LIS2DH12 interrupt configuration

[Fikri Saman]

Hello,

I'm currently trying to configure the LIS2DH12 interrupt pin to wake up the CPU from sleep. I'm using SDK 15.2 with nRF52832. In the SDK there are files on the LIS2DH12 and there are two functions that I think might be for my case:

#define LIS2DH12_INT1_PIN_CFG(_s, _cl, _ia1, _ia2, _zyxda, _wtm, _ovr, _pol, _d4d) \
    LIS2DH12_INTERNAL_INT1_PIN_CFG(_s, _cl, _ia1, _ia2, _zyxda, _wtm, _ovr, _pol, _d4d)

#define LIS2DH12_INT1_CFG(_s, _thr, _dur, _aoi, _6d, _zh, _zl, _yh, yl, _xh, _xl, _lir) \
    LIS2DH12_INTERNAL_INT1_CFG(_s, _thr, _dur, _aoi, _6d, _zh, _zl, _yh, yl, _xh, _xl, _lir)

I'm not sure if I have to use both or one of them and I don't know what is the correct configuration to give for my case. Can anybody help me please?

[Otso Jousimaa]

First you should let us know when exactly LIS2DH12 should wake the CPU. FIFO buffer overflow? Some activity threshold exceeded? 

ST also provides drivers for their ICs, github.com/.../STMems_Standard_C_drivers

[Fikri Saman]

Hi Otso,

Sorry for the lack of detail. I'm still new to this but essentially I want LIS2DH12 to wake up the CPU when there is a huge movement.

[Otso Jousimaa]

I'm not sure on how exactly it would work with that Nordic macro, here's how I do it on ST drivers: 

https://github.com/ruuvi/ruuvi.drivers.c/blob/e23f24bf0902e0fb0edcaba00f28bd33dba64079/src/interfaces/acceleration/ruuvi_interface_lis2dh12.c#L949 . 

* Enable high-pass on INT1 to not trigger due to gravity.
* Enable Interrupt 1 on pin 2 (pin 1 is reserved for watermark in my case).
* Enable interrupt on XYZ axis high.
* Convert desired threshold to LSB, depending on the set scale.

It's possible to determine the exact bytes from datasheet.

[Nguyen Hoan Hoang]

There is a good driver here github.com/.../accel_lis2dh12.cpp