January 2005, Issue 174

Light-to-Frequency Conversion (Part 2)
Pulse and Oxygen Content

FINISHED?

This project has potential. You could build a stand-alone sensor in which a processor is mounted along with the LEDs, the TSL230R light-to-frequency converter, and a piezo beeper to give audible feedback concerning the beats per minute rate. With an on-board 3-V battery, this low-power device could become a metronome for pointing out radical problems without being tied to bulky medical equipment. By adding a small LCD, both beats per minute and O2 data can be determined with a highly portable system.

This project is a handy way to experiment with the TSL230R sensor. Although I didn’t get around to squashing the code into an eight-pin microcontroller, you can easily put the stand-alone version with a piezo output in that device. Based on the jungle of wires and tubes I saw in Joshua’s recovery room, I bet future medical gizmos will incorporate wireless networking.

TAOS has unique parts that are good alternatives to analog optical sensors. Their digital output provides a simple interface to all microcontrollers without the need for potentially noisy analog signal conditioning and ADCs external or internal to the microcontroller. Check out TAOS’s array of optical products the next time you have a design that requires light detection.