title: How can Arduino detect the state of an LED?
body: <p>I'm working on a blinking/fading lights program for Arduino. I'm trying to build in some interactivity that's based on LED state and certain switch combinations. Consider: When a button is pressed, if an LED is ON I want to turn it off and if an LED is OFF I want to turn it on.</p>
  
  <p>However, I've not been able to find any information about determining LED state. The closest was <a href="https://stackoverflow.com/questions/4788529/android-getting-status-on-led">this question</a> about Android, but I'm trying to find out if I can do this from the Arduino platform. Does anyone have any practical experience or advice? </p>