Wheel Speed Sensor Setup

ADU
1

I don’t know if it’s just me, but I’m not feeling like there are very clear instructions for setting up a wheel speed sensor to be used by the adu. Is there somewhere I should look? I have a hall sensor, looking at 5 teeth per rotation, the sensor is wired, I’m mostly just not sure what to do with the multiplier and divider options on the digital input. I have it setup as frequency, and have chosen my adu input. I’m just at a loss regarding the multiplier and divider.

The tire it is watching is a 145/65r15.

I have an EMU Pro 8 connected to the ADU. Do I need to do any setup in there as well to grab the data?

Also, is there a way to get the ECU/ADU to calculate gear based on rpm and speed?

Thanks for any help you can give this ECUMaster newb!

2

If you have free digital inputs in EMU PRO, it is easier to connect the sensor directly to the PRO and then send the speed via CAN to the ADU using the EMU Black CAN stream.

In EMU PRO you only need to select the source and set the ratio in km/h per Hz.

3

Thank you for your response. I do have the free inputs, however, the ECU wiring is kind of stuck where it’s at for now. I converted from another ECU, so everything is semi limited to what was there before, and there wasn’t much. Also, being rear engined, the ECU is in the rear, and the dash is in the front nice and close to the front wheel I’m trying to get data from. I plan to rewire from scratch, eventually. But there will be some major drivetrain reconfiguring that will come with that change.

As of about 10 hours ago, using the base settings for wheel speed on the ADU, I got a reading when spinning the airborne wheel with my foot. I haven’t driven the car yet, as I’m still trying to sort out a few other input issues, but hope to tomorrow, probably. A brief explanation of the multiplier and divider would be very helpful. AI has tried hard, and using info it gave me I got now reading at all at foot spin speed. So I feel like I’m closer now with 1 in both boxes than I was with “calculated” values.

Also, on the pro, regarding gear ratios, I can’t see what it says on the side menu that describes the calculation. Am I supposed to put the mph at a certain rpm for each gear?

4

The Divider and Multiplier options are very self-explanatory.
A digital input with type Frequency measures the frequency of the input signal.

  • If you set the divider and multiplier to 1, then your output value will simply be the frequency of the signal.

  • If you set the multiplier to 10, then the output value will be 10 × input frequency.

  • The same applies to the divider.

Example with your wheel size (145/65R15):

To calculate speed from pulses, you need to know the wheel circumference.

  • Profile = 0,65 × 145 mm = 94,25 mm

  • Diameter = 2 × 94,25 mm + (15 × 25,4 mm) = 188,5 mm + 381 mm = 569,5 mm = 0,5695 m

  • Circumference = π × diameter = 3,1416 × 0,5695 = 1,788 m

So the wheel circumference is about 1,788 m.

If you have 5 pulses per revolution, then:

Speed [m/s] = (Hz × circumference) / pulses

Speed [km/h] = (Hz × circumference × 3,6) / pulses

Example calculation:
If the sensor reads 100 Hz:

(100 × 1,788 × 3,6) / 5
= (100 × 6,4368) / 5
= 643,68 / 5
= 128,736 km/h

So, using multiplier and divider, you can configure the ADU to output speed directly:

Formula:

(Freq × circumference × 3,6) / divider = speed [km/h]

Here, circumference × 3,6 is the multiplier.

  • 1,788 × 3,6 = 6,4368 → multiply by 10000 to make it an integer.

  • Multiplier = 64368

  • Divider = 50000

With this setup:

  • If the sensor gives 100 Hz, then PMU will show 128 km/h.

To add the unit, you need to use a Number element.
If you want 1 decimal place, then the divider should be 5000, and so on.

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5

Haha! You and I have very different ideas of self-explanatory! I don’t have and engineering or coding background, I just machine parts for a living, and turn wrenches and hook up wires for fun.

I appreciate the detailed response. I’m confident I can turn that data into something useful!

Do you have a response to my question about gear ratio on the pro? My screen cuts off the last bit when looking at the place where you input the speed data. I can’t read what I’m supposed to input. Even changing that particular page into a full page on my screen still cuts the right column down to small to hold all of the text.

