Tutorial Microcontroller MCS-51 ATMEL ISP

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AT89C4051 as RTC

Ajay Bhargav, ajay_bhargav@hotmail.com


It is a digital clock which make use of AT89C4051 to work as a Real time clock.

Figure 1: Circuit Diagram for Digital Clock


Figure 1 shows the circuit diagram for the digital clock. Port 1 of the controller (AT89C4051) is used as the data lines for the LCD (starting from pin 7- pin14 of LCD). Here I am using a 16 x 2 lines LCD display. The first line shows "DAY" and "DATE" in the second line. Time format "TIME" is 12:00 with am/pm.

Port 3 is used for the clock setting and it also provides the necessary control signals for the LCD. As shown in the diagram, switch 3 will be used to select the parameters which need to be changed, switch 1 and 2, are used to increase or decrease the selected parameter value.

When the power supply is switched on it will give you the default date and time, but later you can change it to the desired value.

The source code for the project was written in C-language, and compiled using Keil C compiler. You can download the c-code, schematic, and if you don't have a cross compiler then you can directly burn the HEX file on to your chip easily, clock.zip ( C clock file and clock circuit schematic )

NOTE: If you think that there is a problem in the availability of 89C4051, then you can also use AT89C51/AT89C52, make sure that you are using the same port for LCD and switches which are there in the C-file or in the schematic.

The schematic contains the power supply module also, which is not shown in the figure above. For any help regarding the project please mail me anytime.

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