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So, which version of Arduino did you modify, exactly? I just installed v1.6.8 and WInterrupts.c is considerably different than your modified one. I suspect Arduino itself has been updated with important changes since your post. This means that using your WInterrupts.c could be out of sync and break something else for Arduino. So... what did you modify, exactly? That way, folks here will be armed with the info needed to keep their latest Arduino up to date by changing WInterrupts.c for HIDJoy, and not downgrade things and get out of sync.
It looks like all I need to do in Arduino v1.6.8 (or v1.6.x?) WInterrupts.c is replace this: IMPLEMENT_ISR(INT0_vect, EXTERNAL_INT_0)with this: #ifndef INT0_vect IMPLEMENT_ISR(INT0_vect, EXTERNAL_INT_0) #endifBasically, wrap the INT0_vect initialization in a compiler if statement. Does that look right? Anything else? BTW, Arduino does let you _compile_ without this modification, but I'm not sure if it runs right on the device (haven't tried it). Also, I don't see where RCTrainer refers to INT0_vect, but maybe I'm not good at my string searches through the files.