Guide DigiMeter - LED System Activity Bar-Graph/Chaser - SOFTWARE v1.7

Was going to publish this a few months back, but the software controlled fan bus idea was hot then so I chose the DigiBus over it so here it is at last...

Intro
Whether you actually need the information, or even know what it means or not there is no doubt that system activity information is funky. Your car has about 5 dials in it, your microwave has a little LCD panel, even some fridges have temeprature read outs so why should your PC, a more complicated and usefull machine than all of these things be left out?

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In this guide I'm going to be taking you through building an, upto, 8 LED bargraph to display CPU Load %, Free Memory (RAM) %, HDD Load %, cool effects like Knight Rider chases and much more with next-to-no circuitry which I have self mockingly named the "DigiMeter". Future versions of the software will suport upto 12 LEDs, expect to see that soon.

Guide Contents
Intro - What you're reading now.
Part 1 - Making the Device - Upto 8 LEDS
Part 2 - The Software - Download and User Guide.
Part 3 - Taking it further - upto 12 LEDs.
Part 4 - Taking it further - upto 80 LEDs with the serial port.

To complete the guide you will need...

• Upto 8 LEDs a mix of Green, Yellow and Red works nicely, you can also get special bargraph LED arrays which are convenient.
• Upto 8 1KOhm resistors.
• 1 parallel port plug.
• The provided software.
• Optional stripboard and bits of wire.

Warning (read: Ass-Covering)
Working with ports always carries some risk, as long as you take the advice in the guide and watch out for any accidental shorts you should be fine however I can't test this on all motherboards but I can give you the assurance that on every motherboard I've used this on, and for all the people I've heard from regarding a similar guide I've published elsewhere this device works fine.

Software
Version 1.7
Supports upto 8 LEDs
CPU, HDD, RAM, Knight Rider and Random LED Display Modes.
Tested on Win2000 only, but should work on XP.
No SysTray support until next version.

 

Part 1

The diagram below shows the connections for the device (with 8 LEDs) all connection pins are from the parallel port connector...

The Circuit Diagram​

The digaram looks a little complex but basically all it's saying is that you're hooking up an LED with its own protective resistor to each pin of the parallel port. You can use as little as 1 LED (pretty pointless though), in which case you'd solder it to pin 2 and to ground (pin 25) or as many as 8 LEDs (pins 2 - 9 and 25).

A Selection of Suitable LEDs​

How you connect the LEDs to the port is entierly upto you. For neatness you might want to mount the LEDs to a stripboard or solder the LEDs to the plug individually with 2 fly-out leads each and then mount them in your case. Personally, for speed and because my desk looks like something out of the matrix, i prefer to solder the LEDs directly to the plug, without any enclosures or fancy fixings, this is how I'm going to be taking you through doing it first but will be covering other methods later in the guide when more LEDs are added. When/if you complete this guide feel free to mail me a picture of how you've got it mounted, I'd love to host it and include it in the guide to give people ideas.

First up, you need to prepare your LEDs by attaching the protective resistor. The resistor can be soldered to whichever LED you like but if your mounting it directly to the port you may find the annode or longer leg to be the most suitable. This can be very fiddly especially if, like most of us, you have only 2 hands. I use a non-plastic based tape to position both components on to make sure they don't roll around when trying to sodler them to each other.

A Good Soldering Trick​

Once you've done this for all of the LEDs you want it's tiem to get the port out. Remember that we're soldering the first LED to Pin 2 not Pin 1. You should see the pin numbers in rasied plastic on your connector but in-case they're not there or you just have poor eyesight like me...

The Pins You'll Need to Use​

Now simply solder the longer leg (or the one with the resistor on it in my case) of each LED to each pin bending the shorter leg parallel to the port ready to connect them all to the gorund pin (18)...

Nearly There...​

When you're done you should have something that looks like this, solder the nearest long leg of the LED into pin 25 of the connector and then solder all of the long legs together...

All Done.​

Now all that's left to do is to straghten all the LEDs up so they line up neatly and install the software.

 

Now this is interseting. Looking forward to more...

 

I've seen this advice before for leds running off the PP, but so long as you limit the current it doesn't make any difference to the port safety. And even at 3mA they're brighter than standard leds at 15mA or more.

 

I've never actualy tried it, but that makes sense, i've removed that note from the guide.

 

is it possable to use a usb port i have one inside my comp and i thought it would look more professonial if there wasnt a cord coming out then going back into my comp

 

cant wait for the serial port version, since i dont wanna unplug my beloved digi-bus

ps great guides by the way
amazing everything (pictures, guide, parts, description) thanks for doing this!

 

I'm not going to be coverign a USB version as USB devices are very, very tricky to build and get wroking correctly. However, if you buy a USB to COM port converter and use that to plug into the serial port version of the DigiMeter you should get the desired effect.

 

Serial port version is on a protoboard on my desk so it should only be a couple of weeks 'till the guide and software is done.

 

No matter what I do I cannot get the software to work
When I try to install it it goes up to file 7 of 7 and then says it cannot proceed because files on my system are outdated and it asks if I would like the setup to update the files. I press yes, then OK for reboot. After reboot when I run setup I get the same darn thing. When I try to run DigiKey.exe in DigiKey cabinet file it gives me error that sys'something'.ocx is not properly registered ..........
I run WinME.
Could anybody help out?


PS. Will there be a Linux version of the prog?

 

The software doesn't support WinME, only Win2000 and later. No plans to introduce support for older operating systems, especially since ME, which is even more of nightmare to program for than it is to use.

As for Linux support, I simply don't have the money to buy a decent HHL compiler program that has that degree of portability, although I am aware of several. So don't hold your breath on that front I'm afraid.

Sorry.

 

Is an output of ~3.2v about normal for one pin being used. Im on a laptop if that makes any differnece.

How do you bring the program out of being hidden, rather than starting the program again?

 

Yeah 3.3v is the ideal so 3.2v is about average.

You wait for the next version that hides to the systray

 

He he, I guess I will just enjoy the WinAmp plug-in .
Here is also my setup of DigiMeter v1.0





Hopefully I will make a better version with brigher LEDs (these just suck, especially the green ones) and a better connector.

I also have a couple of questons concerning the behaviour of DigiMeter during boot and before launch of WinAmp plug-in:
-Is it OK for certain LEDs (like PIN num3) to be one all the time?
-Or for LED 7 and 8 be off during boot while others are on?

 

That's a really neat job, I like it.

When your computer boots sometimes it broadcasts information to the ports, you may well find a few LEDs, or even all of them, lit constantly during boot right up until you start the program, this is totally normal and nothing to worry about.

To increase the brightness of the LEDs you could use a lower resistor value for them, the lower you go, the brigther they get, but the more risk to the port. Maybe use an 820 or 750Ohm.

 

Got a bit of a problem with the software, it installs fine, but when i go to run it it brings up the M$ error reporting window, and reinstalling it didnt make any differance.

This is running XP with SP1 and all the current updates. Any ideas?

 

we need a pic of this thing in a case... i need some ideas

 

I compiled this on an XP machine, it's an older version but it should work fine all the same, try this one...

www.mattjasonh.com/_misc/LedBarDriv-WinXP.exe

 

With that latest link i get:

"Data source is either invalid or cannot be found. System message: a required argument is either missing or incorrect"

 

Weird.

Is that right away or do you pick an option and hit Start and Hide first? If you pick an option first, which option is it? Does the Knight Rider thing work?