Category Archives: Guides

Electronics for Indoor Farming

With global population growth, there is increasing concern over the sustainability of ecologically friendly farming. Farmers are now adopting innovative technologies for improving the overall efficiency of farming. Among them, the Internet of Things or IoT shows a greater promise with real-time, wireless, and remote sensing, monitoring, and control of indoor farming conditions and operations, such as humidity, moisture levels, soil pH, temperature, and lighting.

Most of the functions mentioned involve complex combinations with farmers often struggling to combine LED lighting, wireless communications, actuators, and sensors with control and mobile applications for gathering the optimum information, analyzing it quickly to generate the appropriate response, and acting upon it. Even for the technologically proficient, implementing existing product offerings is a challenge for deploying a low-power, scalable, cost-effective, reliable, and secure system.

Arrow Electronics, in combination with eInfochips and Analog Devices, offers an end-to-end, one-stop solution for the above problems in the form of the Grow House Evaluation Kit. Their starter kit has the best of technologies, including power management, converter, and signal conditioning from Analog Devices. The kit comes with sensors for moisture and pH, wireless connectivity, LED lighting with a dimming facility, along with remote accessibility via a cloud-based dashboard. All these are available on the iOS and Android platforms.

The Grow House Evaluation Kit is a smarter way to set up indoor farming operations. With wireless connectivity from Silicon Labs, LEDs from OSRAM Light Engine with dimming and color control, the cloud-based dashboard provides remote accessibility for moisture and soil pH levels through ruggedized connectors from Amphenol.

The soil-monitoring node included with the Grow House Evaluation Kit uses leading-edge technologies from Analog Devices. Included in this soil-monitoring node are the power and analog solutions for measuring the pH and moisture levels of the soil with high accuracy for maximizing crop yield.

The IoT gateway included with the kit is based on a platform from Qualcomm 96Boards. The LED node in the kit features the ability to control the color output, intensity, and the UV spectrum of the custom light engine.

Pre-certified ZigBee modules from Silicon Labs implemented with the IoT gateway provides custom control of the LED and Soil nodes. Arrow Electronics offers mobile applications compatible with iOS and Android platforms for configuration and control of the LED and Soil nodes. Arrow Electronics also offers a light engine with OSRAM OSLON Square high-power LEDs, along with design files for customization, but the LEDs are only for demonstration.

Those looking for the complete Growhouse Platform need to order three nodes independently for configuration of the Growhouse. These are the LED Node, IoT Gateway, and the Soil Node.

Vertical farming operations benefit extensively from digital transformation solutions from Arrow Electronics, thanks to their advances in technologies involving sensors and connectivity, and easy access to cloud infrastructure providing cost-effective operations. Although timer-controlled pumps, lighting, and fans do help in farming, digital transformations such as those provided by the Growhouse Platforms go far beyond the simple methods. A digital grow house based on the Grow House Evaluation Kit enables this transformation in the easiest way possible.

Flexible Heaters and Multiple Heating Zones

Flexible heaters are suitable for a wide range of uses that require variable heating options. While providing optimal heat transfer, they also offer the right temperature for products like foodservice, medical devices, sensors, instrument panels, and electronics.

We are accustomed to thinking of heaters in standard shapes like square, round, and rectangular. However, customized flexible heaters are available in a wide variety of shapes that have the requisite shape to wrap around specific objects like inserts and pipes. They may also have different temperature zones for applications that generate their own heat in some places while requiring heating in others.

Designers make flexible heaters from polyimide and silicone rubber, and their size depends on the resistive element necessary. For very thin flexible heaters, etched foil heaters are the most suitable, and both polyimide and silicone materials can use them. Etched foil heaters are also suitable for smaller flexible heaters, as they can be as small as 1-inch square, or as large as 18 x 24 inches for silicone rubber, and 10 x 70 inches for polyimide. For larger sizes, designers prefer wire-wound resistive elements.

If necessary, designers can make flexible heaters in odd and non-symmetrical shapes as well. However, the specific needs of the application almost always define the shape, requiring laser cutters and mechanical equipment for creating the outline of the desired shape. Recent developments ensure that internal cutouts are also possible, such as in rectangular, square, circular, and other shapes, without sacrificing the reliability and heating capacity of the flexible heater.

