September 30th, 2016 by
A real-time operating system refers to an operating system with guaranteed capability of meeting specific time deadlines or time constraints. For instance, an operating system that is designed to make sure that a specific object is available to a robot on the assembly line is an example of an RTOS.
Typically, a Super-Loop concept is used in simple embedded systems where each function is executed by the application in a specific order. For time-critical programs parts, Interrupt Service Routines are used. Although this is a suitable approach for some small systems, it has limitations in complex applications. This makes an RTOS a preferred operating system for such systems.
A Real-time OS separates the functions of a program into self-contained tasks while implementing an on-demand execution scheduling. There are numerous advantages or benefits of an advanced RTOS. They include the following:
- Task scheduling: This entails calling tasks when necessary to ensure better flow as well as event response.
- Multitasking: This involves task scheduling that creates the illusion that several tasks are executed simultaneously.
- Shorter ISRs: This enables a more deterministic interrupt habit or behaviour.
- Deterministic behaviour: Interrupts and ensures events are handled within a specified time.
- Inter-task communication: This manages data, hardware resources and memory sharing among several tasks.
- System management: This enables you to focus on the development of an application instead of managing resources or housekeeping.
- Stack usage: Every task has a stack space allocated to it making predictable usage of memory possible.
In general, an RTOS requires multitasking, process threads with prioritization capabilities and sufficient interrupt levels. A real-time operating system is mostly required in a small embedded system that is packaged as a micro-device part.
Among the most common designs of an RTOS are event-driven and time-sharing. Event-driven designs entail switching tasks when a higher priority event needs servicing. This is usually known as priority scheduling or pre-emptive priority. Time-sharing design entails switching tasks on a timed or clocked interrupt and also on events, known as round robin. Time sharing RTOS designs tend to switch tasks more often than is strictly needed. However, time sharing RTOS designs provide smoother multitasking. This gives the illusion that the user or process has one use for the machine. Nevertheless, a real-time operating system has numerous advantages if is used in the right manner for an application.