Re: FPGA for PCI based servo control board

[Robin Szemeti <robin-at-redpoint.org.uk>]

On Saturday 05 April 2003 22:49, John Kasunich wrote:

> >ethernet will be no worse than anything else here.
> >probably quite a bit better than most.
>
> It's better than the parallel port.  With ethernet, you
> either get good data, or no data.  With the parallel port,
> you can get bad data.

Really? .. coo. thats handy. I'll take out all these error checks and 
bad-packet counters in the core ethernet routines then ...

Ethernet is likely to be more susceptible to transient errors than parralel, 
because of lower peak-peak voltages, and higher clock speeds (using paralell 
8 bits wide you can use nice slow filters and take your time examining the 
line state to determine whether its high or low, with ethernet running at 
10mbs down a twisted pair, short duration interference of the (1us sort of 
duration) obliterates a whole bit, destroying an entire packet.) Slower, 
wider interfaces are always less likely to suffer data loss than fast thin 
ones, given similar transmission conditions.

Having said that, ethernet does seem to be quite robust, the differential 
nature of the signals helps a lot here.

-- 
Robin Szemeti

Redpoint Consulting Limited
Real Solutions For A Virtual World