We help IT Professionals succeed at work.

Digital LED hack/usage

ne0 asked
I have a digital LED display from a PC (you know the ones that displayed the Mhz right next to the power & reset buttons), but this one is 3 digits and looks like it is serial??? it is connected to a small board via a ribbon cable. On the small board are 3 sets of dip switches (1-8).

On to the point of all this...

I would like to create a small program in which I can use the 3 digit LED to display the CPU temperature. And since it looks to be serially controlled I was wondering if anyone had any pinouts/links/advice.

If I need to increase points I will.

Thanks in Advance,

Watch Question

These things are much less sophisticated than you think.  They are not serially controlled and the 3 signals are:


The DIP switches control what 2 speeds the thing will display.  The Hi/Low signal controls which of these is displayed.



jhance -

Thanks for your reply, I guess the revised question would be...

Is there a way to display the cpu temp on the LED or will I need to purchase the LCD/sensor display that everyone sells?



I do know I will need the sensor in either event but I just dont know if the LED will do for the display...


I'm not saying it's impossible.  But unless you're just looking for a technical challenge and have some time on your hands, I'd suggest one of the CPU temp monitoring kits that has a digital readout included.

I suppose you could fix the thing you have up to display a specific number by controlling the state of the dip switches with an electronic circuit but it may be easier to just start from scratch and build your own unit.  It would be a fairly simple matter to couple a digital readout with a temp sensor and drive the whole mess with a PIC micro controller or a BASIC Stamp device.
You probably don't even have a proper LED display controller on that module, it just lets you set each segment individually. So, if you are asking this because it fits neatly in your case, and you are set for the fun of doing it, then you'll need to buy a 7 sement LED controller chip that converts binary to the correct decimal figures for display, and strip back that display module to it's basics, depending what type you get, you may need one for each figure or you might get one that does two or four figures. So that's your input to the display. Then you'll be needing a simple ADC to sample the sensor and and a timebase circuit to clock the whole thing, sampling every half second should be acceptable I think. You may need some logic to convert from binary to BCD depending on how smart the LED controllers you get are, shift registers etc. You'll also want to put plenty of trimming capacity into the temp circuit so you can callibrate it. (Use iced water as 0 deg c and boiling water as 100 deg c is easiest(99.9 with a decimal I guess)) If you want anything fancy like a floating decimal point, use a PIC. This way will work well for 2 digit plus one decimal Celcius or 3 digit farenheit.

Or temperature displays with remote sensors are cheap these days, look in car accessory stores, gadget stores, even places like Walmart, then you can strip that out of it's case and mount it in your PC, may cost you around 5 bucks instead of around 20 that I think the ready to fit PC kits are.

Or you could look here for ideas....


Road Warrior


Thank you both for the comments/advice.

Although the temp kits were on my list, the Serial LCD Drivebays were the second choice. Not that I don't like the temp kits mind you, but I do enjoy tweaking some things from time to time. I have found a serial LCD for about $35 USD (http://www.crystalfontz.com/cgi-bin/pricing.pl?product=632) and there are already some OCX/DLL controllers for them. In my opinion, it would be best to go ahead a spend a bit more for this but gain much more functionality. Would the both of you agree? Not that there is a right or wrong answer here but I would like to have others opinion.


Glen A.IT Project Manager

Hello Experts / Questioner:

No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:

Paq'd and points split between jhance and roadwarrior (as they did answer the original and revised question)

Please leave any comments here within the next seven days.
EE Cleanup Volunteer

Explore More ContentExplore courses, solutions, and other research materials related to this topic.