I actually like to go with option three, which is, find out what the Atmel / AVR / PIC / Embedded Processor / etc. is actually doing, that is how it is actually being used in the circuit, with inputs drawn as inputs, outputs drawn as outputs, busses drawn as busses, control lines drawn as control lines, so that the component itself somewhat explains itself, and so that the flow in and out of the part lends itself to good circuit flow and specifically to easy functional recognition.
As in make the whole schematic understandable, or at least more understandable. Yes this means that you may need to draw a different "atmel" symbol for different "projects" or "boards", but I think you'll find that if you break it up right and do a good job that it will be pretty much the same for most of your designs, or at least most of your designs from one engineer or programmer (this is because they tend to repeat themselves and use as much of the old design as possible each time they go off on a new project (as in the "it worked last time" and the "nothing ventured, nothing to fail" syndromes)). Anyway, flow? Oh yeah flow. That was something they stopped teaching and talking about around 20 years ago when everyone decided to go with the new "hierarchical" schematics where it all went on 27 sheets of "A" size paper which nobody could understand anyway, so the attitude became why spend extra time worrying about making the individual circuits or functional blocks easily recognizable or understandable since the whole thing is garbage anyway. As a side note, while it may require that the part be a little larger due to the extra text, If you simply go with the sequential 40 pin rectangle type of symbol, I would use the "full functional description" of the pin, or what I call the "dual description or name". For example, with a 40 Pin Atmel AT90S8515, just as shown in the data sheet, Pin 10 would be (RXD)PD0 and Pin 11 would be (TXD)PD1, because while the pins are in fact bits 0 and 1 of Port D, they also are dedicated to be used as the RXD and TXD lines for serial communications. Doing this on the schematic symbol will go along way in not only making the schematic much more understandable, but also enable you (or the engineer or programmer) to have a better chance to spot any errors due to miswiring, prior to casting the design in FR4. JaMi Smith * * * -----Original Message----- From: Matthew Leigh [mailto:[EMAIL PROTECTED]] Sent: Thursday, April 11, 2002 7:59 PM To: Protel EDA Forum Subject: [PEDA] Duplicate pins in schlib I'm drawing up a library component for an Atmel microcontroller, which has a large number of multi-function pins (for instance, pins 32-39 are either an 8-bit I/O port or half of the memory bus). I can see two ways of representing this in the schematic library: 1) Place 40 pins and give each one a title like "PA0 (AD0)". 2) Place one pin for each function but with duplicate pin numbers (so there's two of each pin, with different names). Which, or both, of these methods is legal (Protel 99SE) and which is advisable? Thanks Matthew Leigh * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