Etched foil elements allow quick thermal transfers and faster warmups for heaters made from both polyimide and silicone rubber. However, wire wound heaters are notably slower, and there may be a delay in heat transfer when the heater element is wire-wound. Wire wound heaters are not suitable for polyimide heaters.

Some applications do not require heating equally throughout the surface. For instance, some electronic circuitry may create its own heat, protecting itself from external or internal temperature changes. Such applications do not require additional heating. However, outside this protected zone, the rest of the circuitry may require suitable temperature control for proper operation. Engineers provide suitable heating with cut-outs along the heater material. Flexible heaters with multiple heating zones are the answer for applications that require heating but at different temperatures.

Flexible heaters made from polyimide or silicone rubber are the most suitable for such applications. Multiple zone heating is necessary if some part of the electronics requires heating at a certain temperature, while another part needs raising to a different temperature.

Making heaters with multiple heating zones requires designers to place different heating elements at suitable places, with separate controls for these zones. However, other simpler options are also available, requiring one heater and a single controller. One of the options involves using elements with variable widths.

The width of the conductor of foil etched heaters impacts the watt density in specific areas of the flexible heater. When the width of the conductor is low, its resistance increases resulting in lowering the thermal output at that zone, creating multiple heating zones.

Motor Run & Motor Start Capacitors

Electric motors exploit the interaction between two magnetic fields for rotating a shaft. The stator windings generate one of the fields, and the rotor windings provide the other. In some DC motors, permanent magnets replace one of the windings, while the commutator, whether brushed or brush-less, changes the direction of the current in the other winding to continuously alter the interaction between the two magnetic fields to allow the motor to rotate.

In three-phase AC motors, the interaction between the three incoming phases creates the rotating magnetic field in the stator windings, and this pulls the rotor along, making it rotate. The so-called single-phase AC motor is, in reality, a two-phase AC motor that is operated with a single-phase supply, with capacitors generating the second phase. These motors require two capacitors, one to start the motor, and the other, to keep it running.

A capacitor is a device to store charge. In the DC circuit, a capacitor will charge up and stay that way until allowed a path to discharge. In the AC circuit, where voltage and current change polarity regularly, the capacitor charges up to the peak voltage in one cycle, then discharges and again charges up to the negative peak in the next cycle, with the rate of charging and discharging dependent on the capacitor value and the impedance in the circuit.

Another important factor is the voltage on the capacitor does not follow the input voltage while it is charging and discharging—it lags behind. Even though the supply voltage may be at its peak, the voltage on the capacitor reaches the peak only after the capacitor charges. Likewise, as the supply voltage moves towards the negative peak, the capacitor voltage follows more slowly as the capacitor has to first discharge. This lag helps to create the second phase for the motor.

A motor starting from rest requires a high starting torque, but once it has started moving, requires a smaller running torque to keep it in rotation. That means a larger capacitor is necessary for starting the motor—providing it with a larger starting current. In fact, motors use a centrifugal relay to cut out the start capacitor from the circuit after the motor has reached a certain speed. The run capacitor, though, has to remain connected to the motor at all times.

As the run capacitor is engaged in the circuit continuously, they are oil cooled and in metal, cases to allow heat dissipation. As they face peak to peak voltages all the time, their voltage rating tends to be on the higher side—typically, 1.5 times the line voltage, although the capacitance value may be low, ranging between 5 µF and 45 µF. On most 240 V systems, run capacitors are likely to be rated 370-440 VAC, and in 480 V systems, 600 VAC capacitors are more common. Run capacitors are rated for 100% duty cycle.

Start capacitors, being of larger capacity, are physically larger as well. As the start current does not need to be very precise, start capacitors are available as 8.3 µF, 15 µF, 43 µF, 60 µF, and above. Common voltage ratings for start capacitors are 110, 125, 165, 220, 250, or 330 VAC.

Storing Data with Light

Currently, we have several methods of storing and transmitting data. The most common method followed is storing data on a magnetic hard disk in the form of bits. Here minute magnetic domains form a North and a South pole pair, with the direction of the magnetization of the poles defining whether the stored bit is a digital 1 or a 0. Writing the data means physically switching the magnetization of the relevant bit, one at a time.

Switching or changing the magnetization of each bit requires the application of an external magnetic field, which forces the alignment of the poles to change to either up or down for representing a digital 1 or a 0 respectively.

