MMA8451 datasheet(37/47 Pages) FREESCALE

37 / 47 page

MMA8452Q

Sensors

Freescale Semiconductor, Inc.

6.7

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).

0x2A: CTRL_REG1 System Control 1 Register

It is important to note that when the device is Auto-SLEEP mode, the system ODR and the data rate for all the system

functional blocks are overridden by the data rate set by the ASLP_RATE field.

DR[2:0] bits select the Output Data Rate (ODR) for acceleration samples. The default value is 000 for a data rate of 800 Hz.

ACTIVE bit selects between STANDBY mode and ACTIVE mode. The default value is 0 for STANDBY mode.

LNoise bit selects between normal full dynamic range mode and a high sensitivity, Low-Noise mode. In Low-Noise mode the

maximum signal that can be measured is ±4g. Note: Any thresholds set above 4g will not be reached.

F_Read bit selects between Normal and Fast Read mode. When selected, the auto-increment counter will skip over the LSB data

bytes.

0x2A: CTRL_REG1 Register (Read/Write)

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

ASLP_RATE1

ASLP_RATE0

DR2

DR1

DR0

LNOISE

F_READ

ACTIVE

Table 53. CTRL_REG1 Description

ASLP_RATE[1:0]

Configures the Auto-WAKE sample frequency when the device is in SLEEP Mode. Default value: 00.

See Table 54 for more information.

DR[2:0]

Data rate selection. Default value: 000.

See Table 55 for more information.

LNOISE

Reduced noise reduced Maximum range mode. Default value: 0.

(0: Normal mode; 1: Reduced Noise mode)

F_READ

Fast Read mode: Data format limited to single Byte Default value: 0.

(0: Normal mode 1: Fast Read Mode)

ACTIVE

Full Scale selection. Default value: 00.

(0: STANDBY mode; 1: ACTIVE mode)

Table 54. SLEEP Mode Rate Description

ASLP_RATE1

ASLP_RATE0

Frequency (Hz)

12.5

6.25

1.56

Table 55. System Output Data Rate Selection

DR2

DR1

DR0

ODR

Period

800 Hz

1.25 ms

400 Hz

2.5 ms

200 Hz

5 ms

100 Hz

10 ms

50 Hz

20 ms

12.5 Hz

80 ms

6.25 Hz

160 ms

1.56 Hz

640 ms

Table 56. Full Scale Selection

Active

Mode

0STANDBY

1ACTIVE

MMA8451 Datenblatt(PDF) 37 Page - Freescale Semiconductor, Inc

MMA8451 Datenblatt(HTML) 37 Page - Freescale Semiconductor, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

Datenblatt Download

Link URL