Comparator to trigger ADC collection

[mindcrusher]

triggering adc with timer

Hello,

I am new to the microncontrollers and electronics and I would apreciate some advice.

I need to sample data from PZT sensor using an MSP430 microcontroller. Since I can't monitor the ADC port continuously I want to use a comparator that needs to trigger an interrupt starting the data sampling in the MSP.
I am wondering what will be the effects on the received signal if I am using the comparator on the analog line. Between the sensor and the ADC I have a charge amplifier with a 100 ohm output impedance.

 

[VVV]

adc collection

How would the comparator trigger the ADC, based on what changes?
Why not set up a timer and read the ADC evry x ms or seconds? This is what I would do. Set up a timer to generate an interrupt and when that happens read the ADC.

 

[mindcrusher]

trigger adc

The PZT will generate a signal after an event has occurred. I am interested in measuring the specific event. As the event takes place at random time intervals the best data recording trigger will be when the voltage on the line passes a certain threshold (indication of an event) and therefore I thought the best solution will be a comparator.