For a special topics electronics course I took during my freshman year at RIT, I make a lightmeter using a BASIC STAMP microcontroller and a few other parts.

It uses a BASIC STAMP for processing and a light-to-frequency converter to sample irradiance.

Here is a presentation that outlines the project.

The code to make it display the light values can be downloaded below. Admittedly, it’s mostly a mash-up of various Parallax demo files. Feel free to customize it as you see fit.

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Functionally it leaves much room for improvement. The buttons on the LCD could be utilized, f/stop or exposure time (or eV) values could be indicated. I am putting this on the web in the hope that someone will pick up the ball and build a better light meter.