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


RTOS viewer error name = "ÿÿÿ"

Posted by uCElia on February 15, 2013
I'm new in forum.
I'm a software developer for microchip microcontroller and some times ago I choose to try freeRTOS.
In my actual project an error occur: the program run for some hour than a task seems every Blocked and IDLE task running.
In particular the task that is in Blocked State should wait for message send in a Queue, but Queue become full after some hours and any Send return Error.
I try use debugger to undestand this strange behaviour so I take RTOS viewer plugin for MPLABX 1.60 and the result is unbeliveble!
I add the Queue and the Semaphore to register for debug every possible blocker situation, but the IDE show wrong info about pointer to queue and his names. In particular in the name of queue there are ÿÿÿ character and the dimension seems some kilo or mega messages despite of 5.
If I watch task register I saw that a TASK disappear and there are multiple instances (two) of a task.
I work with XC16 compiler in MPLABX. The PIC family is PIC24F.
Can someone help me?

RE: RTOS viewer error name = "ÿÿÿ"

Posted by Richard on February 15, 2013
A similar problem was highlighted recently here:



RE: RTOS viewer error name = "ÿÿÿ"

Posted by uCElia on February 15, 2013
I'm sorry, I've seen that topics, but my problem is difference. I found and follow in link you suggested and similar topics.
In that topics the problems regard the impossibility to see the task, but I see all my task, only after some hours task disappear and entire system lock in Idle state.
The Top description is for the first problem: I don't understand why that task stop and disappear.
The second is the wrong information about QUEUE state. It seems take not initialized RAM data: all information about QUEUE name, pending messages, dimension of Queue are false.

RE: RTOS viewer error name = "ÿÿÿ"

Posted by Dave on February 15, 2013
If the plugin works for a while then stops at the same time your program does it is likely that your program is stopping due to some serious data corruption. If the plug in works the same as the Eclipse plug in then it gets its data by querying the PIC RAM. If the PIC RAM is corrupt the plugin is going to read and then display corrupt data. Just a guess.

RE: RTOS viewer error name = "ÿÿÿ"

Posted by uCElia on February 18, 2013
Thank You davedoors.
It's possible that the RAM data is corrupted, this can explain the wrong data information.
My doubt was if the problem is in PIC or in the plugin or in IDE.
Also the tasks problem can be explain by RAM problems, but is there a solution?

RE: RTOS viewer error name = "ÿÿÿ"

Posted by Dave on February 18, 2013
Do you have stack checking turned on? http://www.freertos.org/Stacks-and-stack-overflow-checking.html

RE: RTOS viewer error name = "ÿÿÿ"

Posted by uCElia on February 18, 2013
Ops, I've got the vApplicationStackOverflowHook(), but I forget to active it in "FreeRTOSConfig.h".
Now I'm trying first method...

RE: RTOS viewer error name = "ÿÿÿ"

Posted by uCElia on February 19, 2013
I try to cacth stack overflow, but there are never stack problems. Simply in my system after some times (from some minute to some hours) a task is left and need a restart.
Now I think this is not a RAM problem because from system start I can't see the Queue information despite Task correctly displayed by RTOS viewer.

RE: RTOS viewer error name = "ÿÿÿ"

Posted by Richard on February 19, 2013
There are certain things that you have to take care of, most of which are documented here:

In particular on the PIC32 you have to ensure that all the interrupt service routines that make use of the interrupt safe FreeRTOS API (functions that end in "FromISR" are interrupt safe) have a priority that is not greater than the configMAX_SYSCALL_PRIORITY setting in FreeRTOSConfig.h.

Other than those generic items, I would need a lot more information about your system to be able to assist further. You could start by providing information on the structure of your tasks.


RE: RTOS viewer error name = "ÿÿÿ"

Posted by uCElia on February 21, 2013
I use a PIC24F not a PIC32, and I don't find "configMAX_SYSCALL_PRIORITY", but I'm reading the "FAQHelp.html".
I think the problem can be my "configTICK_RATE_HZ", I change it from sub-kHz to 3kHz. I have to change interrupt configuration to set that RATE and set

#define configUSE_16_BIT_TICKS0

Another problem can be due to interrupt priority, it can be too high.

I try to solve theese problems.

Thank You

[ 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