Category Archives: Raspberry Pi

In this lesson we add an audible alarm to our security system. I am connecting to a Bluetooth speaker, and then using the pygame library to play an alarm sound. The pygame library will play any .mp3 file, so search the internet and find a suitable alarm sound for your system. I amusing an air raid siren, and really like it! Below for your convenience is the code we develop in this video:

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BOARD)
PIRpin=12
GPIO.setup(PIRpin,GPIO.IN)
import LCD1602
import KPLIB
from time import sleep
import threading
myPad=KPLIB.keypad(retChar='D')
LCD1602.init(0x27,1)
myString=''
pwd='1234'

from pygame import mixer
mixer.init()
mixer.music.load('alarm.mp3')

def readKP():
    global myString
    while myString != '*':
        myString=myPad.readKeypad()
        sleep(.5)
readThread=threading.Thread(target=readKP,)
readThread.daemon=True
readThread.start()
while myString != '*':
    CMD=myString
    if CMD=='A'+pwd:
        LCD1602.write(0,0,'Armed          ')
        moveVal=GPIO.input(PIRpin)
        if moveVal==1:
            LCD1602.write(0,1,'Intruder Alert')
            mixer.music.play()
            sleep(10)
        if moveVal==0:
            LCD1602.write(0,1,'All Clear      ')
    if CMD=='B'+pwd:
        LCD1602.write(0,0,'UnArmed        ')
        LCD1602.write(0,1,'               ')
    if CMD=='C'+pwd:
        LCD1602.write(0,0,'Password?      ')
        LCD1602.write(0,1,'               ')
        while myString=='C'+pwd:
            pass
        pwd=myString
        LCD1602.write(0,0,pwd+'         ')
        sleep(2)
        LCD1602.write(0,0,'               ')
        LCD1602.clear()
sleep(1)
GPIO.cleanup()
LCD1602.clear()
print('GPIO Good to Go')

import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BOARD)

PIRpin=12

GPIO.setup(PIRpin,GPIO.IN)

import LCD1602

import KPLIB

from time import sleep

import threading

myPad=KPLIB.keypad(retChar='D')

LCD1602.init(0x27,1)

myString=''

pwd='1234'

from pygame import mixer

mixer.init()

mixer.music.load('alarm.mp3')

def readKP():

global myString

while myString != '*':

myString=myPad.readKeypad()

sleep(.5)

readThread=threading.Thread(target=readKP,)

readThread.daemon=True

readThread.start()

while myString != '*':

CMD=myString

if CMD=='A'+pwd:

LCD1602.write(0,0,'Armed ')

moveVal=GPIO.input(PIRpin)

if moveVal==1:

LCD1602.write(0,1,'Intruder Alert')

mixer.music.play()

sleep(10)

if moveVal==0:

LCD1602.write(0,1,'All Clear ')

if CMD=='B'+pwd:

LCD1602.write(0,0,'UnArmed ')

LCD1602.write(0,1,' ')

if CMD=='C'+pwd:

LCD1602.write(0,0,'Password? ')

LCD1602.write(0,1,' ')

while myString=='C'+pwd:

pass

pwd=myString

LCD1602.write(0,0,pwd+' ')

sleep(2)

LCD1602.write(0,0,' ')

LCD1602.clear()

sleep(1)

GPIO.cleanup()

LCD1602.clear()

print('GPIO Good to Go')

Raspberry Pi

Raspberry Pi LESSON 36: Motion Detection Alarm System With LCD and Keypad

November 10, 2022 admin

In this lesson we show the basic framework for an Alarm System with operator control through a keypad, and output to an LCD screen. We incorporate a PIR sensor to detect motion. In the next lesson we will add an audible alarm. For your convenience, the code developed in the above video is included below:

