This utility is designed to work with any vehicle that is exposed on the local machine as a CAN network interface. Therefore, any OBD-II adaptor that exposes itself as a CAN device can be used. For example, the PiCAN2 is such an adaptor for the Raspberry Pi. Linux supports a family of sockets specifically for CAN communication (the PF_CAN protocol family), which we leverage in our utility.
- Clone this repo:
git clone --recursive git@github.com:ejvaughan/cse521.git cdintosrc/and runmake- The command-line utility is named
car_localand will be placed into thebuild/subdirectory.
The utility uses the ISO-TP protocol for its socket communication (as opposed to using the "raw" CAN protocol). This protocol is implemented in a kernel module, but unfortunately the module has not yet been merged into the linux trunk. The code for this module is available in a separate Git repository and is checked out when you run git clone --recursive git@github.com:ejvaughan/cse521.git.
Before you can run the utility, the kernel module must be built and installed. The module's README.md (located at can-isotp-modules/README.md) has instructions for how to do this.
The command line utility can be invoked as follows:
Usage: car_local -t <transfer CAN ID> -r <receive CAN ID> <CAN interface>
<transfer CAN ID>: The CAN ID that will be used for sending the diagnostic requests. For 11-bit identifiers, this can be either the broadcast ID, 0x7DF, or an ID in the range 0x7E0 to 0x7E7, indicating a particular ECU.
<receive CAN ID>: The CAN ID that the ECU will be using to respond to the diagnostic requests that are sent. For 11-bit identifiers, this is an ID in the range 0x7E8 to 0x7EF (i.e. <transfer CAN ID> + 8)
The particular IDs used for sending/receiving will be dependent on the vehicle. Most vehicles will use the IDs explained in the usage message above. However, some vehicles use extended (29-bit) identifiers. For example, for a 2009 Honda Civic, the transfer ID must be 0x18DB33F1, and the ECU will respond with an ID of 0x18DAF110. Therefore, the utility will be invoked like so:
car_local -t 18DB33F1 -r 18DAF110 can0
Right now, the utility has limited functionality. Every second, it sends an OBD-II request for the engine RPMs, and prints the response to stdout. As development continues, additional functionality will be added.