Introduction the Raspberry Pi

1. 
   INTRODUCTION
   

The Raspberry Pi is a credit card sized single-board computer developed in the UK by the Raspberry Pi Foundation with the intention of stimulating the teaching of basic computer science in schools. The Raspberry Pi has a Broadcom BCM2835 system on a chip (SoC),which includes an ARM1176JZF-S 700MHz processor (The firmware includes a number of "Turbo" modes so that the user can try to attempt overclocking,up-to 1GHz, without affecting the warranty), VideoCore IV GPU,[10] and 256 megabytes of RAM. It does not include a built-in hard disk or solid-state drive, but uses an SD card for booting and long-term storage. The Foundation's goal is to offer two versions, priced at US$ 25 and US$ 35. The Foundation started accepting orders for the higher priced model on 29 February 2012.The Foundation provides Debian and Arch Linux ARM distributions for download. Also planned are tools for supporting Python as the main programming language, with support for BBC BASIC (using the "BrandyBasic" clone), C,and Perl.

An early alpha-test board in operation. Its layout is different from the beta and production boards.In 2006, early concepts of the Raspberry Pi were based on the Atmel ATmega644 microcontroller. Its schematics and PCB layout are available for public download.Foundation trustee Eben Upton assembled a group of teachers, academics and computer enthusiasts to devise a computer to inspire children. The computer is inspired by Acorn's BBC Micro of 1981.The first ARM prototype version of the computer was mounted in a package the same size as a USB memory stick. It had a USB port on one end and a HDMI port on the other.

The inventor of Raspberry Pi, a tiny low-cost computer which is about to hit the market, has no doubt that his Executive MBA programme at Cambridge Judge Business School helped turn his technical capability into developing a business.

There are two versions of the device which is the size of a credit card and priced at £16 and £22. When connected to a television and keyboard, it is capable of many desktop PC functions and also plays high-definition video.

Raspberry Pi is the brainchild of Dr Eben Upton, who says that as he embarked on his Executive MBA programme the idea was sound and the technical know-how was in place but missing were some of the ways of moving those forward.

“I had done a little software business in the past but certainly nothing in the volume manufacture of physical devices.

“The Executive MBA course helped me thinking about what we were doing in a more structured way rather than just muddling through. Thinking about how we develop the brand for the device, thinking about we work with partners and how we deal with some of the challenges that come with being ‘not for profit’ and therefore restricted in the ways in the ways you can raise capital at the same time as get a very large number of devices out.”

Dr Upton and colleagues at the Cambridge Computer Laboratory had been concerned at the declining figures for young people interested in computer science. Peaking in the mid-1990s at 500 people applying for 80 places each year to read computer science, by five years ago the number of applicants applying for the same number of places had halved.

That decline, says Dr Upton, was parallel to a decline in the skills and experience of the undergraduates taking the places. Many had tinkered with websites but few had touched programming.

This created a real problem because the University needs a good supply of potential candidates and does not want to spend the first year bringing people up to speed.

“Three years after it is a problem for the University it is a problem for industry because a decline in the number or skill set of applicants turns into decline in the number or skill set of graduates.”

Initially it was hoped that Raspberry Pi, by being aimed at children, would increase numbers looking to study computer science at university. Two additional markets have now emerged, one of which is the hacking or ‘maker’ community who already have some knowledge of the technology and want to build projects. The second market to emerge, says Dr Upton, was that of the developing world.

“We’ve had an enormous amount of interest particularly from the BRIC countries. A lot of interest from Brazil and Russia, less so from India and China, but a lot of interest from South America and sub-Saharan Africa.”

Dr Upton is a founder and trustee of the Raspberry Pi Foundation.

2.1Pre-launch

In August 2011, fifty Alpha boards were manufactured. These boards were functionally identical to the planned model B, but were physically larger to accommodate debug headers. Demonstrations of the board showed it running the LXDE desktop on Debian, Quake 3 at 1080p, and Full HD MPEG-4 video over HDMI.In October 2011, a development version of RISC OS 5 was being worked on and demonstrated in public.

