ADXL343BCCZ Datasheet, PDF (24/36 Pages) Analog Devices – Digital MEMS Accelerometer

ADXL343
If the link bit is not set, the AUTO_SLEEP feature is disabled
and setting the AUTO_SLEEP bit does not have an impact on
device operation. Refer to the Link Bit section or the Link Mode
section for more information on utilization of the link feature.
When clearing the AUTO_SLEEP bit, it is recommended that the
part be placed into standby mode and then set back to measure-
ment mode with a subsequent write. This is done to ensure that
the device is properly biased if sleep mode is manually disabled;
otherwise, the first few samples of data after the AUTO_SLEEP
bit is cleared may have additional noise, especially if the device
was asleep when the bit was cleared.
Measure Bit
A setting of 0 in the measure bit places the part into standby mode,
and a setting of 1 places the part into measurement mode. The
ADXL343 powers up in standby mode with minimum power
consumption.
Sleep Bit
A setting of 0 in the sleep bit puts the part into the normal mode
of operation, and a setting of 1 places the part into sleep mode.
Sleep mode suppresses DATA_READY, stops transmission of data
to FIFO, and switches the sampling rate to one specified by the
wakeup bits. In sleep mode, only the activity function can be used.
When the DATA_READY interrupt is suppressed, the output
data registers (Register 0x32 to Register 0x37) are still updated
at the sampling rate set by the wakeup bits (D1:D0).
When clearing the sleep bit, it is recommended that the part be
placed into standby mode and then set back to measurement
mode with a subsequent write. This is done to ensure that the
device is properly biased if sleep mode is manually disabled;
otherwise, the first few samples of data after the sleep bit is
cleared may have additional noise, especially if the device was
asleep when the bit was cleared.
Wakeup Bits
These bits control the frequency of readings in sleep mode as
described in Table 20.
Table 20. Frequency of Readings in Sleep Mode
Setting
D1
D0
Frequency (Hz)
0
0
8
0
1
4
1
0
2
1
1
1
Data Sheet
Register 0x2E—INT_ENABLE (Read/Write)
D7
D6
D5
DATA_READY SINGLE_TAP DOUBLE_TAP
D3
D2
D1
Inactivity
FREE_FALL
Watermark
D4
Activity
D0
Overrun
Setting bits in this register to a value of 1 enables their respective
functions to generate interrupts, whereas a value of 0 prevents
the functions from generating interrupts. The DATA_READY,
watermark, and overrun bits enable only the interrupt output;
the functions are always enabled. It is recommended that interrupts
be configured before enabling their outputs.
Register 0x2F—INT_MAP (Read/Write)
D7
D6
D5
DATA_READY SINGLE_TAP DOUBLE_TAP
D3
D2
D1
Inactivity
FREE_FALL
Watermark
D4
Activity
D0
Overrun
Any bits set to 0 in this register send their respective interrupts to
the INT1 pin, whereas bits set to 1 send their respective interrupts
to the INT2 pin. All selected interrupts for a given pin are OR’ed.
Register 0x30—INT_SOURCE (Read Only)
D7
D6
D5
DATA_READY SINGLE_TAP DOUBLE_TAP
D4
Activity
D3
Inactivity
D2
FREE_FALL
D1
Watermark
D0
Overrun
Bits set to 1 in this register indicate that their respective functions
have triggered an event, whereas a value of 0 indicates that the
corresponding event has not occurred. The DATA_READY,
watermark, and overrun bits are always set if the corresponding
events occur, regardless of the INT_ENABLE register settings,
and are cleared by reading data from the DATAX, DATAY, and
DATAZ registers. The DATA_READY and watermark bits may
require multiple reads, as indicated in the FIFO mode descriptions
in the FIFO section. Other bits, and the corresponding interrupts,
are cleared by reading the INT_SOURCE register.
Register 0x31—DATA_FORMAT (Read/Write)
D7
D6 D5
D4 D3
D2
SELF_TEST SPI INT_INVERT 0 FULL_RES Justify
D1 D0
Range
The DATA_FORMAT register controls the presentation of data
to Register 0x32 through Register 0x37. All data, except that for
the ±16 g range, must be clipped to avoid rollover.
SELF_TEST Bit
A setting of 1 in the SELF_TEST bit applies a self-test force to
the sensor, causing a shift in the output data. A value of 0 disables
the self-test force.
SPI Bit
A value of 1 in the SPI bit sets the device to 3-wire SPI mode,
and a value of 0 sets the device to 4-wire SPI mode.
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