"Due to the continuous innovation, there are many incompatible wireless options in the IN application. Although there is always a good thing, this also makes the deployment of wireless networks - especially for old industrial materials Networking (IIOT) equipment, which may have deployed multiple wireless networks, and now you need to add hundreds of sensors in multiple facilities.
To solve this problem, the Internet of Things transceiver manufacturers have developed low-cost, low-power-on-chip-on-Solutions, which support multiple protocols across multiple radio frequency bands in a single device.
This paper briefly introduces the design challenges of widely used in a wide range of short-range wireless communication standards and norms. It will then be described that allows designers to flexibly deal with NXP, Texas Instruments, Silicon Labs, and Analog Devices chip systems (SOC), and explore the functionality of these devices and wireless protocols they support.
Wireless selection challenge
Just a few years ago, there were few Internet transceivers or microcontroller SOCs that support multiple wireless protocols, so the manufacturer of edge devices selected a protocol and used throughout the product line. For example, in home automation, this is the first Internet of Things application, "intelligent" lighting product manufacturer may use Zigbee, and another may use Z-Wave, and another Wi-Fi can be used. The new technologies that have been very complex are more confusing for consumers.
Industrial Internet of Things market is now facing the same challenge, but it is much more much on scale. Unlike geographical upper bound families, large manufacturers' plant facilities may be globally, and various equipment and regulatory requirements can be supported. The appearance of multi-protocols, multi-band transceivers and microcontroller SOCs allow engineers to deploy such devices, systems, and network architectures easier. As these SOCs are increasingly used for edge devices, the network that uses SOCs from a single vendor in the edge device to support multiple wireless protocols will be possible.
Typical Internet of Things SOC Features
Typical SOC of the Internet of Things includes a baseband and a radio portion based on an IEEE 802.15.4 physical layer (PHY) wireless interface for low-rate wireless personal local area network (LR-WPAN); an ARM main processor and coordinator; The degree of encryption, such as AES-128; and a true random number generator (TRNG). In addition, a power supply and sensor management circuit, a plurality of clocks, and a timer, and multiple I / O selection (Fig. 1). Since ZigBee has become a very popular protocol in industrial applications, there is almost universal support in these devices, and there are similar low data rate protocols, such as Thread.
This example also includes low power Bluetooth (version 4), and more and more products support Bluetooth 5 (version 5.1). The mesh network is adopted in the Bluetooth 5.1 to make it a strong competitor in the large-scale network. However, not all SOCs support this version, so it is important to determine whether the alternative device of the industrial network is supported 5.1.
Some devices also support IPv6 low-power wireless personal local area network (6LowPan), which is an open standard for the Internet Engineering Task Group (IETF) based on 802.15.4 PHY definition. 6LowPan joins the standard TCP / UDP on IP header compression (IPHC), 802.15.4 PHY and Media Access Control (MAC) required for IPv6, and can be 900 MHz (or lower) and 2.45 GHz Under the frequency.
The uplink to the Internet is processed by an IPv6 edge router that is also connected to multiple PCs and servers (Figure 2). The 6LOWPAN network itself uses its own edge router to connect to the IPv6 network router.
One of 6LowPan is a feature that it is capable of delivering end-to-end packet delivery anywhere using a standard Internet protocol, which enables designers to use advanced messaging protocols such as MQTT, COAP, and HTTP in all applications.
Like other protocols mentioned herein, in addition to 2.4 GHz, the protocol can also be run on the "secondary 1 GHz" radio, so it has good propagation characteristics. For example, the related presentation of 6LOWPAN indicates that the coverage of 900 MHz is over 4 miles at 900 MHz when the radio frequency output power is +12 DBM. The low frequency is particularly useful in the room because they have better wear wall capabilities. After properly configuring and uses the right bridge, 6LowPan can interoperate with any other IP network (such as Ethernet, Wi-Fi or cellular data network).
Basic agreement
Currently, there is no SOC support for all wireless protocols used in the Internet of Things. This is not particularly important for designers for industrial network networks, as some protocols (such as Thread and Z-Wave) have been widely used in the consumer market. This reduces Zigbee (the most popular protocols in industrial networks so far), and competitors of 6LowPan and Bluetooth. That is to say, any SOC that supports 802.15.4 should be able to use ZigBee, LPWAN, Thread, and possible proprietary solutions that can work in the same frequency band.
For low-power edge devices that use micro-battery powered, multi-protocol SOC usually does not include Wi-Fi because its power consumption is high. In the Internet of Things, the main use of Wi-Fi is the backhaul and gateway to the Internet to the Internet. However, since the high data transmission rate is high and almost everywhere, Wi-Fi is essential when urban upgrade lighting, monitoring, and other infrastructure.
For these applications, on-chip Wi-Fi So has been introduced for many years, and because the technology is an indispensable part of the Internet of Things applications that require high data rates, their applications are growing. One of the SOCs that only support Wi-Fi is the CC3100R11MRGCR Wi-Fi network processor of Texas Instruments, which has 2.4 GHz Wi-Fi radio and network processors and on-chip web servers and TCP / IP stacks. When used in combination with microcontrollers from Ti or any manufacturer, the SOC can form a complete Wi-Fi solution in two small devices.
