ChibiOS Free Embedded RTOS

Posted: **Fri Mar 08, 2013 3:49 pm**

It is possible you problem is external, try to rewite the task as follow:

    while (TRUE) {
             chBSemWait(&semaphore);
            tmStartMeasurement(&TimeMonitor);
            doStuff();
            chThdSleepMicroseconds(5000);
            tmStopMeasurement(&TimeMonitor);
    }

Also note that the measurement has 3 distinct outputs: last, worst, best.

Giovanni

Posted: **Fri Mar 08, 2013 4:07 pm**

Okay, now at least the measurement seems to be correct.
Needed to change CH_FREQUENCY back to 100 as otherwise my periodic CAN output status would sweep between +- 1ms delay.

Without any delay the thread runtime is stable at ~1350us. I just look at the last value. If i add 2000us delay, my measurement sweeps between 2300 and 3400 us. Is this caused by the decreased CH_FREQUENCY?

Posted: **Fri Mar 08, 2013 4:12 pm**

Probably not, it is possible your task is not waked up with the interval you think or you have threads at higher priority interfering with the measurement or some other external condition, The measurement unit itself is extremely simple and I don't see obvious problems with it.

Giovanni

ChibiOS Free Embedded RTOS

Time measurement unit.

Re: Time measurement unit.

Re: Time measurement unit.

Re: Time measurement unit.