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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How to flush an RTOS queue and prevent further posting on a device disconnect event?

In the following code SendMessage() is the API called by the user to send a message over USB Task() is the thread created in ...
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39 views

Events in FreeRTOS 7.1.1

I'm looking for method how to inform one task in firmware about change somewhere else (Using FreeRTOS 7.1.1). I need to receive information about changes, but I wouldn't want check value in cycle - ...
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SD Card Buffer in FreeRTOS

One of my tasks in project is resposible for gathering information about values measured from sensors and write information in .txt file on SD Card. I've got question, how would be the most correct ...
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69 views

Queues in FreeRTOS

I have multiple tasks that all write to a screen. Obviously without controlling who can write to the screen when I'll have problems. I thought the easiest way to do this was with queueing. I have a ...
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19 views

Nested function scheduling using RTOS

I am trying to implement a Wireless RFID protocol onto a RTOS using Texas Instruments cc430. the protocol has its own stack and at the time being, uses timers to send and receive packets. I am trying ...
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44 views

Calculating processor utilisation

I'm using a Cortex M3 processor on an LPC1769 board. For this particular situation, all processes occur within interrupts. Therefore, within the main "loop" there isn't actually anything to be ...
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53 views

Measuring time using an STM32F407VGT6 microcontroller

I'm using a custom board for charging and testing batteries. Its 'brain' is an STM32F407VGT6 microcontroller. I'm developing in Ubuntu (14.04.2 LTS), using ChibiStudio (ChibiOS/RT 3.0 development ...
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3answers
207 views

interrupt using Timer0 on PIC18f

Im looking for a little help and advice on my code. Im using C18 in the MPLab environment, PIC18f4520 with Fosc @ 4MHz, and usnig timer0 in 16 bit mode to count to overflow, set the overflow bit and ...
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72 views

Does priority inheritance cure priority inversion?

In the Mutex description page of the FreeRTOS website the following sentence can be find: Priority inheritance does not cure priority inversion From what I know I thought that priority ...
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129 views

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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179 views

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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625 views

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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75 views

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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2answers
115 views

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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2answers
717 views

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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109 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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88 views

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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251 views

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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45 views

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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1answer
389 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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3answers
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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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137 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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2answers
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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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185 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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280 views

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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2k 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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1answer
451 views

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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2answers
502 views

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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3answers
1k views

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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3answers
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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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1answer
2k views

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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1answer
581 views

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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3answers
1k views

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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6answers
497 views

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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2answers
4k views

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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9answers
3k views

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 ?