Re: [Xenomai] RT-CAN question (was: CAN bus on beaglebone black)

[Wolfgang Grandegger <wg@grandegger.com>]

On 03/19/2015 10:57 AM, Michael Haberler wrote:
> status:
> 
> I have Steve Batazzo's driver running on the beaglebone, using a stock
> Xenomai kernel from Robert Nelson's repo (linux-image-3.8.13-xenomai-r71
> from http://repos.rcn-ee.net/debian/), current driver out of tree at
> https://github.com/mhaberler/rtcan-bb branch mah
> 
> I also have a preliminary HAL driver for machinekit which talks to a
> Trinamic motor over RT-CAN just fine (beaglebone for now, x86 once I get a
> CAN PCI card).
> 
> I'm working with Steve to get the driver polished and hope we can inject it
> into the Xenomai foodchain eventually, after which it will be eventually
> picked up by Robert's periodic builds, and the whole thing becomes an
> 'apt-get install' - affair. But we're not there yet.
> 
> 
> I have a few questions on RT-CAN (I guess really RTDM):
> 
> - can the RTDM API (
> https://xenomai.org/documentation/trunk/html/api/group__userapi.html) be
> used from a normal Posix thread (non-RT) just alike? from the rtcansend*
> utilities src it looks like at least for setup, even if the send/receive
> ops are done in an RT thread.
> 
> - socket-CAN and RT-CAN interworking: I assume this is an either-or affair,
> right? (background: for some jobs the RT-CAN features are overkill, and in
> that case something like the python-can binding would be convenient to use)

If the resources (irq, mem, etc.) used by the device are clearly
separated, it might be possible to use one device (of the same type) for
Linux and the other for RTCAN. It will work for sure for devices using
different drivers (belonging to different controllers).

Wolfgang.