Luminance

Overview

The ambient light driver allows a process to read the ambient light from a sensor. Luminance is reported in lux (lx).

Command

• Command number: 0

  Description: Does the driver exist?

  Argument 1: unused

  Argument 2: unused

  Returns: Success if it exists, otherwise NODEVICE

• Command number: 1

  Description: Initiate a sensor reading. When a reading is ready, a callback will be delivered if the process has subscribed.

  Argument 1: unused

  Argument 2: unused

  Returns: BUSY if a reading is already pending, NOMEM if there isn't sufficient grant memory available, or Ok(()) if the sensor reading was initiated successfully.

Subscribe

• Subscribe number: 0

  Description: Subscribe to luminance readings.

  Callback signature: The callback receives a single argument, the luminance in lux (lx).

  Returns: Ok(()) if the subscribe was successful or NOMEM if the driver failed to allocate memory to store the callback.