ELECTROCARIAN

RTC INTERFACING 9.1 INTRODUCTION The real time clock is most widely device that provides accurate time and date for many applications. RTC chip has the capability of providing time components of hour, minute and second, in addition to date/calendar components of year, month, and day. The RTC chip uses an internal battery, which keeps the time and date even when power is off. Although some 8051 microcontrollers come with RTC embedded into the chip, we have to interface vast majority of them external to the 8051 chip. One of most widely used RTC chip is DS1307 from Dallas Semiconductor/Maxim Corp. This RTC chip has specific features of Two-wire Serial Interface. The DS1307 Serial Real-Time Clock is a low-power; full binary-coded decimal (BCD) clock/calendar plus 56 bytes of NV SRAM. Address and data are transferred serially via a 2-wire, bi-directional bus. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. The end of the month date is a

LCD INTERFACING 8.1 LCD Features LCD stands for Liquid Crystal Display are the most widely used output devices for 89c51 type microcontroller. Nowadays LCDs is finding widespread use compared to LEDs and 7-segment. This is due to following specific features: 1. The declining prices of LCDs make its use cost-effective. 2. The ability to display numbers, characters and graphics. This is contrast to LEDs, which has limited to numbers and few characters. Incorporation of a refreshing controller into LCD, thereby relieving the CPU of the task of refreshing the LCD. In contrast, the LED must be refreshed by the CPU to keep displaying data. 3. Ease of programming for characters and graphics. 8.2   LCD Pin Descriptions The LCD which we have used in our TRAINER KIT is discussed in this section. It has 14 pins. Figure shows the position of various pins. 1. VCC, VSS, and VEE While VCC and VSS provide +5V and gro