Wednesday, March 20, 2013

Raspberry Pi Ingredients

In this post I discuss the additional items you need to get your Raspberry Pi up and running.

Previously I gave a brief overview of boards available and recommended that you purchase a Model B Rev 2 board, if you're in the market for a new Raspberry Pi. Once you've purchased your Pi you'll find you also need a few supporting accessories to get it up and running. I'll briefly discussion each of these items below.

Pi Power
The Pi can be powered by the same micro USB adapter that is commonly used with many smart-phones. If you already have one of these adapters it might work okay, but you need to verify the amount of amperage the adapter supplies. The general recommendation for the Pi (according to the the Raspberry Pi foundation) is a minimum of 700ma. Most cellphone chargers have that rated output, but your amperage may vary. Depending on the quality of the power supply, it may or may not deliver the stated output. If it doesn't you'll find that your Pi shuts down or locks up randomly, especially when you plug in a USB device. If you experience any of these issues with your Pi you'll probably need another adapter. You can find recommended adapters from stores such as AmazonMCM or Adafruit (also in the link below regarding verified peripherals). One final consideration: if you wish to over-clock your Pi   (which I'll discuss in the next post) you may experience boot issues (unable to mount root fs) if your power supply isn't up to spec. 

The HDMIs Have It
The Pi has two types of video output - composite and HDMI. Although it's technically possible to use the composite connection to a TV, HDMI is the better choice as far as resolution and pixel density are concerned. Composite, on the other hand, can be quite useful for projects that include their own small form-factor video panel. 

My setup also makes use of an HDMI receiver which handles the sound and TV connection. This setup works well, but sometimes there are quirks - if the Pi is powered on after the receiver I've seen issues where the receiver believes there is no video input. Fortunately that's easy to resolve by simply cycling power to the Pi. This quirk is the result of the Pi attempting to determine the attached display device and set the appropriate output mode. In future posts I'll discuss some of the tricks you can use in configuration to force the Pi to select default video modes, regardless of the type of device connected. This also allows using the Pi without a display -- a so-called "headless" configuration that's useful for remote connections, such as SSH and VNC. Again, I'll discuss how to setup these options in future posts.

It's All In the Cards
The Pi uses a full-sized SD card as its hard disk. Since that's the case you'll want to choose an SD card with plenty of room and fast read/write speeds. I recommend an 8GB card as a minimum. This allows approximately 7GB of extra space with the Raspbian ("wheezy") distribution. According to the foundation the Pi supports card sizes from 2-32GB. It also qualifies this statement by saying that the Pi supports most cards in this range. At the end of this post I'll provide a link to hardware that's been certified to work with the Pi. It's probably best to either look for items on this list, or look for user reviews which indicate a particular item works well with the Pi. As far as speed goes - SD cards are divided into classes, where higher class numbers indicate better read/write speeds. The predominate choices are between class 4 and class 10 cards. Since there's very little price difference you're better off buying the faster class 10 card, if you're in the market for a new one.

Get Connected
You can network your Pi in two different ways: using the built-in Ethernet port, or by purchasing an external USB wi-fi adapter. Obviously there are some tradeoffs with either approach. While the Ethernet port provides the fastest throughput, it limits portability. The USB wi-fi adapter solves the portability issue, but ties up a valuable USB port and delivers a lower throughput, especially when you're more than 10-15 feet away from your router. The ultimate decision between these two approaches is based on how you plan to use your Pi. If you choose the wi-fi route, you'll again want to look at the recommended hardware list or refer to reviews of items you're interested in purchasing. 

The Pi supports most USB keyboards and mice, using either a direct USB connection or a USB-wireless connection. If you're in the market for a new keyboard/mouse I recommend that you look at a wireless combo solution. This lets you use only one USB port to accommodate both inputs. Of course, you can always expand the Pi's USB ports by using an external USB hub. If you do so keep in mind you'll need to use a powered USB hub, since the Pi has very limited USB power output. Also, a powered hub is a necessity if you wish to hookup any high-power external devices, such as a hard drive, to the Pi. One final consideration regarding input devices - the Pi can also support wireless Bluetooth keyboards/mice, but it doesn't do so out of the box. You'll need to install some additional drivers. I'll go through the specifics of how to do this in a future post as well.

Case Closed
Now that we've covered most of the internal requirements for the Pi, it's time to wrap it all up - literally. You'll most likely want to purchase a case for your Pi to protect it from dust, static electricity and so forth (as well as make it easier to transport). While there are likely dozens upon dozens of case choices, in all kinds of imaginable colors, they are divided into two main categories - a molded case or a case kit. The former is typically a case that comes in two halves, where you place the Pi in the bottom of the case and snap on the top. The latter consists of a approximately 6-8 die cut pieces of plastic that you assemble into a case. The image below shows the case kit I built for my Pi. The choice of case type is entirely a user preference. My only recommendation is to make sure the case you choose allows proper ventilation, since the Pi doesn't have any type of heatsink or cooling fan.

Assemble it yourself case kit

Additional Information

You can find a list of tested Raspberry Pi hardware which is maintained by the Embedded Linux Wiki

In my next post we'll talk about installing and configuring the Raspbian OS. Until then, happy baking!

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