[Diy_efi] Another Eprom Question

Wed Jan 26 06:27:54 GMT 2005

Bevan,
     I have created separte checksums for each bank, or bin.  So when I
switch to a different bank, I also am switching to the checksum that
goes with that bin.  You know, I have no idea if the computer runs a
checksum more than once durning a key on cycle.  I would think that
it is only done on original startup, but perhaps I'm wrong.  I never
created a checksum of all the images together.  I basically pieces a
large file together out of bins that I had created previously.  You
are right in that when I finally get to making small changes to the
bin/image that I will have to generate a new checksum and save that
along with my other changes.  I'm just trying to get it to work with
images that I won't be changing first.  I have four different
bin/images that I'm switching between for now.

Thanks,
Marcello


>
> I think the problem is quite different than what everyone else has
> suggested.
> I'd guess that you're creating all your images seperately then joining
> them
> together, then placing one checksum on the whole combination.
> Each image needs it's own checksum independent of all the others.  And
> these
> checksums have to be located within their independent memory ranges where
> the ECU will look.  On top of this they have to be correct ofcourse.  So
> if
> you modify the base image, then you will need to regenerate the desired
> checksum for it.
>
>
> Regards,
> Bevan
>
>
> -----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: Wednesday, January 26, 2005 6:32 PM
> To: A list for Do-It-Yourself EFI
> Subject: Re: [Diy_efi] Another Eprom Question
>
> Thanks, I'll give it a look.  I didn't debounce the switches.  I had tried
> using some very different chips the first time around.  But as you
> mentioned
> I now based all my chips on the exact same baseline chip.  I was thinking
> my
> future design was to use 2 banks as you've said as a frame buffer.  Make
> my
> changes to the bank not in use, and then switch banks.
>      Why don't I have to worry about the OE and CE lines?  Just change the
> address lines and I'm all good? I'm going to give it a try.  I'll be using
> a
> pic to do the switching now, so maybe that will take care of the debounce
> issue.  I just figured if it wasn't working with my rotary switch it
> wouldn't work with the pic.  But the rotary switch was not debounced.
> Maybe
> that was the center of my problem.  When I get to work tomorrow I'll have
> a
> new program ready to go, and give it a try.
> Thanks,
> Marcello
>
>
>
>> Hi guys
>>
>> this topic came up many years ago on this list .....im not sure how
>> far back the archives go but i did explain in depth back then.  Its
>> been a while since i did a bank of 4 .....done many 2 way but the
>> major problems were:
>>
>> all 4 eprom images need to be from the same base profile then mods
>> made
>>
>> debound curcit or judt pull down resistors need to be used to stop the
>> ripple effect of the switching
>>
>> make sure you have a good +5 volt into the new chip.
>>
>> you should not need to use the CE for switching at all .....all
>> switching should be done from the top 2 address lines .....dig through
>> the archives ...  I did post drawings for all to use.  If not i will
>> see if i can dig em up.
>>
>> Justin
>>
>>
>>
>> Quoting mbelloli at speedymotorsports.com:
>>
>>>      Ok, I just checked that the access times.  The stock original
>>> chip had no better than a 150ns access time.  My 29C010 has a 70ns
>>> access time.  So I've got that covered.  I'm better than 1/2 the
>>> original access time.
>>>  Mab
>>> > What's the access time on the 29C010?  is it as fast or faster than
>>> the
>>> > original EPROM?  if not that could be the problem.
>>> >
>>> >
>>> > -------Original Message-------
>>> >
>>> > From: mbelloli at speedymotorsports.com
>>> > Date: 01/25/05 20:00:42
