At the heart of the devices that make up the Internet of Things (IoT) are a variety of ultra low power microcontrollers (MCUs), sensor networks, systems-on-chip (SoC) and communications protocols such as ZigBee. These underlying technologies operate in a fast, noisy and growing environment, delivering remote monitoring, M2M communications, motion control and a lot more.

Within this complex environment, connected devices must feature low power consumption and do so at a low cost. Microcontrollers are running at ever-lower power consumption. They monitor and control power close to the point of load, provide effective device management and, when combined with low power design architectures and manufacturing designed to be power sensitive, the total power budget and costs are dramatically curbed. MCUs are central to the IoT, accelerating the addition of wireless networking, graphics and encryption engine functionality to such application segments as healthcare, factory automation and consumer electronics.

Until recently, the 8-bit MCU based on the 8051 core was the go-to solution. While 8-bit MCUs maintain a broad base of users, they begin to lose luster when the number of sensors and their resulting data and memory requirements push past the 8-bit threshold.  The IoT also requires a wide range of communications functions based on MCUs with inherent power efficiency, scalability, fast development time and security. In response, 32-bit MCU technology is stepping up to the plate. Within the IoT, where there are a myriad of peripherals and memory requirements, individual MCUs are increasingly finding their way into SoC implementation.

The Renesas RX64M Group

Targeting high speed and low power requirements inherent in industrial and office automation networks, the Renesas RX64M Group 32-bit MCUs operate at up to 120 MHz and use the powerful RXv2 core. This core provides for 1.6 times the performance and a 40 percent reduction in power consumption when compared to existing RX products.

As required by rapidly evolving IoT products, features of the RX64M Group include:

• The largest flash and SRAM combo in a 32-bit general purpose microcontroller, to specifically enable the IoT,
• 40 nm process technology for increased on-chip memory capacity, as well as higher CPU performance and lower power consumption,
• Extensive peripheral functions. including PWM timer functions, 1588-compliant Ethernet functions, support for high-speed communications functions and an encoding function that provides greater reliability,
• Operation at up to 120MHz and with a zero wait state.

The 112-device RX64M MCU family, running up to 120 MHz, is particularly important in environments such as smart factories and smart buildings to support factory communications from the plant to the device. The increased memory capacity continues to support further application equipment miniaturization as well as secure software, especially from third-party vendors. Low power MCUs in IoT applications must accommodate a variety of communication protocols. The connected network and industrial equipment used to enable smart factories and smart buildings drives demand for increased memory specifically to address the wide range of communication functions, which in turn plays a key role in the further miniaturization of devices. 

In order to effectively address the IoT, MCUs need to provide efficiency, security, tools, scalability and an environment that ensures reduced development periods. While managing complexity is certainly a goal, the number of process steps and costs from development through test for both software and hardware with expanding capacities and scales continues to increase, making the reduction in development time a major feat.  The MX64M MCU development environment ecosystem includes such third party OS suppliers as Micrium, Express Logic, CMX, SEGGER and FreeRTOS. In addition, Renesas’ e2 studio Integrated Development Environment (IDE)  and IAR’s Embedded Workbench for RX provide complete build and debug support.

At their fingertips, designers have a Renesas Starter Kit featuring a Renesas E1 on-chip debugger and an RX driver package provides a collection of driver software for on-chip peripherals. An interactive GUI-based code generation tool is integrated into the e2 studio IDE for automatic generation of initialization and driver code for MCU peripherals. This abundance of tools and available vendors reduces the number of development and testing process steps and, as a result, total cost.

The RX64M and other recently announced microcontrollers that target the IoT continue to provide for the diverse applications that will be connected. Continued miniaturization of MCUs will drive IoT use in such products and environments as smart home systems, wearable electronics, low-power industrial devices and ingestible devices for health application monitoring.

The challenging future for MCUs

Application software will deliver the greater intelligence required in embedded devices, providing for reliable interactions between connected devices no matter the OS used. System-level challenges for cloud-connected devices include security. The embedding of AES encryption blocks in MCUs will provide a secure, yet cost-effective solution, and can be implemented in both software and hardware.

MCUs are, and will continue, on the path to becoming even more optimized, combining a smaller footprint and extremely low-power performance. As billions of devices connect, they will do so on harvested energy or batteries that last for the lifetime of a device. To meet this growing need, MCUs are expected to increasingly expand in security, data integrity and hardware/software scalability capabilities. MCUs will also provide the massive memories needed for wireless connectivity so that devices are able to use such protocols as ZigBee that are lightweight and deliver the requisite data rates. While Wi-Fi can be used when high data rates for bandwidth-intensive tasks such as streaming video are necessary, low-bandwidth apps, 2.4 GHz ZigBee and sub-GHZ RF deliver a wireless link that is power efficient and easy to integrate into connected embedded devices.

In the future, MCUs will be supported by a greater number of tools and software, and design engineers will be able to select a MCU from a broader supply, based on performance and cost. MCUs will continue to be upwardly compatible for easier implementation and reliability and they will be secure. All of these requirements are expected to be realized soon, fueled by the burgeoning demand for even more IoT device connectivity.