jepler/Adafruit_CircuitPython_ADXL34x
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity
Adafruit_CircuitPython_ADXL34x/adafruit_adxl34x.py
siddacious 22afa8e82e fixing typo regarding tap threshold
2020-04-24 12:25:09 -07:00

420 lines
16 KiB
Python
Executable file
Raw Permalink Blame History

# The MIT License (MIT)
#
# Copyright (c) 2018 Bryan Siepert for Adafruit Industries
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
"""
`adafruit_adxl34x`
====================================================
A driver for the ADXL34x 3-axis accelerometer family
* Author(s): Bryan Siepert
Based on drivers by K. Townsend and Tony DiCola
Implementation Notes
--------------------
**Hardware:**
https://www.adafruit.com/product/1231
**Software and Dependencies:**
* Adafruit CircuitPython firmware for the supported boards:
https://github.com/adafruit/circuitpython/releases
* Adafruit's Bus Device library: https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
"""
from micropython import const
from adafruit_bus_device import i2c_device
try:
from struct import unpack
except ImportError:
from ustruct import unpack
__version__ = "0.0.0-auto.0"
__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_ADXL34x.git"
# pylint: disable=bad-whitespace
_ADXL345_DEFAULT_ADDRESS = const(0x53) # Assumes ALT address pin low
# Conversion factors
_ADXL345_MG2G_MULTIPLIER = 0.004 # 4mg per lsb
_STANDARD_GRAVITY = 9.80665 # earth standard gravity
_REG_DEVID = const(0x00) # Device ID
_REG_THRESH_TAP = const(0x1D) # Tap threshold
_REG_OFSX = const(0x1E) # X-axis offset
_REG_OFSY = const(0x1F) # Y-axis offset
_REG_OFSZ = const(0x20) # Z-axis offset
_REG_DUR = const(0x21) # Tap duration
_REG_LATENT = const(0x22) # Tap latency
_REG_WINDOW = const(0x23) # Tap window
_REG_THRESH_ACT = const(0x24) # Activity threshold
_REG_THRESH_INACT = const(0x25) # Inactivity threshold
_REG_TIME_INACT = const(0x26) # Inactivity time
_REG_ACT_INACT_CTL = const(0x27) # Axis enable control for [in]activity detection
_REG_THRESH_FF = const(0x28) # Free-fall threshold
_REG_TIME_FF = const(0x29) # Free-fall time
_REG_TAP_AXES = const(0x2A) # Axis control for single/double tap
_REG_ACT_TAP_STATUS = const(0x2B) # Source for single/double tap
_REG_BW_RATE = const(0x2C) # Data rate and power mode control
_REG_POWER_CTL = const(0x2D) # Power-saving features control
_REG_INT_ENABLE = const(0x2E) # Interrupt enable control
_REG_INT_MAP = const(0x2F) # Interrupt mapping control
_REG_INT_SOURCE = const(0x30) # Source of interrupts
_REG_DATA_FORMAT = const(0x31) # Data format control
_REG_DATAX0 = const(0x32) # X-axis data 0
_REG_DATAX1 = const(0x33) # X-axis data 1
_REG_DATAY0 = const(0x34) # Y-axis data 0
_REG_DATAY1 = const(0x35) # Y-axis data 1
_REG_DATAZ0 = const(0x36) # Z-axis data 0
_REG_DATAZ1 = const(0x37) # Z-axis data 1
_REG_FIFO_CTL = const(0x38) # FIFO control
_REG_FIFO_STATUS = const(0x39) # FIFO status
_INT_SINGLE_TAP = const(0b01000000) # SINGLE_TAP bit
_INT_DOUBLE_TAP = const(0b00100000) # DOUBLE_TAP bit
_INT_ACT = const(0b00010000) # ACT bit
_INT_INACT = const(0b00001000) # INACT bit
_INT_FREE_FALL = const(0b00000100) # FREE_FALL bit
class DataRate: # pylint: disable=too-few-public-methods
"""An enum-like class representing the possible data rates.
