Quality RTOS & Embedded Software

 Real time embedded FreeRTOS RSS feed 
Quick Start Supported MCUs PDF Books Trace Tools Ecosystem TCP & FAT




Loading

Disable the scheduler giving a task full CPU

Posted by Thomas Johansen on February 24, 2011
Hallo

Is it possible, from with in a task, to stop the scheduler to get full CPU time? After the task has been done, then enable the scheduler again?

I have a buzzer task, that is pulsing an output to make the buzzer sound. But the sound is a bit "uneven" because of the scheduler, taking time from my task. The output must be toggle every 1 ms

Thomas

RE: Disable the scheduler giving a task full CPU

Posted by Richard Damon on February 24, 2011
You can use vTaskSuspendAll() / xTaskResumeAll() to do this, but is sounds like a better solution would be to either make the buzzer task the top priority task (so it will always run when it wants) or move the operation to an ISR on a 1ms timer interrupt.

My first guess is that you probably have FreeRTOS set up with a 1 ms basic timer tick, which is probably faster than you need it if you can set up a second timer interrupt at the 1 ms rate just for toggling this bit.

RE: Disable the scheduler giving a task full CPU

Posted by Richard on February 24, 2011
Just to add to richard_damons reply. If the tick interrupt is fast enough, you have the option of writing a tick hook function and having it done there.

However, normally when I have used things like buzzers I have set up a peripheral (PWM, counter, whatever) to output a signal with the required frequency with no CPU processing required other than to turn it on, off, or change pitch.

Regards.


[ Back to the top ]    [ About FreeRTOS ]    [ Sitemap ]    [ ]




Copyright (C) Amazon Web Services, Inc. or its affiliates. All rights reserved.

Latest News

FreeRTOS kernel V10 is available for immediate download. Now MIT licensed.


FreeRTOS Partners

ARM Connected RTOS partner for all ARM microcontroller cores

IAR Partner

Microchip Premier RTOS Partner

RTOS partner of NXP for all NXP ARM microcontrollers

STMicro RTOS partner supporting ARM7, ARM Cortex-M3, ARM Cortex-M4 and ARM Cortex-M0

Texas Instruments MCU Developer Network RTOS partner for ARM and MSP430 microcontrollers

OpenRTOS and SafeRTOS