This article is an improved version of LCD based clock using RTC DS12C887 and 8051 microcontroller (AT89C51) using update interrupt. DS12C887 has two modes of operation i.e., 12 hour and 24 hour mode. In our earlier articles we explained how to use 24 hour mode. This article explores how we can use the 12 hour mode of RTC. This is done by making a clock using RTC and 8051 microcontroller (AT89C51) with 12 hour mode operation. The clock time is displayed on a 16×2 LCD interface. The free source code for the program is available in C.Port P2 is used as data port for LCD while port P0 of the microcontroller AT89C51 is used as data port for the RTC DS12C887. The pins P1^0 – P1^7 of the microcontroller are configured as reset, rs, rw, e, dig_hr1, dig_min1, start, setmode, am_pm pins respectively. 

 DS12C887 is a real time clock (RTC) IC from Dallas Semiconductors. The RTCs provide precise time and date information. This article explains the making of a [[wysiwyg_imageupload::]]digital clock with alarm setting functionalities. RTC has been interfaced with AT89C51 to perform desired operations. This project is an improvement over Digital clock using RTC DS12C887 and 8051 microcontroller (AT89C51) with time set and has the alarm setting function also. The alarm setting function allows user to set the alarm. The clock time is displayed on the LCD.  The free source code for the program is available in C.The circuit for interfacing the RTC and 16×2 LCD with the microcontroller 8051 is shown in the circuit diagram. Port P2 is set as data port for LCD to send the data on the LCD while port P0 is set as data port for the RTC DS12C887.  

Real time clock (RTC) is widely used in many application to provide accurate time. This article explains the making of a simple digital clock using RTC DS 12C887 and 8051 microcontroller (AT89C51). The output is displayed on an LCD. This clock also has a provision of setting time at any instant. The clock uses the concept of our earlier articles of interfacing RTC DS12C887 with microcontroller. The clock described here uses the method of polling for running. For further details on interfacing RTC DS12C887 with AT89C51 using polling, refer RTC interfacing.  The free source code for the program is available in C. The circuit diagram shows the connection of RTC with the microcontroller. Port P2 is used as data port for LCD; port P0 of the microcontroller is used as data port of RTCDS12C887.  The pins P1^0, P1^1, P1^2, P1^3, P1^4, P1^5, P1^6 of controller AT89C51 are configured as reset, rs, rw, e, dig_hr1, dig_min1, start pins respectively. 

 The purpose of an RTC or a real time clock is to provide precise time and date which can be used for various applications. RTC is an electronic device in the form [[wysiwyg_imageupload::]]of an Integrated Chip (IC) available in various packaging options. It is powered by an internal lithium battery. As a result of which even if the power of the system is turned off, the RTC clock keeps running. They play a very important role in the real time systems like digital clock, attendance system, digital camera etc. The article presented here shows how RTC can be interfaced with the microcontroller AT89C51. It explores the basic operation of accessing the internal registers and extracting time from the RTC. The time is displayed on the hyper terminal using serial communication. The RTC used here is DS 12C887. 89C51 microcontroller is a very commonly used controller from the family of 8051 series of microcontroller.