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7.4 Passenger Counter

For large shopping malls, shopping centers, chain stores, airports, stations, museums, and public places such as exhibition halls, passenger traffic is an indispensable data.

In airports and stations, for example, the number of people needs to be strictly controlled to ensure safety and smooth flow. It is also possible to know when there are more visitors in shopping centers and chain stores, how many orders each user can generate, etc. As a result, we can analyze people’s consumption habits and increase turnover.

Passenger counters can help people understand the operation of these public places and organize their operations efficiently.

A simple passenger counter is created using a PIR sensor and a 4-digit 7-segment display.

Required Components

In this project, we need the following components.

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

Name	ITEMS IN THIS KIT	LINK
Kepler Kit	450+	Kepler Ultimate Kit

You can also buy them separately from the links below.

SN	COMPONENT	QUANTITY	LINK
1	Raspberry Pi Pico W	1	BUY
2	Micro USB Cable	1
3	Breadboard	1	BUY
4	Jumper Wires	Several	BUY
5	Resistor	4(220Ω)	BUY
6	4-Digit 7-Segment Display	1
7	74HC595	1	BUY
8	PIR Motion Sensor Module	1	BUY

Schematic

• This circuit is based on the 5.3 Time Counter with the addition of a PIR module.

• The PIR will send a high signal of about 2.8s long when someone passes by.

• The PIR module has two potentiometers: one adjusts sensitivity, the other adjusts detection distance. To make the PIR module work better, you need to turn both of them counterclockwise to the end.

  

Wiring

Code

Note

• Open the 7.4_passenger_counter.py file under the path of kepler-kit-main/micropython or copy this code into Thonny, then click “Run Current Script” or simply press F5 to run it.

• Don’t forget to click on the “MicroPython (Raspberry Pi Pico)” interpreter in the bottom right corner.

• For detailed tutorials, please refer to Open and Run Code Directly.

import machine
import time

# Initialize PIR sensor on pin 16, configured as an input
pir_sensor = machine.Pin(16, machine.Pin.IN)

# 7-segment display codes for digits 0-9, using hexadecimal to represent LED segments
SEGCODE = [0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f]

# Define pins for shift register communication (74HC595)
sdi = machine.Pin(18, machine.Pin.OUT)   # Serial Data Input
rclk = machine.Pin(19, machine.Pin.OUT)  # Register Clock (Latch)
srclk = machine.Pin(20, machine.Pin.OUT) # Shift Register Clock

# Initialize list to store 4 digit control pins
placePin = []

# Define control pins for each of the four digits (common anodes)
pin = [10,13,12,11] # Pin numbers for the 4-digit display
for i in range(4):
    placePin.append(None)  # Reserve space in list
    placePin[i] = machine.Pin(pin[i], machine.Pin.OUT)  # Initialize pin as output

# Initialize counter to keep track of detected motion events
count = 0

# Function to select which digit (0-3) to display by controlling the common anode pins
def pickDigit(digit):
    for i in range(4):
        placePin[i].value(1)  # Turn off all digits
    placePin[digit].value(0)  # Turn on the selected digit

# Function to clear the display by sending '0x00' to the shift register
def clearDisplay():
    hc595_shift(0x00)

# Function to send data to the shift register (74HC595)
def hc595_shift(dat):
    rclk.low()  # Pull latch low to prepare for data shifting
    time.sleep_us(200)  # Small delay for timing stability
    for bit in range(7, -1, -1):  # Loop through each bit (MSB first)
        srclk.low()  # Prepare to send the next bit
        time.sleep_us(200)
        value = 1 & (dat >> bit)  # Extract the current bit from the data
        sdi.value(value)  # Set the data line to the current bit value
        time.sleep_us(200)
        srclk.high()  # Pulse the shift clock to store the bit in the register
        time.sleep_us(200)
    time.sleep_us(200)
    rclk.high()  # Pulse the register clock to move the data to the output

# Interrupt handler for PIR sensor, triggered on motion detection (rising edge)
# Increments the motion count each time the sensor is triggered
def motion_detected(pin):
    global count
    count = count + 1  # Increment the count when motion is detected

# Set up an interrupt to detect motion using the PIR sensor
pir_sensor.irq(trigger=machine.Pin.IRQ_RISING, handler=motion_detected)

# Main loop to continuously update the 7-segment display with the current count
while True:
    # Update the first digit (units place)
    pickDigit(0)
    hc595_shift(SEGCODE[count % 10])

    # Update the second digit (tens place)
    pickDigit(1)
    hc595_shift(SEGCODE[count % 100 // 10])

    # Update the third digit (hundreds place)
    pickDigit(2)
    hc595_shift(SEGCODE[count % 1000 // 100])

    # Update the fourth digit (thousands place)
    pickDigit(3)
    hc595_shift(SEGCODE[count % 10000 // 1000])

When the code is run, the number on the 4-digit 7-segment display will be added by one if someone passes in front of the PIR module.