lizconlan.com

Mmmm, Pi

Ok, what is it?

The Raspberry Pi (aka Pi, rPi or Rpi depending on who’s typing) is a small (really small - roughly the size of a credit card) computer on a single circuit board made by the Raspberry Pi Foundation, a registered charity in the UK founded with the aim of encouraging kids to play with computers, especially in schools.

It’s not a very powerful machine but it’s fanless (and therefore capable of silent running) and surprisingly flexible. It’s perfectly capable of running as a silent media centre with a suitable build of XBMC (geek-to-human translation: it’s really good at video). Oh and it’s cheap - demand is high so prices vary but it should set you back around £26 + shipping from an official supplier if you’re prepared to wait for stock. If you want it NOW be prepared to pay whatever people want to charge.

It says “Model B” - are there different models?

Kinda. The Pi available for public sale is the Model B. The Model A does less stuff and is even cheaper (assuming they’ve put it into production by now) with the intention that schools can afford to buy them. I seem to remember reading somewhere that the idea was that the proceeds of the sale of the Model B would help fund the Model A but I can’t find a link for that now so I might have dreamed it.

However there are now 2 versions of the Model B. The original had 256MB of RAM and was manufactured in China; the newer “rev2” board has 512MB of RAM and manufacture has been switched to South Wales. Hurrah!

Ok, what do I need to buy so that it’ll work on Christmas day?

Aside from the Pi itself, you will need:

A case

You can run it for testing purposes sitting on top of the cardboard box it came in but it’s not a great long term solution. Plus it’s a gift, right?

There are loads available ranging from the free Punnet template that you print onto card yourself - or onto paper and transfer it to card - then make the case yourself with scissors and glue to more expensive bespoke things made of wood.

The PiBow is a popular option, the PiCrust is cheap and the rubber band element seems suitable somehow and there’s loads of unbranded lasercut plastic and 3D printed options on eBay. Or of course you can always raid the kids’ Lego collection. Mmmm, Lego.

Bear in mind that open sided-cases allow more dust in but offer better ventilation if you’re worried about overheating.

An SD card

A camera card, basically - this is what the Pi will use as it’s main storage device - it’s where the operating system will go. SD and SDHC are both fine.

Learn from my mistake here - don’t worry too much about getting a large capacity one. Chances are you’ll either end up accessing your data files over the network or from a handy USB stick and the operating system will rattle around a vast amount of unused space. 8GB cards should be plenty, in fact 4GB is probably fine as well. There’s an official compatibility list, if you’re worried about whether a particular combination of brand and capacity will work.

If you’re buying for a geek-tinkerer rather than a child, the pre-installed cards are an unnecessary expense and may even spoil the fun. Amazon’s a good starting point.

A power supply

The people who sell the Pis will be more than happy to recommend one to you - although there is some criticism of the RS Components one for being too bulky to work with some cases. Haven’t had a problem with mine but maybe I’ve just been lucky.

All you need is a standard micro USB mains adaptor (also known as a phone charger) although you’ll need to examine the box - or failing that the writing on the gadget itself, usually between the mains pins - to make sure it’s got a high enough power output (stick with me - it’s not as bad as it sounds).

Many phone chargers are unsuitable for the task as they’re a lowly 200mA which won’t be enough to power up the Pi. The minimum recommended power output is 0.75A (also written as 750mA depending on which factory printed the label) so theoretically if you have a spare basic Kindle charger (they’re rated as 0.85A) lying around you should already have a wonderfully small and non-overheating solution ready to go.

However if you want to plug something more exciting that a generic keyboard and mouse into the USB sockets without resorting to the kind of USB hub that requires its own power supply, you might want something more powerful. Most power supplies sold specifically for the Pi come in at more like a 1.2A (1200mA) rating.

As ever, buyer beware - there’s currently a warning out for fake power supply units being shipped to the UK.

Cables

Power

If your chosen power supply doesn’t have one built in, you may need a USB to micro USB cable (as used by all modern mobile devices that aren’t manufactured by Apple). Look for one where the cable’s not too thing (cheap and nasty), where the micro USB end isn’t too bulky (might not fit into the Pi case - although if you’ve gone with an open-sided design, feel free to disregard this) and is a suitable length to run from the wall socket to the computer but isn’t too long as anything much over 2 metres can be problematic.