Possible values are
- ``DataRate.RATE_3200_HZ``
- ``DataRate.RATE_1600_HZ``
- ``DataRate.RATE_800_HZ``
- ``DataRate.RATE_400_HZ``
- ``DataRate.RATE_200_HZ``
- ``DataRate.RATE_100_HZ``
- ``DataRate.RATE_50_HZ``
- ``DataRate.RATE_25_HZ``
- ``DataRate.RATE_12_5_HZ``
- ``DataRate.RATE_6_25HZ``
- ``DataRate.RATE_3_13_HZ``
- ``DataRate.RATE_1_56_HZ``
- ``DataRate.RATE_0_78_HZ``
- ``DataRate.RATE_0_39_HZ``
- ``DataRate.RATE_0_20_HZ``
- ``DataRate.RATE_0_10_HZ``
"""
RATE_3200_HZ = const(0b1111) # 1600Hz Bandwidth 140mA IDD
RATE_1600_HZ = const(0b1110) # 800Hz Bandwidth 90mA IDD
RATE_800_HZ = const(0b1101) # 400Hz Bandwidth 140mA IDD
RATE_400_HZ = const(0b1100) # 200Hz Bandwidth 140mA IDD
RATE_200_HZ = const(0b1011) # 100Hz Bandwidth 140mA IDD
RATE_100_HZ = const(0b1010) # 50Hz Bandwidth 140mA IDD
RATE_50_HZ = const(0b1001) # 25Hz Bandwidth 90mA IDD
RATE_25_HZ = const(0b1000) # 12.5Hz Bandwidth 60mA IDD
RATE_12_5_HZ = const(0b0111) # 6.25Hz Bandwidth 50mA IDD
RATE_6_25HZ = const(0b0110) # 3.13Hz Bandwidth 45mA IDD
RATE_3_13_HZ = const(0b0101) # 1.56Hz Bandwidth 40mA IDD
RATE_1_56_HZ = const(0b0100) # 0.78Hz Bandwidth 34mA IDD
RATE_0_78_HZ = const(0b0011) # 0.39Hz Bandwidth 23mA IDD
RATE_0_39_HZ = const(0b0010) # 0.20Hz Bandwidth 23mA IDD
RATE_0_20_HZ = const(0b0001) # 0.10Hz Bandwidth 23mA IDD
RATE_0_10_HZ = const(0b0000) # 0.05Hz Bandwidth 23mA IDD (default value)
class Range: # pylint: disable=too-few-public-methods
"""An enum-like class representing the possible measurement ranges in +/- G.
Possible values are
- ``Range.RANGE_16_G``
- ``Range.RANGE_8_G``
- ``Range.RANGE_4_G``
- ``Range.RANGE_2_G``
"""
RANGE_16_G = const(0b11) # +/- 16g
RANGE_8_G = const(0b10) # +/- 8g
RANGE_4_G = const(0b01) # +/- 4g
RANGE_2_G = const(0b00) # +/- 2g (default value)
# pylint: enable=bad-whitespace
class ADXL345:
"""Driver for the ADXL345 3 axis accelerometer
:param ~busio.I2C i2c_bus: The I2C bus the ADXL345 is connected to.
:param address: The I2C device address for the sensor. Default is ``0x53``.
"""
def __init__(self, i2c, address=_ADXL345_DEFAULT_ADDRESS):
self._i2c = i2c_device.I2CDevice(i2c, address)
self._buffer = bytearray(6)
# set the 'measure' bit in to enable measurement
self._write_register_byte(_REG_POWER_CTL, 0x08)
self._write_register_byte(_REG_INT_ENABLE, 0x0)
self._enabled_interrupts = {}
self._event_status = {}
@property
def acceleration(self):
"""The x, y, z acceleration values returned in a 3-tuple in m / s ^ 2."""
x, y, z = unpack("<hhh", self._read_register(_REG_DATAX0, 6))
x = x * _ADXL345_MG2G_MULTIPLIER * _STANDARD_GRAVITY
y = y * _ADXL345_MG2G_MULTIPLIER * _STANDARD_GRAVITY
z = z * _ADXL345_MG2G_MULTIPLIER * _STANDARD_GRAVITY
return (x, y, z)
@property
def events(self):
"""
``events`` will return a dictionary with a key for each event type that has been enabled.
