In message <20120315234624.a2da94430a247d235ca68...@kinali.ch>, Attila Kinali w
rites:

>How good would that DAC need to be?

Depends on the level of ambition ?

>> 1-4MB RAM
>
>over a 256kB RAM it's get pretty thin if you want to stay in the uC
>busines. Unless you want to use an ARM9 or better with external SDRAM
>and Flash. But those are mostly BGA (very few QFP chips out there) and
>they are assumed to run Linux or Windows CE on them... Support for bare
>metal stuff is pretty thin.

There is no problem running bare-metal on ARM9's, I've done it.

But heck, it would be even better if you could load an OS on it, and
still get your bits through.

>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.

>> 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.


-- 
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FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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