Knock Detection with variable sensitivity over RPM

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Staska
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Re: Knock Detection with variable sensitivity over RPM

Post by Staska »

Nice work. Sorry, for not finding it before my post. Have you considered of tach signal as reference for knock window ? It is easier, than adding support for all king of trigger support. I have already scoped it, for ms1 chip it is same as trigger input, for ms2 ~10-20deg before trigger input. Also - did you managet to place knock code outside of main loop ? Or you didn't modified ms software ?

http://www.msextra.com/forums/viewtopic ... 91&t=41686
HOODEY
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Re: Knock Detection with variable sensitivity over RPM

Post by HOODEY »

So can you explain your algorithm using tach? Is the start ofthe knock window consistent? Is the length of the window
consistent? I did not touch the MS. Just provide it with information it needs to know.
Staska
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Re: Knock Detection with variable sensitivity over RPM

Post by Staska »

Hello. Tach out is used for engine phase detection. The begin of knock window - 10 degree ATDC and end 60 degree ATDC is determined inside microcontroller and is configurable using two pots.

I just found tach out having constant phase and easier to implement, than trigger whell support.
HOODEY
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Re: Knock Detection with variable sensitivity over RPM

Post by HOODEY »

So how do you calculate 10atdc. What reference point do you have for doing this? Is the tach out based on spark or cam reference from the ms?
Staska
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Re: Knock Detection with variable sensitivity over RPM

Post by Staska »

It is just experimental. I am using tach out as referenece, 10 and 60 degree is calculated by atmega. But problem is with ms code, it will not work propertly. It is solved in ms3 chip.

http://www.msextra.com/forums/viewtopic ... 0&start=20
HOODEY
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Re: Knock Detection with variable sensitivity over RPM

Post by HOODEY »

You are not answering the question? How do you know you are at 10atdc? :roll: Is the tach signal occurring at a specific angle or is it based on the spark pulses?
Staska
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Re: Knock Detection with variable sensitivity over RPM

Post by Staska »

I calculate it.
HOODEY
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Re: Knock Detection with variable sensitivity over RPM

Post by HOODEY »

?????
Last edited by HOODEY on Sun Nov 13, 2011 9:13 am, edited 1 time in total.
Staska
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Re: Knock Detection with variable sensitivity over RPM

Post by Staska »

HOODEY wrote:How do you calculate a fixed point when rpm is varying and ignition timing is varying?
My assumption is that the tach signal is based on spark pulses i.e (varying ignition timing i.e varying degrees before tdc).
No no and no. Tach out is stable in phase. For ms1 it is same as trigger event, for ms2, 10 degree after, but in both cases it does not depend on spark angle ATTALL.
HOODEY
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Re: Knock Detection with variable sensitivity over RPM

Post by HOODEY »

What trigger event? Are you talking about the cam reference? Your saying that the tach output is the same as the cam reference signal? :?:

For ms1 it is same as trigger event, for ms2, 10 degree after,
jsmcortina
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Re: Knock Detection with variable sensitivity over RPM

Post by jsmcortina »

HOODEY wrote:What trigger event?
The internal trigger event as set in ms2_extra_ign_wheel.c or by the chosen trigger teeth in MS1/Extra.

James
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HOODEY
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Re: Knock Detection with variable sensitivity over RPM

Post by HOODEY »

?????
Last edited by HOODEY on Sun Nov 13, 2011 8:42 am, edited 1 time in total.
jsmcortina
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Re: Knock Detection with variable sensitivity over RPM

Post by jsmcortina »

HOODEY wrote:Okay ..so you basically have a cam reference.
no?

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
New users, please read the "Forum Help Page".
HOODEY
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Re: Knock Detection with variable sensitivity over RPM

Post by HOODEY »

Reflected on this and I think I will keep my desing as is. :RTFM:
HOODEY
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Re: Knock Detection with variable sensitivity over RPM

Post by HOODEY »

HOODEY
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Re: Knock Detection with variable sensitivity over RPM

Post by HOODEY »

bmw5002
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Re: Knock Detection with variable sensitivity over RPM

Post by bmw5002 »

Any news? We need a reliable and affordable knock detection system...
HOODEY
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Re: Knock Detection with variable sensitivity over RPM

Post by HOODEY »

bmw5002
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Re: Knock Detection with variable sensitivity over RPM

Post by bmw5002 »

Hmmm interesting, now is this using the dsp based Texas instruments knock chip?
HOODEY
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Re: Knock Detection with variable sensitivity over RPM

Post by HOODEY »

Correct..
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