[joey120373]

VR sensor polarity backwards.

That's what the tooth log indicates.

the first time I connected this, weeks ago, i had the vr polarity swapped, if you look at the first scope pics with my handheld scope, you will notice that after the missing tooth, the voltage swings negative. I assumed this was incorrect as the max 9926 is set to zero crossing. So i swapped the VR leads ( the board has jumpers for this as the wiring diagram doesn't say what wire is what, and niether lead is grounded at the stock ECU ). As far as I have been able to test, swapping the polarity didn't help or harm anything, it still will not read rpm with the trigger wheel setting at 36-2. and seems to be fine, at least with a running engine, with the 36-2-2-2 setting. I can swap it back easy enough though. my main question then is,
what should the trigger logger look like when its all configured correctly?

Thank you for the help .

[theonewithin]

1 single high bar and the rest short.

And as its a 36-2 that tall bar should be 3 times the height of the others.

Make sure you are also using the correct edge detections for your conditioner.

[joey120373]

1 single high bar and the rest short.

And as its a 36-2 that tall bar should be 3 times the height of the others.

Make sure you are also using the correct edge detections for your conditioner

Ok, well it pretty much is, after I posted that question I did a search on the trigger logger, and the first example I found was a 36-2 wheel and it looked very similar to what I see. I did not get a pic of the logger at higher RPMs, but the gap, or the highest bar, stays roughly the same height, the rest of the teeth, except tooth 1, all settle down and are exactly the same length, but tooth 1 ( first pulse after the gap ) is consistently taller than the rest. By about 10-15% I would guess.

So with the rpm stable, the logger looks very similar to this . I will play with it some more to see if I can get the 3 times longer gap bar, and see if that works. But I am wondering if that longer tooth “1” could also be causing a problem.

Thanks again

[PSIG]

Most (not all) problems with VR are not properly combining the two basic requirements, which are correct polarity and the matching correct trigger edge setting for the conditioner type used. IMO you're having two issues. First, the 'scope image above indicates correct polarity, but as you're using a MAX9926 (inverting), the Trigger Edge should be RISING. See where that gets you first, and post a 'scope image.

There are exceptions to every rule but… "Correct polarity" means the sensor voltage rises on an approaching tooth edge, and swings the voltage negative on a departing tooth edge. This is a requirement in order for the sensor to properly detect the gap. To help get your brain wrapped around it, look at the 'scope trace and only "see" either rising, or falling edge crossings. That is what Speeduino will also "see". The correct choice will visually replicate one set the edges of the target wheel. For a missing-tooth wheel, that will be the physical falling tooth edges, and a correct polarity will show negative voltage on those edges, and the conditioner will either pass those (Falling) or invert those (Rising).

For a quick reference to polarity (concept only), see here: http://mcs.woodward.com/content/motohaw ... acing.html
For an example of how to combine polarity and conditioning: viewtopic.php?f=13&t=2456&p=30961#p30961

Next possible problem is that most users have the MAX in an A-mode ("smart" adaptive). Because your wheel and sensor produce a large pulse on the first tooth after the gap, it may adapt to then miss the next tooth. We should be able to see if this is also an issue with your next post. The common fixes for this issue are to run the MAX in a non-adaptive mode (B), or use a different non-adaptive signal conditioner, or use a different type of sensor.

David

[joey120373]

PSIG,
Thank you, I was pretty sure I had the VR sensor correct this time around, with the voltge rising as the next tooth approached.
I was also worried about the adaptive peak threshold mode when I saw the trigger logger at idle. That’s why I put the VR signal next to the 9926 output on the scope, to see if it was missing a tooth. It doesn’t appear to be. However it’s entirely possible that it is messing up the works while the engine is cranking.

Looking at my schem, I indeed have it operating in A2 mode, so to fix that I just need to pull pin 13 off ground and tie it to VCC. Should have thought of that while designing the board . That’s why we have to test these things. I also have one of your sensor input board I could wire in there as well. I did make small test points for the VR because I thought I might have to play with it a bit. It will be a couple weeks before I get a chance to mess wit it again, but I can modify the board while I am at work.

Thanks for your help, like I said, I was concerned about the irregular engine speed messing with the 9926, buy it didn’t sink in till you mentioned it.

I’ll let you know what I find, and I will have some real scope screen shots next round of testing.

[joey120373]

Just ordered another dual signal conditioner board to test with. Thanks

[joey120373]

Oh, and just to be clear, the vast majority of testing I was doing I had the trigger edge set to “RISING” , the .msq I posted was evidently saved right before I quit, and I was playing with the trigger wheel options and the edge event, and had left it on “FALLING” .
I was only swapping between 36-2, rising and falling and
36-2-2-2 both rising and falling, so not really a whole lot of combinations to try.