Specifications

Chapter 6 - Samples

Optocoupler on an output line

An Optocoupler can be used to separate the output signal of a microcontroller from an output

device. This may be needed for high voltage separation or current amplification. The output of

some microcontrollers is limited to 25mA. The optocoupler will take the low-current signal from

the microcontroller and it's output transistor will drive a LED or relay, as shown below:

Output line optocoupler example

The program for this example is simple. By delivering a logic '1' to the fourth pin of port A, the

LED will be turned on and the transistor will be activated in the optocoupler. Any device connected

to the output of the optocoupler will be activated. The transistor current-limit is about 250mA.

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