Post by thread:[EE]PSPICE help

Hi Am I correct in assuming that some of you guys at least would have experience of PSPICE? I've downloaded the free 'student' version, and I have a question. I managed to suss out how to model a switch opening or closing after a period of time, but is it possible to model a 'noisy' switch change at all? Also, PSPICE to me so far seems very good for modelling individual little modules, but I'm not sure how I'd go about drawing the schematic for my whole project, ready to feed in to something to lay out a PCB - how can I put in place a dumb 16/18pin IC to represent a PIC or any other IC not in the library? or a connector strip, ICP programming header? Am I using the wrong tool for what I need? Regards, Mark ============================================================================== This message is for the sole use of the intended recipient. If you received this message in error please delete it and notify us. If this message was misdirected, CSFB does not waive any confidentiality or privilege. CSFB retains and monitors electronic communications sent through its network. Instructions transmitted over this system are not binding on CSFB until they are confirmed by us. Message transmission is not guaranteed to be secure. ============================================================================== ____________________________________________

> I've downloaded the free 'student' version, and I have a question. I > managed > to suss out how to model a switch opening or closing after a period of > time, > but is it possible to model a 'noisy' switch change at all? > > Also, PSPICE to me so far seems very good for modelling individual little > modules, but I'm not sure how I'd go about drawing the schematic for my > whole > project, ready to feed in to something to lay out a PCB - how can I put in > place a dumb 16/18pin IC to represent a PIC or any other IC not in the > library? or a connector strip, ICP programming header? > > Am I using the wrong tool for what I need? > > Regards, > Mark > > You can model your "noisy" switch a few different ways: 1) Add additional resistance to the model (I'm assuming you are using the voltage controlled switch or current controlled switch). You can use the built-in parameter or add your own to the net list to simulate cross-talk. 2) Add external capacitance to the net list, also inductance to simulate leads, etc. 3) Drive the switch with a pulse or custom waveform to make it "chatter" (ie contact bounce of a mechanical switch or relay) 4) Some versions of spice include a "noise" waveform, don't know about the student edition of Pspice. That could be "injected" on either side of the switch through a capacitor. 5) Some versions of spice include "noise" analysis where the Johnson noise of resistors is included. As far as having a tool for doing schematics and small layouts, Eagle has a "free" version and various levels of "paid" versions depending on what you need. There have been numerous threads on PicList about CAD software so perhaps the archive can disgorge some information for you. Otherwise you could start a weekend CAD-religion war and see what kind of responses you get... :-) Rob Young ____________________________________________

>As far as having a tool for doing schematics and small >layouts, Eagle has a "free" version and various levels >of "paid" versions depending on what you need. You may like to look at the demo copy of Orcad. The CD comes with demo versions of PSpice, capture and Layout, which are not time limited as far as I can see, but are definitely net and pin limited. There is also a demo version of Specttra router, but cannot save the result. Another possibility for PSpice is to get the Linear Technology Switcher Cad package, which although aimed at doing switching regulators, some on this list have reported that it works admirably as a PSpice program for anything.Not tried it for that myself though. ____________________________________________

{Quote hidden}>-----Original Message----- >From: spam_OUTpiclist-bouncesTakeThisOuTmit.edu [.....piclist-bouncesKILLspam@spam@mit.edu] >Sent: 24 November 2004 16:02 >To: Microcontroller discussion list - Public. >Subject: Re: [EE]PSPICE help > > >>As far as having a tool for doing schematics and small layouts, Eagle >>has a "free" version and various levels of "paid" versions >depending on >>what you need. > >You may like to look at the demo copy of Orcad. The CD comes >with demo versions of PSpice, capture and Layout, which are >not time limited as far as I can see, but are definitely net >and pin limited. There is also a demo version of Specttra >router, but cannot save the result. > >Another possibility for PSpice is to get the Linear Technology >Switcher Cad package, which although aimed at doing switching >regulators, some on this list have reported that it works >admirably as a PSpice program for anything.Not tried it for >that myself though. We often use Switchercad to verify operation of smaller circuits/sub circuits. For the price it's really an excellent package. The only PITA is adding spice models to the library which requires a bit of manual editing of files, but not too difficult. Regards Mike ======================================================================= This e-mail is intended for the person it is addressed to only. The information contained in it may be confidential and/or protected by law. If you are not the intended recipient of this message, you must not make any use of this information, or copy or show it to any person. Please contact us immediately to tell us that you have received this e-mail, and return the original to us. Any use, forwarding, printing or copying of this message is strictly prohibited. No part of this message can be considered a request for goods or services. ======================================================================= ____________________________________________

piclist-bounces@mit.edu wrote: > Another possibility for PSpice is to get the Linear Technology > Switcher Cad package, which although aimed at doing switching > regulators, some on this list have reported that it works admirably > as a PSpice program for anything.Not tried it for that myself though. I downloaded it after reading a post from Dwayne Reid (I think?). I have used it several times to evaluate different configurations and it works as advertised. I've used to to 'play' with Roman Black's switcher and Olin's boost circuit. Software is easy to learn/use. It has a small component library, but it's fairly easy to add parts. And the price is right. ____________________________________________

