ISM303DAC datasheet(40/80 Pages) STMICROELECTRONICS

40 / 80 page

Functionality

ISM303DAC

40/80

DocID030988 Rev 2

4.4.6

Module-to-FIFO

When the MODULE_TO_FIFO bit in the FIFO_CTRL_A (25h) register is set to '1', the 14-bit

magnitude of the vector of the current axes is sent as FIFO input instead of axes data. X-, Y-

and Z-axis data are replaced with 3 times the adjacent data generated by the module

routine, as shown in Figure 14, so a row of FIFO is written every 3 axes data ready.

The module routine must be previously enabled by writing to the FUNC_CTRL_A (3Fh)

The module data in FIFO can be read as output data in the registers 28h-2Dh.

The ISM303DAC calculates the vector sum of the acceleration of the X-, Y-, Z-axis using the

following formula:

module (14-bit) = Sqrt(x2+y2+z2)

The implementation is based on an approximation of this formula (error below noise level).

As shown in Figure 14, when module-to-FIFO is enabled, each row of FIFO contains 3

values of the module, related to 3 consecutive ODR.

Figure 14. Module-to-FIFO mode example

4.5

Factory calibration

The IC interface is factory calibrated for sensitivity (LA_So, M_GN), Zero-g level (LA_TyOff)

and Zero-gauss level (M_TyOff).

The trim values are stored inside the device in nonvolatile memory. Anytime the device is

turned on, the trim parameters are downloaded into the registers to be used during active

operation. This allows using the device without further calibration.

ISM303DAC データシート(PDF) 40 Page - STMicroelectronics