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

Ticktimer overflow issue

Posted by olibats on September 28, 2007
Hello,

I am running freeRTOS in preemptive mode. Assuming my system will run a very long time without a restart I have come to the conclusion that xTickCount could overflow. I tried to provoke this by using 16 bit tick counter and see what happens to my RTOS and tasks.

For what I have seen everything looks good. No fault times where no task is executed or else.

Nevertheless I am asking you, if somebody knows if there is any other issue concerning long time runs.

Also I am asking about the configTOTAL_HEAP_SIZE, which seems to have absolutely no influence on the system. (Which might be because I am using the heap_3.c??).

Thanks,
Olibats

RE: Ticktimer overflow issue

Posted by Richard on September 28, 2007
First - you are right - configTOTAL_HEAP_SIZE has no influence when using heap_3.

Regarding the tick count overflow - everything internal to FreeRTOS.org is designed to cope with the tick count overflowing so you have no worries there. This was checked out very thoroughly during the SafeRTOS testing process, and actually resulted in a minor change to the FreeRTOS.org code to fix a glitch that could have occurred once in a billion billion years (i.e. extremely unlikely).

Naturally if your application code itself (as opposed to the kernel code) makes use of the tick count value then it has to be aware of overflows just as if it used any other timer. There is actually an undocumented feature that can assist with this - take a look at how the queue code uses the vTaskSetTimeOutState() and xTaskCheckForTimeOut() functions.

Regards.

RE: Ticktimer overflow issue

Posted by olibats on October 1, 2007
Hi,

Tanks for your comment. I put my mind at rest on this issue.

Thanks for the Hint with those methods. Since I have to work with the TickCount I am almost sure I will need them.

Thanks again,
Olibats


[ 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