[Diy_efi] Re: diy_efi Digest, Vol 17, Issue 11

Mon Feb 14 05:03:33 GMT 2005

Bill,
     I think you might be the man with answer.  I'm ok with the software
end of this project.  It has been the hardware that has been my
stumbling block.  I just don't have experience at looking at the
logic states of all the pins on this chip.  My chip is working and
running in the computer right now.  It only has a problem when I do a
switch.  What do you think of the signal on my Output Enable line?
      http://home.comcast.net/~hexibot43/Waveforms.htm

These waveforms were taken with the computer active, but the car not
running so there could be no interference from ignition.

Marcello

> Marcello,
>     I would agree that switching in the middle of a read is likely to be
> the cause of the check engine light - When the switch over happens in
> the middle of a read you are probably going to get at least one 'bad
> read' - ie rubbish byte, and this could be anywhere in the program.......
>     If you use the pic to do the switchover you should be able to
> control when it occurs - ie have it complete all processes/interrupts
> etc, suspend servicing any new ones, jump to a  switchover routine which
> can then achieve a clean switchover, then return to normal operation.
>
>     I am a hardware engineer, not a software guru, so the description
> may be a bit simplistic, but I believe this approach should yield a
> viable solution.
>
> Regards
> Bill
>
>>
>>Message: 1
>>Date: Thu, 10 Feb 2005 18:46:31 -0500 (EST)
>>From: mbelloli at speedymotorsports.com
>>Subject: [Diy_efi] Continuing the chip switcher problem
>>To: diy_efi at diy-efi.org
>>Message-ID:
>>	<4860.67.121.93.112.1108079191.squirrel at www.speedymotorsports.com>
>>Content-Type: text/plain;charset=iso-8859-1
>>
>>Hello Everyone,
>>     I had asked the question eariler in regards to creating a mulitple
>>bank chip switcher for an ecm.  Everyone basically said I should be
>>able to just switch the chip without any regard for whether the chip
>>is being accessed during the switch.  I finally got my pic chip
>>controller up and running.  I'm running at 20mhz, and when I do a
>>switch I'm still getting a check engine light.  2 out of three times.
>> Thinking about this, I put the same exact bin in each of the banks
>>of the chip, and still get the same response.  Could it not be that
>>I'm switching in the middle of a read, and that is causing this
>>problem???  What does everyone think.  If I turn the car off, and do
>>the switch no problem.  I'm using this on a 1991 acura integra....had
>>a 27c256 as the base chip, and I'm using a 29c010 as the replacement.
>> I'm controlling the highest two address lines as bank select for a
>>total of 4 banks.
>>     I'll put the info for chip changer on my webesite, and add a link to
>>it tonight.
>>
>>     Any ideas???
>>
>>Thanks,
>>
>>Marcello
>>
>>
>>------------------------------
>>
>>Message: 2
>>Date: Thu, 10 Feb 2005 18:57:41 -0500
>>From: David Cooley <n5xmt at bellsouth.net>
>>Subject: Re: [Diy_efi] Continuing the chip switcher problem
>>To: A list for Do-It-Yourself EFI <diy_efi at diy-efi.org>
>>Message-ID: <1108079861.4995.6.camel at n5xmt.bellsouth.net>
>>Content-Type: text/plain
>>
>>I think it all depends on how the ECM is accessing the chip...
>>I know this wasn't a problem on GM's at least thru 95...
>>
>>
>>On Thu, 2005-02-10 at 18:46 -0500, mbelloli at speedymotorsports.com wrote:
>>
>>
>>>Hello Everyone,
>>>     I had asked the question eariler in regards to creating a mulitple
>>>bank chip switcher for an ecm.  Everyone basically said I should be
>>>able to just switch the chip without any regard for whether the chip
>>>is being accessed during the switch.  I finally got my pic chip
>>>controller up and running.  I'm running at 20mhz, and when I do a
>>>switch I'm still getting a check engine light.  2 out of three times.
>>> Thinking about this, I put the same exact bin in each of the banks
>>>of the chip, and still get the same response.  Could it not be that
>>>I'm switching in the middle of a read, and that is causing this
>>>problem???  What does everyone think.  If I turn the car off, and do
>>>the switch no problem.  I'm using this on a 1991 acura integra....had
>>>a 27c256 as the base chip, and I'm using a 29c010 as the replacement.
>>> I'm controlling the highest two address lines as bank select for a
>>>total of 4 banks.
>>>     I'll put the info for chip changer on my webesite, and add a link
>>> to
>>>it tonight.
>>>
>>>     Any ideas???
>>>
>>>Thanks,
>>>
>>>Marcello
>>>
>>>_______________________________________________
>>>diy_efi mailing list
>>>diy_efi at diy-efi.org
>>>http://lists.diy-efi.org/mailman/listinfo/diy_efi
>>>
>>>
>>
>>
>>------------------------------
>>
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>>diy_efi mailing list
>>diy_efi at diy-efi.org
>>http://lists.diy-efi.org/mailman/listinfo/diy_efi
>>
>>
>>End of diy_efi Digest, Vol 17, Issue 11
>>***************************************
>>
>>
>>
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