Quality RTOS & Embedded Software

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




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) 2004-2010 Richard Barry. Copyright (C) 2010-2016 Real Time Engineers Ltd.
Any and all data, files, source code, html content and documentation included in the FreeRTOSTM distribution or available on this site are the exclusive property of Real Time Engineers Ltd.. See the files license.txt (included in the distribution) and this copyright notice for more information. FreeRTOSTM and FreeRTOS.orgTM are trade marks of Real Time Engineers Ltd.

Latest News:

FreeRTOS V9.0.0 is now available for download.


Free TCP/IP and file system demos for the RTOS


Sponsored Links

⇓ Now With No Code Size Limit! ⇓
⇑ Free Download Without Registering ⇑


FreeRTOS Partners

ARM Connected RTOS partner for all ARM microcontroller cores

Renesas Electronics Gold Alliance RTOS Partner.jpg

Microchip Premier RTOS Partner

RTOS partner of NXP for all NXP ARM microcontrollers

Atmel RTOS partner supporting ARM Cortex-M3 and AVR32 microcontrollers

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

Xilinx Microblaze and Zynq partner

Silicon Labs low power RTOS partner

Altera RTOS partner for Nios II and Cortex-A9 SoC

Freescale Alliance RTOS Member supporting ARM and ColdFire microcontrollers

Infineon ARM Cortex-M microcontrollers

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

Cypress RTOS partner supporting ARM Cortex-M3

Fujitsu RTOS partner supporting ARM Cortex-M3 and FM3

Microsemi (previously Actel) RTOS partner supporting ARM Cortex-M3

Atollic Partner

IAR Partner

Keil ARM Partner

Embedded Artists