Chip select operation on MEMS sensor ISM330DLC and others.

[MKear]

Hello,

I'm just looking at the CS pin operation of ISM330DLC and other ST mems sensors. It seems the when (CS=1) its in I2C mode. When (CS=0) its in SPI mode.

Where I'm using multiple devices on an SPI channel with a sepearate CS for each device, what will stop the ISM330DLC operating in I2C mode with the SPI lines while it's not selected???

Is there something futher to this? Does the device enter SPI mode from the first (CS=0) and remain that way afterwards. One of the Bosch devices works like that.

Is it necessary to have a dedicated SPI channel for this device? I note the IIS2MDC appears to work in the same way.

Regards,

[Eleon BORLINI]

Hi @MKear​ , you are right, the CS can select the interface of the sensors. However, when you put sensors together and you communicate SPI with the only sensor with CS 0, the other sensors will not respond via I2C (ACK won't be recognized by the master). If you want to be sure of this, in addition you can write 1 into the bit I2C_disable of register CTRL4_C (13h). Regards

[MKear]

Thanks for your response. I can see that bit within the register now. Thankyou.