Toggle a pin when extruding (Marlin)

I'm working with a modified makerbot using printrboard rev D running Lincomatic's adapted marlin. However, my question should be applicable to all marlin systems. I want to turn another device on when extruding, and off when not extruding by toggling one of the extra pins on the expansion ports. (let's say I want to control an extrusion indicator led, but it could be any external device) Seems pretty simple, but I'm having trouble finding a logical place to do this in marlin. Where is the best place where a distinction between starting and stopping extrusion could be easily made where I could add code to toggle the pin?

Probably where enable pin is changed for e axis? I leave my extruder enabled all the time during a print, but the code exists to turn off motors to extruder and to turn motors on to extruder.

Probably in planner.h, or stepper.h. I'm not sure where the code is currently, as I am not at home and cannot look at the files, but you can do a search in the file folder for text and the files that have 'enable' word in them likely deal with stepper enable.

Edited 1 time(s). Last edit at 06/18/2013 08:03PM by jamesdanielv.