Influence of pre frequency division value and automatic reload value on interrupt frequency

ARR—— Automatic reassembler ;

PSC—— Preassigned frequency counter

These two are also deciding TIM Parameters of timing time , If we want to decide 1s Time for , You can refer to the counter overflow frequency formula ：CK_CNT_OV=CK_CNT/(ARR+1)=CK_PSC/(OSC+1)/(ARR+1)

That is to say , Timing frequency =72M/（PSC+1）/(ARR+1)

timing 1s, That is, the timing frequency is 1hz,PSC Give me a 7200,ARR Give me a 10000, Then two values are subtracted 1, Because prescaler and counter have 1 Number deviation , So subtract 1

( Be careful PSC and ARR All values of must be in 0~65535 Between , Don't go beyond the scope )

Give less prescales , Auto reload to multipoint , In this way, there are more numbers calculated at a higher frequency ;

If the prescaler gives more points , Auto reload to less , This is a relatively small number based on a relatively low frequency ;

If our auto reload value is 10000-1, Then this value is from 0 From... To 9999, The total is

10000 Number , Count 10000 Time , Namely 1s.

If we put 10000 Change to 1000, It's from the hospital 10000 Number , Become a plan 1000 Number , At this time, the value is from 0 Add to 999 了 , The corresponding is 0.1s, When the prescaled value remains unchanged , The value increases faster than before 10 times

If we change back to 10000, Remove one of the prescaled values 0, That is, based on the original 10 Times counting frequency meter 10000 Number .