Hi,
Daniel Schouten wrote:

>Hi all,
>I would like to add an ethernet interface to my PIC project for
connecting
>multiple units on one network and for future monitoring via the
internet. I
>was thinking of building an external interface box containing an
Ethernet
>chipset and a PIC to do the communication between the Ethernet chip and
my
>PIC project. How difficult is this to build, and what are exactly the
tasks
>performed by this Ethernet chip (TCP/IP handling?). Of course I need to
>assign and store an IP number too.
>
>I am looking for pointers about Ethernet hardware and protocol issues
(IP).
>
>Thanks a lot!
>
>Daniel...

Well as other has posted there are several options that will approach
the same goal,
however as this *is* the piclist and we all love pic's :) I would
propose the following:

As microchip has developed an *free* fully functional tcp/ip stack
available for download
at their site ( or will be in short time ) for the 18x series chip (I
belive). Why not
make an module with Pic+tansivier+PHY that uses an serial i/f to talk to
your unit.=20
( In principle an intelligent serial to ethernet gateway ). Now, how to
expose you data
through the IP i/f is probably application dependant and most likely
cannot be an general solution.
I'm planning (hoping?) to follow this route if time permitts in the
future.
( See Microchip demo board NET )

The main drawback with microchips stack is that it's done entirely in c
for 'portability'
reasons, I'm still in the dark ages coding entirely in asm so that will
hinder me.

But apart from that I see no big disadvantages in this solution.

It will enable 'old' units using serial i/f to be 'ethernet enabled', it
will only
add costs (an module) to units that actually requires the ethernet i/f.=20

Regarding protocols, I will most definately use UDP, although there are
drawbacks,
it's much more lightweight and contains less overhead(well sortof). It's
also eaiser
to perform broadcasts (one to many) and similar tasks.

I've already done similar stuff with pc's, s/w on one pc maps an
serialport to an TCP or UDP
port. Another pc has s/w to map an remote TCP or UDP port to simulate an
local serial port.
In this senario the application on the latter pc knows nothing about
networks or ethernet, it operates
as the remote unit is connected on the local serial port.

With this basic framework it's easy to go further and add web support
etc.=20

/Tony

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