From owner-freebsd-hackers Mon Apr 28 17:35:11 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.5/8.8.5) id RAA11243 for hackers-outgoing; Mon, 28 Apr 1997 17:35:11 -0700 (PDT) Received: from neophyte.dweeb.net (dialup-07.cc.strath.ac.uk [130.159.96.149]) by hub.freebsd.org (8.8.5/8.8.5) with ESMTP id RAA11238 for ; Mon, 28 Apr 1997 17:35:01 -0700 (PDT) Received: from neophyte.dweeb.net (localhost.dweeb.net [127.0.0.1]) by neophyte.dweeb.net (8.8.5/8.8.5) with ESMTP id BAA00916; Tue, 29 Apr 1997 01:32:54 +0100 (BST) Message-Id: <199704290032.BAA00916@neophyte.dweeb.net> To: freebsd-hackers@freebsd.org cc: nbc@neophyte.dweeb.net From: nbc@vulture.dmem.strath.ac.uk Subject: FreeBSD As Motor Controller? Date: Tue, 29 Apr 1997 01:32:53 +0100 Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk Dear all, I am currently in the process of implementing an embedded motor control system using a well know real-time UNIX, which has turned out to be slightly overkill. The system is soft real-time, which made me wonder if FreeBSD would be up to the job - I envisage a stripped down system, running on PC/104 hardware (already tested with F/BSD), the drivers residing at device level, preferably in LKM format. At the moment we are using stepper motors, although this may change in the future, driven by pulses generated from an I/O board on the ISA bus. My major concern with FreeBSD is interrupt latency, which is excellent with the current system. Given that we are using 100MHz Cyrix 586 CPUs, I'd appreciate it if anyone could give me a ballpark figure on the latency, and indeed the typical variations in such one would expect from a lightly loaded system, or perhaps some way to determine this for myself. I've read the device driver writer's guide on the Freebsd www site, which claimed it was for those familiar with the standard UNIX device driver model, which I am not; as a final favour, could anyone recommend a decent book or two for those intending to learn? My only recollection of such literature is an old Sun/3 manual, read many, many years ago :-) Thanks in advance for all your help, please do not hesitate to ask if any further information is required. -------- Neil Clark Transparent Telepresence Group http://telepresence.dmem.strath.ac.uk/nbc