Vehicle Speed Sensor *Input*

Projects General Guidance
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Howdy folks, it's been a long, long time since I played with Arduinos/hardware solutions to software problems, so first and foremost, please be patient with me and consider me a rookie. I'm not new to programming, but it's been a long time since I did hardware interaction.

I'm aware of a myriad (1) of related prior posts (I could easily link more...), and at this point, my head is spinning.

Root of the project/problem:

I have a vehicle speed sensor ("VSS", pretty sure it's a hall effect sensor) that outputs a TON of square waves (min just over 0V, max something like 2.7v).

Like thousands of them a second (eg measure the wave frequency in microseconds). When it's linked directly to the speedometer, the speedo reads wrong. And not just a couple MPH off. We're talking orders of magnitude wrong.

I'm aware of Tim Toolman's similar project; in fact, I hope to leverage his code to output the (more) correct MPH.

What I have no damn idea what I'm doing for: VSS input. Specifically, I need a way to read in the VSS signal, and then once I am successfully doing so, do whatever sort of maths I need to, in order to re-translate it into a more accurate reading.

Seeing a LOT of conflicting information on that which makes my head hurt (again, been out of the game a long time). Some people use the TimerOne library (as Tim above does); but doesn't that interfere with above output, and it's doing "too much work" for one board (I've heard this a few times)? Some people do it all with interrupts (ughhhh, but if I have to), and if that's the case, how does THAT play with output...

I feel very lost and confused as to where to even start with this input problem.

Any and all advice (and sample code) would be greatly appreciated.

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Please post a link to the data sheet of the hall sensor.
Please tell which Arduino You are using.
Please post the code, autoformatted in the IDE and use code tags, the </> symbol, when pasting.

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I don't have a data sheet of the sensor. Just some scope readings.

I bigger picture want to be able to figure out how to read in that stuff myself and do something useful. I just want somewhere to start.

I'm using an Arduino Uno from like...at least 7 years ago, and I have a handful of Nanos I eventually will switch to that are about the same age.

There's all the code I have to-date that definitely works.

4

Does the sensor have a brand name and part number? Can you post a picture? Hall sensors are switched by magnets passing near them, how many magnets are on the wheel you are trying to read?

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But what is it connected to that is moving so fast and how is it connected to that thing.

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A Honda Civic.

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But what is it connected to that is moving so fast and how is it connected to that thing.

Reply

cgordini
34m

Paul_KD7HB:
But what is it connected to that is moving so fast and how is it connected to that thing.
A Honda Civic.
`l like your spirit. The Hall effect sensor, when energized, provides a reference. Useful data occurs then a magnet passes nearby and disturbs the reference signal. Those disturbances are what you want to count. Some magnets maybe mounted on a wheel (eg bicycle) or a driveshaft, (some cars). Nice graphics at What is Hall Effect and How Hall Effect Sensors Work - YouTube

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Show the sensor specs.
Values for digital out doesn't seem correct.
You might be trying to apply the wrong type of hall sensor.

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