Over the weekend I assembled an Alpha Clock Five kit from EvilMadScience.com. I have built several EvilMadScience kits and the polish and attention to detail in the execution is matched only by the imaginativeness of the design. In the interest of full disclosure the evil mad scientist in chief is responsible for my life long happy addition to good coffee...
Those are monstrously huge and bright (though brightness adjustable) alpha numeric LED’s in there. What makes this kit special beyond just being a beautiful project is the serial port it includes and the ability to display text. A display of activity or alarm or temperature or whatever is something that I’ve often built for connection to XTension and once you get used to being able to glance up to see the outside temp or to watch for motion at the front door or whatever you’ll never want to do without. I could run a wired serial port to this, slow speed serial carries just fine over long runs of cat5. This is a TTL level serial port so a level shifter would be necessary at this end. Or with the right usb cable it could be directly connected to the computer, or through a TCP/Serial adaptor over ethernet. But more fun would be wireless via the xBee radios that I recently wrote an XTension driver for.
The clock runs at 5v so the first thing I needed was a 3.3v regulator. I succumb to the urge to work too fast and just built it as 3D solder art rather than use a board. There are dozens of places to order a project kit with a tiny board or you can buy them already made if you dont want to go that far. Both adafruit and sparkfun make xBee breakout boards with the power supply built in too, but I had these blank ones on hand so I used them.
the heat sink is overkill, the radio uses very little power and it barely gets warm to the touch, but in case I wanted to add more devices later to it this gives a nice comfortable amount of overhead. To the clock only 3 extra connections are necessary. 2 for power which run to the regulator and then to the xBee board and one to take serial data back from the xBee to the clock.
I wasn’t sure if I needed to bring out the data ground as well, it worked fine without that here but if you’re in a noisy environment you may need to being that across to the power ground as well. The xBee breakout is equally simple. Power and the tx data pin connected to the rx data pin on the clock.
lots more pins for future expansion. I’m definitely going to add some various color LED’s for signaling various alert or motion states and possibly a PIR motion sensor and a temp sensor as well. But if I tried to do all that on the first pass here it would never get done. This is a very simple breakout board, the pins on the xBee are tiny and while you could solder directly to them you really dont want to do that. The radios need to be programmed by connection to the computer and removed from the socked on this board. If you were to solder them directly it would be impossible to do that.
The xBee and the regulator tacked down with a bit of foam tape to the beautiful acrylic case. And then finally re-assembled. Here I’m holding it so you can see the size of the LED’s as wall as tilting it into the light so you can see the segments:
And that concludes the hardware portion of the project. I’ll get started on part 2 shortly with instructions on setting up the xBee with XTension, tunneling through to the serial ports on it and the scripts to send data to the clock.