Lpc2000

Ok, since 2 people asked...

> That vendor and other vendors please! What ARM chips are out there
> with I2S bus?

It's Atmel.  These "SAM" parts have come up in this group over and over 
again.  Except for a few folks with early ES silicon, there's been a lot 
more hype and vapor than samples!

The 64k flash part is sampling now, but not in production yet.  
Production _might_ be in April, maybe.  Whatever they promise, remember 
they've been very late many times before (anyone remember waiting 2 
years for the AVR?)

http://www.atmel.com/dyn/products/product_card.asp?part_id=3521

If you click on the eval kit link, then click on "Avent" at the bottom, 
maybe it'll take you to a page with more info.  At least it did when I 
tried it a couple days ago, but this morning Avent's website only gives 
an error message.  Probably best to just call your local Avent office.  
They had about 30 of the eval boards in stock earlier this week.  Don't 
forget the part number: AT91SAM7S64-IAR.  It's $258 for pretty much just 
a board with the chip and IAR's USB-JTAG cable.

I can confirm this thing is finally for real.  I called up Avent about a 
week ago, and one of the eval boards is sitting right here.  Ordered 
with my personal credit card.  Didn't need to be a special/important 
customer to get it.  Just showed up yesterday.  Haven't hooked it up yet....

Also, I believe the Cirrus ARM parts have included I2S interfaces for 
years, but I'm not really familiar with those parts.  Years ago, they 
required external DRAM.

About the Atmel "SAM" parts, there's a lot of pretty impressive stuff.  
Lots of nice peripherals.  But one thing to pay attention to is the 
flash speed.  This opinion is only from reading the datasheet and not 
real experience with the part (yet), but it appears you can only really 
execute thumb from the flash at the full clock speed.  Also, if you use 
the USB port, you have to clock at 48 MHz (using the PLL, so at least a 
normal crystal is still ok).


The eval kit comes with some examples, but not really any app notes or 
other easy-to-understand docs yet.  If you're good at figuring out how 
to use peripherals from only datasheets, you're probably fine.  But if 
not, you may find much of the datasheet terse and difficult.  For 
example, try reading the USB section!  The I2S output is part of a 
pretty generic high-speed serial peripheral that's very configurable.  
So far, there's only minimal explaination and diagrams that show what 
each option really does.  Atmel does have an app note about I2S using 
what looks like an earlier version of this peripheral in one of their 
other chips, but this new one appears to have expanded some of the 
options.  My point is, at this early stage, be mentally prepared to need 
to do some fiddling and experimenting to figure out exactly how to 
really make this complex chip work the way you want.

But it finally is sampling and eval boards are available off the shelf 
to anyone (well, probably in the US only).  It does have I2S, and 
there's DMA-like buffering that makes these higher speed transfers 
reasonable without burning lots of CPU or needing really low interrupt 
latency.


Paul