From owner-freebsd-current Thu Jun 11 03:46:00 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id DAA14894 for freebsd-current-outgoing; Thu, 11 Jun 1998 03:46:00 -0700 (PDT) (envelope-from owner-freebsd-current@FreeBSD.ORG) Received: from labinfo.iet.unipi.it (labinfo.iet.unipi.it [131.114.9.5]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id DAA14809 for ; Thu, 11 Jun 1998 03:44:44 -0700 (PDT) (envelope-from luigi@labinfo.iet.unipi.it) Received: from localhost (luigi@localhost) by labinfo.iet.unipi.it (8.6.5/8.6.5) id JAA22102; Thu, 11 Jun 1998 09:45:30 +0200 From: Luigi Rizzo Message-Id: <199806110745.JAA22102@labinfo.iet.unipi.it> Subject: Re: floating point usage within the kernel - howto ? To: jb@cimlogic.com.au (John Birrell) Date: Thu, 11 Jun 1998 09:45:30 +0200 (MET DST) Cc: mike@smith.net.au, current@FreeBSD.ORG In-Reply-To: <199806110659.QAA18095@cimlogic.com.au> from "John Birrell" at Jun 11, 98 04:59:16 pm X-Mailer: ELM [version 2.4 PL23] Content-Type: text Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > Luigi Rizzo wrote: > > they want to run a P-I-D controller (and more generic controllers > > if this goes well) to control a few motors, for didactical purposes. > > What update rate do they need that requires the code to run in the kernel? whenever i ask this question the answer is invariably "as fast as possible". In any case, we don't have a real target application, it is just a framework that must be adapted to different apps, so i would expect a max rate of 1 KHz to cover all practical purposes, with 100Hz being sufficient in many cases. > If they want to program like DOS, that's what they should use. 8-) you see, apart from the network-accessibility problem, they are wasting a lot of resources using DOS, because they tend to write non-portable code in assembler and spend way too much time in building the user interface. I thought to propose them a different approach that could be more flexible. Once they learn to work under unix, and the controller and the UI are kept well separated by a kernel barrier, it is easier to reuse their software, and even replace the (software) controller with a real one. (and, last not least, robotics people tend to have a lot of money just because their hardware costs so much :) cheers luigi -----------------------------+-------------------------------------- Luigi Rizzo | Dip. di Ingegneria dell'Informazione email: luigi@iet.unipi.it | Universita' di Pisa tel: +39-50-568533 | via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 | http://www.iet.unipi.it/~luigi/ _____________________________|______________________________________ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message