Calculate ARR value for Timer TIM2, TIM3 in STM32F407

[Ash1]

Hi

Can you tell me how I can calculate a value for ARR for timer 2(32bit timer) and timer3(16bit timer)

I am using STM32F407 APB1 timer clock is 12MHz prescaler is 6

[Hl_st]

Timer settings seems to be right. Have you done clock configuration in CubeMX? Please check if time clock (APB1 Timer clocks) is really 72 MHz.

Set CKD in (TIMx_CR1) as 00 should be correct

[Andrew Neil]

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@Hl_st wrote:

 check if time clock (APB1 Timer clocks) is really 72 MHz.

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+1

@Ash1 If in doubt, route the clock to one of the MCO pins, and measure it; eg, on an oscilloscope.

[Tesla DeLorean]

Sounds like you're clocking at 100 or 108 MHz, not 72

Check your PLL and HSE relationships 

[Ash1]

hi

Can you suggest me a code in which there is generated interrupt using any timer

[SofLit]

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@Ash1 wrote:

hi

Can you suggest me a code in which there is generated interrupt using any timer

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Time base with interrupt:

https://github.com/STMicroelectronics/STM32CubeF4/blob/master/Projects/STM324xG_EVAL/Examples/TIM/TIM_TimeBase

PS: No ioc file available for this example.

[Andrew Neil]

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@Ash1 wrote:

Can you suggest me a code in which there is generated interrupt using any timer

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The code posted by @SofLit in the very first reply !

[Ash1]

Hi

I have recheked my configuration and found it was 84mhz timer clock instead of 72Mhz

so for 10 second I am loading 0x98967F in ARR and 83 i have loaded in PSC register but still timer is generating UIF flag sometimes in 7 seconds 4 seconds 2 seconds .can you help me Why I am facing this irregular intervals of setting UIF flag

Note :Do i have to set URS bit also in CR1 will it effec