Author Archives: Andi

A Camera to See around Corners

That light travels in straight lines, is a well-known fact of physics. This property of light prevents us from seen around corners, unless helped by a mirror. However, scientists have not allowed this limitation to prevent them from developing a far from average camera that can see around the average corner, without using x-rays or mirrors.

Genevieve Gariepy, along with his group of scientists, has developed a latest device with a detector that treats walls and floors as if they were virtual mirrors. Along with some clever data processing techniques, this amazing device has the power and is able to track moving objects that are out of its direct line of sight.

A mirror works by reflecting scattered light from an object. As the surface of a mirror is usually shiny, all the reflected light travels in a well-defined angle. As light scattered from different points on the object travel at the same angle even after reflection, the eye sees a clear image of the object. On the other hand, light reflected from a non-reflective surface is scattered randomly – preventing us from seeing a clear image.

At the University of Edinburgh and the Heriot-Watt University, researchers have found a way to tease out information on an object even when light from it is scattered randomly by a non-reflecting surface. They have published their method in Nature Photonics and it relies on the technology of laser range finding. This technology measures the distance of an object by the time it takes a light pulse to travel to the object, scatter and return to the detector.

In principle, the method of measurement is similar to range finding by ultrasonic technology. Only, instead of sound pulses, researchers use pulses of light. In practice, researchers bounce a laser pulse off the floor making it scatter. A tiny fraction of the laser light striking the object backscatters on the floor. The detector records the back scattered light from the virtual mirror spot, close to the initial spot where the laser strikes.

The speed of light is a constant and a known factor. Therefore, the device triangulates the position of the object by measuring the time interval from the start of the laser pulse to the scattered light reaching the patch on the floor. There are a few difficulties involved with this method.

The light levels the detector has to detect on the virtual spot are extremely low. Moreover, the timing measurement has to be accurate to within 500 nanoseconds or 500 billionths of a second. To overcome both these obstacles, researchers had to go in for some serious laser and detector technology. They had to use a laser pulse only ten femtoseconds long for the timing measurements.

The ultra-sensitive camera uses a one-pixel avalanche diode array called as SPAD to detect the image on the patch of the floor. The combination acts as an ultrafast stopwatch for recording the time the light pulse arrived after scattering. All this happens within a few billionths of a second.

It helps if the out of sight object the device is trying to locate is moving, while the nearby objects are not. The moving object then generates an image that changes with time and this can be filtered from the unvarying background.

How Sensors help Seniors Live Independently

With the benefits of medical science and increased awareness, people are now living longer than their ancestors did. Along with longer living, they also desire to live as independently as possible in their senior years. However, certain risks are part of independent lifestyles. These include inadequate care resulting in deteriorating health and debilitating falls. Researchers are addressing these issues by developing smart homes. They are using sensors and other devices and technologies for enhancing the safety of residents while monitoring their health conditions.

In-home sensors permit unobtrusive monitoring of individuals. That offers enormous potential for providing timely interventions and for improving the health trajectory, because health problems can be detected early, before they become more serious. Therefore, individuals are assured of continued high functional ability, independence with better health outcomes.

University of Missouri has an ongoing project in HAS or Health Alert Systems using sensor technology. They are testing HAS in senior housing in Cedar Falls, Iowa and in Columbia, Mo. They presently use motion sensors to monitor activity, acoustic and vision sensors for fall detection, Kinetic depth images for gait analysis and webcams for silhouette images. They have a new hydraulic bed sensor to capture quantitative restlessness, respiration and pulse. HAS also uses pattern recognition algorithms for detecting pattern changes in the data collected by sensors. Based on this, HAS can generate health alerts and forward them to clinicians, who diagnose them further to determine appropriate intervention.

Researchers at the university are evaluating the usability and effectiveness of HAS for managing chronic heath conditions. They are presently testing the HAS at remote sites, away from healthcare providers. Researchers expect this approach will provide important information on ways to scale up the system into other settings. According to the researchers, the next big step will be to move the system into independent housing where most seniors prefer to be. This will also offer significant potential healthcare cost savings, enabling seniors to live independently.

This research will improve the health care and the quality of life for older adults. Researchers are focusing on newer approaches for assisting health care providers in identifying potential health problems early. This will offer a model in eldercare technology, which will keep seniors independent while at the same time, reducing healthcare expenses. The project also has a plan – It will train the next generation of researchers in handling real, cyber-physical systems. It will mentor students through an interdisciplinary team, while the research outcomes are integrated into the classroom teachings.

