Skip to main content
l239955_stm1
l239955_stm1
Associate III
November 4, 2015
Question

Reset timer in Input Capture

  • November 4, 2015
  • 5 replies
  • 1033 views
Posted on November 04, 2015 at 15:16

Hi all,

I´m using timer in Input Capture mode to measure interval between pulses. Actual solution

actualTime = TIM3->CCR1;

if(actualTime > lastTime) delay = actualTime - lastTime;

else delay = 0xffff - lastTime + actualTime;

Is possible to set timer to clear counter after new input pulse?

    This topic has been closed for replies.

    5 replies

    waclawek.jan
    waclawek.jan
    Super User
    November 4, 2015
    Posted on November 04, 2015 at 17:28

    Read the PWM input mode sub-chapter of the Timer chapter. You don't need to set capture on the second channel.

    JW

    Tesla DeLorean
    Tesla DeLorean
    Guru
    November 4, 2015
    Posted on November 04, 2015 at 18:19

    As Jan suggests PWM Input does that. You can use input prescale to have it reset every 1, 2, 4 or 8 cycles, as I recall.

    BTW your math is broken.

    delay = actualTime - lastTime; // Just this works for ALL uint16_t values!!

    Tips, Buy me a coffee, or three.. PayPal Venmo (See Profile) Up vote any posts that you find helpful, it shows what's working..
    mckenney
    mckenney
    Associate
    November 4, 2015
    Posted on November 04, 2015 at 18:26

    >Is possible to set timer to clear counter after new input pulse?

    Don't. If you do your numbers will always be off by something.

    uint16_t new, prev, diff;

    new = TIM3->CCR1;

    diff = new - prev;

    prev = new;

    The magic of 16-bit arithmetic does the rest.

    l239955_stm1
    l239955_stm1Author
    Associate III
    November 5, 2015
    Posted on November 05, 2015 at 13:39

    Thanks a lot, PWM IC is OK.

    -> mckenney.bruce, this solution is not suitable, I´m using Update interrupt to dedicate stopping of the communication.

    Terms & ConditionsAccessibility statement