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: jherr...@hvsistemas.com
Chief Technology Officer
HV Sistemas S.L. PHONE: +34 949 336 806
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