from time import sleep_ms
from machine import Pin

ledcols = [0, 1, 2, 3, 4 , 5, 6, 7]
swcols = [8, 9, 10, 11, 12, 13, 14, 15]
rows = [18, 19, 20, 21]

row_pins = [ Pin(pin_name, mode=Pin.OUT, value = 0) for pin_name in rows ]
ledcol_pins = [ Pin(pin_name, mode=Pin.OUT, value = 1) for pin_name in ledcols ]
swcol_pins = [ Pin(pin_name, mode=Pin.IN, pull=Pin.PULL_DOWN) for pin_name in swcols ]

last_keys = set()

while True:
  current_keys = set()
  for current_row in range(len(row_pins)):
    for row_number, row in enumerate(row_pins):
      if row_number == current_row:
        row.high()
      else:
        row.low()
    for ledcol_number, ledcol in enumerate(ledcol_pins):
      for key in current_keys:
        if key == (current_row, ledcol_number):
          ledcol.low()
        ledcol.high()
    for swcol_number, swcol in enumerate(swcol_pins):
      if swcol.value() == 1:
        current_keys.add((current_row,swcol_number))

  if current_keys != last_keys:
    print("\nKeys changed")
    print("New keys = ", current_keys - last_keys)
    print("Released keys = ", last_keys - current_keys)
    for key in current_keys:
      keynum = key[0] * 8 + key[1]
      keyspot = 1 << keynum
      print("Current Key: {0} = 0b{1:b}".format(keynum, keyspot))
  last_keys = current_keys