Similar efforts are also under research in other places. For example, researchers at the Intel Labs, Carnegie Mellon University in Pittsburgh, are working on ways of taking out the drudgery involved in housework. They are presently designing HERB or Home Exploring Robotic Butler, a smart and resourceful robot. According to the researchers, HERB will be able to walk into a room, assess its layout and move about by itself.

Researchers at Intel Labs believe disabled and senior citizens will adopt robot butlers early on, as they most need help around the house.

How Smart Sensor Technology helps Beehives

Plants are necessary for life on the planet Earth, as they transform the gas Carbon-Di-Oxide that animals exhale into life-sustaining Oxygen. Plants, in turn, depend largely on bees to pollinate their flowers and propagate thereby. That makes honey bees a keystone species, which humans have recognized throughout history. Bees help to pollinate nearly 70% of all plants on earth assuring about 30% of the global food supply. That makes bees a predictor of our planet’s future health.

Global warning has brought with it an alarming rise in the growth rates of damaging pathogens such as fungi, viruses and mites. At the same time, there has been a serious disrupt in the natural rhythms that the bee population had adapted over centuries of consistent seasonal weather patterns. Crop production is infested with pesticides, which bees ingest and transmit back to their hives during pollination. This often leads to a total collapse of colonies. Electromagnetic radiation level in the atmosphere is rising with the exponential growth of cell phones and wireless communication towers. This interferes with the ability of the bees to navigate in flight.

All the above has made it imperative for scientists to monitor the activity of honey bees within their hives in the daytime as well as at night including during inclement weather. At the University College of Cork in Ireland, a group of food business, embedded systems engineering and biology students have recently taken up the challenge. They have developed a unique platform for monitoring, collecting and analyzing activity of bees within the colonies unobtrusively.

The project Smart Beehive has earned top honors in the Smarter Planet Challenge 2014 of IEEE/IBM. Using mobile technology, the project deploys big data, wireless sensor networks and cloud computing for recording and uploading encrypted data.

Waspmote is a modular hardware sensor platform. Libelium has developed Waspmote for any sensor network and wireless technology to connect to any cloud platform. The UCC team of students has used Waspmote as their starting point along with integrated hive condition and gas sensors. They have used ZigBee radios, GSM and 3G communications to study the impact of oxygen, carbon dioxide, humidity, temperature, airborne dust levels and chemical pollutants on the honey bees. The students captured data from initial observations in two scientific papers and three invention disclosures.

According to the famous physicist Albert Einstein, man can survive only for four years on earth if there were no bees left. Smart technology can integrate beehive sensors and analyze the data they collect. Therefore, such platforms play a critical role not only in ensuring continuation of pollination, but also in ultimately monitoring, understanding and managing the precious global resources as well.

The Plug & Sense! Technology from the Libelium Waspmote wireless sensor platform offers the use of a wide range of sensors, integrating more than 70 of them at a time. It can adapt to any scenario of monitoring with wireless sensors such as water quality, vineyard monitoring, livestock tracking, irrigation control, air and noise pollution, etc.

Outdoor deployment is possible because of the waterproof enclosures used by Plug & Sense! Moreover, using solar panels, the honeybee project has the ability to harvest energy.

The Popp-Hub Home Automation Gateway with the Raspberry Pi

Sometimes it is necessary to monitor the home remotely, such as when you are away on a vacation. For this, you need to hook up all the sensors in the home to the Internet for remote monitoring and control. To avoid the complexity of wiring, people prefer wireless devices for monitoring the sensors. As wireless devices could also be in the form of nodes, with each node monitoring multiple sensors, you need a gateway acting as a bridge for connecting many wireless nodes to the Internet.

Launched by Z-Wave Europe and Popp & Co., Popp Hub is one such home automation gateway. What distinguishes it from others available on the market is it is based on the famous Single Board Computer, the Raspberry Pi or RBPi running Linux. The Z-Wave Plus home automation Popp Hub supports Z-Wave and IP smart devices.

