Personal Pi - Part #1.5

Hello everyone!

I know I told you at the end of my last entry that the next one would be about PCB modification of the portable DVD player board. However, my Raspberry Pi arrived today, so I figured I'd do an in-between entry to explain the Pi and the steps necessary to get it running for the first time. So here you go, the Personal Pi Part #1.5!

First of all, a little background--

What is a Raspberry Pi? The Pi is most often described as a credit card sized, single board computer. Originally developed in the UK for educational purposes, its popularity has spread far beyond educational environments among electronics, programming, and computing enthusiasts around the world. Like the Arduino, the Raspberry Pi is a single-board device that combines practically all necessary components, equipment, connections, and software required in order to use it right out of the box. However, it is much different from the Arduino in the sense that it has a microprocessor built into it, rather than just a microcontroller like the Arduino uses. This is what sets the Pi apart, turning into an actual computer.

In case you have never seen a Raspberry Pi before, here's what it looks like.
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Starting at the top left and working my way around clockwise, the following are the connections shown:

(1) GPIO Header
If you bought the Raspberry Pi so that you can control motors, lights, and what not over the internet, this is one of the most important connectors you'll use. GPIO (general purpose input output) is basically what you have on an Arduino. They are pins you can control through software. You can turn them on or off if they are set as outputs, or you can read digital sensor information if they are set to inputs. There are two rows of 13 pins, making 26 pins in total. Included in the 26 are three power pins (one that supplies 3.3 volts, one that supplies 5 volts, and one ground), 6 unused pins, and 17 GPIO pins.
I have not yet decided if I will make a GPIO extension to make the pins usable on the Portable Pi or not. I think I would just like to get the setup running first, then I will start worrying about the extras.
(2) Composite Video
This is the type of video output jack you see on a lot of VCRs and DVD players. Often associated with CRT TVs and RCA cables (the ones with yellow, red, and white plugs), this is a video connector that has all but faded away with the introduction and popularization of HDMI technology. Since the portable DVD player I am using does not have an HDMI input, but does have an A/V (audio/video) input, this is the connector I will be using do display the Pi output on the LCD screen.
(3) Headphones
Little explanation is needed here. This is a standard 3.5mm audio/headphone connector that you find on just about every piece of audio equipment these days, from tape players to CD players, to MP3 players, to FM transmitters, and so on. I will be using this audio output to drive the internal speakers of the portable DVD player, as well as routing the audio through to the existing headphone jack on the player.
(4) 2x USB
The model of Raspberry Pi that I purchased was the model B. This particular model contains two USB 2.0 ports. A simpler model (model A) contains only one USB port, but since I will be using mine as a computer, I want to be able to plug in a keyboard and a mouse. I may attach a USB WiFi dongle as well, in which case I will use a two-in-one USB keyboard and mouse. The USB ports on the Raspberry Pi should be able to recognize just about any USB devices that work on any other computer, making it a very convenient and useful connector to have.
(5) Ethernet
The Raspberry Pi includes a standard RJ-45 ethernet connector to allow for wired internet access. I have not yet decided if I will be using this or just the WiFi dongle, but I will be keeping my options open.
(6) CSI
The CSI (Camera Serial Interface) connector is useful if you have a cell phone camera that you would like to incorporate into a project. Many cell phones have these connectors internally and have their built-in cameras already connected at the factory. However, if you're like me and enjoy taking things apart, you may have a few cameras just lying around and no easy way to use them. The Pi has the ability to control and read from such cameras. I will not be using this connector in the Personal Pi project.
(7) HDMI
The HDMI (High-Definition Multimedia Interface) is a very useful connector to have when using your Pi with an LCD monitor and high definition audio. It combines the audio and video wiring into a single cable, and can transfer high quality images and sound to your device. Unfortunately my portable DVD player predates this technology, so I probably won't be using this connector. However, at some point in the future I may extend the port to the outside of the DVD player case to allow for the connection of an external monitor.
(8) USB Power
This connector is used to supply power to the Raspberry Pi. It uses a micro-USB connector that matches most modern ones used for phones. However, it is very important that you supply it with 5 volts at between 700mA and 1200mA of current in order for it to operate correctly. If you supply it with more than 5 volts you can destroy the Pi, and if you supply it with less than 5 volts it may not run at all. Furthermore, if you supply it with less than 700mA, it may begin to not operate as expected, especially if you have a lot of external devices attached to the Pi.
(9) SD
On the underside of the board (not visible in the picture) you will find a full-sized SD card slot. You can think of the SD card as the "hard drive" of your "computer". It contains the operating system image that runs on your Pi, and stores any files associated with it or programs you install. For most images you will need a 4GB+ SD card. To be safe I purchased a 16GB one, so it should last a while (I was planning on an 8GB but the 16GB card was on sale for $16.99 USD :D). I will cover the installation of the OS and setup of the pi in a few moments.
(10) DSI
The final connector on the Raspberry Pi is the DSI (Display Serial Interface) which, like the CSI connector, is designed for mobile phone use. It is designed for modern LCD screens found on mobile phones and some other devices. After examining my portable DVD player connectors, it appears the screen does, in fact, have a DSI cable. However, I have opted to stick to my original plan (using the composite video) for a few reasons, mainly the fact that all of the power circuitry is already included with the screen. I will not be using the DSI connector in my project.

Some models of the Raspberry Pi also have a JTAG header just to the right and down slightly from the composite video output. However, this part of my board is not populated, and I will not be using it in my project, so I won't discuss it any further.

Now that we've covered what the Raspberry Pi is and all the connectors it includes, let's move on to flashing the SD card and setting up the Pi for its first boot. Considering this post is much longer than I had ever planned, I think I will break this into two parts at this point. The next entry will be a tutorial on how to prepare the Raspberry Pi for its first boot, and then we can continue with the project on the next entry after that.

I hope you all have enjoyed this brief overview. If you have any questions or comments, please feel free to leave a message for me and I will respond as soon as I can.

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