MSP430 G2553 Launchpad to implement capacitance measurement

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MSP430 G2553 Launchpad to implement capacitance measurement [Copy link]

I. Basic Principles As shown in the figure above, the general steps are: 1) GPIO charges capacitor C to Vcc through resistor R; 2) The GPIO outputs 0, capacitor C discharges through R, and the Timer starts timing and CA+ is turned on; 3) When the capacitor voltage is discharged to the reference voltage (here is 0.25Vcc), the level changes at the comparator CA+ output; 4) The interrupt program captures this change, and uses the capture mode of the Timer to obtain the time at that moment, and finally calculates the capacitance value through the above equation. In the figure above, it is recommended to use a 1% precision resistor for R to improve the test accuracy. III. State Transition Diagram