Battery Monitoring with Comparators

So many portable consumer electronics gadgets in use today use small, button- or coin-cell batteries. Sometimes it is necessary to monitor their state-of-charge (SOC) and health efficiently without affecting their SOC significantly, but this can be a challenge. However, simple low-power monitoring circuits for small batteries using comparators can overcome this challenge.

Managing Batteries in Portable Systems

Usually, the system engineer budgets the system power requirements carefully during the system design. A micro-controller or microprocessor within the gadget is the actual brains that manages the system reliably and performs the required functions. Since it is typical for the controller to be power-hungry, as it is the workhorse of the system, there is not much sense in making the controller do all the work. To prevent unnecessary power dissipation, the controller is designed to remain asleep for extended periods, only waking up when flags are presented on the GPI pins.

Therefore, engineers resort to using low-power circuits for continually monitoring the vital functions of the system. When these circuits detect an event, they flag the micro, usually in the form of interrupts. The micro then wakes up to perform its required duty. One of the vital functions of such circuits is to monitor the state of the battery. When the battery voltage dips below the pre-defined threshold, it means it has discharged and requires charging. Likewise, as soon as the battery voltage crosses another pre-defined threshold, it means it is completely charged with no further requirement of further charging. Similarly, it is important to monitor the case temperature of the battery and the ambient temperature, as this provides much information about the loading conditions on the battery, and the presence of a fault.

Using Comparators for Monitoring

Although there are sophisticated battery monitors with fuel gauges, and monitoring battery voltage and temperature with an analog-to-digital converter is possible, these essentially require careful tradeoffs with portable gadgets. A designer must consider form factor, cost, accuracy, speed, and power consumption when creating the design, as different systems may have different priorities.

It is possible to have a simple comparator monitoring the voltage at the battery terminals. For a fully charged battery, the output voltage of the comparator transitions from high to low and from low to high for indicating a fully discharged battery. When implemented with external hysteresis, thresholds can be pre-defined to yield the proper output states.

The comparators can be tiny-footprint devices with internal references, consuming very low quiescent currents. When large-value resistors are used in the circuit, the overall operating current will be comparable to the typical self-discharge rate of the battery. By designing the circuit to operate from a low supply voltage of about 1.7 V and consuming less than 2 µA of current, the circuit will be able to produce the proper output state even when the battery has only a minimum charge remaining.

The component values necessary to realize the application for battery state monitoring must be selected with care. The determined threshold value should provide a narrow band of hysteresis to allow for more cushion for component variation and tolerances. Using resistors with 0.5% makes the circuit work with ±1% accuracy.

What are Miniature Slide Guides?

Slide guides are industrial mechanical guides to reduce friction in linear motions. They use rolling elements, either hardened steel rollers or balls, moving along two raceways, with a stick-slip arrangement. This provides a smooth linear motion in either direction even when the load is heavy. Usually, slide guides carry their loads on one or more blocks or carriages riding on a rail. Instead of carrying loads, they can also guide other components, making sure they move smoothly and easily along the rail. The rail length depending on the required length of the application is usually made up of several straight sections. For some slide guides, the linear motion can be unlimited in distance, as the rolling elements travel in recirculating paths.

Since the guides are not powered, they cannot provide the drive to move the load. The force to move the load actually comes from a mechanism such as a linear actuator, lead screw, ball screw, or a belt-and-pulley arrangement. A limit switch or some other form of brake outfitted on the linear drive is necessary to stop the motion on a slide guide. Users may also use other stopping mechanisms such as end stoppers or a bumper pad may also be used to halt the motion.

Applications where the space and weight are both limited use miniature slide guides. Although these offer the same functionality and have the same form, miniature slide guides are limited to being only 25 mm in height, and 13 mm or less in width.

People call miniature slide guides with different names such as mini carriage on a profiled guide rail, or mini linear guides. Available in a range of sizes, the performance capabilities of mini slide guides scale with use.

For instance, a load carrying block may be as small as 6 X 12.9 mm, weigh as much as 0.8 gm., and ride on 100 mm rails carrying a load of 2.8 gm. The dynamic load rating for such small guides would be 0.21 kN.

On the other extreme, a block weighing 338 gm., with dimensions of 46 x 79.5 mm, may ride on 100 mm rails with a load of 209 gm. The dynamic load rating for such a large guide would be 12.4 kN. The top speed with which a mini slide guide typically moves is about 1.5 m per second.

