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RE: which priority will suit rtc clock?


On Wed, 2002-10-16 at 08:59, Qiang Huang wrote:
> I meant the Real Time clock will also generate a clock tick interrupt,
> right?
> for example :
> 
> (lowest priority number, highest  priority)
> 
> ext_IRQ2 with higher priority than ext_IRQ1
> ext_IRQ1: priority: 5
> ext_IRQ2: priority: 3
> Real Time Clock Tick Interrupt: priority: ??
> 
> When ext_IRQ1 happened and being processed, at the same time ext_IRQ2
> happens, will it process the ext_IRQ2 or  while processing ext_IRQ1 all
> interrupt are masked so not able to response to ext_IRQ2?? if ext_IRQ2 would
> be processed because of its higher priority than ext_IRQ2 then which
> priority should be used for real time clock tick interrupt(assume RTC
> priority can be adjusted)? Or am I wrong for all of this?
> 

How this behaves depends on your hardware.  Some systems have pure
priority based interrupt systems which would behave more or less like
you've outlined.  Most modern systems have interrupt controllers which
allow individual interrupt sources to be enabled/disabled separately.
In systems such as this, only the interrupts being serviced are disabled
(during the service) and other interrupts can still be presented to 
the system.

Whether your system contains a "real time clock" which generates 
interrupts in addition to the system "heartbeat clock" is also platform
dependent.  eCos only needs the presence of a heartbeat, which is 
sometimes incorrectly referred to as the "real time clock", but in
reality it is just a source of periodic interrupts which is used by
the system for timing.

> Thank you very much.
> 
> -----Original Message-----
> From: Gary Thomas [mailto:gthomas@ecoscentric.com]
> Sent: 16 October 2002 15:43
> To: Qiang Huang
> Cc: eCos Discussion
> Subject: Re: [ECOS] which priority will suit rtc clock?
> 
> 
> On Wed, 2002-10-16 at 08:39, Qiang Huang wrote:
> > Thank you.
> > If irq is being processed, should the rtc interrupt still work? If so does
> > that mean the rtc interrupt priority should be the lowest  compare to
> other
> > irq.
> 
> I have no idea what you are trying to ask here.
> 
> > Thanks a lot.
> >
> > -----Original Message-----
> > From: Gary Thomas [mailto:gthomas@ecoscentric.com]
> > Sent: 15 October 2002 14:09
> > To: Qiang Huang
> > Cc: eCos Discussion
> > Subject: Re: [ECOS] If delay() function is called in an isr() with
> > interruptdisabled...
> >
> >
> > On Tue, 2002-10-15 at 05:25, Qiang Huang wrote:
> > > Hi all:
> > >      I wonder which priority should the RTC be? If the delay() function
> > > depends on the system RTC so if it is called in an isr() (which with
> > > interrupt disabled) anything wrong?
> >
> > You can't call any function which depends on interrupts (or even higher
> > level scheduling) from an ISR.
> >
> > > Thanks a lot
> > > qiang
> > >
> > >
> > >
> > > --
> > > Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
> > > and search the list archive: http://sources.redhat.com/ml/ecos-discuss
> >
> > --
> > ------------------------------------------------------------
> > Gary Thomas                  |
> > eCosCentric, Ltd.            |
> > +1 (970) 229-1963            |  eCos & RedBoot experts
> > gthomas@ecoscentric.com      |
> > http://www.ecoscentric.com/  |
> > ------------------------------------------------------------
> >
> >
> >
> >
> > --
> > Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
> > and search the list archive: http://sources.redhat.com/ml/ecos-discuss
> --
> ------------------------------------------------------------
> Gary Thomas                  |
> eCosCentric, Ltd.            |
> +1 (970) 229-1963            |  eCos & RedBoot experts
> gthomas@ecoscentric.com      |
> http://www.ecoscentric.com/  |
> ------------------------------------------------------------
> 
> 
> 
> 
> -- 
> Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
> and search the list archive: http://sources.redhat.com/ml/ecos-discuss
-- 
------------------------------------------------------------
Gary Thomas                  |
eCosCentric, Ltd.            |  
+1 (970) 229-1963            |  eCos & RedBoot experts
gthomas@ecoscentric.com      |
http://www.ecoscentric.com/  |
------------------------------------------------------------


-- 
Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
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