21-11-2012, 06:18 PM
An Introduction to RTOS
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INTRODUCTION
RTOS is a multitasking operating system intended
for real-time application. Such applications include
Embedded system (programmable thermostats,
household appliance controllers)
Industrial robots, spacecraft, industrial control
(SCADA)
Scientific research equipment etc.
A RTOS facilitates the creation of a real time
system, but does not guarantee the final result will be
real-time, this requires correct development of the
software. An RTOS does not necessarily have high
throughput, rather an RTOS provides facilities which, if
use properly, guarantee deadline can be met generally or
deterministically (know as soft or hard real-time,
respectively). An RTOS will tropically use specialized
scheduling algorithms in order to provide the real-time
developer with the tools necessary to produce
deterministic behavior in the final system. An RTOS is
valued more for how quickly and/ or predictably it can
respond to particular event then for the amount of work
it can perform over a given period of time. Key factors
in an RTOS are therefore minimal interrupt latency and
minimal thread switching latency.
RTOS ARCHITECTURE
The heart of any RTOS is the kernel. Inside the
kernel is the scheduler. It is basically a set of algorithms
which manage the task running order. Multitasking
definition comes from the ability of the kernel to control
multiple tasks that must run within time deadlines.
Multitasking may give the sensation that multiple
threads are running concurrently, as a matter of fact the
processer runs task by task, following scheduled other.
INTERTASK COMMUNICATION AND RESOURCES SHARING
Multitasking systems must manage sharing data and
hardware resources among multiple tasks. It is usually
“unsafe” for two tasks to access the same specific data
or hardware resource simultaneously. (“Unsafe” means
the results are inconsistent or unpredictable, particularly
when one task is in the midst of changing a data
collection. The views by another task are best done
either before any change beings, or after changes are
completely finished.) There are three common
approaches to resolves this problem:
CONCLUSION
It is said that the combination of hardware design
along with the software embedded into memory is said
to be known as the embedded system design. Embedded
system design is related to RTOS in the sense that it take
control of all interrupts that would be handled at time of
execution of the task thus the user to free to do another
jobs simultaneously.
Another advantage with the RTOS and the hardware is
that it is replacing the ASIC based design because the
cost of the ASIC is very high and its hardware cannot be
ultered, on the other hand the embedded system design
when added with RTOS gives us the concept of
reconfigurable computing.