Energy saving capacitance measuring circuit with contact and position detection

A method for measuring a capacitance used during contact detection and position detection in an inhaler tracking attachment, the method comprising:

• while the inhaler tracking attachment is on battery power, remaining in a first stage deep sleep state;
• switching an inhaler from the first stage deep sleep state to a second stage sleep state for a period of “t0” after a user's finger contacts a metal spray canister;
• initiation of contact detection capacitance measurement to monitor whether a user is in contact with the metal spray canister, which is a component of the inhaler, with a capacitance value of the metal spray canister to determine that the user's finger is contacting the inhaler through the metal spray canister without the user's finger being moved closer to a capacitance sensor;
• in case of contact with the user's finger, switching the capacitance sensor to a third stage awake state, in which a measurement circuit is operated for detecting the contact of the user's finger and for motion tracking of the metal spray canister, the measurement circuit using a switch element with different time intervals, one after the other, such that the measurement circuit is configured to detect the contact of the user's finger based on a first time interval and track the motion of the metal spray canister based on a second time interval, thereby enabling the measurement circuit to operate like two different circuits;
• and
• if movement of the metal spray canister is detected, recording the movement as usage data.