The article presents performance tests of code executed by STM32 microcontrollers using a virtual machine (so-called intermediate code) dedicated to control systems. The ARM architecture used in these chips has limitations related to access to non-aligned addresses. Three ways to overcome these limitations have been proposed, and each has been subjected to a suite of tests to determine their performance. Tests were conducted for two operating modes, i.e. with 16- and 32-bit addressing for different generations of chips. The test results allow to choose the right solution for a specific platform.

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This work aims to investigate the impact of memory access limitations in microcontrollers and microprocessors on the performance of software that deals with binary data. The research area covers control systems that process data from the IEC 61131-3 standard using a software-implemented virtual machine. Three methods of memory access are considered, namely byte access, memory copying, and direct pointer. Tests of these methods are performed on several CPUs with ARM architecture (with variants), MIPS, RISC-V, Quark, and others, often used as hardware platforms for control devices. The tests cover 1-, 2-, 4-, and 8-byte data sizes, which correspond to the integer types of the IEC 61131-3 standard. By analyzing the results covering both unaligned and aligned data, the goal of this paper is to indicate which of the memory access methods is the most efficient for a particular platform. The research is supplemented with an evaluation of power and memory requirements for a group of STM32 microcontrollers. Therefore, the contribution of this paper rests in indicating the most efficient memory access method for each of more than a dozen CPUs intended for control applications, with consideration of power and memory requirements.

The paper discusses the issue of EMC compatibility of autonomous navigation robots that utilize the RFID technology for surface discovery. The robots can work individually or in a group in environments equipped with RFID transponders. The need to examine EMC compatibility of such robots is pointed out, so that they can work and communicate without disturbing other devices or each other. Measurements and analysis of electromagnetic disturbances generated by a prototype of a navigation mobile robot has been carried out. Results of the measurements for the model of the robot are presented. Factors determining generation of the disturbances in the model are pointed out.