Will the timed interrupt enter the interruption immediately after it is turned on?

bigbat

Will the timed interrupt enter the interruption immediately after it is turned on? [Copy link]

 

I wrote an application using the GD32F303 microcontroller. My goal is to turn on the TIMER0 timer output after a delay of 1000us after turning on the interrupt.

main
{

   .......

     
	/* enable outq-timer to delaying */
	timer_interrupt_enable(TIMER6,TIMER_INT_FLAG_UP);

   .......


   .......

}



void TIMER6_IRQHandler(void)
{
    if(SET == timer_interrupt_flag_get(TIMER6,TIMER_INT_FLAG_UP)){
			  
			  timer_enable(TIMER0); 
        /* clear channel 0 interrupt bit */
        timer_interrupt_flag_clear(TIMER6,TIMER_INT_FLAG_UP);
			  timer_interrupt_disable(TIMER6,TIMER_INT_FLAG_UP);
        //work_counter++;cur_counter++;   
    }
}

However, after timer_interrupt_enable(TIMER6,TIMER_INT_FLAG_UP); is executed, the program enters the interrupt immediately instead of waiting for 1000uS before entering the interrupt.

May I ask the experts, does it mean that as long as the interrupt is enabled, the interrupt will be entered and wait for the next cycle to interrupt again?

maychang

"When the timed interrupt is turned on, will it enter the interrupt immediately?"

No. The timer will generate an interrupt only when it counts to a certain value.

bigbat

maychang posted on 2022-9-20 18:26 "Will the timer interrupt enter the interrupt immediately after it is turned on?" No. The timer will only generate an interrupt when it counts to a certain value.

I have learned the answer through experiments. After the timer is initialized, that is, timer_enable(TIMER0); is executed, the timer has already started to execute, but the interrupt flag is not turned on at this time, so the interrupt function cannot enter. So as long as the interrupt is turned on, the interrupt can be entered at this time. Because the timer is working at this time, the timer_interrupt_enable(TIMER6,TIMER_INT_FLAG_UP); method cannot be used, but timer_enable(TIMER0); is used to turn on the interrupt, and then the counting starts.

吾妻思萌

They are all program jumps. Whichever statement is jumped to will be executed. It will definitely enter the interrupt function.

秦天qintian0303

1000us? You can observe this too? However, the timer starts working after it is turned on. When the timer reaches the specified time, the hardware will set the flag. However, if you do not turn on the interrupt, it will not be triggered. At this time, if the interrupt is turned on, the interrupt will be triggered, which means that the delay between turning on the timer and turning on the interrupt is greater than the timing time of your timer.

秦天qintian0303

And there is also a problem with your design. Timer 6 will repeatedly interrupt. At this time, it is meaningless to repeatedly open timer 0. You can't design it this way.

damiaa

bigbat published on 2022-9-20 19:15 I have learned this answer through experiments. After the timer is initialized, that is, timer_enable(TIMER0); after this sentence is executed, the timer is already...

The statement timer_enable(TIMER0) may have triggered the update of the automatic reload value.

You can update the auto-reload value or disable and then enable the timer before the interrupt is enabled.

damiaa

/*以前做的一个*/
/*按周期启动定时器2*/
void TIM2_Start(uint32_t tim_period)
{
  uint16_t tmpcr1 = 0;
  tmpcr1 = TIM2->CR1;  
  /* Select the Counter Mode */
    tmpcr1 &= (uint16_t)(~((uint16_t)(TIM_CR1_DIR | TIM_CR1_CMS)));
    tmpcr1 |= (uint32_t)TIM_CounterMode_Up;
    /* Set the clock division */
    tmpcr1 &= (uint16_t)(~((uint16_t)TIM_CR1_CKD));
    tmpcr1 |= 0;
  TIM2->CR1 = tmpcr1;
  /* Set the Autoreload value */
  TIM2->ARR = tim_period;;
  /* Set the Prescaler value */
  TIM2->PSC = 0;
  /* Generate an update event to reload the Prescaler and the Repetition counter
     values immediately */
  TIM2->EGR = TIM_PSCReloadMode_Immediate;  
  /* Prescaler configuration */
  TIM_PrescalerConfig(TIM2, 3, TIM_PSCReloadMode_Immediate);
  TIM2->SR = (uint16_t)~TIM_FLAG_Update;
  /* Enable the Interrupt sources */
  TIM2->DIER |= TIM_IT_Update;	
  /* TIM2 enable counter */
  TIM2->CR1 |= TIM_CR1_CEN;
}

This is one used in previous products. I don't know if it has any reference value. It is from stm32f0 standard library 1.5. It is a direct operation register. It is for higher efficiency.

bigbat

damiaa posted on 2022-9-21 09:23 /*Previous one*/ /*Start timer 2 according to period*/ void TIM2_Start(uint32_t tim_period) { uint16_t tmpcr ...

I used an oscilloscope to see what the naked eye cannot do. My purpose is: there are two switches A and B. After A is turned on, B will delay for a period of time before starting, between 100uS and 5000us. So I use a timer as a control timing, but it seems that the two signals are synchronized. In fact, I want Timer6 to interrupt only once each time it is turned on.

The current solution is to turn off Timer6 in the interrupt. I don't know if it is feasible.

damiaa

bigbat posted on 2022-9-21 09:40 I used an oscilloscope to see what the naked eye cannot do. My purpose is: there are two switches A and B. After A is turned on, B will delay for a period of time before starting. 100u ...

There is no problem with timer 6 shutting itself off after an interrupt.

However, next time you start timer 6 in the main program, you should check to make sure the auto-reload value is reloaded, then enable interrupts and start the timer immediately. In this way, the time can be accurately controlled.

bigbat

damiaa posted on 2022-9-21 09:55 It is OK to shut down timer 6 after it is interrupted. However, you should handle it every time you start timer 6 in the main program to make sure the auto-reload value is reset...

Thank you, should I turn off the reload timer_auto_reload_shadow_enable(TIMER6); and load manually

damiaa

bigbat posted on 2022-9-21 10:09 Thank you, should I turn off the reload timer_auto_reload_shadow_enable(TIMER6); manual loading

You can modify and test it by referring to the initialization code. If it is only once, you should be able to install it manually. You can try it. The code on the 8th floor has also been tested and can be used.

cleverhorse

Depending on the specific situation, you can configure it to enter later or immediately.

fetchstar

In fact, as long as the instruction sequence is correct, there should be no error. That is, first initialize the timer, then enable (allow) interrupts, and finally start counting. That's it.

hustjtj0806

It is timer_enable(TIMER), which executes the timer first and then turns on the interrupt to enter the interrupt state.