matrix.py

from time import *
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BOARD) # Use physical layout as reference pins

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

ROW = [13, 15, 19, 21]
COL = [12, 16, 18, 22]

GLED = 7    # Green LED
RLED = 11   # Red LED

# Setup LEDs
GPIO.setup(GLED, GPIO.OUT)
GPIO.setup(RLED, GPIO.OUT)
GPIO.output(GLED, False)
GPIO.output(RLED, False)

# Setup Matrix modes
for j in range(4):
    GPIO.setup(COL[j], GPIO.OUT)
    GPIO.output(COL[j], 1)
    print(COL[j])
for i in range(4):
    GPIO.setup(ROW[i], GPIO.IN, pull_up_down = GPIO.PUD_UP)
    print(ROW[i])

inputpassword = ""
password = "2938"

try:
    # Keep checking for keyboard events
    while(True):
        for j in range(4):
            GPIO.output(COL[j], 0)
            for i in range(4):
                if GPIO.input(ROW[i]) is 0:
                    key = MATRIX[i][j]
                    print(MATRIX[i][j])
                    
                    if type(key) is int:
                        # Do stuff:
                        
                        # Blink green LED once:
                        
                    else:
                        if key is "D":
                            # Do stuff:
                            
                            # Blink red LED once:
                            
                    # When length is same as password's:
                    if (exp):
                        # Check for equality:
                        if (exp):
                            # Make green light solid for 10 seconds:
                            
                        else:
                            # Make red light solid for 10 seconds:
                            
                        # After that, clear inputpassword and reset lightså:
                        
                    while GPIO.input(ROW[i]) is 0:
                        pass
            GPIO.output(COL[j], 1)
except KeyboardInterrupt:
    GPIO.cleanup()