In message <003101c46f76$1e5e3110$0300a8c0@billnye> Jamie Morken writes:
>----- 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)?
.....
>> 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.
For quite a few applications that is more than enough. The only times I
make sure I put embedded projects with extra RAM is where I have video
processing (dual ported) in one case an external Flash and SRAM for
some high speed image processing functions.
> I don't
>think this is enough sdram for most people but it is tempting to avoid the
>external ram and flash
Depending on code complexity the Flash may be small, but some networking
or the USB data buffering may eat up RAM.
>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!
Does look good in that respect, having used various micros with several
built in peripherals.
> 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.
Not the worst of sizes, and that pin pitch is quite large for [T]QFP devices
I have an Eagle CAD library available on
http://www.gnuh8.org.uk/ that has
Renesas chips where pin pitch of 0.5mm and even 0.4mm pitch is quite common.
I have built prototypes by hand with JBC iron and 0.2mm or 0.4mm tip size
using some of these chips.
> 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.
However if you have an Eagle library make it available to the download
section of Cadsoft website. If I have time I may be able to help out in
some ways if there is a Protel/Eagle exchange method. Not looked for one
yet. Artwork could always be reviewed to check dimensions etc. by others
in Gerber formats.
When you say microvias, I wonder what size you mean, having done some
boards with 0.2mm drill vias. Blind vias might be a different matter.
Some of the easiest method for PCB prototyping I use is people like
Beta Layout (
www.pcbpool.com) as I can send the Eagle (also Protel and
other files) and do some large number of layers as well. Not checked
capabilities on blind vias and min via size recently.
--
Paul Carpenter | paul@pcserv.demon.co.uk
<http://www.pcserv.demon.co.uk/> Main Site
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