Joe Burch

Using the 908JL16 Input Capture Feature to Measure Low Frequency Tones (e.g. 67.0 to 250.3 Hz)

Discussion created by Joe Burch on Sep 22, 2010
Latest reply on Oct 1, 2010 by bigmac

Hello folks,


I would like to ask another question on using the timer capabilities of the JL16 to measure these low frequency tones.


In reading the literature, it would appear that one method would be using the input capture capability.  Would someone be so good as to provide some high level advice as to how this might be accomplished by measuring the period?  In the case of a 250.3 Hz tone, the period is around 4 ms.


I guess that I'm somewhat confused about the input capture timing mechanism.


I've tried several approaches.  One was using one of the timers (TIM 2) to generate an interrupt every 100 ms and another TIM1 input compare interrupt to count the 'compares' generated every 100 millisecond interval.  After 10 TIM 2 interrupts, I thought I would end up with something close to the measured frequency.  It didn't work that well.


Thanks, in advance, for your help.


Joe Burch