The possible keys are:
+------------+----------------------------------------------------------------------------+
| Key | Description |
+============+============================================================================+
| ``tap`` | True if a tap was detected recently. Whether it's looking for a single or |
| | double tap is determined by the tap param of `enable_tap_detection` |
+------------+----------------------------------------------------------------------------+
| ``motion`` | True if the sensor has seen acceleration above the threshold |
| | set with `enable_motion_detection`. |
+------------+----------------------------------------------------------------------------+
|``freefall``| True if the sensor was in freefall. Parameters are set when enabled with |
| | `enable_freefall_detection` |
+------------+----------------------------------------------------------------------------+
"""
interrupt_source_register = self._read_clear_interrupt_source()
self._event_status.clear()
for event_type, value in self._enabled_interrupts.items():
if event_type == "motion":
self._event_status[event_type] = (
interrupt_source_register & _INT_ACT > 0
)
if event_type == "tap":
if value == 1:
self._event_status[event_type] = (
interrupt_source_register & _INT_SINGLE_TAP > 0
)
else:
self._event_status[event_type] = (
interrupt_source_register & _INT_DOUBLE_TAP > 0
)
if event_type == "freefall":
self._event_status[event_type] = (
interrupt_source_register & _INT_FREE_FALL > 0
)
return self._event_status
def enable_motion_detection(self, *, threshold=18):
"""
The activity detection parameters.
:param int threshold: The value that acceleration on any axis must exceed to\
register as active. The scale factor is 62.5 mg/LSB.
If you wish to set them yourself rather than using the defaults,
you must use keyword arguments::
accelerometer.enable_motion_detection(threshold=20)
"""
active_interrupts = self._read_register_unpacked(_REG_INT_ENABLE)
self._write_register_byte(_REG_INT_ENABLE, 0x0) # disable interrupts for setup
self._write_register_byte(
_REG_ACT_INACT_CTL, 0b01110000
) # enable activity on X,Y,Z
self._write_register_byte(_REG_THRESH_ACT, threshold)
self._write_register_byte(_REG_INT_ENABLE, _INT_ACT) # Inactive interrupt only
active_interrupts |= _INT_ACT
self._write_register_byte(_REG_INT_ENABLE, active_interrupts)
self._enabled_interrupts["motion"] = True
def disable_motion_detection(self):
"""
Disable motion detection
"""
active_interrupts = self._read_register_unpacked(_REG_INT_ENABLE)
active_interrupts &= ~_INT_ACT
self._write_register_byte(_REG_INT_ENABLE, active_interrupts)
self._enabled_interrupts.pop("motion")
def enable_freefall_detection(self, *, threshold=10, time=25):
"""
Freefall detection parameters:
:param int threshold: The value that acceleration on all axes must be under to\
register as dropped. The scale factor is 62.5 mg/LSB.
:param int time: The amount of time that acceleration on all axes must be less than\
``threshhold`` to register as dropped. The scale factor is 5 ms/LSB. Values between 100 ms\
and 350 ms (20 to 70) are recommended.
If you wish to set them yourself rather than using the defaults,
you must use keyword arguments::
accelerometer.enable_freefall_detection(time=30)
"""
active_interrupts = self._read_register_unpacked(_REG_INT_ENABLE)
self._write_register_byte(_REG_INT_ENABLE, 0x0) # disable interrupts for setup
self._write_register_byte(_REG_THRESH_FF, threshold)
self._write_register_byte(_REG_TIME_FF, time)
# add FREE_FALL to the active interrupts and set them to re-enable
active_interrupts |= _INT_FREE_FALL
self._write_register_byte(_REG_INT_ENABLE, active_interrupts)
self._enabled_interrupts["freefall"] = True
def disable_freefall_detection(self):
"Disable freefall detection"
active_interrupts = self._read_register_unpacked(_REG_INT_ENABLE)
active_interrupts &= ~_INT_FREE_FALL
self._write_register_byte(_REG_INT_ENABLE, active_interrupts)
self._enabled_interrupts.pop("freefall")
def enable_tap_detection(
self, *, tap_count=1, threshold=20, duration=50, latency=20, window=255
): # pylint: disable=line-too-long
"""
The tap detection parameters.
