Everything You Wanted to Know About RTOS

December 21st, 2016 by

An RTOS refers to Real-Time Operating System. It is a computing environment that responds to rapid inputs in a given period. In some cases, there is a small real-time deadline such that the reaction of the system seems instantaneous. However, real-time computing is also a term that is used in describing slow real-time output with a fixed, longer time limit.

Real-time operating system is extremely important in most embedded systems. It provides a platform where real-time processing applications can be built. However, an RTOS is not used to build embedded systems. Embedded systems may not require an RTOS if their hardware or code is relatively small or simple. An RTOS is mostly used with embedded systems that have a moderate or large software application that needs real-time scheduling.

RTOS Classification

A real-time operating system specifies the maximum time that is known / needed for every operation that is performed. On the basis of tolerance degree, this real-time operating system is classified into 3 categories.

  • Hard real-time: This is an operating system in which there is a negligible degree of tolerance. The system can experience a catastrophic failure in case of a missed deadline.
  • Firm real-time: In this method, a missed deadline can cause an unacceptable reduction of quality. However, it may not cause a complete failure of the system.
  • Soft real-time: With this system, there can be occasionally missed deadlines. However, the system will not fail, and system quality will be acceptable.

Sample Applications

In the case of devices that are used to save lives, think of an automatic device for opening a parachute for skydivers, where any delay can have fatal effects. This is because the opening device for a parachute is opened at a certain altitude on the basis of various conditions. In case of a failure to respond at a particular time, the parachute will not be deployed and this could lead to a fatal casualty. A similar situation might be during air bag inflation for cars during an accident. If an airbag is not inflated at the right time, the results can be fatal for the driver. Therefore, such a system has to be a hard real-time system. On the other hand, a delay in something like a live TV broadcast is acceptable. Therefore, a soft real-time system is applicable for a live TV broadcast.

Basically, an RTOS is source code or program that was designed for CPU usability management for microcontrollers. It helps in enhancing the CPU efficiency in the management of processes or tasks.


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