Microcontroller-Based Clock Using DS1307
Digital wall clocks, table clocks and desk clocks with pointer or LCD display are readily available in the market. Here we present a clock that can be built in a small budget using AT89C2051 microcontroller. Additional feature of the clock is that the time display is visible even in the dark. Circuit description Fig. 1 shows the circuit of the microcontroller-based clock. It comprises microcontroller AT89C2051 (IC1), inverting buffer ULN2003 (IC2), real-time clock (RTC) DS1307 (IC3), regulator 7805 (IC4), non-inverting source driver UDN2982 (IC5) and a few discrete components. Microcontoller AT89C2051 is the heart of the clock. It is an 8-bit microcontroller with 2kB Flash programmable and erasable read-only memory (PEROM), 128 bytes of RAM, 15 input/output (I/O) lines, two 16-bit timers/counters, a five-vector two-level interrupt architecture, a full-duplex serial port, a precision analogue comparator, on-chip oscillator and clock circuitry. Port pins P1.7 down through P1.1 of the mic