Tunerpro automatically calculates checksum? Really?

BrendanSmall · Post by **BrendanSmall** » Wed Mar 03, 2010 4:01 am

I'm a little confused here. I've read that tunerpro automatically corrects the checksum, but I don't see how or where it does so? All the XDFs I've downloaded to check out the Checksum scalar have no 'conversion' calculation in them, so it seems to be primarily a viewer. I'm assuming that I'm off my rocker here, but just in case I'm not...anyone have any info?

I'm primarily working with an older VW management (digi-1) that has no need for checksum correction, but am branching out to Motronic 2.9 (32kb version, 4 cylinder engine not VR6) and am encountering very little info about the checksum I need to calculate. The VR (64kb) file is well documented, and WinOLS has a plugin for it...but the 4 cyl (32kb) file has no such plugin available (WinOLS says nothing available). I haven't tried to work without changing the cks yet, since I don't have a car to test on, but it's better to be prepared.

Post by **robertisaar** » Wed Mar 03, 2010 5:16 am

in the scalars list, there may or may not be a checksum item, but in the XDF header, there is info and settings there that allow TP to calc and update the checksum automatically anytime a change is made.

BrendanSmall · Post by **BrendanSmall** » Wed Mar 03, 2010 6:18 am

I'm assuming that I have to enter this info before it can start to work though?

Post by **robertisaar** » Wed Mar 03, 2010 6:25 am

BrendanSmall wrote:I'm assuming that I have to enter this info before it can start to work though?

if the XDF was already made, you wouldn't have to worry about it.

if YOU are making the XDF, then yes, you need to fill all of the XDF header in before attempting anything else.

BrendanSmall · Post by **BrendanSmall** » Wed Mar 03, 2010 6:35 am

Cool, exactly what I wanted to know, thank you very much.
I'm writing the XDF, so I guess I'd better expend some energy on finding that checksum!

Quattro · Post by **Quattro** » Mon Mar 15, 2010 9:37 am

Hi there guys,

Howdo you get TP to perform the not function for the checksum , it only does 1's and 2's compliment apart from addition

Post by **Mangus** » Mon Mar 15, 2010 9:14 pm

Quattro wrote:Hi there guys,

Howdo you get TP to perform the not function for the checksum , it only does 1's and 2's compliment apart from addition

This is something that would need to be added. however, your checksum is even more complex. Hopefully we can find a solution down the road.

Quattro · Post by **Quattro** » Mon Mar 15, 2010 9:22 pm

Hi Mark,

Ok, I get that one, hopefully you can assist with that module for the xor function. How do I disable the checksum during emulation, that is my main problem. Since my checksum resides over two adresses in the form of 16bit and the xor of the checksum in another two adresses . Am I makin sense here ?

Post by **Mangus** » Mon Mar 15, 2010 9:53 pm

Probably depends on the Bosch code. Is it possible? You tell me.

Quattro · Post by **Quattro** » Mon Mar 15, 2010 10:14 pm

What do you need to know ?

Post by **Mangus** » Tue Mar 16, 2010 8:24 am

Quattro wrote:What do you need to know ?

If the code on the ECU has a "Disabled checksum" mode. If it does, then you don't need to worry about the checksum calculation at all.

Quattro · Post by **Quattro** » Tue Mar 16, 2010 8:45 am

Mark,

I am not sure of this. Can I send the bin to you ?

Post by **Mangus** » Tue Mar 16, 2010 9:15 am

Quattro wrote:Mark,

I am not sure of this. Can I send the bin to you ?

I couldn't help determine whether it does. You would need diassembled and commented code to figure it out.

slappynuts · Post by **slappynuts** » Fri May 21, 2010 3:08 pm

Lets start out with the 93-95 OBD1golf/jetta chip file.Everybody get it downloaded and we will start here.

http://www.bifpowell.com/motronic/TP,obd12l,stock.dat

Now open up your hex editor(winhex) and open up the file.The first thing we need to do is find the checksum and be able to recalculate it.

The checksum in most motronic chip files is by the file ID tag.This is usually located after most of the code and the maps in the file(we will get to that later).In this case its at CF00 and CF01.The checksum is a 16bit checksum and is the total of the block from 0000-CEFF.If you click edit- define block and type in the 0 for the start of the block and CEFF for the end of the block the hex editor will highlight that part of the chip file.Now you have the block selected to checksum.Click tools-calculate hash.On the drop down pick 16bit and then OK.That will spit out the checksum of the block.You will also notice this matches the locations CF00 and CF01.