Top 8 ambitious projects for Raspberry Pi

The possibilities of Raspberry Pi extend far beyond what might seem. This small computer gives us the chance to undertake ambitious projects, expand our knowledge of many technologies, and acquire new skills – it's not worth limiting ourselves!

In articles discussing typical applications of Raspberry Pi, the same projects are always mentioned – a media player, a simple robot, learning programming, etc. But what ideas should a more advanced builder consider? Which offer the opportunity to learn in unusual fields, practical use of image analysis, communication with electronic modules, connecting sensors...? In this article, we describe 8 proposals for interesting constructions for DIY enthusiasts, students, and other ambitious users.

In this article, we cover topics such as:

• How to send a probe near space?
• Advanced robotics with Raspberry Pi
• Nature and surroundings observations
• Automated radio and television recording
• Listening to amateur and satellite signals
• Ambitious version of a retro game emulator
• Raspberry Pi in service of drivers
• Automation in the garden and meteorological observations

To the sky and towards space

The fact that our project will be amateur does not mean it has to lack far-reaching aspirations. The small computer allows us to enter fields that at the beginning of the century would have been accessible only to the most determined enthusiasts. So let's start our review with the most ambitious inspirations.

Earth seen from a stratospheric probe.

Weather balloon

On our planet, we live in the layer of the atmosphere called the troposphere. Roughly at its upper edge, about 8000m above the surface, passenger planes move. Above is the stratosphere, and the oxygen thinning is sufficient for the sky to lose its bluish hue, and the black abyss of space becomes visible. Reaching space itself is beyond the capabilities of a home project, as it would require sending a probe to a height of over 100km (of course, this is a conventional boundary). Nevertheless, literally nothing stands in the way of handcrafting a device that will soar above mountains, clouds, the ozone layer, and allow us to look at our planet from a completely different perspective. However, it is worth paying attention to local aviation regulations in advance to avoid potential problems arising from violations of applicable regulations.

Honestly, we must admit that we start our list of proposals with probably the most expensive project. A weather balloon will be used to "power" our project. The shell can be purchased from many specialized sellers. The largest can lift a load weighing over 1kg, but in the case of a miniature device built on the basis of Raspberry Pi (especially in its compact version, i.e., Zero, we can opt for a much smaller model. The budget will also need to include related costs, such as helium, which will fill the balloon, and a parachute, which will be used to secure the descent of the probe (regulations require this element to be included in our mission!). With a bit of luck, we will recover the parachute intact. It is usually clipped between the balloon and the payload. At a certain height, the pressure drop will cause the balloon to expand until it bursts – the payload will begin to fall rapidly, and the airspeed will automatically lead to the canopy opening and cushioning the fall. Here it is worth noting that the mission budget should include expenses for our journey – as it may happen that to recover the probe, we will have to travel even several hours. Here, let's emphasize that the device's casing must be highly mechanically resistant and sealed, in case of landing on hard or wet ground.

How we equip the Raspberry Pi, which will be the heart of our probe, depends on the function the device is to perform – but having all the computer's capabilities at our disposal, it is worth approaching the project ambitiously. Almost certainly, we will want to equip the payload with cameras – Raspberry Pi can simultaneously record images from several sources, e.g., one lens directed downward, another at the horizon. A third can take pictures of an object placed on a boom (e.g., a mascot or another trinket), which we will keep as a souvenir along with a photo against the backdrop of space. Other elements of the probe, of course, include sensors (temperature, pressure/altitude), which will record conditions during the flight. A certain challenge would be to place a transmitter in the payload allowing remote communication with our vehicle, although it will be difficult to find a transmission module with optimal strength and bandwidth. The last element of the project is a GPS receiver and GSM module (or rather LTE), which will inform us of its location after the probe lands. Such a locator can be purchased as a ready-made product, but it would be a shame to waste such an opportunity to learn about geolocation and data transmission via the cellular network.

Terran rover

First, let's focus on the chassis construction, the method of driving our robot, and its target functionality. The construction must be resistant to adverse weather conditions and allow the vehicle to move in difficult terrain conditions. In addition, the target functionality of the machine must be considered – it can be equipped with a gripper arm, a rotating camera head, sensors, etc. If we would like to participate in competitions in the future, it is worth reading the regulations of the given competition in detail: the organizers precisely define the tasks that will be set before the robot.

It must be honestly admitted that this proposal is primarily directed at people interested in building machines, as the construction aspect dominates over programming Raspberry Pi. It will be used to collect data about the environment, transmit information from sensors and images. Let's ask ourselves whether we will observe our rover during its work – or control it completely remotely, as is the case with interplanetary missions. If the device is to operate somewhat independently, the list of tasks for which the onboard computer will be responsible is significantly expanded (tilt detection, collision detection, energy consumption monitoring, etc.). Fortunately, there are plenty of expansion modules for Raspberry Pi available on the market, which will facilitate the implementation of all the mentioned tasks.

Vision and television

On the Raspberry Pi board, there are connectors for connecting cameras and displays, which facilitates the construction of a range of interesting multimedia projects.

