Talk about the future of ultra low-power RF technology

Although there are a few deliveries of ten million per week , but in the world of popular 2.4GHzISM band low-power short-range radio technology markets ( such as Wi-Fi, Bluetooth , ZigBee and proprietary solutions each company ) is far mature. In the next few years, there will be a lot of encouraging progress , and the wireless connection will permeate every aspect of our lives.

Especially in the ultra-low power (ULP) wireless application system, which uses button battery powered miniature radio transceiver , sending " pulses" to wake up quickly after the data , and then back nanoampere level "sleep & rdquo ; the state , which is likely to be substantially increased . For example , according to ABI Research analysts pointed out : In 2010 , wireless sensor networks (WSN) chip market grew by three hundred percent . The company also predicted : in 2016 , the use of medical care and personal fitness equipment deliveries Bluetooth low energy chips will not be less than 467 million .

Can any portable electronic products or devices ( from tiny medical sensors and fitness sensors to mobile phones, computers , machine tools, automobiles, almost everything between them ) embedded electronic circuits , ultra-low power wireless can put connections added . Use tiny ultra-low power transceivers , these electronic products or devices to communicate directly with thousands of other devices , or as part of a network for communication , significantly improve the usability of electronic products.

However, for most engineers, RF design is still difficult to grasp. Although the RF design is not a trivial matter , but with the help of a very good chip vendors and tools under development that it does not exceed a competent engineers design skills . Therefore, in this article, I will unveil ultra-low power wireless technology , introduced the chip , and to explore how and where to use these chips .

Ultra-low -power wireless technology Introduction

Ultra-low -power wireless technology and Bluetooth technology ( now called Classic Bluetooth , to distinguish it from the recently released version 4.0 of Bluetooth , including ultra-low -power Bluetooth low energy technology ) these distinctions low-power short-range radio technology that it obviously needs a lot less power . Thus , the opportunity to use a wireless connection in the smallest and most compact portable electronic devices , it is greatly increased.

Classic Bluetooth requires more power , even if the amount of user data transmitted and therefore almost exclusively use rechargeable batteries. It requires a higher power for low bandwidth , long-life applications, then it means that the traditional wireless Bluetooth is not a good solution ( which can easily be primarily in charge when the battery is often used bulk transfer of data ) .

Bluetooth wireless technology has been used in a typical between mobile phone and headset connection, or digital camera to transfer images to a Bluetooth printer. Therefore, using a typical Bluetooth wireless devices , battery life that is usually a few days up to a few weeks ( Note: Some typical Bluetooth highly specialized applications, lower capacity can be used for primary batteries ) .

In contrast, ultra-low power RF transceiver can be used button batteries ( eg CR2032 or CR2025) power supply , working for months or even years ( depending on the duty cycle of the application system ) , assuming that the average current consumption is rated only 200 & mu ; A. These small button batteries , cheap , but the energy is limited, typically in the range of 90 to 240mAh ( one AA battery button battery capacity is 10 times to 12 times ) .

This capacity is moderate , significantly limiting the ultra-low- power wireless link active duty cycle. For example , a 220mAh CR2032 coin battery , if you want it to continue to work for a year , then its maximum rated current ( or discharge rate ) can only be maintained at 25μA (220mAh / (24小时x 365天) ) . Peak current ultra low power radio frequency technology, tens of mA, for example , Nordic Semiconductor nRF24LE1 2.4GHz transceiver when 11.1 mA emission current consumption ( output power of 0dBm ) when receiving current consumption 13.3 mA ( working at 2Mbps when ) . If the average current for an extended period is limited to tens of microamps , the duty cycle must be very low ( approximately 0.25% ) , and the chip to quickly return to sleep mode , consuming most of the time only a few cents microampere current.

talked about a variety of different uses ultra-low power RF technology in the future

If the transceiver accounted for 99.75% of sleep time , wake up when it is something to do anything useful , it must be very hard work . Ultra-low -power transceivers do so : it wakes up quickly , sending a short but relatively wide bandwidth of the "pulse " of data ( up to 1 or 2 Mbps), and then immediately return to low energy sleep state.

As we have seen , because they belong to moderate power consumption , ultra-low power RF transceiver can not be used for high duty cycle applications , therefore, does not directly compete with Wi-Fi and classic Bluetooth. However , ultra-low power operation really opens up a broad new application areas that other wireless technologies can not.

Diversification of these uses are not unusual. Ultra-low -power wireless technology has entered the sports , health , entertainment, PC peripherals, remote controls, games, mobile phone accessories, home automation and industrial control field, but in the next few years will spread to many other areas.

These applications have one thing in common , which uses the advantages of ultra-low- power wireless technology. They are built using a small battery -based compact sensors and peripherals above . These devices send small amounts of data ( usually several ) , but not often send ( every few seconds or up to several times per second ) . Despite the similarities , it has a variety of different purposes , for example for wireless computer peripheral devices ( e.g., wireless mouse ) , and the associated code table bicycle sensor performance ( e.g., speed and distance monitor ) , a radio frequency remote control, the medical sensor ( eg heart rate monitor ) , they require very different engineering solutions.

Briefly, the RF system requires a wireless connection (transceiver ) , protocol ( software code or "stack" , which controls how the radio communication system ) , but also an application processor ( which has its own code, monitoring specific applications, such as heart rate monitor ) . However , how to implement these things , will affect the efficiency , size and cost of wireless systems.

To illustrate this point , let's look at two examples : a wireless mouse , a bicycle stopwatch, they use different methods.

Wireless mouse is a relatively simple ( but certainly not insignificant ) , ultra-low power RF applications heavily used . Wireless mouse manufacturers need a compact, high- efficiency , inexpensive connectivity solutions . In other words , they want their beautiful shape wireless mouse , battery life is very long, the retail price to consumers can afford .

Mouse is the best choice for system chip (SoC), which includes the RF system , the plant provides protocols and application processor , all in a piece of silicon. Because of the large amount of it to offset the higher development system chip non-recurring engineering (NRE) costs. In addition, manufacturers can optimize the performance of hardware and software to meet the needs of the target application .

For customers ( mouse manufacturer ) , the main advantage is that they do not have to choose and buy an external processor ( and the corresponding development tools ) in the development , and then generate the code to run the application , do not have to spend time and money in these areas . Transceiver vendors have made ​​some of SoC design work . ( However, if desired, customers can still use development and evaluation tools transceiver vendors to develop their own protocol .)

For example , Nordic Semiconductor offers nRF24LE1 system chip peripherals to the desktop computer market . This nRF24LE1 contains Nordic nRF24L01 + 2.4GHz ultra-low power consumption of the transceiver , Gazell software stack ( stored in flash memory or one-time programmable (OTP) memory ) and an enhanced 8-bit microcontroller . This monolithic device is only the size of 5 × 5 mm, you can use it to design the smallest wireless mouse .

nRF24LU1 + is another system chip , which integrates the Nordic nRF24L01 + transceiver is compatible with USB 2.0 device controller , flash memory ( or OTP memory ) , 8-bit microcontroller , insert it into the "host" computer's USB port , a wireless connection is completed . Use nRF24LU1 +, PC peripheral manufacturers can create tiny USB adapter , it barely extends beyond the USB port on the host.