Despite their compact size, mini slide guides direct their motion along a linear axis, much as their larger counterparts do. Their main advantage comes from the compact size, allowing them to be used in devices such as robots, medical devices, wafer-fabrication equipment, and hard-disc drives. The mini slide guides also use either balls or rollers as their friction reducing elements.

Mini slide guides use rolling ball elements made of stainless steel or carbon steel. They can support heavy loads and offer a long operational life. An all-stainless-steel construction is best suited for applications such as vacuum or clean rooms.

Mini slide guides that use roller or cylindrical elements offer lines of contact area rather than point contacts as balls do. This allows them to carry heavier loads than slide guides using rolling ball elements can.

Measuring Very High Currents

High currents, such as 500 Amps and above, are common nowadays. Industries regularly use equipment consuming high currents, and vehicle batteries experience very high currents for a short time during starting. With vehicles increasingly trending towards their electric versions, it is becoming necessary to be able to measure high currents with precision. Increasingly, it is increasingly becoming critical to monitor current consumed accurately for ensuring performance and long-term reliability.

Current sensing is necessary for essential operations such as battery monitoring, DC to DC converters, motor control, and so on. Device specification mainly defines the performance of any current sensor solution. This includes the efficiency, precision, linearity, bandwidth, or accuracy. However, for designers designing a system to satisfy all the requirements of the specifications can be a challenging task. One way to do this is to use a precision shunt, a shunt monitor, and a signal conditioner.

The ±500 A precision shunt-based current sensor design from Texas Instruments (TI) has an accuracy of 0.2% of full scale reading (FSR) over a huge temperature range of -40 to +125°C. Several applications such as motors and battery management systems require such precision current sensing. In general, these applications suffer from poor accuracy caused by shunt tolerances, temperature drift, and non-linearity. Shunt monitors such as INA240, and signal conditioners such as PGA400-Q1 from TI help to solve these problems.

The design from TI works on 48 V or 12 V battery management systems and is suitable for measuring ±500 A, with both high- and low-side current sensing. It accurately compensates for temperature and non-linearity to the second order with an algorithm. Furthermore, it offers protection against harness faults such as input/out signal protection, reverse polarity, and overvoltage. TI has protected its design from electromagnetic interference.

Several ways of measuring currents are available, and these include using magnetic saturation, magneto-resistance methods, Lorentz force law, Ohm’s law, Faraday’s induction law, and more. While each technology presents its own advantages and disadvantages, every customer has his or her own preference and place of use for the specific topology they prefer to choose.

The simplest and most common technology makes use of Ohm’s law, which this TI design also uses. When designing the system for measuring currents, essentially the designer must choose where the current is to be measured—high side or low side, the range of measurement, and whether the current is uni-polar or bi-directional. These parameters define the suitable topology and the design the designer must use. Most vehicle systems now prefer to use 48 V and this new trend implies the current sensor will have to measure a large span of range.

The method of measurement follows a simple process. The ±500 A current passes through the shunt whose resistance measure 100 µΩ. This causes a noticeable amount of voltage drop across the shunt. The current sense monitor INA240 measures this small amount of voltage and passes it on to the signal conditioner, PGA400-Q1. The delta-sigma ADC micro-controller inside PGA400-Q1 creates a ratio-metric voltage between 0.5 and 4.5 V using its linearity and compensation algorithms.

Let the Raspberry Pi Monitor Energy

If you are looking for monitoring energy remotely, an open source system that uses the ever-popular single board computer, the Raspberry Pi (RBPi) may be suitable. The company, OpenEnergyMonitor, makes the open-source tools for monitoring energy, and at present, they are using the RBPi3. According to their co-founder Glyn Hudson, the aim of OpenEnergyMonitor is to help people understand and relate to how they use energy from their energy systems, and the challenges of sustainable energy.

The system uses five main units. Users can assemble and configure these to work in a variety of applications. Both hardware and software in the system is fully open-source, and the hardware is based on Arduino and RBPi platforms. Users can opt to use the system for monitoring home energy, monitoring solar PV, and or monitoring temperature and humidity.

emonPi

When configuring the OpenEnergyMonitor system, emonPi, as a simple home energy monitoring system, it allows measuring the daily energy consumption and analyzing real-time power use. The all-in-one energy-monitoring unit, emonPi is a simple installation based on the RBPi, requiring only an Ethernet or Wi-Fi connection at the meter location.

