Arduino Speedometer Using Hall Sensor and Magnet

by Zachary Lee

Arduino Speedometer Using Hall Sensor and Magnet

Have you ever wondered how a speedometer works? In this tutorial, we will show you how to build your own speedometer by measuring the magnetic pulses generated by a disc magnet located on a spinning wheel.

MATERIALS 

HARDWARE: 

SOFTWARE:

Step 1: Connections

  • Connect the Wireling TinyShield to the TinyScreen+.
  • Use the long 5-pin Wireling cable to connect the Hall-Effect Sensor to Port 0 on the Wireling TinyShield.
  • Connect the TinyScreen+ to your computer via the micro USB cable.

Step 2: Software

  • Open your Arduino IDE and select the TinyScreen+ from Tools -> Board.
    • Confirm that you are connected to the correct port. Navigate to Tools -> Port and select the port that contains “TinyScreen+.” The port number may vary.
     

      Step 3: The Code

      • Please download the code and required dependencies from the above Software section.
      • Note that you will most likely need to modify some of the constant parameters located at the beginning of the program:
      • The constant Boolean value USE_MPH allows you to choose between the English and metric systems for both the WHEEL_DIAMETER input and the speed output.
      • Make sure that you set the WHEEL_DIAMETER parameter as it is essential to produce accurate results. Unlike store bought speedometers made for a range of wheel sizes, you will be able to specify an exact value. Be sure to set WHEEL_DIAMETER  to the overall diameter of your wheel and tire combination.
      • RPM_SAMPLE_PERIOD allows you to control how far into the past the program includes sensor readings. Feel free to experiment with how this value impacts your results.
      • Once you have modified these parameters, upload the code to the TinyScreen+ using the upload button on the top left corner of the Arduino IDE interface. (pictured below)

           

       Step 4: Hardware

      • In order to measure the speed, it is necessary to place the disc magnet somewhere on a rotating wheel. On bicycles, a common location is on the spokes. We attached ours on a screw protruding from the wheel of a scooter. If there are no magnetic surfaces, you may need to tape or glue the magnet in place. Do not place the disc magnet on a rim if you have brake pads.
      • The Hall Sensor needs to be placed somewhere on the frame of the vehicle. Make sure to mount the sensor in such a way that the magnet will come very close to the front with every rotation. A strong magnet will enable distances of 5-6 inches, while a weak magnet may need to be within 2 inches or less.
      • Mount the TinyScreen+ wherever you prefer the viewing angle.

      That’s all there is to it! We hope you enjoyed this simple speedometer project!

      CONTACT US

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      Thanks for making with us!

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