In this paper we point to some errors in recent paper by Asyaban et al. in which they devise an exact schedulability test. These errors are critical for the correct operation of the algorithm and they should be corrected.

The concept of weakly hard real-time systems can be used to model real-time systems that may tolerate occasional deadline misses in a bounded and predictable manner. This model applies to many practical applications and is particularly interesting in the context of real-time control systems. In practice, applying hard real-time constraints may be too rigid since a certain amount of deadline misses is acceptable in some applications. In order to maintain system stability, limitations on the amount and distribution of violated deadlines need to be imposed. These limitations can be formally expressed as weakly hard real-time constraints. Current research in the field of weakly hard real-time task scheduling is focused on designing scheduling algorithms that guarantee the fulfillment of constraints, while aiming to maximize the total number of timely completed task instances. This paper provides an extensive literature review of the work related to the weakly hard real-time system model and its link to the field of control systems design. The weakly hard real-time system model and the corresponding scheduling problem are described. Furthermore, an overview of system models derived from the generalized weakly hard real-time system model is provided, with an emphasis on models that apply to real-time control systems. The state-of-the-art algorithms for scheduling tasks with weakly hard real-time constraints are described and compared. Finally, an overview of controller design methods that rely on the weakly hard real-time model is given.

Harmonic periods have been of great importance in the design of real-time applications due to their high schedulability, predictability, and ease of analysis. Therefore, period assignment is an important part of the design process of many real-time systems. This includes various applications such as radar dwell tasks, robotics, and industrial control applications, where tasks are specified using period ranges and worst-case execution times. In this paper, we study the issue of assigning a fixed number of harmonic periods from period ranges to maximize utilization in real-time systems. In the existing period assignment approaches, the number of different harmonic period values in the solution was not addressed. In this work, we show that, in real-time systems in which the number of available task periods is restricted, such a constraint is crucial for efficient system design. We formally define the problem in the context of existing harmonic period assignment research. We show that this problem is at least weakly NP-hard and devise an optimal algorithm and suboptimal heuristics. Based on an extensive evaluation on synthetically generated task sets, we conclude that our approach is efficient and applicable in a variety of real-world scenarios.

The advent of the new Internet-of-Things (IoT) paradigm in last few years redefined the ways how the small embedded systems can enhance smart sensors and actuators to provide new possibilities in ubiquitously interconnected global world. Although there is a rising tendency in modern low-power embedded system design to provide some kind of IoT functionality out-of-the-box due to the availability of network-aware microcontrollers and system-on-chip (SoC) solutions, there is also a great need to upgrade legacy solutions to fit them into this new paradigm shift. In this article we describe a simple generic framework for upgrading legacy devices, which was built upon the state-of-the-art low cost and low power off-the-shelf hardware components, and open source software. The solution can be easily adapted for various types of smart sensors and actuators. We describe a common set of requirements for building such systems, design decisions reasoning, comparison and justification of HW/SW components choice, and sample demonstration of adaptation and upgrade of the chosen commercial equipment, a device for bubble production at children fun events and similar applications.