Wireless MCUs: Enabling the Interconnected World

Published:September 21, 2023

Prof. David Reynolds stands as a luminary in the field of electrical engineering, renowned for his expertise in integrated circuits. Holding a distinguished position as a Professor of Electrical Engineering, Prof. Reynolds earned his acclaim through decades of research, teaching, and industry collaboration.

Benefiting from the rapid growth in the number of interconnected nodes brought about by the development of the Internet of Things (IoT), the deployment of wireless MCUs has become a strategic focus for many MCU manufacturers. Most MCU manufacturers have entered the wireless MCU product line, each with its unique features, as no one wants to lag behind in the vast IoT market.

In today's era of ubiquitous connectivity, wireless MCUs combine radio frequency (RF) wireless with software-defined digital control through highly integrated solutions, solving the problem of interconnection. Wireless MCUs can integrate or provide relevant communication protocol stacks, simplifying the development and design of wireless IoT products.

From MCUs to wireless MCUs: Facilitating the ever-evolving interconnected world

With the rapid development of IoT technology and downstream applications, the number of wireless interconnected nodes is growing at an astonishing rate. In our daily lives, an increasing number of interconnected scenarios are becoming popular and applied. In the age of interconnection, every node requires reliable connectivity, which not only demands stable and fast connections but also needs to be flexible enough to meet various wireless protocol and range requirements.

Previously, the RF chips we were familiar with were mostly pure RF transceivers. However, wireless modules without MCUs were just wireless front-end modules that could not be used independently and required users to write programs to drive them. In today's rapidly growing IoT device market, this method of using MCUs and wireless modules separately is time-consuming and requires a certain level of development experience.

The IoT market demands various wireless technologies, and in terms of signal acquisition or control units, MCUs are indispensable. SoC chips with wireless and MCU integration have definite advantages in terms of BOM cost and board size. Transitioning from MCUs to wireless MCUs, developers can easily perform secondary development based on SDK, which no longer poses obstacles for developers. Most developers already have the capability to independently develop wireless MCUs, making a smooth transition from MCUs to wireless MCUs.

In wireless MCUs, the control program within the wireless module is written and burned into the MCU, enabling direct communication without the need for additional tools, simplifying the development and design of wireless IoT products. With these advantages, wireless MCUs bring more opportunities to wireless connectivity for IoT terminals in a more convenient way, increasingly used in various terminal applications.

Vast market space and continuous growth of wireless MCUs

Wireless connectivity technologies mainly include local wireless communication and wide-area wireless communication. Local wireless communication technologies primarily include WiFi, Bluetooth, ZigBee, and others. Wide-area wireless communication technologies are divided into non-licensed spectrum technologies such as LoRa, Sigfox, and cellular communication technologies like NB-IoT, which operate in licensed spectrum.

Local wireless connectivity technologies, characterized by small module size, high integration, and low power consumption, are more suitable for IoT smart industry applications such as smart homes, wearable devices, new retail, and health care.

In terms of wireless frequencies, 2.4GHz and Sub-1GHz are the two main frequency bands used by wireless MCUs, with very few using Sub-1GHz & 2.4GHz. Well-known wireless technologies like Bluetooth and Zigbee operate in the 2.4GHz frequency band. Products that use Sub-1GHz & 2.4GHz across the full spectrum are currently relatively rare.

Looking at products on the market, Bluetooth technology is the most widely used in general standard protocols, especially low-power Bluetooth technology. All the advantages of Bluetooth can now be integrated into wireless MCUs, effectively providing a simple single-chip solution for interconnected applications.

Classic Bluetooth, low-power Bluetooth, and the combination of both in dual-mode Bluetooth wireless connectivity technology can currently meet a wide range of connection requirements. The Bluetooth Special Interest Group (SIG) predicts a significant increase in shipments of these three modes in the next five years. In particular, the growth of low-power Bluetooth single-mode devices is rapid, with shipments expected to triple during this period. It is estimated that by 2027, the annual shipment volume of low-power Bluetooth single-mode devices will be on par with that of dual-mode Bluetooth devices. This also means that the shipment volume of Bluetooth wireless MCUs will continue to rise in the future.

The application of 2.4GHz proprietary protocol wireless MCUs is also widespread. Many popular applications, such as wireless mice and keyboards, smart remotes, smart lighting, and similar applications, use 2.4GHz proprietary protocol wireless MCUs. Electronic shelf tags are also a typical application area for 2.4GHz proprietary wireless connectivity chips. The continued growth of these markets will provide ample development prospects for wireless MCUs.

Low-power competition and increasing integration

In addition to protocols, many devices in the IoT scene are highly sensitive to power consumption. Therefore, power consumption has always been a critical performance factor for wireless MCUs, especially in applications with limited space and battery power, where long working hours are required, imposing stricter power consumption requirements.

Taking TI's latest pre-released multi-protocol, multi-frequency band Sub-1GHz and 2.4GHz wireless MCU CC1354 series as an example, it achieves concurrent multi-protocol through a dynamic multi-protocol manager driver. In terms of power consumption, the series has been optimized, with MCU power consumption only 71µA/MHz when running CoreMark, with a low standby current of 0.83µA with full RAM retention and power consumption as low as 0.17µA in shutdown mode with pin wake-up. Radio power consumption has also been optimized.

ST's STM32WB series also follows an ultra-low power consumption route, with current consumption of less than 53µA/MHz when RF and SMPS are active, resulting in extremely low power consumption. Silicon Labs' 32-bit wireless MCU EFM32 series achieves power optimization in active mode to 26µA/MHz under 80 MHz conditions.

To meet the demands of the IoT market, integrated wireless MCUs with internal features that add value are required. Increased added value can be achieved through higher integration. Most wireless connectivity chips are in SoC form, and from an intuitive perspective, products with high integration save customers the cost of peripheral components and reduce product size. At a deeper level, because the product positioning and target application are relatively clear after integration, the optimized integrated functions make it easier to use, simplifying product design and accelerating the solution's market entry.

For example, built-in segmented LCD controllers and capacitive touch buttons in wireless chips reduce the complexity of LCD panel solutions. Integration of codecs and internal DACs for voice playback enhances voice prompting capabilities in devices without screens. Built-in Ethernet controllers and PHYs enable data interchange between Bluetooth gateways, USB, and Ethernet, and more. Highly integrated wireless chips bring higher added value, helping IoT products to be developed rapidly and brought to market.

In conclusion

The requirements of wireless MCUs and application endpoints are still evolving and exploring. Existing applications continue to improve, and developers of unknown applications are constantly exploring. The vast downstream application market has many applications where wireless technology can be applied and developed.

 

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