Datasheet

Sensors

NXP Semiconductors 21

MMA8452Q

ZYXOW is set whenever a new acceleration data is produced before completing the retrieval of the previous set. This event

occurs when the content of at least one acceleration data register (i.e., OUT_X, OUT_Y, OUT_Z) has been overwritten. ZYXOW

is cleared when the high-bytes of the acceleration data (OUT_X_MSB, OUT_Y_MSB, OUT_Z_MSB) of all the active channels are

read.

ZOW is set whenever a new acceleration sample related to the Z-axis is generated before the retrieval of the previous sample.

When this occurs the previous sample is overwritten. ZOW is cleared anytime OUT_Z_MSB register is read.

YOW is set whenever a new acceleration sample related to the Y-axis is generated before the retrieval of the previous sample.

When this occurs the previous sample is overwritten. YOW is cleared anytime OUT_Y_MSB register is read.

XOW is set whenever a new acceleration sample related to the X-axis is generated before the retrieval of the previous sample.

When this occurs the previous sample is overwritten. XOW is cleared anytime OUT_X_MSB register is read.

ZYXDR signals that a new sample for any of the enabled channels is available. ZYXDR is cleared when the high-bytes of the

acceleration data (OUT_X_MSB, OUT_Y_MSB, OUT_Z_MSB) of all the enabled channels are read.

ZDR is set whenever a new acceleration sample related to the Z-axis is generated. ZDR is cleared anytime OUT_Z_MSB register

is read.

YDR is set whenever a new acceleration sample related to the Y-axis is generated. YDR is cleared anytime OUT_Y_MSB register

is read.

XDR is set whenever a new acceleration sample related to the X-axis is generated. XDR is cleared anytime OUT_X_MSB register

is read.

Data registers: 0x01: OUT_X_MSB, 0x02: OUT_X_LSB, 0x03: OUT_Y_MSB, 0x04: OUT_Y_LSB, 0x05: OUT_Z_MSB, 0x06:

OUT_Z_LSB

These registers contain the X-axis, Y-axis, and Z-axis 12-bit output sample data expressed as 2's complement numbers. The

sample data output registers store the current sample data.

OUT_X_MSB, OUT_X_LSB, OUT_Y_MSB, OUT_Y_LSB, OUT_Z_MSB, and OUT_Z_LSB are stored in the auto-incrementing

address range of 0x01 to 0x06 to reduce reading the status followed by 12-bit axis data to seven bytes. If the F_READ bit is set

(0x2A bit 1), auto-increment will skip over LSB registers. This will shorten the data acquisition from seven bytes to four bytes.

The LSB registers can only be read immediately following the read access of the corresponding MSB register. A random read

access to the LSB registers is not possible. Reading the MSB register and then the LSB register in sequence ensures that both

bytes (LSB and MSB) belong to the same data sample, even if a new data sample arrives between reading the MSB and the LSB

byte.

0x01: OUT_X_MSB: X_MSB register (read only)