Picture of 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 1: Parts / Tools

As well as basic PCB making and soldering equipment you will need the following components:

1x PIC16F628A & programmer
1x DS1307 realtime clock chip
1x 32.768kHz watch crystal
3x BC548 (or similar) transistor
2x PTM pushbuttons
1x 78L05 regulator
2x 220uF electrolytic capacitors
17x Surface mount LEDs
1x DC power jack socket
5x 4.7K surface mount resistors
8x 100 ohm surface mount resistors
1x 2k surface mount resistor
12x zero ohm links (Or 11 zero ohm links and CR2016 backup battery)
1x 100nF surface mount capacitor
50cm single stranded bell wire
1x 9v - 15v DC power supply with DC jack

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EzEe2 years ago
Hello Eleven I suppose its a very old thread bu I liked your clock.
I am working on my own version in light of your clock. Can you shed some light on how your Hrs and Mins setting buttons work. How have you wrote the code. Just some clarification of the concept would help.

botronics3 years ago
I would like to make this small enough to make a pocket watch out of it. To save power, is there a way to have the leds come on only when needed? Maybe this would work: If power to the pic only is left off, will the correct time show when the pic is turned on for a moment? While all the time the DS1703 is always running in the background to keep the time base.
shuttleu935 years ago
could you please draw up the schematic so it is easier to read please?
ElevenOf9 (author)  shuttleu935 years ago

The schematic files were available in the zip files, but I have also uploaded them now as images to the instuctable for easier viewing.
.sch file isn't working with my software: ExpressSCH .

I what soft was made this .sch?
ElevenOf9 (author)  dava_23 years ago
Hi, it was made in Eagle
Thank you, works now!
dava_23 years ago
Anyone made PCB without those SMD components?

If you are interested, I can make it..
pravardhan5 years ago
Nice Idea. But, why are you using PIC16F628A instead of PIC16F84a?

There is no schematic in jpeg format in the ZIP files and the one given in the site does not have the values of the components....!

And, is there any converter that can convert from Binary to Decimal? May be something like ADC (Analog to Digital Converter)???

the fact that the time reads out in binary is the desired affect, if this is not to your tast then you could easily reprogram the chip to output the time to the serial port of a LCD display. but if you where capable of doing this then you would probably be content with learning how to read the time in binary form to confuse your friends. 2 + 2 = 10 in base four, I'm fine!
hi how long did it take to build it
ElevenOf9 (author)  sebborn3 years ago
Hi, to actually assemble it only took a few hours.
also, this project is pure genius!
ElevenOf9 (author)  pravardhan5 years ago

The PIC16F84A does not have an internal oscillator so would need extra components compared to the PIC16F628A to get it to work, the 16F628A is also cheaper than the 16F84A.

The compnents are listed in step 1 and steps 3, 4 & 5 show where they all go, but I'll try to get an updated schematic up in the next few days, I've only recently started using Eagle so I'm still finding my way around it.

You could impliment circuitry so convert the output from binary to decimal, but that kind of defeats the object I had in mind. An ADC would not help in this respect, you would need a binary to decimal decoder. It would be much easier to write an alternate program for the PIC to get it to output the time in the format you want instead though.
sebborn3 years ago
moapz4 years ago
thanks eleven.
i create  it again, with new parts. the new one,work well.
thank you

moapz4 years ago
hey. thank you for this.
it's finished, and work well :) but after 2day , it's off :( and i don't know why it is not work !
all LEDz is off!
i check voltages and it's good but i don't know why not work !
i changed all parts and create it again but not work !
ElevenOf9 (author)  moapz4 years ago
Hmm, that's a tricky one, if it worked for 2 days then I don't see why it would suddenly  stop then. The first one I made I put the voltage regularor in backwards but that only worked for a few seconds before it burnt out. If you measure the voltage accross pins 5 & 14 on the PIC chip you should have 5 volts.

You asked in one of your other questions if you could use bell wire instead of the zero ohm links on the display PCB, if you did thta are you sure the wire isn't shorting out on the other tracks on the PCB? 

Try replacing the "1 second" LED (bottom right) to see if that makes any difference.

Try replacing the 3 transistors.

Th eone I made has been happily running for over a year now so I'm not sure what has gone wrong with yours, the only other thing I can think of is that there is a break in one of the tracks on the PCB, or a blob of solder is shorting something out.
dimjan5 years ago
nice job
good !!!!!!
moapz5 years ago
can I use bell wire instead of zero ohm ?
why zero ohm ?
ElevenOf9 (author)  moapz5 years ago
Hi, yes you can use bell wire instead if you want, just make sure you don't short out the track that runs between the 2 contacts for each link. I used zero ohm links for 2 reasons, I think in this application they look neater than wire links and more importantly I have about 200 of them that I need to use up on something.
Could you clarify the concept of operation, i don't understand, how you are able to individually address each led from the pic, im assuming that you dont need to, and with this combination at any given time, you can turn on the required combination of led's to display the time.

could you explain this a little ?
ElevenOf9 (author)  lachlanmiller5 years ago

The LEDs are multiplexed, so at any given time only 1 row is illumiated, the PIC is constantly turning each row on and off so fast that it looks as though all 3 rows are illuminated at the same time. All 17 LEDs are controlled by 6 data lines and 3 address lines.

First of all the PIC loads the data for the seconds into PORTB, it then sets the address line for the seconds row high (turning on the LEDs) after a very brief pause it sets the address line for the seconds row low (turning off the LEDs). Then it loads the data for the minutes row into PORTB, turns on the minutes address line, paues, then turns it off again. The hours are displayed in the same way, then the whole process starts again.

A good visual example of how to multiplex LEDs can be found here:

I hope this helps.
hey use the atmega128 you can make it do some pretty nifty tricks when tied to the rs232r serial converter chip ! 
& bookmarked.
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