The reference design of the Popp Hub gateway includes a software stack certified by the ZigBee Home Automation. It also includes tens of APIs for simplifying the ZigBee integration and the development of applications within a Linux system. The APIs incorporate TCP/IP for the ZigBee bridge as this enables easier integration of low power connectivity solutions and faster development of applications. The included USB dongle is CC2531-based and it runs the ZigBee HA1.2 certified Protocol Stack, MAC and PHY – this has been extensively tested for interoperability.

Z-Wave Europe GmbH is Europe’s largest distributor for all devices based on the Z-Wave wireless technology. They sell and distribute the Popp Hub smart IP home gateway on behalf of the UK-based Popp & Co. The Single Board Computer RBPi2 in the Popp Hub runs the Z-Way Middleware. According to Z-Wave Europe, Z-Way Middleware happens to be the first Z-Wave controller certified to the new standard, the Z-Wave Plus.

Z-Wave Europe claims you can connect Z-Wave wireless enabled devices sourced from more than 300 device manufacturers to the 89x71x25mm Popp Hub. These devices could be remote controlled devices, for windows and blinds, alarms, lighting, security or HVAC. Additionally, Popp Hub is capable of working with several non Z-Wave devices as well, such as IP based devices, plugins and IP cameras.

Users can use a mobile Android or iOS application, a remote control or a single wall switch to control up to 230 Z-Wave devices connected to the Popp Hub. This includes features such as selectively activating the heating system or closing windows automatically depending on changes in the weather conditions. If a sensor device has set off any alarms, you will receive a notification from the application.

The RBPi2 is a 900MHz, quad-core Cortex-A7 SoC that runs on 1GB of RAM and Linux-based firmware. All major ports of the RBPi are exposed to the user. Besides, it has an audio jack, an Ethernet port and four USB ports. You can use Wi-Fi or other wireless devices on the USB ports. The internal SD slot handles the 8GB SD card that holds the Operating System.

Within the Popp Hub, a Sigma Designs SM5202 chip augments the basic RBPi2 functionality. This is a static controller certified by Z-Wave Plus and it provides 48 command classes and adds enhanced security.

Thin Clients with the Raspberry Pi

When deploying a large number of computers at a single location, it is a common practice to employ thin clients. In such cases, several client computers access a powerful central server computer that controls resources such as the hard disk data and Internet access. The logical operating system of the server is isolated from the clients accessing it via a concept known as desktop virtualization.

Implementation of desktop virtualization or VDI follows several conceptual models. One can broadly divide them into two categories depending on whether the operating system executes locally on the client machines or remotely on the server. Therefore, desktop virtualization may not always involve the use of virtual machines.

When the desktop virtualization uses a host-based form, users have to view and interact with their desktops over a network. For this, they must use a remote display protocol. As all processing takes place at the data center housing the server, client devices can be tablets, smartphones, zero clients and thin clients.

Citrix offers a suite of products known as Citrix Receiver with which client devices can easily connect to different desktop virtualization services from Citrix. They offer several types of client platforms and form factors. Included in these are embedded operating systems. zero clients, thin clients, Google Chromebook, Linux, Blackberry Playbook, Blackberry, Android, iPhone, iPad, Mac OS X, Windows Mobile and Windows.

For example, using Citrix Receiver technology, users can connect their client devices to XenDesktop and XenApp desktops and applications via the HDX protocol. They can also connect to the Citrix Access Gateway, XenVault secure storage and other Citrix services.

Citrix has since decided that putting a lot of effort into creating special versions of Receiver for one device is inefficient. Therefore, it has decided to work with the Pi Organization for ensuring their Linux Receiver would work with the new architecture of Raspberry Pi Model 2 or RBPi2 and its supported OS images.

With this effort, it is no longer necessary to have hardware-accelerated plugins for the RBPi2. The new HDX Thinwire and XenDesktop/XenApp 7.6 FP3 compatibility codecs work efficiently on the RBPi2. On the other hand, ThinLinx makes a Thin Client & Digital Signage Operating System for the RBPi. Citrix has tested this OS and has confirmed it is capable of handling video with impressive speed.

According to Citrix, their selection of RBPi2 as a thin client for VDI is based on the inherent security feature of the Single Board Computer. The SBC is secure as there is no on-board storage and the SD card of the computer can be removed and stored in a safe place when not in use. An additional factor is the price. RBPi is far cheaper than any other thin client available in the market. Another advantage is in addition to vanilla models, you can also have custom RBPis as thin clients.