Clip-on CT sensors on the emonPi enable it to monitor independently two single-phase AC circuits simultaneously. While the emonPi can monitor temperature, it has an optical pulse sensor to interface directly with the utility meters, which means the emonPi has to be installed next to the utility meter.

The emonPi comes with Emoncms, the open-source web application. This helps in logging and visualizing energy use along with other environmental data such as temperature and humidity. It has two power outlets and requires Ethernet or Wi-Fi to transfer data. The RBPi operates on a pre-built OS on an SD card included with the energy monitor. The 5 VDC power required has to be fed in from an external power supply unit.

As power is the product of voltage and current, the emonPi requires an AC-AC voltage sensor adaptor and a clip-on CT sensor. While the emonPi comes with one CT sensor as standard, it can accept two CT sensors.

emonTx

For remote monitoring, users can use emonTx, a remote sensor node as an alternative to emonPi. The emonTx runs as a standalone unit, with an ESP8266 Wi-Fi module running EmonESP. This can post directly to Emoncms without using emonPi or emonBase.

Users can monitor a maximum of four single-phase AC circuits with the clip-on CT sensors using the emonTx. A plug-in AC-AC adaptor powers the unit, and provides the AC voltage sample, which the emonTx uses for real-time power calculations. If AC power is not available, emonTx can be powered using four AA type batteries.

Optional LED Pulse Sensor for Utility Meter

This sensor allows interfacing directly with utility meters that have LED pulse output. It is compatible with emonTx and emonPi, and reports the exact amount of energy as the utility meter does. Although best used together with clip-on CT sensors, the LED pulse sensor cannot measure instantaneous power.

emonBase

This is a web-connected gateway, consisting of an RBPi and RFM69Pi RF receiver board. It receives data via a low power RF carrier at 433 MHz from emonTx or emonTH and offers local and remote data logging using Emoncms.

Are Pin and Sleeve Connectors Better?

Most people in the US are familiar with the twist lock cable connectors, as these are the NEMA standard. In Europe, there is another advanced cable connector—the pin and sleeve connector—but it is not so very well known in the United States.

In short, pin and sleeve connectors deliver power through sealed connections, while insulating the connections from moisture, grime, and chemicals, which makes them suitable for applications under abusive environments. Their design is such as to prevent them from being disconnected under load. Pin and sleeve devices come in varying designs, ranging from metal-housed types to high impact-resistant plastic ones.

Whether specifying mobile power solutions on the factory floor, designing machines for international customers, or planning outdoor power distribution systems, pin and sleeve connectors with mechanical interlock switches are a cost-effective and safe option to all wiring requirements.

Well-suited for supplying power, these male-female connections can deliver power to a wide range of equipment such as lighting, portable tools, conveyors, compressors, motor generator sets, and welders. They are also good for matching the right equipment with high-current power sources, while integrating fused and switched interlocking receptacles in wet or corrosive environments.

When compared to the standard twist lock, pin and sleeve connectors offer plenty of other benefits. While their click-lock housing makes assembly fast and easy, their rugged design makes them highly durable. In contrast to male NEMA plugs leaving their pins exposed to the environment, a shroud surrounds the male plugs of a pin and sleeve connector and protects the contact pins.

With more configuration options for pin and sleeve connectors in the market than available for twist lock, they are color-coded to different amps, from 20 to 100 in the US. On the other hand, there is no color-coding for NEMA twist lock sockets.

Whereas twist lock sockets offer IP protection only as an option and with a higher price, this is a standard feature of the pin and sleeve connectors. While twist lock sockets are available only in the markets of North America, options of North American along with International versions are common for the pin and sleeve connectors.

Conforming to IEC 60309, one of the most appealing reasons for using the pin and sleeve connector is their built-in safety features, designed to make the connectors safe for both, the operators and the application.

IEC 60309 focuses on operator safety for a family of connectors for use in equipment in domestic as well as international markets. Products intended to be compliant with IEC 60309 must meet global standards, regardless of the origin country or the manufacturer. The standard specifies five devices—mechanical interlock switch receptacles, inlets, receptacles, connectors, and plugs.

Every pin and sleeve design is unique with respect to the design voltage. That means there is no possibility that a wrong voltage will be accidentally used in the application. Moreover, the design of plugs prevents them from being inserted into the wrong outlet type.

