A call to arms

[scott.mohekey]

Hi all.. I'm looking for people with machine language/assembly code knowledge to help me in understanding the disassembled code in the 7202/7203 roms.

I've successfully disassembled nearly all of the code on a standard 7202 rom, and am so far able to identify a few things (some of the knock sum handling, for example).

My aim is to hopefully gain enough understanding of the code to be able to add features, such as launch control, and switchable maps.

What I'm proposing initially, is that we split the code up in to chunks, based on interrupts, each person going through the call tree of a single interrupt. This should go a long way to covering most of the code base.

If anyone is able and willing to help in this effort, please either pm me or leave a post in this thread.

[PaddyB]

I'm in. Tell me what you've found so far & where you'd like me to look.

[scott.mohekey]

I think we need to sort an easy way of sharing the information. I'm currently using IDA Pro, but I'm not sure how easy it is to share the databases it generates. Any ideas?

[wintertidenz]

I would really like to help, but I don't know disassembly or assembler code. Good luck with this Scott!

[scott.mohekey]

Dan, I'm sure you could help in some way. Did you end up getting that wide band? That would be a more than welcome donation

[mattnz]

I could probably give you a hand. Haven't done assembly for a while though.

[wintertidenz]

Scott - yes I did get the wideband, but I still need to buy the O2 sensor for it.

I'll visit some wreckers and see if I can get a few ECU's that I can start tracing back for you, and maybe get some trans ECU's as well so you can start plotting out those maps.
I might also end up getting a chip reader/programmer, I have all the apps I need to read the chips and design circuits... just need to play with them!

[scott.mohekey]

I've done a bit of research into disassembling the 7201 code as well, but without knowing exactly what processor it is, I didn't have much luck.

I also took the ECU out of my 96 auto st 25, only to find that it doesn't have a separate tcu and ecu. The one unit has TWO 7201s and two of the ST flash chips on it. I can only assume it handles both the engine and transmission. The wiring harness is also quite different.

[scott.mohekey]

Does anyone know roughly how launch control is implemented in other ecus/devices? At the moment I'm thinking of modifying the rev limit code to instead of check a single rev limit, check a table of rev limits indexed by vehicle speed. This would allow you to set sensible rev limits over a range of low vehicle speeds in an attempt at reducing wheel spin at those speeds. This is how I've seen it described on geekmapped.com.

[Patryn999]

Hmmm, haven't ever gone into the field of reverse engineering ECU's but I'm familiar with coding/assembly (obviously not the codes for the 7202, but I can do an ARM7 and most of atmel's AVR series) and would like to get into it.

Also just fitted a wideband to the car, so if you were to get it I'd have to drive round with no sensor in

If you want throw some dissasembled code my way and I'll start to familiarise myself with it and should be able to contribute shortly.

With respect to the launch control, I imagine it uses the same function that selects between the stationary/moving idle speed. You could add a branch to the rev limiter based on this, or a copy thereof (if you can find it). If not the official way I can't immediately see any pitfalls.

[scott.mohekey]

I'm going to try and figure out a way to make it easy for everyone to contribute and keep track of where everyone else is at tonight. Maybe a hosted wiki or something.

[mattnz]

I've got a 7201 and PFL A/T ECU lying around if you need them.

[scott.mohekey]

I've got some of these already thanks. The only one I don't have at the moment is a 7203.

[Patryn999]

Well in that case, you have my axe! (sorry, couldn't resist).

Hmmm, we probably need two aspects in that regard. Wiki's are good for discussion, but if your working on code we may want something like an SVN repository. Just makes local edits/commits 100x easier and you can see how other aspects are going as well.

I have no problem hosting something like that for this if you want a hand, I'm already running a 24/7 mail server for the UC climbing club in my cupboard.

[scott.mohekey]

I was thinking about that, but it really depends on what tools we use. IDA Pro isn't really suited to svn at all. It should be noted that I'm not disassembling the code into source files to be re assembled into the rom. I'm using IDA Pro which allows you to load the rom and show you what the op codes are in place. It also lets you comment individual instructions, etc. The problem is it stores all its work in a binary file along side the rom.

[Adam.Findlay]

scott in the idea of the greater good you can take my 7203 as long as you replace it with a ecu that will work, my car being manual and your spare being an auto ecu, i would love to be involved in this and learn how to re tune the car, although unfortunatly i think the level of computer literacy is way over my head.
And like i have said if i can get a hold of a wideband soon after my clutch gets sorted my car can be the lab rat for tuning as long as it dosent get damaged, haha,

[scott.mohekey]

The only ecu that I have more than one of at the moment is a 7201 (ignoring whatever is in my new car).

Actually, I'll list what I have:

7201 from 96 auto
7201 from 9x manual
7202 from 97 auto
720x currently in my 97 auto

I also have a 25 st auto e/tcu that has two 7201s in it.

I'm pretty sure that except for the 25 st ecu, the rest are largely interchangeable between auto and manual. I'm also pretty sure that you can interchange between cpu models too (i.e. use a 7201 in a car that came with a 7202).

[wintertidenz]

Scott - you can borrow the wideband controller provided you don't break it

You will need to get an O2 sensor though.

[scott.mohekey]

I think there's at least one wide band controller down here that Carl has (Patryn999). But thanks anyway.

[Adam.Findlay]

yip and carl can source the build your own kits easy enough, although id prefer to have a bought one rather then the home kit. but yeah i said to carl last time i saw him you two should collaberate with your skills and have a go at tuning. flick him a pm man