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RE: 1228331 ECU Processor (P4 processor info)
Don't want to be a pain, but my ECU would appear to have RAM from
0x0000-0x02FF. Many parts of the code use variable storage in the 0x03XX
area of memory. Also, one of the first instructions after reset is "lds
#$02FF", which I think means load stack pointer = 0x02FF, so I'm assuming
the stack works down from there. I have no way of knowing how much of this
RAM is battery backed up, perhaps only the first 256 or 512 bytes. There
are no references to anything from 0x0300-0x2FFF, although when I dumped
this area of memory I got images of 0x0000-0x03FF in parts of it. (GM
saving money by incomplete address decoding ?)
The code makes reference to some hardware? in the 0x3000- 0x30FF area. The
values in these locations get transmitted as part of the ALDL data stream.
And like Peter, the code writes to hardware? in the 0x3FF0-0x3FFF area as
well.
The registers in the 0x4000-0x400C area seem to tie up correctly.
If anybody is interested, I can EMAIL them the contents of my ECU's memory
map from 0x0000-0x7FFF. The EPROM (0x8000-0xFFFF) is allready on the ftp
incomming site.
Thanks for the help so far
Malcolm Robb, LC 0112G
-----Original Message-----
From: steve ravet [SMTP:sravet@arm.com]
Sent: Tuesday, April 11, 2000 10:45 PM
To: gmecm@diy-efi.org
Subject: Re: 1228331 ECU Processor (P4 processor info)
Peter Gargano wrote:
>
> According to the disassembly of BUA, here are some other locations
> that Steve has not mentioned at:
They're on there now. Do you have any more info about the region
3cf0-3fff? I'd like to fill it in a little more. Does the HUD code really
fit from 5800-58ff?
* steve
>
> http://www.diy-efi.org/gmecm/ecm_info/p4_registers.html
>
> $04xx Heads up display (HUD) RAM variables (if present)
> $3fC0-$3fff Other hardware registers controlling peripheral devices
> $58xx HUD code (if present)
>
--
Steve Ravet
steve.ravet@arm.com
ARM,Inc.
www.arm.com
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