Build Your Own Arcade Controls Forum
Main => Everything Else => Topic started by: Franco B on October 14, 2009, 08:18:15 pm
-
After spending far to much time making something to realise it is no longer needed I thought I would try to recycle it.
How hard would it be to make a clock out of LED segments like [these (http://www.lc-led.com/View/itemNumber/424)] (there is an anode version too if that makes any difference.)
(http://www.lc-led.com/images/displays/digitdisplays/single/whiteSingleDigit.jpg)
I imagine I would have to make up some a PCB for it. I probably have a workable area of about 150mm (6") square by a max depth of 10-15mm.
Could anyone help me or point me in the right direction of such a project?
I have been looking for a slim black and white LED clock but I can't seem to find one, hence why I'm thinking about BMO.
-
No need to make a custom PCB, though you can if you like. This should be quite doable on a piece of perfboard or donut board (I gather the Europeans call this "Veroboard").
All you need is a microcontroller with a stable clock source, some resistors, and maybe some transistors, depending on the drive characteristics of your uC's I/O lines. If you like, you could use a premade development system like an Arduino, but bare microcontrollers (especially AVR) aren't usually too tough to handle. The program is pretty straightforward, but it'll make extensive use of timers, which can be a little difficult for people new to the field of embedded programming.
If you have sufficient I/O to drive each segment individually, just wire them up, use a lookup table to translate BCD time into 7-segment mappings, and output the data on the port. If you don't have enough I/O to hook up each segment individually, what you'd do is drive the common line of each digit off a bank of I/Os and then drive each segment from each digit (wired together) off another bank. You then "scan" the display one digit at a time (turn on each digit for 1/nth of the time where n is the number of digits), thereby reducing the number of I/Os you need.
You can also do this with discrete logic, if you want, but it'll be a lot more wiring, less flexible, and involve a bunch more chips.
-
Thanks for the input MonMotha but thats completely over my skill set.
I was originally looking at deal extreme and saw [this (http://www.dealextreme.com/details.dx/sku.12310)] but it looks to be red LEDs rather than the white shown on the box.
I may just go with something like [this (http://www.dealextreme.com/details.dx/sku.21135)]. Its not white LEDs on black or the reverse but its thin enough and not $40+ from the other clocks I have seen.
-
If you were contemplating making your own PCB, then I would have thought a little MCU programming would be OK, but...
Easiest way would probably be to grab an alarm clock utilizing 7segment LED displays and swap the displays out. You'd probably have to swap some resistors, too, to account for the different voltage drop and current between red/green and white. Finding a suitable "donor" clock may take a few tries.
-
How bout this
http://www.rasmicro.com/projects.htm#CLOCK (http://www.rasmicro.com/projects.htm#CLOCK)
(http://www.rasmicro.com/clock.jpg)
They even provide a kit with the board already done.
Or this
http://cgi.ebay.com/LED-360-7-Segment-Real-Time-Clock,-Date-and-Temp-Kit_W0QQitemZ270467843043QQcmdZViewItem (http://cgi.ebay.com/LED-360-7-Segment-Real-Time-Clock,-Date-and-Temp-Kit_W0QQitemZ270467843043QQcmdZViewItem)
But it's a bit pricy
I just googled "LED Clock project" and waded through a bunch of gunk. There's lots of projects like that out there.
I'm still wanting to dive into a full on Nixie clock project, but real nixies (as opposed to my fake ones) can get quite pricy too.