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[FreeRTOS Home] [Live FreeRTOS Forum] [FAQ] [Archive Top] [October 2016 Threads] In Tickless Idle Mode Expected Idle Time is always less then 4Posted by rahimoval on October 7, 2016 Hi all,
I am using freeRTOS version 9.x.x on Freescale Cortex-M0+ port. I have configured tickless idle and using systick as normal context switch timer and during tickless idle the systick is deactivated and MCU specific 16 bit low-power timer (LPTMR) is activated to wake the MCU and make time adjusments to tick. It is working, but one problem which I heve is that in SuppressTickAndSleep the parameter xExpectedIdleTime is always less then 4, which is very short to put the MCU in LP-Mode. I am using timers with long periods (30 mins) and other my application tasks are blocked on queues waiting for messages. What am I doing wrong? Why the expected idle time is very short in my case?
Thanks in advance for your answers
In Tickless Idle Mode Expected Idle Time is always less then 4Posted by xz8987f on October 8, 2016 Hello,
I would say that you have something running with a period of about 4 ticks? Are you sure you don't have a task or FreeRTOS timer running at the frequency. If you are debugging it with a Segger probe, you might use their SystemView (https://mcuoneclipse.com/2015/11/16/segger-systemview-realtime-analysis-and-visualization-for-freertos/) to see what is going on. If you are using Eclipse, then a Kernel awareness might be helpful (see https://mcuoneclipse.com/2016/07/06/freertos-kernel-awareness-for-eclipse-from-nxp/ and https://mcuoneclipse.com/2016/04/09/freertos-thread-debugging-with-eclipse-and-openocd/). I had a similar problem in the past in a huge software project where a task was polling a semaphore instead of using a larger timeout: that polling thrashed pretty much longer idle time.
I hope this helps,
Erich
In Tickless Idle Mode Expected Idle Time is always less then 4Posted by rahimoval on October 8, 2016 Hi,
thanks for your reply. I found the problem. My tasks were blocking on queues with limited delay times (exactly 5 ticks). I have defined these delay times to port max delay and everything seems to be ok now. Thanks for your links. I'll definitely look through them
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