LED Lighting (5V, using strap‐on power) - quasics/quasics-frc-sw-2015 GitHub Wiki

Using a USB power bank is a great way to power LED strips without taxing the robot's main electrical system. This is especially useful for high-density strips or decorative "underglow."

[!IMPORTANT] THE COMMON GROUND RULE: Because the USB pack is a separate battery, you MUST connect the Ground (-) wire from the USB pack to the Ground (-) wire of the RoboRIO PWM port. If you don't, the LEDs will flicker, strobe, or not turn on at all.

🛠️ Required Components

  • LED Strip: 5V Addressable (WS2812B).
  • Power Source: USB Power Bank (Look for one rated for 2.1A or 2.4A output).
  • USB Cable: A "sacrificial" USB-A cable (to cut open) or a USB breakout board.
  • Controller: RoboRIO 2.0.

🔌 Wiring Procedure

1. The USB Breakout

  1. Take your USB cable and cut off the "device" end (the micro-USB or USB-C end).
  2. Strip the outer casing to find the four wires inside.
    • Red: 5V Power (+)
    • Black: Ground (-)
    • Green/White: Data (We don't need these; cut them short and tape them off).

2. Powering the Strip

  1. Connect the USB Red (5V) wire to the LED strip's 5V / V+ wire.
  2. Connect the USB Black (GND) wire to the LED strip's GND wire.

3. Logic & Common Ground

  1. The Signal: Connect the White/Yellow PWM wire from the RoboRIO to the DI (Data In) on the strip.
  2. The Shared Ground: Take the Black PWM wire from the RoboRIO and splice it into the same GND connection where the USB Black wire meets the LED strip.
    • This links the USB battery's ground to the RoboRIO's ground, allowing the signal to flow correctly.
  3. The Red PWM Wire: As always, cut the Red wire on the PWM cable. The USB pack is handling the power!

📌 Wiring Reference Table

LED Strip Wire Connects To Role
5V (Red) USB Cable Red Main Power.
GND (Black) USB Black AND PWM Black Common Ground (Crucial!).
Data (DI) RoboRIO PWM Signal (White) Data Instructions.

✅ Pre-Flight Checklist

  • Mounting: Is the power bank secured with more than just Velcro? (We don't want a 1lb battery flying into the intake during a collision!)
  • Current Limit: Is the power bank rated for enough Amps for your LED count? (2.4A is usually enough for ~40 LEDs).
  • Charging: Did you remember to charge the pack? (Add "Charge LED Pack" to your pit crew's checklist!)
  • Common Ground: Is the RoboRIO PWM black wire connected to the USB ground?