LED

session.led controls the indicator LED on supported glasses. You give it a color and a blink pattern, and it tells the LED to turn on or off.

src/background/index.ts

import { registerMiniapp } from "@mentra/miniapp/background";

registerMiniapp((session) => {
  session.transcription.on(async () => {
    // Blink green twice when speech comes in.
    await session.led.blink("green", 200, 200, 2);
  });
});

The LED needs glasses with a LIGHT hardware capability. Declare it in your manifest so the miniapp only installs on glasses that have an LED. There’s no runtime permission to request.

Methods

// Turn the LED on with an explicit pattern.
await session.led.turnOn({ color: "blue", ontime: 500, offtime: 500, count: 3 });

// Blink: color, on-ms, off-ms, repeat count.
await session.led.blink("red", 200, 200, 4);

// Solid: hold one color for a duration in ms.
await session.led.solid("white", 2000);

// Off.
await session.led.turnOff();

Method	Signature	What it does
`turnOn`	`turnOn(options?: LedControlOptions)`	Turns the LED on with the given color and pattern.
`turnOff`	`turnOff()`	Turns all LEDs off.
`blink`	`blink(color, ontime, offtime, count)`	Repeats an on/off cycle `count` times. Wraps `turnOn`.
`solid`	`solid(color, duration)`	Holds one color for `duration` ms (one cycle, no off time). Wraps `turnOn`.

LedControlOptions is the shape turnOn accepts:

Field	Type	Default	What it does
`color`	`LedColor`	`"red"`	Which color to light.
`ontime`	`number`	`1000`	On duration per cycle, in ms.
`offtime`	`number`	`0`	Off duration per cycle, in ms.
`count`	`number`	`1`	How many on/off cycles to run.

Colors

LedColor is a fixed set of names. The phone maps each name to the per-device LED index, so the same name can light different physical LEDs across glasses.

Value
`"red"`
`"green"`
`"blue"`
`"orange"`
`"white"`

Every method returns a Promise that resolves once the command is dispatched to the glasses, not when the blink pattern finishes playing. A blink("red", 200, 200, 4) call resolves right after the command goes out, well before the LED has run all four cycles. Don’t await the call as a way to wait for the LED to go dark; if you need timing, track it yourself.

Getting Started

Core Concepts

UI Layer

Display

Audio & Speech

Sensors & Input

Camera

Phone & System

Data

Reference

Methods

Colors

​Methods

​Colors

Methods

Colors