Raspberry Pi

2 November 2012

what it is

The Raspberry Pi (RΠ) is a picoformat (credit-card-sized) computer board designed by the Raspberry Pi Foundation of Caldecote, England (a suburb of Cambridge) as a tool for teaching basic computer science concepts to children. It became available this year (2012).

how it is built

The RΠ comes in two models, A and B. I bought the B model as it is the more powerful, has a network connector, and causes only ten dollars more.

Processor Broadcom BMC2835 (CPU/GPU/RAM), 700 MHz.
Memory 512 MiB.
Ports 2 USB 2.0, HDMI audio/video, 10/100 RJ45 Ethernet, SD card.
Offline Storage SD
Size 85.6 mm × 54 mm, the exact size of a credit card.
Weight 45 g

The SD card is for both the operating system and for off-line storage. Right now, the only real operating system for the RΠ is Raspian, a Debian Linux variant written especially for the RΠ. It is possible to run the RΠ from an external hard disk, but an SD card is necessary to boot it.

case

The case for my RΠ from Build-to-Spec came in the mail on Monday. As warned about, it took some effort to assemble (instructions here): The parts were small, including tiny nuts and light pipes; and the parts were covered with masking tape that had to be removed first.

Note: If you have problems working with tiny objects with your fingers, this case is not for you. Try the other cases at The Pi Hut or Adafruit.

The effort was worth it in the end, as I now have a fully functional computer based on the RΠ in a sleek black case.

I was hoping for a case that would mount to the back of my television set. Such cases are called VESA-mounted. Adafruit Industries shows a good-looking acrylic one, but it is still waiting for the product to be made. I am on its mailing list in case the case does show.

power supply

The RΠ needed a power supply, and it turns out that I did not have the appropriate parts for one at hand. I had to drive to Radio Shack and look for a power supply. I do not like Radio Shack: It has become more of a cellphone shop now; I already have a cellphone; and I am sure as hell not going to buy one that will chain me like a felon to AT&T or Verizon. Anyway, I had a tough time describing to the staff what I was looking for, so in the end I gave up and looked throughout the shop on my own. I did find a power block (5V, 3200mA) with a separate micro USB adapter plug for it.

I had thought that I already had the parts for a power supply; I did not know there was a difference between a mini USB plug (on cables for my camera and cellphone) and a micro USB plug (for the socket of the RΠ power port). If I had, I would have looked for the latter at Fry's while also looking for a HMDI/HMDI cable to plug the RΠ to my television set, which has two HMDI sockets.

sd card / operating system

I needed an SD card with an appropriate operating system for the RΠ to work from. The best thing to do is to order an SD card with the OS preinstalled, and to order an SD card with the most capacity. For OS read Raspian, RΠ-specific and based on Debian Linux. I bought this from The Pi Hut.

rπ itself

Now for the RΠ itself: I ordered mine from Allied Electronics, one of the few American companies that makes the RΠ available. I ordered the card in late July. I waited a long, long time before the card finally arrived in mid-October. Why the three month delay? From what I read, manufacturing problems, firstly, then a sudden decision to double the card's RAM 512 Mib. Allied sent me the card immediately after they received it. Oh, and no, I could not have gone elsewhere, because the other Web site offering the RΠ were as affected by the delay as Allied was.

first impressions

I have powered up the RΠ after plugging it into my television set. I had to cycle the power before a boot screen appeared. It was a rainbow square followed by the test sequence of Raspian booting up. On the first try, I was asked whether to start the visual interface, LXDE. LXDE is a very lightweight visual interface, required due to RΠ's limitations. Once LXDE came up, I tried out the various components made available.

Midori A lightweight but powerful Web browser based on the WebKit (Safari) engine.
Scratch An visual programming environment that uses blocks (code fragments) and sprites (animated figures) to teach programming skills. I used the copy of Scratch for a few minutes before it crashed. It was too much for RΠ to handle.
Squeak Scratch's foundation is basically Disney/Apple Smalltalk.
Python A series of Python games is available. I played one of the games available (a version of Snake), but could not get the Tetris clones to launch.
Editors The only real text editor available is Leafpad, LXDE's default editor. I will have to find a better Linux editor, or at least load vim on it.

Raspberry Π Links

Raspberry Pi: The official Web site.
RΠ FAQs: Most of your questions answered here.
RΠ Wiki: The RΠ wiki with more info for users.
Allied Electronics: I bought my RΠ here.
: RΠ accessories, incl. preloaded SD cards.
The Pi Hut Built-to-Spec: They make the case I use for my RΠ.
Adafruit Industries: Various RΠ components, including, one day, a mountable case.