In 1966, Seymour Papert and Wally Feurzig developed the Logo Programming Language. As a part of this, Turtle Graphics was a very simple way of teaching programming to children. It consisted of a robotic turtle starting at coordinates 0, 0 in the X-Y plane on a computer screen. With a command turtle.forward(20), the turtle would move forward by 20 pixels in the direction it was facing, drawing a line as it moved. To turn the turtle where it is standing, a command turtle.right(30) would make it rotate 30-degrees clockwise. By combining the two commands and a few others, drawing intricate pictures and shapes on the screen was possible.

Now, the Python standard distribution contains a module “turtle” that allows extending the re-implementation of Turtle Graphics. You can run this on your tiny credit card sized inexpensive single board computer, the Raspberry Pi or RBPi. The Python module tries to keep the same merits as available with Turtle Graphics and is nearly fully compatible with it. That means the learning programmer can use the same commands, classes and methods interactively, when using the module.

For example, if you want to find out where your turtle is at present, you can query it with turtle.postion(), and the turtle will respond with its current X & Y coordinates. Now you can command it to move forward or backward, turn right or left and even check its orientation. For a complete list of the turtle commands, look up module-turtle. Apart from moving in straight lines, you can command the turtle to move in a circle of a given radius.

The Python module turtle is a versatile program. Various commands make the turtle do different things. For example, you may want the turtle to move but without drawing any line. Another command can make the turtle leave a stamped mark at its current position. Yet another command can make the turtle invisible, and another can make it draw lines in the color you specify.

Since RBPi is for children who are starting to learn computer programming, the combination of Turtle Graphics and RBPi is a powerful way of teaching them the basics of robotics. The language used by the module turtle is very similar to every-day English, which makes it very easy for children to learn and use.

Children find it difficult to grasp the abstractions on which traditional Euclidean geometry is built. For example, how do you have a point without size or a line that has a length but no thickness? Young people find all this difficult to grasp. However, the turtle being a real concrete object can be seen and manipulated. Turtle geometry being body syntonic, is easily understood since the turtle moves about just as everybody does. That makes it easy to identify with and its actions are well understood by kids.
Seymour Papert has explained the rationale behind turtle geometry in his book Mindstorms.

Another very simple way of learning turtle graphics on the RBPi is through Kids Ruby. Overall, with Turtle Graphics you can teach absolute beginners the concept of storing algorithms and running them so that the computer will simply obey the given commands.

In almost all airports, hotels, libraries, schools and restaurants, there is a proliferation of free unencrypted wireless access points, which are easily accessible to all. Additionally, with the spread of mobile devices, getting on the internet is no longer confined to the office or the home. Usually, a high number of users share the same open access point. Although this arrangement is very convenient for the users, it is also favorable for the snooper with the skills and intent to invade into others’ privacy and collect internet traffic for nefarious purposes.

Security professionals cry themselves hoarse while preaching restraint when it comes to using free/public wireless access points. However, for users wanting to access their office via the Internet, other than waiting to get back home, very few alternatives are available that are practical, free to use or at least almost free. However, the situation can be easily rectified with an inexpensive Single Board Computer, the Raspberry Pi (RBPi) in conjunction with the freely distributed OpenVPN software.

Offices/homes (SOHO) usually have a private network, which remote devices such as tablets and mobiles access through a typical Remote-Access Virtual Private Network (VPN) configuration. The mobile (the client) must authenticate itself successfully and the VPN server then establishes an encrypted tunnel. Now all traffic between the server and the client via the Internet will be securely routed to the private network through this tunnel, simply as if the mobile (client) had connected directly into the network itself. As the traffic is encrypted, anyone listening in will not be able to decipher the content, and the communication remains safe.

Such an arrangement as described above is very easily implemented with OpenVPN, which is an open source VPN implementation that was developed by James Yonan. OpenVPN is a highly customizable solution and supports a huge range of capabilities and options, including the most relevant five:

• Authentication and encryption ensures privacy
• Protection against Denial of Service and zero-day vulnerabilities
• Protection and privacy through proxy
• SOHO network access
• Broad device supports

OpenVPN was created for ensuring privacy, authentication and encryption, which it does via implementation of SSL/TLS concepts. Two encryption modes are used: Pre-Shared Key and TLS. Pre-shared key concept uses static keys that must be generated and shared with all devices for authentication, to establish and encrypt the secure VPN channel. This arrangement is more like a single lock with multiple users, each holding a key. TLS is a more secure arrangement with private/public key pairs.

To defend against Denial of Service or DoS attacks and Zero-day vulnerabilities, OpenVPN implements a variant of the HMAC key protection. Use of proxy disallows sites such as Amazon, Google or Facebook to establish the VPN client location since they are solely based on the IP address. This provides additional protection for the mobile device, since the Internet traffic is routed through the SOHO network. SOHO networks usually deploy additional boundary security, such as IPS, and this protection is extended to the mobile device when it connects through the VPN.

