Can I use an input from the OI to send information to control the robot, as well as having that same input drive a transitor to light an LED?
With the specific exception of the USB Chicklet, connecting any powered circuitry to the joystick port is forbidden.
Using a double-pole switch, with one pole going to the OI port and the other to your LED circuitry might be permitted. Check Q&A to make sure.
I am not sure I agree with this statement 100%, if you are saying that any item that requires power is not allowed. According to the rule:
<R83> All equipment connected to the joystick ports of the Operator Interface must be powered solely through the power available through the port. External power sources of any type are not permitted on any equipment connected to the joystick ports. Portable computing devices can not be connected to joystick input ports on the Operator Interface. Powerpassive devices (e.g. joysticks that draw their power solely through the Operator Interface joystick port) are permitted.
I read this to mean that, as long as you draw power from the OI, and =NOT= through an external power source (with the exception of the Chicklet), then you can use it. The OI joystick ports do, in fact, supply +5V, through LED outputs and the +5V Aux port. I read this rule to mean that you can power anything through this port, as long as it aligns with the above statements (i.e. portable computing device).
Have I interpreted this incorrectly?