The problem I am having is that the B+ model has more GPIO pins than previous models. I'm not sure of the exact number, I've not counted and I don't think it matters for my questions.

raspberry pi A and B models

You can see that the A model (on the left) has less pins than the B+ model (on the right).

I have an addon board to do remote control plug sockets using RF. Here's the board:

addon radio transmitter

The addon board has exactly the right number of pins for an A model pi so it's easy to put it on the correct pins. Not so much for the B+ model pi.

How can I tell which pins to put the addon board on?

2 Answers 2


The first 26 pins (the number of pins on the model A and original model B Pi's) are the same. The model B+ and Pi2 have 40 pins. Raspberry Pi pinouts. The pins are numbered from left to right starting at the SD Card end of the board.

The problem you will have is that the female pin header on the add on board, will likely not clear the 14th row of pins. There are a couple of workarounds you can use.

  • Woah.. thanks for the detailed answer. I've not had any trouble with the header fitting past the 14th row. It's attached but still not doing what it should do. I've now tested the addon board with a Model A pi and it works to turn sockets off, but not on. On the Model B+ pi it doesn't turn sockets off or on.
    – Matt
    Commented Nov 20, 2015 at 22:29

Some time ago I updated Gordon Henderson's pins for the B+ This shows all the common numbering schemes for the pins.



as @steve-robillard said the first 26 pins are the same, unless you have one of the Rev 1 boards which have 3 differences (mainly I²C pins).

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