However, it is also possible to use light to flip the magnetization. Two things are required here, one, very short laser pulses of femtosecond wavelength, and the second, synthetic ferrimagnets that respond to these laser bursts. Using laser and ferrimagnetic material makes data storage far faster compared to what can be achieved by magnetization alone. Ferrimagnets are materials that work with spintronics with the application of a femtosecond laser pulse, and that makes the whole process extremely fast and energy-efficient.

As such, light offers the most energy-efficient method of sending and receiving information. However, storing light is not an easy task. That is the reason data centers all over the world prefer to use magnetic storage methods such as tapes and disks, even though these methods consume a lot of energy to operate. This hybrid technique of storing information using lasers and electric current, developed by researchers at TU Eindhoven at the Institute of Photonic Integration, was presented in the journal Nature Communications. The new method combines the advantages of the high speed of light and ease of magnetic storage. They are using ultra-short pulses of light to write the information directly on a magnetic medium, the result is highly energy efficient and the speed of operation matches the speed of light.

Scientists using the above method of data storage with lasers, have another trick up their sleeve. They combined this optical switching with race-track memory. Here, the data is stored inside a magnetic wire and transported using an electric current. Now, as soon as the bit is stored at one end of the wire using the laser burst, it can be efficiently transported along by the current, freeing up space and thereby allowing the laser to write the next bit.

This efficient on-the-fly operation with the help of lasers and current using magnetic race-tracks does not require any intermediate electronic step. In fact, the physical analogy the scientists offer for this method is of a person jumping back and forth between two high-speed trains moving alongside each other, instead of using a station to change over from one train to the other. The laser and current method, therefore, represents faster speed and higher efficiency.

Obviously, the wires are actually micro-wires. The scientists who designed the system plan to reduce the wires to nano-scale in the future to enable them to be integrated inside chips. They are also working on reading information using optical methods.

Role of LEDs in Horticulture

While LEDs have revolutionized indoor and exterior lighting methods, they have been revolutionizing operations involving indoor grow facilities. This is mainly because LEDs are highly flexible in their spectral output, while their efficiency is very high. That means they emit much lower heat.

A new standard from ASABE specifies the performance of LED lighting products for horticulture applications. The standard spells out the test methods to measure the optical radiation from LEDs in the range 280-800 nm. Note the visible spectrum covers about 390-700 nm.

According to the Standards and Technical director of ASABE, Scott Cedarquist, in horticultural applications, LED lighting has generated very high levels of interest in their projects in the last 20 years. Therefore, horticultural lighting makes use of several terminologies that are primarily focused on plants. Two of them are PPFD or Photosynthetic Photon Flus Density and PPF or Photosynthetic Photon Flux.

While PPFD measures the number of active photons falling on a surface per unit area per unit of time, PPF is the number of photons created by a lighting system per second.

Horticultural lighting primarily focuses on delivering photons that initiate photosynthesis and other processes in plants. These spur plant development as they excite electrons. Horticultural applications use LED products that are different from those used for general illumination. The difference is primarily that the former has a wider spectral output typical for horticultural applications. This is necessary as different plants respond differently to various wavelengths.

According to academic and industry research, each type of plant has a specific light recipe that helps the plant to yield higher growth in the shortest period. The recipe holds the variation in optical spectra for optimizing the overall growth of the plant, thereby improving desirable plant characteristics. For instance, increasing the potency of cannabis or the flavor of vegetables.

The light output from LEDs has another characteristic. Not only do LEDs provide a precise output spectrum, but this spectrum can also be tuned to optimize the spectrum for different plants and the phases of their life.

LED lighting products are primarily used in horticulture as vertical farms. This is due to the far lower heat output from LEDs as compared to that from other light sources. This allows the LEDs to be interspersed very close to the plants without damaging them. Therefore, facility managers are able to maximize the use of available space. This has made vertical farming very popular in urban areas. Horticulturists are making use of abandoned buildings which they are converting to grow food, thereby making new products available at cheaper rates.

The high efficiency of LEDs also helps considerably in energy savings. However, grow facility managers are more interested in the yield of the crop, and use of LEDs for high-value crops such as cannabis offer revenue increase from higher yield and shorter life cycle, rather than from energy savings. Similarly, more traditional crops such as flowers and leafy vegetables also use LED lighting not for energy savings, but rather for the ability to produce more crops in a shorter period.

What are Laminated Bus Bars?

