TSL230 Basic Stamp Experiments

The TSL230 is a device that generates a digital clock source that changes in direct proportion to the amount of light incident on it. The shortest description of its use is this: Light comes into the chip and strikes a scalable photo detector array, and that array produces a current that drives a current-to-frequency converter. The more light that hits it, the higher the current, and the higher the output frequency. The result is an eight-pin chip, smaller than a dime, which can give us a clock source whose frequency represents a specific intensity of light.

Photocells and photo-resistors do a similar task. Light incident on those devices affects the voltage and resistance across their leads. And we might be able to get away with measuring resistance on the Stamp with the command RCTIME, but the result would be an ever varying time base, subject to moisture, lead length, temperature, and a myriad of other factors. And without external circuitry such as a voltage controlled oscillator, or an analog to digital converter, we'd have quite a time acquiring accurate data with the Stamp. The TSL230 takes care of everything for you, and can do so in only one I/O line of the Basic Stamp from Parallax, Inc. (We use more for the initial setup, but the four extra wires could easily be hardwired to logic levels high or low).