Choosing a timer and what mode for only counting time periods.

You don't need any channels to get a periodic interrupt.

Set the Prescaler to clock the TIM at 1 MHz, set the Period to 100-1, enable the Update interrupt, and you'll get an interrupt every 100us

Depending on the APB clock, but Prescaler = (SystemCoreClock / 1000000) - 1   ie figure source divided by 1 MHz to get divisor for 1 MHz

If you run the TIM with maximal period, you can use and advance the channel triggers by 100 at each interrupt for similar effect, but it is more labour intensive.

Use a basic timer to do this, with interrupt on overflow. Use the smallest timebase for tuning the overflow. Then if you want to create a countdown, in the interrupt, decrease a 32 bit global variable unless it is 0xffffffff

From the main loop you will have a simple timeout counter that will self stop.

Hi Eugenia,

The STM32 microcontrollers family have different timers with different features, but all of those with the basic feature of free counting. If you're using the STCubeMX software, in the pinout tab you can see the features of each timer, and for example you can see that TIM1 to TIM5 have the special features as PWM, output compare and input capture that includes the use of channels for signal input / output, if you don't need a signal then there is not necessary to set any channel. There are other timers that have only  the counting mode and the one pulse mode. If you want to make a time count I suggest to use the basic timers, you just check the option ''activated'' and set the parameters (prescaler and counter value that depens of the clock frequency) in the Configuration tab and the interruption. If you want to use a timer with the special features just for free counting in the pinout tab select the timer (for example the TIM1) and then just select the clock source, the TIM1 is now activated and you can set the p

arameters in the Configuration tab and the interruption (prescaler and counter value that depens of the clock frequency).

yes, in summary, you must use a single timer for your 100uS timerOverflow interrupt.

there is no point to use channel compare, because they go active at the count and deactivate at a count of zero, therefore the overflow rate is determining the frequency, not the channel 'compare value'

Dear Sir/Madam:

I just found that I have similar problems.  there are limit timers . timer 1, timer9 and timer10 are different from other timers. I have used timer2, timer3, timer4, and timer5 and their interrupts . to each timer, I use internal clock ,

once timers expire, they will create interrupt. My questions are

1. each timer , I only use one channel, there are more channels available, but I want their periods are different,

in my understanding, if you use multiple channels from one timer, their period have to be the same?

if not same, how could I do that? and how could I enable or disable each channel to separate them?

2. if above 1 does not work for multiple channels from one timer, I try to use different timer for each event,

but I found that I could not make  timer1, timer9 and timer10 work for their interrupt

I could only make timer2, timer3, timer4 and timer5 interrupts work.

1. here are my configures for working timers' interrupt:

/*########## Configure TIMx x = 2,3,4,5 ######################################*/

void TIMx_IRQHandler()

// Timer is configured to rollover every 1 secs 

TimxHandle.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;

HAL_NVIC_SetPriority(TIMx_IRQn, 0, 1);

2. here are my configures for none working timers' interrupt:

/*########## Configure TIMy y = 1,9 ######################################*/

TimyHandle.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;

HAL_NVIC_SetPriority(TIM1_BRK_TIM9_IRQn, 0, 1);

would you please help me for that.

now basically , I would need use at least 8 timers' interrupts. 

thanks for all of your

rose

Dear Dhenry:

further reading your response, I guess :

in my settings , i have period value for a timer, and then I could set 

channel = channel1|chnnel2...; 

period = n tickes; // I guess this is ticks, or period

in the timer interrupt,

suppose channel 1 has period n ticks , channel 2 has 2n ticks

1. check whether it is the timer I configure

2. check whether it is channel1, if so check its counting? (like n) if so, it is for channel1?

3. check whether it is channel2, if so check its counting (like 2n) if so, it is for channel2?

am I correct?

since I use HAL lib, I may need to read __HAL_TIM_GET_COUNTER(&TimxHandle) inside ISR

to get countings?

thanks 

roseanne

dear Eklin and Clive:

yes, I have to use timer interrupts for some time sensitive modules(tasks) inside the interrupt routine, the current tasks' levels(main loop without OS), some tasks take too long, and make other tasks, which need to process some data in exactly time, miss executions and results are bad. this is one reason, another reason, in the task level, it is related to communication with outside interface, we have to use timer to avoid waiting time out, there are other reasons.

this is micro controller which handle 3 hardware serial interfaces to communication outside, and adc and dac interface involved and some math calculation. I have to weight all the tasks and interrupt routines...

Dear Dhenry:

thanks, I will read your codes in more details.

thanks

Dear Eklin:

thanks for your reply. 

So far I do not have problems to set most interrupts and balance between tasks level  and interrupt. The balances among interrupt latency and context switch are all very good so far which really solve our purely poll 's structure .  HAL api gives very good interrupts' flag cleaning and setting . The only problem is limit timers I could use. So now I have to utilize multiple channels for each timer . I am still reading Mr. Dhenry's examples to know how to use HAL's API to set each channel of one timer .

since we also have ADC interface, if I could use ADC interrupt for its timing, I may not need to use so many timer's interrupts. 

will let you know how about my progress.

thanks

roseanne

Dear Elkin and Dhenry:

I used the similar function you gave for Hal callback function for timer update(expire), I do not have the problem so far

I am struggling to try to use multiple channels of one timerf 

I read back HAL lib: 

void HAL_TIM_IRQHandler(TIM_HandleTypeDef *htim)

                                                                                                channels of one timer

.....

                                                                                      one timer, I do not think that I need to use this one.

....

=======================================================

so if I am correct, I will use 

HAL_TIM_OC_Start_IT(&Tim3Handle, TIM_CHANNEL_1); <==========enable channel 1 interrupt of timer 3

                                                                                           used for a timer expire, not for their channel

by reading from your codes, it seems that 

every time , once interrupt happen for a channels , I need to update output compare register count inside compare interrupt of 

HAL_TIM_OC_DelayElapsedCallback(htim);, but if compare register's data is over flow, I may need to reset the data again.

I am still trying to test this, if I am wrong, please let me know.

thanks for your help

thanks

rose