STMicroelectronics Offers Energy-Efficient MCUs for IoT Application Development
High security performance and fast, economical prototype development possible

Smart healthcare, home IoT, industrial IoT, and the Internet of Small Things are key areas in the industry outlook for next year that has been pouring out recently.

In other words, the Internet of Things (IoT) is now beginning to blossom into a tangible business in specific fields. Accordingly, the semiconductor industry is racing to release specialized solutions to implement these IoT applications. MCUs, which play a key role in configuring intelligent systems, are no exception.

In particular, the key requirements for MCUs implementing IoT applications are low power, communication, and security. STMicroelectronics' latest STM32, which already boasts a wide user base, is considered a representative solution that satisfies these requirements.

“ST MCUs are specialized for IoT application development in three key areas,” said Kim Du-hyung, Manager at STMicroelectronics Korea. “First, they are highly energy efficient. Many IoT application products these days are battery-powered. These products are sensitive to energy efficiency, making low power consumption paramount. ST MCUs offer exceptional energy efficiency through various low-power modes and technologies, giving them a competitive edge in the IoT market.”

The second reason given by Manager Kim is its high security performance. STMCU provides high-level security algorithms as a hardware unit, so it is explained that various security functions such as Firewall, Read/Write protection, Anti-Tamper, and Crypto can be easily applied just by using this one chip.

Finally, he cited rapid and economical prototyping. ST distributes Nucleo boards with Arduino support, STM32CubeMX software, and software libraries. Among these, STM32CubeMX and software libraries can be downloaded free of charge. It also provides X-Nucleo, which supports various functions such as BLE, LoRa, Wi-Fi, sensors, and Sub-GHz RF.

The idea is that you can easily combine it with the Nucleo board like stacking Lego blocks to quickly implement desired functions. ST's support for an open development environment has been a key selling point for engineers, as it significantly reduces the time and cost of prototyping.

So, I decided to go into more detail, one by one. Below is a Q&A with Manager Kim.

Issue 1. Low-power perspective

Q. Among the STM32 product line, the STM32L series is said to be an MCU specialized in low power, but other companies are also releasing many low-power MCU products. Please explain how it is different.
A. First, it has the best energy efficiency. According to the results of the EEMBC ULPBench, a standard benchmark test comparing the efficiency of low-power microcontrollers announced in February of this year, the STM32L series achieved 176.70 ULPMark-CP without a buck converter that requires external components such as coils or capacitors, surpassing the scores of competing products. It also achieved an EEMBC CoreMark score of 273.55 at 80MHz, objectively proving its industry-leading performance and power efficiency. Furthermore, the ability to utilize a variety of detailed low-power modes allows for a variety of low-power applications depending on user application scenarios. In particular, STMCUs are highly resilient to external environmental characteristics compared to competing MCUs due to their low current consumption variation with temperature changes.

Q. While the MCU's low-power performance is important, its relationship with the surrounding circuitry is also crucial. Are there any devices or features that minimize power consumption in each mode?
A. First, you can utilize Batch Acquisition Mode (BAM), which optimizes data transfer with optimal current consumption by combining the communication interface and internal SRAM while in low-power mode (Sleep mode). Additionally, there are low-power Timers and low-power UARTs that operate with minimal current consumption in low-power mode. Furthermore, the STM32L4 supports independent power inputs for I/O, USB, LCD, and analog, enabling hardware-level power savings.

Q. For example, in the STM32CubeMX current consumption simulation, what functions and scenarios can developers include to estimate the results?
A. STM32CubeMX's current consumption simulation function can calculate current consumption estimates based on the user application's approximate operating conditions and low-power mode scenarios. Depending on the application, battery usage and type can be selected. Furthermore, the operating time and activated peripherals for each low-power mode can be selected and added to configure a comprehensive scenario, allowing the current consumption estimates to be verified.

Issue 2. Communication Perspective

Q. Communication is crucial for IoT configuration. What communication modules are supported, and how can developers easily add new ones to the board they want to use?
A. ST offers a variety of X-Nucleo boards that are compatible with Nucleo boards, including BLE, LoRa, Sub-GHz RF, and Wi-Fi. These enable rapid and economical prototyping.

Issue 3. Security Perspective

Q. What security features does STM32 provide in addition to those built into the ARM core, and what are the reasons for them?
A. STM32 provides a variety of high-level security functions as a hardware unit. Specifically, first, there is a Firewall to protect data or code in a specific part of Flash or SRAM from codes running outside the designated area, second, an Anti-Tamper function to protect against physical access from outside the MCU, and third, a CRC calculation unit used to verify transmitted data. 4) Security algorithms such as Random Number Generator, Hash, Cryptographic, and AES have dedicated hardware devices built in to enable high-speed processing.

Issue 4. Development Environment Perspective

Q. What are the differences between your company and other companies in terms of development environment support, such as tools and software?
A. First, ST-Link/V2 is a low-cost program and debug tool that supports SWIM and JTAG/SWD and can be used for STM8 and STM32 development. In terms of hardware tools, it provides various reference boards, such as Nucleo boards that include Arduino and ST Morpho headers and support the mbed environment, Discovery boards that can test specific functions of the MCU, and Evaluation boards that can test all functions of the MCU. In particular, the Nucleo board allows for quick and easy prototyping in conjunction with Arduino shields or the XNUCLEO board provided by ST.
The STM32Cube MX tool in the software toolbox is a tool that can generate initialization C code. It graphically sets pin outs, peripheral parameters, clock trees, etc. and generates initialization C code based on user settings. For reference, STM32Cube MX supports all ST MCU product lines.

Q. You said that the KEIL license can be used for free when using the F0, L0 family and the Cortex-M0, M0+ family. What is the benefit of this?
A. In fact, developing a project using an MCU consumes a significant amount of money, time, and effort. This also applies to building an integrated development environment (IDE). For the STM32F0 and STM32L0, a well-known commercial compiler, such as KEIL, is provided free of charge. This saves both time and money, significantly reducing the burden on project progress.

Q. Can developers obtain references in advance in various modes such as Stop mode, Sleep mode, Shutdown mode, and Standby mode?
A. Of course. You can download the Cube library for the corresponding product family from the ST website (www.st.com/stm32) and refer to example code for each low-power mode, depending on the reference board. Additionally, you can download the STM32Cube MX library to view example code for low-power modes for various reference boards in different product families.