hi,
can someone explaine me, what does PRESCALER actually do in pic18f4331.. particularly in timer application.....plz xplaine in detail....

 

Think of the PRESCALER as a clock divider. Do you want to count every pulse? Then turn off the prescaler. Do you want to count every other pulse? Then set your prescaler at 1:2. Do you want to count every 256th pulse? Set your prescaler at 1:256. You can do this by setting the appropriate bits in the timer registers.