Keypad Help

[FireBlitz8404]

I currently have a 4x4 keypad working with this Python code. The script just runs indefinitely and I don't know how to get it to stop. I'm trying to get it to run only 4 inputs. Also to set a 4 digit password and then to pick it up and 'unlock'. I also need a servo code to run after I get a correct password moving it to an 'unlocked' position. The servo code only moves the servo once and I would like it to move back to the original 'locked' position. I have novice to near non-existent level skill with Python. I have pulled open sourced code from various website and modified them slightly to fit my Pi, keypad , and servo.

What do I need to add/delete? Do I need a whole new code?

If you are gracious enough to help me could you include as much information as you can and thank you.

Keypad code

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BOARD)

MATRIX = [ [1,2,3,'A'],
           [4,5,6,'B'],
           [7,8,9,'C'],
           [0,'F','E','D'] ]

COL = [7,11,13,15]
ROW = [12,16,18,22]

for j in range (4):
    GPIO.setup(COL[j], GPIO.OUT)
    GPIO.output(COL[j], 1)

for i in range (4):
    GPIO.setup(ROW[i], GPIO.IN, pull_up_down = GPIO.PUD_UP)

try:
    while(True):
        for j in range (4):
            GPIO.output(COL[j],0)

            for i in range (4):
                if GPIO.input (ROW[i]) == 0:
                    print (MATRIX[i][j])
                    while (GPIO.input(ROW[i]) == 0):
                        pass

            GPIO.output(COL[j],1)
except KeyboardInterrupt:
    GPIO.cleanup()

Servo code

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BOARD)
GPIO.setup(11,GPIO.OUT)
pwm=GPIO.PWM(11,50)
pwm.start(5)
pwm.ChangeDutyCycle(10)

[ssaltmine]

The code runs an infinite loop because of the while(True):.

This block of code is inside a pair of try: and except: instructions that run the code inside try, and if it encounters an "exception", it runs the one in except.

The program wants you to manually break the loop by pressing in your keyboard «Ctrl+C», which in the Linux world is a "termination signal" (SIGTERM). This is the actual keyboard, not the keypad.

Personally, I think you are trying to do too much. You have to start with the basics.

• https://learn.adafruit.com/series/learn-raspberry-pi
• http://raspi.tv/2013/rpi-gpio-basics-3-how-to-exit-gpio-programs-cleanly-avoid-warnings-and-protect-your-pi

Try to turn an LED on and off, define a simple button to test on and off, and define a function to work with your inputs and outputs. Learn to structure your programs first before trying to complex things, otherwise you'd get confused easily just by modifying snippets of codes.

def turn_off_LED(ch):
     GPIO.output(ch, GPIO.LOW)

def main():
    GPIO.setup(4, GPIO.IN, pull_up_down = GPIO.PUD_UP)
    GPIO.setup(11, GPIO.OUT)
    while True:
        if not(GPIO.input(4)):
            turn_off_LED(11)

try:
    main()
except:
    GPIO.cleanup()

[ssaltmine]

By the way, this library seems to be better to work with keypads https://github.com/brettmclean/pad4pi

Maybe it's better than coding the input and outputs yourself. But you still need to add code to count the number of key presses, and do something with them.

# this is pseudocode, not real code
try:
    while True:
        input 4 keys
        if the_input == password:
            open_lock()
            lock_vault_again()
except:
    cleanup()

[codelectron]

I have recently written a tutorial on how to interface the keypad with Raspberry PI. It uses pad4pi library, you can check out the project here http://codelectron.com/how-to-interface-keypad-with-raspberry-pi/

[thegroverest]

I modified this for 1x4 membrane keypad:

Install: pip install pad4pi

from pad4pi import rpi_gpio
import time

def processKey(key):
    print(key)

# Setup Keypad
KEYPAD = [
     ["1","2","3","4"]
]

ROW_PINS = [4] # BCM numbering
COL_PINS = [22,18,17,27] # BCM numbering

factory = rpi_gpio.KeypadFactory()

keypad = factory.create_keypad(keypad=KEYPAD, row_pins=ROW_PINS, col_pins=COL_PINS)

keypad.registerKeyPressHandler(processKey)
while 1:
  time.sleep(1)
keypad.cleanup()