Schematic preferences
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From: Joel Koltner on 21 Jan 2010 20:17 "krw" <krw(a)att.bizzzzzzzzzzz> wrote in message news:ibthl55mps3jo3c61v9kmg1189cbse7o63(a)4ax.com... > It's a special case, one that likely wouldn't be used enough for it to > be obvious. No thanks. Fair argument, but the whole "let's use hierarchical" idea that you and I both support is often dismissed for the same reason ("won't be used enough for it to be obvious,"), don't you think? (Particular in companies that are usually doing small designs that could fit on just a few, say, C-sized sheets.)
From: krw on 21 Jan 2010 20:22 On Thu, 21 Jan 2010 17:17:29 -0800, "Joel Koltner" <zapwireDASHgroups(a)yahoo.com> wrote: >"krw" <krw(a)att.bizzzzzzzzzzz> wrote in message >news:ibthl55mps3jo3c61v9kmg1189cbse7o63(a)4ax.com... >> It's a special case, one that likely wouldn't be used enough for it to >> be obvious. No thanks. > >Fair argument, but the whole "let's use hierarchical" idea that you and I both >support is often dismissed for the same reason ("won't be used enough for it >to be obvious,"), don't you think? (Particular in companies that are usually >doing small designs that could fit on just a few, say, C-sized sheets.) Not true at all. If it worked, every design I did would be hierarchical. All of my FPGA designs are hierarchical. ;-)
From: Joel Koltner on 21 Jan 2010 20:33 "krw" <krw(a)att.bizzzzzzzzzzz> wrote in message news:4cvhl51aubv1lm3bjg0vats3ksk7prdgma(a)4ax.com... > Not true at all. If it worked, every design I did would be > hierarchical. All of my FPGA designs are hierarchical. ;-) Right, what I meant is that *other people* who weren't used to hierarchical designs before would be telling you as much. But anyway, I accept that you don't find the C[1:20] syntax helpful/problem-proof enough to be useful.... I have, though. :-) ---Joel
From: John Fields on 21 Jan 2010 20:33 On Thu, 21 Jan 2010 18:46:32 -0600, krw <krw(a)att.bizzzzzzzzzzz> wrote: >On Thu, 21 Jan 2010 11:59:21 -0600, John Fields ><jfields(a)austininstruments.com> wrote: > >>On Wed, 20 Jan 2010 17:33:28 -0700, D Yuniskis >><not.going.to.be(a)seen.com> wrote: >> >> >> >>>Exactly! Read my original comment: >>> >>>"E.g., RUN and STOP instead of RUN and RUNN (or NRUN)." >>> >>>Obviously, this refers to *two* signals. One of those is the >>>complement of the other (RUN -> RUNn, RUN -> STOP). The point I >>>was making is that I will *avoid* the "_n" in favor of choosing a >>>signal name that inherently implies the negation of its counterpart. >>>YES -> NO. RUN -> STOP. LEFT -> RIGHT. >>> >>>This avoids the "negation" issue for the most part (i.e., always >>>name "negative" signals with their antonyms) >> >>--- >>I don't understand what you're saying, but what works for me is to name >>the signal appropriately and then to assign it the polarity which >>results in the desired action being asserted. >> >>For example: (View in Courier) >> >>If have a signal which goes high and I want to use that signal to >>trigger an RS latch which will, say, start a motor, then I'll call the >>signal START and I'll wire it into a pair of positive true NORs like >>this: >> >> >>START>----A _ >> NOR Y--+ >> +--B | >> | | >> | _ A >> +-----Y NOR >> B >> >>Let's also say that the signal required by the controller, which will >>turn the motor on, is a momentary low-going signal. Then the signal >>chain would look like this: >> >> CONTROLLER >> +--------------+ >>START>----A _ _____ |_____ ___| >> NOR Y--+-->START>---O|START ON/OFF|--[MOTOR] >> +--B | | | >> | | | | >> | _ A >> +-----Y NOR >> B > _____ >Except that START and START are not complementary. In this case >_____ _______ _____________ >START should be something like RUNNING or START_LATCHED >or some such. --- Yes. Nice one! :-) --- >> >>To finish it up, let's say the either the controller or the user can >>turn the motor off, and that either must generate a momentary low to do >>that, with both signals staying high the rest of the time. >> >>Then we have: >> >> CONTROLLER >> +--------------+ >>START>----A _ _____ |__ ___| >> OR Y-----+-->START>---O|ST ON/OFF|--[MOTOR] >> +--B U1 | | | >> | | ____ |__ ____| >> +-----------|-->STOP-----O|SP STOP|O--+ >> | | | | | >> | _ A--+ _ +--------------+ | >> +-----Y OR A----------------------------+ >> U2 B---Y _ OR >> U3 B--+ >>____ | >>STOP>---------------------+ >> >>Notice that all of the gates are functionally ORs but, because of the >>annotation being applied to indicate function, in the real world U1 and >>U2 would be something like HC02 NORs, and U3 (being its De Morgan >>equivalent)something like an HC00 NAND. > >YES! Thank you! --- My pleasure. :-) ____ Just to clean things up, your critique about START also applies to STOP from the user side, so this annotation would probably make everything clearer: >> CONTROLLER >> +--------------+ >>START>----A _ ____ |____ ___| >> OR Y-----+-->STIN>----O|STIN ON/OFF|--[MOTOR] >> +--B U1 | | | >> | | ____ |____ _____| >> +-----------|-->SPIN>----O|SPIN STOUT|O--+ >> | | | | | >> | _ A--+ _ _____ +--------------+ | >> +-----Y OR A--<STOUT<-------------------+ >> U2 B---Y _ OR >> U3 B--+ >>____ | >>STOP>---------------------+ JF
From: John Fields on 21 Jan 2010 20:48
On Tue, 19 Jan 2010 08:32:48 -0800, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Tue, 19 Jan 2010 05:26:50 -0800 (PST), mpm <mpmillard(a)aol.com> >wrote: > >>On Jan 18, 3:37�pm, D Yuniskis <not.going.to...(a)seen.com> wrote: >>> Hi, >>> >>> Of course, this is *highly* subjective -- but, I'd enjoy hearing >>> folks' "conventions" used when preparing schematics (that *others* >>> will consume -- how you scribble for your own purposes isn't >>> important as it depends a lot on what *you* want out of the >>> drawing). >> >> >>My main rule (a preference actually) is that the same name be used in >>the callouts when a circuit involves several schematic sheets! >> >>I once worked for a video company that had a PLL circuit that >>traversed 6 or 7 different circuit boards. >>I guess each engineer / designer was responsible for his own board, >>because none of the names matched up. >>This made final device test & calibration very difficult. >> >>This device comprised roughly 75 "D-size" sheets of schematics. >>I can still smell the ammonia from the Diazit copier.. > >I still have and use a D-size diazo copier! --- My need for generating and disseminating drawings is modest, so I use my trusty old HP DesignJet 450C. JF |