In a schematic you can you use the @ notation to specify multiple pins with identical names for example GND@2. This doesn't seem to work in a package/board. For example an arduino board PCB has several identical pin names such as TXO or RXI. This is how it's shown in the datasheet as well as printed on the pcb so using incrementing numbers for all pins would be confusing. Even worse there are pins on 3 sides of the pcb and even a few miss aligned pins next to rows of pins adding to the confusion.

What is the proper way to name identical pads or a good way work around this issue?

Example board:

enter image description here

  • \$\begingroup\$ Good CAD programs separate pin number from pin name. You just increment the number and have the same name for different pins. \$\endgroup\$ – scld Apr 3 '17 at 20:12
  • \$\begingroup\$ Yeah, I curse Eagle at every step it's so bad. What would you say are some good CAD packages? Ideally not too obscure/niche/crazy expensive? \$\endgroup\$ – DominicM Apr 3 '17 at 22:48
  • \$\begingroup\$ Altium, DxDesigner, and Orcad are all pretty good. Though, every CAD tool is going to have its learning curve and its quirks. I think you'll find things you like as well as things you don't regardless of which tool you use. \$\endgroup\$ – kjgregory Dec 11 '17 at 15:27

The signal names you see printed on a PC board are usually just text that the designer has manually placed on the silkscreen layer - they have no automatic association with actual signal names, as far as the CAD program is concerned.

If the same signal appears on multiple connectors, there is no problem having identical labels each time that signal appears.

  • \$\begingroup\$ See edit. How would you handle naming the pads in the image. It would be confusing to match pins to pads with those extra 4 pads not in a row with the rest. \$\endgroup\$ – DominicM Apr 3 '17 at 20:07
  • \$\begingroup\$ @DominicM: If you want to identify those pads, you just have to squeeze the names in wherever/however they fit. \$\endgroup\$ – Peter Bennett Apr 3 '17 at 22:37
  • \$\begingroup\$ I don't mean the silkscreen, I am of course talking about naming the pads in the package editor, specifically the issue with duplicate names. \$\endgroup\$ – DominicM Apr 3 '17 at 22:57
  • \$\begingroup\$ @DominicM: In CAD systems I've used, the pad name is defined in the connector definition, and does not necessarily have any relation to the signal carried by that pin. A signal can connect to any number of pads in a connector with no problem, and no change of name. If I designed that board, I would probably make the pins around the edge as three separate connectors, and the extra four pins as two, two pin connectors, but it would also work to make all pins as one large connector, with pins numbered from 1 to whatever. \$\endgroup\$ – Peter Bennett Apr 3 '17 at 23:14

Generally speaking, if I have to specifically number the pads at the perimeter of a PCB, I number the pads on the PCB as if it were a DIP package. Looking at your board, bottom left would be pin #1. Continue counter-clockwise until you get to the highest-numbered pin on the top left.

If you have pads on all 4 sides of a PCB, pick one side as bottom and number as described above.

  • \$\begingroup\$ Any references to DIP naming convention? So start from bottom left then proceed to the end keeping left as much as possible? Or keep to outer most edge of the board? How would you handle the pins close to A3 and 12? What if some pins are positioned randomly in the middle somewhere? \$\endgroup\$ – DominicM Apr 4 '17 at 8:58

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.