Raspberry Pi Myths

“The Raspberry Pi is cheap.”

The RRP for a Raspberry Pi model B is £36. And yes, at a tenth of the cost of an iPad it’s within the range of most families, teenagers with a Saturday job and indeed schools. However, your £36 doesn’t get you a fully functioning, ready to program Pi. You need a few other bits and pieces if you want to do more than merely admire the circuitry. Unlike the iPad or indeed a laptop, Pis do not come with a fully integrated power supply, or a screen, or a keyboard, or a mouse. Not even a case! Without these things your Pi is just a circuit board. And these things will cost more than the Pi its-self.


"You can use spare stuff from home.” Now, to be fair, you might have a mini USB power supply lying around at home: it’s the same cable as many (non Apple) mobile phones use. And if you bought a TV or games console recently it will almost certainly have a HDMI connector and lead. Of course, if you are an iPhone user, have a telly or computer monitor that is more than a few years old you threw your USB keyboard and mouse away when you got a laptop it’s time to go shopping!

“Connecting up your Raspberry Pi is so easy that 3 year olds can do it.” It is easy enough to work out where each connector goes. However, remember that you do need the USB hub and a power supply. If you plug the mouse and keyboard into the two USB connectors on the Pi you may find that you get additional characters displayed when you type. Both the keyboard and mouse require power and the Pi doesn’t provide quite enough. So you do need to connect the powered hub to the Pi and the keyboard and mouse to the hub. If you are not sure about where to plug each cable into the Pi check out the quick start guide at: www.raspberrypi.org/quick-start-guide There’s also a really nice drag and drop activity to help you or your students identify each of the Pi’s connectors: www.ocr.org.uk/Images/127399-raspberry-pi-drag-drop-activity.swf Reading p14 to p18 of the Raspberry Pi User Guide or the more succinct instructions that come with the Maplin kit before you start plugging things in is also a good idea. Alternatively, you could or watch a three old do it. www.raspberrypi.org/archives/3504 (although it isn’t obvious if he is using a powered hub between his keyboard and mouse and the Pi.)

“You can’t break a Pi.” Rainbo Pibow Having connected all of the peripherals to your Pi you will have a naked circuit board amidst a serpent’s nest of cables and wires. And it will start to look a little vulnerable. One slosh from a mug of tea or contact with a conductive surface whilst powered up and the Pi will be toast! When people say you can’t break a Pi what they actually mean is that it doesn’t matter if you destroy the operating system because you can re-flash the SD card (assuming that you have access to a PC with an Internet connection!) However, the Pi board its-self is breakable. The I/O (input/ output) pins are exposed and so could get bent and of course if you get your wiring to and from these pins wrong you could short out the electronics!You do need to protect your Pi with a case. You can buy plastic cases either transparentor in an increasing array of colours. The Rainbow Pibow from www.adafruit.com at $19.95 is lovely. There are cheaper Punnet, plain and transparent cases available (especially on a well known online auction site). Or, you could make your own. Download a .pdf file of the net or rather Punnet(!) from www.raspberrypi.org/archives/1310 . Use the thickest card that will go through your printer without jamming it and use elastic bands to hold the box closed as this it makes accessing the Pi straight forward. Alternatively, print out the Punnet template and use it as a pattern for a ‘corriboard’ (corrugated plastic) case.

“It’s easy to install the operating system.” In most computer systems, the operating system (OS) is installed on the hard drive inside the computer. The Pi doesn’t have a hard drive so instead the OS is installed on a memory (SD) card. When the SD card is removed the Pi will not work and nothing will be seen on the monitor. You can either buy a pre-flashed SD card or install the OS to the card using a process known as ‘flashing’. To flash the card you will need a computer with a card reader and access to the Internet. You then need to download the OS from the Raspberry Pi Foundation website: www.raspberrypi.org/downloads You will also need a program running on your computer that will copy the OS image on to the card, for example, Win32 disk imager available from http://sourceforge.et/projects/win32diskimager You’ll need to decide which operating system to use. Raspbian ‘Wheezy’ is the OS of choice for most users. You can either download it as a single OS or download NOOBS (New Out Of the Box Software) which packages Wheezy with a number of other OSs and includes the ability to restore a corrupted OS from a partition on the card and to swap between different OSs.

“You can trash the software and it doesn’t matter” Yes, that is true. So long as you have access to the Internet and a machine with a card reader you can trash the operating system and rebuild it as many times as you like. Of course when you re-flash the memory card you’ll also overwrite any work you had saved to the card, so it’s probably a good idea to back up any programmes that you have written to a memory stick.

“It’s easy to use a Pi” Well, it not difficult, except that most of us are used to a Windows or Mac environment. There is a bit of a learning curve. If you are old enough to remember the days of command line prompts or are familiar with Linux you’ll adapt quickly. And as noted above, there are a number of different operating systems available for the Pi. So, if you have mastered Wheezy and you colleague is using RISC OS things will look rather different.

“The Pi is great for teaching programming” You can use the Pi to teach programming in the sense that it runs programming environments such as Scratch and Python. But you can run these on the PCs and laptops that you already have in school. If you want to teach children to create a game or control a screen turtle you probably already have the appropriate equipment and software. What’s more, you probably have enough of this stuff to allow pupils to work individually or in pairs.

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