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

receiving corrupt data with xQueueReceive

Posted by Mohammad on September 30, 2012
Hi everyone,
i have the following problem:
i dont receive the same data with xQueueReceive, that i sent it with the xQueueSend.
here is the code, maybe someone can help me solving the problem:

void privateMenuCreateRefreshEvent(unsigned char pattern, unsigned char field, unsigned int sensor, unsigned char value)
{
struct Display_Message SendMessage;
struct DataFieldUpdate *pointer = malloc(sizeof(struct DataFieldUpdate));
pointer->fieldNumber = 0;
pointer->patternType = 0;
pointer->valueID = 0;
pointer->valuetype = 0;
SendMessage.DataFieldObject = pointer;
SendMessage.Msg_Type = ProtocolData_Object;

xQueueSend(xDisplayQueue,&SendMessage,0);
free(pointer);
}

and the receiving task:

void dplTask(void *pvParameters)
{

for (;;)
{
struct Display_Message *ReceivedMessage = malloc(sizeof(struct Display_Message));;
xQueueReceive(xDisplayQueue,ReceivedMessage,portMAX_DELAY);
if ( ReceivedMessage->Msg_Type == ProtocolData_Object )
{
dplUpdateDisplayExecuteFunction(ReceivedMessage->DataFieldObject);
free(ReceivedMessage);
}
}
}

the ReceivedMessage->DataFieldObject dont have the same values that are sent in the example above.

what could be the problem here.

Best Regards.

RE: receiving corrupt data with xQueueReceive

Posted by Richard Damon on October 1, 2012
When you queue up SendMessage, the contents of the structure itself are copied into the queue, which will include the value of the pointer SendMessage.DataFieldObject. It does NOT make a copy of the DataFieldUpdate object. When you then do the free(pointer) the memory holding the values are returned to the heap, and possibly overwritten.

You should NOT do the free(pointer) at the sending side, but leave the DataFieldUpdate object on the heap, and when the data is received and processed, you then free the object on the receive side before the free(ReceviedMessage).

RE: receiving corrupt data with xQueueReceive

Posted by Mohammad on October 1, 2012
thank you very much richard.
i changed the struct Display_Message SendMessage and made the DataFieldObject in it not as a pointer. because i need about 30 queue-item for this queue and some items must wait until they will be processed. and now it is working very well.
thanks again.


[ 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