How to make a fully fledged PC using the Raspberry Pi 2 and its GPIO pins
Raspberry Pi 3 models 3 and 3B feature the same ARM Cortex-A15 CPU as Raspberry Pi 1 models 3, but feature a new GPIO connector that is compatible with the Pi 2’s GPIO pins.
This allows you to use Raspberry Pi’s GPIO to control a Raspberry Pi with GPIO pins 2 and 3 connected.
The GPIO connector is located on the bottom of the Pi 3, and it’s possible to solder the connector onto a Pi 2 model.
There are no other GPIO pins to solder on to, but you can use the Raspberry PI 2 GPIO header to wire up the Pi’s two GPIO pins and GPIO pins 3 and 4 to the Raspberry Pis GPIO header pins.
In order to make this work, you’ll need to hook up the Raspberry pi’s GPIO headers to the Pi GPIO header pin 3 and GPIO header 2 to the GPIO header 4.
Once you’ve hooked up the GPIO headers, you can connect them to the USB pins of the Raspberry Model A or B, which you can then plug into the Raspberry 2 model’s GPIO header, which will then trigger the GPIO pins for the Raspberry.
The Raspberry Pi GPIO headers don’t need to be wired up in any particular order, so it’s a great solution if you have a Pi Model A, B, or C and are unsure if you need to wire it up in a particular order.
Raspberry Pi Model B GPIO Header (Model A, Model B) and GPIO Header Pin 1 (Model C, Model C+)