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TIM14 Period Measurement

Question asked by sotack.john.001 on Dec 22, 2014
Latest reply on Dec 22, 2014 by sotack.john.001
I have an existing STM32F407 family target that has a pulsed signal at PF9.  I need to measure the period of this signal.  This signal has a fixed low time followed by a variable high time.  PF9 can serve as an input to TIM14.  Ideally I would like TIM14 to count up based on an internal clock, capturing and clearing the count on an edge of PF9 (rising or falling but not both).  The firmware would read the captured value for each cycle.  TIM14 would count based on an internal clock.  Any suggestions?  Is this possible with TIMN14.  I known TIM9/12 can measure PWM high and low times.  My need is not to capture both as with PWM input, but a single period.

Presently I have an ISR attached to a falling edge of PF9.  If necessary, I would read the contents of any freer unning timer each time the interrupt occurs and calculate the timer difference.