LIS25BA datasheet(17/32 Pages) STMICROELECTRONICS

номер детали	LIS25BA

подробное описание детали	MEMS digital output motion sensor: low-noise, high-bandwidth 3-axis accelerometer with TDM interface

PDF	32 Pages

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производитель	STMICROELECTRONICS [STMicroelectronics]

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LIS25BA

TDM interface specifications

In order to support a serial clock BCLK variable in the range [1024 MHz, 12.288 MHz], and

consequently to compute the correct maximum value of the internal TDM counter, two

possible solutions can be selected:



The cmax value at the input of the TDM interface can be computed on the fly

employing the BCLK_AUTO block (see Figure 6), which is able to compute the cmax

value using Equation 1. This functionality by default is enabled, and can be disabled

employing the I²C register ODR_AUTO_EN (AXES_CTRL_REG (2Fh) bit 0).



The TDM cmax can be programmed through the I²C registers TDM_cmax (24h-25h).

4.4

TDM axes mapping

Within one frame, the data signal (DOUT) is divided into multiple segments. We call each

segment a slot thereafter in this document.

The data slot width is fixed and equal to 16 bits.

In each slot, data should be left-justified (MSB first).

The number of slots in a WCLK frame can be variable, and it depends on the ratio

between

BCLK and WCLK. However, as depicted in Figure 7 and Figure 8, only the slots 0,1,2

and 4,5,6 can be used to send accelerometer data, all the others slots are always set in

high-impedance.

The mapping between the input data and the TDM output slots is flexible and can be

configured through the I²C register mapping (TDM_CTRL_REG (2Eh) bit 4) in Figure 6

In particular two possible configurations can be selected:



Axes data (X,Y,Z) mapped on TDM slots (0,1,2) (mapping = 0)



Axes data (X,Y,Z) mapped on TDM slots (4,5,6) (mapping = 1)

Figure 7. Axes X, Y, Z mapped to SLOT0, SLOT1, SLOT2

Figure 8. Axes X, Y, Z mapped to SLOT4, SLOT5, SLOT6

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