Hi, Controller works o | Microcontroller › 8051 › How to make an alphabetic keypad using 8051 microcontroller (AT89C51) › Hi, Controller works o May 6, 2014 at 3:46 am #11685 SHAH DISHANT H.Participant Hi, Controller works o crystal frequency which decides operating speed of it. PIN18 and 19 are the two pins at which we have to connect crystal of dsired frequency. Both pins should be connected with 20th pin (ground) via a capacitror of 33pf.
