Knock module for MS3 (beta test)

[morrische]

I have seen in microcontroler.net a german guy wich is trying to build a Knock Sensor interface with the TPIC8101 and a atmel atmega8 (i think). He made this settings. I don't know if they are right but for him they work (or it seems like they work)

Frequency = 41 (6.94 kHz)
Gain = 63 (0.111)
Integrator = 24 (320us)

Somebody should correct me if i'm wrong (please)? (and i guess i'm wrong for sure like most of the time......... )

[HeinrichG]

I don't think there are enough pins on the MS3 to be able to do that. Certainly the current design doesn't permit that.

James

That's really pity

Regards,
Heinrich

[jsmcortina]

Not having much luck with mine. Seems like there needs to me more attenuation before the signal gets to the ic,

Try adding resistors in series with the circuit (try externally to begin with) 47k or 100k.

James

[elaw]

Not having much luck with mine. Seems like there needs to me more attenuation before the signal gets to the ic, at least with the factory 2JZ knock sensors. With the gain set to 1 the knock gauge always reads 101% with the gain at minimum the knock gauge bounces between 50% and 70% at idle and reads 101% off idle. Haven't had much time this week to tinker beyond installing the module and running it as-is.

Do you know if your engine has a resonant knock sensor? From what I've read, the resonant sensors have a much higher output (like 10x higher) than the non-resonant ones.

Just for comparison, my engine with two nonresonant sensors reads 8-20% at idle and cruise, getting up to 75+% at high RPM full-throttle (gain set to 1).

[elaw]

James,

Just a few notes and questions...

First, in general the board seems to be working well on my 5-cylinder Audi engine with two sensors. Obviously some tuning is going to be required, but I datalogged my drive in to work this AM and behavior was about as I expected. I'll attach my msq and the log in case anyone's interested.

In the "knock sensor settings" window, can you confirm or deny my guess as to how "retard check time" and the coarse and fine steps work? My guess is the 1st time knock is detected, it retards by the coarse step. If knock is detected again within the "check time" it retards again by the coarse step, otherwise by the fine step. Am I right?

Also a minor issue: although I've got the advance check time and step size both set to 0.5, it seems to advance in 1-degree increments at 1-second intervals.

And lastly a request: any chance of being able to log knock value per-cylinder?

A note to anyone looking at the log: I was tuning the system as I went and ended up decreasing the sensitivity a lot. That's why more "knock" is detected at the beginning than the end. Also I removed a lot of chunks in the middle of the log to reduce its size.

Edit: one more thing I forgot to mention: if you look at the very beginning of the log, there's one point where the knock value spikes to 101.3%! I'm not sure it matters but I thought I'd point it out.

[Matt Cramer]

I don't think there are enough pins on the MS3 to be able to do that. Certainly the current design doesn't permit that.

James

That's really pity

Regards,
Heinrich

It looks like you could do V12 / wasted spark with it with the right mods, though.

[jsmcortina]

First, in general the board seems to be working well on my 5-cylinder Audi engine with two sensors.

Good

In the "knock sensor settings" window, can you confirm or deny my guess as to how "retard check time" and the coarse and fine steps work? My guess is the 1st time knock is detected, it retards by the coarse step. If knock is detected again within the "check time" it retards again by the coarse step, otherwise by the fine step. Am I right?

Also a minor issue: although I've got the advance check time and step size both set to 0.5, it seems to advance in 1-degree increments at 1-second intervals

Most of that code is the standard MS2/BG knock code although I made one small change to add an new setting instead of sharing two settings. I need to write up a manual page. The info in the megamanual.com page isn't a totally accurate description of the MS2/BG code, but gives a starting point.

And lastly a request: any chance of being able to log knock value per-cylinder?

These are already in there as sensors9-16

James

[gross polluter]

Do you know if your engine has a resonant knock sensor? From what I've read, the resonant sensors have a much higher output (like 10x higher) than the non-resonant ones.