Rather than use one solid bar of copper, the industry prefers laminated bus bars. These are fabricated components with layers of engineered copper bars separated by flat dielectric materials, bound together into a unified construction. Laminated bus bars offer several advantages—improved reliability and reduced system costs. They are available in various sizes and shapes, some as big as a fingertip while others more than twenty feet in length. Several industries use multilayered bus bar solutions routinely and they include telecommunications, computers, industrial, military, transportation, alternative energy, power electronics, and many more.

Laminated bus bars are good for reducing the system costs, improving system reliability, increasing capacitance, lowering inductance, and eliminating wiring errors. Additionally, the physical structure of the bus bars also acts as structural members of a complete power distribution subsystem. Multilayer bus bars function as a structural integration that other wiring methods cannot match.

The decreased assembly time and the internal material handling costs for laminated bus bars bring down the overall manufacturing costs. Assembly operating procedures can be difficult to follow and assemblers often resort to guesswork, leading to wiring errors. Using laminated bus bars eliminates this totally, as installers have to terminate various conductors at specified locations. Not only does this reduce the parts count, it also reduces ordering, inventory costs, and material handling.

Fabricators can make laminated bus bars fit specific needs and customize them for maximizing efficiency. The use of laminated bus bars, therefore, helps the organization build quality into processes. With reductions in wiring errors, the organization has fewer reworks, and they can lower their quality and service costs.

Laminated bus bars offer increased capacitance and lower inductance, resulting in lower characteristic impedance. The benefit to the industry is greater noise cancellation and effective noise suppression. Manufacturers can control the capacitance by using dielectrics of various thicknesses and different relative K factor.

Multilayered bus bars can replace cable harnesses—this eliminates mistakes in wirings. Moreover, failure rate of bus bars is extremely low, while wiring harnesses fail very often. That makes repairing and or replacing wire harnesses an expensive process, while using bus bars in the system is adding an effective insurance.

According to physics, a conductor carrying current develops an electromagnetic field around the conductor. As laminated bus bars have thin parallel conductors with thin dielectric material separating them, the effect of inductance on electrical circuits is a minimum. With opposing potentials laminated together, the magnetic flux cancellation reaches a maximum. Semiconductor applications routinely use laminated bus bars to reduce the proximity effect. GaN and or SiC high frequency circuits also use laminated bus bars to reduce high electromagnetic interference.

Using wide and thin conductors and laminating them together to form bus bars actually decreases the space requirement, thereby allowing a better airflow in systems and improving system thermal characteristics. Moreover, the flexibility of these bus bars provides the industry with a wide variety of interconnecting methods. Assemblers commonly use tabs, embossments, and bushings for installing laminated bus bars. Manufacturers also offer pressed-in fittings that can integrate into the design. This makes laminated bus bars compatible with almost any type of interface.

Are Ferrites Good for Interference Suppression?

Although ferrite beads and sleeves are a common sight on cables, the technique for reducing both outgoing and incoming RF interference is the least understood. To study ferrites, and to do some comparative frequency domain measurements, one needs actual ferrite samples, a specially designed test jig, a spectrum analyzer, and a tracking generator.

Any current flowing through a metal conductor will create a magnetic field around it. The inductance of the conductor transfers the energy between the current and the magnetic field. A straight wire has a self-inductance of about 20 nH per inch. Any magnetically permeable material placed around the conductor helps to increase the flux density for a given field strength, thereby increasing the inductance.

Ferrite is a magnetically permeable material, and the composition of the different oxides making it up control its permeability, which is frequency dependent. The composition is mainly ferric oxide, along with nickel and zinc oxides. Furthermore, the permeability is complex with both real and imaginary parts. Therefore, the line passing through the ferrite has both inductive and resistive components added to the impedance.

The ratio of these components varies with frequency. The resistive part dominates at higher frequencies, and the ferrite behaves as a frequency dependent resistor. Therefore, the assembly shows loss at high frequencies, with the RF energy dissipating in the bulk of the material. At the same time, there are few or no resonances with stray capacitances.

Cables are usually in the form of a conductor pair, carrying signal and return, or power and return. Multi-way cables may carry several such pairs. The equal and opposite return current in each circuit pair usually cancels the magnetic field from the current in the forward line. Therefore, any ferrite sleeve place around a whole cable will have zero effect on the differential mode currents in the cable. This is true as long as the sum of differential-mode currents in the cable is zero.

