The Raspberry Pi is a single-board computer developed in the United Kingdom by the Raspberry Pi Foundation. The presentation to the public took place on February 29, 2012.
The card was designed to accommodate operating systems based on the Linux kernel or RISC OS. It is assembled in Wales, in the Sony UK Technology Center. A specially dedicated operating system has been designed, called Raspbian.
The first designs of the Raspberry Pi, in 2006, were based on the Atmel ATmega644 microcontroller. The printed circuit diagrams and layout of this prototype are available for free download and for assembly by users. Eben Upton of Broadcom formed a group of teachers, academics and computer enthusiasts to conceive an object capable of encouraging children, providing them with know-how and inspiration.
On February 19, 2012, the Raspberry Pi Foundation made available a proof of concept of a disk image loadable on SD Card to produce a preliminary operating system. The image was based on Debian 6.0 (Squeeze), with LXDE as the desktop environment and Midori as the browser and contained various programming tools. The image could also run on the QEMU emulator, allowing you to emulate the Raspberry Pi on various other platforms. In July 2012 the Raspberry Pi Foundation promoted the development of a particular version of Raspbian called RetroPie dedicated to retro gaming since it included several emulators of various consoles and home computers.
The foundation released in 2016 an operating system based on Fedora and a version of Arch Linux. In the same year, a Debian-based operating system was produced which was later called Raspbian.
The project is based on a Broadcom-made system-on-a-chip (BCM2835, or BCM2836 for the Raspberry Pi 2, or BCM2837 for Raspberry Pi 3), which incorporates an ARM processor, a VideoCore IV GPU, and 256 or 512 Megabyte or 1 Gigabyte of memory. The project does not include hard drives or solid-state drives, relying instead on an SD card for boot and for non-volatile memory.
For each revision, several versions have been produced:
- Model A
- Model A +
- Model B
- Model B +
- Zero model
- Zero W model
Model A and Model B are both cultural references to the British computers BBC Micro, original models developed by Acorn Computers, which were also responsible for the original development of the ARM processors (the architecture of the Raspberry Pi) and of the RISC OS operating system, which runs on these hardware platforms.
Although Models A and A + do not have an Ethernet port with an RJ45 interface, they can still access a network through the USB port through autonomously powered Ethernet or Wi-Fi adapters. Similar to modern computers, the Raspberry Pi is compatible with generic keyboards and mice connected to the USB port.
Model B is equipped with two USB ports and a 10/100 Ethernet controller and costs USD 35. As of October 15, 2012, the Model B mounts 512 Megabytes of RAM. A conceptual update of the Model B called Model B + was later put on sale, equipped with 512 Megabytes of RAM, 4 USB ports, and a power system redesigned from scratch. Model B + also costs $ 35. However, it does not have a real-time clock, so the operating system must use a network time server or ask the user for the time at bootstrap to have access to the date and time for the time stamp. However, it is easy to add a model (like the DS1307) with a backup battery, through the interface I2C.
The Raspberry Pi Foundation officially releases GNU / Linux based operating systems, including NOOBS and Raspbian, both based on Debian GNU / Linux. NOOBS contains a simplified installer while Raspbian offers a text installation procedure like Debian. There are distributions for the use of the Raspberry Pi as Kodi-based Media Center: OpenELEC, XBian, and OSMC.
Network monitoring software Overlook Fing was brought to the Raspberry Pi platform making it possible to install low-cost monitoring sentries in remote networks.
The open-source Aseba software for simple and efficient robot programming is available on Raspberry Pi. By using the Raspberry PI in conjunction with Aseba and the Thymio II robot, it is possible to create a real robotics teaching laboratory at really low costs. The Thymio II robot was developed within the NCCR Robotics program by the collaboration between the Ecole Polytechnique Fédérale de Lausanne (EPFL]) and the Ecole Cantonale d’Art de Lausanne.
Mojang and 4J Studios have already developed a version of Minecraft (0.1.1) for this platform.
Raspberry Pi / Pi revision 2
The first ARM-based prototype version was mounted on a card about the size of a USB key, with a USB port on one side and an HDMI port on the other.
Fifty alpha versions of the card were released in August 2011. These cards were functionally identical to the designed model B. The test versions of the card showed the LXDE desktop environment on Debian, Quake 3 at 1080p, and Full HD H.264 video on HDMI.
In October 2011, the logo was chosen from a number of proposals from the members of the community: after drawing up a rose containing six proposals, the final choice took several days. The design chosen was based on a buckyball. During the same month, work was underway on a development version of RISC OS, which was the subject of a public demonstration.
