All About The Raspberry Pi Computer

 

The Raspberry Pi is, simply put, an ultra-cheap complete computer that can run Linux, Fedora and Arch Linux. It was developed in the UK by the Raspberry Pi Foundation to get the youth of today to try their hand at engineering, bringing back reminiscences of the BBC Microcomputer system which was also designed with similar objectives in mind.

 

Fact: Raspberry Pi devices are sold as Model A and Model B. These are cultural references to the original models of the BBC Microcomputer.

Functioning on a credit-card sized board, it is a bare-bones PC to which you can connect a TV, keyboard and mouse, and on which you will be able to surf the Web, play Full-HD movies and do almost anything you would want to on a "normal PC" - provided you have the initiative and patience to make it work.

An electronics enthusiast or hobbyist or even a student can easily make use of this computer to build a lot of things: Linux Desktop, Gaming Device, Home Media Center, the list goes on. As more of these boards are shipped out, you can hope to see an even greater variety of uses and functions being executed by the Raspberry Pi computer. And since all the code is open source, it makes it so much easier on the pocket.

The Tech behind it

The Raspberry Pi will run Linux kernel-based operating systems like Debian GNU/Linux, Fedora, Arch Linux, etc. Iceweasel, Calligra Suite, and Python are planned to be bundled with the Raspberry Pi.

Perhaps the most important thing that differentiates the Raspberry Pi is its computing power. This 25$ Single Board Computer (SBC) has as much oomph as the original XBOX did--demos showed the Raspberry Pi handling Quake 3 at 1080p. Now Quake 3 is a game that made even my Intel P3 choke back in 2000.

The Raspberry Pi runs on a 700Mhz ARM11 CPU supported by a Broadcom VideoCore IV GPU. This SBC has a total of 256MB SDRAM which it generously shared with the GPU. The board is powered by a 5 volt microUSB or GPIO header and consumes between 500mA (2.5W) and 700mA (3.5W) depending on the models. The SoC that hosts the CPU, GPU, DSP and SDRAM is from Broadcom (BCM2835).

Another thing to note about the Raspberry Pi is that it 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 info for file time and date stamping. However, a real time clock (such as the DS1307) with battery backup can be easily added via the I2C interface.

Arduino vs Raspberry Pi

Starting from the radically different naming schemes--masculine Italian name vs sweet fruit pie--both these boards are significantly different in a lot of things. For one, the Arduino is an open source single board microcontroller while the Raspberry Pi is a single board computer. Ask any electronics enthusiast and he will tell you why it is always better to take the Arduino if this is your first time dabbling with electronics. On the other hand, if you have already dipped your toes in this field you could go ahead for the Raspberry Pi. Below you can find a chart that compares the two boards. It should help you make a good decision if you are new to this field.

Arduino	Raspberry Pi
Extremely easy to get working	Less easier to get working
A typical embedded system with easy-to-develop software	Complete computer running Linux
Support is available almost everywhere	Support is currently limited but should increase over time
More suitable for controlling hardware (robotics)	Features an extremely powerful GPU and can handle hi-def content
Umpteen different kits are available	Very few kits are available now
Low power consumption, capable of even microamps with very low clock	Comparatively higher power consumption that the Arduino
Verdict: While the Raspberry Pi is a great high performance option, the Arduino is a good general use board

Different Models

There are 2 models of Raspberry Pi currently featured at the foundation. The Model A is the base model that comes with a lower power profile and is less expensive.

The Model B is slightly more expensive and fully featured. It features an Ethernet port along with 2 USB ports in addition to all the features on Model A.

	Model A	Model B
Price	$25	$35
SoC	Broadcom BCM2835 (CPU, GPU, DSP, SDRAM)
CPU	700 Mhz ARM11 Family
GPU	Broadcom VideoCore IV 256MB(Shared)
Memory	256 MB SDRAM
USB 2.0 Ports	1	2
Video Output	Composite RCA, HDMI
Audio Output	3.5mm Jack, HDMI
Onboard Storage	SD/MMC/SDIO card slot
Network	None	10/100 Ethernet (RJ45)
Power Rating	500 mA(2.5W)	700mA (3.5W)

Model B was launched first because the Raspberry Pi foundation saw a larger demand for those models.

Launch Plan

The first launch of Model Bs is aimed at software and hardware enthusiasts, makers, teachers and others who want to build exciting things with the Raspberry Pi before the official educational launch, which will happen later in 2012.

They have done this phased launch to ensure that when the Raspberry Pi is launched for the educational market there will already be a community of experienced people in place who would provide support for the newbies. This will also ensure that more mature software will be available for children to use.