However, for currents in the cable in common mode, with conductors carrying current in the same direction, the picture is different. Usually, such cables produce ground-referred noise at the point of connection or have an imbalance of the impedance to ground, causing a part of the signal current returning to ground through paths other than through the cable.

For instance, a screened cable, improperly terminated, may carry common-mode currents. As their return paths are essentially uncontrolled, these currents have a great potential for interference, despite being of low levels. Sometimes, the incoming RF currents, although generated in common mode, convert to differential mode and so affect circuit operation. This happens due to differing impedances at the cable interface.

As common mode currents in a cable generate a magnetic field around it, placing a ferrite sleeve around the cable increases the local impedance of the cable and operates between the source and load impedances.

When interfacing cables, low source impedance implies the ferrite sleeve is most effective when adjacent to a capacitive filter to ground. Since the length and layout of a cable will usually vary, engineers take the average value of the cable impedance as 150 ohms.

How do Antistatic Bags Work?

Computer boards and sensitive electronic components need protection from electrostatic discharge, especially at the time of shipping, handling, and assembly. This requirement has led to the development of an entirely new class of antistatic packaging materials. Now, a multi-million dollar packaging industry exists, with major developments in polymers. These are special conductive polyethylene and other laminates covered with very thin metalized films. This packaging industry saves several hundred million dollars each year for the computer and electronic industry, dwarfing almost all other industrial and commercial antistatic abatement enterprises.

To demonstrate the working of an antistatic bag that store and ship assembled boards and electronic components, one needs an apparatus including a tonal electrostatic voltmeter or TESV, several antistatic bags big enough to cover the TESV mounted on a tripod, a plastic tube or rod, and a rubbing cloth. Wool or silk cloth will work well with a Teflon, Nylon, or PVC pipe.

To disallow any movement of the TESV when operating, mount the instrument on a tripod, turn it on, and zero the instrument. Now charge a plastic rod by rubbing it with the cloth, and bring it close to the sensing head of the TESV. The instrument will respond by indicating the presence of electrostatic charge.

Covering the TESV with one of the antistatic bags shows it now registers little or no charge when repeating the experiment. Even with the charged conducting object discharging directly to the bag, the TESV shows little or no charge indication. The only possible explanation is the conductive bag shields the TESV from the electrostatic field.

The bag shields the instrument even though it is not connected to ground. If it were necessary to ground the bag to make it work, the antistatic bag would have been more inconvenient and ineffective than they are now. Grounding is not necessary here as electric charge resides only on the outer surface and does not penetrate inside, or into any void enclosed by the conductive material. The ungrounded bag simply holds the charge harmlessly only on the outside.

This also solves the problem of removing a sensitive component from inside the bag. When a person handles the bag, the contact with the hand grounds the bag and drains the charge from its surface. However, if the person were wearing an insulated glove, the component would draw a strong electric spark when it is withdrawn from the bag, and may be damaged.

Antistatic and static shielding materials are commercially available for every size and shape necessary. Specifications usually refer to MIL standards or the rate of charge dissipation, along with abrasion resistance, thickness, and others. Some advertisers refer to their antistatic bags as Faraday cages, since it does not allow charge to penetrate inside the bag.

Another type of antistatic bag has no metal layer, but is actually a bag made of a conductive polyethylene film. The manufacturer claims the bag can dissipate 5 KV in 2 seconds. Although in practice it is the electric charge that dissipates, the voltage is far easier and more convenient to monitor, and is directly proportional to the charge for a fixed capacitance geometry.

Problems Mains Harmonics Cause

Single-phase power converters are specifically problematic since they generate significant levels of triplen harmonics, such as the 3rd, 9th, 15th, etc. As they do not undergo phase cancellation, they add up linearly in the neutral conductor to create a particular nuisance. Apart from this, they are also present in zero-phase transformer flux, and heat up cables and transformers. Although three-phase converters also generate harmonic emissions, the triplen currents produced by them are of much lower levels.

Other non-linear loads also contribute to harmonic currents in the mains supply. Such loads include motors and transformers, welding equipment and arc furnace rectifiers. Another source is the fluorescent lamp with magnetic ballast. However, rectifiers produce much higher frequencies as compared to that from fluorescent lamps.

The harmonic currents an equipment draws from the AC mains supply do not alter the power the equipment consumes when measured in Watts. However, the harmonic currents increase the VA rating of the equipment. Since Power Factor is the ratio of the Watts to the VA the equipment consumes, the equipment that produces significant emissions of harmonics also has a lower power factor.