In December 2011, a hundred beta versions of the B Beta model were assembled and tested. The layout of the components used in the beta version is the same as that intended for production, except for an error in routing in the printed circuit board project discovered and resolved before starting production. The Beta cards had a public demonstration with boot from Linux: on that occasion, it was proposed the reproduction of a trailer at 1080p and the execution of a demo of the OpenGL ES Samurai benchmark produced by the Finnish Rightware (ex Futuremark).
The first 10 cards were auctioned on eBay in the first weeks of 2012. One was bought by an anonymous and donated to the English museum The Center for Computing History, located in Suffolk. The ten cards, the total cost of which was £ 220, raised more than £ 16,000 in total, with the award of the last auctioned item, labeled with serial number # 01, at a price of £ 3,500.
The first batch of 10,000 cards was produced in Taiwan and China, rather than in the UK. Because of the customs policies, since customs duties are due on the individual components but not on the finished products, it is not convenient to import the components from the East for subsequent assembly in the West. In addition, Chinese manufacturers had estimated waiting times for order execution in 4 weeks, compared to the 12 weeks required in the UK. The savings obtained from the relocation can be reinvested in the foundation’s research and development activities.
The sale of the Raspberry Pi model B officially started on Wednesday 29 February 2012 at 06:00 GMT: the foundation did not conduct a sale on its own, but relied on two large distributors specialized in the electronic field, Farnell and RS Components, able to guarantee a more widespread worldwide distribution, thanks to the branches and branches in various countries around the globe.
A revision of the PCB was announced in September 2012. The main new features of the board are the ability to receive power via a powered USB hub and the availability of debugging via JTAG; as minor novelties, there is the correction of a connection defect via HDMI (leaving the Raspberry Pi not powered on an HDMI chain, problems could arise in the use of the Consumer Electronics Control functionality for the other devices), the reset circuit has been renewed, an additional expansion connector and mounting holes have been added and screen printing corrections have been made. There are also changes to the GPIO and I2C channels. The name “Raspberry 2.0”, which appeared on some sites, is wrong: the changes made only involve the correction of some design details, nothing that justifies the increase in the version number from 1.0 to 2.0, as also reported on the manufacturer’s website. The board has simply undergone a revision to the circuit which fixes minor problems: it is the printed circuit board which is in its second version, not the board as a whole which maintains the same identical components.
Raspberry Pi 2
Available from February 2015, 900 MHz quad-core CPU, increases the performance by about 4 times for the CPU and improves the hardware characteristics, making it more versatile.
Raspberry Pi 3
On February 29, 2016, the Raspberry Pi 3 was launched which presents some new features: it is the first model with a 1.2 GHz 64-bit ARM Cortex A53 quad-core CPU and well twice the L2 cache (512 KiB on the Pi 3 against the 256 of the Pi 2), which is flanked by 1 GB of LPDDR2 RAM (900 MHz).
The new model also integrates Bluetooth (4.1 and Low Energy) and Wi-Fi 2.4 GHz 802.11n modules.
Raspberry Pi 3 B +
The Raspberry Pi 3 Model B + was released on the market in March 2018 and stands out from the rest because it is the first to mount a CPU with a metal top cover. The main changes concern:
- Change of the Ethernet connection, which goes from 10/100 Mbit to Gigabit, even if the maximum reachable speed is however limited to about 300Mbit;
- Addition of 5 GHz Wi-Fi and improvement of the general performance of wireless networks;
- Ability to power the Raspberry via PoE (with a special additional HAT);
- CPU clock frequency raised to 1.4 GHz and thermal performance improvement;
- Bluetooth V4.2.
Raspberry Pi 4 B
The Raspberry Pi 4 Model B, released on the market in June 2019, features a 1.5 GHz quad-core Broadcom BCM2711 and offers many new features compared to its predecessors:
- RAM LPDDR4 (with versions of 1, 2 and 4 gigabytes of RAM);
- Two micro HDMI ports with 4K support;
- 802.11ac dual-band WiFi module;
- Bluetooth V5.0;
- Two USB 3 ports + two USB 2 ports;
- Power supply via the new USB-C connector.
Raspberry Pi Zero (v1.3)
The first SBC to be marketed for USD 5. It has no network connections.
Raspberry Pi Zero W
Placed on the market on February 28, 2017, the “Raspberry Pi Zero W” is equipped with 512 megabytes of RAM, and 802.11n WiFi module and Bluetooth 4.1
Since the project aims to reduce costs, hardware decoding of some multimedia formats is not supported by default, because they require a specific license.
The device can reproduce the H.264 format through hardware decoding, while to play the MPEG-2 and VC-1 formats it is necessary to enable hardware decoding, by purchasing the relevant license. This allows you to keep the price low, and not make the user pay those licenses that he doesn’t need.
Raspberry Pi mod. B revision 1 was rated by PCMag magazine 4 out of 5 stars, while the B revision 2 models were rated by Board-DB.org 4.1 out of 5 stars.