Attaching LED's to OI joystick ports?

[tpc]

Hi all,

Has anyone attached LED's to the OI's joystick ports? Page 5 of the OI reference guide seems to indicate that I can attach LED's directly to the joystick port pins, without needing to put a resistor in series. Can anyone confirm that this is true? (I'd like to avoid turning any LED's into DED's (dark emitting diodes) if possible. )

Thanks!
-tpc

[Alan Anderson]

Confirmed. You get no more than 10 milliamps out of the LED driver pins, which will safely light one LED without destroying it.

[tpc]

I tried it this afternoon and it worked like a charm. No DED's.

Thanks!

[ForgottenSalad]

Is there a way to have them controlled by robot feedback? Like how the feedback LED's on the OI are, but plugged into a joystick port pin so we can have them somewhere else on the controller....

[Alan Anderson]

That's exactly what the OI's LED outputs are. They duplicate the state of the pwm and relay LEDs.

[Joe Johnson]

I have not confirmed this but I believe that the OI has an internal LED driver of 10mA (something like the STP16C596 perhaps).

The nice thing about constant current LED drivers is that they provide 10mA regardless of the LED's internal voltage drop, resistance, etc. You can test this out by stacking 2 LED's series. If 2 LED's in series still pull 10mA just like the 1 LED does, then odds are IFI isn't just using an internal resistor to limit current.

Joe J.

[tpc]

Originally Posted by Alan Anderson

That's exactly what the OI's LED outputs are. They duplicate the state of the pwm and relay LEDs.

See http://ifirobotics.com/docs/oi-ref-guide-11-21-05.pdf pp. 7 & 9 for the details.

-tpc