IoT Devices

To ensure that IoT data is also “trustable content on future blockchains”, we are developing the Metroracle solution. To enable IoT device manufacturers and IoT device owners user-friendly access to the Metroracle eco-system, the Metroracle team is developing an open-source library (IoT Metroracle library). The IoT Metroracle library aims for compatibility with the majority of the IoT devices on the market.

IoT devices come in various shapes and sizes, with different features, and the IoT market covers a wide variety of applications and use cases. Accordingly, IoT devices cover a wide range of specifications. For our use case within Metroracle project, we looked into the available IoT devices suitable for IoT usage. The following requirements are necessary for IoT devices within the Metroracle eco-system:

Software requirements:

Programming language: C/C++

OS (if applicable): Linux-based, RTOS

Hardware requirements:


ADC (Analog-Digital Converter)

UART (Universal Asynchronous Receiver-Transmitter)

I2C (Inter-Integrated Circuit Protocol)

SPI (Serial Peripheral Interface)

One additional important requirement for the IoT device is to use a secure microcontroller or equivalent device (i.e. dedicated secure chip) to store cryptographic keys. If applicable, this secure element should be compatible with EC SECP 256K1. For the secure element, which is an antitampering feature of the device, the relevant standards are: ISO/IEC 11889, ISO/IEC 19790, ISO/IEC 29192.

To provide reliability in measured data, trust and security aspects of IoT devices need to be addressed [1]. The security aspects should cover a wide range of security considerations, such as security by design, data protection and risk analysis. Necessary technical measures for preservation and protection of the IoT device and information (data) security should address: Hardware security; Trust and Integrity Management; Security, privacy, system safety and reliability; Authentication and Authorisation; Access Control – Physical and environmental security; Cryptography.

Of course, protection of IoT software, its components and measurement data should not be neglected and it should be secured against unauthorized modification. Protection from unintentional and accidental interventions for the IoT software is crucial also from a metrological point of view [2]. To be compatible with the metrology standards, IoT devices and, more specifically software/firmware of the IoT device should comply with the document of the International Organization of Legal Metrology (OIML)[3], as well as the documents and recommendations of the regional metrological organizations. In particular: software testing procedures are governed by guidelines of the European Cooperation in Legal Metrology (WELMEC)[4].

[1] “Baseline Security Recommendations for IoT in the context of Critical Information Infrastructures”, ENISA (The European Union Agency for Network and Information Security) (

[2] Oleh Velychko, Valentyn Gaman, Tetyana Gordiyenko, & Oleh Hrabovskyi. (2019). Testing of Measurement Instrument Software with the Purpose of Conformity Assessment. Eastern-European Journal of Enterprise Technologies, 1(9 (97)), 16–26.

[3] OIML D 31:2019. General Requirements for Software Controlled Measuring Instruments. OIML. Paris, 2019.

[4] WELMEC 7.2. Software Guide (Measuring Instruments Directive 2014/32/EC). URL: