[time-nuts] Form Factor and such, Big Picture

Javier Herrero jherrero at hvsistemas.es
Thu Dec 23 18:38:32 UTC 2010


El 23/12/2010 19:08, Chris Albertson escribió:
>
>
> There are some really great embedded processors out.  The problem is
> software.  If you pick some "exotic" processor then you will be the
> only one to write software for it.  To avoid that I'd pick one that
> "most" people already know. The bottleneck in these projects is always
> software and you should design hardware to minimize that problem even
> if it adds $20 to the cost.
No need to pick an exotic one, and software is not a great bottleneck. 
If you write bare-metal applications, you can done all in C (I've done a 
lot with ARM and never wrote a line in assembler for it). Also, lots of 
free tools (for ARM, for AVR, etc.). If you use a processor running an 
embedded OS like uClinux, you have not to bother to write the low level 
software (the one that interacts directly with the h/w) except if you 
need to write a driver for some peripheral, and you get full networking 
support, solid state disk support and lots more. But you need more ROM 
and more RAM (quite a bit more).
>
>
>
> That said the basic counter project should NOT need such a powerful
> CPU.  A little 8-bit uP with 14 pins should be enough.
>
When you have a decent ARM for <$10, and a great ARM for <$20 with USB, 
100Mbps Ethernet including phy, CAN, I2C, SPI, SSI, lots of timers, 
etc... and a 32-bit core running at 50 or 80MHz, you tend to forget 
anything like an 8-bit PIC (I'm talking about one-off projects or small 
series - for large series, hardware cost is ever more important - and 
PICs are not unexpensive except for the very small ones, either. In the 
first cases, only one hour in software development that you can save 
using a more powerful processor rentabilizes it)

And for time nuts, the LM3S9B96 even has IEEE-1588 support ;) 
Development kits for the LM3S9B9x are in the order of $100 and looks 
very nice even for including 'as is' in a one-off project (not in a 
series - long term delivery is never guaranteed). Check Mouser (for 
example) for them.

Regards,

Javier


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Javier Herrero                            EMAIL: jherrero at hvsistemas.com
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