The Super VMW CPU Meter


This is a project I've been occasionally working on since 1998. I have had a simple 8-LED CPU meter for years. Since my time as an undergrad I've been planning a fancier, alphanumeric replacement. Thirteen years later, after a few abandoned attempts, I finally have a finished version.


The meter has six 14-segment Alphanumeric digits, two 10-segment bar graphs, 12 additional red LEDs, and 6 colorful LEDs (ROYGBV).

The display is driven by 4 SAA1064 LED driver chips hanging off of an i2c bus. Currently this is driven by Linux from the parallel port; I hope to create a USB version at some point.

The hardware to make this ends up costing ~$100 or so, although that involves buying some of the parts in bulk and already having some of the extra tools.

The geda source for the circuit boards is included with the source code download.

Parts list and build instructions: svmw_meter_build.pdf


Source for the examples, documentation, and PCB designs: You can also download the git tree from here via:
  git clone git://
You can run the examples even without the hardware. The source code will build versions that display ANSI color ASCII art output. This allows testing of display routines w/o having hardware available.

Featured examples

Movie of Meter in Action

Original Meter Running Demos:

Prototype USB Meter Running Space Battle Simulator:

Construction Pictures

Prototype USB version, with the USB circuitry on a perf board where the parallel port usually would be (again, apologies for fuzziness):

Proof of concept of USB support, showing "HI". An attiny on the breadboard is acting as the usb->i2c bridge:

Finished parallel-port meter running CPU-meter software with linux-kernel "make -j1". It's a dual core machine, so total CPU is 50% with one CPU maxed out and one idle.

Finished meter running clock software. Day of the week is indicated by color LEDs (it's Sunday so none lit). 32-bit UNIX time is shown around the edge via bargraphs. Occasionally day/month/year is shown on display. Both red/green and green/red display options shown.

The finished project, cover removed (I apologize for the fuzzy pictures):

A view showing the various hacks needed to make it work. Most were due to me not realizing that most chips/connectors overhang the sockets on either side, necessitating lofting of some of the sockets.

You can see pictures of the display PCB and logic PCB.

Here's some pictures of the finished prototype, running the "spin" demo:

Here's an earlier picture of the hardware with only two digits implemented:

A notebook page showing preliminary design.

Here's the 14-segment ASCII font I came up with. Each charachter is unique so in theory you could dump C-code through it.

Older Attempts

Future Work


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A VMW Hardware Production -- by Vince Weaver -- vince _at_
Last Updated 24 May 2011