That the RBPi is an interesting VDI option also comes from the fact that all dedicated thin clients require the same hidden costs to make them useful. This includes pointing devices, keyboards, Wi-Fi dongles, SD cards, USB hubs and monitoring devices.

Computer Translated Sign Language

There are many people in the world who cannot hear because their hearing ability is impaired. This disability also precludes them from holding audible conversations with others. For a long time, telephone calls dominated the long-distance communication scenario. However, over the past couple of decades, other means of communication have also evolved, such as emails and text-based messaging. Although these supplement voice calls largely, the problem of face-to-face communication with the deaf still remains.

Using sign language is one means of face-to-face communication that the hearing-impaired use and this is as efficient as their methods of communication using smartphones, tablets and computers. Similar to using any other language, two people can communicate face-to-face only when both are capable of using the sign language. Lately, communication between two individuals is now easier because of the use of translators in computers. This allows the user to understand even when they do not understand the spoken language.

Now MotionSavvy is using the same technology for translating sign language to another language that the user can understand. They are using a dedicated tablet, Uni, created to enable efficient two-way communication between those who can hear and those whose hearing is impaired.

Uni involves the use of two distinct technologies. First, it monitors sign language by using integrated cameras and interprets the signs using a special recognition software. Then it translates the signs into spoken words. The other part of the technology involves converting spoken words into text. This happens when the other person responds by speaking. Uni converts this speech into text, displaying it on the screen for the deaf person to read.

The World Federation of the Deaf claims there are more than 70 million deaf people in the world. With the technology offered by MotionSavvy, there is a dramatic potential to influence the lives of such people.

MotionSavvy is launching Uni with the ability to read at least 2000 signs initially. They will be issuing updates for adding more signs. However, they are offering SignBuilder software, with which users can configure new signs.

Uni is available in two versions – hardware and software. You can buy the hardware device that includes the software, or the software alone. You can use the software-only solution on a computer that has the Leap Motion controller. For both solutions, users need to pay a monthly subscription that allows them access to SignBuilder and CrowdSign.

The basic Uni Dictionary contains about 2000 signs. Although this confers the ability to hold meaningful conversations, individuals can add new vocabulary to Uni Dictionary with the help of SignBuilder. They can also share the new signs with others on the Uni network, by using the software CrowdSign. MotionSavvy expects the number of signs to grow exponentially with people using the two software programs.

At present, Uni is able to recognize signing by hands in front of its camera. Eventually, MotionSavvy expects to implement recognition of all facial emotions. Uni is working for people using signs such as CASE or SEE. MotionSavvy is working on improving recognition and adding more features to accommodate culturally strong ASL users as well.

A USB Hub with a Raspberry Pi Zero

Computers available today come with only one or two USB sockets. With the multitude of USB or Universal Serial Bus devices we use today, it is easy to run out of sockets. For example, you may have to connect your mouse, keyboard, printer, webcam and microphone, all operating on USB technology, to your computer. With only two ports available, it is obviously a difficult task.

However, there is an easy solution. You can use an inexpensive hub. According to the USB standard, which also covers USB hubs, they can support up to 127 devices. Typically, a USB hub has four ports, but some models can have more. Operation of a hub is plug-n-play. You plug the hub into your computer and plug your devices, including other hubs, into its ports. Chaining hubs allows you to build up dozens of available USB ports on your computer.

USB devices can use their own power supply or they can draw power from the computer they are connected. Devices that draw power from the host computer are mostly low power devices such as mice and digital cameras. According to the USB standards, a USB 2.0 port can power devices drawing a maximum of 500 mA and a USB 3.0 port allows devices to draw up to 900 mA maximum.

Self-powered devices connecting via the USB port do not need to draw power from the host computer. For example, your computer does not need to supply power to printers and scanners connected to it. For connecting many unpowered devices to your computer, you will need a hub that has its own power supply, so that the devices do not load the computer’s supply. Such hubs have their own power supply that supplies power to the bus.

If you have the single board computer, the Raspberry Pi or RBPi, especially the Zero version, it is easy to convert it into a USB hub. Frederick had a LogiLink UA0160 USB hub lying around and he used it together with an RBPi Zero to make a powered hub with four ports. He removed the board from its casing and connected the power points to the power points of the RBPi Zero. Since the form factor of the hub board matches that of the RBPi Zero, the entire assembly looks neatly done.

