Today I did a little test using analogue input for my LED. I build my third RBBB today and wanted to take the LED output a little further. For my breathing device it will have to respond to the analogue input of breathing. So I emulated that with a light sensor. Covering the sensor less or more changed the brightness of the LED. For a start it was fine, but with breathing the LED will have to go from no light to very much light to give proper feedback on the respiration pattern.