Monthly Archives: August 2016

Quantum Dot Solids to Bring In a New Age Electronics

Quantum dot solids, a term for crystals fabricated from crystals may be the next thing after silicon wafers to bring about major changes in the field of electronics. Just as wafers constructed from single silicon crystals changed the tools of communication technology about half a century ago, a team of scientists in Cornell University working on quantum dot solids expects to transform this field further.

Larger structures from nanocrystals

The scientists grew larger crystals from nanocrystals of lead selenium. They then shaped square 2D superlattice structures by the process of fusion, taking care to maintain the atomic coherence. The atomic coherent lattice ensures that the atoms are directly connected to each other. There is no other intervening substance. As a result, these superstructures have superior electrical properties compared to those of existing nanocrystals of semiconductors. The researchers anticipate that this would aid absorption of energy and emission of light.

Tobias Hanrath, associate professor in Robert Frederick Smith School of Engineering, along with graduate student Kevin Whitham has led the study. The research findings have been published in Nature Materials.

Hanrath stresses upon the fact that the building blocks making up the superstructure have been designed with a degree of accuracy that matches with atomic scale precision. He goes on to say it would be reasonable to assume that the structures are as perfect as possible.

The current work is based on an earlier research done by the group, details of which have been brought out in a paper in Nano Letters in 2013. The study had dealt with new technique for bonding quantum dots. This involved monitored displacement or shift of ligands, which are connector molecules.

Tweaking the structure

Electronic coupling of each quantum dot or connecting the dots, as the paper has termed the process was considered a significant challenge. The new research appears to have resolved this problem. Compared to the previous structure consisting of nanocrystal solids linked with ligands, the new superstructure is vastly superior as it allows an ample scope for modifications. The nanocrystals undergo extremely strong coupling, which brings about energy band formation. Scientists can manipulate the bands according to the structure of the crystals. The researchers say that this maneuvering could lead to the development of new artificial materials with adaptable electronic structure and properties.

From lab to industry

Whitham does concede that a lot of work has to be done before starting production of these crystals on an industrial scale. The superlattice conceived by the group has several sources of flaws. This is principally because the nanocrystals making up the lattice are not exactly identical. The defects reduce the possibilities to which the electronic structure can be controlled. He points out furthermore, that the understanding of the structures formed by connecting the quantum dots is not yet complete and that this knowledge is essential for improving the results.

Whitham says that he expects that other scientists will further the work done by his team and improve upon the superlattice structure by removing the existing flaws. He is confident that additional research on the subject could lead to game changing techniques in the field of communication technology.

What is an Integrated Development Environment?

Those who develop and streamline software use IDEs or Integrated Development Environments. IDEs are software applications providing a programming environment for developing and debugging software. The older way of developing software was to use unrelated individual tasks such as coding, editing, compiling and linking to produce a binary or an executable file. An IDE combines these separate tasks to provide one seamless development environment for the developer.

Developers have a multitude of choices when selecting an IDE. They can choose IDEs made available from software companies, vendors and Open Source communities. There are free versions and those whose pricing depends on the number of licenses necessary. In general, IDEs do not follow any standard and developers select an IDE based on its own capabilities, strengths and weaknesses.

Typically, all IDEs provide an easy and useful interface, with automatic development steps. Developers using IDEs run and debug their programs all from one screen. Most IDEs offer links from a development operating system to a target application platform such as a microprocessor, smartphone or a desktop environment.

Developing executable software for any environment entails creating source files, compiling them to produce the machine code and linking these with each other along with any library files and resources to produce the executable file.

Programmers write code statements for specific tasks they expect their program to handle. This forms the source file and developers write in statements specific to a high-level language such as C, Java, Python, etc. The language of the source file is evident from the extension that developers use for the file. For example, a file written using c language usually has a name similar to “myfile.c.”

Compilers within the IDE translate source files to the appropriate machine level code or object files suitable for the target environment. The IDE will offer a choice of compilers suitable for the proper environment. In the next level, a linker collects all the object files that a program requires and links them together. Linking also takes in specified library files while assigning memory and register values to variables in the object files. Library files are necessary for supporting the tasks needed by the operating system. The output of the linker is an executable file, in low-level code, understood by the hardware in the system.

