While the author is writing this article, the number of IoT devices worldwide continues to increase. In recent years, IoT was even integrated into the industrial control field and artificial intelligence-related applications, resulting in IIoT and AIoT. These applications were built on the collection, computation, processing, transmission, and storage of data. With the emerging need to connect everything, “information security” became inseparable with IoT devices. After Nuvoton experienced the development and market feedback of the first generation IoT security microcontroller M2351, it gained experience. Therefore, it launched its next-generation product at the beginning of the year – the M2354 series. The entire M2354 IoT secure microcontroller series are equipped with 1M Bytes of dual-block flash memory; not only do they have sufficient memory space to complete OTA updates, but the dual-block design also allows IoT devices to continue using their original old firmware versions when the updating of the new firmware failed. In addition, M2354 also enhanced the physical security of the hardware password accelerator and key store, allowing IoT devices to be faster and more secure while working over the cloud. The following are the descriptions of the main function block of a universal secure IoT terminal device application evaluation board developed based on Nuvoton’s M2354 series chip:

Based on M2354’s main secure networking feature, Nuvoton designed the NuMaker-IoT-M2354 evaluation board; it is equipped with a Wi-Fi module (ESP-12F) and environmental sensor (BME680), able to measure surrounding temperature, humidity, IAQ, and other values, and the data can be sent to the cloud using the cloud connection paradigm in the Mbed OS software organized by Nuvoton; users can also obtain related data on their mobile phones through the monitoring APP developed by Nuvoton. The data access and uploading mentioned above can have their transmission interface configured to the “Secure” attribute. Only when the microcontroller is in the corresponding secure status or through the reference of legal API can the message be obtained successfully.

In addition, the AES hardware algorithm function of M2354 was also enhanced, and it now supports GCM, CCM, and SM4 models. The GCM model is based on the CTR model with the addition of GMAC (Galois Message Authentication Code) computation, able to provide encryption and integrity checks for messages; CCM is the integration of CTR and CMAC algorithms, and currently, the TLS 1.2/1.3 versions also use AES-GCM to perform symmetric encryption and decryption processing. SM4 also uses symmetric encryption standards, which China’s State Cryptography Administration proposed in 2012; its key and packet length is 128 bits, and the security is equivalent to AES-128. The complete hardware encryption and decryption resource provided by Nuvoton allows encryption to be completed for your important data before transmission. The related key is also stored in the key store in advance. Also, for the side-channel attacks often used for key cracking, corresponding protection measures are provided on the M2354 chip, enabling the protection setting while enabling the encryption function to improve the protection of the message and the key significantly.

Besides the Wi-Fi function, the NuMaker-IoT-M2354 evaluation board is also equipped with the REYAX LoRa module; the Maker can select RYLR890 or RYLR400 for system development based on the requirement of the frequency band used and as the LoRa terminal device. Moreover, when used with the NUC980 LoRa Gateway (ARM9 series) solution launched by Nuvoton, it can easily connect to the cloud! Refer to the following table for detailed connection methods for IoT-M2354.

Finally, the evaluation board is also equipped with the standard mikroBUS interface; the Maker can select suitable expansion boards according to the uses and develop various types of applications.

For IoT devices equipped with display functions (e.g., Smart Meter), the NuMaker-IoT-M2354 evaluation board also provides an additional eight com/40 seg HTN-LCD; users can get familiar with the operation of M2354’s LCD driver through this screen first and then design suitable screens to use with the actual products! NuMaker-IoT-M2354 will be sold on Nuvoton Direct; interested readers can keep an eye out! The following is the list of software functions provided by Nuvoton based on this evaluation board that allows developers to get started quickly:

NuMaker-IoT-M2354 Quick start

User Manual
 Schematic, PCB & Gerber File