[Diy_efi] Re: diy_efi Digest, Vol 17, Issue 15

[Bill Washington]

Marcello,
    Quite frankly, it looks horrible! - That being said however, if it 
was, in reality, that horrible, I believe that it simply would not work, 
since it appears to never reach a logic '0' level - ergo there must be 
something strange about the way it is being captured or where it is 
being captured!
    It has the appearance that when you probe the OE line that the probe 
may be shorting to another track/wire/pin which has a pull up to 5V 
which is about as strong as the pull down of the driving chip  ----  
thus 2V5..... or shorting two outputs together -  with them fighting 
each other - one trying to pull it down and the other trying to pull it up

    Without being able see, and to get my hands on to the item and probe 
around that is difficult to diagnose, - not impossible, but difficult -

    However, while this looks bad on the CRO it appears to run OK in 
practise - correct? As I understand it your only real problem is the 
switch over,------ therefore I conclude that it is most likely something 
to do with the probing.

One other thought occurs - The chip you are probing the OE on - Are you 
sure that this is the active chip at the time, or is it the inactive 
chip? - With the probe connected try switching chips......its worth a 
try....
   

Good Luck
Bill

>
>Message: 3
>Date: Mon, 14 Feb 2005 00:01:27 -0500 (EST)
>From: mbelloli at speedymotorsports.com
>Subject: Re: [Diy_efi] Re: diy_efi Digest, Vol 17, Issue 11
>To: "A list for Do-It-Yourself EFI" <diy_efi at diy-efi.org>
>Message-ID:
>	<1070.24.7.39.231.1108357287.squirrel at www.speedymotorsports.com>
>Content-Type: text/plain;charset=iso-8859-1
>
>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
>  
>
>  
>
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