Accelerometer-based wireless remote control powered with harvested energy

We present a design that can be used with a wireless battery-less switch in order to provide extra information to characterize the activity that should be performed. The low power design allows a microcontroller, an accelerometer and a radio to be powered using harvested energy. The data is then processed to yield the relevant information for the process. This device can be used for instance as an intuitive input element for dimming a light. It allows complex and expensive mechanical constructions to be replaced by reliable and low cost silicon

Récolte d’énergie pour alimentation des réseaux personnels sans fil : plus d’autonomie, plus d’économies, plus d’écologie!

Pour certaines applications dans lesquelles les capteurs sont associés en réseaux personnels sans fil, il peut être très coûteux ou même impossible de procéder à un remplacement de batteries. Dans ces cas, l’utilisation d’une alimentation basée sur les technologies de récolte d’énergie peut être la solution idéale. Cet article expose quelques technologies de récolte d’énergie et traite des facteurs à considérer lors de leur mise en oeuvre. Des démonstrateurs développés à l’InES de la ZHAW sont également succinctement présentés

Battery-less sensor nodes for 802.15.4/ZigBee wireless networks

Battery-free wireless sensor nodes are very convenient in many applications. They eliminate the costs associated with installing batteries and reduce maintenance headaches. For these reasons, they are gaining in popularity. Such devices usually require the use of an energy source that harvest power from the surroundings. Because of the necessity of harvesting energy and the related costs, there are limitations to the kind of application and wireless protocol that can successfully be implemented, especially when energy is produced intermittently. The interest in 802.15.4-based wireless systems such as ZigBee has also led to its consideration for battery-less nodes. In this paper we briefly discuss some of the challenges faced when using 802.15.4/ZigBee in applications where little energy is available. We then show that some of the recently introduced microcontrollers featuring FRAM memory allow interesting gain in energy, making it even easier to overcome the difficulties

A battery-less switch for use in 802.15.4 / ZigBee applications

Wireless switches to control light systems are important parts of wireless networks in building automation. For success, it is important to avoid frequent battery replacement, or even better to eliminate them. Although this is possible in some proprietary systems today, at the expense of some features, it is still a challenge for networks such as ZigBee. The main difficulties lie in the power available and the requirements for communication. In this paper, we present the design of a battery-less wireless switch that can be integrated in 802.15.4 / ZigBee systems. We use a standard energy harvesting module for generating power when the switch is activated. The important and required power management aspects implemented in hardware and software are discussed, in the light of the network specifications. After showing the challenges needed to overcome the use of a battery-less switch in wireless systems such as 802.15.4, we present our solutions and the results of some tests

Comparing the energy requirements of current Bluetooth Smart solutions

Bluetooth is becoming a popular way to get access to data delivered by sensors. To be convenient in use and low cost in maintenance, those sensors should consume as less energy as possible. Near the energy consideration of the sensing element, the proper selection of the Bluetooth Low Energy radio and software stack is vital to achieve low power consumption.  There are several solutions on the market, with various claims with regard to power consumption. These claims are not easy to verify on the basis of the data sheets alone, making it long and difficult for engineers to choose the appropriate solutions. We have measured the energy consumption of several Bluetooth Smart solutions that can be found on the market today. The measurements were based on the important communication phases and the information available in various documents (datasheets, application notes). The result of that work is presented here. The work was done at the end of 2013 and early in 2014

Advertising position with battery-less Bluetooth low energy

One application of the modern mobile phone is navigation. For instance, a GPS module placed in the mobile phone can be used to inform the user about his position. Coupled with the appropriate maps and information about where to go, the system can be used to lead the user to the right place. There are several places where the GPS signal is not available (or say not strong enough), and the position information is missing. In this work, we present a low cost tag that can be used to broadcast GPS coordinates (and other valuable information) using the new Bluetooth Low Energy wireless standard, particularly in places where the GPS signal is too weak. The low cost wireless embedded system is built using very low power communication concepts. Contrary to other similar devices, it can run on harvested energy, eliminating the need of a battery and therefore strongly reducing maintenance needs. The tag makes use of Ble ADV frames, resulting in a very simple system with low memory requirements. The pre-programmed coordinates of a given location can be sent on 1 or on all the 3 advertising channels of Ble using energy harvested from the environment light with a small solar cell. All this results in a very low cost active Ble tag, powered with energy harvesting

