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RE: cyg_drv_interrupt_create ()
- To: "'Lewin A.R.W. Edwards'" <larwe at larwe dot com>
- Subject: RE: [ECOS] cyg_drv_interrupt_create ()
- From: "Trenton D. Adams" <tadams at extremeeng dot com>
- Date: Fri, 22 Jun 2001 09:13:27 -0600
- Cc: <ecos-discuss at sources dot redhat dot com>
- Organization: Extreme Engineering
Ok, thanks. I'll look into the eCos hal, and see what I can do.
> -----Original Message-----
> From: Lewin A.R.W. Edwards [mailto:larwe@larwe.com]
> Sent: Friday, June 22, 2001 9:06 AM
> To: Trenton D. Adams
> Cc: ecos-discuss@sources.redhat.com
> Subject: RE: [ECOS] cyg_drv_interrupt_create ()
>
>
>
> > > the remainder are routed to IRQ (CODEC, the three EINT pins, TC1
> > > underflow,
> >
> >So you're saying that there are acutally only one IRQ, and
> one FIQ, but
> >there are three EINT pins?
>
> Correct. The interrupt controller is conceptually a
> multi-input OR gate and
> a latch. When the CPU receives an interrupt from whatever source, the
> appropriate bit in the latch is set. The outputs of the latch
> are ORed
> together (all the FIQs are ORed to a single FIQ request line on the
> processor core, and all the IRQs are ORed to a single IRQ
> request line on
> the processor core). There is no vectoring performed by the
> processor. If
> you cause an nEINT3, all the CPU knows is that it got an IRQ. It's
> software's responsibility, in the IRQ ISR, to read the state
> of the latches
> (INTSR1/2/3) and determine who caused the interrupt.
>
> (The hardware implementation is more complicated than that,
> of course, but
> conceptually it works as above).
>
>
> -- Lewin A.R.W. Edwards
> Embedded Engineer, Digi-Frame Inc.
> Work: http://www.digi-frame.com/
> Tel (914) 937-4090 9am-6:30pm M-F ET
> Personal: http://www.larwe.com/ http://www.zws.com/
>
> "Far better it is to dare mighty things, to win glorious
> triumphs, even
> though checkered by failure, than to rank with those poor spirits who
> neither enjoy much nor suffer much, because they live in the
> gray twilight
> that knows not victory nor defeat."
> (Theodore Roosevelt)
>
>