LED Binary Clock

This is the second revision of my PIC based LED binary clock. The original version was the first PIC project I attempted, it used a PIC16F84A to do both the timekeeping and control the display matrix, unfortunately it didn't keep good enough time and gained about a minute every week.

This second version is based around a PIC16F628A running at 4MHz to control the display, it also uses a DS1307 realtime clock chip to do the timekeeping. Every second the DS1307 sends a pulse to the PIC chip, the PIC then reads the internal time from the DS1307 over the I2C bus and then displays the time in binary on the LED display.

The bottom row of LEDs display the seconds, the middle rows shows the minutes and the top row is for hours. The time displayed in the picture is 01100:010011:011011 or in decimal 12:19:27. The time is in 24 hour format so goes up to 10111:111011:111011 or 23:59:59

The PCB could be made double sided, or as I have done here single sided with 7 wire links soldered in place instead of the top copper layer. It has a 5 volt regulator so could be powered from any 9 - 15 volt DC power supply.

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step 1Parts / Tools

As well as basic PCB making and soldering equipment you will need the following components:1x PIC16F628A & programmer1x DS1307 realtime clock chip1x 32.768kHz watch crystal…

step 2Make PCBs & Program PIC

The first step is to make the PCBs, the PCB layout and schematics for the main clock and the display board are provided in Eagle format. The clock PCB is double sided, but …

step 3Solder bottom components

Solder the 8 resistors, 1 capacitor and the zero ohm link / backup battery as shown to the bottom side of the main clock PCB.

step 4Solder top components

Next solder the through hole components ensuring to orientate the 2 chips, the 2 capacitors and the regulator correctly.

step 5Solder display

For the display you need 17 surface mount LEDs, 6 100 ohm surface mount resistors, 11 zero ohm links and 9 2cm lengths of bell wire. Solder them to the PCB as per the diagr…

step 6Finish

Solder the display PCB to the main clock PCB then all that is left is to connect the power.The PSU needs to be at least 9v DC and need only be rated at about 200mA or so, t…

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