Qu’est-ce que la Raspberry Pi ? Que pouvez-vous faire avec ?

The Raspberry Pi is a miniature computer that is ideal for tinkering or home automation. Its controllable IO (input-output) pins make it very easy to read and control sensors and other hardware. Because of this and its low price, it is also a very popular way to get started in (hardware-related) programming for beginners, children and interested people.

raspberry-piMeanwhile the Raspberry Pi has been sold many millions of times and there is a ready-made solution for almost every application, or a way to achieve your dream project.

Why Raspberry Pi?

In view of various and much more powerful alternatives, the Raspberry Pi’s price and the resulting low financial barrier to entry are the main arguments in its favor. If you realize after the purchase that it was a mistake, you haven’t broken that much money and due to the great interest, you can quickly sell a Raspberry Pi including accessories again.
At the same time, the Raspberry Pi has the best software support compared to all other low-priced ARM computers. And there is a wide range of additional hardware and extensions available at low prices, which is hardly available or much more expensive with other ARM computers.

Alternatives to the Raspberry Pi

Many Raspberry Pi competitors are often more powerful and just as interesting in price. Unfortunately, the software support and documentation are significantly worse.

Banana Pi from Lemaker.org
Odroid from Hardkernel
Tinker Board from Asus
Galileo from Intel
Industrial PC

Raspberry Pi: Lots of possible applications

The Raspberry Pi has become the most popular small computer in recent years. It has undergone constant development and gained a large fan base. With its possibilities, it is equally interesting for educational purposes and specialists.

In contrast to microcontrollers, the single-board computer offers a full-fledged system on a small footprint, which can be quickly used for a variety of applications with little upgrading. Even the first model from 2012 offered the possibility of setting up your own projects without having to use a bulky PC or an expensive development kit.

The Pi family now also includes the compact Pi Zero, the Pi as a compute module and the most powerful Raspberry Pi 4 B to date.

raspberry-pi-appsIn the meantime, the Raspberry Pi has also found its way into industrial applications and is no longer just a hobbyist’s object. And what has been realized more or less professionally in the private sector until today, is now hardly manageable.

Not too long ago, there was a good selection of « pHats » for the Pi, modular-style modules where you can stack additional drivers, sensors, or displays on the GPIO strip without having to wire.

The Pi is particularly suitable for servers, in automation and for building computer-based devices, especially mobile solutions. It can be used for networking, bringing existing hardware into the IoT and building multimedia applications. And it is now also suitable as a workstation computer. This has led to many interesting projects where the Raspi is used, among other things, as a surveillance camera, smart USB stick, for stepper motor control, as the basis for info displays, NFC readers or in robotics.

And since there are always new people interested in the Raspberry Pi, it is worthwhile to have an overview, even if our selection can only cover a small part of the many possible applications and cannot be representative. So here’s an attempt at a selection, with the Pi as a desktop computer, network storage, wireless receiver, media server and as the basis for the Pi-Cam.

Use the Raspberry Pi as a desktop computer

You don’t need a desktop for integrated applications, and the first models weren’t really suitable for operation with a graphical attachment either. In the meantime, it is becoming more and more worthwhile to look at using a Pi as a Linux desktop computer.

Already with a Pi Zero you can work, from the Raspi 3 onwards X servers and a lightweight window system run smoothly. Meanwhile, Ubuntu Mate is also a popular installation, which should be run primarily on a Pi in the 4 version, where the Pi Foundation has mainly focused on performance improvements. Thus, since its release in mid-2019, the Raspberry Pi 4 Model B is considered a real desktop alternative if you want to build a power-saving surfing station, for example.

You can quickly find your way around on the Raspbian desktop. Chromium browser, VLC and Libre Office run, you can install a variety of applications known from development, office and multimedia, which you are also used to from a classic Debian or Ubuntu desktop.

It’s not surprising that nowadays there are fancy desktop sets available, where the Pi comes with case, keyboard, mouse and cabling not only color-coordinated.

Power saving NAS

The Pi feels at home in server applications, as it has everything you need for a slim HTTP, FTP or print server and is a cost-effective option to commercial solutions.

A good argument for the Pi in such 24/7 applications is its moderate power consumption. For example, many people would like to have a file server at home that is always available, but does not overburden their wallet with electricity bills. That’s where the Raspi comes in handy. And building your own network storage is not particularly difficult. To realize it, the Pi has to be connected to the local network and has to get shares for the accounts intended for access. If non-operating system computers are also intended, a Samba server can be set up.

If you don’t just want to browse the file system, you can use special software. A popular NAS distribution for the Pi is « OpenMediaVault ». It comes as a ready-made image for the SD card. After starting with the new image, you get to the web interface, where the first thing you do is set the administrator password and the attached drives. OpenMediaVault supports different user accounts, whose access rights can be set next. After that, you need to configure appropriate network protocols and services. Once everything is up and running, you have a really comfortable system at your disposal, which is a lot of fun to use on a daily basis.To get started, you can find everything you need to know at openmediavault.org.

With « ownCloud » it is possible for Pi friends to install their own cloud, similar to Dropbox or Google Drive, on their own web. Then you have a web interface available, with which you can realize uploads and downloads in the browser and manage various. The strengths of « ownCloud » include its user and group management and integrated viewers and editors for various file types.

To avoid overwriting your existing server installation with a new image like above, you can also use the well-known and feature-rich « rsync » for backup and synchronization purposes to the remote Raspi, where you can also work comfortably and script-based under Raspbian.

