To build home automation with this system you only need RapsberryPi for the core. What it is? Wiki page says
The Raspberry Pi is a low cost, credit-card sized computer that plugs into a computer monitor or TV, and uses a standard keyboard and mouse. It is a capable little device that enables people of all ages to explore computing, and to learn how to program in languages like Scratch and Python.
The original Raspberry Pi and Raspberry Pi 2 are manufactured in several board configurations through licensed manufacturing agreements with Newark element14, RS Components and Egoman. These companies sell the Raspberry Pi online.Egoman produces a version for distribution solely in China and Taiwan, which can be distinguished from other Pis by their red colouring and lack of FCC/CE marks. The hardware is the same across all manufacturers.
The original Raspberry Pi is based on the Broadcom BCM2835 system on a chip (SoC),which includes an ARM1176JZF-S700 MHz processor, VideoCore IV GPU,and was originally shipped with 256 megabytes of RAM, later upgraded (models B and B+) to 512 MB.The system has Secure Digital (SD) (models A and B) or MicroSD (models A+ and B+) sockets for boot media and persistent storage.
In 2014, the Raspberry Pi Foundation launched the Compute Module, which packages a BCM2835 with 512 MB RAM and aneMMC flash chip into a module for use as a part of embedded systems.
The Foundation provides Debian and Arch Linux ARM distributions for download.Tools are available for Python as the main programming language, with support for BBC BASIC(via the RISC OS image or the Brandy Basic clone for Linux),C, C++, Java,Perl and Ruby.
As of 18 February 2015, over five million Raspberry Pis have been sold.While already the fastest selling British personal computer, it has also shipped the second largest number of units behind the Amstrad PCW, the “Personal Computer Word-processor”, which sold eight million.
In early February 2015, the next-generation Raspberry Pi, Raspberry Pi 2, was officially announced.The new computer board will initially be available only in one configuration (model B) and features a Broadcom BCM2836 SoC, with a quad-coreARM Cortex-A7 CPU and a VideoCore IV dual-core GPU; 1 GB of RAM with remaining specifications being similar to those of the previous generation model B+. Crucially, the Raspberry Pi 2 will retain the same US$35 price point of the model B,with the US$25 model A remaining on sale.