Certificate of authenticity for an auctioned board

In December 2011, twenty-five model B Beta boards were assembled and tested from one hundred unpopulated PCBs.The component layout of the Beta boards was the same as on production boards. A single error was discovered in the board design where some pins on the CPU were not held high; it was fixed for the first production run. The Beta boards were demonstrated booting Linux, playing a 1080p movie trailer and the Rightware Samurai OpenGL ES benchmark.During the first week of 2012, the first 10 boards were put up for auction on eBay. One was bought anonymously and donated to the museum at The Centre for Computing History in Suffolk, England. The ten boards (with a total retail price of £220) together raised over £16,000,with the last to be auctioned, serial number No. 01, raising £3,500. In advance of the anticipated launch at the end of February 2012, the Foundation's servers struggled to cope with the load placed by watchers repeatedly refreshing their browsers.

The first batch of 10,000 boards was manufactured in Taiwan and China,[39][40] rather than in the UK. This is in part because import duty is payable on individual components but not on finished products. Chinese manufacturers also quoted a lead time of four weeks, compared to 12 weeks in the UK. Savings can be reinvested in the Foundation's research and development activities.Shipping delays for the first batch were announced in March 2012, as the result of installation of an incorrect Ethernet port. But the Foundation expects that manufacturing quantities of future batches can be increased with little difficulty if required.

"We have ensured we can get them [the Ethernet connectors with magnetics] in large numbers and Premier Farnell and RS Components [the two distributors] have been fantastic at helping to source components," Upton said.

Initial sales commenced 29 February 2012[44] at 06:00 UTC;. At the same time, it was announced that the Model A, originally to have had 128 MB of RAM, was to be upgraded to 256 MB before release. The Foundation's website also announced "Six years after the project's inception, we're nearly at the end of our first run of development –

Raspberry Pi 3 although it's just the beginning of the Raspberry Pi story." The two licensed stores selling them within the United Kingdom, Premier Farnell and RS Components, had their websites stalled by heavy web traffic immediately after the

launch. At one point the webmaster pleaded, "Guys – can you please stop hitting F5 on our website quite so often? You're bringing the server to its knees."Although as yet unconfirmed, reports suggest that there are over two million expressions of interest or pre-orders.[48] The official Raspberry Pi Twitter account reported that Premier Farnell sold out within a few minutes of the initial launch, while RS Components took over 100,000 pre orders on day one.[12] Manufacturers were reported in March 2012 to be taking a "healthy number" of pre-orders.[49]

On 16 April 2012 reports started to appear from the first buyers who had received their Raspberry Pi. As of 22 May 2012 over 20,000 units have been shipped.[52]On 16 July 2012 it was announced that 4000 units were being manufactured per day, allowing Raspberry Pis to be bought in bulk.[53][54] On September 5th the Raspberry Pi Foundation announced a second revision of the Model B Raspberry Pi On 6 September 2012 it was announced

that going forward the bulk of Raspberry Pi units would be manufactured in the UK, at Sony's manufacturing facility in Pencoed, Wales. The foundation estimates the plant will produce 30,000 units per month, and will create about 30 new jobs.

3.HARDWARE

Location on the PCB of connectors and major ICs

Block diagram of the Model-B

A Raspberry Pi system running X window server.

Initial sales are of the Model B, with plans to release the Model A in early 2013. Model A has one USB port and no Ethernet controller, and will cost less than the Model B with two USB ports and a 10/100 Ethernet controller.

Though the Model A doesn't have an 8P8C (RJ45) Ethernet port, it can connect to a network by using a user-supplied USB Ethernet or Wi-Fi adapter. There is in reality no difference between a model A with an external Ethernet adapter and a model B with one built in, because the Ethernet port of the model B is actually a built-in USB Ethernet adapter. As is typical of modern computers, generic USB keyboards and mice are compatible with the Raspberry Pi.

The Raspberry Pi does not come with a real-time clock, so an OS must use a network time server, or ask the user for time information at boot time to get access to time and date for file time and date stamping. However, a real-time clock (such as the DS1307) with battery backup can be added via the I²C interface.

On 20 April 2012 the schematics for the Model-A and Model-B were released by the Raspberry Pi Foundation.