Without an IDE, the task of the developer is highly complicated. He or she must compile each source file separately. If the program has more than one source file, they must have separate names so that the compiler can identify them. While invoking the compiler, the developer must specify the proper directory containing the source files along with specifying another directory for holding the output files.

Any error in the source files leads to a failure in compiling and the compiler usually outputs error messages. Compilation succeeds only when the developer has addressed all errors by editing individual source files. For linking, the developer has to specify each object file necessary. Errors may crop up at the linking stage also since some errors are detectable only after linking the entire program.

Anoto – The Digital Pen & Paper Concept

John J. Loud holds the first 1888 patent for a ballpoint pen. He described this as a writing instrument capable of writing on rough surfaces such as wood, coarse wrapping paper and other surfaces that common fountain or quill pens could not. Unfortunately, Loud’s ballpoint pen was unsuitable for smooth writing and his patent lapsed. In 1938, Biro, a Hungarian newspaper editor, invented the actual ballpoint pen we are so familiar with today.

Writing on ordinary paper does not allow interfacing to the computer and transferring handwritten notes to the electronic media has always posed difficulties. However, a new development by Anoto Sweden is set to overcome this handicap faced by the humble ballpoint pen and paper and turn them into a suitable digital writing interface anyone can use.

The Anoto pen is hardly distinguishable from an ordinary ballpoint pen. Removing and replacing the cap constitutes a simple on-off function. In the Anoto concept, the pen has a digital camera and an advanced image processor inside it. Data from the pen travels wirelessly to the PC via a radio transceiver built into the pen.

The digital pen can use any ordinary paper printed with a special proprietary grid pattern. This grid only makes the paper look somewhat off-white to the user. The pen contains real ink that leaves its mark on the paper. A camera, built into the digital pen, takes snapshots of the grid nearly fifty times each second in infrared light and memorizes the position of the pen with respect to the grid. As the ink is invisible to the infrared camera, the pen keeps no record of the marks on the paper. The built-in memory stores several pages of handwritten text.

The Anoto patterned paper the user is writing on is actually a tiny part of one large sheet with several domains. These are set aside for various specific activities such as a digital notepad or licensed to companies for use as certain applications. Anoto can configure each domain for a different functionality, which the pen recognizes based on its position on the gird and reacts accordingly. The entire grid pattern covers nearly 60 million square kilometers so you can stop worrying over running out of paper.

The Sony Ericsson Chatpen from Sony is the world’s first digital pen built with the Anoto concept. It looks like a somewhat chubbier version of a normal ballpoint pen, offering little hint of the cutting-edge technology concealed within. There are other Anoto partners such as Vodafone, to supply the GPRS network and Esselte and 3M, to supply the paper products. Anoto is sparing no efforts for making this the standard infrastructure for digital paper. For this, Anoto is entering into alliances with Microsoft, MeadWestvacod and Logitech. Microsoft is incorporating the functionality of the digital pen into its .NET platform.

The Anoto digital pen and paper concept has an incredible scope of potential applications. As a simple example, you can scribble a quick note on your pad and then send it as a fax or an email simply by ticking the send box printed in a corner of your page. Astonishingly, you will be doing this without access to a computer.

EEG Controlling Music through Raspberry Pi

Imagine controlling Pandora with your brainwaves. Whenever a song comes up that you do not enjoy, make it switch to the next one. All you need is an EEG sensor, a pianobar and a single board computer such as the RBPi or Raspberry Pi. Once you train the RBPi to differentiate the bad from good music, you are good to go.

You need to train the Bayesian classifier to recognize good music from the bad. However, basic machine learning techniques do not always turn out very good. Therefore, with this time-series data, you can use it in sequences to reduce false positives.

Using an EEG headset to control songs you dislike is great, especially when you are moving around or doing something away from your computer. You simply slip on the Mindwave Mobile headset from the Brainwave Starter Kit and use the included app to see your brainwaves change in real-time on your mobile. You can monitor your levels of relaxation and attention while watching the response of your brain when you are listening to your favorite music. The Brainwave store has multiple brain training games and educational apps, which are classified according to age and personal interests.

