Overview
This project features an alarm clock that is easily visible in the bedroom by having a large and bright time display along with a loud and irritating alarm.
Explanation
To create the timebase, an onboard RTC is being featured by the AT90S8535 chip as the external crystal oscillator keeps the timing. The LCD display is the most innovative part of the alarm that gives the date, alarm status, and status for setting the clock. The LCD allows the date to be displayed while maintaining a simple architecture and eliminating confusion when setting the time. A TIP31C triggers the alarm which is a self-contained module and powered by the 12V supply.
Designed for individual addressing of each digit is the LED display which is a multiplexed, common anode display. Each digit contains a unique code for all if the segments. The CPU addresses the display via an 8-bit command. A 7446 chip decodes the actual digit displayed which receives a 4-bit binary coded decimal value and convert it onto a 7-segment display. Every 4 milliseconds, the digits are switched and the software strobes the display, as perceived by human eye.