6

Could you paste a screenshot?

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If you click on the Value and press the Insert button, then this value will go to the graph log where you can check the unit.
We are aware of the issue with longer units being cut, and it will be fixed in the future. Until that time, you can use the workaround I showed.

7

Okay perfect! Thanks for the tip. That’s what I was thinking the value was, 1000rpm.

8

I have edited my previous post, please check it.

9

Bringing this one back up. I got the direct adu speed input working last year, all was well. Now I’ve completely reconfigured the car and am trying to set this up properly using digital inputs at the ECU. I’m getting speed readings on the graph log of the ECU. I’ve got a sensor on a driven wheel and a non driven wheel. Both are showing data, however, the adu sits at 0 but very briefly flashes a number every couple of seconds. It isn’t there long enough to really tell what it’s saying, other than it’s not 0. I have the ADU looking at the ECU.speed data stream. I’ve got lots of other ECU to adu data streams working just fine. It’s just speed that seems to not work yet. I don’t have a data log from the adu, but could probably get one. I’ll attach a project file later today. Thanks for any assistance.

10

Here is an ADU graph log from a drive from just a minute ago, along with the relevant emupro project and adu project.

9-19-26 big changes.emupro (31.5 KB)

Bug Dash New Steering Wheel.adu (10.8 KB)

20260920_1823.adulog (485.1 KB)

11

A log from the EMU PRO would also be useful, since we do not know the speed measured by the EMU PRO.

12

@mfudala_ECUMASTER This is from the same drive as the ADU log above.

2026_0921_0649.emuprolog (1.3 MB)

13

To simplify, I’ve all but removed the relevance of the driven wheel, it’s signal isn’t particularly clean, so now I have the ECU just reporting the non driven wheel. The signal there is much cleaner and very close to reality. But still, I’m not getting a clean output over the ecu.speed channel. What am I missing?

14

At first glance, I cannot find why only the speed is wrong. We checked that EMU PRO is sending the speed correctly on the bench. The rest of the data in this CAN frame seems to be OK in your ADU log

Could you record the CAN stream during the ride using LightClient?
In the “All frames” window, you should see almost every frame from your CAN1.

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Press “Clear trace” (1) once you start the ride, and “Save trace” (2) once you finish.

Could you also provide logs from ADU and EMU PRO that will be collected during the same ride as the raw CAN stream data above?

15

Logs.zip (1.8 MB)

Hopefully this is what you need. Unfortunately, I’m going to guess that the logs are mutually exclusive, since the whatever program I’m viewing has to take control of the USB to CAN. Hopefully you can work with what I’ve provided.

9-23-26.emupro (33.0 KB)

Thanks for your help!

16

As I’ve been putting miles on the car, watching the glitchy speedometer, I’ve noticed that when it glitches away from 0 for and instant every couple seconds, one of the numbers I see is exactly half of what the ECU is reporting on my laptop. Sometimes it’s a fraction of that value, but the half number I see come up consistently enough to not be some random coincidence. Some relevant data does seem to be getting through. It just seems to be corrupted for some reason.

17

@mfudala_ECUMASTER any more thoughts on this? I’ve tried everything I can think of at this point. I’ve got a clean signal into the ECU, but don’t seem to get anything useable out of it. Is there any progress on the development of the EMU Pro can stream rather than the limited EMU Black stream we have had to use for the last few years?

Would there be any benefit to trying to pull the speed data directly out of the CAN stream with some custom script stuff? Would that be easier to setup? Sorry to be a bother here, but I’m really ready for this thing to work as expected.

18

Go to the configuration tab at the top.
Change the source for the ecu.speed channel to the CAN bus.

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19

Thank you for the reply. Will that make this work? Or is that step 1 of pulling that signal out of the ECU? I think I tried switching all of the ECU.speed input options to canbus recently, but found that I then lose the odometer function since it only had ECU.speed and gps.speed as it’s options. At that point I changed back, before any testing, since I didn’t want to lose that function if I didn’t have to.

20

The answer that Marek posts will fix your issue.