Photographic trap placed on a tree trunk in a camouflaging wooden enclosure.

Photographic trap

Often in articles about potential applications of Raspberry Pi, home automation and the inevitably associated monitoring are mentioned. And while the British computer is indeed excellent for realizing such a project, it's a bit of a shame to confine it within four walls. Low energy consumption means that the RPi module can be successfully battery-powered, and thus placed anywhere. This allows for the realization of a device called a "photographic trap," i.e., a camera placed in an inaccessible location (e.g., in the forest or inside a bird feeder/house), which will take photos or videos only when it detects movement. This gives us the chance to see the unknown life of familiar spaces: the yard, the nearby grove, the reserve, etc.

Powering Raspberry Pi with batteries is relatively easy to implement, as the computer has integrated voltage stabilizers and can be powered directly from the GPIO port – the system supplying 5V to this connector does not have to be exceptionally precise.

Generally speaking, a "photographic trap" can be realized in two ways. If we prefer an energy-efficient device (e.g., additionally equipped with solar cells), it would be better to use an external detector circuit (a simple motion sensor). In this case, a script running on the computer will monitor the state of a specific pin and activate recording only when it receives a signal of detected movement. Alternatively, the handling can be realized programmatically. Then the camera is active continuously, and the script analyzes the recorded image and saves only those fragments of recordings where an anomaly occurred, i.e., when an animal appeared in the frame. However, it should be noted that such a system will consume more energy, which will not allow for its long operation without replacing/recharging the batteries. It should be noted that our device will most likely also operate at night, so we will use a camera recording light in the infrared range, as well as additional LED IR lighting, which will contribute to increased power consumption. Of course, if we place our computer near the house, we can simply power it with a long cable or via LAN and PoE module (Power over Ethernet).

A significant advantage of using Raspberry Pi in such a project is the possibility of remote access to our device. Most commercial products of this type require physical access to the SD card on which images are saved. However, in the case of our own project, we can run a file server on the computer, which will allow us to remotely observe the results of the camera's work, e.g., via WiFi.

PVR

Since we have already expanded the functionality of one of the popular applications of Raspberry Pi, let's turn to another. In the context of this computer, multifunctional multimedia centers based on Kodi software are very often mentioned. It allows turning a regular monitor into a "smart" TV capable of playing materials from YouTube, all multimedia files, etc. Moreover, using a DVB-T2 module (i.e., a tuner), we can also receive digital terrestrial television via Raspberry Pi. How to expand the functionality of such a project?

Our receiving system can receive signals from many different types of sources, not only terrestrial television but also satellite and radio.

The biggest drawback of traditional television or radio is their schedule, to which the viewer and listener are forced to adapt. Many interesting programs/broadcasts, which may never make it to the Internet in OD (On Demand) form, simply escape us. We can avoid this by implementing an automated recorder that will record every interesting transmission according to the user's individual tastes. Such a device is not much different from a typical multimedia center, but it can receive signals from many sources, and also – if we program it that way – start recording not only according to the clock but also based on searching for keywords in their titles and descriptions of broadcasts. Our device will aggregate this information from selected sources (both the schedule transmitted within DVB signals and the Internet). A Python script with such functionality fits within the standard capabilities of this environment – it is also an interesting and satisfying exercise teaching HTML code parsing and data quantification.

Let's emphasize: limiting ourselves to DVB-T2 reception, i.e., terrestrial television, would be a loss for the capabilities of our device. With a little effort and relatively low costs, we can implement a recorder with much broader capabilities: capable of receiving radio signals (analog and digital), as well as satellite.

Radio amateur

Since we have already entered the topic of radio transmissions, let's look at the possibilities offered by SDR technology, or Software-Defined Radio. This is a general term for systems in which tuning the receiver/transmitter of electromagnetic waves is done using digital components. SDR modules connected to a computer via USB port are available on the market (to be purchased separately, as they are not included in RPi kits). They can be purchased in versions with basic functionality (limited to the role of a receiver operating on a limited band), as well as in the form of advanced devices capable of transmitting on many frequencies open to amateurs. It is worth noting that in both cases, the price will be very attractive, especially when compared to the offer of transceivers produced for radio amateurs. A small communication device combined with Raspberry Pi and appropriate software (more on that in a moment) is an excellent introduction to amateur radio hobby – cheap, easy to use, but also with very wide possibilities.

The free SDRangel software was created by enthusiasts. It contains a wide range of useful functions, conveniences, and tools for analyzing radio signals.

Receiving and analyzing radio signals can serve many purposes: from listening to transmissions made by radio amateurs (a special license is required to transmit!), to experiments with recording and emulating signals sent by remote controls, wireless devices, etc. The most popular software for handling SDR on Raspberry Pi is called SDRangel and is available for free. The screenshot above illustrates some of the possibilities of this application.

