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SENSOR DATA CHANGE DECTECTION (SDCD) CIRCUIT

IP.com Disclosure Number: IPCOM000249605D
Publication Date: 2017-Mar-07
Document File: 14 page(s) / 1M

Publishing Venue

The IP.com Prior Art Database

Abstract

Motion sensors, often named inertial units, are accelerometers and gyroscopes capable of sensing either the linear acceleration or the angular rate of the part in motion. Both have circuits to detect motion event such as the free-fall block, the tap or double tap circuit, the transient circuit. The innovation "Sensor Data Change Detection (SDCD) circuit" is an inertial event detection function available to assist host software algorithms in detecting various inertial events such as motion/no-motion (Key fob application), high-g/low-g, free-fall, tap/double tap and transient acceleration events. It incorporates a flexible digital window comparator block that is useful for implementing several different interrupt generation functions. The circuit may be operated in either relative or absolute modes and features user programmable debounce timer, polarity detection, and interrupt generation logic. The innovation allows for support of a wide range of applications.

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SENSOR DATA CHANGE DECTECTION (SDCD) CIRCUIT

Abstract:

Motion sensors, often named inertial units, are accelerometers and gyroscopes capable of

sensing either the linear acceleration or the angular rate of the part in motion. Both have circuits

to detect motion event such as the free-fall block, the tap or double tap circuit, the transient

circuit. The innovation “Sensor Data Change Detection (SDCD) circuit” is an inertial event

detection function available to assist host software algorithms in detecting various inertial events

such as motion/no-motion (Key fob application), high-g/low-g, free-fall, tap/double tap and

transient acceleration events. It incorporates a flexible digital window comparator block that is

useful for implementing several different interrupt generation functions. The circuit may be

operated in either relative or absolute modes and features user programmable debounce timer,

polarity detection, and interrupt generation logic. The innovation allows for support of a wide

range of applications.

Detailed Description:

Motion sensors, often named inertial units, are accelerometers and gyroscopes capable of

sensing either the linear acceleration or the angular rate of the device in motion. Both have

circuits to detect motion events, such as:

- A free-fall block that can be implement in a laptop to warn hard-drives go to safe mode if

a free-fall is detected.

- A tap or double tap circuit used for instance in headphones that do not require a physical

button or switch. Instead, the taps are sensed by accelerometer.

- A transient circuit that detects changes of acceleration or angles to monitor activity or

inactivity. Such transient circuits can be used to save battery lifetime by switching off

the host if the part is in steady state.

The Sensor Data Change Detection (SDCD) circuit is an inertial event detection function

available to assist host software algorithms in detecting various inertial events such as

motion/no-motion (Key fob), high-g/low-g, free-fall, tap/double tap and transient acceleration

events. It incorporates a flexible digital window comparator block that is useful for

implementing several different interrupt generation functions. The circuit may be operated in

either relative or absolute modes, and features user a programmable debounce timer, polarity

detection and interrupt generation logic.

One application of the SDCD is the “passive keyless entry and start” (PKES) system that

unlocks the doors and allows the user to start the car without having to press any button of the

keyfob. This system suffer from two weaknesses: relay attack and power consumption.

The first is a security issue: the low-frequency signal (LF) emitted by the car is amplified by the

thief toward the keyfob. The smartkey is therefore persuaded that the car is close (less than 2

meters) and sends the unlock command to the car. The second weakness regards the power

consumption. A keyfob in the PKES system always listens for the LF from the car,...