Quality RTOS & Embedded Software

 Real time embedded FreeRTOS RSS feed 
Quick Start Supported MCUs PDF Books Trace Tools Ecosystem


event group

Posted by williamjsell on February 10, 2014

I have a call in my task:

    uxBits = xEventGroupWaitBits(
                xCalibrationGroup,   //The event group being tested.
                CALIBRATE_4_20 | CALIBRATE_MCHAN |
                CALIBRATE_5VDC | CALIBRATE_10VDC | CALIBRATE_BDTEMP | CALIBRATE_RTD, //The bits within the event group to wait for
                pdFALSE,         //bits are cleared after the module has been run
                pdFALSE,        //any bit will cause the task to run
                xTicksToWait ); //Wait forever

When I start the scheduler, the task executes, but no bits are set. uxBits == 0x0. So I am not clear on the function of the event group, I thought it would allow for the task to process only when one of the flags was set.

event group

Posted by rtel on February 11, 2014

With the parameters set as shown, the task calling that code should remain in the Blocked state for a maximum of xTicksToWait for any one of the CALIBRATE420, CALIBRATEMCHAN, CALIBRATE5VDC, CALIBRATE10VDC, CALIBRATEBDTEMP, CALIBRATE_RTD bits to be set (assuming those constants are defined to single bit values).

Has the event group been created before you used it? How do you know uxBits is 0? What is xTicksToWait set to?


event group

Posted by williamjsell on February 11, 2014

I had xTicksToWait set to 0, but I changed this to portMAX_DELAY and now it is working...thanks!

[ Back to the top ]    [ About FreeRTOS ]    [ Privacy ]    [ Sitemap ]    [ ]

Copyright (C) Amazon Web Services, Inc. or its affiliates. All rights reserved.

Latest News

FreeRTOS v10.2.0 is available for immediate download. MIT licensed, and including RISC-V and ARMv8-M (Cortex-M33) demos.

NXP tweet showing LPC5500 (ARMv8-M Cortex-M33) running FreeRTOS.

View a recording of the "OTA Update Security and Reliability" webinar, presented by TI and AWS.


FreeRTOS and other embedded software careers at AWS.

FreeRTOS Partners

ARM Connected RTOS partner for all ARM microcontroller cores

Cadence Tensilica Cortes

Espressif ESP32

IAR Partner

Microchip Premier RTOS Partner

RTOS partner of NXP for all NXP ARM microcontrollers





STMicro RTOS partner supporting ARM7, ARM Cortex-M3, ARM Cortex-M4 and ARM Cortex-M0

Texas Instruments MCU Developer Network RTOS partner for ARM and MSP430 microcontrollers

OpenRTOS and SafeRTOS

Xilinx Microblaze and Zynq partner