:param int tap_count: 1 to detect only single taps, and 2 to detect only double taps.
:param int threshold: A threshold for the tap detection. The scale factor is 62.5 mg/LSB\
The higher the value the less sensitive the detection.
:param int duration: This caps the duration of the impulse above ``threshhold``.\
Anything above ``duration`` won't register as a tap. The scale factor is 625 µs/LSB
:param int latency(double tap only): The length of time after the initial impulse\
falls below ``threshold`` to start the window looking for a second impulse.\
The scale factor is 1.25 ms/LSB.
:param int window(double tap only): The length of the window in which to look for a\
second tap. The scale factor is 1.25 ms/LSB
If you wish to set them yourself rather than using the defaults,
you must use keyword arguments::
accelerometer.enable_tap_detection(duration=30, threshold=25)
"""
active_interrupts = self._read_register_unpacked(_REG_INT_ENABLE)
self._write_register_byte(_REG_INT_ENABLE, 0x0) # disable interrupts for setup
self._write_register_byte(
_REG_TAP_AXES, 0b00000111
) # enable X, Y, Z axes for tap
self._write_register_byte(_REG_THRESH_TAP, threshold)
self._write_register_byte(_REG_DUR, duration)
if tap_count == 1:
active_interrupts |= _INT_SINGLE_TAP
self._write_register_byte(_REG_INT_ENABLE, active_interrupts)
self._enabled_interrupts["tap"] = 1
elif tap_count == 2:
self._write_register_byte(_REG_LATENT, latency)
self._write_register_byte(_REG_WINDOW, window)
active_interrupts |= _INT_DOUBLE_TAP
self._write_register_byte(_REG_INT_ENABLE, active_interrupts)
self._enabled_interrupts["tap"] = 2
else:
raise ValueError(
"tap must be 0 to disable, 1 for single tap, or 2 for double tap"
)
def disable_tap_detection(self):
"Disable tap detection"
active_interrupts = self._read_register_unpacked(_REG_INT_ENABLE)
active_interrupts &= ~_INT_SINGLE_TAP
active_interrupts &= ~_INT_DOUBLE_TAP
self._write_register_byte(_REG_INT_ENABLE, active_interrupts)
self._enabled_interrupts.pop("tap")
@property
def data_rate(self):
"""The data rate of the sensor."""
rate_register = self._read_register_unpacked(_REG_BW_RATE)
return rate_register & 0x0F
@data_rate.setter
def data_rate(self, val):
self._write_register_byte(_REG_BW_RATE, val)
@property
def range(self):
"""The measurement range of the sensor."""
range_register = self._read_register_unpacked(_REG_DATA_FORMAT)
return range_register & 0x03
@range.setter
def range(self, val):
# read the current value of the data format register
format_register = self._read_register_unpacked(_REG_DATA_FORMAT)
# clear the bottom 4 bits and update the data rate
format_register &= ~0x0F
format_register |= val
# Make sure that the FULL-RES bit is enabled for range scaling
format_register |= 0x08
# write the updated values
self._write_register_byte(_REG_DATA_FORMAT, format_register)
def _read_clear_interrupt_source(self):
return self._read_register_unpacked(_REG_INT_SOURCE)
def _read_register_unpacked(self, register):
return unpack("<b", self._read_register(register, 1))[0]
def _read_register(self, register, length):
self._buffer[0] = register & 0xFF
with self._i2c as i2c:
i2c.write(self._buffer, start=0, end=1)
i2c.readinto(self._buffer, start=0, end=length)
return self._buffer[0:length]
def _write_register_byte(self, register, value):
self._buffer[0] = register & 0xFF
self._buffer[1] = value & 0xFF
with self._i2c as i2c:
i2c.write(self._buffer, start=0, end=2)
class ADXL343(ADXL345):
"""
Stub class for the ADXL343 3-axis accelerometer
"""
Reference in a new issue View git blame Copy permalink