Monthly Archives: July 2014

PicoBorg Helps To Build a DoodleBorg

Imagine a small tank driven by a Raspberry Pi or RBPi. This is the DoodleBorg, a two-horsepower goliath and is the most powerful robot controlled by the RBPi. Powered by starter motors originally from a motorcycle, the DoodleBorg uses six PicoBorg motor boards made by PiBorg.

The DoodleBorg uses a tiny, credit card sized single board computer, the RBPi, as its brain. It has six reverse motor controller boards or PicoBorgs controlling its six wheels. Each of the boards is capable of handling 10A on average. Therefore, with two batteries in series, the average power output is 6x10x24=1440Watts or roughly 2HP. Peak power outputs are higher, about 2.1KW or three horsepower. Usually, the RBPi is prominently visible in the robot it is powering. However, in this case, you will hardly recognize it in the massive size of the project. Commands to the DoodleBorg are sent via a PS3 controller.

The PicoBorg reverse motor controller cards were specifically chosen for this project. These are advanced dual motor control boards for use with an RBPi. PicoBorgs can control big or small motors, with forward or reverse speed control. Each board, with its own emergency power off, is sized to mount on your RBPi for PID control and feedback via the GPIO pins. If you need to control more motors, simply plug in more boards and control up to 200 motors.

The dual motor controllers can handle input voltages between 6 and 25VDC and control up to 5A per channel, that is, 10A when combined. The emergency power off switch works in both bidirectional and speed control modes. PicoBorg boards are capable of handling two DC motors or one stepper motor with 4- or 6-wire configuration. For communication, you can use the I2C or SCK/SDA pins on the GPIO together with 3V3/GND pins. Adding the PicKit2 brings additional functionality.

PicoBorg reverse motor controllers are protected against overheat, short circuits on all outputs and under-voltage lockout. Connections are very straightforward. Six screw-terminals on the board allow connecting two motors and a battery. There are two 6-pin terminals, one of which is for connecting to control signals from the GPIO of the RBPi. The other 6-pin terminal can be used for daisy chaining another PicoBorg board.

Another connector on the board allows you to easily add a normally closed switch to act as an emergency switch. In case of any fault, simple open the switch and the motor will be cut off. The software on the PIC micro-controller on board will recognize the emergency switch operation and prevent further operation of the motors until enabled by a software command.

Another feature of the PicoBorg is its ability to run DC motors with taco feedback. The software accepts taco input signals that indicate either the number of rotations or the distance traveled by the wheels. Acceptable feedback signals are – quadrature signal (A or B) from an encoder, taco signal from a computer fan motor, index mark feedback such as one per revolution pulse. The motor connection remains the same as that for a standard DC motor setup.

The Eavesdropping LED Street Lights of Las Vegas

LEDs have come into our daily lives almost without our noticing them and suddenly they are everywhere. People visiting Las Vegas may notice that streetlights there are LED based. That in itself may not be very surprising, except that the LED streetlights in Las Vegas are able to not only entertain with videos and music, they care about what you say. Furthermore, LED lights even watch while you speak your thoughts. That gives credence to the inevitable quip: “What happens in Vegas doesn’t stay in Vegas.”

Las Vegas streetlights are acquiring modules named Intellistreets from a company in Michigan – Illuminating Concepts. The modules will deliver music and news for the entertainment of the passers-by. However, they can also eavesdrop.

LED streetlights are nothing new – New York has a retrofit project. Las Vegas, along with some other cities, made the switch several years ago. However, adding the power of vision and hearing to streetlights is something entirely out of the ordinary. A fascinated San Francisco is also mulling over something similar for its streetlights.

Depending on whether the application is a retrofit or entirely new, Intellistreets has a number of configurations. For Las Vegas, it is a retrofit application, where post-top modules are added to the existing streetlights. The audio and video from the streetlight is transmitted wirelessly to the public works department.

Lights that double up for watching have been around for a while. The oldest patent for such an activity was issued in 1973, for a 360-degree infrared surveillance along with a panoramic display. Others have offered designs of a fake surveillance camera, attempting to create the illusion of tracking with a flashing LED.

