A Real Time Operating System - one used typically in industrial control systems. characterized by a predicable response time to interrupts and system requests. Designed in such a way that the developer can be sure of meeting timing requirements of industrial processes.

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What is capacity in the context of scheduling algorithms in Real Time Systems?

In Real Time Systems, scheduling algorithms often speak about Capacity of a Task. For example: In ...
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RTOS: Why Do We Need Special Post versions for ISRs?

In some RT kernels, if you want to post to a semaphore or flag from an ISR, you need to call an special version of the method, instead of the regular one called from a normal task. Examples: ...
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Context switching and systick handling on the STM32F series

I am using a STM32F407 board to build my own tiny RTOS and I have some questions. How can I define my own stack in different memory location, so I can have one stack for each queue of tasks? How do ...
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scheduler and stack

i develop my own scheduler on stm32f407 board i have different queues of tasks with different priorities and frequencies i want to mange stack operations myself when in SysTick_Handler event each ...
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RTOS for Cortex M4 with 802.15.4/6LoWPAN stack

I'm evaluating operating systems to use in an Internet of Things Project and I don't know what's the best way to proceed. I'm using a TM4C123GH6PM MCU with 32k RAM and a CC2520 802.15.4 transceiver, ...
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Real time tasks with CooOs

i am using CooOs with 4 tasks.the problem is that only the first task run (indefinetly).What i want to do is to toggle each task 3 seconds then switch to the other.I know that i can do that with ...
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Why can't we have counting mutexes?

I understand the difference between a semaphore and a mutex (I think). Only the task that acquired the mutex can release it. What if we had three identical ports that are shared amongst tasks and ...
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What is the difference between context switching and interrupt handling?

I'm an embedded developer. I haven't worked with RTOS/linux. I was going through RTOS concepts when I stumbled upon 'context switching'. I understand that when context switch occurs, all the registers ...
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58 views

Correct use of TOS registry in PIC18f4550 HI-TECH C compiler

I'm working in a multitasking program PIC18f4550 HI-TECH C compiler in MPLAB X IDE. The logic of the program is: The PIC receive a command via RS232 to Load or Unload a Task. While there is ...
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Are there platforms where disabling/restoring interrupts from ISR should be done differently than from non-ISR context?

I'm familiar with several real-time kernels: AVIX, FreeRTOS, TNKernel, and in all of them we have 2 versions of nearly all functions: one for calling from task, and second one for calling from ISR. ...
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Do I need OS for ARM Cortex-M0(3)?

I'm a developer of control devices for switch mode power supplies which need to generate a PWM signal(s) with a frequencies about 100 kHz, measure analog signals, communicate vie USART, make ...
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Testing strategies for testing a Scheduler

We have developed an in-house Scheduler which is based on Rate-monotonic scheduling. We have 6 tasks (5 actual tasks and 1 idle task). Our scheduler works on 1msec timer interrupt. Before sending it ...
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180 views

Using RTOS support in OpenOCD

I can see that OpenOCD is RTOS aware and it supports FreeRTOS, which I'm using at the moment. I have looked at various sources and cannot seem to figure how to use this feature.
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Idle state in RTOS, sleep state or lowest frequency?

In real time systems using an RTOS, what how would the RTOS handle an idle period? Would it run nop instructions at the lowest frequency supported by a Dynamic Voltage Scaling capable processor? or ...
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116 views

What must be done, a new design?

I tried to compile a TCP / IP project for the MicroC / OS II RTOS with an Altera DE2 and a .sof design. I can run the MicroC / OS II with other apps but when trying ...
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What can I do to decrease the latency from these serial ports which are attached to a PC via a Serial to USB adapter?

I think I have accidentally discovered a need in my life for embedded systems. Which is great! And kind of scary. And I need help. Background: I got hired to build a GUI application which takes scans ...
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Should “get new sensor data” be its own task in an RTOS?

I am new to RTOS coding practices/architectures, and am specifically learning on RTX. Should I have a get_new_sensor_data task for each sensor, or is sensor data usually taken care of by some other ...
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164 views

RTOS with POSIX standards for dsPIC

I'm open to learning new RTOS that are free or low-cost but before I do that I want to see if there exists one with POSIX standards (threads, semaphores, mqueues). I did notice that in another thread ...
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Do I need a RTOS?

My hardware would have a DSP with the following characteristics: Sound generation (internal parameter will generate pure tones, white noise, filtered white noise or the sum of them). I2C ...
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1k views

Is there any Real time clock (RTC) which provides time resolution in microseconds?

I've been searching for high precision RTCs on Google but almost all RTCs like DS12C887, DS1307 provide time resolution in seconds which is ok for general use. But is there any RTC IC which can ...
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What features distinguishes real-time from other types of os?

I'm experimenting with a small so-called real-time kernel that basically can do nothing but counting to the next prime. It uses interrupt-driven I/O. But why is it a real-time kernel? I read that ...
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How does an embedded application and RTOS communicate with each other?

I am working on a project which uses ARM 7 processor and a micrium - os II RTOS. Kindly help me out in understanding the fundamental questions that have come to me regarding this project. Below are ...
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What development boards have good RTOS support?

I'm looking for a relatively low-cost (<$50 would be ideal) development board with real support for an RTOS. It doesn't matter if the RTOS is manufacturer-supported or a separate project, but I'd ...
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What is the reason my PIC16 multitasking RTOS kernel doesn't work?

I am trying to create a semi-pre-emptive (co-operative) RTOS for PIC x16 microcontrollers. In my previous question, I've learnt that accessing hardware stack pointer is not possible in these cores. I ...
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How to implement simple stack switching in PIC12/16 cores?

I am trying to understand how real time operating systems work. I have looked at the source codes of some RTOSes. I want to learn by creating my simple RTOS, something like FLIRT. I am using PIC16 ...
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Porting Linux Drivers to RTOS

Everybody is probably going the other direction, moving their systems etc. to linux. I have the following problem. I like to use a WiFi chipset along with its Linux driver on my RTOS (FreeRtos). If I ...
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RTOS + Virtual Memory

Given a device that incorporates an embedded processor (MIPS), MMU, small RAM and larger flash memory, is there an RTOS with small memory footprint that has a built in support for "virtual memory", ...
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Change Timer Tick of RTOS - ThreadX

This question is specifically targeted to a RTOS -- ThreadX. We are using it for our project. Problem with this is default RTOS tick time is 10ms which is very high. We need to change it to 1ms. ...
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Replacement for Queues in RTOS

For Inter-task communication or to share data between two tasks of RTOS, We use Queues. But Problem with Queues is that they are slow.... They copy data in Buffer then Mutex Handling and then Data ...
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Has anyone evaluated NuttX RTOS?

While reading Linux User's Journal today, I stumbled across a little blurb about NuttX RTOS. I checked out their website and was fairly impressed with it's feature set and it's ability to put it in ...
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RTOS for Embedded Systems

I have seen many articles that tell me I should be using RTOS for time management and resource management. My time has not permitted my own research, so I come to chiphacker for advice. I use low ...
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RTOS for Arduino?

is there any project of an rtos that works on arduino ?