how to set long delay with use of timer(like up to 5 minute,)

[dbgarasiya]

part number: STM32F779BI

I am using clock frequency 108 MHz ( not system clock , system clock is 216 MHZ)

I don't want to use loop

if not possible what is the maximum value i could set using timer

[waclawek.jan]

In other words, as TIM2 is 32-bit, if TIM2's input frequency is 54MHz, the first tick to TIM3 will come in cca 4'000'000 seconds, which is roughly one and a half month.

JW

[dbgarasiya]

I have follwing changed my code and used another TIM4 as master and same TIM3 as slave

APB1 Clock freqruency is=108MHz

TIM4->PSC=108

TIM3->PSC=1080

TIM4 & TIM3 both are 16 bit timer so ,ARR value is=65535 for both

so accoring to calculation i should get timer 3 will increment at ~71 sec by 1 but i am getting increment at ~143 sec

so what i am going wrong?

[berendi]

Check your clock configuration, because APB1 timer clock is at most 90 MHz.

[Piranha]

Such type of delays are a job for software timers. Software timers with callbacks are absolute necessity for any serious non-trivial project. Therefore implement them once and then use everywhere. Ultimately task scheduler and software timers changes software architecture and your way of thinking forever and enables you to write actually useful systems, not only Arduino style "Hello world!"-s.

[waclawek.jan]

If APB divider is not 1, TIM is usually not clocked at APB clock but at twice that. Read the RCC chapter.

JW

[dbgarasiya]

Thanks to all of you @Community member​  ,@berendi​  ,@turboscrew​ ,@Community member​  for your support

[dbgarasiya]

I have total 14 timers in my controller ( STM32F779BI) , I have done some timers as master-slave configration

but some timers have not master-slave configration functionality

and i know that prescaler valu maximum goes up to , i could generate maximum value of 1 millisecond

but i want to make timer of 10 milliseconds . i tried but i am getting delay of 10 ms after setting prescaler and period value

Timer clock : 108 MHz & 216 MHz , both are used for diffrent timers

how could i do that?

Dipak Garasiya

[berendi]

These are the limitations. You can slow down the APB clocks, or implement longer delays in software.

[turboscrew]

Cascade the timers. Make one of them tick and the other to count the first one's UGs (milliseconds), not APB-clock ticks.

Now you have a longer timer, even if in two parts.

[dbgarasiya]

I have configured timer 6 as below, my timer clock frequency (APB1) is 108 MHz

RCC->APB1ENR |= (1<<4);   // timer 6

TIM6->PSC = 108;

TIM6->EGR = TIM_EGR_UG;

TIM6->ARR = 10000;

TIM6->CR1 = TIM_CR1_CEN;

count = TIM6->CNT ;

I am not getting 10 millisecond of timer yet

[turboscrew]

The counters start from zero. Try PSC=107 and ARR=9999. Any closer?

[dbgarasiya]

@turboscrew​  that is also not getting 10 milliseconds of timer

[berendi]

Are you going to tell how long is it then, or do we have to guess?

[dbgarasiya]

it is appoximately 333 us of timer with this configuration .

while (1)

{

HAL_Delay(1000);

Timer6_Read();

//Read_All_Timers();

}

i have written my code as above for reading timer count

terminal screenshot i have attached with this post

[turboscrew]

In that case, check your clock tree.

[dbgarasiya]

I have used timer 6 which is clocked by timer clock register is RCC_APB1ENR

like this

RCC->APB1ENR |= (1<<4);  // timer 6 which is 108 MHz

i am attaching you my clock configuration sceenshot for this, so you will get better ide about this