Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It only takes a minute to sign up.
Sign up to join this community
Altium (and I'm sure other PCB Design software) supports both numeric and alpha for pin designator. This is not the pin display name, like you would see on a schematic. This is how the footprint will align with the schematic symbol.
I've used pin numbers to align symbols to footprints in the past, but I'm curious what the general practice is - pin numbers vs pin names ?
Are there any benefits (short term or long term) to choose one or the other ?
If in doubt, use the same designators that the datasheet for the part is using. Usually, datasheets use simple numbers for pins.
Some parts require alpha-numeric string for pin "number".
Both drawings from datasheet for MSP430F5500.
In my experience (Protel/Altium and KiCad), the pin number on the schematic symbol must match the pin number on the PCB footprint. This pin number may be a number, letter, or any combination (the pin numbers on diodes are usually "A" and "K").
The pin name shown on (usually inside) the schematic symbol is not used to link between schematic symbol and PCB footprint.
I would say convention is on a square or rectangular parts or a part where all the pins are along the outside they are numbered.
Anything that is in an array with pads underneath the part is typically in an alphanumeric grid. For example bga, PGA, lga, etc.
Benefits? Well most people do it that way :). This will most likely march the datasheet. For a rectangular part I expect to be able to count around the outside of the part to find my place when debugging.
For bga where you could have 2000 pins it would get a little messy with the large numbers. Plus it's easy to find your way around in review or debug (or when designing your pin map if you've made the asic). A2 is right above b2, but if it was numerical you'd have to count or do some math in your head to find the next pin below. Again this will likely match most datasheets keeping in mind they often skip ambiguous letters like O.
Just some thoughts hope it's helpful.
For simple components (diodes, transistors) it's convenient to use alpha names in footprint - it allows to use one graphical component with multiple footprints. For ICs is more convenient to use names as is in datasheet.
