Well the good news is that someone already did the hard part for us!
The Linux kernel includes since several versions the support to the can protocol and provides what seems to be a very easy interface to it. It's called SocketCAN and it is modeled after the standard unix socket API.
The project page is at BerliOS and hosts the kernel patches (not needed anymore as it is included in mainstream) and some user space tools that I just downloaded and installed without a glitch. You can get them by accessing the project subversion repository with this command: svn checkout http://svn.berlios.de/svnroot/repos/socketcan/trunk canbus
More info on what is and how to use SocketCan can be found in the linux kernel documentation directory (available on the web here)
As for the device drivers, SocketCAN supports a few drivers alreay, two of which are particularly interesting: vcan and slcan. Vcan is a virtual CAN interface driver and is there for testing when there is no hardware available. This will be probably the first to try once I realize how the user space utilities work. The slcan driver is "For a bunch of CAN adaptors that are attached via a serial line ASCII protocol (for serial / USB adaptors)" and should match exactly what we are trying to do. I just wonder what is the data format the slcan drivers expects to receive from the serial port. I have only found a strange document here so far but the semantic is not clear to me and I will have to investigate this further.
Sunday, June 14, 2009
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