For supplying power to the hub, you will need to connect PP1 of the RBPi Zero to the 5V point of the hub and PP6 of the RBPi Zero to the GND of the hub. Next, you have to connect the USB OTG from the RBPi Zero to the USB port of the hub. For this, use two wires to connect PP22 of the RBPi Zero to the D+ on the hub and PP23 of the RBPi Zero to the D- of the hub.

Use an ohmmeter to check for any shorts between the hub and the RBPi Zero. Additionally, make sure all connections are correct. Use some insulating material such as a plastic board between the hub board and the RBPi Zero, before bundling everything together. If possible, get a case to house the combination and you are done.

Mica Capacitors : Why should I use them?

Mica, a phyllosilicate, is a group of hydrous potassium/aluminum silicate material. It is a rock-forming mineral exhibiting a two-dimensional sheet or layer structure. That means it is possible to split mica into thin sheets. The biggest advantage of mica is the excellent stability of its electrical, chemical and mechanical properties. This property makes mica a suitable material for use as a dielectric when making highly stable and reliable capacitors. Silver-mica capacitors are useful at high frequencies, because of their low resistive and inductive losses and high stability over time.

Delved in India, Central Africa and South America, the most commonly used are the muscovite and phlogopite mica. While the first has superior electrical properties, the latter has a higher temperature resistance. Mica capacitors are expensive as the raw material composition has high variation, requiring inspection and sorting. Silver mica capacitors have sandwiched mica sheets coated or plated with silver on both sides. The assembly is then encased in epoxy to protect it from the environment.

Tolerance and Precision

Among all types of capacitors, silver mica capacitors offer the lowest tolerances, as low as +/-1%. In comparison, ceramic capacitors have tolerances going up to +/-20% and electrolytic capacitors can have more.

The design of a silver mica capacitor does not allow any air gaps inside. Additionally, the entire assembly is sealed hermetically from the environment. That allows the mica capacitor to retain its value over long periods. As the assembly is protected from the outside effects of air and humidity, the capacitance of a mica capacitor remains stable over a wide range of temperature, voltage and frequencies. The average temperature coefficient of mica capacitors is around 50 ppm/°C.

Losses

Mica capacitors have a high Q-factor. This comes from the low resistive and inductive losses exhibited by these capacitors. That makes them a suitable choice for use at high frequencies, but it comes at a price – silver mica capacitors are expensive.

It is difficult for manufacturers to make silver mica capacitors of larger capacitance value. Typically, this ranges from a few pF up to a few nF. However, they can stand high voltages and mica capacitors are usually rated for voltages between 100 and 1000 volts. Special mica capacitors are rated up to 10KV and these are mostly for use with RF transmitters.

Applications

You can use silver mica capacitors wherever the application requires low capacitances, high stability and low losses – especially in power RF circuits – requiring very high stability.

You can also use silver mica capacitors in high frequency tuned circuits such as oscillators and filters. Pulsed applications such as snubbers also use mica capacitors as they can withstand high voltages. If cost is an important factor along with tolerance and low losses, you can replace mica capacitors with class I ceramic capacitors. Ceramic capacitors are available at a fraction of the price of mica capacitors.

Mica capacitors are available as surface mount versions as well. This offers several benefits over radial or axial assemblies. By eliminating the leads, SMT designs offer a smaller device size that can be mounted directly to the PCB – resulting in a more compact design and greater mechanical stability.

Waspmote Plug & Sense! : Solar-Powered Wireless Sensor Platforms

Today, we use sensors for a myriad of activities such as intrusion detection, fall detection, patient surveillance, art and goods preservation, offspring care, animal tracking, selective irrigation, and many more. Where the sensor network has to operate outdoors, what can be a better way of powering them other than through solar means?

Using an external or internal solar panel, one can safely recharge batteries for the system. For external solar panels, the panel is usually mounted on a holder tilted at a suitable angle ensuring the maximum performance of the outdoor installation. When space is a major challenge, such as indoors, the solar panel can be embedded on the front of the enclosure. Typical rechargeable batteries used for powering loads are rated 6600mAh, and this ensures the sensors do not stop working even when the sun is not providing adequate light.