If you want to set up a storage with a Pi at home, you should have at least a 2 Raspi at hand and connect it to the router via LAN cable. The Raspberry Pi 4 B now also has two USB 3 ports, so access to a disk connected there is also sufficiently fast. Nowadays, the mass storage can also be one or more SSDs, which are not that expensive anymore.

And of course, with a simple hardware substructure, you forego various operational security, as is the case with a professional RAID. But that’s not what a home-made NAS is supposed to do. I still make various backups of valuable data and store them in a separate place.

The Pi as a universal wireless receiver

So that also special applications are not missing in our overview: How about using the Pi as a radio receiver via software-defined radio? With an SDR stick on the USB port of the Pi, « listening » on different bands becomes possible.

Such sticks with RTL chipset like from Gixa or Nooelec are known as DAB+ receivers, and they are also offered with Windows software for use on the PC, for example, to receive FM radio or digital TV terrestrially via antenna.

The possibility of tuning such chipsets in a wide frequency range also makes them suitable for controlling the communication of devices « transmitting » at 433 or 866 MHz, as is common in home automation or weather stations, or for receiving the secondary radar of passenger aircraft at 1090 MHz in order to evaluate their digital transponders. Last but not least, SDR can also be used to receive and decode data from certain weather satellites.

To realize this, all we need is a tuned or multiband antenna on the stick along with some software on the Pi. The rtl-sdr tools from osmocom run in the terminal. « rtl_test » and are used to check the installation. With « rtl_fm » you can receive FM radio. The tool is also used to record and store signals from higher frequency ranges. The resulting audio files can then be visualized. With « wxtoimg » to weather maps from NOAA satellites for example. How to do a prediction of the overflights is well described in various projects on the web.

For the reception of digital identifiers in air traffic there is the tool « dump1090 », which also runs in interactive mode and displays name, position data and speed of all reached transponders in a tabular overview in the terminal. If you want to extend the whole thing, you can use « rtl_tcp » to stream to an IP in the local network, and then you can evaluate various data with software like « Virtual Radar Server » on another computer in the home network. There you can see the moving symbols of the airplanes on a map in real time, and everything is graphically well prepared.

To make a very general evaluation of what is going on around you on the « air interface », graphical tools with « waterfall diagrams » are suitable. If you want to do more, you can have a look at the « gnuradio » framework. Whatever you want to receive, an interesting advantage of such a compact broadband receiver is that our Raspi and its peripherals can be placed outdoors near a larger antenna, protected from the weather. And connected via WLAN, the evaluation can be done on the work computer in the apartment. This avoids overlong antenna cables with high attenuation.

The Raspberry Pi as a Media center

For the Raspberry Pi user, the Libre-ELEC distribution offers an easy way to build a full-fledged media center. For some time now, an optimized version with Kodi 18.4 has been available, which can play H.265-encoded movies in 4K.

It’s worth using a Raspberry Pi 4 here, which can offer the best performance values due to its new hardware. And there are supposed to be further changes in Libre ELEC, after currently still having to work with an adapted 4.4 kernel, where HDR videos with increased contrast range cannot be displayed yet. But you can play them anyway.

To install the distribution, you can get the appropriate image from the web or you can work with the Libre-ELEC installation tool, where you can create your own SD card after selecting the Raspi version.

After starting the Pi, Kodi is available. The media center plays videos from data carriers or from the network, and you can watch Youtube movies. If you want to stream from Netflix or Amazon Prime, you need a corresponding subscription, of course. The website at https://libreelec.tv/ is a good place to look.

For an up-to-date media center, at least a Pi in the 3 version should be used, better still a Pi 4, which with its new SoC can play current movie material with the best performance. 1 GB of RAM is sufficient, the 4 GB version is not necessarily needed.

But you should provide enough cooling, because even if the Raspi 4 can use the built-in hardware decoder for HEVC content, it produces fundamentally more waste heat and is otherwise quite busy with video playback in the media center.

Working with the Pi-Cam

The Raspberry Pi had been available for a while when the longed-for camera was finally announced, and it’s been around since mid-2013 now. And since then, it has also undergone a revision. So if you want to develop applications with a camera, you no longer have to resort to USB webcams and use the Pi-Cam to connect to the special port on the board. This port is a bit narrower on the Pi Zero, and you can use appropriate ribbon cables.

Using the Pi and Pi-Cam, you can quickly build your own camera solutions, as an IP-Cam for example, where the Pi with camera acts as a webcam and regularly shoots pictures of the environment. These can then be made available to the public, as is common with weather cams, for example.

Or you can use your setup for surveillance at home, where you link the triggering of the recordings to a motion sensor. This is also how cameras for wildlife observation work, which are then set up in the field.

Using the NoIR-Cam, which is also available for the Pi as an infrared camera without an IR-cut filter, you can also take pictures at dusk. To collect enough light at night, the objects have to be illuminated with infrared light. For this purpose, too, there is now special camera hardware that works together with the Pi. During the day, the NoIR variant of the Pi-Cam again makes interesting effect shots possible. And with a few additional components, you can build your own camera, which you can then take with you on the go.

And that should be the end of our short overview. So there are many interesting possible applications for the Pi. Nowadays, you can draw from a range of comparable hardware, but the Raspberry Pi has the largest community and remains the first choice for explorers and developers alike…

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