Privacy cultures vary in Europe and the US. While closed-circuit video systems are the norm in say, UK and accepted there, suspicion of the government in the US is more deep-seated and video surveillance is less welcome, whatever may be the type.

Therefore, organizations such as municipalities that intend to deploy video surveillance use equipment with IP networks for collecting video data and communicating with the devices. However, it is not so easy or cheap as it looks offhand. Although optical fibers do provide the highest capacity, installation of fiber-optic cables can be rather expensive. Instead, Intellistreets uses cellular or wired connectivity between collection servers and light poles. They have found that for adding to an existing lighting infrastructure, going wireless is the easiest.

According to reports, the surveillance business of Illuminating Concepts started with an indirect path. Its CEO Ron Harwood has a passion for music. Majoring in ethnomusicology at Wayne State and managing Sippie Wallace, Ron made his way into lighting systems on the strength of his liaison with the entertainment industry.

Harwood holds two patents. One of them is for the combination of a lighting and a media device, with the device being self-powered based on the movement of air through the unit. Illuminating Concepts carried the idea forward, adding two-way communication. This gave the streetlight the ability to produce a disembodied voice that offered to help lost visitors.

An Exquisite Raspberry Pi Enclosure

There are countless types of enclosures available for the inexpensive credit card sized Single Board Computer – the Raspberry Pi, popularly known as the RBPi. All have their unique capabilities and advantages. Some are made of wood, some of paper while most others are made of plastic.

The molded enclosure from Hammond Electronics is specifically designed to house the RBPi model B. The exquisitely molded container is shaped like a book and is available in black, grey and translucent blue. The stylishly rounded design has apertures for all the IO interfaces and accessories supported by the RBPi. The enclosure is actually two parts made to fit one on top of the other, holding the RBPi between them. No screw-fixings are involved, and a specific sequence is required to get the bottom, the RBPi and the top fitted together perfectly.

On opening the 1593HAMPI enclosure assembly, you will notice the bottom half has some stationary clips on its inside. Holding the bottom half in your palm, slide the RBPi board in at an angle against these stationary clips. Once in place, push down firmly on the RCA jack of the RBPi, until you hear the board click into position. Now the RBPI is securely held in the bottom part of the enclosure.

Take the top part of the enclosure and touch its rounded ends to the corresponding rounded ends of the bottom part, on an angle. Still holding the bottom part firmly, push down on the outer edge of the top part, until you hear a snapping sound. On turning the assembly around, you will see a clip from the top part jutting through an opening on the bottom part. This holds both the halves together. In case you would like to separate the two parts of the enclosure, simply pull back the clip from the bottom part and the two halves will come apart.

Hammond Electronics offers self-adhesive rubber feet, which you can fit in the circles on the bottom part of the enclosure. They will prevent the encased RBPi from sliding off. One of the most popular accessories of the RBPi is the camera module. You have a choice of two methods for mounting the camera module. Screw the camera to the inside of the top part, which has a hole provided for the lens. However, if the camera must remain outside the enclosure, you can fit it through a slot in the top. The camera will now be standing at right angles to the assembly.

Access to the GPIO header is provided through a cutout on the mating line between the top and the bottom halves. The sides also have apertures of the right size and shape for all the ports. Therefore, you can easily access the HDMI interface, the micro-USB power-in connector, the RCA ports for audio and video, the SD card, the RJ45 LAN and the two USB ports. The base has two captive slots so that you can attach the enclosure to a surface. For stand-alone applications, the rubber feet are helpful.

Meet the Prettier Raspberry Pi Model B+

Just as soon as you thought you knew as much as there is to know about the most popular single board computer, the tiny versatile Raspberry Pi or the RBPi, acquaint yourself to a prettier cousin. There is an update to the familiar RBPi Model B and it is called the RBPi Model B+. Raspberry Pi Foundation, the manufacturers of the RBPi, have incorporated several improvements requested by users in the new model.

