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


Semaphore times out

Posted by ARMinator on March 22, 2009

I have added a tick hook that counts ticks and give a semaphore periodically using xSemaphoreGiveFromISR.

A task waits on this semaphore using xSemaphoreTake and the maximum delay (portMAX_DELAY).
I have an LED that shows when the semaphore is given and an LED showing when the semaphore is taken.
The semaphore is given consistently from the ISR (the ISR LED blinks). You would expect the task LED to blink too... However the semaphore is only taken once from the task. All other tentatives to take the semaphore pend forever, or timeout if I use a timeout value other than portMAX_DELAY.

This issues occurs whenever I use binary or counting semaphores.

Any idea what is going wrong?


RE: Semaphore times out

Posted by ARMinator on March 22, 2009
I thought I would also say that I tried to add the following code and it still fails:

xSemaphoreGiveFromISR(mySemaphore, &dummy);
if(pdTRUE == dummy)

RE: Semaphore times out

Posted by Dave on March 22, 2009
Which port are you using (CPU and compiler). Which version of FreeRTOS are you using? Can you post your code?

[ 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