MMA8452Q

Sensors

38

Freescale Semiconductor, Inc.

0x2B: CTRL_REG2 System Control 2 Register

ST bit activates the self-test function. When ST is set, X, Y, and Z outputs will shift. RST bit is used to activate the software reset.

The reset mechanism can be enabled in STANDBY and ACTIVE mode.

When the reset bit is enabled, all registers are rest and are loaded with default values. Writing ‘1’ to the RST bit immediately

resets the device, no matter whether it is in ACTIVE/WAKE, ACTIVE/SLEEP, or STANDBY mode.

At the end of the boot process the RST bit is deasserted to 0. Reading this bit will return a value of zero.

The (S)MODS[1:0] bits select which Oversampling mode is to be used shown in Table 58. The Oversampling modes are

available in both WAKE Mode MOD[1:0] and also in the SLEEP Mode SMOD[1:0].

0x2B: CTRL_REG2 Register (Read/Write)

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

ST

RST

0

SMODS1

SMODS0

SLPE

MODS1

MODS0

Table 57. CTRL_REG2 Description

ST

Self-Test Enable. Default value: 0.

0: Self-Test disabled; 1: Self-Test enabled

RST

Software Reset. Default value: 0.

0: Device reset disabled; 1: Device reset enabled.

SMODS[1:0]

SLEEP mode power scheme selection. Default value: 00.

See Table 58 and Table 59

SLPE

Auto-SLEEP enable. Default value: 0.

0: Auto-SLEEP is not enabled;

1: Auto-SLEEP is enabled.

MODS[1:0]

ACTIVE mode power scheme selection. Default value: 00.

See Table 58 and Table 59

Table 58. MODS Oversampling Modes

(S)MODS1

(S)MODS0

Power Mode

00

Normal

0

1

Low Noise Low Power

1

0

High Resolution

1

1

Low Power

Table 59. MODS Oversampling Modes Current Consumption and Averaging Values at each ODR

Mode

Normal (00)

Low Noise Low Power (01)

High Resolution (10)

Low Power (11)

ODR

Current

Current

OS Ratio

Current

1.56 Hz

24

128

8

32

165

1024

6

16

6.25 Hz

24

32

8

8

165

256

6

4

12.5 Hz

24

16

8

4

165

128

6

2

50 Hz

24

4

24

4

165

32

14

2

100 Hz

44

4

44

4

165

16

24

2

200 Hz

85

4

85

4

165

8

44

2

400 Hz

165

4

165

4

165

4

85

2

800 Hz

165

2

165

2

165

2

165

2