Nano 33 BLE Sense IMU (LSM9DS1) magnetometer ODR

Official Hardware Nano Family Nano 33 BLE Sense
1

Hello,

I am using the Nano 33 BLE Sense board and find that the register of the magnetometer needs to be configured separately.
In subsection 8.5 of LSM9DS1 datasheet https://www.st.com/resource/en/datasheet/lsm9ds1.pdf, it is CTRL_REG1_M (20h) register. It said that "FAST_ODR enables data rates higher than 80 Hz. " Does anyone know what is the accurate ODR if I enable this FAST_ODR?

In Arduino_LSM9DS1 library, the default setting is: writeRegister(LSM9DS1_ADDRESS_M, LSM9DS1_CTRL_REG1_M, 0xb4);
If I change it to writeRegister(LSM9DS1_ADDRESS_M, LSM9DS1_CTRL_REG1_M, 0xbe);, the ODR will be 80Hz or higher than 80 Hz (FAST_ODR)?

Thank you very much for your kind help in advance.

Tang

2

Hello Tang

I'm working on an update of the LSM9DS1 library.

There are functions for changing the sample rate of all the DOF.
So far I did not implement the above 80 Hz for magnetic.

What I found for the Gyro and the Accel is that the sample rate could differ significantly from the listed value.
Since ODR is in the tracking calculation of the Gyro, I needed a more accurate value.
I made a very rapid measuring method that gets callled upon setting a new ODR value. The get...ODR function returns the actual measured value.
This is not yet implemented for magnetic.

I'll have a look into it. If you can't wait, you can look in the code yourself for
float LSM9DS1Class::measureAccelGyroODR(unsigned int duration)
to adapt.

3

femmeverbeek:
Hello Tang

I'm working on an update of the LSM9DS1 library.
GitHub - FemmeVerbeek/Arduino_LSM9DS1: LSM9DS1 Library for Arduino
There are functions for changing the sample rate of all the DOF.
So far I did not implement the above 80 Hz for magnetic.

What I found for the Gyro and the Accel is that the sample rate could differ significantly from the listed value.
Since ODR is in the tracking calculation of the Gyro, I needed a more accurate value.
I made a very rapid measuring method that gets callled upon setting a new ODR value. The get...ODR function returns the actual measured value.
This is not yet implemented for magnetic.

I'll have a look into it. If you can't wait, you can look in the code yourself for
float LSM9DS1Class::measureAccelGyroODR(unsigned int duration)
to adapt.

Thank you so much for your kind help.

4

Ok this is what I did

A little tweak in the .CPP

int LSM9DS1Class::setMagnetODR(uint8_t range)  // range (0..15) = {0.625,1.25,2.5,5.0,10.0,20.0,40.0,80.0}Hz
{ uint8_t setting = ((range & 0b00000111) << 2) | ((range & 0b00001000) >> 2);
          setting = setting | (readRegister(LSM9DS1_ADDRESS_M, LSM9DS1_CTRL_REG1_M) & 0b11100001) ;
   return writeRegister(LSM9DS1_ADDRESS_M, LSM9DS1_CTRL_REG1_M,setting) ;	 
}

So a value above 7 sets the fast bit.

Result

magnetic field ODR param = 0 setting 0.63 Hz 
magnetic field ODR param = 1 setting 1.27 Hz 
magnetic field ODR param = 2 setting 2.54 Hz 
magnetic field ODR param = 3 setting 5.07 Hz 
magnetic field ODR param = 4 setting 10.15 Hz 
magnetic field ODR param = 5 setting 20.29 Hz 
magnetic field ODR param = 6 setting 40.55 Hz 
magnetic field ODR param = 7 setting 81.00 Hz 
magnetic field ODR param = 8 setting 405.67 Hz 
magnetic field ODR param = 9 setting 405.60 Hz 
magnetic field ODR param = 10 setting 405.71 Hz 
magnetic field ODR param = 11 setting 402.09 Hz 
magnetic field ODR param = 12 setting 402.27 Hz 
magnetic field ODR param = 13 setting 403.62 Hz 
magnetic field ODR param = 14 setting 404.18 Hz 
magnetic field ODR param = 15 setting 400.35 Hz

Aparently setting the fast_ODR bit works, but there is only one high ODR available.