low-level TIM conflict with Chibio?

[Giovanni]

What compiler/version are you using? is FP enabled in your application?

Giovanni

[russian]

I am using latest codesourcery - that's GCC 4.8.x. Yes I use floating point, and most of my logic (and stack usage) in in the interrupt handlers.

While I would probably need to increase even the proposed larger defaults, I still believe the current extremely low defaults are not perfect, they are probably causing issues for too many unsuspecting naive users.

[russian]

Probably not related to Chibi at all, here's another issue I am having with the same code:

I am not getting an interrupt in case of small auto-reload register value:

Code: Select all

void initMicrosecondTimer(void) {
   RCC ->APB1ENR |= RCC_APB1ENR_TIM5EN;   // Enable TIM5 clock
   nvicEnableVector(HW_TIMER_IRQ, CORTEX_PRIORITY_MASK(HW_TIMER_PRIORITY));
   TIM->DIER |= TIM_DIER_UIE;   // Enable interrupt on update event
   TIM->CR1 |= TIM_CR1_OPM; // one pulse mode: count down ARR and stop
   TIM->CR1 &= ~TIM_CR1_ARPE; /* ARR register is NOT buffered, allows to update timer's period on-fly. */

   TIM->PSC = 84 - 1;   // 168MHz / 2 / 84 = 1MHz, each tick is a microsecond
}

/**
 * sets the alarm to the specified number of microseconds from now.
 * This function should be invoked under kernel lock which would disable interrupts.
 */
void setHardwareUsTimer(int timeUs) {
   TIM->ARR = timeUs - 1;
   TIM->EGR |= TIM_EGR_UG; // generate an update event to reload timer's counter value
   TIM->CR1 |= TIM_CR1_CEN; // restart timer

   lastSetTimerTime = getTimeNowUs();
   isTimerPending = TRUE;
   timerRestartCounter++;
}

So, everything works as a charm if timeUs is 300 and above - that's 300us between timer restart and the callback. But if I try values like 5 or 11 - the callback never happens. Just for clarity: I am not even trying to constantly invoke 5us, 5us, 5us, 5us - even a single 5us after numerous 300us invocations fails to produce a callback.

Currently I am trying relatively low #define HW_TIMER_PRIORITY 12 but I was still expecting the callback to happen eventually?

Please advice how can I get the callback to happen, even if it would be a bit late.

[Giovanni]

What are you trying to do? it looks something like the GPT driver.

Giovanni

[russian]

Yes that's pretty much gptStartOneShot, I've forgotten what has scared me away from using it, let me give it a try

[russian]

I've migrated my code to gptStartOneShot and things are looking up.

Only one question: 'interval period in ticks'
Is it supposed to work as "gptStartOneShotI(&GPTDEVICE, 1);" - i.e. with interval = 1? Because it does not work for me like that - the callback never happens. Works with any other parameter.

I know that the implementation is

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  gptp->tim->ARR   = (uint32_t)(interval - 1);  /* Time constant.           */

but one tick seems to be a valid parameter, is not it?

[Giovanni]

Not sure if it is valid, have to look into the RM.

Giovanni