The modern Internet is a miracle of engineering and one of the largest machines ever built. Its presence can be found just about anywhere someone has a cellular or satellite phone. It provides information and connectivity to billions of people around the globe, but it doesn’t end there.
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A silent evolution is underway as a new breed of “things” connects to this massive network. In fact, more devices are connecting without any human interfaces. These connections are happening through new lower-power wireless networks, providing new services and capabilities and leading to the next major uptick in the Internet’s ever-increasing node count.
In 1958, following the year of Sputnik, Dwight D. Eisenhower formed the Advanced Research Projects Agency (ARPA, later changed to the Defense Advanced Research Projects Agency or DARPA). One of the first projects to come from this newly formed “think tank” was research in networking technology that could withstand a nuclear attack. This technology later became the fundamental architecture of the Internet. It was unimaginable then that a network could comprise billions of nodes and be accessible anywhere on the planet, yet today the Internet is ubiquitous.
Machines without human interfaces are joining the number of connected nodes, driven by a new low-power wireless revolution called machine-to-machine (M2M) communications, since these devices talk to other machines. For example, the Nest Thermostat has a simple user interface. But much of the time, it is reporting to a server via the Internet to collect information on how HVAC systems are used and provide a log of the activity. It also supports remote control capabilities.
M2M nodes routinely talk to other machines without human intervention. Typically they connect to the Internet via Wi-Fi (802.11) due to both the simplicity and the low cost of Wi-Fi components. Semiconductor manufacturers have been increasing the integration level of 802.11 nodes and devices, such as the Texas Instruments SimpleLink Wi-Fi CC3000module, which comprises the entire solution, including the software stack and antenna. This level of integration can enable a completely new generation of Internet connections, but it doesn’t stop here.
Wi-Fi is great for connections in the home where there is almost certainly a basestation connected to a cable or DSL modem. However, Wi-Fi uses a significant amount of energy and can require greater than 100 mW when communicating. It can quickly draw down a battery in an untethered device, limiting these applications.
Bluetooth wireless technology, however, uses far less power—on the order of 2 mW in operation and far less in standby. It is found in wireless headsets, speakers, keyboards, and mice where longer battery life is essential. Bluetooth is used primarily for ad-hoc or peer-to-peer connection modes. Two devices can be wirelessly connected and exchange data such as the application in a wireless keyboard.
Cellular phones have persistent connections to the Internet, so Bluetoothdevices that are “paired” with a phone can piggyback via an “app” and connect directly to the Internet. Devices then can either acquire or report information while in the presence of the phone with the application running. In sporting and fitness applications, users wear a sensor band using Bluetooth that connects to the phone via an application. The application “relays” information gathered from the sensors and stored on a server for users to review.
To even further extend battery life for applications that must be run off of non-rechargeable cells, Bluetooth low energy was introduced in 2011 as Bluetooth Smart. This technology differs from the “classic” Bluetooth in several areas all aimed at reducing power consumption to the point of running “always-on” for years. For example, combining TI’s CC2541 Bluetooth low energy system-on-chip with TI’s TPS62730 step-down converter can significantly prolong battery life. This combination reduces active mode current draw from a coin-cell battery by 20%.
With a 50-meter range and an application throughput of roughly 270 kbits/s, many new M2M applications are possible including wireless security systems, remote telemetry, monitoring, metering, and proximity detection, plus far more applications that can run for years on a coin cell. Like the Wi-Fi model, a simple Bluetooth low energy “gateway” product can connect these devices to the Internet.
Imagine buying a home security system that is nothing more than a Wi-Fi or cellular Bluetooth low energy gateway, a number of battery-powered wireless sensors that you place around your home (within 50 meters of the gateway unit), and an “app” for your smart phone. The sensors talk to the gateway, which in turn talks with servers that monitor the state of the system, whether you are home or away.
The user interface is the app on your phone. If a sensor detects a condition outside of the norm, an alert can be sent to a monitoring station, your cell phone, or both. Installation could take less than 30 minutes and only requires changing batteries once every three years. Bluetooth low energy-enabled sensors make it possible.
The Bluetooth low energy revolution is only one technology adding nodes to the Internet. ZigBee, 6LoWPAN, and other wireless technologies are all contributing more machine-only connections. Unlike Bluetooth, ZigBee’s architecture is a mesh network that allows one node to act as a repeater to another (see the figure).
Several paths are possible, so the loss of one node is not critical to the network’s continued operation. ZigBee’s physical layer depends on radios that are built to the 802.15.4-2006 standard. What is most interesting about ZigBee are the extensions to the protocols specific to machine-only end markets.
Protocols include ZigBee Smart Energy, ZigBee Home Automation, and ZigBee Light Link. They all take advantage of the mesh architecture and allow the network to self-heal. They also are designed to connect non-computer devices together and ultimately (via a ZigBee gateway) to the Internet.
Home automation has been around since home computers and X-10 power-line carrier technology. However, these new protocols provide far more to the end user. It’s not just about turning on a light or remotely controlling a thermostat. It’s now about saving energy and building more efficient homes.
With the rising cost of electricity, as well as government legislation to improve efficiency, ultimately we will see networks of devices that are aware of the home’s occupancy and climate and then decide what should be powered—or not.
Appliances often have a “standby” current consumption, sometimes called “vampire” power (see “Turn Off Your Vampire Power To Save Your Money And Electronics”). This constant low-power consumption contributes to the overall inefficiency of many homes.
If the security system knows no one is home, smart power strips and appliances could simply turn off their user interfaces and go down to an ultra-low-power mode. Once someone walks through the door (or opens the garage door), the house wakes up and adjusts the HVAC to a comfortable temperature. The appliances once again wake up and are made ready as lighting adjusts to the ambient conditions.
These networks aren’t as farfetched as they might seem. Slowly and surely, this technology will appear in homes and businesses. Since it is wireless, it can be easily added to almost any structure.
It will only be a matter of time before smart power strips and cords will enable people to retrofit older devices such as LCD TVs, stereo components, washers, dryers, dishwashers, ovens, and more to be monitored (for power consumption) and controlled simply by replacing the cord. New cords will connect wirelessly to the Internet and allow other machines to help remove waste in power consumption when they aren’t in use. In time, all of these new devices will add millions (if not billions) of additional nodes to the amazing machine we call the Internet.
· For more information about Nest Thermostats and how they work, visit www.nest.com.
· For more information about wireless connectivity, go to www.ti.com/wireless-ca.
· Download this datasheet: www.ti.com/tps62730-ca.
Richard Zarr is a technologist at Texas Instruments focused on high-speed signal and data path technology. He has more than 30 years of practical engineering experience and has published numerous papers and articles worldwide. He is a member of the IEEE and holds a BSEE from the University of South Florida as well as several patents in LED lighting and cryptography.