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[SOLVED] Basics of Real Time OS

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shaswat

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I am trying to learn the RTOS from scratch and for this, I use freeRTOS.org as a reference. I find out this site as a best resource to learn the RTOS. However, I have some doubts and I was trying to find out but not able to get exact answers. The questions are:


1) How to find out that device have Real-time capability e.g. some controller has (TI Hercules) and other don't have(MSP430)?

2) Does that depend upon the architecture of the CORE (ARM Cortex-R CPU in TI Hercules TMS570)?

3) What is meant by "OS" in RTOS? Does that mean the same OS like others or it's just contains the source code file for the API's?

Thanks in advance
 

ffllyyffllyy

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I am trying to learn the RTOS from scratch and for this, I use freeRTOS.org as a reference. I find out this site as a best resource to learn the RTOS. However, I have some doubts and I was trying to find out but not able to get exact answers. The questions are:


1) How to find out that device have Real-time capability e.g. some controller has (TI Hercules) and other don't have(MSP430)?

2) Does that depend upon the architecture of the CORE (ARM Cortex-R CPU in TI Hercules TMS570)?

3) What is meant by "OS" in RTOS? Does that mean the same OS like others or it's just contains the source code file for the API's?

Thanks in advance
1. some OS need more hardware resource ,some not.
2. becase of the differece between of ARM DSP FPGA, a certain OS may support one arch
3.operation system ,like linux and windows ,but not so much fuction
 

doraemon

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Hello!

1. First, what do you mean by "real-time".
Real time does not mean anything. In some circumstances, a 4-bit microcontroller running at 100 kHz can be
real-time and in other circumstances, a 64 bit quad core at 3 GHz might not be real-time.
In the first case, for instance, if you want to do a temperature logger for meteorological applications, that logs
the temperature once per hour and transmits it over a 9600 bps modem, then the 4 bit device is real-time
(i.e. it has more power than it needs to do what it has to do).
In the second case, if you want to predict meteorological data 5 days from the current state, then a 64 bit
quad core is not real-time (i.e. it has not enough power to do the job).

2. Real-time depends on the power you have vs what you want to do (see above)

3. OS, as replied above is an operating system. The word itself, like real-time, cannot be clearly defined.
Basically it's a piece of software providing the basic environment to make your hardware parts work
together. In an embedded system, it can be very sketchy. If you choose to use an operating system, you
have to be sure of what you do. It's not necessarily more efficient to use one. Most likely to be less
efficient. In many cases, a simple list of task in a loop (round robin) can make the job very efficiently,
without having to manage the CPU registers.

Dora.
 

guttinasrinivas

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The fundamental principle of RTOS: If a job is not done in a define time, the job is failed.

A RTOS guarantees a response (whether successful or failure handled) as a function of time interval. A GPOS on the other hand, does not have any defined time guarantees. For example, a file read from a disk on Windows or Linux may take very long time if the disk is not healthy. The reading process in this case would wait till either the disk and drivers give up or manage to retrieve data. In a RTOS, if the data is not read within given time limit (e.g. 10 second), the job is considered failed. So, the process starts executing failure handling code.

To accomplish these goals, a RTOS depends heavily on a few basic constructs: low latency interrupt handling, precision timers and properly designed priorities and interrupts.

I written some articles on my blog: https://guttinasrinivas.wordpress.com/category/technology/rtos/
 

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