Simple Digital clock using 8051 microcontroller (AT89C51)
A digital clock is one that displays time digitally. The circuit explained here displays time with two ‘minutes’ digits and two ‘seconds’ digits on four seven segment displays. The seven segment and switches are interfaced with 8051 microcontroller AT89C51. This circuit can be used in cars, houses, offices etc.
DescriptionAs soon as the Vcc supply is provided to this circuit, the clock starts from 00:00. The time is displayed on four seven segments (in common anode configuration) by using the concept of multiplexing. This is achieved by using timer interrupt (Timer0) of AT89C51
which is configured to refresh seven segments. The segments are refreshed many times in a second for simultaneous display. The clock runs with a delay of exactly one second. Timer1 has been used to produce a time delay of one second. The data pins (a–h) of all the segments are interconnected and receive signal from port P2 of the microcontroller. The control or enable pins (common anode) are connected to pins 1-4 of port P1 (P1^0 – P1^3).
BC547 is an NPN bi-polar junction transistor. A transistor, stands for transfer of resistance, is commonly used to amplify current. A small current at its base controls a larger current...
Seven Segment Display
A seven segment display is the most basic electronic display device that can display digits from 0-9. They find wide application in devices that display numeric information like digital clocks, radio, microwave ovens...