Michael Rigby-Jones wrote: >> <> >> We often use Switchercad to verify operation of smaller circuits/sub >> circuits. For the price it's really an excellent package. The only >> PITA is >> adding spice models to the library which requires a bit of manual >> editing of >> files, but not too difficult. > Could you perhaps give me a short description on how you add spice models to the library? I've been trying to import different kinds of models for a while without success and I haven't been able to find any help in the help file. I also find the SwCAD 3 a great spice software if it wasn't for the library limited to mostly Linear devices. However considering it´s price which is free, I find it very valuable. Regards, Johan ___________________________________________

Which "student" version do you have? The slightly earlier Pspice 8.0 is reputed to be somewhat more friendly than the latest version which I think is Orcad based wrt the schematic capture. I don't know of any "noisy switch" model. You'll have to generate what you want from basic components. - E.g. drive a Vpulse from an ascii file & use this to drive a transistor or voltage operated switch. (Sbreak) There are limitations wrt adding new spice models but it's not too hard, and many manufacturers now produce spice models for their components that are downloadable. (Philips is a good example). PCB layout is best left to a dedicated program like eagle. It does mean you have to enter the schematic twice but the Pspice version gererally needs considerable editing anyway before converting to a "real" layout. Voltage supplies etc have to be replaced by connectors, gain blocks by real opamps and transistor types checked for correct pinout etc. The version of Pspice I use (8.0) is quite restrictivein what it allows you to do as far as generate PCB components. SMT parts are particularly restricted. Also you ofen end up running out of components or nets as far as the evaluation version is concerned anyway - particularly if you use a complex opamp model etc. Some drawing programs will produce a netlist for spice analysis as well as perform the Schematic capture & PCB layout - protel (& Orcad ?) etc. But these do not always have free versions. I don't know if Eagle will generate a suitable netlist or not. Just always be aware that you are using a model - in real life the components will perform differently. Richard P Hi Am I correct in assuming that some of you guys at least would have experience of PSPICE? I've downloaded the free 'student' version, and I have a question. I managed to suss out how to model a switch opening or closing after a period of time, but is it possible to model a 'noisy' switch change at all? Also, PSPICE to me so far seems very good for modelling individual little modules, but I'm not sure how I'd go about drawing the schematic for my whole project, ready to feed in to something to lay out a PCB - how can I put in place a dumb 16/18pin IC to represent a PIC or any other IC not in the library? or a connector strip, ICP programming header? Am I using the wrong tool for what I need? Regards, Mark ____________________________________________

At 12:20 PM 11/24/2004, Johan Baarman wrote: >Michael Rigby-Jones wrote: > >>><> >>>We often use Switchercad to verify operation of smaller circuits/sub >>>circuits. For the price it's really an excellent package. The only PITA is >>>adding spice models to the library which requires a bit of manual editing of >>>files, but not too difficult. >Could you perhaps give me a short description on how you add spice models >to the library? I've been trying to import different kinds of models for a >while without success and I haven't been able to find any help in the help >file. I also find the SwCAD 3 a great spice software if it wasn't for the >library limited to mostly Linear devices. However considering it´s price >which is free, I find it very valuable. Its reasonably easy to do. But the best advice I can give you is to head over to the "LT Spice" forum on Yahoo Groups and check out their archives. You will also find files for hundreds of additional devices. The group owner (Helmut) spends an incredible amount of time keeping the messages and files organized and all off-topic or spam messages are ruthlessly purged. Its a very good resource - on par with our own PICList. It took me a while to find out about the YahooGroups LT Spice support forum - I had previously tried searching on the current software package name (SwitcherCAD III) and nothing showed up. It was an off-hand remark from SwitcherCAD's author (Mike Engelhardt) that put me on the right track. For what its worth, I use a pair of off-line readers for searching YahooGroups archives: PG Offline for messages and GroupFetch for files. Both are needed: PG Offline works extremely well for reading or searching messages but doesn't deal with the files in any way; GroupFetch handles the files nicely but is a pig when saving the messages. The difference is that PG Offline saves message text in a standard Access database (small and quick); GroupFetch saves each message as a separate *LARGE* HTML page (huge and slow). The LT Spice database generated by PG Offline zips up to about 4 MB for those who might want a copy. Also for what its worth, I've spent a couple of hundred hours or so over the past 6 months doing some fairly involved simulation with Switcher CAD III - the results match what I see when I build up the circuits. The bang for the buck is just incredible. dwayne -- Dwayne Reid <dwaynerKILLspamplanet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 20 years of Engineering Innovation (1984 - 2004) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. ___________________________________________

