Hello all,
I’m seeing a one timebase jitter with the timer function: with the
clockperiod set to 125 usec, and a timer configured to periodically trigger
every 1 msec, the timer occasionally doesn’t run until 1.125 msec later.
I’ve tried both pulse and signal notification methods. Any ideas?
Thanks,
Jim Sewell
Unico, Inc.
Jim Sewell <sewellja@unicous.com> wrote:
Hello all,
I’m seeing a one timebase jitter with the timer function: with the
clockperiod set to 125 usec, and a timer configured to periodically trigger
every 1 msec, the timer occasionally doesn’t run until 1.125 msec later.
I’ve tried both pulse and signal notification methods. Any ideas?
This is entirely expected, since the hardware can’t give you exactly
125 used – it will give you the largest integer multiple of the underlying
quartz-chip frequency, and occasionally this error catches up with you.
Take a look at:
http://www.qnx.com/developers/articles/article_826_2.html
for a more detailed explanation.
A work-around:
Set your clock period.
Query what you got.
Set your repeating 1ms timer to not be 1ms, but 8 times whatever your
125 usec tick actually is.
David Gibbs
QNX Training Services
dagibbs@qnx.com
Evan Hillas wrote:
David, I hope that’s your machines date-stamp that is out by more than
an hour and not some oddity of Usenet?
I’m more inclined to believe it is your machine. I’m writing this at 16:11 EST and the timestamps on
your two posts are 16:41 & 17:07, respectively, while David’s is 15:37.
Kevin.
Kevin N wrote:
Evan Hillas wrote:
David, I hope that’s your machines date-stamp that is out by more than
an hour and not some oddity of Usenet?
I’m more inclined to believe it is your machine. I’m writing this at
16:11 EST and the timestamps on your two posts are 16:41 & 17:07,
respectively, while David’s is 15:37.Kevin.
Opps, heh, I had daylight saving turned off. 
Evan Hillas wrote:
Opps, heh, I had daylight saving turned off. >
A side-effect of experimenting with license re-activation …
Jim Sewell wrote:
Hello all,
I’m seeing a one timebase jitter with the timer function: with the
clockperiod set to 125 usec, and a timer configured to periodically trigger
every 1 msec, the timer occasionally doesn’t run until 1.125 msec later.
I’ve tried both pulse and signal notification methods. Any ideas?
Completely normal and well documented by QSS.
Read the following for a good summary: http://www.openqnx.com/PNphpBB2-viewtopic-t3105-.html
Evan
David, I hope that’s your machines date-stamp that is out by more than an hour and not some oddity of Usenet?
Evan