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. :eek: )

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 (http://www.st.com/stonline/products/literature/ds/10154/stp16c596.pdf) 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]

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