According to the data sheet pic16f877 has two capture modules. It is mentioned (page 1 of the data sheet) that the maximum resolution of the capture module is 12.5ns.
It means the minimal time difference between two captures hast o be 12.5 nano seconds
The CCP module (in capture mode) records the current value of a 16 bit timer the moment you put it's respective CCP pin to high (or low if set up by software).
It means the minimal time difference between two captures hast o be 12.5 nano seconds
The CCP module (in capture mode) records the current value of a 16 bit timer the moment you put it's respective CCP pin to high (or low if set up by software).