E92 PCM Reverse Engineering

[gmtech825]

is there a free, easy to setup and use ppc compiler out there for windows? I haven't had any luck finding one.

[bubba2533]

This is what I'm using. https://gnutoolchains.com/powerpc-eabi/

[bubba2533]

Anyone ever use one of the cheap OBD2 splitters? It seems like having 2 instances of UP and two cables might be quite helpful for debugging. It seems like something that would be hard to have an issue with, but I figured I would ask anyway.

[ironduke]

Anyone ever use one of the cheap OBD2 splitters? It seems like having 2 instances of UP and two cables might be quite helpful for debugging. It seems like something that would be hard to have an issue with, but I figured I would ask anyway.

I use a y cable all the time With mdi’s.. works good using a logger on one and you can run sps2, or tech2win, or gds2 on the other one and you can get a good log of the commands/responses..

Only snag I’ve run into is my logger program glitches sometimes when I’m reading low speed lan pin 1. I have to start a log of high speed,disconnect,then reconnect to low speed in order to read data..

[Gampy]

I also use an OBDII Y-spliter cable, works as it should ... I do recommend buying one you can disassemble the connectors on, don't get a molded one, it's nice to be able to pull them apart and tighten the female wire ends for solid connections.

I have this one: Amazon.com bbfly B11 OBD2 Y-Splitter
I need a second one, so this one is in my waiting list for my next Amazon purchase: Amazon.com bbfly B6 OBD2 Y-Splitter

-Enjoy

[bubba2533]

I also use an OBDII Y-spliter cable, works as it should ... I do recommend buying one you can disassemble the connectors on, don't get a molded one, it's nice to be able to pull them apart and tighten the female wire ends for solid connections.

I have this one: Amazon.com bbfly B11 OBD2 Y-Splitter
I need a second one, so this one is in my waiting list for my next Amazon purchase: Amazon.com bbfly B6 OBD2 Y-Splitter

-Enjoy

I didn't even think about disassembling, but luckily the second one you linked is the one I bought!

[bubba2533]

Ok, well I've had a big win. I've been able to write my own transmit frame function and it's finally working as expected.

I was really worried that I wasn't going to figure it out, but it was just me getting in my own way.

This just shows a loop that is sending out some debug information from the FLEXCAN registers. I only have it working with sending out single frames (7 bytes max), but that will have to get modified to handle larger payloads at some point.

Write_Frame_Test.JPG (148.92 KiB) Viewed 1391 times

I think the next big thing would be to write a working receive function. Right now I'll start with receiving single frames like I did with the transmit function.

[bubba2533]

It's done!

It's just a simple echo of what I send to the PCM, but I'm pretty happy right now.

E92 Tx_Rx_Kernel.JPG (118.89 KiB) Viewed 1348 times

[antus]

Congrats, well done!

[Tazzi]

It's done!

It's just a simple echo of what I send to the PCM, but I'm pretty happy right now.

E92 Tx_Rx_Kernel.JPG

Woohoo!!! Love it!
Couple things to note for you:
1) There is a max of 8 bytes you can send per CAN frame (I see 7 is sent in your examples).
2) To send larger chunks of data, these are still split into 8byte frames, but must be in a very specific format to meet the SAE standard to use with J tools.