Embedded Internet

On Tue, 24 Feb 2004 23:10:25 +0000, Max wrote:

> But even using a true microcontroller, the overhead of the RTL8019AS
> isn't all that great, since you don't actually need most of the
> address lines, and they can just be pulled. An example is Microchip's
> POC board for 10-baseT, which uses only five address lines, or 15 I/Os
> in total - reasonable on a 40-pin chip with 33 I/Os:
> http://www.microchip.com/download/tools/picmicro/demo/pdemnet/39563b.pdf

	Maybe it depends on what the definition of "is" is.  15 i/o pins on a
microcontroller eats quite a bit of cpu resources when most of those pins
have to be bit-banged plus a lot of embedded micros require quite a few of
those I/O pins when external memory is needed which would eliminate its
use for an embedded controller/server.

>>I prefer to design for the future, not the past.
> 
> You're never required to deliver real working systems today, then?
> Nice job.

	Sarcasm is not a good way to have dialog, smartass.
 
-- Regards, Albert
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AM Research, Inc.    			  The Embedded Systems Experts
http://www.amresearch.com          			  916.780.7623
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On Tue, 24 Feb 2004 22:07:21 -0800, Albert Lee Mitchell wrote:

>	Maybe it depends on what the definition of "is" is.  15 i/o pins on a
>microcontroller eats quite a bit of cpu resources when most of those pins
>have to be bit-banged

Sorry, that's just not true. The demo board I mentioned is quite
capable of running a simple web server with only a cheap PIC16F877
@5MIPS, doing HTTP, TCP, UDP, ICMP, IP, ARP etc. in addition to
driving the Realtek chip. If you need more horsepower for your APP,
swap it for a PIC18 @10MIPS, or re-design with whatever MPU you fancy.

>plus a lot of embedded micros require quite a few of
>those I/O pins when external memory is needed which would eliminate its
>use for an embedded controller/server.

If external memory is being used, then you'd presumably memory-map the
PHY, as Gerard suggested, which results in zero overhead on I/O pins
(or one pin for CE if you're not externally decoding address spaces).

>>>I prefer to design for the future, not the past.
>> 
>> You're never required to deliver real working systems today, then?
>> Nice job.
>
>	Sarcasm is not a good way to have dialog, smartass.

Well, what sort of response do you expect to that sort of meaningless
pomposity? I fail to see what is wrong with hanging a Realtek PHY on a
cheap MCU to achieve 10-baseT connectivity, given that it meets the
requirements of the project in hand. You seem to be suggesting that
all projects should be over-engineered to allow for some nebulous
degree of future expansion, irrespective of whether the client
requires it or not (and, presumably, irrespective of cost). Frankly, I
think that's an untenable position to take.

-- 
  Max