Stylus with attachment detection

A stylus comprising:

• an attachment sensor configured to detect when the stylus is attached to a host device;
• an activity sensor configured to detect when the stylus is moved;
• a communication interface configured to communicate with the host device;
• and
• a controller configured to select one of multiple operating modes for operating the stylus, the operating modes comprising:
• a low-power mode, in which the attachment sensor is actively operated, and the activity sensor and the communication interface are disabled;
• a mid-power mode, in which the attachment sensor and the activity sensor are actively operated, and the communication interface is disabled;
• and
• a high-power mode, in which the attachment sensor, the activity sensor, and the communication interface are actively operated.

A stylus comprising:

• an attachment sensor configured to detect when the stylus is attached to a host device;
• an activity sensor configured to detect when the stylus is moved, the attachment sensor being configured to be either actively operated or disabled in response to an attachment detection by the attachment sensor;
• and
• a communication interface configured to communicate with the host device, the communication interface being configured to be either actively operated in response to an activity detection by the activity sensor or disabled in response to the attachment detection by the attachment sensor.