8051 based frequency counter is a mono signal frequency counter which can count from 1 Hz to 470 kHz. It operates only on square wave no matter what the duty cycle is. The circuit uses both of the 8051 timers, one as timer and other as counter. Timer0 provides the time base which is set to 1sec via multiple interrupt counting and timer1 configured as a counter which counts the external frequency. The count is displayed in an LCD module.
1) Power Supply: This section is responsible for providing required power for the working of entire project. This section consist of 12V step-down transformer, bridge rectifier with capacitor filter, 7805 voltage regulator and an indication LED. 2) Micro controller: The AT89S52 microcontroller is the central processor. The micro controller has three timers and two of them are used in this project. Timer 1 is configured as a counter. 3) LCD display: Liquid Crystal Display which is commonly known as LCD is an Alphanumeric Display that can display Alphabets, Numbers as well as special symbols. Thus LCD is a user friendly Display device which can be used for displaying various messages unlike seven segment display which can display only numbers and some of the alphabets. The only disadvantage of LCD over seven segment is that seven segment has a robust display and can be visualized from a longer distance as compared to LCD. Here we have used 16×2 Alphanumeric Display which means it can display four lines with maximum of 16 characters in one line. 4) Oscillator: The system uses a 12MHz crystal oscillator for clocking. 5) Reset: There is a reset circuitry by which we can restart the system if any error occurs. The circuit also prevents unnecessary clocking when controller is powering up.