Although the RBPi Model B+ retains the same controller, has the same amount of RAM and runs on the same software as the Model B, there have been several cosmetic changes. The most notable improvements in RBPi Model B+ are:

— GPIO has 40 pins; the first 26 pins retain their pinout as in Model B.
— Four USB 2.0 ports with better hot plugging and overcurrent behavior; Model B has 2 ports
— A micro SD socket (push-push type); Model B has SD card socket of friction-fit type
— Power consumption 0.5-1.0W; Model B power consumption 0.55-1.65 W
— Better audio with separate low-noise power supply
— Improved form factor. Compared to Model B, the USB connectors align with the board edge and composite video moved to the 3.5 mm jack. Model B+ has four mounting holes.

Even with all the above improvements, the price of the RBPi Model B+ has been retained at $35. So what happens to the Model B now? According to the Raspberry Pi Foundation, Model B will remain in production as long as demand for it continues.

In its lifetime of two years, the RBPi SBC has gone to many places such as floating in space, deep under the sea and controlled complex machinery. Considering that the initial goal of the project was to educate children in Computer Science, RBPi has definitely marked a place of its own. RBPi has revolutionized the landscape of education for children and adults alike. People have learnt more about Computing and Electronics with RBPi.

Since the RBPi B+ model has the same architecture as the earlier Model B, the Foundation assures compatibility with the existing projects and software developed so far. According to the feedback received from the community, RBPi Model B+ is a more refined product.

Measuring 85x56x17mm in size, the RBPi B+ is slightly smaller than the form factor you are accustomed to with the Model B. Additionally, an improved layout backs up the size reduction. The organization of the board is neater and there are several improvements.

For example, there are now four USB ports as opposed to the two earlier. This is because the RBPi Model B+ uses the new LAN9514 chip. The Model B had its ports dotted all around the perimeter of the board. In contrast, the Model B+ has concentrated its ports only on two sides. The RBPi Model B+ with its four USB 2.0 ports supporting higher currents can now attach external portable USB2 hard drives. For those who had to counter the USB reboot issue on the Model B, can now rejoice since RBPi Model B+ has more stable USB hot swapping of USB devices.

Is SMT Good for Precision Resistors?

Where precision resistors are concerned, a small size may not always be the perfect answer and SMT has its trade-offs. Power density in surface-mount chip resistors is higher than in through-hole parts, which results in chip resistors running hotter. Surface area in the case of through-hole resistors is higher, allowing them to dissipate internal heat to the surrounding air, while SMT devices mostly dissipate through the PCB. That leads to heat build-up in the system, affecting all the components. Due to this excess heat, long-term stability of resistors is degraded, especially when operating at higher temperatures.

Configuration considerations also affect SMT components. The length vs. width of the chip is an important parameter. If this aspect ratio is beyond a limit prescribed by reliability studies, generally ~2:1, board flex stresses may cause the chip to de-laminate from the board or to crack. Widening the chip does not help to eliminate the stress – rather that makes it harder to remove solvents and resins from under the chip.

Therefore, the best choice of a resistor for high-precision application would be one specifically designed to provide higher resistance value, dissipate higher power, be available in tighter tolerances and provide better long-term stability. It must also use less board space and allow easier cleaning of resins and solvents. All this is possible when precision resistors are configured in metal hermetic cans or in molded rectangular blocks, with through-hole leads extending from the bottom surface. The construction also prevents the resistor from being subject to thermo-mechanic stresses from the PCB.

Such constructions, which include stand-offs, allow reliable cleaning from under the component and the approach also minimizes the required board space. However, on some occasions, the only option available for design is to use an SMT. In such cases, using a surface-mount device with flexible terminations will be most useful.

The main idea behind use of SMTs is miniaturization. However, a tightly packed board may not always be a good idea, specifically for precision applications. For example, a mounted resistive element placed parallel to the PCB is susceptible to vibrational movement, resulting in parasitic microphonic noise. This is one reason designers do not prefer using SMT components in the feedback path of circuits. A better choice here would be to use vertically oriented through-hole parts. The legs help to absorb the deflections from the PCB.

