Re: [uCsimm] 125 micro second latency - REALTIME?

From: Florian G. Pflug (
Date: Mon Apr 17 2000 - 05:03:33 EDT

On Sat, Apr 15, 2000 at 12:26:48AM -0500, Peter E. Thomas wrote:
> Hello All-
> I was wondering if the ucSimm is capable of sending data out the ethernet
> port every 125 microseconds. Will I need to use the real time patches?
> Has anyone tried to use the ucSimm hardware to send data at a regaular
> fast rate like that? This will be in a system that CAN NOT allow a data
> pack to be dropped. Any ideas?

I don't know wheter your uCsimm can handle this - but sending packets at a
rate of 10kHz ist quite fast.

However, you have to keep in Mind, that Ethernet itself it not an
deterministic network. This means that you don't actually _know_ wheter you
will be able to send every 125 uS. The Medium could be in use - and if there
is a collision at the first attempt to send a packet, then you have to wait
a _RANDOM_ time - but I don't know in which range this backoff-time lays.

greetings, Florian Pflug
This message resent by the list server

This archive was generated by hypermail 2b30 : Sun Apr 07 2002 - 00:01:35 EST