ISM330BXTR datasheet(37/150 Pages) STMICROELECTRONICS

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6.4

Gyroscope power modes

In the ISM330BX, the gyroscope can be configured in four different operating modes: power-down mode, sleep

mode, low-power mode and high-performance mode.

The operating mode selected depends on the value of the OP_MODE_G_[2:0] bits in CTRL2 (11h).

If the value of the OP_MODE_G_[2:0] bits is 000 (default), high-performance mode is valid for all ODRs (from

7.5 Hz up to 3.84 kHz).

Low-power mode is available for lower ODRs (7.5 Hz, 15 Hz, 30 Hz, 60 Hz, 120 Hz, 240 Hz) and it is enabled by

setting the the OP_MODE_G_[2:0] bits to 101.

6.5

Analog hub functionality

The ISM330BX embeds an analog hub sensing functionality which is able to connect an analog input and convert

it to a digital signal for embedded processing.

In the ISM330BX, the analog hub has a dedicated channel that can be activated by setting the AH_QVAR_EN bit

and the AH_QVAR1_EN / AH_QVAR2_EN bits to 1 in the CTRL7 (16h) register.

The accelerometer sensor must be set in high-performance mode when the analog hub channel is enabled.

The analog hub data-ready signal is represented by the AH_QVARDA bit of the STATUS_REG (1Eh) register.

This signal can be driven to the INT2 pin by setting the INT2_DRDY_AH_QVAR bit to 1 in the CTRL7 (16h)

Analog hub data are available as a 16-bit word in two’s complement in the AH_QVAR_OUT_L (3Ah) and

AH_QVAR_OUT_H (3Bh) registers.

The AH_QVAR_LPF bit in the CTRL9 (18h) register and the AH_QVAR_HPF bit in the CTRL8 (17h) register are

used to enable/disable, respectively, the embedded digital notch filter and the embedded digital high-pass filter

and to set the analog hub data rate and the overall bandwidth of the analog hub channel as shown in Table 21.

Analog hub data can be stored in FIFO (by setting the AH_QVAR_BATCH_EN bit to 1 in the

COUNTER_BDR_REG1 (0Bh) register) and can also be processed by MLC/FSM logic.

The equivalent input impedance of the analog hub buffers can be selected by properly setting the

AH_QVAR_C_ZIN_[1:0] bits in the CTRL7 (16h) register.

Finally, the AH_QVAR_SW bit in the CTRL7 (16h) register allows internally swapping the input connected to the

AH1/QVAR1 and AH2/QVAR2 pins.

6.6

Qvar functionality

The ISM330BX embeds a Qvar sensor which is able to detect electric charge variations in the proximity of the

external electrodes connected to the device.

In the ISM330BX, Qvar has a dedicated channel that can be activated by setting the AH_QVAR_EN bit and the

AH_QVAR1_EN / AH_QVAR2_EN bits to 1 in the CTRL7 (16h) register.

The accelerometer sensor must be set in high-performance mode when the Qvar channel is enabled.

The Qvar data-ready signal is represented by the AH_QVARDA bit of the STATUS_REG (1Eh) register. This

signal can be driven to the INT2 pin by setting the INT2_DRDY_AH_QVAR bit to 1 in the CTRL7 (16h) register.

Qvar data are available as a 16-bit word in two’s complement in the AH_QVAR_OUT_L (3Ah) and

AH_QVAR_OUT_H (3Bh) registers.

The AH_QVAR_LPF bit in the CTRL9 (18h) register and the AH_QVAR_HPF bit in the CTRL8 (17h) register are

used to enable/disable, respectively, the embedded digital notch filter and the embedded digital high-pass filter

and to set the Qvar data rate and the overall bandwidth of the Qvar channel as shown in Table 21.

Table 21. Analog hub / Qvar channel ODR and bandwidth configuration

AH_QVAR_LPF

AH_QVAR_HPF

AH / Qvar ODR (typ.)(1)

AH / Qvar bandwidth (typ.) [low, high]

240 Hz

[0 Hz, 318 Hz]

240 Hz

[0.15 Hz, 318 Hz]

120 Hz

[0 Hz, 14.8 Hz](2)

120 Hz

[0.08 Hz, 14.8 Hz](2)

1. The analog hub / Qvar channel ODR is equal to 240 Hz if the notch filter is disabled, otherwise the ODR is equal to 120 Hz.

2. First -3 dB crossing point

ISM330BX

Functionality

DS14588 - Rev 2

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