Flutterby™! : Sensing and Communication with LEDs 2008-11-13 15:19:37.543917+01

Sensing and Communication with LEDs

2008-11-13 15:19:37.543917+01 by Dan Lyke 1 comments

Very Low-Cost Sensing and Communication Using Bidirectional LEDs. By using two pins to drive a LED and current limiting resistor, they can sense how much light the LED is sensing when the LED is off. This was initially used to adjust the LED brightness to ambient light levels:

Compare this to the cost of adding IrDA [7] (about $7) or Bluetooth [8] (more than $10) to a product. Using even a simple mechanical connector can cost several dollars because of the required level-shifting and electrostatic discharge (ESD) protection circuitry. Using an existing LED for communication can also save manufacturing costs because expensive plastic molds for the housing need not be altered to accommodate a dedicated infrared transceiver, antenna or physical connector.

Via Brainwagon.

This is how electric meters do 9600 baud serial communications using two LED's. It's very old school, efficient, cheap for low speed communications. The difference here is doing it with ONE LED. Which is pretty smart.

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