For a precision resistor to remain stable over long periods, its temperature must remain within limits specified by the manufacturer. Heat from adjacent components and changes in the ambient temperatures affect the stability. This is defined by the TCR or temperature coefficient of resistance. Self-heating (because of load), is another factor and this is defined by the Power TCR or power coefficient of resistance.

Specific equipment such as medical instrumentation using precision resistors is highly dependent on these performance characteristics. Designers prefer to use Bulk Metal Foil resistors to deliver proven stability and reliability performance. Bulk Metal Foil resistors perform superbly even when exposed to unstable levels of humidity and temperature including other harsh environmental conditions. Foil resistors also feature non-capacitive and non-inductive designs.

What do Certified Ethical Hackers do?

To know the taste of a specific food item, you have to put it in your mouth. To know how durable an item is, you need to subject it to a battery of tests and then compute its MTBF. As industry moves from traditional devices to using more modern, connected devices and systems that are always on, security is seen as a major obsession.

People need to know how secure their network is against external attacks. However, just as an arch can withstand a good amount of external load, but crumbles easily against an internally applied pressure, so can networks. Some of the biggest security threats faced by networks unwittingly comes from people on the inside and not from those who are outside the network.

Companies employ a Certified Ethical Hacker to hack into their networks in an attempt to expose security weaknesses that they might have overlooked while securing their network. A company may have several external infrastructures – VPN access points, email servers, domain name servers, web servers, perimeter firewalls and other applications – accessible publicly from the internet. Typically, this is where the Certified Ethical Hacker starts his work.

The hacker has several tools to help him in his task. They include password crackers, keystroke loggers, eavesdropping, denial-of-service, sniffers and remote controls. In fact, hackers usually employ powerful digital tools akin to an expert lock-picker’s toolkit and they use these to attack the firewall systems.

Most companies take great care to make their networks impenetrable against external attacks. Therefore, it is no surprise to hackers if they are unable to get in. However, these same companies often overlook insider threats. Hackers can expose these vulnerabilities, especially, people working on the inside. This depends on a very simple fact – most people’s response is highly predictable when they are placed in a particular situation.

For example, consider what someone will do with an unclaimed innocent-looking USB flash drive lying on the toilet paper holder in the company’s washroom. That’s right, 90% of those finding the USB key will want to know what it contains and plug it into their computer to find out!

Now, a hacker may have knowingly planted a computer program on the flash drive that would auto-run and execute a remote connection to his computer as soon as someone operated the drive. That would give the hacker instant access to the company’s network. The program would take the computer owner’s encrypted credentials and pass them to the company’s own server, thus mimicking a normal and real login.

Once the hacker is able to log into the network of the company, he can unleash any amount of mayhem. He can extract usernames and passwords, open and interact with any file on the compromised system and even take screenshots of current activities on the desktop of the user.

The Certified Ethical Hacker will report his findings to the company management about how easy or difficult he found it to hack into the company’s network. This highlights the fact that security is not just about the protection of the firewall of the network. Even when there are no disgruntled employees, internal threats can be real.

What is a diskless computing system?

Today’s data centers and Hybrid Compute Clusters or HPC work with thousands of computers. With every computer having its own operating system, even a team of highly skilled administrators would find it hard to keep up with the demands required for maintaining each system. Typically, admins strain to keep the myriad types of computers they have, all functioning, as they should. Sysadmins must duplicate their efforts over and over, as they install new systems with new system software and handle configuration problems individually as they arise on each of the various systems. However, things need not always be so complicated and difficult.

There can be an alternative scenario, where all that the admins must do is reboot a machine for it to enter into a pre-configured operational environment. Such operational environments or images, as they are called, can exist in multiple numbers with each image acting as an individual container for the system software, configuration and behavior of the group of nodes the image was designed to run on.

For example, a specific image managing the operational requirements of a large multi-user cluster, would contain the necessary software, its configuration, including the behavior of compute nodes, admin nodes, login nodes, IO nodes and anything else needed. A second image might be based on the latest Linux distribution that is currently under test for a future deployment. Images could be configured to handle web servers, database programs, application servers, user desktops or render farms.