Even so, quite many SOCs support Wi-Fi and Bluetooth protocols simultaneously, because the two protocols are very popular and complementary. For example, WiLink 8 Wi-Fi / Bluetooth combination module in Texas Instruments supports Bluetooth and low power Bluetooth. For Wi-Fi, the product includes IEEE 802.11b / g / g (maximum data transfer rate of 100 megabits [MB / S]) and Wi-Fi Direct. The module has 2 x 2 MIMO capabilities, coverage is 1.4 times the single antenna device, and the power consumption is less than 800 microam (μA) in Wi-Fi mode. The Bluetooth function complies with the Bluetooth 4.2 security connection standard, which also includes a host controller interface for transferring Bluetooth data via UART, and an audio processor that supports Bluetooth Advanced Audio Distribution Specification (A2DP) sub-band decoder.
In a package of 13.3 × 13.4 × 2 mm (mm), RF power amplifiers and switches, filters, and other passive components, and power management and other resources, such as 4-bit SDIO host interfaces.
Silicon Labs Mighty Gecko EFR32MG13P733F512GM48-D Multi-protocol SOC uses an interesting method to combine the microcontroller with transceivers operating at key frequencies between 169 MHz and 2.450 GHz. This makes it compatible with low power Bluetooth and Bluetooth 5.1, Zigbee, Thread, and even 802.15g. 802.15g is a standard variant designed for ultra-large utility applications in smart grid networks, which may have millions of fixed endpoints in a widely dispersed region.
In the Mighty Gecko series, some devices support networks operating below 1 GHz, allowing for specific applications to be customized to support various modulation schemes, such as OOK, shaping fsk, plastic OQPSK, and DSSS modulation.
The SimpleLink platform of Texas Instruments includes a variety of hardware, supports low-power Bluetooth and Bluetooth 5.1, Thread, W-FI, Zigbee, and "6LoWPan" solutions (such as 6LowPan), and Wired standards such as Ethernet, CAN and USB. . According to models, such devices support two or three wireless protocols. Each model in this series can be supported in a single software development environment.
For example, the CC2650F128RHBR SIMPLINK multi-standard wireless MCU includes support for Bluetooth, ZigBee, and 6LowPan, and support for remote control applications such as ZigBee Consumer Electronic RF (RF4CE). The latter protocol is the enhanced version of IEEE 802.15.4, with network layers and application layers to create multi-vendor interoperable solutions. The CC2650 uses 32-bit ARM Cortex-M3 as the host processor for use with the power sensor controller, even if the entire system is in sleep mode, the sensor can operate independently. Bluetooth controllers and 802.15.4 Mac use a separate ARM Cortex-M0 processor to release memory to support applications.
NXP Semiconductors MKW40Z160VHT4 SOC supports low-power Bluetooth and 802.15.4 standards for ZigBee and Thread, operating frequency between 2.36 GHz and 2.48 GHz, and use ARM Cortex-M0 + CPU, Bluetooth link hardware and 802.15.4 Packet processor. In addition to the main subsystem, the So can act as a modem to add Bluetooth or 802.15.4 to an existing embedded controller, or in embedded applications without host controllers. Separate wireless sensor.
Analog Devices' LTC5800IWR-IPMA # PBF Multi-Protocol SOC also supports the AGM-based 802.15.4 protocols described above, and another agreement with interesting history named Smartmesh. The protocol was developed by the Electrical Engineering and Computer Science of Berkeley, California, USA, developed in the 1990s and got funded by DARPA's Smart Dust project. The goal of the project is to create a micro, highly reliable radio that can be supplied by a battery or through energy. The main customers will be a widely distributed pipeline utility department, and the work environment conditions are usually very bad.
In order to commercialize this technology, Pister jointly founded Dust Networks to create a network wireless sensor network called SmartMesh. In 2011, the company was acquired by Linear Technology, Linear Technology itself was acquired by Analog Devices in 2017. Smartmesh is here, and now also applies to industrial Internet of Things.
Smartmesh contains a self-formed multi-hop node (called dust) network for collecting and relaying data; and a network manager, responsible for coordinating performance and security with host application (Figure 3). Since reliability is one of the core requirements of the Darpa project, even in harsh environmental conditions, SmartMes can remain 99% of normal running time. Its communication protocol is a spread spectrum, referred to as a slot channel hopping (TSCH), can synchronize all the dust in the network into a few microcodies.
All dust in the network can be synchronized to less than 1 millisecond (MS), and the battery life can exceed 10 years. You can create a complete wireless node for power supply to decoupling, crystals and antennas. When using a full-to-2 DBI gain antenna, the typical coverage of the LTC5800-IPM is 300 meters (m) and 100 m in the room.
Summarize
Since there are many variations versions of wireless protocols, plus some legacy systems may need to support, so it is difficult to choose to choose the right wireless interface and protocol when deploying industrial network. As mentioned above, Internet SOCs that support multiple short-range wireless protocols across multiple radio frequency bands have greatly simplified the deployment of industrial networks by bringing greater flexibility to designers.
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