MMA8652FC datasheet(52/65 Pages) NXP

52 / 65 page

MMA8652FC

Sensors

Freescale Semiconductor, Inc.

•

Four interrupt sources can WAKE the device: Transient, Orientation, Tap, and the Motion/Freefall. One or more of these

functions can be enabled.

—

To WAKE the device, the desired function(s) must be enabled in CTRL_REG4 register and set to WAKE-to-SLEEP

in CTRL_REG3 register.

—

All enabled functions still run in SLEEP mode at the SLEEP ODR.

Only the functions that have been selected for WAKE from SLEEP will actually WAKE the device (as configured in

—

The Auto-WAKE/SLEEP interrupt does not affect the WAKE/SLEEP, nor does the data ready interrupt.

—

Note that the FIFO does not WAKE the device.

—

When set to 1, the FIFO gate (bit 7 in Register 0x2C) will hold the last data in the FIFO, before transitioning to a

different ODR. After the buffer is flushed, it will accept new sample data at the current ODR. See Register 0x2C for

the WAKE-from-SLEEP interrupt enable bit definitions.

•

MMA8652FC has four functions that can be used to keep the sensor from falling asleep: Transient, Orientation, Tap and

Motion/Freefall.

•

Auto-SLEEP bit:

—

If the Auto-SLEEP bit is disabled, then the device can only toggle between STANDBY and WAKE mode.

—

If Auto-SLEEP interrupt is enabled, then transitioning from ACTIVE mode to Auto-SLEEP mode (or vice versa)

generates an interrupt.

6.12

System and control registers

NOTE

Except for STANDBY mode selection, the device must be in STANDBY mode to change any

of the fields within CTRL_REG1 (0x2A).

6.12.1

0x2A: CTRL_REG1 System Control 1 register

CTRL_REG1 register configures the Auto-WAKE sample frequency, output data rate selection, and enables the fast-read mode

and STANDBY/ACTIVE mode selection.

Table 93. 0x2A CTRL_REG1 register (Read/Write)

Back to Register Address Map

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

ASLP_RATE1

ASLP_RATE0

DR2

DR1

DR0

—

F_READ

ACTIVE

Table 94. CTRL_REG1 register

Bit(s)

Field

Description

7–6

ASLP_RATE[1:0]

Configures the Auto-WAKE sample frequency when the device is in SLEEP Mode.

See Table 95.

00 (default)

5–3

DR[2:0]

Data rate selection

See Table 96.

000 (default)

2—

F_READ

Fast-read mode: Data format is limited to single byte

0 Normal mode (default)

1 Fast Read Mode

0ACTIVE

Full-scale selection

0 STANDBY mode (default)

1 ACTIVE mode

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