# Binary Clock Schematic Circuit Diagram

This clock displays the time in binary using discrete LEDs. The use of Flowcode [1] makes it very easy to program the PIC controller in this project. The circuit is very simple and can be constructed with individual parts on a piece of experimenter’s board or using the relevant E-blocks modules: EB006 (1x PIC Multi-programmer), EB004 (3x LEDs), EB005 (1x LCD) en EB007 (1x switches). The firmware, which can be downloaded from the website for this article [2], determines how this circuit functions. Port B drives six LEDs for indicating the seconds, Port C drives six LEDs for indicating the minutes and port D takes care of driving the five LEDs for indicating the hours. Two pushbuttons on port E let you adjust the time (S1 for the hours and S2 for the minutes). This leaves port A available to drive the LCD display in 4-bit mode. For completeness, this display also shows the time, as well as the day of the week (1 to 7).

S3 is used to reset the processor, which also results in the seconds being set to zero. The current through the (white) LEDs is about 11 mA, which means that the total current supplied by the PIC will always remain below 200 mA. The LEDs project their light onto white opaque glass, which is covered by a transparent sheet with numbers printed on it. On top of this is a clear pane of glass. The LEDs are mounted in a frame with holes, so they will always remain neatly in place.

For the power supply, you can use a plugtop adapter with a stabilized 5 volt/400 mA output. Goldcap C4 is optional and can be added if you want to stop the circuit from losing the time when there is a brief power cut. At midnight the time jumps forwards by 54 seconds in order to keep the exact time (if required, this can be changed in the Flowcode). This is necessary because increasing or decreasing the internal counter is either just too much or too little to keep perfect time. In the photo the time is: 16+4+1= 21 hours (bottom row) 32+16+8+1=57 minutes (middle row) and 32+16+4+1=53 seconds (top row). With the circuit housed in a suitable enclosure, you end up with a nice looking designer clock, which is guaranteed to be noticed by any visitors!

[1] www.matrixmultimedia.com

[2] www.elektor.com/090187

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