crankshaft/flywheel encoder patterns

[Mark Eidson]

At 10:56 AM 12/3/96 -0800, you wrote:
>Mark Eidson wrote:
>> 
>> This is the same approach I have come up with but I'm only in the thought
>> process.  Are you going to sequence your counters so that each cylinder will
>> have a programmable injection timing?  This will also work for ignition.  I
>> thought a phase locked loop running at a higher frequency would give more
>> accuracy than 1 degree of cam rotation but can't figure out an easy to get
>> the dynamic range required.  me
>> ***************************************************************************
>> * Mark Eidson                        Voice: (602)752-6513                 *
>> * Staff Design Engineer                Fax: (602)752-6000              
>
>Hi Mark,
>
>Yes, I plan to sequence them, and I'm using the same approach for 
>ignition coils.  Also, with one edge per crank degree, we can narrow our 
>resolution to 0.5 degrees of cam rotation not 1 degree, and for my 
>purposes this is accurate.  I know there are systems out there that claim 
>they are more accurate, but I don't know beyound 1/2 degree if it makes a 
>difference.
>
>The reason I decided to go this route was to relieve the processor from 
>too many interrupts.  I plan to set the processor up to be interrupted on 
>every rising edge of the crank sensor (once every 2 degrees of crank 
>rot).  When there is a rising edge on the CAM, I'll set angle to zero, 
>and increment by two on every crank interrupt.  I then reload the 
>counters (by writing to a memory location), when their proper angle comes 
>up.
>
>I'd like to discuss this more, but I'm out of time right now.  Write me 
>back on what you think.
>
>
Have you thought of using the flywheel or flex plate teeth for the source of
timing pulses?   This would give more resoultion if accurate pickup can be
made.  I was thinking of using a single counter and decoders for each
injector and spark plug.  The cam pulse resets the counter and each set of
decoders would be loaded with the start and stop count.   This may take more
hardware but allows for positioning and duration control.  Once loaded the
system requires no CPU action under steady state conditions.  me
***************************************************************************
* Mark Eidson                        Voice: (602)752-6513                 *
* Staff Design Engineer                Fax: (602)752-6000                 *
* Manager System Integration and                                          *
*   Verification                    E-Mail:  mark.eidson at tempe.vlsi.com   *
* VLSI Technology, Inc.                                                   *
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