ARDUINO LED DISPLAY CLOCK PROJECT

This is a project that I have been working on a few months now and I have completed its build very lately.  The main processor used in this project is an Arduino MEGA 2560 which is interfaced with a real time clock called the DS 1307 chip (which gives you the time and date).  

Both Red and Blue LED Displays are driven using NPN transistors ( I used 2N5551 NPN transistors).  The bases of these transistors are connected to the Arduino mega 2560 's digital pins.

The Arduino is also connected to 4 pushbuttons located separately on a small perfboard.  These pushbuttons allow the user to set the alarm time.  The arduino is also connected to a SAMSUNG DVD player front panel via optoisolators hence allowing the arduino to start the dvd player once alarm time is reached.  That basically means that once you have set the alarm time, lets say 6 a.m, the dvd player will play your favourite CD at 6 am and you can stop it by using your DVD remote control or pressing Power button on your DVD player.

I have below some images of the build process which I would like to share with you.

Above is a picture of the displays I used.  The upper 4 displays are 16 segment LED Displays used to display DATE and TIME alternately and light up red... they are also used to show ALARM function. The large displays are 8 in number and light up blue. Whole board measures 40 CM wide.

This 2nd picture shows a close up of the 16 segment LED Displays

The picture above looks complicated and messy...infact the four 16 segment displays are multiplexed  this that means all 4 displays are in parallel but the common anodes of EACH display is driven individually by npn transistors.

In this picture you see tons of npn transistors.. to the base of each npn is a 1 kilo ohm resistor which connects to the arduino pins.  The collector of each transistor is connected to a 150 ohm resistor . 

Ok so in this picture you see the npn transistor board connected to the led displays.. That involved alot of soldering.

I eventually multiplexed the larger blue displays and the displays were so big that they did not fit on the 30cm board I got from eBay so I had to adjust :) Anyway you can see the npn transistor driver board as well as the multiplexed displays in the above picture.  The driver board is identical to that one in use for the 16 segment displays.

You can see a very messy layout for testing purposes of course.  The metal thing you see on the left side of this picture is a heatsink I salvaged from an old ATX power supply.. On this heatsink I placed 2 regulators.  A 5V one (for the 4 segment led displays) and a dedicated 8V one to drive the larger blue displays

Yeah you guessed it I used LM7805 for 5V and LM7508 for 8V. Sweet.

 Ok you can see above the 4 pushbuttons I was talking about earlier on .. their purpose is to set the alarm time. I was using an arduino UNO to test out their functionality before actually mounting them on the arduino MEGA 2560 microcontroller.

Above is another close up view of the pushbutton board.

Looks weird I know. This is a LM 386 audio amplifier chip .. its purpose is to drive an 8 ohm speaker .. It receives audio input from the DVD player I modified.  So basically when alarm time kicks in the dvd player starts playing your CD and the audio is amplified and fed into a speaker by this LM 386 audio amplifier.

I used a gift box as enclosure . I fitted a 4 inch 5W 8ohm speaker in its front and glued a protective metal grill onto it ( I salvaged this grill from an ATX power supply fan).

Above you can see the whole setup finished.  I placed it all in my room to wake me up in the morning :)

You will notice a small square thing attached to the displays (just right to the upper 4 displays) , its a green LED which turns ON when alarm is enabled and goes OFF when alarm time is reached or when alarm is off.

Behind those displays is a cardboard box I have.. I stuffed in all the electronics and you can see the arduino MEGA clearly.

Here is a picture (which probably I should have shown earlier) where you can see the arduino connected via I2C protocol to a greenish pcb.  This greenish pcb is actually the DS1307 clock chip which has a 3V battery on it.. It doesnt lose memory and keeps counting time and date even if arduino is off which is lovely.

I took this on the 09/09/12 .. The green LED is on letting you know that alarm is enabled.

Shows you the time for 5 seconds and then date for 3 seconds alternately.

I set the ALARM time for 6:15 a.m. Yeah I wake up that time every morning.

DVD tray open ready to load you favourite CDs. Whats cool with my DVD player (I'm not sure about other models) is that you can select a song and stop the player.  Once arduino hits play its gonna start from there and play the song you wanted from that CD.

Another view of the whole setup.  I could have used an MP4 player or something to play music but this DVD player was collecting dust so I thought of putting it to use :)

NOTE: - 

(1) I did not use any shift registers or LED driver ICs for this project because it would have complicated everything and the code would have been hard to build.

(2) The library to communicate with the DS 1307 is available at adafruit as a free download.

Thats it guys! I hope you liked my build and I just thought of sharing it with you :)

All comments appreciated.

Below is a collection of higher resolution images of the completed build.

 Below you can find a link of my clock in action.. In this demonstration I set the alarm time to 17-23-00 and the music starts playing when alarm time is reached.

 http://www.youtube.com/watch?v=4pBeb0jBBqM&feature=youtu.be

Thanks alot for visiting my blog!