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Questions tagged [rtos]

An RTOS is a Real-Time Operating System, a type of operating system that is designed to satisfy, possibly hard or firm, timing constraints. An RTOS is most likely to be used in in verifiable or safety critical systems. Such systems arise most frequently in the medical, automotive and defense industries

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What happens in the CPU when there is no user code to run?

It sounds reasonable that the os/rtos would schedule an "Idle task". In that case, wouldn't it be power consuming? (it sounds reasonable that the idle task will execute: while (true) {} )
Yony
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Which Linux RTOS solution should I choose?

I'm preparing myself to build RTOS solution on top of Linux this going to work on embedded device. I've done some investigation by myself but still I'm a bit confused. Those are my criteria: Easy to run on Samsung s3c2440 ARM9 machine Open…
Chris Ciesielski
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State machine versus RTOS for microcontrollers

I stumbled across a free state machine tool. This appears to be for programming embedded systems graphically. By doing so, the author claims that the resulting code is more maintainable than if an RTOS had been employed. This tool is based on UML,…
Otto Hunt
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Run VxWorks on VMware

I'm a newbie to VxWorks but I've worked with other RTOSes. Similar to others, can I run the VxWorks RTOS on VMware as target on my windows development host? I did not find any VxWorks iso or vmdk file anywhere, how can I get one? Can someone help…
Abhay Nayak
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Why can't FreeRTOS software timer callback use blocking API

Quoting the documentation (emphasis theirs) Timer callback functions execute in the context of the timer service task. It is therefore essential that timer callback functions never attempt to block. For example, a timer callback function must not…
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Embedded RTOS Stop System

I'm learning FreeRTOS on a Cortex M0. (Simultaneously, I'm learning the Cortex as well...). I've got plenty of experience with 8bit MCUs. I'm going through the newbie tutorials on FreeRTOS and I understand setting up basics tasks and the idle…
Leroy105
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What happens when Semaphore is released or signaled in RTOS?

Let there be 6 tasks, out of 6, 4 (task) are waiting for a Semaphore. When a semaphore is signaled, what decision is made by RTOS which tasks to pick from the waiting(for semaphore) list if one task is picked from the waiting list what will happen…
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Micrium uC-OS/II on Dynamic C/Rabbit - might have task starvation

I'm trying to get 2 tasks to run in my Dynamic C under Micrium uC-OS/II. One task is the http handler, the other reads from the serial port. The serial port task seems to inhibit the http task from running. Any ideas why this is? I thought…
fred basset
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Gang scheduling in RTOS over a multicore processor

I understand that Gang scheduling is a scheduling algorithm for parallel systems that schedules related threads or processes to run simultaneously on different processors. Gang scheduling is used so that if two or more threads or processes…
Karthik Balaguru
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How to calculate a RTOS task's time

I have written a code in c for Arm7 using RTOS. There are multiple tasks who's priority is set to same level. So the tasks executes on round-robin base. There is an exception that one task (Default) has set to lower priority then the other task in…
Adnan
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FreeRTOS Sempahore from ISR not working

I need to make a data accusition device whose one task is to samples some GPIO's and record the GPIO status and send it to PC via UART to display in PC. The algorithm i chose was (please correct me since iam very novice in RTOS) to create a timer…
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why are RTOS coded only in c?

Is it necessary to code RTOS in C language always? Why can't that be coded in java or some other technology..?? Is that because of the absence of pointer concept in java?
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How can CAS simulators like PTLsim achieve cycle accurate simulation of x86 hardware?

Can somebody enlighten me how does CAS software like http://www.ptlsim.org/ work? How do they achieve cycle accuracy if there is neither information how many cycles are used per instruction nor CPU branch prediction logic is known? Or is everything…
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Is there an RTOS for normal PCs?

Is there an RTOS that can be run on a normal PC? Where normal means something like a laptop with an intel i3 processor and 4 GB RAM. If no such system exists, is it possible to make one?
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Memory Pool vs. malloc

I was going through some Real time OS specifications and I read that In RTOS we usually don't prefer to use malloc. The reason for this was given as: for performance issue we should not use malloc as it is time consuming to allocate memory through…
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