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4.1.7 Counting Device¶

Introduction¶

Here we will make a number-displaying counter system, consisting of a PIR sensor and a 4-digit segment display. When the PIR detects that someone is passing by, the number on the 4-digit segment display will add 1. You can use this counter to count the number of people walking through the passageway.

Required Components¶

In this project, we need the following components.

../_images/list_Counting_Device1.png ../_images/list_Counting_Device2.png

It’s definitely convenient to buy a whole kit, here’s the link:

Name

ITEMS IN THIS KIT

LINK

Raphael Kit

337

Raphael Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION

PURCHASE LINK

GPIO Extension Board

BUY

Breadboard

BUY

Jumper Wires

BUY

Resistor

BUY

4-Digit 7-Segment Display

-

74HC595

BUY

PIR Motion Sensor Module

-

Schematic Diagram¶

T-Board Name

physical

wiringPi

BCM

GPIO17

Pin 11

0

17

GPIO27

Pin 13

2

27

GPIO22

Pin 15

3

22

SPIMOSI

Pin 19

12

10

GPIO18

Pin 12

1

18

GPIO23

Pin 16

4

23

GPIO24

Pin 18

5

24

GPIO26

Pin 37

25

26

../_images/Schematic_three_one1.png

Experimental Procedures¶

Step 1: Build the circuit.

../_images/image235.png

Step 2: Go to the folder of the code.

cd ~/raphael-kit/python/

Step 3: Run the executable file.

sudo python3 4.1.7_CountingDevice.py

After the code runs, when the PIR detects that someone is passing by, the number on the 4-digit segment display will add 1.

There are two potentiometers on the PIR module: one is to adjust sensitivity and the other is to adjust the detection distance. To make the PIR module work better, you You need to turn both of them counterclockwise to the end.

../_images/PIR_TTE.png

Code

Note

You can Modify/Reset/Copy/Run/Stop the code below. But before that, you need to go to source code path like raphael-kit/python. After modifying the code, you can run it directly to see the effect.

#!/usr/bin/env python3
import RPi.GPIO as GPIO
import time

sensorPin = 26

SDI = 24
RCLK = 23
SRCLK = 18

placePin = (10, 22, 27, 17)
number = (0xc0, 0xf9, 0xa4, 0xb0, 0x99, 0x92, 0x82, 0xf8, 0x80, 0x90)

counter = 0

def clearDisplay():
    for i in range(8):
        GPIO.output(SDI, 1)
        GPIO.output(SRCLK, GPIO.HIGH)
        GPIO.output(SRCLK, GPIO.LOW)
    GPIO.output(RCLK, GPIO.HIGH)
    GPIO.output(RCLK, GPIO.LOW)

def hc595_shift(data):
    for i in range(8):
        GPIO.output(SDI, 0x80 & (data << i))
        GPIO.output(SRCLK, GPIO.HIGH)
        GPIO.output(SRCLK, GPIO.LOW)
    GPIO.output(RCLK, GPIO.HIGH)
    GPIO.output(RCLK, GPIO.LOW)

def pickDigit(digit):
    for i in placePin:
        GPIO.output(i,GPIO.LOW)
    GPIO.output(placePin[digit], GPIO.HIGH)

def display():
    global counter
    clearDisplay()
    pickDigit(0)
    hc595_shift(number[counter % 10])

    clearDisplay()
    pickDigit(1)
    hc595_shift(number[counter % 100//10])

    clearDisplay()
    pickDigit(2)
    hc595_shift(number[counter % 1000//100])

    clearDisplay()
    pickDigit(3)
    hc595_shift(number[counter % 10000//1000])

def loop():
    global counter
    currentState = 0
    lastState = 0
    while True:
        display()
        currentState=GPIO.input(sensorPin)
        if (currentState == 0) and (lastState == 1):
            counter +=1
        lastState=currentState

def setup():
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(SDI, GPIO.OUT)
    GPIO.setup(RCLK, GPIO.OUT)
    GPIO.setup(SRCLK, GPIO.OUT)
    for i in placePin:
        GPIO.setup(i, GPIO.OUT)
    GPIO.setup(sensorPin, GPIO.IN)

def destroy():   # When "Ctrl+C" is pressed, the function is executed.
    GPIO.cleanup()

if __name__ == '__main__':  # Program starting from here
    setup()
    try:
        loop()
    except KeyboardInterrupt:
        destroy()

Code Explanation

Based on 1.1.5 4-Digit 7-Segment Display, this project adds PIR module to change the automatic counting into count detecting. When the PIR detects that someone is passing by, the number on the 4-digit segment display will add 1.

def display():
    global counter
    clearDisplay()
    pickDigit(0)
    hc595_shift(number[counter % 10])

    clearDisplay()
    pickDigit(1)
    hc595_shift(number[counter % 100//10])

    clearDisplay()
    pickDigit(2)
    hc595_shift(number[counter % 1000//100])

    clearDisplay()
    pickDigit(3)
    hc595_shift(number[counter % 10000//1000])

First, start the fourth segment display, write the single-digit number. Then start the third segment display, and type in the tens digit; after that, start the second and the first segment display respectively, and write the hundreds and thousands digits respectively. Because the refreshing speed is very fast, we see a complete four-digit display.

def loop():
global counter
    currentState = 0
    lastState = 0
    while True:
        display()
        currentState=GPIO.input(sensorPin)
        if (currentState == 0) and (lastState == 1):
            counter +=1
        lastState=currentState

This is the main function: display the number on the 4-digit segment display and read the PIR value. When the PIR detects that someone is passing by, the number on the 4-digit segment display will add 1.

Phenomenon Picture¶

../_images/image236.jpeg