My goal whit this project is to create a wall clock whit big numbers, around 10cm in height, it should be able to set the time, date and hopefully an alarm later on. This far into the project i have managed to achieve most of my goals.
It consists of:
- One atMega168 running at 16Mhz(Just like Arduino)
- 80 red high intensity leds
- A real time clock from NXP Semiconductors (PCF8563)
- A 40x2 LCD display
- Three 74HC595 ics
- A lot of random stuff like resistors, diodes, buttons, wires and other stuff…
Oh before i forget, click on images to get bigger versions
There’s a lot of stuff missing form this photo, all the wiring to the lcs(Currently using 4-bit vertion), buttons for input(Simply Up, down, select and back), I will update this photo once i get my camera back from my girlfriend
Some stuff worth mentioning is the photo resistor located bottom-left, I use it to change the intensity of both the leds and the lcd, i.e if it’s dark in the room the intensity will be reduced a lot.
You may also notice the variable capacitor to the RTC, this is used to fine tune the time, I can get it to run at about ±2 sec a week by some rough adjustments, I’ve heard people got it to run as little as ±1 sec a year. I will most likely make a software solution for this later on… (If you got any ideas please tell me :P).
Here you have the back of the led display, you have the three 595 ics and four fetmos transistors, and some resistors, thats actually all you need at the display.
The led display is using timer2 to create a interrupt at 12800Hz, this enables me to update each number 100 times per second, whit 32 intensity levels. (100 * 32 * 4 = 12800)
Here you have the front of the display in action. I know it looks like the numbers are hardly visible, but trust me, they are really bright. I’ll try to get a better one soon…
Notice the Diecimila standing next to the display for comparison, so now you can pick up your Diecimila and really imagine how big the numbers are.
Hope this have given you some inspiration, I will post the code and some more images later on as the project goes on, right now I’m trying to fix the user interface on the lcd, so that the user may set time, change led intensity parameters, alarm and so on…
If you have got any questions at all please, don’t hesitate to ask!