ChibiOS Free Embedded RTOS

Posted: **Thu Oct 17, 2013 2:25 am**

I am using the stm32f373 virtual timers.
The strange stuff

On the bench with short sensors wires the code works correctly.
All timers are set, and all set timers expire and trigger their coresponding call back.

On the vehicile with long inductive sensor wires the code does not work correctly.
All timers are set, but only the first timer expires and triggers its coresponding call back.
The other timers are set, but do not expire and trigger their coresponding call back.

The timers are set in an ICU callback.
To me this looks like a race condition, caused by the ICU callback triggering too often because of noise on the long inductive sensor wires. How should I add locking to prevent timer race conditions? Assuming that is the problem, could the problem be something else?

Posted: **Thu Oct 17, 2013 8:21 am**

Are you running with debug options enabled? if there is a race condition probably it is because a call protocol violation somewhere.

Also, using VTs in a wrong way can lead to a corruption of the delta list, for example you should not set a timer that is already running etc, you should look for problems of this kind too.

Giovanni

Posted: **Thu Oct 17, 2013 12:49 pm**

Here is the VT usage.
I check or reset before setting the timer.

Does chVTSetIsr and chVTResetIsr used here need chVTIsArmedI checking?

Code: Select all

const ICUConfig HazardSensorConfig = {
        .mode = ICU_INPUT_ACTIVE_HIGH,
        .frequency = HAZARD_FREQUENCY,
        .width_cb = NULL,
        .period_cb = HazardPeriodCB,
        .overflow_cb = NULL,
        .channel = HAZ_TIM_CHANNEL
};

Code: Select all

static void HazardPeriodCB(ICUDriver *icup)
{
    (void) icup;
    chSysLockFromIsr(); 
    if (chVTIsArmedI(&vtsample))
    {
        chSysUnlockFromIsr(); 
        return;
    }
    chVTSetIsr(&vtsample, MS2ST(100), TimerFlashSample, NULL); 
    chVTResetIsr(&vtoff);
    chVTSetIsr(&vtoff, S2ST(dbGetTimeoutHazOff()), TimerFlashOff, NULL); 
    chVTResetIsr(&vtcancel);
    chVTSetIsr(&vtcancel, S2ST(dbGetTimeoutHazCancel()), TimerFlashCancel, NULL);
    chSysUnlockFromIsr(); 
}

Posted: **Thu Oct 17, 2013 1:07 pm**

Hi,

Before calling chVTResetI() you need to verify if the timer is active: The timer MUST be active when this function is invoked.

Giovanni

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