It does. All of the audio samples I've taken of resonant VS non-resonant sensors seem to suggest the same thing.

[savagerocco]

Hurry up and get these tested......This is something I have been waiting for for far too long......

[mega_user]

As said wasted spark firing two coils at once and sequential fuel is supported for 12 cylinders.

I don't think there are enough pins on the MS3 to be able to do that. Certainly the current design doesn't permit that.

James

That's really pity

Regards,
Heinrich

[Yetidragon]

I am just about to megasquirt3 my MX5 (picking the kit up from the post office tomorrow) and i am very interested in adding this to my setup.
Definately want to be in the next batch please

[Metaworld]

Not having much luck with mine. Seems like there needs to me more attenuation before the signal gets to the ic, at least with the factory 2JZ knock sensors. With the gain set to 1 the knock gauge always reads 101% with the gain at minimum the knock gauge bounces between 50% and 70% at idle and reads 101% off idle. Haven't had much time this week to tinker beyond installing the module and running it as-is.

Any advice on setting integrator time constant? Can't really figure that one out.

Set your Gain Higehr. Gain is the Level of the Knock Sensor Voltage. The Integrator Time is the Time which the TPIC Sampels Knock Signals. If the the Int/Hold Signal comes to the Tpic it starts to count. So you longer set your Integrator much more Noise you get.

Maybe James Could Tell me the something about his Pinout for the TPIC to MS

Pin 7 Int/Hold ->MS
PIN 8 CS -MS
Resonator Frequenz on Pin 9+10
Pin 11 SDO (MISO)
PIn 12 SDR (MOSI)
Pin 13 SCLK (SCK)

Where is the Test Pin wired?
Here is the Layout which is Designd from a friend of mine Peter Diener. We use this for external solution an listing to the Knock Sensor.

http://www.mikrocontroller.net/wikifile ... or_sch.pdf

Kind Regards

[jsmcortina]

I don't have the schematic to hand, but I'm pretty sure that 'Test' is NC.

James

[Metaworld]

Did you use the Adavanced SPI Mode to get the Knock Level? Maybe it would be possible that you could send me an pinout to connect my TPIC to MS3 or an schematic.

Kind Regards Stefan.

[tpsretard2]

hi James, got her back up and running, i also got the knock board installed..

at idle with my noisy engine it will flutter between 10-20, and driving it will be 40-50.
will get all the settings, but from the time the engine is started, the knock indicator comes on, no matter what settings i use it will not go off.

?? Is this normal behavior.

[elaw]

Can you post your msq file?

[tpsretard2]

here it is..

[elaw]

Well your settings look pretty good, although if knock is running 40-50 when driving (and the engine is not knocking), you might want to raise the thresholds a bit - I'd try increasing them by 10 or even 20 percent at all RPMs.

Also I wonder if this could be a quirk related to the fact that your maximum retard is set to 0? Have you tried setting it to a > 0 number?

One thing I've noticed on my setup is that I get a single very high spike in the knock number at startup - if yours is doing the same thing that might explain why it's showing knock from the moment the engine starts.

If you continue to have trouble, you probably should take a data log and post it too - that might help identify the problem.

[tpsretard2]

yea i tried more than 0,

but now you have me thinking, i can swing as much as 60 when cranking..
The clearances are VERY VERY loose on this engine, so it is very noisy, even with the 60wt oil.

Could this be some area that can be worked on then, the indicator i would not of though you would want staying on at all. maybe a delayed turn off, but not a stay on all the time.

also the knock counts, i am amusing this how many time is crosses the set threshold right ??

[jsmcortina]

Could this be some area that can be worked on then, the indicator i would not of though you would want staying on at all. maybe a delayed turn off, but not a stay on all the time.

The current ini just turns the light on if "knock" is non-zero.

also the knock counts, i am amusing this how many time is crosses the set threshold right ??

Yes.

James