The OpenVPN service provides secure access to the resources available on the SOHO network without opening extra ports through the firewall. The device support is broad and covers Windows, Mac OSX, Linux and Android. For implementation on RBPi, more information is available here.

If you thought that the tiny credit card sized single board computer, the inexpensive Raspberry Pi or RBPi was only good for home automation and no more, you may be surprised to learn that it can do a lot more – control an entire building, for instance. Of course, it will need assistance in the form of an add-on board, such as the UniPi.

Very often, people have used the RBPi for automatically controlling their sprinkler systems, the lighting in their house or even for guarding their homes while they are away on a holiday. Commercial systems have often used the RBPi as a prototype. A Czech startup with the same name, the UniPi, is now offering a baseboard and an add-on board for building automation that you can use with your RBPi.

The RBPi plugs into the UniPi baseboard via its 26-pin expansion connector. With this combination of the UniPi and RBPi, you can control the entire functions of a modest sized building. For example, it can read signals from different sensors such as humidity, temperature and/or status of alarms and switches to control gates, sprinklers, curtains, doors, lights and more.

To help with the sensors and control, UniPi is also offering a passive sensor hub that comes along with a free temperature sensor and an optional waterproof temperature sensor, should you need one. The UniPi baseboard has 14 opto-isolated digital inputs that can read sensor signals from 5 to 20V and show the status with LEDs. The board can read 0-10V signals on two analog inputs and output 0-10V on another analog output. On-board is a 12V power supply, along with eight changeover relays, which can switch 5A at 230VAC. That makes UniPi adequate for controlling power to sensor devices for an entire building.

For reading sensors, the UniPi is equipped with a single-channel 1-Wire interface. That makes it convenient to connect hundreds of humidity and temperature sensors. UniPi even allows the second I2C port of the RBPi and its UART to be extended with 5V level converters and provides ESD protection for them. Power loss does not affect the timing of the board as it has an RTC or real-time clock module for keeping time. UniPi is compatible with the RBPi model B Rev2 and it is possible to configure it for the Rev1 model as well. However, UniPi does not mention the possibility of compatibility with the latest model of the RBPi, the 40-pin model B+.

On their website, UniPi offers numerous tutorials based on C/Python libraries for people wanting to develop UniPi applications on the Linux-based RBPi. For example, there is the Webiopi, which is specifically useful for connectivity with the Python Internet of Things. Additionally, there is the Wiringpi library for GPIO interfacing and other libraries for Adafruit.

UniPi is offering its baseboard with on RJ45 connector for the 1-Wire interface and two RJ11 connectors – one for the UART and the other for the external I2C. It has one P1 header and another P5 header along with a 2.1mm standard power connector and an RBPi power jumper.

You may rightly question the logic behind using apples as switches for your Raspberry Pi, as against the usual hard plastic ones. Well, for one, we live in an analog world and there is much more fun in integrating items of daily use with your computer. For another, it pays to see the look of astonishment on someone’s face when picking an apple from a basket, if the computer were to reprimand him.

The tiny credit card sized single board computer, the ever-popular Raspberry Pi or RBPi can sense inputs with capacitive touch breakout boards. This is the basics of using several household objects as input sensors for the RBPi. You can use any conductive object, not only an apple, such as pencils (the graphite part), spoons and potatoes including any other fruits or vegetables that you may find handy.

Capacitive touch sensors detect the tiny amount of electric charge every human body carries. The breakout boards have a pad that is sensitive to touch. You can extend this pad to any object by attaching a wire, allowing the object to develop a sensitivity to touch. You will of course need to inform the RBPi of your intentions and to do that, put in some effort in programming it. Get help from this website.

With the hardware above and a few lines of Python, you will soon have a new way of controlling your projects and games that is fun and easy at the same time. There are three types of breakout boards that you can experiment with.

The first type is the momentary capacitive touch sensor. This detects as long as something continues to touch it. The sensor has an LED that glows when anyone touches the pad and remains lit until it detects the end of touch. This breakout board has a large touch-pad and a small copper hole near it. You can solder a piece of wire to the hole and extend it to a capacitive item such as a drawing you have made with pencil (graphite).

The second type of breakout board is the toggle type of capacitive touch sensor. The LED on the board comes on as soon as you touch its pad. The LED remains lit up even when you lift your finger off the pad. The LED will go off once you touch the pad again. Therefore, when you solder a piece of wire to the hole near the touch-pad and connect its other end to any conducting item such as a spoon, you can easily detect if someone has touched the spoon at least once.

The third breakout board is the most versatile of the lot. Surprisingly, it does not have any touch-pads, although it is named as a 5-pad capacitive touch sensor. Instead, it has five copper holes, so that you can connect five objects with five pieces of wire. Therefore, if you have five different fruits or vegetables, you can connect them up and the RBPi will help you to chart their individual responsive speeds against touch.

While the two boards will both need a 10K resistor each connected between the object and the board, the 5-pad touch sensor board does not require any resistors, as it has them on-board.