On Wed, Sep 15, 2004 at 10:44:52AM +0100, SHands wrote:
> Has anyone had any experience in connecting PIC's to RJ45-based networks
> at all? Basically, I'm after getting a very basic telnet server running
> to control outputs that'll be in either the on/off state. 

A couple of suggestions:

1) Separate protocol from media. One of the first things you'll figure out
is that you don't need a telnet server for On/Off state. UDP is much
better suited for that task and more importantly is much much simpler
to implement.

2) If you're going to have a lot of these then you may want to consider
having a router that changes media. For example it would be real simple
to implement SLIP on a RS485 network, then have a single ethernet to
RS485 router to route packets to that network.

> 
> I've done a quick search on the net - but can only turn up ready-made
> boards with RTL8xxx chips and pre-programmed PIC's, (which isn't much
> fun - and can't really learn anything).

I think that E Cheung had the best appoach. He devised a PIC based system
that talked to ISA ethernet cards. So instead of having to worry about
wiring up a chip, the PIC implement an ISA slot that the card plugged
into. You can find the design entry here:

http://www.edcheung.com/awards/pic2k/c0700cw2.htm

On the protocol side he implement a simple web server. But again I believe
that UDP is the right package format for sch simple data. It does mean that
either the client will have to have some software to receive and display
the incoming packets, or more likely that there will need to be a server that
will collate the incoming information and present a web interface.

BAJ
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