CIS_Final_Project

My final project for CIS2020: Fundamentals of Unix.

• Python code written on a Raspberry Pi 3B working with a breadboard and circuits in order to manipulate a sensor.
• This is a step-by-step instruction manual to create a working distance sensor with an intrusion detection system.
• The sensor will display the distance to the nearest object in meters and then will set off the 'alarm' (LED) when the object is closer than a defined amount of meters.

Let's Begin!

To make this project you will need:

• A raspberry pi (I used a Pi 3b)
  • HDMI cords and power cords depending on need
• Eight male-to-female jumper wires
• One button switch
• One breadboard
• One ultrasonic distance sensor
• One LED of your choosing (I used red)
• One 330 Ohms resistor
• One 570 Ohms resistor
• One 370 Ohms resistor

Warning!!

In order to make sure you don't damage your raspberry pi, you will need to disconnect if from all power before attempting the ciruits. Do not bend pins and do NOT forget about the resistors. The purpose of the resistors is to stop the LED and ultrasonic distance sensor from consuming too much power and overheating. Make sure your circuits are properly grounded as well.

Due to the fact that TinkerCad does not have a raspberry pi component, I have used a breadboard in its place. The breadboard on the left is the raspberry pi in this scenario.

Steps

1: Connect ultrasonic distance sensor

Connect the distance sensor just like this on the breadboard. The ground pin on the distance sensor is associated with the red jumper wire. That wire connects to the 6th pin on the pi, which is ground. The two resistors are combined to prevent the distance sensor from drawing too much power. I used the 330 Ohms resistor through the H2 and H6 pins on the breadboard. I have the 570 Ohmd resistor through H1 and H6. The trigger is connected via the green jumper wire in F3. The wire is then connected to the pi in pin 18, which is GPIO 24. The blue jumper wire is in F6 connects to pin 26 on the pi. This means Echo is GPIO 23. The white jumper wire needs to be connected from its spot on the breadboard (F4) to the 2nd pin on the pi, which is 5V. This gives the distance sensor power.

2: Connect LED

Imitate this set up on your breadboard. The LED is positioned with the Anode in D17, the cathode in D16. The red jumper wire is in C16 of the breadboard. It connects to the pi in pin 6, ground. The resistor is 370 Ohms. This stops the LED from drawing too much power. It is placed in C17 through C21. The yellow wire is in B21, next to the end of the resistor. This connects to pin 7 on the pi, that is gpio 4.

3: Connect Button

This is how the button should be set up. Make sure that your button is facing the exact direction displayed. If it is rotated then the button will not work. There should only be one hole between the legs towards the left like shown in the picture. The buttom jumper wire needs to be connected to GPIO 17 which is pin 11 on the Pi. The top jumper wire is connected to a ground pin, I used pin 39 on the Pi.

4: Time to Code!

from gpiozero import DistanceSensor, LED, Button
from time import sleep
from gpiozero.pins.pigpio import PiGPIOFactory

sensor = DistanceSensor(echo=23, trigger=24)
red = LED(4)
button = Button(17)
    
def up():
    global result
    result = False
    
def lighton():
    red.on()
    
def lightoff():
    red.off()
    
t = True

button.wait_for_press()
while t == True:
    print('Distance to nearest object is', sensor.distance * 100, 'm')
    sleep(1)
    red.off()
    if sensor.distance * 100 < 10.00:
        lighton()
        finald = sensor.distance
        t = False
        print('Intrusion detected at', finald *100, 'm')
        sleep(10)
red.off()

I used the python interpreter Thonny to write this. Although this file and code can be run in any python interpretor, I would suggest running it in Thonny. This block of code represents how to tell the pi to run the distance sensor and process the information. button.waitforpress() instructs the code to wait until the button is pressed until continuing on to the next set of code. You can change the distance that you wish to detect by changing the if line that sttes 'if sensor.distance * 100 < 10.00:' The 10.00 is the distance that we have told the pi to declare an intrusion at. red.off() at the end of the code instructs the LED to turn off when the program is over, this is due to the fact that the LED will remain on otherwise. If it is not turned off with that line of code, then a second attempt of running the code with the LED still on may produce a result where the LED doesn't trigger when an intrustion is detected.

5: Done!

If you have followed all of the steps correctly, you should have a working distance intrusion detector. If yours does not seem to work, I would suggest going through your inputs first to make sure the physical components are hooked up correctly. I would advise you to check that each input works and can be triggered before moving onto a second input. This reduces the chances of more issues arising or a lengthy search for one. Another thing to check is the resistors. Wrong resistors can cause a component to draw too little or too much power, preventing it from working. There are online guides that can help you calculate the resistance of four and five band resistors.

Thank you for reading!