tac@sei.cmu.edu (Timothy Coddington) (03/15/88)
I hope what follows is informative to those who are interested in PCB design. I've included my original post to this newsgroup, and some of the better/more informative responses I got back. I've done some editing and have removed some names. If you have anything to add, I'd appreciate it if you'd e-mail me. As for AMS (see my original post, 2nd para), I Have an IMPORTANT WARNING - IT STINKS!!!!!!!!. It is full of bugs, and I've only gotten the run-around since I bought it from them. Since November I've been told - next week, next week. I've just about given it up for a loss. If anyone wants more information let me know. Otherwise, I'm still looking for a schematic capture/PCB layout/auto routing package/programs to use. >>>>>>>>>>>>>>>>>>>My original post<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< CAD/CAE tools are in wide spread use today. I lack the experience, time, and/or money to locate and evaluate those products/tools which can help me generate printed circuit boards. I would like to find any public domain, or commercial software tools which support the printed circuit board development process. For example, Schematic Capture, Net List Generator, PCB Layout Editor, Auto-Router, etc. I have a Compaq Portable, PC AT, or MicroVax II to run the tools on (prefer PC compatible). Many of the commercial vendors offer demonstration copies which can be freely distributed. **I've purchased and attempted to use Advanced Microcomputer System's **Cell, Pcpro, and Pcroute tools. The so called users manual is **inaccurate and incomplete. So far I've provided AMS with a list of **at least 30 bugs to correct. Several of them have cause complete **lockup of the system, and I've had to reboot. The advice and **instructions I've obtained over the phone, from AMS, have half **the time been incorrect. And, after all the trouble and hours of **frustration I went through I found out it doesn't route on single **layer boards, only 2 or more. If they could get rid of the bugs and make some of my suggested changes it would be a good product. However, I'm now stuck without a way to generate several prototype PCBs, which I don't have time to do by hand. I would like to hear from anybody who can offer some advice, knows where I can obtain this kind of software, or has experience with a particular system/package. I would also like some advice on etching boards, wave soldering, and pricing and availability of commercial services to do this kind of stuff (since these are prototype, maybe one-time boards I want to do as much as possible myself). Any input would be greatly appreciated. I prefer any response to come through mail. Thanks for taking the time. Tim Coddington 412-268-7712(w) 412-244-8557(h) arpa==> tac@sei.cmu.edu bitnet==> tac%sei.cmu.edu@uma.cc.cmu.edu csnet==> tac%sei.cmu.edu@relay.cs.net Disclaimer: These are my opinions. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< ----------------------Mail I received------------------------------------ >Subject: PC Layout > >You might wish to try the Visionics product. It does schematic >capture, simple simulation, and layout. Runs on a PC. They >have a new "greatly improved" version that will be available >at the end of February. I have yet to actually build a board >that I have layed out with their software but I have been happy >so far. > > ##############Name removed############## >----------------------Mail I received------------------------------- >Subject: Re: PCB design software > > >Well, I'm only a hobbyist, what do I know for expensive systems? > >But, the above aside, I bought the EE-designer package and I am very pleased >with it. It is, admittingly, in the low-end market ( i.e. don't build a service >bureau on it), but for me it is just great. Background: I make projects; >that means I design the device, I draw the schematics, I design the PCB and >I debug the hardware. If needed, I write the software, too. So I'm not using >the software all the time, maybe 20-30% of the time I use for electronics >(wich gives about 5-10 hours a week). > >The software has schematic capture, simulation and PCB design (with autorouter) >all integrated. Not very easy to learn, but easy enough. Not extremely powerful >but powerful enough for professional work (if not for full-time PCB design). > >I recommend it, provided your need is not too heavy and cost has some >meaning. (For the rich and heavy users, there exist much better systems; I >know none with better cost effectiveness.) >-- ############Name removed######## >----------------------Mail I received--------------------------------- >Subject: Re: PCB design software > > > >The following is a mail-message in response to a previous more or less simular >question (although the focus was different). Apart from the small remark I >added at the end, I think this is all I can do for you. Succes ! > >*********************************************** >> >>Two years ago, at my previous job with Philips in the Netherlands, I became >>heavily involved with selecting one of the then available CAD-software >>packages for schematic capturing and pcb-design. As we were involved with the >>design of switch mode power supplies, simulations were out of the >>question (then at least). So no advice or experiences on the simulation field. >> >>Perhaps the first thing to do is to make a list of your