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roboticsmasters_ak8963.py
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roboticsmasters_ak8963.py
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# The MIT License (MIT)
#
# Copyright (c) 2020 Cian Byrne for Robotics Masters Limited
#
# 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.
"""
`roboticsmasters_mpu9250`
================================================================================
CircuitPython helper library for MPU9250 9-axis IMU
* Author(s): Cian Byrne
Implementation Notes
--------------------
**Hardware:**
.. todo:: Add links to any specific hardware product page(s), or category page(s). Use unordered list & hyperlink rST
inline format: "* `Link Text <url>`_"
**Software and Dependencies:**
* Adafruit CircuitPython firmware for the supported boards:
https://github.com/adafruit/circuitpython/releases
.. todo:: Uncomment or remove the Bus Device and/or the Register library dependencies based on the library's use of either.
# * Adafruit's Bus Device library: https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
# * Adafruit's Register library: https://github.com/adafruit/Adafruit_CircuitPython_Register
"""
from time import sleep
from adafruit_register.i2c_struct import UnaryStruct, ROUnaryStruct
from adafruit_register.i2c_struct_array import StructArray
from adafruit_register.i2c_bit import RWBit
from adafruit_register.i2c_bits import RWBits
import adafruit_bus_device.i2c_device as i2c_device
try:
import struct
except ImportError:
import ustruct as struct
from micropython import const
__version__ = "0.0.0-auto.0"
__repo__ = "https://github.com/wallarug/CircuitPython_MPU9250.git"
# pylint: disable=bad-whitespace
_AK8963_DEFAULT_ADDRESS = 0x0c # AK8963 default i2c address
_AK8963_DEVICE_ID = 0x48 # MPU9250 WHO_AM_I value
_AK8963_WIA = 0x00 # Device ID register
_AK8963_INFO = 0x01 # Device Information register
_AK8963_ST1 = 0x02 # Status register 1
_AK8963_MAG_OUT = 0x03 # base address for sensor data reads
_AK8963_HXL = 0x03 #
_AK8963_HXH = 0x04
_AK8963_HYL = 0x05
_AK8963_HYH = 0x06
_AK8963_HZL = 0x07
_AK8963_HZH = 0x08
_AK8963_ST2 = 0x09
_AK8963_CNTL1 = 0x0A # control register 1
_AK8963_CNTL2 = 0x0B # control register 2
_AK8963_ADJUST = 0x10 # base address for sensor adjust reads
_AK8963_ASAX = 0x10
_AK8963_ASAY = 0x11
_AK8963_ASAZ = 0x12
class Sensitivity:
"""Allowed values for `range`.
- ``Rate.CYCLE_1_25_HZ``
- ``Rate.CYCLE_5_HZ``
- ``Rate.CYCLE_20_HZ``
- ``Rate.CYCLE_40_HZ``
"""
SENSE_14BIT = 0
SENSE_16BIT = 1
class Mode:
"""Allowed values for `mode` setting
- ``Mode.MODE_POWERDOWN``
- ``Mode.MODE_SINGLE``
- ``Mode.MODE_CONT1``
- ``Mode.MODE_CONT2``
- ``Mode.MODE_EXT_TRIG``
- ``Mode.MODE_SELFTEST``
- ``Mode.MODE_FUSE``
"""
POWERDOWN = 0 #0b0000
MEASURE_SINGLE = 1 #0b0001
MEASURE_8HZ = 2 #0b0010 # 8 Hz (mode 1)
EXT_TRIG = 4 #0b0100
MEASURE_100HZ = 5 #0b0110 # 100 Hz (mode 2)
SELFTEST = 8 #0b1000
FUSE = 15 #0b1111
def _twos_comp(val, bits):
# Convert an unsigned integer in 2's compliment form of the specified bit
# length to its signed integer value and return it.
if val & (1 << (bits - 1)) != 0:
return val - (1 << bits)
return val
class AK8963:
"""Driver for the AK8963 magnetometer.
:param ~busio.I2C i2c_bus: The I2C bus the AK8963 is connected to.
:param address: The I2C slave address of the sensor
"""
def __init__(self, i2c_bus, address=_AK8963_DEFAULT_ADDRESS):
self.i2c_device = i2c_device.I2CDevice(i2c_bus, address)
if self._device_id != _AK8963_DEVICE_ID:
raise RuntimeError("Failed to find AKM8963 - check your wiring!")