Affordable energy autonomous wireless sensor for day and night

Bluetooth Smart is enabling a new class of sensors where device configuration and data presentation can be done using smart phones, tablets, personal computers and even smart watches. Sensors are equipped with a wireless link that allows them to transfer data to other devices or to get information from them. This opens up many applications with high volume potential. The promise of a large market has led to an abundance of Bluetooth Smart solutions, which is a good thing for the consumer. Competition will lead to improved quality and will drive costs down. But there is also the danger of a maintenance nightmare, if questions such as energy consumption and security are not properly addressed. Sensors need a power source and the way this is often done is to use batteries. They are small and low cost. But maintenance of sensors powered by small batteries means finding them (if one can still remember where they are) and changing the batteries. This is both resource consuming and ecologically expensive. Energy harvesting can help bring the needed autonomy, reduce and even eliminate the maintenance issues as far as energy is concerned. So far however, energy harvesting has proved expensive. In this work, we use a new power management system to design a sensor that runs day and night on energy harvested using a very small solar cell.  Part of the energy harvested when there is enough light is stored for use at night. On-the-fly change of the measurement rate allows an optimal management of the energy. We succeeded in designing and building a system with a cost effective solar cell, which can run day and night on harvested energy

Harvesting energy from trees in order to power LPWAN IoT nodes

Low Power Wide Area Network (aka LPWAN or LPWA or LPN) nodes are important components in the IoT chain. They allow energy-efficient wireless communications between elements that can be several kilometers apart. This in turn should enable energy savings and facilitate the deployment of energy autonomous devices. However, energy autonomy is still in its infancy, as far as LPWAN is concerned. Most nodes run on mains or batteries. Mains seriously limit the mobility of the nodes and are only used in special cases. Batteries often lead to maintenance costs issues. Scavenging energy from the surroundings to achieve energy autonomy is an alternative that has hardly been used for LPWAN systems. In cases where energy harvesting has been used, solar energy has been the most popular source. Other methods are possible and could even be important alternatives. In this work we harvest energy from trees using TEGs. That energy is stored and used to power a long-range wireless embedded system (LoRaWAN in this case). Tests made for several months have shown that this method works well. Enough energy is harvested in all seasons, allowing sensing and transmission of data several times per day

Streaming speech and music using bluetooth low energy

The new Bluetooth Low Energy standard has mostly been promoted and used for applications where a low data rate is needed. For cases that require more bandwidth, Bluetooth Classic is still the preferred and marketed solution. A typical example is the streaming of music. In view of the popularity of Ble and its physical layer data rate, it is legitimate to investigate its practical throughput limits. To this purpose, we looked at different ways of using Ble transceivers to transmit data as fast as possible. We built a demonstrator that allows us to emulate several frame variations in order to improve the data rate for more demanding systems. The unconventional use of MIC positions for data allows us to be more efficient in transferring data. In this paper we summarize the first results of an on-going work

Indoor battery-less temperature and humidity sensor for Bluetooth Low Energy

In June 2010, the Bluetooth SIG adopted the first version of Bluetooth that includes the low energy specifications (4.0). Ble has been designed to allow devices running on a small energy budget to communicate with host stations such as mobile phones or personal computers. Bluetooth low energy is primarily meant to be used in applications that require small batteries. In this work we investigated the suitability of that new wireless protocol for a battery-free application. We chose a simple and yet useful application scenario, where temperature and humidity are measured in an office environment and the results are wirelessly sent to a host. The use of the new sensor SHT21 from Sensirion allows temperature and humidity to be precisely measured with a small energy budget. For sensors to be moved and placed conveniently, a wireless system based on the EM9301 Ble radio of EM Microelectronic is implemented. The EM6819 is used as microcontroller to control the system. Energy autonomy is provided by a flexible and small solar cell from G24i. Temperature and humidity data can be displayed or transferred to the right place by using the appropriate PC or mobile phone fitted with the wireless link. As far as we know, this is the first work of this type using a battery-less sensor and Ble for communication