Simple Clock

September 2019   Bianchini-Love

Project Documents

Simple clock is a just as the name implies: a minimalistic clock that has one button and one potentiometer and no extraneous features. The button is used to set the time; pressing and holding the button speeds up the seconds by a factor of 250 and a prolonged press of the button (after pressing the button for roughly 6 seconds real time) puts the clock into super fast mode, with one hour ticking by approximately every second. The potentiometer controls the brightness of the entire display, including the colons. This project uses the display and part of the code from Henry's final project from 6.115 - Microcomputer Project Laboratory. After re-discovering the breadboarded 7-segments displays, the project was resurrected and behold SIMPLE CLOCK!!!!

Figure 1:  Close-up of Simple Clock in the shadow box frame.

Overview

The brain of Simple Clock is an AT89S52, a microcontroller that is compatible with the Intel MCS-51 family.  The benefit of using this microcontroller is that it can be programed in circuit using an Arduino; no need for a specialty programming device.  This was extremely useful for development purposes.  To keep time, the AT89S52 uses a 12MHz crystal which is subdivided inside the microcontroller.  Hours, minutes, and seconds are displayed on large, one inch 7-segment LED displays that are easy to read from any angle.   The clock lives up to its name; there are no alarms, or extraneous features; it is purely a time keeping device, with only 12hour mode available and no AM/PM indication.  The simplicity was desired and made it possible to complete the clock (note the that the 7-segment LEDs and their respective drivers were already wired) in one day.