Timers on mpc8248 etc...

Alan Bennett embedded at akb.net
Thu Nov 29 10:41:22 EST 2007


I've got a routine that needs to delay for X microseconds, this is a
must.  The command after schedule_timeout must has to wait for the HW
to complete a task that takes X microseconds.

I would think that one way to do this is with a simple
schedule_timeout.  But in the example below, the time that passes from
run1() to dontrun() is far less than 3.2 msecs.  Infact, sometimes its
~ 800 micros according the a analyzer looking at points triggered in
run1() and donrun().  Could this be a configuration problem with the
timer/interrupt that generates the jiffies?


run1();
delaytime = 3280;
set_current_state(TASK_UNINTERRUPTIBLE) ;
schedule_timeout(usecs_to_jiffies(delaytime));  //1HZ = 1 second
1/1000 second = 1 milli
dontrun();



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