With one root image controlling the behavior of all machines, the complexity of the overall system and the overhead of system administration are scaled down drastically. It also leads to a stable environment as administrators can focus on hardening only one system instead of spreading their attention thin across the various setups.

In such a cluster, individual computers are typically devoid of hard disks, although with-disk computers are also supported. Diskless computers can be any subset of nodes and may be booted into any image as required. When an image is changed, all the nodes see it simultaneously. Only a reboot is what it takes to interchange a system image. Moreover, an image may be cloned with only a simple copy. Any number of functionally different machines may use the same image, with a simple synchronization propagating a working modification made to one system to all other systems. Since the image remains the same no matter which machine is using it, the behavior of each configured node remains the same.

Local networks may have many nodes with the image being cloned for each of them, with each clone being capable of serving the image to as many diskless clients as the network or the machine is capable of handling. The nodes operate normally using the configuration designed, which determine their role at boot time. The functional role of any node can be changed on the fly, once the node has booted.

An open-source software package, oneSIS, offers such a method for building and maintaining compute systems of any size. The lightweight, easy to configure and flexible package reduces the cost of cluster administration drastically.

What is the difference between Linux and Android

Those of you who use the Linux OS on their desktops know that it is vastly different from the Android OS typically used on the mobile phone or tablet. One of the glaring differences one notices in the two OSs is that Android is geared heavily towards the touch operation, whereas Linux is limited to operations with a keyboard and mouse. However, both operating systems have a common origin and share the same kernel.

Linux can be best defined as an operating system suitable for running on a fixed or limited function device – for example, embedded Linux on a smart refrigerator or toaster. This allows the device to take full advantage of the massive processing power of Linux and utilize the peripherals to the utmost. When used on a fixed function device, embedded Linux has unparalleled operating efficiency and performance, uses minimum memory footprint and power, while providing the user with the utmost ease in using the device for its intended purpose.

Smartphones and tablets, although embedded devices, are definitely not fixed-function (different models with myriad functionality). The sheer volume of these devices tends to skew the traditional definition of embedded Linux. With increase in the capabilities of the hardware, the definition of embedded Linux also undergoes a change, especially where limitations in storage and processor capabilities are concerned.

On the other hand, Android, although a desktop-like Linux mobile OS and platform, allows users (manufacturers) to define their own usage patterns. It also allows vendors to update and upgrade the platform dynamically. However, some applications blur the distinction between Android and embedded Linux.

One of the examples of this type of application can be seen in the television set-top box. This used to be a fixed function device running on embedded Linux. With the increase in functionality and dynamism of the TV, the set-top box now has app downloads and software upgrades similar to Android devices. Moreover, Android is undergoing changes similar to what embedded Linux is facing. It is growing beyond being just a tablet operating system or a mobile communication system.

What many people do not know is Android and Linux both use the same kernel. However, Android focuses on the vertical integration of its user space components with the Linux kernel itself. In most respects, Android can be seen as another flavor of embedded Linux – just as each embedded Linux is tailored to the architecture of the CPU, peripherals, SoC support and purpose of the device it is expected to run on.

The specialty of Android lies in its ability to be customized and optimized, yet maintaining common components and standardized APIs. This allows the environment of application development to be more consistent. Of course, that also means the Android core images have a very large footprint to maintain this consistency or standardization. Additionally, this increases the surface for vulnerability profiles.

With Android, you have a large amount of functionality. Of late, some of the leading developments for supporting new graphic accelerators and SoCs appear first in Android environment. They are then pushed upstream to the other projects involving the Linux kernel.

Talk To Your Raspberry Pi through an FTDI Breakout Board

You do not really need a monitor and a keyboard for logging into the tiny credit card sized single board computer, the famous Raspberry Pi or RBPi; there are several ways to do that. One of the very simple ways is to listen in on two of the serial communication monitoring pins on the GPIO header of the RBPi.

Manufacturers of most computers have now given up on including serial ports on their products in favor of the more Universal Serial Bus or USB. However, connecting the serial pins on the RBPi to the USB port on the computer is not so straightforward. A special translator is required, one that understands and converts between the serial and USB protocols.

