Double the Protocols, Cut the Board Space: How Multi-Protocol SoCs are Simplifying IoT DesignSeptember 29, 2020 by Jake Hertz
Silicon Labs and STRATIS announced a collaboration to connect smart apartment complexes. What tech underlies this news?
Smart homes and smart-connected appliances have become all the rage in the past couple of years with companies like Amazon and Google investing serious money into the field. Underlying the emergence of these technologies are advances in wireless technology—one of the most impactful being multi-protocol chips.
A New Gateway Plus a Multi-Protocol SoC
The most recent news in the space of smart homes and IoT came this week when Silicon Labs and STRATIS announced their collaboration for a new smart home solution built specifically for apartment complexes.
The core device enabling this smart-apartment solution is the STRATIS Gateway 3.0, which is built for placement throughout apartment complexes to allow devices to send and receive data with one another.
The STRATIS 3.0 Gateway. Image used courtesy of STRATIS
Gateways are by no means new technology. But what makes this announcement newsworthy is what's happening at the circuit level. STRATIS teamed up with Silicon Labs to integrate Silicon Lab’s multi-protocol SoCs, most likely its Mighty Gecko SoCs, into the Gateway 3.0. This integration is said to equip the gateway with support for Bluetooth, Zigbee, Z-Wave, and LoRa connections.
Are Multi-Protocol SoCs a Game-Changer in IoT Design?
The field of wireless communications has seen some impressive growth in the past decade. Among this growth has been the development of many different communication protocols, from Bluetooth Low Energy (BLE) to Zigbee, all developed to serve different low-power connectivity needs.
Wi-Fi SoCs typically aren't included in edge devices because these devices, usually equipped with small batteries, can't handle the high power consumption of Wi-Fi. A Digi-Key article on multi-protocol, multi-band SoCs notes that Wi-Fi's "primary use in IoT has been for backhaul and gateway-to-internet access where power consumption is not a crucial metric."
Previously, the main design issue with multiple protocols was board space: engineers needed a separate chip for each separate protocol. Only in the past couple of years has this issue been addressed with companies like Silicon Labs, Nordic Semiconductors, Texas Instruments, Analog Devices, and others developing lines of multi-protocol SoCs and transceivers.
Block diagram of Silicon Labs' multi-protocol chip, the Mighty Gecko SoC. Image used courtesy of Silicon Labs
These multi-protocol devices have the ability to communicate across multiple RF bands, allowing for the use of multiple communication protocols and greatly simplifying the deployment of wide-scale IoT networks. Additionally, combining a number of protocols into a single chip saves board real estate and cuts down on a designer's BOM.
Currently, there are no chips that support all of the wireless protocols within the IoT sphere.
Different Types of Multi-Protocol Connectivity
Silicon Labs outlines several types of multi-protocol connectivity, including programmable multi-protocol, switched multi-protocol, dynamic multi-protocol, and multi-radio multi-protocol.
Programmable multi-protocol allows designers to program a chip in production to a certain protocol—even proprietary protocol—via a software stack.
A switched multi-protocol option allows a device to switch which wireless protocol it is using by bootloading a new firmware image while being deployed. This protocol also responds to over-the-air updates.
Diagram of a switched multi-protocol solution. Image used courtesy of Silicon Labs
A dynamic multi-protocol uses multiple wireless protocols simultaneously by implementing a time-slicing tool to share the radio.
Diagram of a dynamic multi-protocol solution. Image used courtesy of Silicon Labs
Finally, a multi-radio multi-protocol can allow a network stack to operate across two radios, sometimes using two completely different frequency ranges. This allows a device to operate a number of protocols without forfeiting any benefits of each respective protocol.
Other semiconductor manufacturers have analogous multi-chip connectivity. For instance, TI offers a concurrent multi-protocol option on a single chip, a "swapped" multi-protocol option (also called "provisioning"), and a coexistence multi-protocol, which involves two chips.
Under The Hood of Multi-Protocol SoCs
Without getting too deep into the technical details (especially since each manufacturer has its own unique multi-protocol architecture), it’s important to understand some of the working hardware blocks in a multi-protocol SoC.
Typically, these SoCs include a baseband section and an RF section based on the IEEE 802.15.4 physical layer wireless interface. The structure of these SoCs is designed to address the challenges of a transceiver that operates across a wide range of RF frequencies.
Block diagram of TI's CC26xx series of SimpleLink SoCs—an example of a multi-protocol SoC architecture. Image used courtesy of Texas Instruments and Digi-Key
An Arm host processor and coprocessor are generally central components, accompanied by some degree of encryption and a true random number generator for security. Also included are power and sensor management circuits, multiple clocks and timers, and several I/O options.
Doubling Up on Protocols Save Board Space
In the past, designing an IoT with built-in multi-protocol support could be a complex, space-constraining process. In the past few years, however, multi-protocol chips, like this recent integration of Silicon Labs' Mighty Gecko SoCs into the STRATIS 3.0 Gateway, has remedied that pain point.
Still, while such chips can help designers build backward-compatible devices in the future, legacy devices will simply not be compatible with newer devices using emerging protocols.
Do you design in the IoT space? If so, do you consider multi-protocol chips a game-changer in your design process? Share your thoughts in the comments below.