This directory contains source code for new CAN/CAN FD stack for RTEMS. Currently, the stack can be tested against two targets: virtual CAN and CTU CAN FD soft core. Following sections describe compilation steps required to build RTEMS application either on Xilinx-Zynq board or on i386 architecture with virtualization over mainline x86-64 QEMU.

The subsystem is based on the concept of original LinCAN (Linux CAN) driver which has been developed as the part of OrtCAN project.

The API to the driver is provided in the form of the POSIX character driver. Each CAN controller (chip) is registered as node into "/dev" namespace by name (i.e. "can0", "can1", ... ). It can be open multiple times and each instance of the open can be accessed from the multiple threads. Written messages are post into input end of queue (FIFO) which is connected to the can controller (chip) or other frame processor on the output side. Processor takes frames from FIFOs according their priority class and transmit them to the network. When frame is successfully sent it is echoed bask to all queues back to open file instances except the sending one (that filtering is configurable) and these where given frame is filtered out. Received frames a filtered to all queues to applications ends of the queues which filter matches the CAN identifier and frame type.

RTEMS CAN Test Compilation

CAN Stack can be currently tested on Xilinx-Zynq MzAPO board or on i386 target using mainline x86-64 QEMU.

i386 using QEMU

You can test our CAN stack using mainline QEMU qemu-system-x86_64 by compiling the application for i386 target. Following steps are required to run the application using QEMU.

$ export PATH=$PATH:/opt/rtems/6/bin
$ cd targets/i386_pc686
$ ./setup-host-socketcan #might be required with sudo
$ ./qemu-i386-pc686-2x-ctu-pci-build
$ ./qemu-i386-pc686-2x-ctu-pci-run

It is expected that support for i386_pc686 is located in /opt/rtems/6. You can use following script to compile BSP with required settings.

$ ./i386-rtems-sys.cfg

Note that you might need to modify path to RTEMS source code directory in RTEMS_DIR variable.

Both virtual CAN and CTU CAN FD targets can be tested on i386.

Xilinx-Zynq MzAPO board

Compilation steps for Xilinx-Zynq:

$ export PATH=$PATH:/opt/rtems/6/bin

$ make

It is expected that Xilinx BSP is build at /opt/rtems. You can use following link https://gitlab.fel.cvut.cz/otrees/rtems/work-and-ideas/-/wikis/home to compile RTEMS for Xilinx step by step or scripts located in targets/xilinx_zynq_mz_apo directory,

RTEMS CAN Test Commands

There are two test applications available: can_1w and can_2w. First application sends messages from one device to other while the second one transfers messages both ways. Devices have to be specified first.

Command can_register -t [target] registers supported CAN controller based on argument -t. Argument -h can be used to list currently supported targets. Controller is registered as a characteristic device on path dev/can0, dev/can1 etc.

Command can_set_test_dev [dev0] [dev1] set targets for CAN test applications.

Running Tests for CTU CAN FD

Following steps can be used to run CAN applications for CTU CAN FD controller target.

# this registers two CTU CAN FD controllers under dev/can0 and dev/can1
SHLL [/] # can_register -t ctucanfd
# assign dev/can0 and dev/can1 to test applications
SHLL [/] # can_set_test_dev /dev/can0 /dev/can1
# run test applications
SHLL [/] # can_1w
SHLL [/] # can_2w

The same approach can be used for virtual controller.