self.reset()
self._mode = Mode.FUSE
raw_adjustment = self._raw_adjustment_data
self. _mode = Mode.POWERDOWN
sleep(0.100)
asax = raw_adjustment[0][0]
asay = raw_adjustment[1][0]
asaz = raw_adjustment[2][0]
print(asax, asay, asaz)
self._offset = (143.725, 6.00244, -21.6755)
self._scale = (1.07464, 0.97619, 0.956875)
self._adjustment = (
((asax - 128.0) / 256.0) + 1.0,
((asay - 128.0) / 256.0) + 1.0,
((asaz - 128.0) / 256.0) + 1.0
)
print(self._adjustment)
self._mag_range = Sensitivity.SENSE_16BIT
self._mode = Mode.MEASURE_8HZ
sleep(0.100)
def reset(self):
"""Reinitialize the sensor"""
self._reset = True
while self._reset is True:
sleep(0.001)
sleep(0.100)
def start(self):
"""Start Up and Initalise the sensor"""
_mag_range = Sensitivity.SENSE_16BIT
_mode = Mode.MEASURE_8HZ
_device_id = ROUnaryStruct(_AK8963_WIA, ">B")
_reset = RWBit(_AK8963_CNTL2, 0, 1)
_raw_magnet_data = StructArray(_AK8963_MAG_OUT, "<h", 3)
_raw_adjustment_data = StructArray(_AK8963_ADJUST, "<B", 3)
_mode = RWBits(4, _AK8963_CNTL1, 0, 1)
_mag_range = RWBit(_AK8963_CNTL1, 4, 1)
_status = ROUnaryStruct(_AK8963_ST2, ">B")
@property
def magnetic(self):
"""The magnetometer X, Y, Z axis values as a 3-tuple of
gauss values.
"""
raw_data = self._raw_magnet_data
#raw_x = _twos_comp(raw_data[0][0], 16)
#raw_y = _twos_comp(raw_data[1][0], 16)
#raw_z = _twos_comp(raw_data[2][0], 16)
raw_x = raw_data[0][0]
raw_y = raw_data[1][0]
raw_z = raw_data[2][0]
print(raw_x, raw_y, raw_z)
self._status # Enable updating readings again
# Apply factory axial sensitivy adjustments
#raw_x *= self._adjustment[0]
#raw_y *= self._adjustment[1]
#raw_z *= self._adjustment[2]
# Apply output scale determined in constructor
mag_range = self._mag_range
mag_scale = 1
if mag_range == Sensitivity.SENSE_16BIT:
#mag_scale = 0.15 - for uT (micro-tesla)
mag_scale = 1.499389499 # for mG (milliGauss) calc: 10.*4912./32760.0
if mag_range == Sensitivity.SENSE_14BIT:
#mag_scale = 0.6 - for uT (mico-tesla)
mag_scale = 5.997557998 # for mG (millGauss) calc: 10.*4912./8190.0
# setup range dependant scaling and offsets
#mag_x = ((raw_x / mag_scale) - self._offset[0]) * self._scale[0]
#mag_y = ((raw_y / mag_scale) - self._offset[1]) * self._scale[1]
#mag_z = ((raw_z / mag_scale) - self._offset[2]) * self._scale[2]
mag_x = (raw_x * mag_scale * self._scale[0]) - self._offset[0]
mag_y = (raw_y * mag_scale * self._scale[1]) - self._offset[1]
mag_z = (raw_z * mag_scale * self._scale[2]) - self._offset[1]
return (mag_x, mag_y, mag_z)
def calibrate(self, count=256, delay=0.200):
"""
Calibrate the magnetometer.
The magnetometer needs to be turned in all possible directions
during the callibration process. Ideally each axis would once
line up with the magnetic field.
count: int
Number of magnetometer readings that are taken for the calibration.
delay: float
Delay between the magntometer readings in seconds.
"""
print("Starting Calibration.")
print("The magnetometer needs to be turned in all possible directions \
during the callibration process. Ideally each axis would once \
line up with the magnetic field.")
self._offset = (0, 0, 0)
self._scale = (1, 1, 1)
raw_data = self._raw_magnet_data
raw_x = raw_data[0][0]
raw_y = raw_data[1][0]
raw_z = raw_data[2][0]
self._status # Enable updating readings again
minx = maxx = raw_x
miny = maxy = raw_y
minz = maxz = raw_z
while count:
sleep(delay)
raw_data = self._raw_magnet_data
print(raw_x, raw_y, raw_z)
raw_x = raw_data[0][0]
raw_y = raw_data[1][0]
raw_z = raw_data[2][0]
self._status # Enable updating readings again
minx = min(minx, raw_x)
maxx = max(maxx, raw_x)
miny = min(miny, raw_y)
maxy = max(maxy, raw_y)
minz = min(minz, raw_z)
maxz = max(maxz, raw_z)
count -= 1
# Hard iron correction
offset_x = (maxx + minx) / 2
offset_y = (maxy + miny) / 2
offset_z = (maxz + minz) / 2
self._offset = (offset_x, offset_y, offset_z)
print("+++++++++++")
print("Hard Iron Offset Values:")
print(self._offset)
# Soft iron correction
avg_delta_x = (maxx - minx) / 2
avg_delta_y = (maxy - miny) / 2
avg_delta_z = (maxz - minz) / 2
avg_delta = (avg_delta_x + avg_delta_y + avg_delta_z) / 3
scale_x = avg_delta / avg_delta_x
scale_y = avg_delta / avg_delta_y
scale_z = avg_delta / avg_delta_z
self._scale = (scale_x, scale_y, scale_z)
print("Soft iron values")
print(self._scale)