I'm working on an interface to control a variable-brightness LED. The obvious choice to me is to use something like a slider. The LED can be adjusted within the GUI or externally, so I need to allow the user to change to setting, and also display the current setting, so it seems like a slider is not the ideal in that regard.
What are some approaches that have been used to display input and output at the same time in a slider format? What would be a good way of approaching this problem?