prerequisitions; >>things that such a CAD-tool absolutely should provide. >>Scratch all alternatives that don't meet your prerequisitions. (tough if there >>aren't any left :-) ) >>The rest is just a question of preferences and/or budget. >> >>Some of the most important items to us were: >>- What to do with the output >>A perfect pcb design on screen or floppy doesn't help you a lot if there is >>not an appropriate way to either make the film(s) yourself or have them >>post-processed for you. The same applies for the ability to make drilling >>tapes. >>If you decide to have your designs postprocessed (which you are most likely >>to do) the first thing you have to do is standardise on pad sizes. Most CAD >>packages will support 32 or 64 pad codes. This might seem a lot, but be >>aware that every combination of pad size and drilling diameter requires a >>unique pad code. Especially when you plan to design mixed prints (i.e. both >>leaded and surface mount devices in the same library) you run out of pad >>codes quite easily. Changing the pad code reference file at the >>postprocessing facility for every new design is not impossible but very >>hard to manage. >>- Our designs merely consisted of discretes. Therefore we had to be able to >>call a component during PCB design by its name, assigned during schematic >>capturing (e.g. R1 or C22). Amazingly, a number of packages only supported >>calling by type number (e.g. bc337) and/or library number. If you used more >>than one of such a component in your design, you never knew which one would >>be called. >>If you design circuits using a lot of IC's having more than one gate, >>latch, flip-flop, opamp etc. on one chip, it is most likely you want to call >>the component by its type number. Than, a very important feature might be the >>possibility of gate swapping. Some packages don't support this at all, some >>only allow you to interchange both in- and outputs of the gates (or >>whatever) on one chip, some even support multiple chip gate swapping. >>If this is not clear: suppose you use two four-gate nand chips. During >>schematic capturing you have to connect all gates. During PCB design, you >>discover it would be much more convenient to use gate #3 of chip #2 for a >>specific function than gate #1 of chip #1. Interchanging all connections to >>those gates is called gate swapping. The system should know you are allowed >>to swap two nand gates (if using the same supply) but not a nand and o nor >>gate. >>- Back annotation >>If using gate swapping (see above) or renaming components after having >>completed PCB design (useful for service purposes) you should change your >>schematics accordingly, in order to have a matching circuit diagram. >>As this is the reverse of the design direction, this is called back >>annotation. Depending on the nature of your designs this might be an >>important issue. >>- The use of off-grid components >>Most packages enable you to design in a grid of 1/80 or 1/40 inch. If you >>use special components with metric dimensions this might be unacceptable. >>If this is important to you, make sure off-grid components are also >>supported. >>- Variable track width >>Larger currents require wider tracks. Make sure you can already enter a >>track code at schematic capturing. There it is not to hard to indicate where >>higher currents might occur. >>- True outline screen representation >>If you design a PCB and only see lines for the tracks and x's for the pads >>it is very hard to judge if another track can be routed trough a certain >>narrow path. This is even harder if your designs contain a lot of different >>track widths. >>- Design rule checking >>After completion of your PCB design, a design rule checker can check if >>all design rules are met. These rules can concern *track to track distance >>*pad to track distance, *pad to pad distance etc. and can be very useful >>for a PCB design that is to be used in an production facility. >> >>Regarding the names you mention (pcad, orcad) I suppose you (as we did) are >>looking for a CAD package that can be ran on an IBM-pc compatible machine. >>If this is true make sure to run it on an AT (80286) instead of using a XT. >>Always use a hard disk. Get yourself a decent hi-resolution screen, preferably >>in colour. Use at least a 13 inch crt, but if you can afford it, bigger. >> >>In case you might be interested, we ended up buying Redcad from Racal Redac. >>It was the only one that met all our requirements. We had a special interest >>in the postprocessing part. >> >>The aspects involved with simulation were not evaluated by us, because only >>logical simulators were available. >> >>Hope this has been of help ! >> ########Name removed######## >************************************ >End of original mail-message > >The only thing I can add concerning your specific questions is, that Redcad >(our choise) also didn't support single layer autorouting. Neither am I aware >of any software package that does. Two layer autorouting does not perform that >well either. We didn't care; we hardly ever designed other than single layer >boards. > > #########Name removed############### >>-------------------------------------------------------------------------- Tim Coddington 412-268-7712(w) 412-244-8557(h) arpa==> tac@sei.cmu.edu bitnet==> tac%sei.cmu.edu@uma.cc.cmu.edu csnet==> tac%sei.cmu.edu@relay.cs.net Disclaimer: These are my opinions.