According to this guide, only the following pins are available for my use:
2, 3, 4, 7, 8, 9, 10, 11, 14, 15, 17, 18, 22, 23, 24, 25, 27, with 28, 29, 30, 31
So that's 17 pins and then 4 on the header.
Now when I look at the pin-out for the model B+ board:
I see GPIO pins GPIO05, GPIO06, GPIO12, GPIO13, GPIO16, GPIO19, GPIO20, GPIO21 and GPIO26 are shown. Why can't I use these?
They are also listed here.
I am using a RPi Version 2 which I understand uses the same form-factor as B+ and need to know which pins I can use and which I can't. I just don't understand which pins I can and cannot use and if the above is correct, why I can't use them.