Knowing Your Linux System Via the Command Line

Every Linux user will tell you the same thing: know your computer. Mine always works not because there are no bugs, but because I know enough to identify their sources every time and correct them. And one of the best ways to monitor your system is through the command line. There are some great GUI for this, but the command line has the advantage of working on every computer, and it can easily be put into a script.

I propose to you five great commands for:

1. Knowing your kernel
2. Finding hidden processes
3. Listing running modules
4. Checking disk usage
5. Locating binaries and configuration files

1. Knowing your kernel

The kernel is the core of your Linux system. It is frequently updated, and knowing its version may be important for compatibility reasons. Certain programs may require a certain version in order to work properly. It may also be important for some peripherals and modules. As an example, my Ubuntu is based on the official kernel 3.0.0. So far, the latest version is 3.2.5.

To know exactly what kernel you are using, its version, and your computer architecture, use the command:

uname -mrs

With this example, we can clearly see that I am using the official kernel, version 3.0.0. The i686stands for my computer architecture. Here it means that I am using a 32-bit computer. On the other hand, x86_64 would have indicated a 64-bit architecture.

2. Finding hidden processes

To know what processes are currently running on your machine, most people would recommend the command “top“. Joshua wrote a very good article about it last year at Linux Running Too Slow? Here’s How to Find the Cause. Personally, I find this command very useful, and as Joshua explains, it can even be used to monitor the RAM usage.

However, I am sometimes too lazy to search in the list provided by “top“, and if I already know the name of the program running, I recommend the combination:

ps aux | grep [name of the program]

This will have the effect of listing all the current processes, even the smallest ones that will not be picked up immediately by “top“, and then filtering them according to your keywords.

This method will instantly give you the name of the user responsible for this process, the PID number, the CPU usage percentage, the memory usage, the name of the process, etc.

As a side note, if you don’t know how to kill a running process:

kill [PID number]

OR

killall [name of the process]

3. Listing running modules

Modules appeared in version 2.0 of the Linux kernel. They are very useful, and you can consider them as drivers that you can load and remove from the memory. As an example, if you are using a laptop, you probably have a WiFi card. The corresponding modules for that card are probably loaded automatically at start up. If you want to save some battery, you may want to stop the card when you are not using the Internet. Removing the corresponding driver from the memory will then give you a little bit more memory (and you will also be sure that your card is disabled).

But first you need to know which modules are currently running. The command for that is

lsmod

This command is simply the combination of “ls” for listing files in a directory and “mod ” for module (I know, what a surprise).

As a complement to your knowledge, you can add modules with the command

modprobe [name of the module]

and remove them via

rmmod [name of the module]

These two commands have to be launched by a super-user.

4. Checking disk usage

Keeping an eye on your system’s volumes can save you a lot of trouble. You may want to be sure that there is always enough room in /root, and remember to periodically clean your /tmp. For that purpose, there are two great commands:

lsblk

and

df -h

lsblk displays a tree representation of the partitions of your computer. It also gives you some useful information about the size of these partitions, their type, and their mountpoint.

However, even if lsblk is more visual, I still prefer to use df -h. The latter gives you more information about the remaining space, the size of the partitions, and the percentage of memory in use.

You may have noticed that the command df alone will give you the size in bytes, which might be very hard to interpret. The option -h stands for human readable and gives you the amount of data in gigabytes, megabytes, or whatever is the easiest for a human to understand.

5. Locating binaries and configuration files

One of the first things that confused me when I left Windows a few years ago was that the file system was completely different on Linux. There is no such thing as Program Files, or a single directory for all the configuration files. But it may be very useful to know where these binaries are. For that purpose, the command:

whereis

is among the best. Similarly to

whoami

which gives you the name of the current user, or

whatis

which explains a command quickly, whereis can locate binaries, manual entries, and various configuration files. Its syntax is also very simple:

whereis [name]

In the example above, I asked where Firefox was, and the command returned the location for its binary and various directories, as well as the manual page.

But one of the greatest strengths of whereis is its ability to locate standalone configuration files. Here is another example, where I was searching for rc configuration files:

Such options can become very useful, especially if you are not using Ubuntu but another distribution like Archlinux which requires a serious amount of time to edit these files.

Conclusion

With these commands in your pocket, you will be able to see a little more of what is going on in your system. If you still prefer to have a GUI for that, I would still recommend things like Baobab for the files and Gnome System Monitor in general.

 

Via MakeTechEasier.com

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