Sensor hub problems with LSM6DSV32X breakout, how to configure properly?

[rbmarcus]

I'm trying to add an LIS2MDL (STEVAL-MKI181V1) magnetometer to my LSM6DSV32X's (STEVAL-MKI240KA) sensor hub. I can't get the LSM6DSV32X to properly identify the LIS2MDL, and I'm not sure if it's a hardware- or firmware-related problem. My current hardware configuration is:

• SCx on MKI240KA tied to SCL on MKI181V1
• SDx on MKI240KA tied to SDA on MKI181V1
• INT2 on MKI240KA tied to DRDY on MKI181V1
• Jumpers on MKI240KA shifted to SCx/SDx positions
• CS on MKI181V1 tied to Vdd

For context I'm using Zephyr RTOS, but the initialization sequence for the LSM6DSV32X should be the same, especially since it fails right at the beginning when attempting to identify slaves. From the LA output, it looks like the LSM6DSV32X is trying to communicate with the external sensor but it can't sufficiently drive its SCx/SDx pins?

[Federica Bossi]

Hi @rbmarcus ,

Your hardware configuration seems correct, but ensure that there are pull-up resistors on the I2C lines (SCL and SDA). Please refer to the section 7 of AN6016 where the sensor hub mode is well described:

 

[rbmarcus]

Hello @Federica Bossi, 

I tested the internal pull-ups for the LSM6DSV32X, and separately I tested the system with external 4.7kOhm pull ups on the I2C lines, but in both cases the outcome is the same. From the logic analyzer readout, I can confirm that the pull ups are working properly and keeping the lines high when idle. 

[Federica Bossi]

Ok, so it could be a firmware issue. 

You should implement something similar to this example on LSM6DSV.