Moin! On Fri, 16 Mar 2012 07:09:05 +0000 "Poul-Henning Kamp" <p...@phk.freebsd.dk> wrote:
> In message <20120315234624.a2da94430a247d235ca68...@kinali.ch>, 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 _______________________________________________ time-nuts mailing list -- firstname.lastname@example.org To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.