From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM autolearn=unavailable autolearn_force=no version=3.4.4 X-Received: by 10.43.144.81 with SMTP id jp17mr4128521icc.25.1424885726887; Wed, 25 Feb 2015 09:35:26 -0800 (PST) X-Received: by 10.140.101.148 with SMTP id u20mr61721qge.5.1424885726857; Wed, 25 Feb 2015 09:35:26 -0800 (PST) Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!mx02.eternal-september.org!feeder.eternal-september.org!news.glorb.com!peer03.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!hl2no30092943igb.0!news-out.google.com!c1ni194qar.1!nntp.google.com!i13no7487847qae.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: comp.lang.ada Date: Wed, 25 Feb 2015 09:35:26 -0800 (PST) In-Reply-To: Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=105.236.75.241; posting-account=orbgeAkAAADzWCTlruxuX_Ts4lIq8C5J NNTP-Posting-Host: 105.236.75.241 References: <8e30f54c-81c4-4861-897c-bb6c563c76e8@googlegroups.com> User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: Subject: Re: silly ravenscar question From: jan.de.kruyf@gmail.com Injection-Date: Wed, 25 Feb 2015 17:35:26 +0000 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Received-Bytes: 3213 X-Received-Body-CRC: 1121167247 Xref: news.eternal-september.org comp.lang.ada:25037 Date: 2015-02-25T09:35:26-08:00 List-Id: On Wednesday, February 25, 2015 at 12:45:53 PM UTC+2, Dmitry A. Kazakov wro= te: > The high end is 8 analogue channels 100=E7=9B=9C over the network + hundr= eds of > lower speed channels. Data volumes is not a big problem. E.g. we can samp= le > 8 100=E7=9B=9C channels and distribute them over the network without data= loss, > doing 10ms oversampling. >=20 What is '100=E7=9B=9C ' ? '0xc79b9c' was nowhere to be found. what do you mean to say by 10msec oversampling? Average in the terminal and= send only every 10 ms? in any case to focus the thinking, I did some quick sums: A packet with a payload of 50 bytes, according to the theory should be able= to do the roundtrip (100 m cable, 1 switchbox, no packet contention) in 25= usecs through an stm34 board, with time to spare. that includes DMA and of= floading and onloading of data. So that makes 40 packets per msec. Leave some space for syncframes, arp fra= mes and data loss, then 20 roundtrip packets /msec should be doable, provid= ed the jitter is strictly controlled.=20 An individual terminal has all the time in the world to handle the data bet= ween commframes, but I bet that, depending on what you want out of the syst= em, the pc might feel the strain at that rate. (and the rt scheme must be u= p to scratch in the pc) So the bottleneck according to me is in the pc in most cases. In any case so according to your specs we would need some kind of multiplex= ing scheme. I did not need that, the project is too small; but it is good i= n this case to do a little bit of thinking up front, before too much code i= s written. =20 > . . . which may be not an issue for single-core > board with non-preemptive scheduling. Thats how we did it before Noahs flood, and boy did it run fast. cheers, j. =20