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Learn how to use RGB LEDs on smart glasses to provide visual feedback, notifications, and status indicators in your MentraOS apps. LEDs provide immediate visual feedback to users and can indicate app status, notifications, or recording states. Different smart glasses models have different LED configurations - some have RGB LEDs, others only white LEDs, and some have no LEDs at all.

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📖 Detailed Documentation

For complete method documentation, examples, and advanced usage patterns, see the LED Manager API Reference.

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Quick Start

import { AppServer, AppSession } from "@mentra/sdk";

class LEDApp extends AppServer {
  protected async onSession(session: AppSession, sessionId: string, userId: string): Promise<void> {
    // Always check LED capabilities first
    if (!session.capabilities?.hasLight) {
      session.layouts.showTextWall("No LED support on this device");
      return;
    }

    // Basic LED control
    await session.led.turnOn({ color: 'red', ontime: 2000 });

    // LED patterns
    await session.led.blink('green', 500, 500, 3);
    await session.led.solid('white', 5000);

    // Turn off LEDs
    await session.led.turnOff();
  }
}

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Key Features

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✅ Device Capability Checking

Always check session.capabilities?.hasLight before using LED features to ensure compatibility across different devices.

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✅ Multiple Control Methods

  • Low-level: turnOn(), turnOff() for precise control
  • Patterns: blink(), solid() for common behaviors
  • Capabilities: getCapabilities() to query available LEDs

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✅ Available Colors

  • red, green, blue, orange, white

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✅ Fire-and-Forget Operation

LED commands resolve immediately after sending - no waiting for responses.

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Device Compatibility

DeviceLED SupportLED TypesColors Available
Mentra Live✅ YesRGB + WhiteAll colors
Even Realities G1❌ NoNoneN/A
Vuzix Z100❌ NoNoneN/A

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Common Use Cases

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Notifications

// Success notification
await session.led.blink('green', 500, 500, 2);

// Error notification
await session.led.blink('red', 500, 500, 3);

// Info notification
await session.led.blink('blue', 300, 300, 1);

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Status Indicators

// Recording indicator
await session.led.solid('white', 30000);

// Processing status
await session.led.blink('orange', 200, 200, 10);

// Turn off LEDs
await session.led.turnOff();

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Graceful Fallbacks

if (!session.capabilities?.hasLight) {
  // Use display instead
  session.layouts.showTextWall("📱 Notification");
  // Or audio feedback
  await session.audio.speak("Notification received");
}

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Best Practices

  1. Always check capabilities before using LED features
  2. Use semantic colors (green=success, red=error, blue=info)
  3. Provide fallbacks for devices without LEDs
  4. Don’t overuse - brief, meaningful feedback is best
  5. Combine with other feedback methods when appropriate

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Next Steps