Setting sensor hub master i2c clock speed

el659 · ‎2024-01-12

Hi @Federica Bossi , I need help with setting LSM6DSO sensor hub i2c master clock speed.

How do I set the master i2c clock speed between LSM6DSO and external sensor for sensor hub operation? Is there registers or something else on LSM6DSO that controls master i2c clock speed between external sensors?

If there is anything I am mistaken about, please do correct me.

Thanks,

Federica Bossi · ‎2024-01-16

Hi @el659 ,

In LSM6DSO you can't modify the I2C clock of the sensorhub

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Federica Bossi · ‎2024-01-12

Hi @el659 ,

It's all described in section 7 of AN5192, please refer to it.

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el659 · ‎2024-01-12

Hi @Federica Bossi,

I have read through section 7 of AN5192 but I haven't found anything about master i2c clock speed between LSM6DSO and external sensor during sensor hub operation but SHUB_ODR[1:0] in MASTER_CONFIG, which is something you already replied in my previous post.

i2c clock speed can be up to 400 khz but this number is never close 104 hz and seeing that it is SHUB_"ODR"_[1:0], this cannot be the i2c clock speed, right?

el659 · ‎2024-01-12

@jocktmpbd7

Ive read through the datasheet and couldn't find it. That's why I am asking the forum for help.

Nothing but MASTER_CONFIG mentions master i2c configuration but even the bits in this register don't mention anything about "clock speed".
Ive also read through other registers to see if I missed anything but I haven't found anything about clock speed. I could be wrong cuz my eyes are tired after reading the datasheet for hours.

TDK · ‎2024-01-12

The datasheet does seem lacking here. Did you try it? I would bet it is fixed to either 100 kHz or 400 kHz internally without the option to change it.

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el659 · ‎2024-01-12

I haven't checked it yet cuz I thought I would be able to change the clock speed through software, but now that you mention it, I think that could be very likely since AN5192 mentions external pull ups are optional for SDx and SCx pins. I will give it shot with oscilloscope and come back to it. In the meantime, I really hope someone has an answer for it.

Thank you for your advice @TDK

Federica Bossi · ‎2024-01-16

Hi @el659 ,

In LSM6DSO you can't modify the I2C clock of the sensorhub

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el659 · ‎2024-01-16

Hi @Federica Bossi

Thank you for the valuable of information.

Could you also tell me the fixed sensorhub's i2c clock speed, since it is also not on the datasheet?

Federica Bossi · ‎2024-01-19

Hi @el659 ,

It is about 100kHz.

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