Display

A display cable (your geek may already have some spares - find a way of asking without arousing suspicion). Your exact requirements will vary depending on what sort of display device you’re planning on hooking your tiny computer up to. The simplest is connecting to a modern TV or a monitor with an HDMI socket (check the manual) in which case all you need is an HDMI to HDMI cable.

If you have a monitor that only supports DVI you’ll need http://www.amazon.co.uk/World-Data®-Premium-Quality-Plated/dp/B001NXPR74/. Or hedge your bets and invest in an HDMI to DVI adapter to go with the cable from the previous paragraph. This sort of setup might not get you the sound as well, in which case you’ll also need a 3.5mm to 3.5mm stereo lead (other examples are readily available).

If your slightly display equipment is of the slightly older variety (or you want to keep your HDMI TV for watching Christmas telly on) you’ll need to look to see if the 3.5mm to 3.5mm stereo lead (other examples are readily available) trick is going to work, otherwise you may need to resign yourself to getting (or pinching from the larger computer down the hall) a set of stereo speakers. I’ll leave you to search for that.

If your TV sports the good old AV IN connector (the red, yellow and white round sockets designed with a Camcorder in mind), you’ll require a Phono to Phono cable (other examples are readily available) - the yellow socket’s for video, plug it into that. Note disclaimer, above, about sound.

If you’re stuck with a SCART connector then something like this is your friend. Again, video to the yellow socket, you won’t get sound with this. Also if it’s a switched one, like the example here - make sure the switch is in the correct position, if in doubt try both!

Network

There’s no inbuilt wireless capability on the Pi so the easiest thing is to use the handy network socket (one of the things lacking on the for-education Model A, in case you were wondering). A geek household probably has several suitable network cables lying around somewhere (mine has a whole box full of the things - but then again I used to work for a company that allowed staff to buy them at cost price, or thereabouts, so maybe I’m a special case), but the key might be somewhere and they’re cheap enough if you’re not sure or don’t want to risk spending the entire Christmas break playing “I’m sure I left one here somewhere”. Expect to see words like “ethernet”, “lan”, “cat5”, “cat6” (and variants), “patch” and “RJ45” (if it says “RJ”something else, it won’t fit in the socket otherwise ignore it). Avoid the gold plating, ignore all “our cable’s better than their cable” claims, avoid anything that says “crossover” or “crosswired” - they’re for more ambitious projects and won’t work here - and buy the cheapest thing that’s long enough to do the job, it’s just to get the device working on the day.

A mouse and a keyboard

Good news - wireless mice seem to work, however wired mice will always work and cost very little. You may already have a spare mouse and keyboard to hand, if not - or if you’re not sure and don’t want to risk giving the game away by asking - get some cheapsters. The Tesco value brand ones work just fine.

Optional extra #1: a USB hub

Or more simply, a socket doubler (or quadrupler, or more). The Raspberry Pi only has 2 USB sockets and they’re quite close together so if you want to plug in a keyboard and a mouse and a USB stick (or a bulky USB stick and anything else), you’ll be wanting one of these. Prices start from under £5 (mine’s the cheapest that Tesco had to offer - it’s fine), don’t worry too much about brand names, do worry about easy returns just in case, do consider something with an optional external power supply (although this is far from essential, plus this is another thing your geek is likely to already have languishing in the back of a drawer somewhere).

Optional extra #2: a book

I like books. Books are cool. Plus it’s a good way to get your TV back so you don’t have to spend all of Christmas day watching someone try to remember how Linux works. There are a few books available, but I rather like the Pragmatic Programmers “Quick-Start Guide” which you can buy as an eBook direct from their site for $11 - your eBook will be DRM free, comes in a variety of formats (you get access to all of them and can download them whenever you like) and should be available within a couple of minutes of paying (all major credit cards + PayPal) plus you’ll get updates like the one they just issued to cover the 512MB version. Keep an eye out for discount codes!