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  • Digital Clock Using 8051

  • Created: Nov 17, 2014

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The digital clocks are generally used to keep track of the time. It definitely displays the time, which can be easily read by anyone compared to conventional clocks. The device uses SST89E54RDA-40-C-PIE Microcontroller (MCU), a member of the FlashFlex family of 8-bit MCU that comes with 24/40 KByte of on-chip flash EEPROM program memory partitioned into two independent program memory blocks. It is 8051 compatible MCU with embedded SuperFlash memory. In addition, the device uses a seven-segment display to make the time visible for everyone.

As soon as the VCC supply is provided to the 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, which is configured to refresh seven segments. The segments are refreshed a couple of times in a second for simultaneous display. The clock runs with a delay of exactly 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). The number on 4th segment (displaying the unit digit of second) is incremented once in a second as it goes from 0 to 9. The number on 3rd segment is incremented after every 10 seconds from 0 to 5. Thus, seconds are displayed varying from 00 to 59. The digit on the 2nd segment is changed after every 60 seconds from 0 to 9 and so on.

The device can be seen anywhere in the world that may be noticed in the office or at home. This can be integrated to appliances for auxiliary feature and such applications may be observed in FM radios, televisions, ovens that has built in digital clocks.

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I'm looking for a digital clock dia. that can be intergrated into a circuit which will keep track of the power when it goes out and the timer needs to operate to show how long the power has been off and when the power comes back on it does not allow the room power to come back on until I reset with a switch. Its for the central filtration system for my fishroom. If the filter is off to long the it has to be backwashed.

Posted: Sep 05, 2015



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