Data from the Mindwave Mobile headset travels via Bluetooth to communicate wirelessly with the RBPi. Using the free developer tools available online from NeuroSky, you can write your own programs to interact with the Mindwave Mobile headset. On the Mindwave Mobile, you can see the EEG power spectrums of alpha, beta and other waves from your brain. With the NeuroSky eSense, you can even sense eye blinks and differentiate between attention and meditation states.

When using the EEG headset with the RBPi and a Bluetooth module, you can record data of some labeled songs that you like and some that do not appeal to you. From the Mindwave headset, the RBPi will get data on waves from your brain such as the delta, theta, low alpha, high alpha, low beta, high beta, mid gamma and high gamma. It will also get an approximation of your meditation and attention levels using FFT or Fast Fourier Transform. Additionally, the headset also provides a skin contact signal level.

It is difficult to make out much from the brainwaves unless you have received adequate training to do so. Machine learning helps here, as you can use software to differentiate good music from the bad. The basic principle is to use Bayesian Estimation to construct two multivariate Gaussian models, one based on good music and the other representing bad ones.

Initially, the algorithm may only be accurate about 70-percent of the time. Although this is rather unreliable, you can use the temporal data and wait for say, four simultaneous estimates before you decide to skip the song. The result is a way to control the songs played, using only your brainwaves.

Pianobar on the RBPi controls the music stream to Pandora. You start pianobar and then start the EEG program using python. It will tell you if the headset is placed properly on your head since it gives a low signal warning. Once it detects a song, it will skip it once it detects four bad signals in a row.

Monitor Your Solar System with a Raspberry Pi

Most photovoltaic systems contain parts such as the solar modules (panels) to provide the electrical power, a battery charger for converting the panel output to the battery voltage, a battery pack to store energy during the day and provide it during the night time, an inverter to transform the battery voltage to the proper line voltage for operating home appliances and an line source selector to switch between the solar and grid power.

When the sun is shining during the daytime, the solar photovoltaic cells convert the sunlight falling on them into electricity. Although the efficiency of the conversion may be only about 17%, solar power can easily reach 1KW/m2 and suitable panels can produce 5000 Watts in these conditions.

Solar panels typically produce a high voltage, 120V DC being a common figure. The battery charger has to convert this to match the battery voltage, generally 48V DC. Solar light power charges the batteries continuously during the daytime; therefore, the charger has to keep tracking the maximum power point to optimize the yield of the system. As the charger has to charge the battery also, this device forms the most elaborate part of the system.

With the above arrangement, the solar panels charge the battery during the daytime and the battery discharges during the night. The size of the battery depends on one day of consumption plus some extra to tide over an overcast day. That also decides the size of the solar panel. Batteries are essentially heavy and the lead-acid types generally have a lifespan of about 7 years.

The batteries feed the inverter, which converts the 48V DC into the line voltage – usually 230V AC or 110V AC. With a 5KW continuous rating, inverters can essentially run almost all household appliances such as the clothes dryer, the washing machine, the dishwasher and the electric kitchen oven. When the inverter is supplying a large load, the battery current may climb up to 200A.

Multiple sensors measure the solar field power from and temperature of the solar modules divided into arrays. The information comes to a PV panel via a CAN bus, which unites all the sensors. The PV panel also acts like a gateway between the CAN bus and a single board computer.

The tiny, versatile single board computer, the Raspberry Pi or RBPi is suitable for gathering data from the PV panel and storing them in a database. On the RBPi is a web server connected to the home Ethernet network.

Another set of sensors monitor the battery voltage, current and temperature. These are also on CAN bus and the information collects on a PV battery monitor board. A Wi-Fi module on the board acts as a gateway between the CAN bus and the Ethernet.

The boards and modules of the monitoring subsystem do not provide any interface with the user, except for a few activity modules. The system is meant for being supervised and controlled remotely. This is possible with a Web User Interface or an Android application.

