The real deployment phase of the personal LAN (PAN) has not yet arrived. We are in a new generation of wearable computers, sensors, and peripheral explosions points, which will enable us to entangle the entanglement of the machine into a new level.
Traditionally, a PAN will associate with a wireless voice link, such as a Bluetooth connection with a wireless headset. Although this is a useful local machine to machine (M2M) personal link, it is far from reaching the actual potential to be available in low power RF near field technology PAN.
This article will explore what choices we have to generate and send and receive data through our "personal electromagnetic bubble". The low-power level and signal type used in various applications will be discussed, and the scope covers the wearable device or a simple "deep embedded" sensor to more complex HD video and image processing for real-time 3D gesture recognition.
We will discuss which standard chip-level solutions today, such as IrDA, wireless USB, Bluetooth, Z-Wave, ZigBee, and Wi-Fi, and research from the perspective of bandwidth to determine the actual expectations that can be seen. Throughput. At the same time, we will also discuss which standards are better for different functions. All parts, specifications, guides, and development tools cited in this document can be found in the Digi-Key website.
Not all RF
Wireless links generally make us associate radio concepts, but not all wireless links are based on RF. Some sights, proximity and low bandwidth communication can be replaced by IR (infrared). For example, two pieces of feedback gloves for remote control of devices or medical programs. At this point, it is better to do better like RoHM RPM973-H11E2A (Fig. 1). Such transceivers are ultra-thin, self-sufficient, and can provide up to 4 Mbits / s speeds with optical links without any source of environmental radio frequency noise interference. It has a strong structure suitable for harsh conditions.
Although optical technology has its own unique, so far, the most widely used communication technologies are used in emerging PAN applications or RF. Interestingly, for higher-range low-speed links, low-cost narrowband AM, FM, ASK, FSK, carrier open / carrier and PSK type RF are used. The computer mouse has 1,200 bit / s data speed can be working very well.
MURATA TR3000 uses 433.92 MHz carrier and ASK or OOK modulation, supports up to 115.2 kbaud data rates. Its operating voltage is 2.7 to 3.7 V, and the current is only 3.8 mA, and the current can be transmitted for only 3.8 mA, 7.5 mA. Its energy consumption is more good, and the energy consumption of the short-range link can be reduced to a quantity level, thereby extending battery life (Figure 2).
Although the narrowband AM and FM can be power limits, there is too much possible interference source, so such links generally do not perform arbitration, conflict detection, conflict avoidance and automatic retransmission. It is better to use digital radio at this time.
Multiple digital criteria are competing for a coveted large-scale PAN market, including uniform interoperability standards such as Bluetooth, USB, ZigBee, Wi-Fi or Z-Wave, inadvertent.
With multiple IC-level devices, wireless USB will provide some guarantees. CYPRESS CYRF6936-40LTXC is a direct sequencing spread spectrum wireless 2.4 GHz USB transceiver only parts. 1.8 to 3.6 V The data speed of up to 1 mbit / s, setting and control using 4 MHz SPI ports. This is a 40-pin part with a nude solder, slightly larger than a narrowband solution. Its 34 mA launch (21.2 mA reception) current is also significantly higher. In fact, many applications are in a sleep state rather than awaken, and use small batteries to achieve long-term communication, if the battery can charge, it is especially true.
Similar parts with embedded controllers include CyPress Cyrf89235-40LTXC that provides a piece-up Harvard architecture M8C RISC processor with up to 24 MHz, and an emulation port (Figure 3). The film 32 k flash memory can store stacks and user code for certain applications. 2 K RAM can be extended on programmable I / O by an 8-bit port or by an I2C or SPI interface (both also include).
Not just voice
Bluetooth Voice Future is most likely to rule the headset sector or for personal voice links, although there are many powers it uses far than they need. For most parts, Bluetooth devices will work well together, even in crowded environments. The network sharing process will make the transceiver a simple query lock type without maintaining multiple sockets and complex protocol stacks.
On the other hand, low-power Bluetooth is ideal for non-voice applications such as image sensors, actuators, and PANs. Similar to other criteria, some people have begun to initiate an integrated solution. A Bluetooth Le solution worth noting is from CSR, ie, its TCSR1010A05-IQM-R single-chip Bluetooth Le handle system (SOC) transceiver (Figure 4). As part of the CSR's μnergy low-power Bluetooth platform, the device simultaneously contains an embedded microcontroller. In this example, a 16-bit RISC processor running a BT Le stack, radio, interrupt, and external interface.
It should be noted that these parts have more resources available. Flash and RAM capacity are 64 k bytes. In addition, these parts include a 10-bit A / D, 12 programmable I / O, SPI, I2C, UART, PWM, and a debug SPI port. For radios currently under development, almost all have energy management characteristics, and 32 kHz real-time clock crystals can be used to save more sleep power.
Another competitor in this field is STMicroelectronics, which provides Bluetooth Le Wi-Fi Network Processor BluenRGQTR. It is also a 1 mbit / s compatible master, which is also compliant with the Bluetooth V4.0 specification requirements from the device. It can use a 32 kHz clock or oscillator to reduce energy consumption or run on a higher native frequency to perform process-intensive data processing. In this example, the frequency is up to 32 MHz.
It is based on the ARM Cortex-M0 processor (Figure 5), with a 64 k program flash memory and 12k SRAM. It also has SPI, I2C, UART, serial programs and debugging, and AES hardware. STMicroelectronics is a potential peripheral controller in the PAN field, especially suitable for health care applications. The company also provides product training modules for the health applications of Bluetooth Le.
Similar to many other vendors, StMicroelectronics also supports stacks and provides development environments to help you accelerate the development speed. In this example, the supplier's Steval-IDB002V1 is a useful presentation and evaluation board for Bluenrg low power network processors.
Other possible
Other wireless players want to have a cup of obstacles to overcome a cup in the PAN market in the outbreak growth stage. One of the examples is ZigBee. This is a popular standard, with multiple equipment and module manufacturers support, suitable for family and building automation.
Unlike Bluetooth, Zigbee has no native support on smartphones, tablets, and laptops. This may have obstacles. ZigBee also requires a fairly complex stack that means that the node cost will be higher. On the other hand, ZigBee has architectural arbitration and identification capabilities that have advantages in part of the big mesh.
Wi-Fi is also certain attractive places, especially in promoting the Internet of Things. It provides cloud based connectivity, and the chips and modules there are also solutions for authentication and ready-to-use. Although Wi-Fi has native support on smartphones, tablets, laptops, but power consumption is too large. In terms of control flexibility, it may not be a PAN application, so it may still be a viable solution, especially after it enters the low power mode, you need to re-establish the connection when waking up, and the discovery mode also takes a lot. Time and energy consumption.
There are other potential solutions. Z-Wave, Ant +, IOHomeControl, W6lopan and RF4CE are all applying specific and general protocols, which is worthy of understanding.
All in all, we are witnessing the rapid development of new generation of materials related products, which will enhance our ability and our self-awareness. In this environment, smart phones are most likely to be a central center of personal LAN, which connects to the health care monitor, smart watch, and display devices (such as Google glasses) and various embedded clothes and shoes sensors. . This paper explores what selection of engineers have to generate and receive data through personal "electromagnetic bubble". We also discussed many possible agreements and reviewed representative parts.
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