>>> > To: A list for Do-It-Yourself EFI
>>> > Subject: Re: [Diy_efi] Another Eprom Question
>>> >
>>> > I sure hope not!  I'm really trying to get this all set up to do
>>> > minut changes on the fly.  I need an eeprom to be able to do that.
>>> > Soon
>>> enough
>>> > here I'll have it so I just am changing a small part of the whole
>>> program
>>> > instead of the whole thing.  I want to be able to make changes to
>>> > the fuel table, and spark table while driving.  Not just switch out
>>> > one chip
>>> for
>>> > another.
>>> > Thanks,
>>> > Marcello
>>> >
>>> >> wonder if part of the problem isn't the 29C010...  I'd try it with
>>> >> a 27C010 and see if you have the same problem...
>>> >>
>>> >> -------Original Message-------
>>> >>
>>> >> From: mbelloli at speedymotorsports.com
>>> >> Date: 01/25/05 18:17:19
>>> >> To: A list for Do-It-Yourself EFI
>>> >> Subject: Re: [Diy_efi] Another Eprom Question
>>> >>
>>> >>      That is basically what I have now, but it is setting the
>>> >> check engine.  And you will have basically a prom error, and the
>>> >> vehicle running off something other than the chip.  It runs like
>>> >> crap.  This is in a 1993 Acura Integra with a GSR motor, and a p28
> computer.
>>> >> Stock came with a 27C256.  It already had an eprom in it.  Now it
>>> >> doesn't do it every time.  I like every third time it will set the
>>> >> check engine lamp.  you'll have to clear codes, or disconnect the
>>> >> battery to get it running correctly again.
>>> >>
>>> >> Thanks,
>>> >>
>>> >> Marcello
>>> >>
>>> >>>  Back in 87 I was running a 27C512 with 4 programs on my Buick
>>> GN...
>>> >>> had a small board the chip was on and a shielded ribbon going to
>>> >>> the ECM.
>>> >>> would toggle the 2 highest address bytes with a thumbwheel on the
>>> dash
>>> >>> to
>>> >>> change banks and did it on the fly all the time with no CE light.
>>> >>>
>>> >>>
>>> >>> -------Original Message-------
>>> >>>
>>> >>> From: mbelloli at speedymotorsports.com
>>> >>> Date: 01/25/05 15:13:07
>>> >>> To: diy_efi at diy-efi.org
>>> >>> Subject: [Diy_efi] Another Eprom Question
>>> >>>
>>> >>> Hello everyone,
>>> >>> I have been pulling my hair out trying to figure out another one
>>> >>> of these chipping ideas. I am trying to set up a controller to
>>> >>> allow the switching of which chip the ecm of a car computer is
>>> >>> running on the fly while driving. Currently I've got it working
>>> >>> very well if you switch with the key off, but not while running.
>>> >>> The original chip was a 27C256, which switched out for an ATMEL
>>> >>> AT29C010. I really only wanted 4 choices, which this chip more
>>> >>> than allows. I am trying to set it up so I can have pic processor
>>> >>> do the switching for me. I cound't put a picture of the waveform
>>> >>> that is driving me crazy here so I put it on my website at
>>> >>>
>>> >>> https://home.comcast.net/~hexibot43/ChipEnableLogic.htm
>>> >>>
>>> >>> I just can't understand why it is working right now with the
>>> >>> signal
>>> I
>>> >>> have
>>> >>> on the Output enable pin. From what I understand it shouldn't be
>>> >>> working, but it is working. I thought I was going to simply look
>>> >>> at the
>>> signal,
>>> >>> and see drops to ground like I did with the last car computer I
>>> looked
>>> >>> at.
>>> >>> I figured I could use that as a trigger for an interrupt the
>>> >>> would
>>> in
>>> >>> turn wait a set amount of time and then switch banks. This way I
>>> could
>>> >>> do
>>> >>> the switching when the chip was not be read from, and so the ecm
>>> would
>>> >>> be
>>> >>> happy and not throw an check engine lamp at me.
>>> >>> Can anybody sheld some light on this for me? You guys did so well
>>> >>> helping me last time, I hope you can do it again. And yes, I
>>> >>> still have a lot more to learn.
>>> >>>
>>> >>> Thanks,
>>> >>>
>>> >>> Marcello
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