How does this robot have addressable LEDs still running when disabled?

[CronusWorks]

1076 electrical mentor here.

The LEDs are driven by a Pololu A-Star 32U4 (more or less an Arduino Leonardo). This is connected to the serial output on the RoboRIO's MXP.

When powered on, it runs the idle animation and waits for serial data. Once it receives data, it does a boot-up animation and then the main one (stripes that move back and forth with the motors they're next to). If no data is received for 750 milliseconds, it does a shutdown animation and then back to the idle.

The RoboRIO sends a single byte every time it runs through the control loop during autonomous and teleop to tell it which motors are moving which direction. We aren't actually telling it to run the idle animation, it just falls back to it when there's no data.

If anyone's curious, we're powering the LEDs with one of these http://www.mini-box.com/DCDC-USB.
We initially bought it for our Jetson TK1, but that didn't end up making it onto the robot this year.

[Frank Neuperger]

Is it legal just to use an NPN transistor to drive the LED strip? drive the transistor from the DIO on the roborio. power form a fused output on PDB.

I don't see anything in rule 44 forbidding this.

Wires would have to be the appropriate gauge for the fuse on power distribution board.

[Team118Joseph]

The SPI bus on the Roborio can still run while disabled. This can be helpful for debugging issues on the robot while disabled on the field, providing feedback about connection issues and calibration details using the LEDs.

[Mark McLeod]

Originally Posted by Frank Neuperger

Is it legal just to use an NPN transistor to drive the LED strip? drive the transistor from the DIO on the roborio. power form a fused output on PDB.

That's what our robot uses.
Just remember to design your custom circuit for 3.3v from the DIO signal.