A resistive load, such as an incandescent lamp, has a PF of 1.0 since it consumes the same amount of power in Watts, as it does in VA. Therefore, an incandescent lamp cannot emit any harmonic content. On the other hand, electronic equipment with rectifiers at the input and with no harmonic reduction techniques have power factors of around 0.6, implying they generate harmonic currents. Fluorescent lamps with magnetic ballast, running at 50/60 Hz, usually have PF of the order of 0.3, so they generate significant amounts of triplen harmonics.

The power factor of the load is significantly different from the power factor traditional electrical generation and distribution engineers use—the latter is the cosine of the angle between the sine-wave supply voltage and its load current. While the traditional PF assumes all loads are linear using sine wave voltages, engineers adjust this PF by adding capacitance or inductance to the power line, depending on whether the load is resistive, inductive, or capacitive.

However, the traditional method of PF correction for linear loads fails when trying to correct the PF of a rectifier-input electronic power converter. Mains power distribution networks are now driving significant numbers of electronic loads as these operate at higher efficiencies, and electronic loads are now replacing most linear loads.

The standard IEC 61000-4-7 [6] offers a survey of harmonics present in power supply systems. Typically, there are four major kinds of problems that harmonic currents cause when they are flowing in mains power supply networks:

  • Problems that harmonic currents themselves cause
  • Voltage distortion from harmonic currents
  • Problems that voltage distortions cause
  • Interference to telecommunication networks

In large installations with several single-phase electronic loads, such as in modern offices, the total neutral currents may reach as high as 1.7 times the highest phase current. This is the effect of harmonic currents, mainly the triplens, as these flow without being cancelled, in the neutral conductor. As many older buildings have half-sized or even smaller diameter neutrals, there can be a risk of fire hazard.

Raspberry Pi and Traffic Lights

Although we come across traffic lights almost every time we step out of our homes, we rarely stop to think about how they work. However, Gunnar Pelpman has done just that, and he has put the hugely popular single board computer, Raspberry Pi to good use. While most of the tutorials introduce turning on and off LEDs, he has prepared a somewhat more complex tutorial, one that teaches how to program traffic lights. Moreover, he has done this with the Raspberry Pi (RBPi) running the Windows 10 IoT Core.

Traffic Lights may look very complicated installations, but they are rather simple in operation. They mostly comprise a controller, the signal head, and the detection mechanism. The controller acts as the brains behind the installation and controls the information required to light up the lights through their various sequences. Depending on location and time of the day, traffic signals run under a variety of modes, of which two are the fixed time mode and the vehicle actuation mode.

Under the fixed time mode, the traffic signal will repeatedly display the three colors in fixed cycles, regardless of the traffic conditions. Although adequate in areas with heavy traffic congestion, this mode is very wasteful for a side road with light traffic—if for some cycles there are no waiting vehicles, the time could be more efficiently allocated to a busier approach.

The second most common mode of operation of the traffic signal is the vehicle actuation. As its name suggests, the traffic signal adjusts the cycle time according to the demands of vehicles on all approaches.

Sensors, installed in the carriageway or above the signal heads, register the demands of the traffic. After processing these demands, the controller allocates the cycle time accordingly. However, the controller has a preset minimum and maximum cycle time, and it cannot violate them.

The hardware for the project could not be simpler. Gunnar has used three LEDs—red, orange, and green—to represent the three in a traffic light. The LEDs have an appropriate resistor in series for current limiting, and three ports of the RBPi drive them on and off. The rest of the project is the software, for which Gunnar uses the UWP application.

According to Gunnar, there are two options for writing UWP applications—the first a blank UWP application and the second a background application for IoT—depending on your requirement. The blank UWP is good for trying things out as a start, as, at a later point of time, you can build a User Interface for your application.

After creating the project with the blank UWP application, Gunnar added a reference to Windows IoT Extensions for the UWP. Next, he opened the file MainPage.xaml and added his own code, which begins with a test for the wiring. He uses the init() function to initialize the GPIO pins and stop() to turn all LEDs off. Then the code turns on all LEDs for 10 seconds to signal everything is working fine.

According to Gunnar, the primitive code mimics the traffic lights. He uses a separate code for the cycling of the traffic lights, and another for blinking them on and off. He uses the play() function for running ten cycles of the traffic light.