Architecture of rtos pdf

Example: Online Transaction system and Livestock price quotation System. Skip to content. Report a Bug. Previous Prev.

Next Continue. Home Testing Expand child menu Expand. SAP Expand child menu Expand. Web Expand child menu Expand. Must Learn Expand child menu Expand. Soft Real Time Operating System In this type of Operating System , the response time of the system is prime but not critical to the operation of the system. For a Real Time OS to be functional, following parameters are to be considered: Performance : Performance is the most important factor required to be considered while selecting for an RTOS. Middleware Support : Middleware support helps Real Time Operating Systems to reduce the time-taken integration of the process.

Task Scheduling It records the state of each task and determines the task of highest priority, to be executed. Task Synchronization It is necessary for the information to be transmitted safely from one Task or Thread to another Task. Memory management It allocates the memory for each program. They are: Stack Management Heap Management Time Management To schedule the tasks that need to be executed during specified duration, there is need for a periodical interrupt. Some of the major applications are listed below: Mobile applications.

Online transaction system. Medical Critical Care systems. Aircraft and defense systems. Price quotation systems. Network and multimedia systems. Anti-Lock brake systems. Air traffic control systems. Online calling. Ticket reservation systems. Command control systems. This helps designers or testers to work independently on their parts of the project. It reduces the interdependencies between the modules by abstracting timing dependencies and task-based design.

It offers cleaners and smaller application courses. Priority-based scheduling allows the user to separate analytical processing time and Critical processing time. It requires plenty of resources, making it more expensive. It uses a complex algorithm, which makes it very difficult to interpret. It concentrates only on the accuracy of the program under execution, which increases the waiting time of low priority programs.

RTOS carries out only the minimum switching of tasks. RTOS can only run minimal tasks together. It uses plenty of resources, which sometimes are not suitable for the system. It concentrates only on applications containing an error. Chakrasthitha Chakrasthitha is a B.

During the execution of an application program, individual tasks are continuously changing from one state to another. However, only one task is in the running mode i. In the process where CPU control is change from one task to another, context of the to-be-suspended task will be saved while context of the to-be-executed task will be retrieved, the process referred to as context switching.

A task object is defined by the following set of components:. C Synchronisation and communication. Task A needs a result from task B, so task A can only run till task B produces it. Task synchronization is achieved using two types of mechanisms:. Event objects are used when task synchronization is required without resource sharing. They allow one or more tasks to keep waiting for a specified event to occur.

Event object can exist either in triggered or non-triggered state. Triggered state indicates resumption of the task. A semaphore has an associated resource count and a wait queue. The resource count indicates availability of resource. The wait queue manages the tasks waiting for resources from the semaphore.

A semaphore functions like a key that define whether a task has the access to the resource. A task gets an access to the resource when it acquires the semaphore. There are three types of semaphore:.

Semaphore functionality Mutex represented pictorially in the following figure. Intertask communication involves sharing of data among tasks through sharing of memory space, transmission of data, etc. Intertask communications is executed using following mechanisms. Usually, a message queue comprises of an associated queue control block QCB , name, unique ID, memory buffers, queue length, maximum message length and one or more task waiting lists.

A message queue with a length of 1 is commonly known as a mailbox. A pipe does not store multiple messages but stream of bytes. Also, data flow from a pipe cannot be prioritized. D Memory Management. Stack management is used during context switching for TCBs. Memory other than memory used for program code, program data and system stack is called heap memory and it is used for dynamic allocation of data space for tasks.

Management of this memory is called heap management. E Timer Management. Tasks need to be performed after scheduled durations. To keep track of the delays, timers- relative and absolute- are provided in RTOS. F Interrupt and event handling. RTOS provides various functions for interrupt and event handling, viz. It also restricts interrupts from occurring when modifying a data structure, minimise interrupt latencies due to disabling of interrupts when RTOS is performing critical operations, minimises interrupt response times.

There are number of commercially available RTOS, each with some distinct features and targeted for a specific set of applications.