From owner-freebsd-hackers Tue May 14 21:18:49 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id VAA14022 for hackers-outgoing; Tue, 14 May 1996 21:18:49 -0700 (PDT) Received: from time.cdrom.com (time.cdrom.com [204.216.27.226]) by freefall.freebsd.org (8.7.3/8.7.3) with ESMTP id VAA14017 for ; Tue, 14 May 1996 21:18:47 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by time.cdrom.com (8.7.5/8.6.9) with SMTP id VAA03074 for ; Tue, 14 May 1996 21:17:51 -0700 (PDT) Prev-Resent: Tue, 14 May 1996 21:17:50 -0700 Prev-Resent: "hackers@freebsd.org " Received: from freefall.freebsd.org (jkh-sl0-f.cdrom.com [204.216.27.193]) by time.cdrom.com (8.7.5/8.6.9) with ESMTP id MAA02005 for ; Tue, 14 May 1996 12:02:24 -0700 (PDT) Received: from gaia.swip.net (gaia.swip.net [193.12.122.17]) by freefall.freebsd.org (8.7.3/8.7.3) with ESMTP id MAA03257 for ; Tue, 14 May 1996 12:01:55 -0700 (PDT) Received: from dialup105-3-3.swipnet.se (dialup105-3-3.swipnet.se [130.244.105.43]) by gaia.swip.net (8.7.5/8.7.3) with SMTP id VAA17937 for ; Tue, 14 May 1996 21:01:51 +0200 (MET DST) Received: by dialup105-3-3.swipnet.se with Microsoft Mail id <01BB41D8.FF393060@dialup105-3-3.swipnet.se>; Tue, 14 May 1996 21:04:53 +-200 Message-ID: <01BB41D8.FF393060@dialup105-3-3.swipnet.se> From: H Nalen To: "'www@freebsd.org'" Subject: Hello, Date: Tue, 14 May 1996 21:04:21 +-200 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Resent-To: hackers@freebsd.org Resent-Date: Tue, 14 May 1996 21:17:51 -0700 Resent-Message-ID: <3072.832133871@time.cdrom.com> Resent-From: "Jordan K. Hubbard" Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk Hi, I've needed help about DMA and searched the Web and found a good article = at your site.=20 I'm working with electronics and I have a app. that is rather = time-critical (if you know what I mean). I have a fast AD that need to = be served at a high rate, i.e store the data in realtime. I belive the = only way is to do it with DMA. I've using Intels 386-EX as CPU = (embedded) that has 2 DMA-channels. The AD need to store a 16 bits = parallell data at a rate of 5 us (up to 8 Mb). =20 What operating mode do YOU suggest? Single, chained? Do you think the = CPU and the other software "feels" this DMA-transfer?=20 One more question, the DRAM-refresh. Do it need much bustime? The DRAM = need refresh every 16ms and I wounder how much bus-time the refresh = takes? (Would the DMA-transfer been destroyed or delayed so the data = could not be saved correct?) I would be grateful if anyone could answer this few questions. If you = can't, can you tell me someone that can help me with this? regards' H Nal=E9n, SWEDEN__________________________________ Haekan Nalen, Raettvik, Sweden e-mail: h.nalen@mbox300.swipnet.se