Such platforms of wireless sensor networks provide solutions for Smart Cities. Waspmote Plug & Sense! from Libelium is a system of encapsulated wireless sensor devices that allow system integrators to implement modular wireless sensor networks in a scalable manner. The Libelium system reduces the installation from days to just hours.

Each node of a Waspmote Plug & Sense! comes with six connectors. You can connect sensor probes to these connectors directly and the system is ready to install and easy to deploy. Using connectors ensures that the services remain scalable and sustainable. The possibility of powering the platform through solar power allows energy harvesting and years of autonomy.

Once the sensors have been installed, the nodes on the Waspmote Plug & Sense! can be programmed wirelessly. This is possible because of the special feature, OTAP or Over The Air Programming, incorporated into the platform. Thanks to OTAP, users can replace or add sensors without having to uninstall any of the nodes. This helps to keep the maintenance levels within reasonable limits. For example, to extend the service, you can easily add a noise sensor to a network consisting of CO2 probes, simply by attaching it.

The applications are endless for the Waspmote Plug & Sense! platforms. Apart from Smart Cities, the models are preconfigured for creating other widely applicable services out of the box, such as radiation control, ambient control, smart security, air quality, smart agriculture, smart parking and so many more.

You can use these sensor platforms anywhere in the world, as they use the generally available radio frequencies 2.4GHz and 868/900MHz, besides complying with certification standards such as CE, FCC, and IC. Usually, these sensor platforms send information to a sensor gateway that in turn, uploads the data to a cloud service. Therefore, the data is accessible from anywhere in the world and users can integrate it easily into third-party applications.

Use of solar-powered wireless sensor networks makes it so easy for adding a new sensor that municipalities find they do not have to reinstall the network for Smart Cities. The solution reduces the complexity of the installation and its maintenance, while providing it with a high degree of scalability. Available with IP65 enclosures for outdoor deployment and no software license fees, these platforms offer remarkable opportunities.

Connecting To a Raspberry Pi via an Ethernet Cable

You can use your Raspberry Pi or RBPi single board computer in different ways. Sometimes you may have a keyboard, mouse, and display to connect to your RBPi to use it as a regular computer. At other times, you may prefer to communicate with it through another computer such as a desktop or a laptop. Your method of communication may also vary. For example, if your RBPi is at a distance, you may have to connect to it over the Internet via Wi-Fi.

However, Wi-Fi may be an unreliable and a slow way of connecting to your RBPi if you are communicating with it often using SSH or a remote desktop application. Rather, a faster method would be to use a direct Ethernet connection, which would also be a lot more stable. Since you are connecting to your RBPi directly with an Ethernet cable, you are actually bypassing your local network and not sharing the bandwidth with other computers. Moreover, a direct Ethernet connection allows you to connect to your RBPi even when you are away from your home network, experiencing slow connectivity and or network time outs.

For this, all you need is an Ethernet cable. You will need to assign a static IP address to the Ethernet port of the RBPi. The static IP address will depend on the IP address of the computer and its Ethernet adapter that you will be using to connect to the RBPi. The process of assigning a static IP address is straightforward and should be easy for any OS.

If you are using a Windows computer to connect to your RBPi, open up the Network Connections window from the task bar or by accessing the Control Panel. Now look at the Properties of the Ethernet connection under Internet Protocol Version 4. This will show an IP address of the form 10.0.0.6 or similar.

In some cases, the internet connection may also be set for automatic assignment. Here, you need to connect your RBPi to the computer via an Ethernet cable first. Now access the Windows command prompt and use the ipconfig command to see the address your computer has automatically assigned to the connected RBPi. Next, you will also need to note the default gateway IP, which is the local IP address of your network router.

Apart from the above, you will also need to find out the IP addresses of the domain name servers used by your RBPi for finding websites on the Internet. This you can find out by executing the command cat /etc/resolv.conf on the command prompt of your RBPi.

Now you must edit the /etc/dhcpcd.conf file on your RBPi and modify the three IP addresses in the file. Change the last number of the IP address of your computer’s Ethernet adapter, to any other number between 0 and 255. This becomes the static IP address you will use to SSH or connect remotely to your RBPi.

The static router is the IP address of the default gateway IP you noted earlier and the static domain name servers are the IPs you noted from the /etc/resolv.conf. Save the dhcpcd.conf file and reboot your RBPi. Enjoy your connection.