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Ginkgo USB-CAN Interface Part 2

Posted 02-20-2018 at 07:50 PM by Indymaynard
Updated 03-04-2018 at 03:43 AM by Indymaynard

The lack of documentation on this thing is obnoxious. Tenacity might be the only thing to get me through this. If you haven't seen my previous post (if you care), I am trying to write some software to use the Ginkgo USB-CAN interface on my 2007 Jeep Grand Cherokee. The Ginkgo (I am going to shorten it to this, since it should be pretty obvious what I am talking about) has a PDF associated with it on the Viewtool website which details the API's, though it does a confusing job of it. I should also add that there is some significant importance to knowing the baud rate of your CAN bus, and this is what had me stuck for a long time. There are some places on the internet, most specifically the work done by Chad Gibbons, that mention the 2013 Jeep CAN bus in his runs at 125 Kbps. I made a bad assumption that my 2007 would have had the same baud rate.

After referring to a Chilton's Manual on my particular model, I discovered that my CAN bus runs at 83.33 Kbps. This is great, except that the closest preset to this in the Ginkgo USB-CAN Extend software available on the Viewtool site is 80 Kbps. That is a pretty significant difference. I received some data, but it was more intermittent than I knew I should be getting. Oddly enough, the data was consistent when I received it. It was obvious that it wasn't correct, but this certainly got me farther than I had gotten before, and that was refreshing.

Something that should have seemed a little obvious was the menu entry in the bit rate settings that were written in Chinese. When this menu opened, I was able to input custom values for BS1, BS2, SJW, and BRP. I have not searched for the meanings of these, but the manual gives a few tables to help you decide, including examples for those common rates it has listed in the menu. That was not how I proceeded, mostly because I can be a little impatient. My solution was to plug in some values until I found what it was that I wanted, and the software instantly calculates for you. I found that most helpful. Here are the settings if you have an 83.33 Kbps CAN bus:

BS1 = 4
BS2 = 1
SJW = 1
BRP = 72
Data started pouring in when I set these values. What the data means is quite another problem to solve, but I saved the data to some CSV files for analyzing, and I should be able to refer to the Chilton's manual for some info. At least there has been some progress.
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