FTDI makes a special cable with an FT232 chip in between that can help to connect the serial port pins on the RBPi to the USB port of the computer and provide meaningful communication between the two. Modern Devices have gone one step further. Instead of having to deal with connectors or soldering on the RBPi side, they have designed a breakout board with the FT232 on it. The FT232 TTL signals are available on a header, which is suitable for plugging into the GPIO header on the RBPi; this is the USB BUB 1,

On one side of the BUB is an FTDI header, a six-pin version very common with most of the Arduino-compatible boards. The breakout area of the BUB is very handy as it allows you to reconfigure the signals to any of the pins on the second header. When you have to connect different devices such as the Parallax Propeller, this rerouting is very useful, as pinouts or the RBPi and the Parallax Propeller are different. The rerouting process also allows you to select the proper logic level (5V or 3.3V) for your device with a single jumper. You can suitably modify the breakout area of the BUB to enable it to connect appropriately to two different style devices without resoldering the connections.

When connecting to the RBPi, make sure you are connecting the Transmit of the RBPi to the Receive pin of the BUB, and the Transmit of the BUB to the Receive of the RBPi. Unless you follow this method of connections, BUB and RBPi will be unable to communicate with each other. For connecting with the RBPi, another very important thing to take care on the BUB is the logic level jumper. Make sure and double-check that it is connected to the 3.3V rail and NOT to the 5V.

Now that you have everything under control, boot up your RBPi, plug in the BUB and connect the other end of the serial cable to the USB port on your computer. All FTDI chips have a unique ID and this will show up as the device name. The device will be available under the /dev directory if you are using a Mac or Linux computer. On Linux, the BUB will show up as /dev/ttyUSBx, where x will depend on the number of USB devices already plugged in.

Use F-RAM to Replace SD Card in Raspberry Pi

For those who use their Raspberry Pi very frequently, there is always the risk of wearing out the SD card. This tiny, inexpensive, credit card sized, single board computer – the Raspberry Pi – or RBPi, boots and runs a Linux Operating System held on an SD card. Therefore, if your RBPi has to boot often, you run a database on the SBC or use virtual swap space that resides on your SD card, the life of the SD card reduces very fast.

In fact, any time you use the SD card, for example, for data logging, serial or network capture or while reading sensors, you are saving data to the SD card at fairly frequent intervals. Similarly, when you run a customized server on an RBPi such as an email or a web server, the system writes temporary or configuration files constantly to the SD card. That puts the SD card at risk.

The problem with SD cards or any other standard Flash-based memories and EEPROMs is that they require a block erase before writing any data. These devices have a limit to how many times these erase cycles may be used.

However, you can supplement the Flash-based SD card of your RBPi with an F-RAM board, called the Ironman. The first advantage is that F-RAM does not require any erase cycle to write new data, which makes it very fast. Secondly, F-RAMs can be written limitless times, so it will last a very long time. Thirdly, F-RAMs do not need external batteries to retain data. This video compares the three types of memories.

All over the world, nearly two million RBPis are running from SD cards. The RBPis write data frequently to the Linux root partition stored on their individual SD cards. On average, after 10,000 writes, an RBPi may fail to boot, losing all the data and configuration. Using an F-RAM card that adds 1-4 MB memory allows your SD card to be used as read-only. All the small databases, log-files, temporary files, configuration files, caches and anything that changes during normal use, goes on to the F-RAM card. That prevents use of precious kernel or application memory from the built-in RAM or tmpfs of the RBPi. The best part is that all the temporary files are available even after a reboot.

F-RAM or Ferroelectric RAM is very well suited for embedded systems. Being non-volatile, it does not require power or battery backup to retaining data up to 10 years. There is no restriction on erase/write cycles, making it as fast as SRAM. Unlike EEPROMs or Flash, there is no limit to the number of writes before device failure. The only disadvantages of F-RAM are cost and density/size.

F-RAMs can be read and written to up to 100 trillion times. To put that figure in understandable terms, you could write to the same address on the F-RAM chip 1,000 times per second continuously every second over 317 years – without the device failing. If the same process were to be tried on a Flash memory, the device would fail in just 100 seconds.