We had an interesting computer. This is Raspberry Pi 2. What's so curious? For a start, the size. His size - the size of a credit card. And a very interesting price - $ 35. With delivery, of course, is a little more expensive, but still very low. What does he do and why is it needed? But first let's read the Chapter with the pathetic name of "unpacking".
UnpackingThe box is quite ordinary. In the box - the computer itself in an antistatic bag, manual and warranty papers. Nothing special. Smells, of course, not as products , but the smell is pleasant. What is in the kit? And complete but the box and papers is nothing. You need to buy a case (not everyone needs), cooling radiator (not everyone needs), peripheral devices (not all need), power supply with cable (must have), memory card micro SD (need all).
What's on the BoardThe Board uses a Broadcom BCM2836 processor. Inside it four cores ARMv7 Cortex-A7, graphics VideoCore IV dual-core that supports OpenGL ES 2.0, OpenVG and high profile decoding H. 264 1080p 30. Wow! This processor put in some top smartphones.
In addition to the CPU, the motherboard is placed a pulse power controller (in the previous version was linear, on transistor). Controller the periphery is closer to the USB ports and Ethernet. On the reverse side of the Board - chip RAM Elpida 1 GB. All grown-up, though very small. Raspberry Pi 2 first assembled at the factory Sony in England, but then moved part of production to China in connection with expansion of production volumes. Thus, there are two versions of the computer assembled in England and in China. No different, but the inscription on the Board. We got a Chinese build.
Also on Board are four USB 2.0, Ethernet 10/100 Mbit/s with the indicators of connectivity and data exchange, two LEDs (power and appeal to the media), the input power to the micro USB port, GPIO port, HDMI output, micro SD slot, composite RCA Jack (PAL and NTSC), audio Jack 3.5 mm port to connect the camera and the port to connect the display. These last two ports use flat cables, and connect to them only a special camera port and a touch display port. In General, bonavito on the Board a lot and it's a matter of respect.
OverclockingTo overclock the Raspberry Pi 2 not only possible but necessary. This procedure is encouraged by the manufacturer, and you will not deprive of the guarantee. Cool! Base frequency of the processor is 900 MHz. Staffing configuration utility proposes to charge overclock to 1 GHz, while the memory frequency and bus increases from 450 to 500 MHz. Still has Turbo mode, which is also included in the config (more specifically, is disabled, as by default it is enabled). It works as follows. You set maximum and minimum CPU frequency, and the frequency starts to be regulated dynamically depending on the load. Overheat protection is implemented on the built-in processor thermometer. You can specify in the config the temperature at which processor will also drop the frequency (default is 85 degrees Celsius). Upon reaching the threshold temperature the maximum frequency is rolled back to default until the CPU cools down. Beautiful solution.
Our machine runs at 1 GHz in Turbo mode. We tried higher frequencies. 1.1 GHz the problems begin with a graphical interface, and 1.2 GHz start crashing anyway. May need to be adjusted separately memory frequency, and bus voltage, but we do not have, 1 GHz, we are quite satisfied. In addition, we set two radiators. Copper on the CPU and aluminum on the controller periphery. The memory chip is practically not heated.
Memory cardThere are two ways. You can buy Raspberry branded card micro SD 8 GB with a picture of raspberries on Board and a preinstalled installer. And you can buy the card that you like at any store, and the installer download from the website Raspberry. The minimum amount of cards to 4 GB. Any maximum theoretically available, but the Raspberry writes that cards larger than 32 GB they stick in the machine have not tried it. We went through the second. Bought a micro SD card of 32GB with a sufficient speed (80 Mbps) and downloaded the installer from the manufacturer's website.
ConnectionIt's simple. You will need a keyboard, mouse, TV, or DVI display and the Internet in the form of Ethernet cable. To protect the body highly recommended. Well and the power supply. Voila, the computer is ready.
SoftwareIn fact, the configuration of the software is dictated by the hardware platform of the computer. This is a 32-bit ARM architecture. That is, if you thought that this machine can run .exe files from Windows or chopped in a PC game - forget. Raspberry is the Kingdom of Linux. Which is good, because it is a stable and secure system. The installer by default offers to choose Raspbian. This is the ARM version of Debian. And Raspbian is already present on the card together with the installer. In addition, you can still choose to Mate with Ubuntu, Snappy Ubuntu Core, Open Source Media Centre, Open Embedded Linux Entertainment Centre, PINET and RISC OS. Yet there is a version with a sort of Fedora called Pidora (mdaaa...). The installer will download from the Internet. In addition, there is a build of CentOS. We CentOS tried, but it's raw (at the time of this writing there is only an alpha version).
And there is even Windows 10, which also offers the installer. Only you can not think of something. This is not the Windows 10 that you can see in the computer. Will not hope. This is a special version for the Internet of Things. It allows you to run compatible with ARM software (what?) and it has no interface. No. This OS is controlled remotely. In General, the hell. But you can proudly say "compatible Raspberry Pi 2 with Windows 10" in the case of the Raspberry, but if you're Microsoft, you can say "Windows 10 works even on the Raspberry". The main thing is not to go into details.
We chose to install Raspbian, as it is the most stable, documented and has all imaginable packages to install. She has even built-in store packages and applications (free). The system installation takes about 15 minutes, you can pour yourself a Cup of tea during this time.
After installing the OS the system reboots, and then the default Petruska occurs in graphical mode. Machine loaded quickly. Works very fast, considering its size. No brakes. We had expected the recording to the micro SD card will be slow, but the developers machines understand the problem. The system by default uses the caching in RAM, while recording all the flies in there, and only then is written to the card. Therefore, it seems that everything just flies. Very reasonable. And REALLY everything works very quickly (everything is sitting in RAM) until you exceed the limits of the buffer in RAM. For example, when unpacking very large files the machine starts to slow down when writing to the card. But during normal operation you may not notice anything. All memory is dynamically allocated between the graphics interface, system and applications, and writing on the card takes place at the moments of minimum loads. But you can force to divide RAM into two parts. One for video and one for the operating system and applications. The graphics mode can be disabled altogether.
After you install Raspbian you will receive: a web browser, monitor the system, mail client, terminal, image viewer and pdf files and a complete set of office applications LibreOffice. Office applications are fast and compatible with all common document formats. Thus, the machine allows you to immediately begin work in the regime of a full office desktop. When you do this, you will not get any viruses and computer maintenance.
Real Time ClockAs I wrote in the computer real time clock no. So the machine at every boot requests time from servers on the network and the system pretends that the watch she has. And everything works fine. But you can buy a separate hardware block real-time clock that connects to the GPIO bus and eliminates the need of network requests. Such a module we bought and tell you how to install and enable.
Raspberry Pi 2 fall in love with. And the more the witch of the waste, the more you see how everything in it is intelligently and beautifully arranged. This is a very cheap and very small computer that is fast and effective. He almost does not get hot and not noisy. He knows how very much. Can work as an office computer as media center as the basis for the smart home, as a server, may be a torrent-rocking chair and transcode video. But about Windows and hard game to forget, it's not for Raspberry.
In General the Raspberry Pi 2 is a great little machine with big capabilities. Author: Dmitry Ivanov