On Thu, Mar 19, 2009 at 10:41 PM, Mark Rages <markra...@gmail.com> wrote: > 2009/3/19 Peter TB Brett <pe...@peter-b.co.uk>: >> On Thursday 19 March 2009 21:58:59 Josh Jordan wrote: >>> I prefer to use actual pinouts in my schematics for two reasons: It helps >>> you with chip placement because naturally you will tend to place symbols >>> and lines to get the fewest line crossings. Going to layout after you have >>> already decided the best general position for parts makes it much easier. >>> The second reason is that later on it will be easy to look back to a >>> schematic that has a similar layout as the board and the same pinouts. >> >> We'll have to agree to disagree. When I look at a schematic, I want to be >> able >> to quickly and easily work out what the circuit is designed to do, and having >> the pins on my symbols arranged by function and bus offset rather than by >> physical position helps a great deal. >> >> What you're doing completely defeats the point of having separate schematic >> and layout diagrams, IMHO. >> >> What do you do about parts that have different pinouts depending on what >> package they're in? >> >> Peter > > Of course you use the place the part on the schematic with the pinout > you are using. > > When you are troubleshooting a circuit with a scope or analyzer, it > adds an extra decoding step to have the pin order scrambled. And it > really is annoying when you're trying to look at the schematic to see > where your 64-pin micro has an unused pin free. >
Resurrecting this old thread as I just ran across an example of worst-practices regarding IC layout: http://live.midwesttelecine.com/Screenshot-PIC18F87J50%20FS%20USB%20Plug-In%20Module%20User's%20Guide.png (or http://tinyurl.com/c97tsp) This schematic combines the inconvenient form of a physical-ordered layout with the confusion of pins moved around, and all to a bunch of named nets anyway. (Just for the record, this is a dev board with no predefined function, and a high likelihood that the end user will be scoping signals and attaching other circuits, so IMHO physical order is called for.) Regards, Mark markra...@gmail -- Mark Rages, Engineer Midwest Telecine LLC markra...@midwesttelecine.com _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user