7747 tuning again

[Reid Bishop]

Ah, I see more clearly now (me thinks).  I was under the impression that
your reference to the 'service port' meant the ALDL interface.  So your
interface requires disassembly of the C3 box, and perhaps a bit of surgery
to the motherboards?  Or is there some kind of port inside that can be
accessed?

Now I'm really confused!


-----Original Message-----
From: owner-gmecm at diy-efi.org [mailto:owner-gmecm at diy-efi.org]On Behalf
Of rrauscher at nni.com
Sent: Thursday, September 28, 2000 8:56 AM
To: gmecm at diy-efi.org
Subject: Re: 7747 tuning again



There has been a few questions of how, when and where this tool
works. I'll fill in some.

First, I'd like to say that I can not take all of the credit
for this tool. Others have provided items such as ecm schematics
and software hac's that have helped immensely. The idea of
borrowing part of the bus cycle was mentioned on this group by
someone else about 2 yrs ago. I am just building on top of
information that others have provided. So credit all around.

I designed and built the data logger last Christmas, and have
been using it to tune. The other use has been to discover
a lot of how the '747 code works. It is a powerful tool to
be able to watch any and all cpu variables as the engine
and ecm goes through it's gyrations.

The circuitry is setup to mirror all of the ecm RAM. It does
this from the instant of turn on, through the entire running
of the ecm. In this manner, the exact same information that
resides in the ecm RAM, resides in the mirror ram. All of
this data is transmitted and captured. This includes items
such as BLM cells, SA variables, map, tps, O2, status
bits, timers, INT and proportional info, everything.
By capturing and saving the data, you can take your time
looking at it. No ram data is skipped or missed. Every cpu
write cycle to ram is mirrored.

The board plugs into the ecm service port, and is unknown
to the actual ecm. At a steady rate, the mirror ram data
is read and transmitted through a serial line to a laptop
for collection. It is a one-way transmission, no handshaking
required. When the ECM powers up, the tool starts to transmit.
Just grab and write the data to disk.

I plan to release everything required to build, collect and
analyse the data. The collection and display software is
written in C and runs under DOS. Source for the analysis/
display data will be released. The PIC software will also
be released. There are 3rd party libraries involved with
the collection software, so that I can only partially release
this portion. The executable will be released. (it's basically
a terminal emulator program).

The hardware can be built for ~$75. Everything else is free.
The reason that I'll releasing in a couple months is due to
both time constraints and the need to 'package' it.

I firmly believe that the release of this tool is in this
groups charter and good-will.

Thanks,

BobR.
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