AN2381 datasheet(33/47 Pages) STMICROELECTRONICS

33 / 47 page

AN2381

Registers Description

33/47

LIR defines whether the current direction/tilt status has to be latched inside the DD_SRC

request (if enabled through the IEND bit) it is necessary to perform a reading at the dummy

XHIE (YHIE, ZHIE) configure the device to recognize whether the acceleration value along

the X axis has exceeded the preset threshold module in the positive direction of the related

acceleration axis.

XLIE (YLIE, ZLIE) configure the device to recognize whether the acceleration value along

the X axis has exceeded the preset threshold module in the negative direction of the related

acceleration axis. In order to avoid false detections and/or bouncing produced for example

by either spurious vibration or tremor, one inner/internal and one outer/external thresholds is

defined. Both the thresholds are expressed over 16 bit as an unsigned number and are

given respectively by the concatenation of DD_THSI_H & DD_THSI_L and DD_THSE_H &

DD_THSE_L. Whenever the inner thresholds is greater than the outer one, the hysteresis

region will be null and the threshold used to detect the tilt direction is DD_THSE_H &

DD_THSE_L.

X, (Y, Z) acceleration data is considered high when the acceleration value of the X (Y, Z)

channel is higher than the outer DD_THSE_H & DD_THSE_L threshold (i.e. acceleration

exceeding the threshold in module with the terminal tilted in the positive acceleration

direction).

Similarly, X, (Y, Z) acceleration data is considered low when the acceleration value of the X

(Y, Z) channel is lower than the outer DD_THSE_H & DD_THSE_L threshold (i.e.

acceleration exceeding the threshold in module but terminal tilted in the negative

acceleration direction).

Both X (Y, Z) high and X (Y, Z) low in DD_SRC register are reset when the absolute

acceleration data on X (Y, Z) channel is lower than the inner DD_THSI_H & DD_THSI_L

threshold. Figure 13 gives a representation of acceleration area named “high”, “low” and

“reset” defined by thresholds written in DD_THSE and DD_THSI registers on a single

acceleration axis.

Figure 13.

DD_CFG High and Low Description

+ Full Scale

- Full Scale

0 g level

External Threshold (DD_THSE)

X (Y, Z) high

X (Y, Z) low

X (Y, Z) reset

Positive

Negative

Internal Threshold (DD_THSI)

Hysteresis Region

Internal Threshold (DD_THSI)

Hysteresis Region

acceleration

AN2381 Datasheet(PDF) 33 Page - STMicroelectronics

AN2381 Datasheet(HTML) 33 Page - STMicroelectronics

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

Datasheet Download

Link URL