Now that your board works, you're going to add peripherals so that it can operate as a standalone computer system. This step is optional, as in future, your projects will often be in systems where you won't connect directly to the board with a keyboard, mouse, and display. However, this can be a great learning step, and is especially useful if you need to do some debugging on the system.

You'll need the following peripherals:

You may have most of this stuff already, but if you don't, there are some things to consider before buying additional equipment. Let's start with the keyboard and mouse. Most mice and keyboards have separate USB connectors. You'll notice, however, that your Raspberry Pi has only two USB ports. If you want to connect other devices, you may want to choose a keyboard that has a built-in mouse pad. That way, you only have one USB connection for both the devices.

You may also want to consider purchasing a powered USB hub. Before deciding on the hub to connect to your board, we need to understand the difference between a powered USB hub and one that gets its power from the USB port itself. Almost all USB hubs are not powered; that is, we don't plug in the USB hub separately. The reason for this is that almost all of these hubs are hooked up to computers with very large power supplies, and powering USB devices from the computer is not a problem. This is not the case for our board. The USB port on our board has very limited power capabilities, so if we are going to hook up devices that require significant power (for instance, a WLAN adapter or a webcam), we're going to need a powered USB hub; one that provides power to the devices through a separate power source. The following is an image of such a device:

Notice that there are two connections on this hub. The one to the far right is a power connection, and it will be plugged into a battery with a USB port. The connection to the left is the USB connection, which will be plugged into Raspberry Pi.

Now, you'll also need a display. Fortunately, your Raspberry Pi offers lots of choices here. There are a number of different video standards; the following image is a reference to some of the most prevalent ones:

There is an SVideo output and an HDMI connector on Raspberry Pi. The easiest method to create a connection is to connect the board directly to a monitor or TV that has an SVideo or HDMI input; however, you'll need to buy a cable to go between the two. Check the video input on the monitor or TV; it will normally either have a set of RCA jack inputs, normally colored yellow (video), white (left-audio), and red (right-audio), or a multipin SVideo connector. If you are connecting using the RCA jack inputs, connect the output of the Raspberry Pi video to the yellow input. The output of Raspberry Pi is an RCA jack output, so make sure you get a cable, with or without adapters, so that you can make the proper connection.

If you want to use the HDMI output, simply connect your cable with regular HDMI connections to Raspberry Pi and your TV or monitor that has an HDMI input connector. HDMI monitors are relatively new, but if you have a monitor that has a DVI input, you can buy adapters relatively inexpensively that provide an interface between DVI and HDMI. The display I use has a DVI input.

Don't be fooled by adapters that claim that they go from HDMI or DVI to VGA, or HDMI or DVI to -video. These are two different kinds of signals: HDMI and DVI are digital standards, and VGA and SVideo are analog standards. There are adapters that can do this, but they must contain circuitry and require power, so are significantly more expensive than any simple adapter. Now that you have all the bits and bobs, connect the USB hub to the standard USB port, the keyboard and mouse to the standard USB port, and the display to the proper connector as shown in the following image:

Once all these are connected, you are ready to plug in Raspberry Pi. I am using a standard USB 5 volt power supply. Make sure you connect all your devices before you switch on the unit. Most operating systems support the hot swap of devices, which means you are able to connect a device after the system has been powered; but this is a bit shaky in the embedded environment. You should always cycle power when you connect new hardware.

Unfortunately, even though your hardware configuration is complete, you'll need to complete the next section to switch on the device. So let's figure out how to install an operating system.