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.. _4.1.7_py_pi5:

4.1.4 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.

.. image:: ../python_pi5/img/4.1.7_counting_device_list_1.png
    :align: center

.. image:: ../python_pi5/img/4.1.7_counting_device_list_2.png
    :align: center

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

.. list-table::
    :widths: 20 20 20
    :header-rows: 1

    *   - Name	
        - ITEMS IN THIS KIT
        - LINK
    *   - Raphael Kit
        - 337
        - |link_Raphael_kit|

You can also buy them separately from the links below.

.. list-table::
    :widths: 30 20
    :header-rows: 1

    *   - COMPONENT INTRODUCTION
        - PURCHASE LINK

    *   - :ref:`cpn_gpio_board`
        - |link_gpio_board_buy|
    *   - :ref:`cpn_breadboard`
        - |link_breadboard_buy|
    *   - :ref:`cpn_wires`
        - |link_wires_buy|
    *   - :ref:`cpn_resistor`
        - |link_resistor_buy|
    *   - :ref:`cpn_4_digit`
        - \-
    *   - :ref:`cpn_74hc595`
        - |link_74hc595_buy|
    *   - :ref:`cpn_pir`
        - \-


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
============ ======== ======== ===

.. image:: ../python_pi5/img/4.1.7_counting_device_schematic.png
   :align: center

Experimental Procedures
-----------------------------

**Step 1**: Build the circuit.

.. image:: ../python_pi5/img/4.1.7_counting_device_circuit.png


**Step 2**: Go to the folder of the code.

.. raw:: html

   <run></run>

.. code-block::

    cd ~/raphael-kit/python-pi5

**Step 3**: Run the executable file.

.. raw:: html

   <run></run>

.. code-block::

    sudo python3 4.1.7_CountingDevice_zero.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.

.. image:: ../python_pi5/img/4.1.7_PIR_TTE.png
    :width: 400
    :align: center

.. warning::

    If there is an error prompt  ``RuntimeError: Cannot determine SOC peripheral base address``, please refer to :ref:`faq_soc` 

**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-pi5``. After modifying the code, you can run it directly to see the effect.

.. raw:: html

    <run></run>

.. code-block:: python

   #!/usr/bin/env python3
   from gpiozero import OutputDevice, MotionSensor

   # Initialize PIR motion sensor on GPIO 26
   pir = MotionSensor(26)

   # Initialize shift register pins
   SDI = OutputDevice(24)    # Serial Data Input
   RCLK = OutputDevice(23)   # Register Clock Input
   SRCLK = OutputDevice(18)  # Shift Register Clock Input

   # Initialize 7-segment display pins
   placePin = [OutputDevice(pin) for pin in (10, 22, 27, 17)]

   # Define digit codes for 7-segment display
   number = (0xc0, 0xf9, 0xa4, 0xb0, 0x99, 0x92, 0x82, 0xf8, 0x80, 0x90)

   # Counter for the displayed number
   counter = 0

   def clearDisplay():
       # Clears the display by setting all segments off
       for _ in range(8):
           SDI.on()
           SRCLK.on()
           SRCLK.off()
       RCLK.on()
       RCLK.off()

   def hc595_shift(data):
       # Shifts data into the 74HC595 shift register
       for i in range(8):
           SDI.value = 0x80 & (data << i)
           SRCLK.on()
           SRCLK.off()
       RCLK.on()
       RCLK.off()

   def pickDigit(digit):
       # Activates a specific digit of the 7-segment display
       for pin in placePin:
           pin.off()
       placePin[digit].on()

   def display():
       # Updates the display with the current counter value
       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():
       # Main loop to update display and check for motion
       global counter
       currentState = 0
       lastState = 0
       while True:
           display()
           currentState = 1 if pir.motion_detected else 0
           if currentState == 1 and lastState == 0:
               counter += 1
           lastState = currentState

   try:
       loop()
   except KeyboardInterrupt:
       # Turn off all pins when the script is interrupted
       SDI.off()
       SRCLK.off()
       RCLK.off()
       pass


**Code Explanation**

#. This line imports the ``OutputDevice`` and ``MotionSensor`` classes from the ``gpiozero`` library. ``OutputDevice`` can be an LED, motor, or any device that you want to control as an output. The ``MotionSensor`` is typically a PIR (Passive Infrared) sensor used to detect motion.

   .. code-block:: python

       #!/usr/bin/env python3
       from gpiozero import OutputDevice, MotionSensor

#. Initializes the PIR motion sensor connected to GPIO pin 26.

   .. code-block:: python

       # Initialize PIR motion sensor on GPIO 26
       pir = MotionSensor(26)

#. Initializes GPIO pins connected to the shift register's Serial Data Input (SDI), Register Clock Input (RCLK), and Shift Register Clock Input (SRCLK).

   .. code-block:: python

       # Initialize shift register pins
       SDI = OutputDevice(24)    # Serial Data Input
       RCLK = OutputDevice(23)   # Register Clock Input
       SRCLK = OutputDevice(18)  # Shift Register Clock Input

#. Initializes the pins for each digit of the 7-segment display and defines the binary codes for displaying numbers 0-9.

   .. code-block:: python

       # Initialize 7-segment display pins
       placePin = [OutputDevice(pin) for pin in (10, 22, 27, 17)]

       # Define digit codes for 7-segment display
       number = (0xc0, 0xf9, 0xa4, 0xb0, 0x99, 0x92, 0x82, 0xf8, 0x80, 0x90)

#. Clears the 7-segment display by setting all segments off before displaying the next digit.

   .. code-block:: python

       def clearDisplay():
           # Clears the display by setting all segments off
           for _ in range(8):
               SDI.on()
               SRCLK.on()
               SRCLK.off()
           RCLK.on()
           RCLK.off()

#. Shifts a byte of data into the 74HC595 shift register, controlling the display segments.

   .. code-block:: python

       def hc595_shift(data):
           # Shifts data into the 74HC595 shift register
           for i in range(8):
               SDI.value = 0x80 & (data << i)
               SRCLK.on()
               SRCLK.off()
           RCLK.on()
           RCLK.off()

#. Selects which digit of the 7-segment display to activate. Each digit is controlled by a separate GPIO pin.

   .. code-block:: python

       def pickDigit(digit):
           # Activates a specific digit of the 7-segment display
           for pin in placePin:
               pin.off()
           placePin[digit].on()

#. Initiate the display for the unit digit first, followed by activating the display for the tens digit. Subsequently, engage the displays for the hundreds and thousands digits in order. This rapid succession of activations creates the illusion of a continuous four-digit display.

   .. code-block:: python

       def display():
           # Updates the display with the current counter value
           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])

#. Defines the main loop where the display is continuously updated, and the PIR sensor's state is checked. If motion is detected, the counter is incremented.

   .. code-block:: python

       def loop():
           # Main loop to update display and check for motion
           global counter
           currentState = 0
           lastState = 0
           while True:
               display()
               currentState = 1 if pir.motion_detected else 0
               if currentState == 1 and lastState == 0:
                   counter += 1
               lastState = currentState

#. Runs the main loop and ensures that the script can be interrupted with a keyboard command (Ctrl+C), turning off all pins for a clean exit.

   .. code-block:: python

       try:
           loop()
       except KeyboardInterrupt:
           # Turn off all pins when the script is interrupted
           SDI.off()
           SRCLK.off()
           RCLK.off()
           pass