Quadcopters Now Fly Below Water

It may sound bizarre, but it was bound to happen. Quadcopters, after they conquered flying in air, are now also equally capable of flying below water. Of course, submarine vehicles need a different build to keep the water from entering the system. Therefore, submarine quadcopters will always be sturdier and more expensive than their airborne counterparts will. You can witness the Deepflight Dragon – a beautiful quadcopter – on Lake Tahoe, California.

Graham Hawkes, submarine designer, was initially interested in aviation, but was disappointed as he was born too late for building airplanes in his backyard. Therefore, he concentrated his design expertise towards building Deepflight Dragon. Presently, the design is still in preliminary testing stage and the stabilization software is yet unfinished. Kip Laws, chief scientist of Deepflight, is delighted with the progress after the first test of the vehicle.

With its four vertical thrusters, Deepflight Dragon looks more like a two-seater Formula One car without wheels. You could easily pass it off as a flying car when on a helipad. Graham has applied aircraft technology to build the drone of the deep. It is a simple, stable vehicle able to move around freely and hovering when the driver wants it to – for whom it is a piece of cake to drive.

Graham first stumbled on the idea for the Dragon when he found people trying to build a full-sized quadcopter capable of carrying a man and flying like a drone. His calculations told him there would never be enough energy and endurance in a drone to carry the weight of a man and batteries while flying. However, if taken underwater, the buoyant force of water will help carry the weight – water is a fluid 850 times denser than air.

That made Deepflight Dragon a two-person underwater drone. One of the biggest advantages of flying underwater is the buoyancy provided by water. Deepflight Dragon has positive buoyancy, which means it naturally floats. Therefore, to submerge, it only has to pull itself downwards to the equivalent of five percent of its weight. This also allows Deepflight Dragon to have an all-day endurance with only a 15 KWHr battery pack.

The back cockpit of the drone has only two controls. The first is a lever on the left and the other is a joystick on the right. The lever is for engaging upward or downward vertical thrust, with the joystick making the sub move forward or backward, while also allowing it to turn left or right.

Although the controls look simple, they are somewhat different from those on an airborne copter, which simply tilts forward to go forward. As the Dragon has to pull downwards to get itself underwater, tilting the joystick forward actually makes it move backwards. Additionally, when the drone is moving forward, its rear end will go up, hindering vision.

All this makes it necessary to have a stabilization system to keep the sub on a level plane – with an extra set of thrusters mounted under the rear wing. Being in an X/Y orientation, these extra thrusters move the sub and allow it to make turns. That leaves the main four thrusters to control the depth of the sub and to level it.

Guiding Basics in Efficient Lighting Design

Discovery of fire and subsequently lighting has contributed hugely to the modern advancements in human life all over the world. However, only a few are aware of proper applications of lighting or that effective lighting also needs planning and design. Most people incorrectly infer lighting design to mean simply selecting lighting equipment for a system. Of course, selecting the most energy-efficient and cost-effective products is important, but they are simply the tools to achieve the design.

In reality, lighting design requires assessing and meeting the needs of the people who will use the space. It also requires skillful balancing between the functional aspects and the aesthetic impact of the lighting system.

That makes lighting both an art and a science. It also implies there cannot be any hard and fast rules for designing lighting systems. Additionally, there will also not be any single ideal solution optimum for all lighting problems. Typically, lighting designers face conflicting requirements and must set priorities before reaching a satisfactory compromise. Assets necessary for successful lighting designers include a proper understanding of basic lighting concepts, extensive experience, careful planning, assessment and analysis.

Lighting mostly involves use of energy. One of the chief concerns is achieving optimum energy efficiency, which means getting maximum lighting quality with minimum consumption of energy. This requires a combination of thoughtful design together with selecting the appropriate lamp, luminaire and control system. Additionally, decisions made must include informed choices of the level of illumination required, the integration and awareness of the space or environment being lit.

Lighting designers must have an intimate knowledge of the human eye and the way it perceives light and color. For example, light falling on an object is partly absorbed and partly reflected by the object. We see the object because of the reflected light entering our eye. The color of the reflected light also determines the perceived color of the object.

A flexible lens within the eye helps to focus the image on the retina and allows clear vision. The retina of the eye has many rods and cones. These convert light into electrical impulses that reach the brain via the optic nerve. The brain interprets the impulses into a proper image. However, illumination levels also change the way the eye perceives an object.