The breadth of SDR's possibilities is best evidenced by the fact that it allows reaching space in at least three ways:

1. Receiving conversations from an amateur satellite. In 2018, the Qatari satellite Es'hail 2 was launched into orbit. In addition to television transmitters sending a beam towards African countries, it includes a transponder (relay) for amateur radio communication, available to users in South America, Europe, North Africa, and Western Asia. Information about this project can be found by searching for the term QO-100, which is an abbreviation for Qatar-OSCAR 100 ("OSCAR" is a traditional name meaning Orbiting Satellite Carrying Amateur Radio). Using a satellite dish and a properly prepared antenna, we can use the SDR module to listen to signals transmitted by amateurs from four continents.
2. A similar installation will allow us to receive transmissions from weather satellites. Their signals are somewhat weaker but unencrypted. Most of them contain current images of large geographical areas – such photographs are taken to monitor the weather on a macro scale.
3. The third option, which would be a shame to omit here, is the periodic opportunities to communicate with astronauts on the International Space Station (ARISS project, Amateur Radio on the International Space Station). Scientists working there regularly conduct conversations (mainly with educational institutions), as well as send images to Earth using SSTV technology (Slow Scan Television). To receive these transmissions, a directional antenna is used, which must be aimed at the current position of the station – but Raspberry Pi, with the help of servomechanisms and data downloaded from the Internet, will allow this task to be automated.

Console

Creating a console for retro games is a very satisfying project, but also not a challenge. It only requires installing the appropriate software on Raspberry Pi, and that's basically it. But in the name of learning and ambition, we can complicate our lives – and at the same time construct a device that not everyone can boast of.

Emulating games allows access not only to old and nostalgically remembered titles – but also to positions that never reached our region, such as games intended exclusively for the original Japanese Nintendo.

Here, of course, there are many possibilities, but the two most interesting are a mobile device or the so-called retrofitting. The first project involves building your own console. This will require us to connect a display and make our own controller (GPIO inputs can be used for this purpose, or a circuit emulating a USB keyboard can be made using a microcontroller). The biggest challenge will probably be designing and constructing our own casing. The huge advantage of a console made this way is the ability to tailor it to our own needs (size, battery capacity). The second option for builders is breathing new life into a broken console or the casing of an old computer. Nothing stands in the way of placing Raspberry Pi in the body of an Amiga or Playstation. An additional challenge will be to make the project so that the factory-installed ports, keyboard, signal diodes etc., in the old equipment are used.

Everyday automation

When devising projects using miniature computers, it must be remembered that they exist primarily to serve our convenience. Raspberry Pi has the potential to streamline many everyday activities or create a device performing unusual, perhaps even strange functions, that no electronics manufacturer has thought of...

Car improvements

The OBD2 interface connector is often hidden behind a removable upholstery panel.

Individual tinkering with a car usually involves repairs, interventions in the sound system, making minor interior modifications. But the advancing standardization of automotive electronics today allows for the realization of several other interesting projects. Access to the CAN bus (Controller Area Network), which all electronic components in the car use for communication (including sensors and engine controllers), is possible through the OBD2 interface. Its socket is usually found near the driver's seat, often behind a removable panel. Using the appropriate adapter (this is not a large investment) and free libraries available for various environments (including Python), we can monitor the vehicle's condition in real-time. Usually, all the data available to the onboard computer will be available to us, i.e., engine speed, current gear, fluid temperature and pressure, fuel amount, etc. It is possible to create a program that will analyze the ride, its economy, etc. Using a computer and LED display or OLED, we can also create a so-called HUD (Heads Up Display), i.e., a display visible in the reflection of the windshield, allowing the driver to monitor selected parameters, e.g., speed, without taking their eyes off the road.

Another interesting project is observing the road through the vehicle's windshield, using a camera placed on the dashboard or behind the internal mirror. Using video processing libraries (e.g., OpenCV), we can not only record the route but also analyze the image. For example, note vehicle registrations and save or display their country/region of origin. A similar device would work on the same principle, collecting data on passed signs and providing the currently applicable speed limit.

Garden monitor

Monitoring conditions in the garden, or even in home pots, is a typical but scalable project that every electronics enthusiast should consider. Of course, provided that it does not stop at the trivial task of monitoring soil moisture.

The communication capabilities of Raspberry Pi allow for the creation of a complex network of sensors and actuators, which together will facilitate taking care of plant needs. Raspberry Pi will use them to check sunlight and temperature, perform periodic watering, fertilization, and even record growth. This project has many educational advantages due to the variety of necessary technologies. It will require some knowledge of communication methods, making a pump and valve controller, collecting data from sensors (here, one can attempt to record them in the cloud or a local SQL server running on Raspberry Pi). Some work will also be required to manually prepare an interface for such a device. It can be based, for example, on an HTML page. Taking the opportunity, it is worth expanding our project with the functionality of a weather station, which will obtain forecasts from public sources (many universities and institutions provide such data for free), examine atmospheric conditions, provide the perceived temperature, calculating it based on values obtained from a thermometer and an anemometer.

Monitoring conditions and automating irrigation in a greenhouse can serve both amateurs and professional gardeners.

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