Hardware accelerated video encoding became available on 24 August 2012 when it became known that the existing license also covered encoding. Previously it was thought that encoding would be added with the release of the announced camera module. However, for the time being, there is no stable software support for hardware H.264 encoding.^[

At the same time the Raspberry Pi Foundation released two additional codecs that can be bought separately, MPEG-2 and Microsoft's VC-1. Also it was announced that the Pi will support CEC, enabling it to be controlled with the television's remote control.

On 5 September 2012, a revision 2.0 board was announced, with a number of minor corrections and improvements.

On 15 October 2012, the Raspberry Pi foundation announced that all new Raspberry Pi model B's would be fitted with 512MB RAM chips instead of 256MB chips

• 
  Model A and Model B are cultural references^[86] to the original models of the British educational BBC Micro computer, developed by Acorn Computers, who originally developed the ARM processors (the architecture of the Raspberry Pi) and operating system RISC OS, which will also be able to be run on the Raspberry Pi (version 5.17).^[30]
  
• 
  On the older beta model B boards, 128 MB was allocated by default to the GPU, leaving 128 MB for the CPU.^[87] On the first 256 MB release model B (and Model A), three different splits were possible. The default split was 192 MB (CPU RAM), which should be sufficient for standalone 1080p video decoding, or for simple 3D, but probably not for both together. 224 MB was for Linux only, with just a 1080p framebuffer, and was likely to fail for any video or 3D. 128 MB was for heavy 3D, possibly also with video decoding (e.g. XBMC).^[88] Comparatively the Nokia 701 uses 128 MB for the Broadcom VideoCore IV.^[89] For the new model B with 512MB RAM initially there were new standard memory split files released( arm256_start.elf, arm384_start.elf, arm496_start.elf) for 256MB, 384MB and 496MB CPU RAM (and 256MB, 128MB and 16MB video RAM). But a week or so later the RPF released a new version of start.elf that could read a new entry in config.txt (gpu_mem=xx) and could dynamically assign an amount of RAM (from 16 to 256MB in 8MB steps) to the GPU, so the older method of memory splits became obsolete, and a single start.elf worked the same for 256 and 512 MB Pis.^[90]
  
• 
  Level 2 Cache is 128 kB, used primarily by the GPU, not the CPU.
  
• 
  The ARM11 is based on version 6 of the ARM architecture (ARMv6), which due to its age is no longer supported by several popular versions of Linux, including Ubuntu which dropped support for processors below ARMv7 in 2009.^[91]
  
• 
  The Raspberry Pi (model B) also contains a 15-pin MIPI camera interface (CSI) connector, which at the moment is unsupported, but the foundation is planning to release a camera module for it, sometime in the near future.^[92][93]
  
• 
  Support for raw LCD panels is available in hardware through the available DSI connector from the Mobile Industry Processor Interface (MIPI) Alliance.^[76] Software support is being planned.
  
• 
  Supported digital video resolutions are: 640 × 350 EGA; 640 × 480 VGA; 800 × 600 SVGA; 1024 × 768 XGA; 1280×720 720p HDTV; 1280 × 768 WXGA Variant; 1280 × 800 WXGA Variant; 1280 × 1024 SXGA; 1366 × 768 WXGA Variant; 1400 × 1050 SXGA+; 1600 × 1200 UXGA; 1680 × 1050 WXGA+; 1920 × 1080 1080p HDTV; 1920 × 1200 WUXGA.^] Also to be supported are the generation of 576i and 480i composite video signals for PAL-BGHID, PAL-M, PAL-N, NTSC and NTSC-J
  

• 
  Originally the on-board USB ports were designed for USB devices using one "unit load" (100 mA) of current. Devices using more than 100 mA were incompatible with the Raspberry Pi, and for them a self-powered USB hub was required. However, due to user feedback, the RPF, at the end of August 2012, decided to remove the USB polyfuses which largely caused this behaviour. However, the maximum current that can be delivered to a USB port on these modified boards is still limited by the capabilities of the power supply used, and the 1.1 A main polyfuse. Also a disadvantage of the current way the modification is done is that its no longer possible to hot-plug USB devices directly into the PI, when hotplugging is necessary it can be done in a hub.
  