During the day and in normal daylight conditions, the cones in the retina enable us to see details in color. This is photopic or daytime adaption of the eye. As light levels dip, cones become less effective and the more sensitive rods take over. For example, in a well-lit street, the eye sees a mixture of cones and rods to see.

However, rods do not differentiate colors and respond only to different shades of black and white. The overall impression in average lighting is an image with lower color – the mesopic adaption. As light levels fall even further, such as in dim moonlight, the cones cease to function altogether and the eye loses all capability to see in color. This gives completely black and white vision – the scotopic or nighttime adaption.

Latest Touch Display for the Raspberry Pi

Those who were on the lookout for a proper touch display for their single board computer, the Raspberry Pi or RBPi can now rest easy. The official RBPi touch display is on sale at several stores and others will be receiving stock very soon. Users of RBPi models such as Rev 2.1, B+, A+ and Pi 2 can now use the simple embeddable display, instead of having to hook it up to a TV or a monitor. Watch the You-Tube video demonstration for a better understanding.

The new official touch display for the RBPi is a 7” touchscreen LCD. A conversion board interlinks the display module with the LCD and plugs into the RBPi through the display connector. Although the ribbon cable is the same as that used by the camera, the two do not work interchangeably. Therefore, identify the display connector first, before plugging in the ribbon cable from the display.

You can power up the display in one of three ways: using a separate power supply, using a USB link or by using GPIO jumpers. When using a separate power supply, you need a separate USB power supply with a micro-USB connector cable. The power supply must have a rating of at least 500mA and requires plugging in to the display board at PWR IN.

It is also possible to power the RBPi through the display board. For this, use an official RBPi power supply of rating 2A and plug it into the display board at PWR IN. Use another standard micro-USB connector cable from the PWR OUT connector and plug it into the RBPi power in point.

Powering the display from the RBPi GPIO requires using two jumpers – one from the 5V and the other from the GND pins of the GPIO.

After plugging in the ribbon cable and making one of the above power connections between the RBPi and the display, using the display requires updating and upgrading the OS on the RBPi. On rebooting, the OS automatically identifies the new display and starts to use it as its default display rather than the HDMI. To allow the HDMI display to stay on as default, the config.txt file must contain the line:

display_default_lcd=0

For further setup steps, follow these instructions.

The RBPi display comes with an integrated 10-point touchscreen. The driver for the touchscreen is capable of outputting both full multi-touch events and standard mouse events. Therefore, it is capable of working with ‘X’ – the display system of Linux, although X was never designed to work with a touchscreen.

For finger touch operations in cross-platform applications, the Python GUI development system Kivy is a great help. Although designed to work with touchscreen devices on tablets and phones, Kivy works fine with RBPi.

The 7” touchscreen display for the RBPi is of industrial quality from Inelco Hunter and boasts of an RGB display with a resolution of 800×480 at 60fps. It displays images with 24-bit color and a 70-degree viewing angle. The metal backed display has mounting holes for the RBPi and comes with an FT5406 10-point capacitive touchscreen.

The GoPiGo Robot Kit for the Raspberry Pi

Making a robot work with the tiny computer Raspberry Pi or RBPi has never been so easy. If you use the RBPi robot kit GoPiGo, all you will need is a small screwdriver with a Phillips head. The GoPiGo kit comes in a box that contains a battery box for eight or 6 AA batteries, two bags of hardware, two bags of acrylic parts, two motors, the GoPiGo board and a pair of wheels. For assembling all this into a working robot, follow these step-by-step instructions.

You start with the biggest acrylic part in the kit, the body plate or the chassis of the GoPiGo. Lay the plate on the GoPiGo circuit board and align the two holes with those on the circuit board. Place two short hex spacers in the holes below the body plate to make sure of which way is the upper side.

Next, you must attach the motors to the chassis. Use the four acrylic Ts in the kit for attaching two motors. Do not over tighten the bolts while attaching the motors, as this may crack the acrylic.

