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TM.634
Visitor II
October 30, 2019
Question

Free fall detection with LIS3DH accelerometers

  • October 30, 2019
  • 1 reply
  • 915 views

Hello,

I'm having problems with free fall interrupt. I set every register that needed to be set with values that are written in application note of sensor.

57h to CTRL_REG1

00h to CTRL_REG2

40h to CTRL_REG3

00h to CTRL_REG4

08h to CTRL_REG5

16h to INT1_THS

03h to INT1_DURATION

95h to INT1_CFG

Read INT1_SRC after interrupt happens.

I'm using NUCLEO F091RC where i'm detecting external interrupts on INT1 pin.

I think it happened once that interrupt was triggered but that's it or maybe pull-down resistors weren't set at that time.

I really don't have any idea what's wrong. DRDY signal on INT1 doesnt work either and was set like FF interrupt from application note.

I would really appriciate help from you.

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    1 reply

    E
    Eleon BORLINI
    ST Employee
    November 4, 2019

    Hi @TM.634​ , on which pin of the NUCLEO F091RC board did you wired the INT1 pin of the LIS3DH? Did you check if it is not a reserved line (also with an oscilloscope)? Supposing everything is ok from an HW p.o.v., can you please confirm me you are reading sensible data and no issue on I2C/SPI communication? One test you could do is to increase or decrease the free fall threshold (actually 16h = 350mg in INT1_THS). Regards

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