Re: [Xenomai-help] State of implementation of CAN, CANOpen in Xenomai

[Wolfgang Grandegger <wg@domain.hid>]

Berruer Sébastien wrote:
> Hello,
> 
> I'm reviewing the feasibility of a project that would require the driving of
> devices with real time constrains.

OK, then RT-Socket-CAN is a good choice.

> I'm asking for the current state of the CAN implementation. Is it a
> partial or a
> complete implementation of the CAN standard? What are the guarantee
> about real
> time latency?

What exactly do you mean with CAN standard? RT-Socket-CAN allows
low-level access the CAN controller to send and receive messages, handle
errors and set the bit-timing. Standard, extended and RTR frames are
supported.

> I explored briefly the sources of Xenomai, and I read the file
> "ksrc/drivers/can/README". Is it up-to-date? Is there really only
> support for
> the controllers listed in it?

Mainly yes, what CAN controller would you like to use? Writing a
RT-Socket-CAN driver is usually not a big deal.

> I've read in "RTDM and applications" that there would be an effort for
> implementing a CANOpen profile. But, the implementation of CANOpen
> protocol is
> let to users? I can't find any newer reference for that in sources or in the
> documentation of Xenomai. What is the state of this project?

If you are looking for a free CANopen implementation, CANfestival might
be an option, which also supports RT-Socket-CAN, IIRC. Check
http://canfestival.org/ for further information.

> I've seen that there is currently only one implementation of a RT driver
> for the
> 16550A serial controller. Has anybody implemented it for other chip?

What chip/hardware do you have in mind?

> If I finally decide to choose a RT-Patch, instead of Xenomai, I will
> have the
> CAN implementation that will use the Linux networking stack. But I will
> not have
> any guarantee about its real time implementation, isn't it?

The Linux network stack is not hard real-time capable and the real-time
preemption patch will only help partially.

Wolfgang.