• 
  Newer versions of the firmware contain the option to choose between five overclock ("turbo") presets that when turned on try to get the most performance out of the SoC without impairing the lifetime of the Pi. This is done by monitoring the core temperature of the chip, and the CPU load, and dynamically adjusting clock speeds and the core voltage. So when there is a low demand on the CPU, or it is getting too hot, the performance is throttled down, but if the CPU has much to do, and the chip's temperature allows it, performance is temporarily increased, with clock speeds up to 1 GHz, depending on the individual board, and on which of the "turbo" settings is used. The five settings are:
  
  • 
    "None"; 700 MHz ARM, 250 MHz core, 400 MHz SDRAM, 0 overvolt,
    
  • 
    "Modest"; 800 MHz ARM, 250 MHz core, 400 MHz SDRAM, 0 overvolt,
    
  • 
    "Medium" 900 MHz ARM, 250 MHz core, 450 MHz SDRAM, 2 overvolt,
    
  • 
    "High"; 950 MHz ARM, 250 MHz core, 450 MHz SDRAM, 6 overvolt,
    
  • 
    "Turbo"; 1000 MHz ARM, 500 MHz core, 600 MHz SDRAM, 6 overvolt^[4][96]
    

Visual diagram of API connections

The Raspberry Pi uses Linux kernel-based operating systems. Raspbian, a Debian-based free operating system optimized for the Raspberry Pi hardware, is the current recommended system, released in July 2012.^[97]

The GPU hardware is accessed via a firmware image which is loaded into the GPU at boot time from the SD-card. The firmware image is known as the binary blob, while the associated Linux drivers are closed source.^[98] Application software use calls to closed source run-time libraries which in turn calls an open source driver inside the Linux kernel. The API of the kernel driver is specific for these closed libraries. Video applications use OpenMAX, 3D applications use OpenGL ES and 2D applications use OpenVG which both in turn use EGL. OpenMAX and EGL use the open source kernel driver in turn.^[99]

On 19 February 2012, the Raspberry Pi Foundation released its first proof of concept SD card image that could be loaded onto an SD card to produce a preliminary operating system. The image was based upon Debian 6.0 (Squeeze), with the LXDE desktop and the Midori browser, plus various programming tools. The image also runs on QEMU allowing the Raspberry Pi to be emulated on various other platforms.^[100]

4.2 System software

On 8 March 2012 The Raspberry Pi Foundation released Raspberry Pi Fedora Remix, at the time its recommended Linux distribution,which was developed at Seneca College in Canada. The Foundation intends to create an App Store website for people to exchange programs

In addition, work is being done on system-specific light Linux distributions such as IPFire, OpenELEC, Raspbmc and the XBMC open source digital media center.

Trustee Eben Upton publicly approached the RISC OS Open community in July 2011 to enquire about assistance with a potential port. Adrian Lees at Broadcom has since worked on the port, with his work being cited in a discussion regarding the graphics drivers.

On 24 October 2012 the Raspberry Pi Foundation announced that "all of the VideoCore driver code which runs on the ARM" had been released as free software under a BSD-style license, making it "the first ARM-based multimedia SoC with fully-functional, vendor-provided (as opposed to partial, reverse engineered) fully open-source drivers", although this claim has not been universally accepted.

This is a list of operating systems running, ported or in the process of being ported to Raspberry Pi.

• 
  Full OS:
  
  • 
    AROS
    
  • 
    Haiku^[118]
    
  • 
    Linux
    
    • 
      Android
      
      • 
        Android 4.0 (Ice Cream Sandwich)
        
    • 
      Arch Linux ARM
      
    • 
      R_Pi Bodhi Linux^[119]
      
    • 
      Debian Squeeze
      
    • 
      Firefox OS
      
    • 
      Gentoo Linux^[120]
      
    • 
      Google Chrome OS
      
      • 
        Chromium OS
        
    • 
      PiBang Linux^[121]
      
    • 
      Raspberry Pi Fedora Remix
      
    • 
      Raspbian^[122] (Debian Wheezy port with faster floating point support)
      

• 
  Slackware ARM (formerly ARMedslack)
  
• 
  QtonPi a cross-platform application framework based Linux distribution based on the Qt framework
  
• 
  WebOS
  
  • 
    Open webOS^[123]
    
• 
  Plan 9 from Bell Labs^[124][125]
  
• 
  RISC OS
  
• 
  Unix
  
  • 
    FreeBSD^[126]
    
  • 
    NetBSD^[127][128]
    

• 
  Multi-purpose light distributions:
  
  • 
    Moebius, a light ARM HF distribution based on Debian. It uses Raspbian repository, but it fits in a 1 GB SD card. It has just minimal services and its memory usage is optimized to keep a small footprint.
    
