On Fri, 16 Mar 2012 07:09:05 +0000
"Poul-Henning Kamp" <> wrote:

> In message <>, Attila Kinali 
> writes:

> >On the other hand, if you dont have to support an OS and work on the
> >bare metal, you can get away with very little RAM. 128k is a damn lot
> >if you have to fill it with usefull data structures ;-)
> Well, if you want to do full-FRI averaging for a loran-chain, you need
> something like 99600*2 * 4 = 800Kb.  If you want to do the full-hour
> averaging the WWVB doc talks about or DCF77 full-second phase-code,
> you need 2 MB for just the buffer.

Hmm... do you mean you want to store all samples of an hour and then
avarage over it? I think it would be better to just store phase offset
points for every second and then avarage over this. That would require
much less storage.

> >> USB2 interface 
> >
> >Which would mean you need a pretty recent chip as HighSpeed USB has not
> >been introduced into the uC world for more than 2 years or so.
> USB2, not USB3.

I'm not talking about SuperSpeed. USB2 support has been around for
quite some time in ARM7 class uC. But USB2 does not mean you support
a certain speed, just the data structures follow the revised standard.
Yes, USB2 introduced the HighSpeed mode (the 480Mbit/s), but below
ARM9/MIPS class CPUs it wasn't supported until about 2-3 years ago.
AFAIK the Atmel SAM3U was one of the first Cortex-M3 with HighSpeed
support available in volumes... and that was IIRC late 2009, early 2010.

And the number of uC's with HighSpeed support isn't that large yet.

                        Attila Kinali

The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
                -- Tirin, The Dispossessed, U. Le Guin

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