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Lesson 06: Hall Sensor Module

Note

The Raspberry Pi does not have analog input capabilities, so it needs a module like the PCF8591 ADC DAC Converter Module to read analog signals for processing.

In this lesson, we will learn how to use a Raspberry Pi to read from a hall sensor module. You will learn how to connect a photoresistor module to the PCF8591 for analog-to-digital conversion and monitor its output in real-time using Python. Additionally, you will explore reading analog values and interpreting them to detect the presence and type of magnetic poles.

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

Universal Maker Sensor Kit

94

Universal Maker Sensor Kit

You can also buy them separately from the links below.

Component Introduction

Purchase Link

Raspberry Pi 5

BUY

Hall Sensor Module

-

PCF8591 ADC DAC Converter Module

BUY

Breadboard

BUY

Wiring

../_images/Lesson_06_Hall_Sensor_Module_pi_bb.png

Code

import PCF8591 as ADC  # Import PCF8591 module
import time  # Import time for delay

ADC.setup(0x48)  # Initialize PCF8591 at address 0x48

try:
    while True:  # Continuously read and print
        sensor_value = ADC.read(1) # Read from hall sensor module at AIN1
        print(sensor_value,end="")  # Print the sensor raw data

        # Determine the polarity of the magnet
        if sensor_value >= 180:
            print(" - South pole detected")   # Determined as South pole.
        elif sensor_value <= 80:
            print(" - North pole detected")   # Determined as North pole.

        time.sleep(0.2)  # Wait for 0.2 seconds before the next read

except KeyboardInterrupt:
    print("Exit")  # Exit on CTRL+C

Code Analysis

  1. Import Libraries:

    import PCF8591 as ADC  # Import PCF8591 module
import time  # Import time for delay

    This imports necessary libraries. PCF8591 is used to interact with the ADC module, and time is for implementing delays in the loop.

  2. Initialize ADC Module:

    ADC.setup(0x48)  # Initialize PCF8591 at address 0x48

    Sets up the PCF8591 module. 0x48 is the I2C address of the PCF8591 module. This line prepares the Raspberry Pi to communicate with the module.

  3. Main Loop for Reading Sensor Data:

    try:
    while True:  # Continuously read and print
        sensor_value = ADC.read(1) # Read from hall sensor module at AIN1
        print(sensor_value, end="")  # Print the sensor raw data

    In this loop, sensor_value is read continuously from the Hall sensor (connected to AIN1 on the PCF8591). The print statement outputs the raw sensor data.

  4. Determine Magnet Polarity:

    # Determine the polarity of the magnet
if sensor_value >= 180:
    print(" - South pole detected")   # Determined as South pole.
elif sensor_value <= 80:
    print(" - North pole detected")   # Determined as North pole.

    Here, the code determines the polarity of the magnet. If sensor_value is 180 or higher, it is identified as the South pole. If it is 80 or lower, it is considered the North pole. You need to modify these two threshold values based on your actual measurement results.

    The Hall sensor module is equipped with a 49E linear Hall effect sensor, which can measure the polarity of the magnetic field’s north and south poles as well as the relative strength of the magnetic field. If you place a magnet’s south pole near the side marked with 49E (the side with text engraved on it), the value read by the code will increase linearly in proportion to the applied magnetic field strength. Conversely, if you place a north pole near this side, the value read by the code will decrease linearly in proportion to that magnetic field strength. For more details, please refer to Hall Sensor Module.

  5. Delay and Exception Handling:

    time.sleep(0.2)  # Wait for 0.2 seconds before the next read

except KeyboardInterrupt:
    print("Exit")  # Exit on CTRL+C

    time.sleep(0.2) creates a 0.2-second delay between each loop iteration to prevent excessive reading speed. The except block catches a keyboard interrupt (CTRL+C) to exit the program gracefully.