How does the home IoT design realize multi-mode wireless connection?

“Internet of Things (IoT) designers can design in response to various application requirements, but more and more people are not satisfied with a communication protocol that supports only one wireless connection technology. This situation is most common in smart homes, because the lack of standards (or more precisely, they are actually too many) makes products must be connected in various ways. Even some industrial systems can take advantage of multi-mode wireless technology. These conditions are driving the demand for processors with multiple wireless functions.

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Internet of Things (IoT) designers can design in response to various application requirements, but more and more people are not satisfied with a communication protocol that supports only one wireless connection technology. This situation is most common in smart homes, because the lack of standards (or more precisely, they are actually too many) makes products must be connected in various ways. Even some industrial systems can take advantage of multi-mode wireless technology. These conditions are driving the demand for processors with multiple wireless functions.

The Nest Protect smoke detector is a good example. It uses Wi-Fi to connect to the router at home, and the device also includes a Bluetooth (Bluetooth) radio, allowing users to configure the product directly from a mobile phone or tablet before installation. During a power outage, this battery-powered device uses a proprietary 802.15.4 protocol-Nest Weave, to continue to communicate at home, and users can set the phone’s alarm clock to mute via Bluetooth. This combination of multi-mode wireless technologies ensures optimized connectivity while shifting to the lower power consumption 802.15.4 protocol to extend battery life.

Nest Protect smoke detectors are interconnected via the 802.15.4-based wireless protocol Nest Weave, and connected to the router at home via Wi-Fi. It can also be controlled via the Bluetooth function of a smartphone. Smart door locks usually include a camera. Let the user see who is at the door before deciding whether to open the door lock. Just like smoke detectors, door locks are usually controlled via Zigbee or Z-Wave (both 802.15.4 variants), and can be operated even during power outages. But these simple interfaces do not have the bandwidth for video, so the camera is usually connected via Wi-Fi.

Smart home gateways usually include multiple protocols. These gateways are usually integrated in the control panel and serve as the hub of various IoT devices. For example, the XFinity Home platform provides a touch panel that uses Wi-Fi to connect to the Internet and surveillance cameras, but connects to security sensors and other smart devices through Zigbee. Some models also include a cellular modem, so even if the Internet connection is interrupted, emergency alerts can still be sent. The gateway can also be used as an independent device, such as the Wink Hub, which can communicate via Wi-Fi, Bluetooth, Zigbee, Z-Wave, Thread, and other protocols.

Although the industrial environment can be better controlled, factory facilities will usually end up using multiple IoT systems with different protocols. For example, a smart lighting system may use Zigbee, while asset tracking relies on Bluetooth. This mismatch often occurs when the system is installed by different departments at different times. In these cases, multi-protocol gateways can simplify the data collection and control of the Internet of Things. Just like consumer devices, adding Bluetooth makes it easier to configure and manage industrial IoT devices on mobile phones or tablets.

Adding multiple wireless chips to a basic microcontroller (MCU)-based design can make it very complicated and costly. One of the better solutions is to choose a multi-protocol IoT processor. For example, Qualcomm’s QCA4020 combines the Cortex-M4 subsystem and three wireless protocols such as Wi-Fi, Bluetooth and 802.15.4. Although some system designs may omit 5GHz antennas to reduce costs, in order to achieve the best performance, this chip uses a dual-band (5GHz/2.4GHz) 802.11n Wi-Fi design. The chip also built the latest Bluetooth 5 protocol, which can expand the range while connecting to compatible devices, and it also supports the new Bluetooth mesh protocol.

These three wireless technologies integrate baseband, transceiver and amplifier (PA/LNA), thereby reducing BOM. The chip includes a dedicated CPU and memory, as well as a second CPU and memory, used to process Bluetooth and 802.15.4 MAC, offload these tasks from the main Cortex-M and improve security. The hardware coexistence engine helps Wi-Fi and Bluetooth MAC to coordinate the use of 2.4GHz antennas to avoid degrading the performance of systems that support separate wireless chips.

Cortex-M4F CPU operating frequency is up to 128MHz. In addition to the 32KB L1 cache, the CPU can also utilize on-chip SRAM. Even if the basic RTOS and drivers are loaded, the memory leaves more than 300KB of space for the application without using external DRAM. However, QCA4020 relies on external flash memory to support the execution-in-place (XIP) protocol for QSPI connections. The chip also includes a security engine and general-purpose edging equipment, including serial ports, A/D converters, and USB 2.0.

Compared with many vendors on the market that provide MCUs that integrate one or even two wireless protocols, QCA4020 is a 3-mode IoT processor. As more and more IoT designers try to add multiple wireless protocols to the system, this type of microprocessor will help simplify their bill of materials (BOM) and shorten design time.