[Diy_efi] Continuing the chip switcher "problem"

Tue Feb 15 06:20:12 GMT 2005

Ok everybody,
     I've been doing more homework.  The processor that is driving this
whole thing is a OKI M66207.  I found datasheets on it.  Would the
signal I'm trying to find that connects to the not OE line of my
eeprom be a direct output of the MCU?  I'm trying to trace where this
line goes so I can confirm whether there is a problem with the signal
or not.  Perhaps a bad solder or something.

Marcello


> Marcello,
>
> This chip the 74HC373 is a 'transparent latch'. The Q ouputs follow the D
> inputs.
> This is used for demultiplexing the bus Address's from the data.
> Mostlikely
> its a 8 bitter in the ECU.
>
> It typically does not drive the chip selects.
> Although it may be used as  a buffer in transparent mode.
>
> If you do latch the upper 2 bits use a true latch.
>
> Cheers
>
> ----- Original Message -----
> From: <mbelloli at speedymotorsports.com>
> To: "A list for Do-It-Yourself EFI" <diy_efi at diy-efi.org>
> Sent: Monday, February 14, 2005 5:15 PM
> Subject: RE: [Diy_efi] Continuing the chip switcher "problem"
>
>
>> Everyone,
>>      I got a chance to play a bit this afternoon.  Maybe this piece of
>> information will help.  When an eprom is installed in the ecu, you
>> have to install a 74hc373 along with it.  These were both already in
>> the ecu I am working with so didn't think that much about it.  Here
>> is a link to a datasheet on that 3-state latch.
>>
>> http://www.jameco.com/wcsstore/Jameco/Products/ProdDS/45831.pdf
>>
>> Would this chip be supplying the signal to the not OE line? or the not
>> CE
>> line?  I'm going to take the ecu home tonight and do some probing.  I'm
>> just thinking maybe this is the latch I need, and won't need anything
>> else.
>>
>> Thanks,
>>
>> Marcello
>>
>>
>>
>>
>>
>> > Have you thought of using several chips the same size as the stock
>> prom
> in
>> > parallel, and using flip-flops/logic to toggle the OE and CE lines to
>> > enable
>> > which chip you want?  That was another way I did it on my Buick GN
> before
>> > I
>> > went to a single larger chip... The problem may lie in the fact that
>> the
>> > code is in the chip as well as the tables... GM was only tables...
> Another
>> > option is see if you cant build a small circuit to multiples one chip
> with
>> > the code and a flash for the tables and only change the tables...
>> >
>> >
>> >> -----Original Message-----
>> >> From: diy_efi-bounces at diy-efi.org
>> >> [mailto:diy_efi-bounces at diy-efi.org] On Behalf Of
>> >> mbelloli at speedymotorsports.com
>> >> Sent: Monday, February 14, 2005 10:49 AM
>> >> To: A list for Do-It-Yourself EFI
>> >> Subject: Re: [Diy_efi] Continuing the chip switcher "problem"
>> >>
>> >> Will,
>> >>      Unforunately the image is everything in one.  Both code
>> >> and tables.
>> >> I have put a link to the 29c010 on my webpage as well.
>> >>        http://home.comcast.net/~hexibot43/ChipEnableLogic.htm
>> >>
>> >>      I had gone to the Pic Chip because I had a lot of other
>> >> ideas I'd like to add as time goes by.  I wanted to be able
>> >> to change to the code on the fly in one bank while running on
>> >> another bank.  I could then switch it in after the changes
>> >> and the checksum were calculated.
>> >>  And I wanted to have a nice display because none of my
>> >> friends understands what I am doing, but they understand
>> >> plain english when it is in front of them.  I thought to
>> >> maybe use a graphic display later, which would allow me to
>> >> incorporate displaying the tables for fuel and spark.  I also
>> >> want to later add datalogging capability.
>> >>      I am thinking could I use this latch with my pic?  I
>> >> would supply the new hi order address I would like to it, and
>> >> when the time is right the latch would do the actual switch
>> >> for me?  That way take the problem of the switching
>> >> completely away from my pic.
>> >>      I have another working computer that I have not modified
>> >> at the shop.
>> >>  I am going to go put my DSO on the Not OE line and see what I get.
>> >>
>> >> Thanks to everyone,
>> >>
>> >> Marcello
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> > Marcello,
>> >> >
>> >> > A further thought on this - can we assume that what you have in the
>> >> > 29C010 is the fuel / ignition map ONLY, i.e. no executable
>> >> code?  If
>> >> > it contains both, then more complexity is needed, because you only
>> >> > want to  assert the altered higher address lines when a fuel /
>> >> > ignition lookup is being  performed.
>> >> > But
>> >> > you could still use the simple approach Bevan & I are
>> >> advocating if
>> >> > you have four images of the executable code as well, each
>> >> with  their
>> >> > own respective map but otherwise identical.
>> >> >
>> >> > Regards
>> >> >
>> >> > Will Cowell
>> >> > _______________________________________________
>> >> > diy_efi mailing list
>> >> > diy_efi at diy-efi.org
>> >> > http://lists.diy-efi.org/mailman/listinfo/diy_efi
>> >> >
>> >>
>> >> _______________________________________________
>> >> diy_efi mailing list
>> >> diy_efi at diy-efi.org
>> >> http://lists.diy-efi.org/mailman/listinfo/diy_efi
>> >>
>> >
>> > _______________________________________________
>> > diy_efi mailing list
>> > diy_efi at diy-efi.org
>> > http://lists.diy-efi.org/mailman/listinfo/diy_efi
>> >
>>
>> _______________________________________________
>> diy_efi mailing list
>> diy_efi at diy-efi.org
>> http://lists.diy-efi.org/mailman/listinfo/diy_efi
>>
>
>
> _______________________________________________
> diy_efi mailing list
> diy_efi at diy-efi.org
> http://lists.diy-efi.org/mailman/listinfo/diy_efi
>

_______________________________________________
diy_efi mailing list
diy_efi at diy-efi.org
http://lists.diy-efi.org/mailman/listinfo/diy_efi