  • 
    Squeezed Arm Puppy, a version of Puppy Linux (Puppi) for the ARMv6 (sap6) specifically for the Raspberry Pi.^[129]
    

• 
  Single-purpose light distributions:
  
  • 
    IPFire
    
  • 
    OpenELEC
    
  • 
    Raspbmc
    
  • 
    XBMC
    
  • 
    XBian
    

• 
  Asterisk (PBX), the Open source PBX can be used via IP phones or Wi-Fi softphones
  
• 
  BOINC client; however very few BOINC projects deliver ARM compatible client software packages...
  
• 
  minidlna, a DLNA compatible home LAN multimedia server
  
• 
  Firefly Media Server (new RPiForked-Daapd), an iTunes compatible Open source
  

Top of Form

Bottom of Form


There have been reports in the technology press about how much extra cost there is to owning the Raspberry Pi. Whilst these may be correct in stating how much they paid for accessories these do not reflect the realities of the pupils / students that the Raspberry Pi is intended for who will have different hardware available and be a lot more resourceful than the journalists that have paid over the odds for a simple cable compared to much cheaper alternatives.

5.1 Power supplies

The power supply is a an essential item to use the Raspberry Pi. The power supply for the Raspberry Pi is a standard micro-usb charger. This is the de-facto charger for most mobile phones as well as other electronic devices. I have dozens of USB adapters in the house that are suitable. This includes laptop power supplies, my Android (HTC) phone charger, Asus tablet charger, USB hub and more. The minimum requirement is that the supply must be capable of at least 700mA.

There are several chargers on Amazon starting from about £2. The details are a little sketchy for many of these devices, so I've used one that I've actually tried - which is a standard Nokia phone charger. These are available from about £6.

5.2 SD memory card

The operating system is stored onto an SD memory card. The minimum size for the SD card is 2GB. Whilst most will have an SD card for a digital camera, most will buy a new SD card dedicated for use on the Raspberry Pi. A 4GB SD card is available for about £3.50. We can use branded SD cards ( data is worth more than the small difference of buying unbranded cards), but I tried the standard speed SD card and some faster speed SD cards. There was not any any performance improvement with the more expensive card. My testing was very basic and only limited in scope. You may find that if using the SD card intensively that there is a difference, but boot times and normal performance did not appear to differ between different speed cards.

The operating system needs to be transferred to an SD card. This can be done on any computer with an SD card reader. Most fairly recent computers now include this as standard. If not then the example shown costs about £3.50, although can be bought from less.

Most standard USB keyboards and mice will work with the RPi. Wireless keyboard/mice

should also function, and only require a single USB port for an RF dongle. In order to use a

Bluetooth keyboard or mouse you would need to use a Bluetooth dongle, which again uses a

single port.

Remember that the Model A has a single USB port and the Model B only has two (typically akeyboard and mouse will use a USB port each).

The Raspberry Pi is designed to be connected to a TV, which most people have at home already. I have not included the cost of a TV in either of the prices, but one can be purchased second hand for as little as £20 from BHF Furniture and Electrical stores.

The best way to connect to a TV is via a HDMI port. This is only available on recent digital TVs, although those are quite common in homes and students bedrooms today - The cable shown on the right costs about £3.50.

To use an analogue TV then the composite cable is required. This goes from the yellow video out socket on the Raspberry Pi to the TV. Many TVs have composite sockets which the cable can be connected to directly, but for those with SCART only then a SCART adapter is required for the TV end. The SCART adapters typically cost about £2, or can often be found cheaper at the one pound stores (I've not included that in the costs below as it is not normally required).

The composite cable (consisting of 3 pairs of wires for the video, audio left and audio right) costs between about £2 and £5. I've used £3.50 for this example.

To get the audio through the TV as well as the video then a 3.5mm to phono adapter is required to connect between the audio out on the Raspberry Pi and the red and white leads on the component cable. These are normally available for £1 or less. The one I use came from a computer fair several years ago.

