Here is a project I’m working on since some months now and which is now decent enough to be shown here. The time I spend working on it is inversly proportionnal to the time I spend playing games on console … this explains that :-)
The idea is to have an autonomous multifunction clock that uses two 24x16 leds display … I’ve already talked about those displays : bought on SureElectronics for a very low price (14$), they are really well done, a bit uneven on the luminosity side (between displays), but globally, a very good investment.
On the functionnal side, you have, of course, the time, date but also temperature and relative humidity.

One of my goals was to make a clock that does not look like a breadboard prototype and have a nice design. I’ve bought a plexiglas panel where I’ve cut a front and a back panel. To avoid any kind of screws on the front, I’ve bought a tap kit so I can place the threaded rod directly on the plexiglas without any bumps on the front side …

I’ve never done this before, but it’s pretty simple and the final result is clean and strong. I’ve bought a 40 inches threaded rod that I’ve cut to have my display, the arduino and my board between the front and back panels. The back panel is not yet in place right now, but you can already see what the front panel looks like :

To place the display at a given distance from the panel, I’ve cut small sections on an aluminium tube, so you don’t see the screw and I have even spacing everywhere. I’ve used 4 rods per display to have something sturdy.
On the electronic side :
- an arduino
- a DS1307 to have a good and stable time reference that keeps the time even in case of power outage.
- a DC-SS500 from sure electronics to get temperature and relative humidity.
- an LDR to adjust the display intensity depending of the ambiant light.
- a RFM12B for wireless communication.
The wireless part is not yet done, but there is already some room on the board for it …
The led displays are managed thanks to the library of Miles Burton that you can find here. Very simple to use and it can control up to 4 displays daisy chained. For this project, I’ve used only two displays driven through 4 wires : clock, data, CS1, CS2 … and of course the power. I’ve added some stuff to the library, like ‘giant’ letters as I plan to have several display themes in the future.
Here is the complete schematic (you can click on it to have a higher resolution display) :
As the wiring was pretty straight, I’ve used a small experiment board instead of a dedicated board :

The arduino and my board are placed behind the displays using double sided tape, which also ensure electric insulation.

For the moment, the time is always displayed on the first line of text and on the second line you can see alternatively the day/date, humidity and the temperature. The code is pretty “experimental” right now … but as soon as it will be a bit cleaner, I’ll post it here.
Once the wireless part will be in place, I will link the clock to the other devices in my house. Doing so, I’ll be able to track temperature, humidity and light level on my central pc and also send commands to the clock like :
- synchronise clock to internet
- change display theme
- messages
- …
To be continued…




















