I love analog gauges, toggle switches, and other retro technology, so I had to find something to do with my small collection of antique gauges. The result is my PIC-based analog gauge controller, which takes serial data and displays it on the gauge. Right now it’s displaying CPU usage from my PC.

The guts of the controller are a PIC 16F84A microcontroller and a Dallas MAX233A RS-232 driver chip. I wrote a C# program that samples CPU usage and sends it to the gauge controller as a percentage every 250ms. The microcontroller takes this and converts it to pulses on a digital I/O port. By changing the frequency of the pulses, I can control the analog gauge from a digital output.

The wooden enclosure is just a box from Hobby Lobby that I stained “rich mahogany.”

It will eventually be hooked up to my Mac, so I’ll have to get a USB-serial adapter. If I’m using USB, I’ll see if I can power it via the USB’s 5V line. I also need to get it off that breadboard once everything is settled.

Here is a YouTube video of the gauge in action. I'm having it scroll around Google Earth to generate some load, which makes the needle move.