MMA8452QR1 Freescale Semiconductor, MMA8452QR1 Datasheet - Page 29

• Manufacturer Part Number: MMA8452QR1
• Description: Board Mount Accelerometers LOW G 3-AXIS 12BT EX VLT
• Manufacturer: Freescale Semiconductor

Specifications of MMA8452QR1

• Sensing Axis: X, Y, Z
• Acceleration: 2 g, 4 g, 8 g
• Digital Output - Number Of Bits: 8 bit, 12 bit
• Supply Voltage (max): 3.6 V
• Supply Voltage (min): 1.95 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Digital Output - Bus Interface: I2C
• Shutdown: Yes
• Sensitivity: 256 count/g, 512 count/g, 1024 count/g
• Package / Case: QFN-16
• Output Type: Digital
• Rohs Compliant: Yes
• Peak Reflow Compatible (260 C): Yes
• Acceleration Range: ± 2g, ± 4g, ± 8g
• No. Of Axes: 3
• Ic Interface Type: I2C
• Sensor Case Style: QFN
• No. Of Pins: 16
• Supply Voltage Range: 1.95V To 3.6V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

0x14: P_L_THS_REG Portrait/Landscape Threshold and Hysteresis Register
:
Table 25. Trip Angles with Hysteresis for 45° Angle
6.3
bit 6). The freefall/motion detection block can be disabled by setting all three bits ZEFE, YEFE, and XEFE to zero.
operate in four different modes:
Mode 1: Freefall Detection with ELE = 0, OAE = 0
XEFE control bits determine which axes are considered for the freefall detection. Once the EA bit is set, and DBCNTM = 0, the
EA bit can get cleared only after the delay specified by FF_MT_COUNT. This is because the counter is in decrement mode. If
DBCNTM = 1, the EA bit is cleared as soon as the freefall condition disappears, and will not be set again before the delay
specified by FF_MT_COUNT has passed. Reading the FF_MT_SRC register does not clear the EA bit. The event flags (0x16)
ZHE, ZHP, YHE, YHP, XHE, and XHP reflect the motion detection status (i.e. high g event) without any debouncing, provided that
the corresponding bits ZEFE, YEFE, and/or XEFE are set.
Mode 2: Freefall Detection with ELE = 1, OAE = 0
time value for the set threshold, the EA bit is set, and remains set until the FF_MT_SRC register is read. When the FF_MT_SRC
register is read, the EA bit and the debounce counter are cleared and a new event can only be generated after the delay specified
by FF_MT_CNT. The ZEFE, YEFE, and XEFE control bits determine which axes are considered for the freefall detection. While
EA = 0, the event flags ZHE, ZHP, YHE, YHP, XHE, and XHP reflect the motion detection status (i.e., high g event) without any
debouncing, provided that the corresponding bits ZEFE, YEFE, and/or XEFE are set. The event flags ZHE, ZHP, YHE, YHP, XHE,
and XHP are latched when the EA event bit is set. The event flags ZHE, ZHP, YHE, YHP, XHE, and XHP will start changing only
after the FF_MT_SRC register has been read.
Mode 3: Motion Detection with ELE = 0, OAE = 1
control bits determine which axes are taken into consideration for motion detection. Once the EA bit is set, and DBCNTM = 0,
the EA bit can get cleared only after the delay specified by FF_MT_COUNT. If DBCNTM = 1, the EA bit is cleared as soon as the
motion high g condition disappears. The event flags ZHE, ZHP, YHE, YHP, XHE, and XHP reflect the motion detection status
(i.e., high g event) without any debouncing, provided that the corresponding bits ZEFE, YEFE, and/or XEFE are set. Reading the
FF_MT_SRC does not clear any flags, nor is the debounce counter reset.
Mode 4: Motion Detection with ELE = 1, OAE = 1
axes are taken into consideration for motion detection. Once the debounce counter reaches the threshold, the EA bit is set, and
remains set until the FF_MT_SRC register is read. When the FF_MT_SRC register is read, all register bits are cleared and the
debounce counter are cleared and a new event can only be generated after the delay specified by FF_MT_CNT. While the bit
EA is zero, the event flags ZHE, ZHP, YHE, YHP, XHE, and XHP reflect the motion detection status (i.e., high g event) without
any debouncing, provided that the corresponding bits ZEFE, YEFE, and/or XEFE are set. When the EA bit is set, these bits keep
their current value until the FF_MT_SRC register is read.
Table 24. P_L_THS_REG Description
Sensors
Freescale Semiconductor
0x14: P_L_THS_REG Register (Read/Write)
P_L_THS[7:3]
P_L_THS[4]
This register represents the Portrait to Landscape trip threshold.
The freefall/motion function can be configured in either freefall or motion detection mode via the OAE configuration bit (0x15
Depending on the register bits ELE (0x15 bit 7) and OAE (0x15 bit 6), each of the freefall and motion detection block can
In this mode, the EA bit (0x16 bit 7) indicates a freefall event after the debounce counter is complete. The ZEFE, YEFE, and
In this mode, the EA event bit indicates a freefall event after the debounce counter. Once the debounce counter reaches the
In this mode, the EA bit indicates a motion event after the debounce counter time is reached. The ZEFE, YEFE, and XEFE
In this mode, the EA bit indicates a motion event after debouncing. The ZEFE, YEFE, and XEFE control bits determine which
HYS[2:0]
Bit 7
Register Value
Hysteresis
Motion and Freefall Embedded Function Registers
4
Portrait/Landscape Fixed Threshold angle = 1_0000 (45°).
This is a fixed angle added to the threshold angle for a smoother transition from Portrait to Landscape and Landscape to
Portrait. This angle is fixed at ±14°, which is 100.
P_L_THS[3]
Bit 6
P_L_THS[2]
Bit 5
± Angle Range
Hysteresis
±14
P_L_THS[1]
Bit 4
P_L_THS[0]
Landscape to Portrait
Bit 3
Trip Angle
59°
HYS[2]
Bit 2
Portrait to Landscape
HYS[1]
Bit 1
Trip Angle
31°
MMA8452Q
HYS[0]
Bit 0
29