An additional safety feature is the pilot pin included in the electrical interlock systems. The pilot pin contact disconnects before all other connections do, signaling the electrical interlock to shut off the power.

A Soundcard HAT for the Raspberry Pi

If you have been wondering how to use the popular Raspberry Pi (RBPi) single board computer for effects to be used with musical instruments such as the guitar, the Pisound board from Blokas may be the answer. With the Pisound board, any musician can connect any type of audio gear to the RBPi, and bring their project to an entirely new level. Pisound is a soundcard HAT for the RBPi.

HAT is an acronym for Hardware Attached on Top of an RBPi. HAT boards have an EEPROM that tells the RBPi the values of its variables specific to the device on the board. The HAT board will also have a GPIO connector to match with that on the RBPi, so that when plugged in, the HAT will sit atop the RBPi.

The Pisound HAT for the RBPi3 acts as a high-technology sound card. Not only does it allow sending and receiving audio signals from its jacks, but it can also send MIDI input and output signals to compatible devices. On board the card are two 6 mm input and output jacks, two standard DIN-5 MIDI input/output sockets, potentiometers for gain and volume, and a button for activating patches of manipulating audio. The Indiegogo campaign has given the Pisound board an incredibly successful start.

The Pisound website offers excellent documentation, making it a simple affair to set up the board. First, you have to mount the board atop your RBPi, matching the GPIO pins, and securing it with screws. Next, download and install a fresh installation of the Raspbian OS and set up the software according to instructions from the website. The only thing that remains now is to connect the instrument and create patches for Pure Data. This is a popular visual programming interface to manipulate media streams.

The possibilities with Pisound are endless. For instance, you can create simple fuzz, delay, and tremolo guitar effects. Limited only by your imagination, you could come up with endless ideas.

For example, the guitar effects could go into a web interface, accessible over a local network on a tablet or smartphone. On the other hand, with the characteristics of the guitar signals, you could control an interactive light show or project visualization on the stage. One of the advantages of the Pisound is you can use the audio input stream basically to generate other non-audio activities.

The compact and practical size of the project makes it convenient for embedding it within one of your instruments say the guitar. However, it is always possible to design and fabricate a custom enclosure for the board and the RBPi.

Sonic Pi, a musical community favorite, has also pledged to support the board very soon. That means even if you do not own a musical instrument, or play one, you can still make awesome sound effects with this clever little HAT.

You can load patches from Pure Data using a USB key. The button on the card makes it easier to interface with the RBPi. Moreover, it you are familiar with Automatonism, it will be easier for playing with the Pisound just as if it were a modular synthesizer.

What are Digital Circuit Breakers?

We need protection from fires resulting from an electrical overload caused by a faulty device or an accidental short circuit. The huge current from the overload heats up wires and their insulation may go up in flames. There are several ways to activate this protection.

The oldest method consists of a fuse wire. Usually, this is a thin wire enclosed in a casing. The material of the fuse wire is carefully chosen to heat up and melt (blow) when a certain current level is exceeded. Melting of the wire disconnects the circuit and interrupts the current, preventing heat buildup. Once a fuse wire blows, it has to be replaced by a similar wire to continue protection and reestablish electrical operation.

Nowadays, it is common to see switchboards where the fuse holder has been replaced by a miniature circuit breaker (MCB). The device has a bi-metallic spring holding pair of mechanical contacts, which can establish connection by throwing an external switch. An electrical overload causes the bi-metallic spring to trip and the contacts open up, disconnecting the fault from the rest of the circuit. Once the fault has been cleared up, the MCB can simply be rearmed by flipping the external switch.

Although simpler to operated compared to the fuse wire, MCBs have their own disadvantages of being slow to react and expensive, with their cost going up proportional to their trip current. Over time, the bimetallic strip tends to deform, reducing the current capacity of the breaker and its accuracy. The mechanical construction of an MCB makes it prone to wear and tear.

Opening mechanical contacts to interrupt high currents often causes an arc flash to jump across the contacts. It is necessary to quench the arc flash within a short time to prevent incidence of fires.

For overcoming the above problems, using a digital circuit breaker offers the most convenient solution. The device has an all-electronic construction involving an electronically controlled automatic switch. There are no mechanical components involved, no bi-metallic strips, and no electromagnetic coils inside.

