EST observations (kinda long)

[Bruce Plecan]

-----Original Message-----
From: Ludis Langens <ludis at cruzers.com>
To: gmecm at efi332.eng.ohio-state.edu <gmecm at efi332.eng.ohio-state.edu>
Date: Tuesday, February 23, 1999 1:04 PM
Subject: Re: EST observations (kinda long)

Distributor..
Is there something in what you just printed that would invert the EST line,
by changing it?
Er, is this just the dwell end of things, or did I just miss the point?..
Bruce


>Tedscj at aol.com wrote:
>>
>> You see that these are all equally spaced.  The P4 document states that
the
>> ECM looks for the 'falling edge' to determine a reference pulse.  I have
read
>> and heard that the difference between an HEI module and DIS module is
that
>> this signal is inverted.  So maybe a DIS .bin looks for a 'rising edge'?
>> Either way it can't be much of a problem since even an inverted signal
has a
>> 'falling edge'.  You might just have to adjust the base timing to make up
for
>> the pulse displacement caused by the inversion.
>
>The problem is that the other edge may "move around" at different RPMs.
>
>
>Here is the dwell computation code from the SyTy (and turbo Sunbird)
>program.  All the named locations are RAM variables except for
>TachInterval which comes from the hardware timing chip.  Notice that all
>of the constants are hard coded, none are read from the configuration
>area.  (Question:  Are the SyTy and Sunbird distributor or DIS?)
>
>This code fragment is invoked at 80 Hz
>
>xD035   ...
>        LDX     TachInterval    ;Hardware register
>        LDAA    #255            ;Dummy huge ExtraDwell
>        LDAB    Flags2F
>        BITB    #bigMapIncrease
>        BNE     @0              ;Force ExtraDwell := (TachInterval / 8)
>        LDD     OldTachInterval ;OldTachInterval - TachInterval
>        PSHX
>        TSX
>        SUBD    (X)
>        PULX
>        ASLD                    ;Double difference
>        SUBD    ExtraDwell      ;Extra dwell if RPM increased
>        BMI     @1
>        ADDD    ExtraDwell
>@0      STD     ExtraDwell
>
>@1      PSHX                    ;TachInterval to D
>        PULD
>        LSRD                    ;TachInterval / 8
>        LSRD
>        LSRD
>        SUBD    ExtraDwell      ;Limit ExtraDwell to (TachInterval / 8)
>        BHS     @2
>        ADDD    ExtraDwell
>        STD     ExtraDwell
>
>@2      PSHX                    ;TachInterval to D
>        PULD
>        STD     OldTachInterval ;Set new OldTachInterval
>        LSRD                    ;Compute Dwell using TachInterval
>        SUBD    #229
>        BHS     @3
>        ADDD    #308
>        BRA     @5
>@3      LSRD
>        SUBD    #295
>        BLO     @4
>        ADDD    #382
>        BRA     @5
>@4      ADDD    #1527
>        LSRD
>        LSRD
>@5      STD     Dwell
>
>        LDAA    #120            ;Increase dwell at low volts
>        DIFA    SensedVolts
>        LDAB    #4
>        MUL
>        ADDD    Dwell           ;Combine all terms
>        ADDD    ExtraDwell
>        STD     Dwell
>
>        LDD     TachInterval    ;TachInterval - 39
>        SUBD    #39
>        SUBD    Dwell           ;Limit Dwell to (TachInterval - 39)
>        BHS     @6
>        ADDD    Dwell
>        STD     Dwell
>@6      ...
>
>This code fragment slowly reduces ExtraDwell to zero.  It is executed
>once per ignition event (up to 80 Hz).
>
>xCE2F   ...
>        LDD     ExtraDwell      ;ExtraDwell / 8
>        LSRD
>        LSRD
>        LSRD
>        COMA                    ;- (ExtraDwell / 8) - 1
>        COMB
>        ADDD    ExtraDwell      ;ExtraDwell - (ExtraDwell / 8) - 1
>        BPL     @9
>        CLRD
>@9      STD     ExtraDwell      ;Decay ExtraDwell to zero
>
>--
>Ludis Langens                               ludis (at) cruzers (dot) com
>Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/
>