Date: Tue, 14 May 1996 21:04:21 +-200 From: H Nalen <h.nalen@mbox300.swipnet.se> To: "'www@freebsd.org'" <www@freebsd.org> Subject: Hello, Message-ID: <01BB41D8.FF393060@dialup105-3-3.swipnet.se> Resent-Message-ID: <3072.832133871@time.cdrom.com>
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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
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