# Vehicle hall effect sensor (speed sensor)

Dear Users,
i have a problem about reading hall effect sensor, in my car , there is 60- 2 trigger wheel and how can i read sensor data i want to calculate wheel speed on lcd panel if you have sone example code please share me
thank you

What is a 60- 2 trigger wheel? - Scotty

Make sure what type of sensor you have. Most trigger wheels in my experience use Magnetic Variable Reluctance (MVR) sensors, not hall effect sensors. These sensors put out a sawtooth signal with an amplitude which increases with speed. In order to deal with the range of speeds that you'll see in a typical piston engine, you'll need to condition the signal to produce a clean 0-5V before you connect it to the Arduino input, otherwise you will have too low a voltage at low speeds, or risk an excessive voltage at higher speeds.

Once you have got a clean signal you just need to measure the frequency of the input signal. You can do this either using interrupts, or polling. Depending how high the frequency is that you're trying to measure, you might find that you can't poll it fast enough and in that case interrupts would be your only option.

There are two common algorithms for calculating frequency - counting the number of cycles in a given time interval, or measuring the duration of a single cycle. The first is more suitable for high frequencies, the second is more suitable for low frequencies. In your case the lowest frequency you want is probably several hundred Hertz and you will only want to update the display a few times a second, so the first approach would be most suitable.

trigger wheel is have 60 tooth and 2 space and explain is here http://www.bosch-motorsport.de/en-US/literature/en-US/Hall-Effect_Speed_Sensor_HA-D_90_Datasheet_51_en_2781699339.pdf (bottom of page)

sir i have 4 wheel speed sensor and speed is different between two sensor and i put new sensor on transmission output and reading real value so i will use hall effect sensor , for every revolotion, arduino will count 60 tooth and 2 space is for understand 1 rpm is complated.

That looks as if it's outputting a digital signal so it should be easy to interface to the Arduino. If you're just measuring the average speed and on't need to know the phase, you could ignore the effects of the missing teeth and just calculate the speed based on the actual number of teeth.