Hello Soo-Hyun Yoo,
Here I have RT_PREEMPT (3.0.8-rt23), we dont use the ioctl interface as
provided by ethercat master, but a similar scheme so I was curious...
Anyways, setting up a simple mini-usr-rt.c that *does* use the etherlab
API was easy - a simple digital-out square wave @1kHz (2000Hz bus
speed), signal checked on a scope, shows very little jitter - 1us. or less.
Regards,
Matthieu
On 03/05/12 15:59, Soo-Hyun Yoo wrote:
My tenuous understanding of this is that since the EtherCAT character
device tries to use the kernel's ioctl calls, the kernel's ioctl
"interface" (?) needs to be patched. Since RT_PREEMPT is the only patch
that does so, while LXRT provides its own interface, the former is the
only one capable of real-time user space operation while the latter is
limited to kernel space. Based on this assumption, I am hoping that the
EtherLab Master is capable of real-time operation in user space under
RT_PREEMPT.____
__ __
What can I do to lessen this jitter? Does anyone have a working EtherCAT
master running at 1 kHz with jitter under 50 us?
--
Matthieu Bec GMTO Corp.
cell: +1 626 354 9367 P.O. Box 90933
phone: +1 626 204 0527 Pasadena, CA 91109-0933
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