OBD2 LT1 XDF $EE EEX creation

[Terminal_Crazy]

The quick answer is no. You can clear, or set, even a bit of a byte. A little bit longer answer(see what I did there? ) is did you correct the checksum for the change you made and the CEL is flashing rapidly cuz it is very unhappy

Yeah but you could recalc the checksum & update that byte.

The software could do a compare of your old file vs new file and write just that. If much has changed, that would probably be futile, time wise.

Steveo's EEHack does to a small extent

Shit, you could write an idling bootloader, disable the checksum, send executable packets and almost have real-time emulation. Ummmmm this IS freeware, right?

Great, will that be ready by tea time? :-)

I wish I knew more about these sytems, so I appologise if I throw in some random comments

There are a few of us who do follow these discussions even if we're sat here with a dumb expression on our face sometimes.
If the processors were ARM based, i'd be able to follow some of the dissassembly better.


Mitch

[Tom H]

Yeah but you could recalc the checksum & update that byte.
Mitch

If you need to fix a checksum, just program an un-used $FF location anywhere within the checksum range such that the sum is fixed. Harder if it is 16bit, you then need to mess with 256 locations. Still, up high there are largeish blocks of blank.

-Tom

[Tom H]

Hi,
I have completed my look through the '96-7 Tside FLASH programming code & commented the operation. The comments are best efforts only, I hope they are of use to you.

Big thanks to kur4o for his help with the tricky bits.

-Tom

[Tom H]

Hi,
I have completed my look through the '96-7 Eside FLASH programming code & commented the operation. The comments are best efforts only, I hope they are of use to you. It is interesting to look at the Programming Exec which has a mode (upload $35) that is new to me. I am thinking to write code for the upload section, but first I am planning to test my theory on an easy way to unbrick.

I am posting the Tside again, this time with a correction where code was cut out.


-Tom

[kur4o]

Nice work on the comments, much better to understand and complete.

Mode 35 is a built in mode for reading bin over odb2 port. Some of the earlier obd2 pcms have that built in the code, but later it got removed.

[Tom H]

I need some confirmation....

Message format over aldl is [DEVICE ID] [LENGTH] [MODE] [MESSAGE …] [CHECKSUM]

for mode $06 and message $55, does this mean command in progress, not completed yet?

THX -Tom

[steveo]

yep, or in other words just to tell the tester 'wait until next message'

in practice, the only code that seems to use it is the erase routine (being the only code that could potentially run long enough to need it)