Re: [ECOS] cyg_flag_timed_wait doesn't seem to work as expected

[Nick Garnett <nickg@calivar.com>]

On 27/05/16 14:30, Michael W. Ellis wrote:
> I'm running an old version of eCos (2.0.98) from eCosCentric and I'm
> attempting to use cyg_flag_timed_wait to periodically update a
> display (see code, below).  My event flag variable g_flags is
> initialized elsewhere before this thread is created.  Other threads
> access the same event flag but use their own bits within the flag.
> 
> My problem is with the timed wait behavior of the event flag.  At
> startup I see an initial wait of 30 seconds before the first display
> update occurs, but the update occurs continually after the initial
> timeout.  The local variable flags always reads 0, indicating timeout
> has occurred.  My understanding is that calling cyg_flag_timed_wait
> at the top of the loop restarts the timer, but this does not seem to
> be the case.  What am I missing here?  Is there something I must do
> to clear the timeout event?
> 

The problem is your use of 3000 for the timeout. In eCos, timeouts give
the wakeup time, not the duration. So, the first call waits until tick
3000, but the rest return immediately since it is now past 3000.

The solution is to use cyg_current_time()+3000 in the timeout argument.

-- 
Nick Garnett                                         Kernel Architect
eCosCentric Limited    http://www.eCosCentric.com    The eCos experts
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