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From: Jai Dhar<jdhar@e...>
Date: Tue Apr 12 18:49:51 CEST 2005
Subject: [oc] Sony IRCS Core
Thanks for your tips Mark, I have replied below.

Quoting Mark McDougall <markm@v...>:

> Jai Dhar wrote:
>
> > These two
> > codes (7 bit and 8 bit) are currently parallel outputs.
>
> 15 bits of parallel output could be inconvenient to low-end micros (with
> 8-bit data bus). You'd have to decode 2 separate addresses or use two
> GPIO ports (micro-controller).
>
> You may wish to consider an 8-bit wide FIFO to store a couple of
> device/command pairs (serially) whilst the host is too busy to process
> and/or has a high interrupt latency. This could be useful if interfacing
> to a small micro that disables interrupts for a while when it's doing
> something else.
>

So providing CLK+Data may be better I take it?

> > - when valid data is received, raise an interrupt pin. - Data bus
> > (both cmd and dev. registers) are constantly updated - When user
> > wishes to strobe data, assert an ack signal that clears the
> > interrupt.
>
> Are you contemplating an edge or level interrupt signal? I suspect level
> is easier to implement (eg. tie to FIFO not empty). Don't know whether
> you want to bother considering (host) interrupt sharing issues?!?
>
> Without a FIFO simply reading the register (RD strobe) could clear the
> interrupt. With a FIFO you could use the FIFO empty to control the
> interrupt line. I'd also consider having an interrupt enable/disable as
> well.
>

Level sensitive interrupt, mostly for the reasons you mentioned. Point noted
about the int. en/dis.

> > Essentially, it is up to the user to respond as fast as they wish -
> > the data will constantly be updated even if the interrupt isn't
> > serviced.
>
> Depends on whether or not a missed command is important. Using a FIFO
> could cause a lot less headaches for low-end host processors...
>

i'm thinking with remote controls, the last button press is most important. This
will be highly individual however. Thanks for the hints!

> Regards,
>
> --
> Mark McDougall, Software Engineer
> Virtual Logic Pty Ltd, <http://www.vl.com.au>
> 21-25 King St, Rockdale, 2216
> Ph: +612-9599-3255 Fax: +612-9599-3266
>




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