[Diy_efi] Continuing the chip switcher "problem"

Tue Feb 15 07:34:53 GMT 2005

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Marcello,

I'm not experienced with the MCU's in use in your ECU, but widely  
experienced in the old 8-bit families from various manufacturers, and  particularly 
those used in the old 8 and early 16-bit computers.  In all of  these, the 
E(E)PROM OE bar line was derived from logic circuitry designed to  sense when that 
particular part of the memory map was being accessed, often in  conjunction with 
the "READ" signal.  So not only did you have to be looking  at that part of 
the memory map, you had to be trying to read it also.

With your OKI MCU however, because most of the accessing of the memory map  
is inside the chip, there is a possibility that OE bar is driven from one of 
the  chip's output ports.  You will just have to trace it back patiently I  
think.  Good luck.

Will

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<DIV>Marcello,</DIV>
<DIV>&nbsp;</DIV>
<DIV>I'm not experienced with the MCU's in use in your ECU, but widely=20
experienced in the old 8-bit families from various manufacturers, and=20
particularly those used in the old 8 and early 16-bit computers.&nbsp; In al=
l of=20
these, the E(E)PROM OE bar line was derived from logic circuitry designed to=
=20
sense when that particular part of the memory map was being accessed, often=20=
in=20
conjunction with the "READ" signal.&nbsp; So not only did you have to be loo=
king=20
at that part of the memory map, you had to be trying to read it also.</DIV>
<DIV>&nbsp;</DIV>
<DIV>With your OKI MCU however, because most of the accessing of the memory=20=
map=20
is inside the chip, there is a possibility that OE bar is driven from one of=
 the=20
chip's output ports.&nbsp; You will just have to trace it back patiently I=20
think.&nbsp; Good luck.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Will</DIV>
<DIV>&nbsp;</DIV></FONT></BODY></HTML>

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