With the motors in place, it is time to attach the two encoders, one for each motor. These encoders fit on the inside of the motors and poke through the acrylic chassis of the GoPiGo. Encoders are an important part, providing feedback on speed and direction of rotation of the motor. If the encoders will not stay on, use blue ticky tacky to make them stay.

Now it is time to attach the GoPiGo board to the chassis. Place the GoPiGo board on the spacers and line its holes with the holes in the board before holding them together with screws. Two hex supports on the back of the GoPiGo board allow you to attach the castor wheel.

That brings us to attaching the wheels to the GoPiGo. You must do this gently, backing the wheels so they do not touch or rub against the screws. The battery box comes next, to be placed as far back on the chassis as possible. This gives it extra space and prevents the box from hitting the SD card on the RBPi.

This completes the mechanical assembly of the GoPiGo robot and only the RBPi remains to be attached. Locate the black plastic female connector on the GoPiGo and slide the GPIO pins of the RBPi into this connector. The RBPi remains protected by a protected plate or a canopy that has to be attached by screwing it on to the chassis.

Make the electrical connections according to the instructions. Be careful while flashing the GoPiGo hardware and leave the motors unconnected during the flashing. After connecting the GoPiGo for the first time, if you find any motor running backwards, simply reverse its connector.

GoPiGo comes with an ATMega 328 micro-controller, operating on 7-12VDC. SN7544 ICs handle the motor control part, which has two optical encoders using 18 pulse counts per rotation and a wheel diameter of 65 mm. External interfaces include single ports of I2C, Serial, analog and digital/PWM. The idling current consumed is about 3-500 mA, and full load current is 800 mA – 2A with both the motors, the servo and the camera running with the RBPi model B+.

What are Flying Probe Test Systems?

When testing a component or an electronic gadget, it is usual to hold two probes to the test points. Probes are metal prods insulated except for the tips touching the test points on one end and connected by flying leads on the other to an instrument. The instrument could be a voltmeter, an ammeter, an ohmmeter or a combination called the multi-meter. Such an arrangement is good for testing individual components or a printed circuit board. However, in a manufacturing scenario, where boards are produced in hundreds or thousands, humans cannot match the speed and special testing machines are used.

Such testing machines use a set of flying probe test systems for testing, trimming or alignment of components on a printed circuit board or a gadget. Most of these machines are computerized test beds with high speed, unprecedented positioning accuracy and extensive test coverage. They remove the requirement for a bed-of-nails testing fixture and provide a wide variety of test facilities contributing to validation of low-volume production and of the R&D department.

The typical configuration of a flying probe test system consists of four standard moving probes installed diagonally to the board under test. Advanced machines may also have two optional Z-mechanisms for holding another pair of moving probes that can move up and down vertically.

The vertical Z-axis probes enable access to test points that the standard moving probes find difficult to reach. In addition, the Z-axis probes can make proper contact with locations at different heights. With such flexibility, flying probe test systems can directly contact through-holes and heads of connector pins. To prevent slippages and false contacts, the probe tip may be of the dagger or inverse cone head type, all resulting in increased test coverage.

The testing machines are highly accurate measurement systems that include several 4-quadrant sources and measurement systems. Almost invariably, these are embedded with AC programmable generators that can also be used as function generators. Therefore, the testers are capable of applying measuring signals that are best suited to specific electronic components.

The measurement system associated with the flying probes usually features high-resolution ADC/DACs, which help to make precise tests and measure the dynamic characteristics of the circuit.

To enable accurate and repeatable measurements, these testers possess an XY table or stage made of highly polished native granite. Modern flying probe test systems boast of superfast movement of probes with positioning accuracies better than conventional models by at least 25%.

The super-fast movement is the result of using state-of-the-art high power and fast-moving drive motor systems controlled by new control software speeding up the test by 30-50% over conventional models. With the addition of three bottom probe units, combination tests can be performed more efficiently, further cutting down test times.

Modern flying probe test systems come with vision test systems offering simple AOI functions. Detection of missing, wrongly oriented or positioned components is made simple with the use of megapixel color digital cameras, backed by ring illuminations with high-intensity white LEDs. This combination is helpful in reading not only barcodes and 2D codes, but in color identification tests, OCR functioning and modifying contact points as well while debugging testing programs.