LED is now so widely used in our life to provide various illumination that we almost forget that LED is essentially a photodiode, that is, it can respond to light. Depending on the emitting wavelength of the LED, when the LED is stricken by photons with similar or shorter wavelengths, a tiny photo-current will be generated. If we can measure this photo-current, we can then measure the photons striking on the LED. Therefore, LED can be used both as a light emitter and as a light detector. This allows us to realize low-cost two-way communication with a single LED.
For details of this please refer to Paul Dietz’s white paper “Very Low-Cost Sensing and Communication Using Bidirectional LEDs” (http://www.merl.com/publications/docs/TR2003-35.pdf).
In this post, we will use an Arduino Nano board and a single LED to demonstrate this idea.
- Arduino Nano board x 1
- Breadboard x…
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