Full cost: £4.50

Raspberry Pi will be connected to a TV, but if you do have a digital monitor that could be used instead. Whilst some monitors have a HDMI port, most will have a DVI connection instead. Contrary to some comments you do not need to convert from HDMI to DVI as they are in fact the same electrical signals, but you will need a suitable cable. These cost from about £2.50 each.

Clearly these cost much less than the Raspberry Pi .

One difference between HDMI and DVI is that DVI does not include audio, so external speakers or similar are required if you want to use audio.

Although using DVI to a monitor is preferable many cheaper monitors still have only analogue VGA inputs. In this case it is not possible to connect directly to the monitor as the signal needs to be converted from a digital signal to an analogue signal. Whilst these converters may have been expensive when HDMI was new they are now available for about £15. Please ensure that the one you buy is listed as a converter, active converter or "with chip", and is not just a cable that changes the connector type as some cheaper cables may be. It won't work if it doesn't have the required electronic chip to convert the signal from HDMI to VGA. I bought the one shown here from Amazon marketplace which works fine.

This does not support audio from the HDMI port, so external speakers will also be required to connect to the onboard 3.5mm adapter.

5.6 Not included

The items listed above are the ones needed to make the Raspberry Pi work, but there are some other accessories that are useful.

The Raspberry Pi has only two USB ports that are usually connected to a keyboard and mouse. If you wish to connect anything else then you will instead need to connect to a powered USB hub. This is also a good idea when using any USB device that requires more than a minimal amount of power from the USB port. The hub can also be used to power the Raspberry Pi requiring only a USB to MicroUSB cable instead of the power supply mentioned earlier.

An Ethernet cable is required to connect the Raspberry Pi to a router. These are often supplied with routers so you may have one spare already or can be purchased cheaply. Either CAT-5e or CAT-6 cables can be used. The port is limited to 100Mbps so there is no benefit to using the (usually) more expensive CAT-6 cables.

The Raspberry Pi is supplied as a bare board without any case. I have not had any problems from normal handling of the Pi and it's fine to leave as it is. If however you would like to protect it with a case then there are several alternatives available from commercial 3rd party cases to make your own. I have created my own Raspberry Pi case (The Raspberry Pirate Chest) which cost just £3.50, plus some paint and glue.

Whilst not required if you are using a TV, external speakers may be required for audio when using a monitor. Any standard audio speaker with a 3.5mm plug should work OK.

USB flash drives or external USB disk drives can be connected to the Raspberry Pi to increase the amount of storage. These are not necessary for learning to program, but could be useful if you wanted to create a Media player or similar.

There are lots of other accessories available (either USB or some for direct connection to the connectors on the Raspberry Pi), that can add additional functionality, but are not required.

1. 
   Plug in your keyboard and mouse
   
2. 
   Insert your SD card
   
3. 
   Attach any other hardware
   
4. 
   Switch on your broadband router, (This step is optional.)
   
5. 
   Connect your Raspi to a screen using either the HDMI or the composite output.
   
6. 
   Plug in your 5V Micro USB charger and connect it to the Micro USB slot on the Raspi
   

• 
  Low cost
  
• 
  Linux box- freeware
  
• 
  No case-infrastructure make aware on hardware components
  
• 
  Increases creative thinking in users as they can do experiments
  
• 
  Users can develop applications based on their field and interest.
  
• 
  Inexpensive way for students for studying computer science
  
• 
  Students can carry Raspi like books..
  
• 
  It is a turning point in low cost computer applications!
  

• 
  User friendly but must be more aware of limitations
  

• 
  No case-insecure if it will come into contact with conductive metal,or liquids….
  

• 
  cannot install programs which need more resources.
  
• 
  Immature software, underwhelming CPU.
  

• 
  No windows os .
  

The Raspberry Pi is a small computer. It's about the same length and width as a credit card and costs only $32. It has been designed as a educational computer for school children to learn to program, but is also hugely popular due to it's small size and amazing low cost.Human knowledge is developing stage by stage .Every inventions will create more new questions and inventions. This will continue. Benefits of such developments are distributed socially. Hardware knowledge and software knowledge are interrelated .Raspi helps to increase hardware knowledge and software applications related to that.Raspi motivates users to develop wide range of applications in every sector. This is not only a little pc!!