LIS3DH.Interrupts (lis3dh v0.1.0)

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Encoding and decoding for the LIS3DH's inertial interrupt configuration (INT1_CFG, INT1_THS, INT1_DURATION and their INT2_* siblings) plus the per-pin routing bits in CTRL_REG3 and CTRL_REG6 and the latching/4D bits in CTRL_REG5.

The chip has two physical interrupt pins, INT1 and INT2, each driven by a configurable mix of event sources:

  • inertial interrupts 1 / 2 (AOI engines reading INT*_CFG),
  • click detection,
  • data-ready for accelerometer (ZYXDA) or auxiliary ADC (321DA),
  • FIFO watermark / overrun (INT1 only — handled by LIS3DH.Sampler),
  • activity / boot (INT2 only).

An inertial interrupt fires when the per-axis event flags in INT*_CFG combine according to the AOI / 6D bits:

AOI  6D   Behaviour
 0   0   OR of the enabled axis events (e.g. wake-up / motion)
 0   1   6D movement recognition (entering a known zone)
 1   0   AND of the enabled axis events (e.g. free-fall)
 1   1   6D position recognition (currently in a known zone)

Threshold and duration registers carry units that depend on the configured full-scale range and ODR; see threshold_lsb_mg/1 and the helpers in LIS3DH for unit-aware wrappers.

Summary

Types

aoi_mode()

Combined AOI/6D field in INT*_CFG.

axis_event()

Per-axis-direction event flags. Each entry enables interrupt generation when the named axis crosses the configured threshold in the named direction.

pin()

Which interrupt pin a configuration applies to.

source_flags()

Decoded INT*_SRC flags. :active is the master IA bit; the per-axis fields report which axis-direction events fired during the latched window (or this read, for non-latched mode).

Functions

decode_int_cfg(arg)

Decode an INT*_CFG byte into a map of its fields.

decode_int_src(arg)

Decode an INT*_SRC byte into a map of its fields.

encode_duration!(count)

Encode a duration in ODR counts into a 7-bit INT*_DURATION register value. Each LSB is 1/ODR (so at 100 Hz, count=1 ≈ 10 ms).

encode_int_cfg(opts \\ [])

Encode an INT*_CFG byte from keyword options.

encode_threshold!(threshold_mg, range)

Encode a threshold in milli-g into a 7-bit INT*_THS register value for the given range. Rounds down. Clamps at the 7-bit maximum (127).

threshold_lsb_mg(range)

Returns the threshold register's LSB size in milli-g for the given full- scale range, per datasheet §8.23 / §8.27.

Types

aoi_mode()

@type aoi_mode() :: :or | :and | :six_d_movement | :six_d_position

Combined AOI/6D field in INT*_CFG.

  • :or — OR of enabled axis events.
  • :and — AND of enabled axis events.
  • :six_d_movement — interrupt when orientation enters a known zone.
  • :six_d_position — interrupt while orientation is inside a known zone.

axis_event()

@type axis_event() :: :x_high | :x_low | :y_high | :y_low | :z_high | :z_low

Per-axis-direction event flags. Each entry enables interrupt generation when the named axis crosses the configured threshold in the named direction.

pin()

@type pin() :: :int1 | :int2

Which interrupt pin a configuration applies to.

source_flags()

@type source_flags() :: %{
  active: boolean(),
  x_high: boolean(),
  x_low: boolean(),
  y_high: boolean(),
  y_low: boolean(),
  z_high: boolean(),
  z_low: boolean()
}

Decoded INT*_SRC flags. :active is the master IA bit; the per-axis fields report which axis-direction events fired during the latched window (or this read, for non-latched mode).

Functions

decode_int_cfg(arg)

@spec decode_int_cfg(<<_::8>>) :: %{mode: aoi_mode(), axes: [axis_event()]}

Decode an INT*_CFG byte into a map of its fields.

decode_int_src(arg)

@spec decode_int_src(<<_::8>>) :: source_flags()

Decode an INT*_SRC byte into a map of its fields.

encode_duration!(count)

@spec encode_duration!(0..127) :: <<_::8>>

Encode a duration in ODR counts into a 7-bit INT*_DURATION register value. Each LSB is 1/ODR (so at 100 Hz, count=1 ≈ 10 ms).

encode_int_cfg(opts \\ [])

@spec encode_int_cfg(keyword()) :: <<_::8>>

Encode an INT*_CFG byte from keyword options.

Options

encode_threshold!(threshold_mg, range)

@spec encode_threshold!(non_neg_integer(), LIS3DH.Config.range()) :: <<_::8>>

Encode a threshold in milli-g into a 7-bit INT*_THS register value for the given range. Rounds down. Clamps at the 7-bit maximum (127).

threshold_lsb_mg(range)

@spec threshold_lsb_mg(LIS3DH.Config.range()) :: pos_integer()

Returns the threshold register's LSB size in milli-g for the given full- scale range, per datasheet §8.23 / §8.27.