Real-Time Operating Systems: FreeRTOS vs VxWorks Insights

CPR E 558 HW1 Submitted by: (Section 1) Hounandan Ravichandran - nandan35@iastate.edu Mani Kanta Lokesh Buragadda - bmlokesh@iastate.edu Question A: 1) Two Real-Time Operating System a) Two popular Real time Operating Systems(RTOS): i) FreeRTOS ii) VxWorks iii) Both these RTOS are used for various applications which require deterministic predictable behavior in terms of response time and task scheduling. (1) Some of the Real-time applications: (2) Embedded systems (3) IOT Devices (4) Aerospace (5) Military Defense (6) Consumer electronics (7) Medical Devices (8) Networking iv) Scheduling Algorithms used in VxWorks: It supports two scheduling algorithms a basic pre-emptive priority one and a round-robin algorithm. v) By default, FreeRTOS uses a “Fixed-priority” preemptive scheduling policy, with round-robin time slicing of equal priority task. Fixed-priority means the scheduler will not permanently change the priority of a task, boosts the priority of a task temporarily due to priority Inheritance. Preemptive scheduler runs the highest priority a RTOS tasks, regardless of when a task is ready to execute. Robin hood: each tasks of same priority takes turns entering the running state. FreeRTOS Scheduling algorithm has three configurations Single core (Default)- fixed-priority preemptive scheduling Asymmetric multicore (AMP)- each core has its own single core scheduling algorithm.

Symmetric multicore (SMP) -scheduling policy uses the same algorithm as the single-core scheduling policy but, unlike the single-core and AMP scenarios, SMP results in more than one task being in the Running state at any given time. 2) Real world application: Static real-time system with hard deadlines: Example: Missile Defense a) Justification: An air-defense system that is monitoring the sky for an incoming enemy missile. Due to the nature of the application the timing constraints and this imposes several deadlines on other tasks like detecting, identifying, engage, or launching an intercept missile to tackle. b) Immediate Threat Response: Incoming missiles can travel at incredibly high speeds, leaving only seconds to react. c) Precision and Accuracy: Missile defense systems rely on sophisticated sensors, radar, and tracking systems to detect and intercept incoming threats accurately. d) National Security: The stakes in missile defense are exceptionally high, as the protection of a nation's citizens and infrastructure depends on timely responses. e) Reliability: Static real-time systems are designed with predictability and reliability in mind. f) Continuous Monitoring: These systems continuously monitor airspace for potential threats, and hard deadlines ensure that the system remains vigilant around the clock, ready to respond instantly when necessary. Dynamic Real-time System with Both Periodic and Aperiodic Tasks with Hard Deadlines. Example: Airplane Sensor and Autopilot Systems. g) Safety-Critical Operations: Navigation, collision avoidance, and stability control are among the crucial tasks that airplane sensor and autopilot systems are in charge of. Setting strict timelines is essential to ensuring that these systems react quickly and correctly to changing circumstances, guaranteeing passenger safety. h) Periodic Tasks: In aviation, periodic tasks involve gathering sensor data at predetermined intervals, such as altitude, airspeed, and attitude. To ensure that these data points are gathered and processed consistently and to enable precise flight control and monitoring, strict deadlines are established. i) Aperiodic jobs: Aperiodic jobs, such as reacting to abrupt changes in weather or air traffic, need for rapid attention. Hard deadlines guarantee that the autopilot and control systems can quickly respond to unforeseen circumstances, assisting the aircraft in navigating turbulence, avoiding crashes, or handling crises.

j) Predictability: In aviation, predictability and reliability are paramount. Dynamic real-time systems with hard deadlines provide a clear framework for task scheduling, minimizing the risk of task overruns or delays that could compromise flight safety. k) Redundancy and Fail-Safe Mechanisms: These systems often incorporate redundancy and fail-safe mechanisms to ensure reliability. Hard deadlines help maintain the integrity of these mechanisms, ensuring that backup systems are activated promptly when needed. Dynamic real-time system with soft deadlines. Example: Smart Home Automation. l) By giving consumers control over different elements of their home environment, including lighting, temperature, and appliances, smart home automation systems are intended to improve convenience, energy efficiency, and security within a family. m) User Convenience: Simplifying and improving everyday life is the main objective of smart home automation. When they offer requests, like turning on the lights or regulating the temperature, users anticipate prompt replies. The occasional delay in command execution won't have a significant impact on these systems though. n) Robustness: Redundancy and fail-safes are frequently used in the design of smart home systems. of the event of a delay or interruption of one component or communication channel, the system can continue operate utilizing alternate channels. o) Security: A key component of smart home automation is home security systems. The overall state of security is often not compromised by tiny delays in getting notifications or activating security measures, even if real-time monitoring and quick response to security events are essential. Question B: 1)Precedence Task Relationship: A. Two tasks (one for each camera) dedicated to image acquisition, whose objective is to transfer the image from the camera to the processor memory,they are identified by acq1 and acq2 ; B. Two tasks (one for each camera) dedicated to low-level image processing, typical operations performed at this level include digital filtering for noise reduction and edge detection; we identify these tasks as edge1 and edge2 . C. A task for extracting two-dimensional features from the object contours,it is referred as shape . D. A task for computing the pixel disparities from the two images,it isreferred as disp .

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