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CAN communication

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Hey Andre this is an area that I am really interested in developing. I just watched the introduction video and the second one and I have a question. Say I have a racepak IQ3 and an AEM ecu can I change what the AEM outputs to match what the racepak wants? I am thinking that would make the cost of the race pak more palatable to my customers. I have understood what you taught I just was wondering if I Can change what the ecu is outputting. Thank you

What you can do is very dependent on the particular ECU and most ECUs don't allow end user configuration of the CAN bus template. The AEM Infinity and Haltech ECUs are two examples where the CAN transmit template is fixed and we can't change it or add specific parameters. Likewise the IQ3 is very locked down and you need to purchase the specific CAN adaptor for your ECU in order to get the data into the dash.

This is one of the reasons I'm a big fan of the Motec range of dashes - They're probably some of the most flexible in terms of end user configurability for both receiving and transmitting CAN messages. They do however come at a significant price premium over the IQ3.

I have been looking at this company called GaugeArt their prices are not that bad. But hopefully After you guys bring that course out I will be verse enough to be able to do some reverse engineering.

following suit with the topic below,

Is there any program or software stack that will tell you the arbitration field to determine if the information is being sent in a base frame format or extended frame format?

Is there any software that determines if the can frame is being bitstuffed?

and is there any software that offers the ability to read the entire can frame in binary? (consequently answering my prior question about bitstuffing)

i've forced myself to learn linux and understand the can-utils package and other linux offerings to decode the diagnostic bus on my daily driver. it's helped me a great deal and i've been using vokoscreen for recording/logging information so i can view it later.

Hi mitchdetailed,

I'm using Microchip's CAN bus analyzer. This will indicate extended message by adding a postfix "x" on the ID. See attached pic. I feel that I should mention that I'm not thrilled with Microchip's software, but it does the job.

I don't know any software that will automatically detect bitmapped (or bitstuffed) bytes. I don't think that is possible for an analyzer software to do, as it need more information. The procedure for finding the bit is pretty much the same as Andre explained in the webinar; locate the byte, then locate the bit. F. ex. if you see a byte toggling between 38 to 3A, then it would be the second bit in that byte.

I hope this helps.

Attached Files

it most certainly did help, i'm personally using linux and can-utils, which most probably aren't too interested in, although i've found it incredibly handy (and FREE)

one of the best parts about it is i dont have to read the bus in hex, I can switch on the fly between binary and hex, refresh speed, red marker time for changing values, and if i want to eliminate id's that aren't noticing a change on the bus at all, it'll clear them from the list. i'll post up a screen shot following this. definately helps when 1 bit in a byte sequence changes, but is associated with the variable. (wheel speed is an easy example for me, on my benz if the wheels are rotating forwards, the first bit of a 2 byte sequence changes, and reverse the second bit of a 2 byte sequence changes, the other 14 bits are assigned to wheel speed information)

Attached Files

Interesting CAN message you found in your Merc. Is it normal that the car makers use custom data types, and merges data types in a byte or word?

Sound like the can-utils have some nice features. Too bad I'm trapped in the world of Bill Gates. For me, using anything other than windows is equally awkward as small-talk to non motorsport enthusiast. I can't even thread a shoelace without setting up a spreadsheet in Excel (better to do the math beforehand, rather than finding out that the shoelace is too short in the middle of the job). :)

The data (tjst I've been able to decode) is all relatively basic. Theres a bunch of can ids that appear to be some sort of timer based function that just roll through the hex values. Some flashes 0's then 1s over and over again. If you're referring to the characters on the right side, i believe its the ascii converted format of the message. (how it comes up with the conversion im unaware of lol)

Im a pc guy myself, but after getting a copy of the car hackers handbook 2016, and watching the authors YouTube videos, I installed a dual boot and started digging for answers and information.

https://m.youtube.com/playlist?list=PLBqtCp9s_lnEOtf6I1DDMEANIzJJLXRhe

Those 4 videos are pretty much where my knowledge is. I use a program called Vokoscreen to record microphone audio and the screen so ill log parameters via video. And if I had to go back and do it over, id be able to purchase all the hardware for about 80$ excluding a laptop to log the bus. Comparing that to the price of most windows based systems definitely changes things for the hobbyists