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Visitor II
September 21, 2018
Question

LSM9DS1 CTRL_REG3_M SIM bit usage

  • September 21, 2018
  • 1 reply
  • 635 views

The datasheet states that the the SIM (SPI Mode Selection) bit in the CTRL_REG3_M of the LSM9DS1 sensor enables only SPI read, if the bit is set, although my measurements with an oscilloscope shows quite the oppposite.

Is it possible that the datasheet is incorrect and the functionality is 0: SPI RD+WR; 1: SPI WR?

Details: without any initialization and reading the WHO_AM_I_M register I get a response, but if I set the SIM bit in CTRL_REG3_M, the SDI line stays HIGH.

My conclusion should be right, because the only change I've made was setting of the SIM bit, and as I've written, my proof was an oscilloscope.

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    1 reply

    ST Employee
    September 23, 2018

    Yes, you are right, it is opposite. it is bug in the datasheet.