Actually i just need it to use in my RPM counter program ,the loop which need to be executed is a repeated count loop that add a variable everytime a pin becomes LOW.(which i use a photosensor to scan the revolution per minutes for my ＤＣ motor).i use PIC16F877 and 4MHZ crystal for my application
So for a certain time (1 minutes ) i know that how many times my motor slice has through my sensor ,by this way i can know the RPM of the motor,or is there any other way i can achieve that?Thanks.