Ping John Larkin: Question on MAX
in [Design]
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From: krw on 31 May 2010 21:20 On Mon, 31 May 2010 17:10:31 -0700, "Joel Koltner" <zapwireDASHgroups(a)yahoo.com> wrote: >Hi Keith, > ><krw(a)att.bizzzzzzzzzzzz> wrote in message >news:kcu406lla4kc1kp5vfn42cuubjfc6o32fv(a)4ax.com... >> Our "value" and "P/N" fields are separate so that only the value is printed >> on >> the schematic, not the entire P/N. > >Yeah, that's what we presently do as well... the part numbers are long enough >that you'd end up with rather cluttered schematics if they were always on, >although I suppose some places might have them on by default and then have the >guy drawing the schematic just turn them off for individual components in >areas that too become too dense. That would be everywhere. ;-) >> We *can* add parts, but leave it to the "component engineer", who also is >> the >> layout guy. I'll make OrCad symbols and put them in my own library. He >> pulls >> them from there and checks all the information before putting it in a >> "standard" library. > >We can't add (or modify) parts, but otherwise we do the same thing. There are only three of us likely to add components, but it's just cleaner if one does it. I don't like the way others draw components so I do my own, even if it already exists. >> He was likely given the position without the time or perhaps authority to do >> the job properly. Management is often does things like that. > >Yes, I'd accept that he had too many tasks to perform that were more company >business-critical than fixing parts libraries. However, I don't see any good >excuse for why he'd make that claim while simultaneously refusing to allow >some of the engineers to go and clean things up (and they had volunteered to >do so). Management eventually leaned on him, telling him he either had to >start fixing errors in a timely manner or allow other to do so in his stead, >and since he didn't like either of those options, he chose to quite instead. Sounds more like it was a power trip for him. You don't need control freaks around.
From: John Larkin on 31 May 2010 22:19 OK, I just finished (or at least got working) BLUE.EXE. It compares the parts in a PADS-Logic netlist to our MAX parts/inventory database. It checks that each PADS part on the board has the required attribute fields. A part entry in the PADS-Logic netlist file looks like PART C50 { "ORIG" JL 7-24-96 "DESC" 0603 SURFACE MOUNT CAPACITOR "HTI" 103-2720 "VALUE" 0.33uF } Where HTI is our in-house MAX stock number. Pretty ugly, no? PITA to parse. The program verifies that the DESC, HTI, and VALUE fields are present and look about right, then verifies that the corresponding MAX part actually exists, then verifies the value and package types against what MAX expects. I only process R/L/C parts, since they are the ones that cause the most trouble. It's done in PowerBasic in the clumsiest way possible... tons of string operations, linear search of all MAX parts for every PADS part, gross stuff like that. Analysis of a 1200 part VME board runs in 0.156 seconds. Parsing and comparing the values was a little tricky. 0.33uF was not exactly the same as 330nF in floating point, and some people decided that m was milli but M was mega. Sometimes. And things like "1206" can appear in various places in the DESC field for some PADS parts, like resistor networks. And so on. 560 line source file, 38 kbytes compiled. PINK.EXE was the one that compares two PADS-Logic or PADS-PCB netlists. John
From: Joel Koltner on 31 May 2010 22:46 "John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message news:atp806ddh0j8oqqql9n1ujvm3s1h21b2uc(a)4ax.com... > "DESC" 0603 SURFACE MOUNT CAPACITOR > > Where HTI is our in-house MAX stock number. Pretty ugly, no? PITA to > parse. Having the attribute names in quotes but the attribute values not in quotes sure is a pain... > Parsing and comparing the values was a little tricky. 0.33uF was not > exactly the same as 330nF in floating point I was wondering if you were going to deal with this... I've often felt a tool that goes around and "standardizes" all the decoupling caps to 100nF or 0.1uF or whatever one prefers would be useful. Not because I'm a nazi when it comes to suggesting that there should be hard rules for when fractional values are OK or not (although some people around here are...), but rather because I think there's value in having consistentcy in your schematic: 100nF vs. 0.1uF vs. 0u1 (ouch!) tends to just say something about how old you are (when you went to school) or if you're in the U.S. or Europe, but different styles throughout the schematic makes you look schizophrenic, which is rather more worrisome. > and some people decided > that m was milli but M was mega. Sometimes. I once had a "helpful" tech decide that my 22milliohm current-sensing shunt resistor (labeled "22m" on the schematic) was really 22megaohms. The circuit didn't really work after he made that substitution... :-) I take it your program elicits some warnings if it's trying to be "smart" and discoveres that m/M confusion likely exists? > 560 line source file, 38 kbytes compiled. Sounds pretty useful; very neat! For some real fun you should write up a description of the program and see how much a professional software developer would want to code it up. :-) ---Joel
From: John Larkin on 31 May 2010 23:04 On Mon, 31 May 2010 19:46:11 -0700, "Joel Koltner" <zapwireDASHgroups(a)yahoo.com> wrote: >"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message >news:atp806ddh0j8oqqql9n1ujvm3s1h21b2uc(a)4ax.com... >> "DESC" 0603 SURFACE MOUNT CAPACITOR >> >> Where HTI is our in-house MAX stock number. Pretty ugly, no? PITA to >> parse. > >Having the attribute names in quotes but the attribute values not in quotes >sure is a pain... > >> Parsing and comparing the values was a little tricky. 0.33uF was not >> exactly the same as 330nF in floating point > >I was wondering if you were going to deal with this... > >I've often felt a tool that goes around and "standardizes" all the decoupling >caps to 100nF or 0.1uF or whatever one prefers would be useful. Not because >I'm a nazi when it comes to suggesting that there should be hard rules for >when fractional values are OK or not (although some people around here >are...), but rather because I think there's value in having consistentcy in >your schematic: 100nF vs. 0.1uF vs. 0u1 (ouch!) tends to just say something >about how old you are (when you went to school) or if you're in the U.S. or >Europe, but different styles throughout the schematic makes you look >schizophrenic, which is rather more worrisome. Often schematics are assembled by cut-and-paste from other schematics. Then the bypasses do look schitzoid. I use 0.33uF 0603 as my standard bypass, but the kids have decreed that it should be "330nF" We do try to minimize the different parts on a board to simplify pulling kits and assembling boards. 100R, 1K, 10K, like that. It wouldn't be hard to pile up a *lot* of microfarads of bypass caps on one plane, scattered over many sheets of schematic. Enough to freak out some LDOs that, on the power supply page, have an aluminum or tantalum bypass. > >> and some people decided >> that m was milli but M was mega. Sometimes. > >I once had a "helpful" tech decide that my 22milliohm current-sensing shunt >resistor (labeled "22m" on the schematic) was really 22megaohms. The circuit >didn't really work after he made that substitution... :-) > >I take it your program elicits some warnings if it's trying to be "smart" and >discoveres that m/M confusion likely exists? No, I'm figuring it will eventually throw a mismatch as a warning. The m/M case is rare anyhow. John
From: Joel Koltner on 31 May 2010 23:16
"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message news:dot806hthadka7m7oqt76e1pv607q22382(a)4ax.com... > It wouldn't be hard to pile up a *lot* of microfarads of bypass caps > on one plane, scattered over many sheets of schematic. Enough to freak > out some LDOs that, on the power supply page, have an aluminum or > tantalum bypass. Have one of the kids write up a PowerBASIC program (or whatever their programming language of choice is) to find all the capacitors connected to a given net and add up their values? :-) That'd be a kinda cool macro, actually... |