Isaac Marino Bavaresco wrote:
> 1) Micro-controllers with embedded 10/100 Ethernet controllers
> implement only the MAC, you will need an external PHY.

But there are some that implement MAC and PHY at 10Mbit/second, which is
already way more than small embedded applications can handle.  A good
example is the 18F67J60.  Support for 100Mbit/s in a small micro is just for
marketing reasons.  Nowadays ethernet switches automatically do 10 or 100
per port, so there is no downside to the network in having 10Mbit/s devices
connected.

Or put another way, push the complexity to the ethernet switch at no
incremental cost since it already has this capability.  Keep the cost of
your small embedded device down by using 10Mbit/s ethernet and let the
switch do the conversion for free.  100Mbit/s I/O to a small micro is just
silly.  Even accounting for some overhead, what are you going to do with a
byte every 100nS?  Even a byte every 1uS is more than a small micro can
sustain if it's doing anything else, like running a TCP stack.


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