> Which "student" version do you have? > The slightly earlier Pspice 8.0 is reputed to be somewhat > more friendly > than the latest version which I think is Orcad based wrt the schematic > capture. I have the latest OrCAD offering. I'm getting along reasonably well, but it's far from intuative - I guess you need to know what you're doing with it!! > PCB layout is best left to a dedicated program like eagle. It Yep, I downloaded Eagle a few weeks back, but found that to be incredibly unintuitive, and I had no idea how to drive the program at all. Maybe I'll have another play. Regards, Mark ============================================================================== This message is for the sole use of the intended recipient. If you received this message in error please delete it and notify us. If this message was misdirected, CSFB does not waive any confidentiality or privilege. CSFB retains and monitors electronic communications sent through its network. Instructions transmitted over this system are not binding on CSFB until they are confirmed by us. Message transmission is not guaranteed to be secure. ============================================================================== ____________________________________________

>PCB layout is best left to a dedicated program like eagle. >It does mean you have to enter the schematic twice but the >Pspice version gererally needs considerable editing anyway >before converting to a "real" layout. Hmm, an integrated package like Orcad does allow circuit entry only once. However PSpice does have a problem under these conditions - it cannot handle European type value designations like 4k7, it has to be done as 4.7k. There may be times when it is necessary to add some stray inductance or capacitance to allow for circuit strays, but this is very dependant on the device models, and how good they are. ____________________________________________

Dwayne Reid wrote: {Quote hidden}> At 12:20 PM 11/24/2004, Johan Baarman wrote: > >> Michael Rigby-Jones wrote: >> >>>> <> >>>> We often use Switchercad to verify operation of smaller circuits/sub >>>> circuits. For the price it's really an excellent package. The only >>>> PITA is >>>> adding spice models to the library which requires a bit of manual >>>> editing of >>>> files, but not too difficult. >>> >> Could you perhaps give me a short description on how you add spice >> models to the library? I've been trying to import different kinds of >> models for a while without success and I haven't been able to find >> any help in the help file. I also find the SwCAD 3 a great spice >> software if it wasn't for the library limited to mostly Linear >> devices. However considering it´s price which is free, I find it very >> valuable. > > > Its reasonably easy to do. But the best advice I can give you is to > head over to the "LT Spice" forum on Yahoo Groups and check out their > archives. You will also find files for hundreds of additional devices. > > Thanks Dwayne. I will check it out. Johan ___________________________________________

On Thu, 25 Nov 2004, Mcgee, Mark wrote: >> Which "student" version do you have? >> The slightly earlier Pspice 8.0 is reputed to be somewhat >> more friendly >> than the latest version which I think is Orcad based wrt the schematic >> capture. > I have the latest OrCAD offering. I'm getting along reasonably well, but it's > far from intuative - I guess you need to know what you're doing with it!! > >> PCB layout is best left to a dedicated program like eagle. It > Yep, I downloaded Eagle a few weeks back, but found that to be incredibly > unintuitive, and I had no idea how to drive the program at all. Maybe I'll > have another play. I found eagle reasonably easy to learn *after* I read the manual and a quick intro written by someone (on the web). I say *after* because before that attempts to click my way through the program before reading up failed miserably. I think that eagle was born command-mode and the gui was added afterwards (autocad is the same afaik). Once you understand how it works it's reasonaby easy to use. Peter ____________________________________________

Peter L. Peres wrote: > I found eagle reasonably easy to learn *after* I read the manual Now c'mon Peter, isn't it a bit unreasonable to expect anything else from any complicated and rich app? If James weren't listening in, I would have said something like "Well, duh!", but since he is I won't ;-) > I think that eagle was born command-mode and the > gui was added afterwards (autocad is the same afaik). I don't know if it started command mode only, but it does seem that all the GUI interactions are layered onto the command mode interface. I think this is one of Eagle's great strengths. This guarantees that anything you can do with a mouse can also be done with a command. I often type commands for simple operations because it's easier and much faster than using the mouse. This scheme also allows anything to be done from a script. And the ULP feature allows programmatic access to the database so that it is actually possible to fill in difficult details like exact coordinates into those scripts. If you're just learning Eagle, don't worry about ULPs for now, but do try to learn the command set. That will help a lot once you do get into ULPs. It took me a while to get comfortable with ULPs, but they are pretty straight forward once you get the hang of them. Getting over the big hump for me was when I finally sat down and merged all the individual help topics in the ULP chapter into one single PDF file that I could print out, read, and scan. I've just recently written ULPs for creating a part index. This makes a part easy to find on the schematic and on the board. I've got another one that sets up a board for printing on a black and white printer that shows coordinate axes along the bottom and left, the silk screen, and top layer of copper. This is used together with the part index to find a part on the board. ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com ____________________________________________