As I mentioned before: receiving on the internet would be quite difficult to
do in a PIC, but sending should be relatively easy. Collision detect should
be rather simple, IMHO.

The idea here is not to substitute a PIC for a NIC (hey  - that's almost
poetic :-)), but rather to eliminate the NIC entirely, using the
one-and-only pic in the system to directly drive the ethernet.

Bob Ammerman
RAm Systems
(high performance, high function, low-level code)

----- Original Message -----
From: Scott Dattalo <scott@DATTALO.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Saturday, June 17, 2000 9:33 AM
Subject: Re: [PIC]: Taking it to an extreme


> On Fri, 16 Jun 2000, Bob Ammerman wrote:
>
> > I have been deeply involved in the thread about the 'open source emWare
like
> > project'  (in fact I started it :-), but I have been thinking about
another
> > end of the spectrum (I've noticed most spectra end up with many more
than
> > two ends :-).
> >
> > A 10Mb/second ethernet signal could be directly generated by a PIC. I am
> > currently generating video at that rate using the USART of a PIC18C452.
> >
> > What I am thinking is that an application could build a complete
ethernet
> > packet (containing, if desired a UDP datagram embedded in an IP frame)
in
> > RAM. This packet would include the complete ethernet preamble, packet
body
> > and CRC.
> >
> > The packet could then be sent _without the use of a conventional NIC
chip_
> > onto an Ethernet.
>
> I've been closely following this thread with great interest. However, this
stuff
> is outside my area of expertise. If you do take this approach, wouldn't
require
> the PIC to continuously monitor the ethernet traffic and
accepting/rejecting
> messages? This is probably the biggest benifit of the MAC. The second
biggest is
> the 8 or 16k of ram buffer that they provide. The third is the CSMA/CD
support.
> For cost sensitive applications, I could see sacrificing one PIC to bit
bang
> ethernet. But quite honestly, I don't think it's possible. Perhaps an SX
chip...
>
> Anybody got an idea how much some of these 10baseT ethernet controllers
> cost? The CS8900 is in the $10-$15 range as I understand. What about the
> RTL8019? What other chips could be used? The AMD, Intel, Infineon, etc.
chips
> are geared toward PCI busses and 10/100 controllers.
>
> Scott