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BOARD)
PIRpin=12
GPIO.setup(PIRpin,GPIO.IN)
import LCD1602
import KPLIB
from time import sleep
import threading
myPad=KPLIB.keypad(retChar='D')
LCD1602.init(0x27,1)
myString=''
pwd='1234'
def readKP():
    global myString
    while myString != '*':
        myString=myPad.readKeypad()
        sleep(.5)
readThread=threading.Thread(target=readKP,)
readThread.daemon=True
readThread.start()
while myString != '*':
    CMD=myString
    if CMD=='A'+pwd:
        LCD1602.write(0,0,'Armed          ')
        moveVal=GPIO.input(PIRpin)
        if moveVal==1:
            LCD1602.write(0,1,'Intruder Alert')
        if moveVal==0:
            LCD1602.write(0,1,'All Clear      ')
    if CMD=='B'+pwd:
        LCD1602.write(0,0,'UnArmed        ')
        LCD1602.write(0,1,'               ')
    if CMD=='C'+pwd:
        LCD1602.write(0,0,'Password?      ')
        LCD1602.write(0,1,'               ')
        while myString=='C'+pwd:
            pass
        pwd=myString
        LCD1602.write(0,0,pwd+'         ')
        sleep(2)
        LCD1602.write(0,0,'               ')
        LCD1602.clear()
sleep(1)
GPIO.cleanup()
LCD1602.clear()
print('GPIO Good to Go')

import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BOARD)

PIRpin=12

GPIO.setup(PIRpin,GPIO.IN)

import LCD1602

import KPLIB

from time import sleep

import threading

myPad=KPLIB.keypad(retChar='D')

LCD1602.init(0x27,1)

myString=''

pwd='1234'

def readKP():

global myString

while myString != '*':

myString=myPad.readKeypad()

sleep(.5)

readThread=threading.Thread(target=readKP,)

readThread.daemon=True

readThread.start()

while myString != '*':

CMD=myString

if CMD=='A'+pwd:

LCD1602.write(0,0,'Armed ')

moveVal=GPIO.input(PIRpin)

if moveVal==1:

LCD1602.write(0,1,'Intruder Alert')

if moveVal==0:

LCD1602.write(0,1,'All Clear ')

if CMD=='B'+pwd:

LCD1602.write(0,0,'UnArmed ')

LCD1602.write(0,1,' ')

if CMD=='C'+pwd:

LCD1602.write(0,0,'Password? ')

LCD1602.write(0,1,' ')

while myString=='C'+pwd:

pass

pwd=myString

LCD1602.write(0,0,pwd+' ')

sleep(2)

LCD1602.write(0,0,' ')

LCD1602.clear()

sleep(1)

GPIO.cleanup()

LCD1602.clear()

print('GPIO Good to Go')

Python, Raspberry Pi

Library for Reading a 16 Button Keypad on the Raspberry Pi

October 27, 2022 admin

In this lesson we show you how to create a Python Class and Library that allows you to easily get user input on a Raspberry Pi from a 16 button keypad. This will allow very easy interaction with the keypad.

The Library Code which we develop in the video is presented below for your convenience:

class keypad:
    def __init__(self,rows=[11,13,15,29],columns=[31,33,35,37],keyLabels=[['1','2','3','A'],['4','5','6','B'],['7','8','9','C'],['*','0','#','D']],retChar='D'):
        import RPi.GPIO as GPIO
        self.rows=rows
        self.columns=columns
        self.retChar=retChar
        self.keyLabels=keyLabels
        GPIO.setmode(GPIO.BOARD)
        for i in rows:
            GPIO.setup(i,GPIO.OUT)
        for j in columns:
            GPIO.setup(j,GPIO.IN,pull_up_down=GPIO.PUD_DOWN)
    def readKeypad(self):
        from time import sleep
        import RPi.GPIO as GPIO
        keyStrokes=''
        noPress=True
        noPressOld=True
        while True:
            noPress=True
            for myRow in [0,1,2,3]:
                for myColumn in [0,1,2,3]:
                    GPIO.output(self.rows[myRow],GPIO.HIGH)
                    butVal=GPIO.input(self.columns[myColumn])
                    GPIO.output(self.rows[myRow],GPIO.LOW)
                    if butVal==1:
                        myChar=self.keyLabels[myRow][myColumn]
                        if myChar==self.retChar:
                            return keyStrokes
                        noPress=False
                    if butVal==1 and noPressOld==True and noPress==False:
                        keyStrokes=keyStrokes+myChar
            noPressOld=noPress
            sleep(.25)

