ISM330BX datasheet(5/150 Pages) STMICROELECTRONICS

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2.1

Finite state machine

The ISM330BX can be configured to generate interrupt signals activated by user-defined motion patterns. To do

this, up to eight embedded finite state machines can be programmed independently for motion detection such as

glance gestures, absolute wrist tilt, shake and double-shake detection.

Definition of finite state machine

A state machine is a mathematical abstraction used to design logic connections. It is a behavioral model

composed of a finite number of states and transitions between states, similar to a flow chart in which one can

inspect the way logic runs when certain conditions are met. The state machine begins with a start state, goes to

different states through transitions dependent on the inputs, and can finally end in a specific state (called stop

state). The current state is determined by the past states of the system. The following figure shows a generic

state machine.

Figure 1. Generic state machine

Finite state machine in the ISM330BX

The ISM330BX works as a combo accelerometer-gyroscope sensor, generating acceleration and angular rate

output data. These data, along with analog hub / Qvar sensor data, can be used as input of up to eight programs

in the embedded finite state machine (Figure 2. State machine in the ISM330BX).

All eight finite state machines are independent: each one has its dedicated memory area and it is independently

executed. An interrupt is generated when the end state is reached or when some specific command is performed.

Figure 2. State machine in the ISM330BX

FSM

SIGNAL

CONDITIONING

X = 1..8

ACC [LSB]

GYR [LSB]

ISM330BX

FSM output

Analog hub / Qvar [LSB]

ISM330BX

Embedded low-power features

DS14588 - Rev 2

page 5/150

ISM330BX Datasheet(PDF) 5 Page - STMicroelectronics