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

The difference configTICK_RATE_HE between 1000 and 100

Posted by hmtsai on September 20, 2015

Hello,

I wonder about the difference with 1000 and 100. If the value is 1000, it means FreeRTOS the kernel tick is 1000Hz. The time's resolution is 1ms. If the value is 100, it tick is 100HZ, The resolution is 10 ms. I set the value is 100, then use vTaskDelay(6/portTICKPERIODMS). It equals no delay. Because the resolution is 10ms. Is it correct? I want to know how to delay 1ms when I set the value is 100. Is it possbile?

Thanks


The difference configTICK_RATE_HE between 1000 and 100

Posted by richard_damon on September 20, 2015

If TICKRATEHZ is 100, and thus TICKPERIODMS is 10, you can not request a delay of 1 ms, as the unit of measure on time is 10ms.

In fact, with a TICHRATEHZ of 1000, and TICKPERIODMS of 1, you can't get an exactly 1ms delay either, as a call to vTaskDelay(1) will block your task till the next tick occurs, which will be AT MOST 1ms, and likely somewhat less. If you need a delay of at least 1ms, you need to call vTaskDelay(2), which will delay at least 1ms, and up to 2ms (or longer if a higher priority task is ready at that point).


[ 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