Anticipating the new home wireless network (ZigBee RF4CE) that will arrive in stores later this year, Cees updates us on three new ZigBee profiles for consumer electronics.
Are you ready to say hello to the next generation of remote controls? ZigBee RF4CE-powered remotes are hitting the market this year. So are the RF-connected set-top boxes and TV sets that will enable end users to leverage the power of RF.
The arrival of next-generation remote controls means an end to the handicap of infrared (IR). No more having to point an IR-connected remote at a TV or other electronic gadgets. By using RF, end users can access and manage their entertainment systems from almost anywhere in the home. In addition, the new interactive RF-powered remotes have a slew of new features, including the innovative “Find Me” button. Is your remote control lost, hiding in a child’s room, or underneath the sofa? Just press the “Find Me” button on the TV or set-top box, and the remote will start buzzing and blinking, making it easy to find.
Remote Control 2.0 is also green. By using the new ZigBee RF4CE technology with its ultra-low-power wireless networking capability, it is now possible for consumer electronics manufacturers to design remotes that never have to have their batteries replaced or recharged. Currently, a remote control’s battery may last two years at most with minimal use. In comparison, with a ZigBee RF4CE remote, a single coin cell type battery can last 10 years or more. At a minimum, that is a fivefold decrease in the number of batteries needed. As batteries are composed of heavy metals and toxic materials, this means a fivefold decrease in the amount of the toxic materials that need to be mined, refined, and then disposed of. As fewer batteries need to be made, this greatly reduces the CO2 footprint for the energy used in the mining, refinement, and manufacturing process.
Similar to Wi-Fi and Bluetooth, ZigBee operates in the 2.4 GHz band. Based on the IEEE 802.15.4 wireless standard, ZigBee is a Local Area Network (LAN) radio technology developed for low-power and low-data-rate applications. ZigBee Green Power, ZigBee SE 2.0, and ZigBee RF4CE are the three flavors (Figure 1).
ZigBee PRO and SE 2.0 are targeted for (Smart Energy related) industrial, commercial, telecommunication, and residential uses – especially for those applications where power is not a critical factor. Such applications include home power management and monitoring and the so-called “Internet of Things.” Within the Internet of Things each of the home appliances has its own IP address and can be addressed via the Web. (Hence the need for IPv6 with its nearly unlimited supply of IP addresses.)
On the other end of the spectrum is ZigBee GreenPower, targeting devices with limited data rate and minimal power requirements. This includes devices such as light switches that are powered solely by the movement of the switch itself, as well as home energy harvesting and energy scavenging sensor applications, which could be powered by sunlight, vibration, sound, and other sources.
For home entertainment, the most exciting ZigBee flavor is ZigBee RF4CE. Originally developed by four of the major consumer electronics companies – Panasonic, Philips, Samsung, and Sony – under the name of RF4CE, which stands for Radio Frequency for Consumer Electronics, RF4CE was adopted by the ZigBee Alliance and has now become known as ZigBee RF4CE.
The ZigBee Alliance developed RF4CE to link together the entire household. Entertainment systems – as well as the home’s sensors, monitors, and controls – all connect to each other and to the outside world via the set-top box and the cloud. Among the major players pushing the adoption of ZigBee RF4CE are the service providers who believe this new networking technology will enable them to expand the set-top box’s household penetrations to include a wide range of new services and applications in addition to entertainment and Internet access.
The three ZigBee RF4CE profiles
Three ZigBee RF4CE profiles target different in-home and networking applications.
- ZigBee Input Devices (ZID) for pointing devices, replacing Bluetooth and IR for Internet-based TV
- ZigBee 3D Sync (Z3S) for 3D glasses and TV sets
- ZigBee Remote Control (ZRC) for a wide range of home sensors, entertainment systems, TVs, and the like – all connected to a remote control and/or a set-top box
ZID was developed for Internet TV as well as for touch pads, mice, keyboards, wands, and similar devices for use with a variety of laptops, computers, TV sets, set-top boxes, and other electronic devices. Unlike IR devices, the ZID profile allows consumers to use their devices from greater distances or even from another room because operation is not limited to line of sight. The ZID energy-efficient design helps devices run longer on batteries when compared to IR technology and will greatly reduce the total number of batteries used – and disposed of – during the device’s lifetime.
The standard offers native support of popular multi-touch and gesture commands, allowing manufacturers to deliver the most feature-rich products for their customers. It also features the ability to define special functions and enhanced performance beyond the standard behavior of a mouse, keyboard, or similar input device.
The ZigBee Alliance developed ZigBee 3D Sync as a global standard that would make 3D video viewing more convenient, flexible, and enjoyable. Users wearing 3D glasses and using RF (rather than IR) can move around more without disrupting the 3D view. Instead of having to sit in a small sweet spot to get the 3D effect, they can sit anywhere on the entire couch. And viewers will find that head movement (unlike with IR) does not disrupt the 3D experience.
ZigBee 3D Sync also provides a standard for shutter management and will enable end users to share a single set of 3D glasses with a wide variety of brands and products such as game consoles, Blu-ray players, and 3D HDTVs. The standard will support variable display frame rates to ensure that the standard can be used with both existing and future display technologies. Plus, the standard will support multiple viewing modes and automatically adjust 3D glasses when content changes between 2D and 3D.