Atom Power is proposing a solid-state digital circuit breaker to replace the traditional types and thereby avoiding the related problems. Currently awaiting approval from the Underwriters Laboratory (UL), Atom Power has two models, one each for AC and DC circuits.

So far, Atom Power was producing only a few numbers of their digital circuit breakers, using their in-house 3-D printers for producing the plastic parts of the housing. With increase in production, they will use the resources of an external rapid manufacturing company, and will move to injection molding for higher volumes of commercial operations.

The Atom Switch, within the breaker, responds to a digital signal generated whenever the current exceeds a certain level, whether due to overload or short-circuits. With tripping speeds exceeding 16,000 times those of its mechanical counterparts, the arc flashes simply do not happen.

Another technique used to prevent arc flashes is to switch the device off when the AC voltage passes through zero. This is called zero voltage switching or ZVS, and is a very useful technique to prevent arcing across the open ends of the circuit.

Peltier Cell Generates Electricity from a Lamp

The early 20th century saw the end of the use of candles and oil lamps as electric lighting became more common. Earlier, candles were made from various items such as natural fat, wax, and tallow. However, most manufacturers make candles from paraffin wax, a substance obtained from refining petroleum.

Compared to an incandescent bulb, a candle produces nearly a hundred times lower luminous efficacy. The luminous efficacy of a modern candle is about 0.16 lumens per watt, and it produces nearly 80 W of heat energy. Another form of the candle, tea lights, come with a smaller wick and produce a smaller flame. However, a standard tea light produces about 32 W, depending on the wax it uses.

The Peltier cell makes it possible to convert a small fraction of the heat energy from tea light into electricity. This can be used to drive a highly efficient LED light. This arrangement helps to boost the total luminous efficacy of the tea light and we can get a larger amount of light.

The Peltier element is really a solid-state active heat pump. Electricity applied to the element causes it to transfer heat from one side of the device to the other. Therefore, a Peltier element can be used for heating or cooling. If one side of the Peltier element is heated to a temperature higher than that on the other side, the Peltier element works in reverse, generating a difference of voltage between the terminals. This reverse effect is known as the Seebeck effect and the device works as a thermoelectric generator.

As the efficiency of a typical thermoelectric generator is only around 5-8%, the heat from a tea light should be capable of generating about 1.6-2.56 W of electrical power from the Peltier element. In practice, the Peltier element gives only about 0.25 W with the heat from the tea lamp. The reason being the inability of the Peltier element to capture the entire heat produced by the tea lamp to generate electricity—some heat is lost in transmission, and some in heating up the Peltier element. However, the energy generated by the Peltier acting as a thermoelectric generator is capable of running a small fan and drive an LED lamp satisfactorily.

A thermoelectric generator can be built around two 40×40 mm TEC1-12706 Peltier elements, mounted between two heat sinks, and connected in series to boost the voltage output. The smaller heat sink at the bottom serves to spread the heat from the tea light to heat up the Peltier elements evenly. The larger heat sink at the top has a fan to cool it and maximize the temperature difference between the two sides of the Peltier elements.

Although the fan draws power from the Peltier elements, it also helps to improve the efficiency of the system and make more energy available for the LED light. The fan also helps to keep the Peltier elements from overheating. Peltier elements are internally soldered with a bismuth allow solder melting at 138°C. Therefore, no Peltier element should operate above this temperature.

RF Transistors using more Germanium

So far, gallium arsenide was the choice of material for building fast radio frequency transistors. However, that scenario is changing fast. Germanium is fast catching up, as it is less expensive and more compatible with CMOS and silicon. In this connection, the European research institute Imec has presented a pair of papers featuring gate-all-around (GAA) transistors at the 2017 Symposia on VLSI Technology and Circuits in Japan. They claim that GAA transistors can outperform standard CMOS below the 10-nm node, while featuring source/drain contacts with resistances of the order of a billionth-of-an-ohm.

Imec claims their SiGe GAA FETs are super-fast, as they use scaled strained germanium p-channels. With diameters below the 10-nm range, the GAA FETs are integrated on a 300 mm platform, which gives them their superior electrostatic control. They achieve this by using high-pressure annealing (HPA)—the same technology used by Imec for their more traditional FinFET architecture.

According to Imec, they used pulsed-laser annealing and shallow gallium implantation techniques to achieve the very low source/drain resistivity. They claim to have achieved a new world record for resistances of one billionth of an ohm for the source/drain contacts of their p-MOS transistor.

