Re: [Balloon] Balloon3 - PXA version

----- Original Message -----
From: "Steve Wiseman" <steve@steves-house.org.uk>
To: <balloon@balloonboard.org>
Sent: Wednesday, July 21, 2004 2:54 AM
Subject: Re: [Balloon] Balloon3 - PXA version


> 19/07/2004 15:01:53, "David Bisset"
> <david_bisset@itechnic.co.uk> wrote:
>
> >Steve,
> >Can we know what's currently on the PXA version, or in your
> head...
> >(delta from 2.05/2.06)?
>
> Well, 2 days ago, the plan was a simple spin, adding a PXA255
> and a kinder-to-software USB controller, plus rolling in any
> bugfixes that were called for. However, Nick has put unclean
> thoughts in my mind about PXA27X, and I'm very, very tempted.
> It's 2 generations on, and it shows - I could ditch the external USB
> controller and boot ROM, but I'd have to abandon the current
> cheap&cheerful SDRAM and move to something low voltage - good
> in some ways, annoying in others.
> Some of the other PXA27X peripherals are pretty spiffy, too.
> (Particularly taken by the MSL to avoid the need for shifting huge
> busses around, and teh DMA controller now seems to be rather
> more capable. The AC97 codec interface has a certain simple
> charm - dunno if AC97 codecs come in low-power versions yet -
> the last one I played with was a current hog)
>
> Factors counting against the PXA27X are:
> Software - the power control is pretty serious, and I know that the
> SA1110 code doesn't always kick down as far as I'd like, and teh
> peripherals are many and varied. There'll be fun beating the bugs
> out of this. I'm not tracking the handhelds porting progress, on
> whose shoulder
> It's a big change. SA1110 to PXA255 was trivial(ish). The PXA27X
> is, while still a SA1100 at heart, a substantial spin. The reference
> schematic is 100 sheets, implying that I've got a heck of a lot of
> reading. In fact, all the datasheets are massive.
>
> At the moment, I'm tending towards the 27X, any comments from
> the list?

I think the PXA27x series is great too :) The only problem I have heard
about it is that
it may be a short production run and thus may not be available for very
long, this is because
it is made not for the broad market but for just PDA's (this is what my
local Intel rep has told
me). I like the PXA271 the best as it has 32MB sdram and 32MB flash built
in to it. I don't
think this is enough sdram for most people but it is tempting to avoid the
external ram and flash
interfaces and make a simple board with just the power and JTAG routed and
SPI/I2C and
have a high performance 32bit controller for embedded projects like
robotics! I have made an
eagle cad library package for the pxa271/2/3 (pxa270 has a different
package), and the pin pitch
is really quite small (0.65mm) whereas the pxa255 has 1.0mm pitch. So this
could make it harder
to route and may require a more expensive PCB with microvias. I am
interested in helping out
(if you are accepting volunteers!) whether you choose a PXA255 or PXA27x for
your next board.

best regards,
Jamie Morken



>
> Steve
>
>
>
>
>
>
>
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