> Rich Ottosen and I have discussed this from time to time.  Even running the
> PIC at the maximum rated speed, the amount of external hardware needed to
> provide hardware assist for Ethernet will cost more than a complete
> Ethernet chip.  The receive side is the more difficult, and requires a PLL
> for clock recovery and a Manchester decoder, in addition to a shift register.
> The bit stuffing could potentially be done in software.
>
> A simple Ethernet chip like the Crystal Semiconductor CS8900 is very
> inexpensive and does not require many other components.  It has enough
> internal memory for two Ethernet frames, and the host interface is simple.
> It should be possible to use this with a PIC to implement a simple network
> node.
>
> Even with the Scenix part in turbo mode at 50 MHz (20 nS per instruction),
> Ethernet would still require substantial external support hardware if a
> standard Ethernet chip was not used.
>
> SMC also makes a simple Ethernet chip like the CS8900, but I don't know the
> part number.

Another option could be to use CAN (Controller Area Network) instead
of Ethernet.

Richard Rosenheim
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