That germanium-on-silicon transistors have the ability to outperform other technologies as radio frequency transceivers is already well known. In practice, this allows using the same CMOS technology throughout the transceiver and avoids using GaAs Pas, which has lattice structures incompatible to silicon.

However, beyond the 10 nm range of advanced nodes, there was no confirmation that SiGe could perform as well for FinFETs or for more advanced architectures such as the GAA FETs, least of all in the state-of-the-art wafers of 300 mm. According to Imec, using HPA, they were able to boost the performance and electrostatic control exceptionally for both p-channel FinFETs and GAAS.

Imec will be sharing their record-breaking billionth of an ohm per square centimeter for P-SiGe source/drain contacts with other CMOS members, namely, TSMC, Sony Semiconductor Solutions, SK Hynix, Samsung, Qualcom, Micron, Intel, Huawei, and GlobalFoundries.

Imec claims to have made it easier to go below the 10-nm range without sacrificing electrostatic control, by making architectural changes they have not yet disclosed. This allowed them to compensate for the smaller bandgap and larger permittivity of SiGe. According to Imec, this has also allowed them to make gate lengths of the order of 40 nm, and nanowires of about 9 nm, the shortest and the thinnest in the world. As a consequence, they claim to have lowered the sub-threshold slope of 79 mV/decade and the drain-induced barrier of 30 mV/V, while retaining the electrostatic control for their GAA-FETs.

By using HPA techniques, Imec is also claiming to have boosted the performance of both their germanium GAAs and FinFETs. Because of HPA at 450°C, Imec researchers were able to improve hole mobility and interface quality to 60 cm2/Vs. By optimizing the HPA technique, they could improve the electrostatic and overall performance of the GAA devices significantly. This allowed them to reach 60 nm lengths and achieve a Q-factor of 15. They were also able to lower the currents from 3 to 10-billionths of an amp per micron.

How to Simulate the Raspberry Pi?

You may have an urgent project that requires the use of a Raspberry Pi (RBPi), but do not have immediate access to a physical kit or the SBC. However, that should not hamper your progress with the project, as Microsoft is now offering an online RBPi simulator. The online RBPi simulator allows users to write code for controlling emulated hardware. Therefore, for the present, users can interact with a sensor to collect data from it and control an LED.

On the simulator, the user has a graphic of an RBPi wired on a breadboard to a combined humidity, temperature, and pressure sensor, along with a red LED. On a side panel, the user can enter JavaScript code as Node.js, with which, they can control the LED while collecting dummy data from the simulated sensor. A command line at the base of the panel allows execution of the code.

When loaded, the simulator starts with a sample program, which the user can use to collect temperature from the sensor and display it on the command line. Tutorials are available from Microsoft on running this code, and for this, the user has to first sign into Microsoft’s Azure IoT Hub, and select the free tier service option. Microsoft has designed the simulator to be compatible with a real RBPi. Therefore, anyone can test their code for controlling hardware using the RBPi, before they are ready to transfer their code it to a real device.

According to a Microsoft employee, Xin Shi, the simulator is presently in preview, offering only basic functionality. That means the embedded image of the RBPi is static, allowing only a limited interaction with the sensor and the LED. There are plans for emulating new devices and sensors, but there is no timeline. Moreover, the simulator’s code being open-source, anyone is free to work on expanding the simulator.

However, this is not the first time a simulator has been designed for simulating RBPi controlled hardware. Working with the US startup Trinket, the Raspberry Pi Foundation had created a web-based emulator for Sense HAT. This is an RBPi compatible add-on board bundled with several sensors, a joystick, and a matrix of LEDs.

Just as the Microsoft simulator does, the emulator for the Sense HAT also allows users to work with Python codes for interacting with the add-on board. Compared to the Microsoft simulator, the emulator from the Foundation offers users a greater number of sensors to interact with, and allows the user to have more control over the simulated version of the LED matrix on the board.

On the website, users have a choice of four Python programs. The first one allows selecting temperature, pressure, or humidity sensors, and manipulating the sliders to change the readout of the LEDs. The second is a game of rock, paper, and scissors, which the users can play using arrow keys to select while competing against the RBPi. The third is another game where a small bird has to fly through obstacles, and the fourth is a game of Astro Bug, which has to eat the food, while avoiding enemies.