    ver_tecla()