LIS2DS12 datasheet(30/68 Pages) STMICROELECTRONICS

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LIS2DS12

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DocID027753 Rev 4

5.5.1

Step detector/Step counter

The step detector function generates an interrupt when a step is recognized, the step

counter (automatically enabled when step detector is on) counts the number of the steps

detected.

Step Detector/Step Counter (SD/SC) are enabled by setting to ‘1’-logic the STEP_CNT_ON

bit in the FUNC_CTRL (3Fh) register. Additional pedometer advanced configurations can be

used if the FUNC_CFG_EN bit in CTRL2 (21h) is set to "1". Details of the pedometer

advanced configuration registers are available in Section 9: Advanced configuration register

mapping and Section 10: Advanced configuration registers description. To disable the

pedometer advanced configurations, the FUNC_CFG_EN bit in CTRL2 (3Fh) must be set to

'0'. Refer to Section 10.8: CTRL2 (3Fh).

The “step detected” interrupt can be read in the FUNC_CK_GATE (3Dh) register and by

writing the INT2 STEP DET bit to ‘1’-logic in the CTRL5 (24h) register, it can be routed on

INT2. The number of steps detected can be read from STEP_COUNTER_L (3Bh) and

STEP_COUNTER_H (3Ch) registers (65535 steps max).

Writing the register STEP_COUNTER_MINTHS (3Ah) it is possible to configure the SD/SC

minimum threshold, enable 4 g operation and reset the number of steps:

 Minimum threshold is the value at which the threshold for step recognition asymptotically

tends if no steps are detected and below which it cannot descend (refer to Figure 12).

Figure 12. Pedometer (step recognition) minimum threshold

 As default, SD/SC operates with data scaled at 2 g of full scale (device full-scale

independent), but it is possible to make it work with a FS of 4 g by setting the PEDO4g bit

to ‘1’-logic.

 The number of steps can be reset by writing the bit RST nSTEP to ‘1’-logic in

STEP_COUNTER_MINTHS (3Ah): this is a synchronous reset activated at the first data

valid and before the algorithm execution. The bit is auto-reset once the counter has been

successfully set to 0000h. This bit does not reset the algorithm and its variables.

LIS2DS12 Datasheet(PDF) 30 Page - STMicroelectronics