class keypad:

def __init__(self,rows=[11,13,15,29],columns=[31,33,35,37],keyLabels=[['1','2','3','A'],['4','5','6','B'],['7','8','9','C'],['*','0','#','D']],retChar='D'):

import RPi.GPIO as GPIO

self.rows=rows

self.columns=columns

self.retChar=retChar

self.keyLabels=keyLabels

GPIO.setmode(GPIO.BOARD)

for i in rows:

GPIO.setup(i,GPIO.OUT)

for j in columns:

GPIO.setup(j,GPIO.IN,pull_up_down=GPIO.PUD_DOWN)

def readKeypad(self):

from time import sleep

import RPi.GPIO as GPIO

keyStrokes=''

noPress=True

noPressOld=True

while True:

noPress=True

for myRow in [0,1,2,3]:

for myColumn in [0,1,2,3]:

GPIO.output(self.rows[myRow],GPIO.HIGH)

butVal=GPIO.input(self.columns[myColumn])

GPIO.output(self.rows[myRow],GPIO.LOW)

if butVal==1:

myChar=self.keyLabels[myRow][myColumn]

if myChar==self.retChar:

return keyStrokes

noPress=False

if butVal==1 and noPressOld==True and noPress==False:

keyStrokes=keyStrokes+myChar

noPressOld=noPress

sleep(.25)

To use this code as a library, save it in the same folder as your python programs, and save it as KPLIB.py

import RPi.GPIO as GPIO
from KPLIB import keypad
myPad=keypad(retChar='A')
myString=myPad.readKeypad()
print(myString)
GPIO.cleanup()

import RPi.GPIO as GPIO

from KPLIB import keypad

myPad=keypad(retChar='A')

myString=myPad.readKeypad()

print(myString)

GPIO.cleanup()

This is a simple demo program that calls the library above, to receive input from the keypad.

Python, Raspberry Pi

Using a Photoresistor to Detect Light on the Raspberry Pi

September 29, 2022 admin

In this lesson we show how to detect light levels with a Raspberry Pi and a photoresistor. The photoresistor is connected in a voltage divider to the ADC0834 AD converter, which then connects to the Raspberry Pi. The schematic of the circuit is below:

Raspberry Pi

Creating a programmable Temperature Alarm with the Raspberry Pi

September 22, 2022 admin

In this video lesson we show how to create a programmable temperature alarm using the Raspberry Pi, the DHT11 sensor, the ADC0834, a potentiometer and a buzzer. The results are displayed on a LCD1602 LCD display with a i2c connection. The device operates in either program mode or monitor mode. Pressing the button puts you in programming mode. In this mode you turn the potentiometer until your desired set temperature is reached. Then pressing the button again will switch you to monitor mode. In monitor mode the current temperature and humidity are displayed on the LCD. When the temperature exceeds your setpoint, the buzzer will release an audible alarm. Below is the schematic for our build.

Technology Tutorials

Category Archives: Raspberry Pi

Raspberry Pi LESSON 37: Raspberry Pi Security System

Raspberry Pi LESSON 36: Motion Detection Alarm System With LCD and Keypad

Library for Reading a 16 Button Keypad on the Raspberry Pi

Using a Photoresistor to Detect Light on the Raspberry Pi

Creating a programmable Temperature Alarm with the Raspberry Pi

Making The World a Better Place One High Tech Project at a Time. Enjoy!