Rude eBay Vendor

Well, my response to that is "You probably don't need to buy anything from this vendor if they have no idea how (or inclination) to properly answer your questions."

I think the *best* answer to your question, though would come straight from the source; that is the author of the wiringPi library:

I hope this helps.

Yeah, I guess it helps. I never would have imagined that someone would add a third numbering scheme to the existing ones.

I do want one of these boards and this one is the cheapest. I expect I will order the board. But there is more than one way to skin a cat.

Some (well me) say that I added the first numbering scheme and the others followed.

Gordon

Must update that... One day..

The easiest way is to run

gpio readall

in a terminal. That way you get a picture of the GPIO connector on the Pi you're running it on with all the numbers you could ever want!

Gordon

I have to say, I am a bit more confused rather than less. On your web page you talk about three numbering schemes...

I get that the wiringPi is an arbitrary numbering scheme that abstracts the hardware and provides a means of controlling the I/O pins on the connector without changes between versions of the rPi. I don't understand what the other two are. I don't know if "native hardware pin numbering" means the pins on the CPU chip or the pins on the connector. Then "physical pin numbers" leaves me completely confused. What part of hardware is not "physical"?

Unless I am very much mistaken I would read it like this

Native Hardware pin numbers will be the pin numbers for the SOC as per the broadcomm documentation.

Physical pin numbers will be pin numbers on the 40 pin header.

I actually have wPi installed on my model 1B that runs the RASPBX phone system here, but I don't use it to operate the 8 relays that can be "dallied" as I didn't find it too confusing to count 1-8 as 17,18,27,22,23,24,25,4, the sequence is now hardwired into my brain :-) I did have to scratch my head to figure out why the 8th relay refused to work until I realized that 04 was wrong in the shell script, it was just 4. That's why I now write gpio in lower case!

One thing your site did teach me was that gpio2 and gpio3 don't need pullups, so these were my preferred inputs for the two door entry call buttons.

If you ever have the misfortune to use a Pi v1, then you'll need to remember 17,18, 21, 22, ...

and on a v1 those are bcm_gpio 0 and 1 ...

Cheers,

Gordon

Why would anyone care about the pin numbers on the SOC? Is it because the documentation of the SOC is in terms of those pin numbers? I would expect the SOC docs to mostly refer to the internal registers and only relate that to chip pin numbers in a table somewhere. In other words, I can't see much reason to worry with the SOC pin numbers, rather I would focus on the view from the software (register addresses and bits) and the view from the hardware (board connector pin numbers). SOC pin numbers are only useful if you are trying to trace out the connections using the board level documentation.

I recall reading from the Broadcom manual once and the docs are in terms of the internal registers.