ZigBee Remote Control is designed to connect consumer electronics gear: TVs, home theater equipment, DVD and video players, set-top boxes, audio equipment, and similar products. ZRC establishes a global standard for advanced, greener, and easy-to-use RF remotes. ZRC removes line-of-sight restrictions while also delivering two-way communication, longer range of use, and extended battery life. ZigBee Remote Control can also be used to connect and monitor home sensing applications such as air conditioning and heating, home security sensors, and home health monitors.
Unlike IR remotes, ZigBee Remote Control also supports interactivity, which means that ZRC could support the use of small display screens on the remote that could show the volume controls of devices being controlled and which stations are being tuned. ZRC also makes it possible to set up and manage the recording of TV shows and movies on a DVR. Of special interest to the cable companies and service providers is ZRC support of interactive shopping and polling.
However, maybe the most appealing capability of ZRC is its ultra low power consumption. ZRC remote controls can be designed to last years without ever having to recharge or replace the batteries. In lab tests, a single coin cell type battery provides enough power to operate a ZRC remote for more than 10 years. Figure 2, courtesy of the ZigBee Alliance, shows how long a remote control will run (in days) using various technologies – IR only, using IR for TV communication and ZigBee Remote Control for the STB, and using only ZigBee for both TV and STB.
How to make ZigBee Remote Control (ZRC) even more powerful
It is possible to add technical refinements to ZRC that maintain compliance and interoperability with the standard as established by ZigBee while further improving robustness and ultra-low-power capabilities.
ZRC chips’ resistance to interference from 2.4 GHz networks such as Bluetooth and Wi-Fi can be improved by using two separate antennas to avoid typical indoor wave cancellation, thereby obtaining 300 dB (1,000x) better interference robustness compared to standard implementations. As more and more TVs and set-top boxes will be shipping with Wi-Fi Internet connections, diversity antenna robustness will become an essential component of an effective ZigBee Remote Control solution.
New chip architecture slashes power requirements even further
It is possible to reduce ZigBee RF4CE’s overall power consumption by 65 percent or more by using synchronized wake-ups (the communications controller determines when to wake up and check for messages) and a communication controller-centric chip design instead of a design centered on a microcontroller (MCU). Most transceiver solutions require that the MCU remain switched on during the entire transmission or the entire receiving of a package. Using a communication controller frees the MCU to process only the data to be transmitted or received, as Figure 3 illustrates.
Most low-power processor-centric radio designs require a microcontroller to handle all the intelligence for the transceiver, so the microcontroller needs to be awake the entire time, which requires additional power. Instead, by using a more energy-efficient communication controller approach, the transceiver can transmit and receive the data independently from the microprocessor. Thus the microprocessor is only awakened and used when it is needed to further process the data.
Because the communications controller decides when to wake up and check for messages (synchronized wake-ups, as noted earlier), the device can be off most of the time – thereby greatly reducing overall energy consumption. This is especially effective for the home’s various environmental, security, and location sensors. Because of the scheduler and synchronizer inside the communication controller, the system needs only to wake up for a brief moment to check to see if there are any messages and then goes back to sleep.
By using a hardware-based scheduler and synchronizer within the chip itself, the radio only wakes up as needed to see if there is any data that needs to be sent. If not, it returns to sleep. If there is data to be sent, the controller then wakes up the microcontroller. The chip communicates the information and then goes back to sleep until the next time it is scheduled to wake. You could have a situation, for example, where 9,999 times out of 10,000 times there is no message to be sent, and the controller does not need to energize the microprocessor. Every time that data is sent the chips also transmit a synchronization message to ensure that they all wake up together on the next duty cycle.
Figure 4 demonstrates how to greatly reduce overall energy consumption by letting the communication controller decide when to wake up and check for messages. Because the scheduler and synchronizer are inside the communication controller, the system only needs to wake up briefly to check for new messages and then it goes back to sleep.
Peak current savings – managing turn on and turn off
Figure 5 depicts the current consumption in three typical wireless sensor node states for a commonly used wireless sensor platform. In state one, the microprocessor and transceiver are in sleep mode (10 µA). In state two, the microprocessor is switched on while the transceiver is asleep (10 mA). In state three, both the transceiver and the microprocessor are awake (27 mA).
When closely examining the power consumption behavior of electronic circuits, it becomes apparent that what initially looks like a flat current curve actually bears more resemblance to a mountain range with peaks and valleys. When certain functional blocks become active, they draw peak current. When two functional blocks switch on simultaneously, the peak amplitude doubles.
The secret to reducing the peak power lies in carefully managing the turn-on and turn-off time for key functions so that double peaks can be avoided.
Faster, easier remote control development
Using pre-integrated ZigBee RF4CE chips targeting specific applications enables the fast and easy development of robust and low-cost ZigBee RF4CE remote controls. As the industry is still in the transition cycle between IR and RF, it makes sense to include the full IR functionality for use in legacy product designs as well as an embedded keyboard scanner for use in the remote control.
The ZigBee RF4CE chip for the remote control needs to have the best possible power optimization. While the ZigBee chip for the set-top box or TV set does not need to be optimized for power, the chip does need to offer the proper interfaces for easy integration. For TV sets, a UART interface is preferred, while for a set-top box, an SPI/TWI interface is preferred.
Bringing the complete RF4CE functionality for each application into a single device makes low-cost and reliable RF remote controls a reality. Pre-integration brings the cost of the total solution down and makes the choice for RF remote controls even easier.