Ultra Low Power Mode for LSM6DS032 is not working.

[bimalpaneru]

Currently designing a  low power embedded system for monitoring application using IMU LSM6DS032, tried both low power/normal mode and the ultra low power mode setting on this IMU, but I could not find the significant difference in the power consumption in these modes.
Any suggestion on the way I am configuring the IMU in ULP mode would be really appreciated.
Steps taken to turning on the Ultra low power mode

1. Accelerometer is powered-down by setting ODR_[3:0] bits to 0b0000 in CTRL1_XL register.
2. Gyroscope is powered-down by setting the bits ODR_[3:0] = b0000 of CTRL2_G register.
3. Setting XL_ULP_EN bit of CTRL5_C to 1.
4. Setting XL_HM_MODE of CTRL6_C to  0.
5. Using the FSR of 4G and ODR of 208

Current draw for the MCU interface with IMU is ~2mA  with IMU in ULP/Low-Power mode and MCU in deep sleep. We were expecting draw to be at least in uA range. MCU only deep sleep is ~600uA. Seems like IMU is drawing more than 1mA.

Thank you

[Federica Bossi]

Hi @bimalpaneru ,

Welcome to ST Community!

This is the current consumption reading using LSM6DSO32 with STEVAL-MKI109V3:

However, as you can see reading the datasheet, it is not possible to set ODR 208Hz when you are in ULP mode, so I can't give you a current consumption values.

In addition, when you set to '0' xl_hp mode, you enable the HP mode:

 

[bimalpaneru]

Hi @Federica Bossi ,

Thank you for you reply.
Can you please clarify on these?
Datasheet says for ULP mode for ODR_XL between 1.6 Hz and 208 Hz possible. Is this a open range rather than closed?

Also, the application note section 3.5 mentions Six low-speed ODRs can be chosen for the accelerometer through the ODR_XL bits: 1.6 Hz, 12.5 Hz,26 Hz, 52 Hz, 104 Hz, and 208 Hz. The gyroscope must be set in power-down mode.

And, section 6.2.1 of datasheet says, When ULP mode is intended to be used, the bit XL_HM_MODE must be set to 0, which turns the HP mode on. Does this bit have to be '1' for ULP mode?

[okay_computer]

Hi @Federica Bossi 

Following up for this clarification. 

Thanks