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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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FreeRTOS: Why to call taskYIELD_FROM_ISR() method within the isrHandler

I try to understand why the user has to call the taskYIELD_FROM_ISR() method and why it isn't automatically called by the RTOS within the xStreamBufferSendFromISR method. My question refers to the FreeRTOS_Manual p. 369. /* A stream buffer that has…
PascalS
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Why do RTOS tasks have to be executed in infinite loop?

Hi I'm a newbie in RTOS and in almost every document I read, it indicates that the tasks must be in infinite loop but none states why. Can anyone help explain this? Thanks
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Ada multitasking RTOS supported with opensource cross-compilers

Which RTOSes do Ada have opensource/free cross-compilers available, with support for multitasking/multithreading? I have an Atmel AT90USB162 chip which I want to program using Ada. My first option was to use AVR-Ada for programming it, but since it…
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Real Time Operating Systems for Embedded Systems -> Good Starting books

I have worked extensively on AVR microcontrollers. I haven't had a proper OS course at UNI..not from a CS branch, but I want a book that gives me generic OS concepts as well as RTOS concepts for embedded systems. Any suggestion?. Something that…
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Achieving realtime 1 millisecond accurate events without suffering from thread scheduling

Problem I am creating a Windows 7 based C# WPF application using .Net 4.5, and one its major features is to call certain functions that interface with custom hardware with a set of user defined cycle times. For example the user might choose two…
Ahmed Agamy
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Prototyping and simulating embedded software on Windows

I am looking for tools and techniques for prototyping (virtual prototyping), simulation, and testing of deeply embedded C code on desktop Windows, including building realistic embedded front panels consisting of buttons, LEDs, and LCD displays (both…
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What is the right RTOS for a humanoid robot?

We're students developing a mid-size (~ 4.5 feet tall) humanoid robot as a sponsored research project in college. The major tasks that the robot should be able to perform include: moving around (forward, backward, sideways), running, picking up…
Vicky Chijwani
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Unit Testing a project that uses an RTOS

For my next embedded systems project I want to embrace unit testing. It may not technically be test driven development, but I would at least like to instrument unit tests up front and have comprehensive unit testing. I am using the IAR EWARM tool…
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How RTOS does task switching from interrupt

Suppose there is two task running TASK_A and TASK_B. While TASK_A is running an interrupt occurred and a context switch to TASK_B is needed. While inside ISR, TASK_B should not be directly jumped since it is still in ISR and have'nt returned yet…
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Soft Real Time Linux Scheduling

I have a project with some soft real-time requirements. I have two processes (programs that I've written) that do some data acquisition. In either case, I need to continuously read in data that's coming in and process it. The first program is…
It'sPete
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Why is disabling interrupts necessary here?

static void RadioReleaseSPI(void) { __disable_interrupt(); spiTxRxByteCount &= ~0x0100; __enable_interrupt(); } I understand that multiple tasks may attempt to use the SPI resource. spiTxRxByteCount is a global variable used to keep…
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difference between Preemption and context switch

A little intro, I am currently writing a small (read tiny) RTOS kernel, well it's supposed to be monolithic with most stuff in the kernel. However I can't find much information on a few things listed below, It would be a lot helpful and besides…
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Does it make sense to mix an RTOS and cyclic executive?

On a small embedded system project we have some code which we would like to run in a thread so we are electing to build in top of an embedded RTOS (eCos). Previously, we have used a cyclic executive in main() that drove tasks each implemented as a…
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How are the vxWorks "kernel shell" and "host shell" different?

In the vxWorks RTOS, there is a shell that allows you to issue command to your embedded system. The documentation refers to kernel shell, host shell and target shell. What is the difference between the three?
Benoit
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Difference between OS scheduling and RTOS scheduling

Consider the function/process, void task_fun(void) { while(1) } If this process were to run on a normal PC OS, it would happily run forever. But on a mobile phone, it would surely crash the entire phone in a matter of minutes as the HW watchdog…
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