from machine import Pin
import utime
 
# Connect Keypad pins as below
col_list=[16,17,18,19]
row_list=[20,21,22,26]
 
#Set rows pin as output
for x in range(0,4):
    row_list[x]=Pin(row_list[x], Pin.OUT)
    row_list[x].value(1)
 
#Set column as input
for x in range(0,4):
    col_list[x] = Pin(col_list[x], Pin.IN, Pin.PULL_UP)
 
# Create a map between keypad buttons and chars
key_map=[["D","#","0","*"],\
         ["C","9","8","7"],\
         ["B","6","5","4"],\
         ["A","3","2","1"]]
 
def Keypad4x4Read(cols,rows):
  for r in rows:
    r.value(0)
    result=[cols[0].value(),cols[1].value(),cols[2].value(),cols[3].value()]
    if min(result)==0:
      key=key_map[int(rows.index(r))][int(result.index(0))]
      r.value(1) # manages key keept pressed
      return(key)
    r.value(1)
 
# Start the main loop
print("--- Ready to get user inputs ---")
while True:
    key=Keypad4x4Read(col_list, row_list)
    if key != None:
      print("Pressed button: "+key)
      utime.sleep(0.3) # gives user enough time to release without having double inputs known as debounce