Unit of minimum threshold in LIS2DS12

[AB.4]

Hello ST community,

In LIS2DS12 application note, section 5.9.1, it is mentioned that the minimum threshold can be set where 1 LSB = FS/64. I would like to confirm if the value in this register has the unit of g.

Also, if +- 2g is the selected full scale, 1 LSB in STEP_COUNTER_MINTHS is 2/64, right?

Regards,

Anusha

[Eleon BORLINI · Accepted solution]

Hi @AB.4​ , are you referring to the embedded step counter threshold, right? I confirm you the unit is "g", and the STEP_COUNTER_MINTHS (3Ah) is a 6-bit unsigned value, with 1 LSB = 1/64 of FS. To be more specific, this means that in the 2g case the minimum threshold is 2g/64=31.25mg, while in the 4g case is 4g/64=62.5mg.

Please keep in mind that the minimum threshold for step counter recognition is set to a default of 01 0000 in STEP_COUNTER_MINTHS (3Ah) (datasheet p. 57)

As a side note, please consider also that the other threshold definitions are different. For example:

• Threshold for TAP recognition (TAP_6D_THS (31h) register): 4-bit unsigned, 1 LSB = FS/32
• Free-fall threshold: 3-bit unsigned, 1 LSB = 31.25 mg
• Wakeup threshold: 6-bit unsigned, 1 LSB = 1/64 of FS

Regards