[Diy_efi] Continuing the chip switcher "problem"

[David Cooley]

That chip is probably between the 8 data lines of the EPROM and the main
data bus of the ECU.
If your chip was inserted direct onto the bus of the ECU, that would explain
the problem.
 

> -----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 5:16 PM
> To: A list for Do-It-Yourself EFI
> 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