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mpu6500.py
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mpu6500.py
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# Copyright (c) 2018-2020 Mika Tuupola
#
# 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 copied 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.
# https://github.com/tuupola/micropython-mpu9250
"""
MicroPython I2C driver for MPU6500 6-axis motion tracking device
"""
__version__ = "0.3.0"
# pylint: disable=import-error
import ustruct
import utime
from machine import I2C, Pin
from micropython import const
# pylint: enable=import-error
_GYRO_CONFIG = const(0x1b)
_ACCEL_CONFIG = const(0x1c)
_ACCEL_CONFIG2 = const(0x1d)
_ACCEL_XOUT_H = const(0x3b)
_ACCEL_XOUT_L = const(0x3c)
_ACCEL_YOUT_H = const(0x3d)
_ACCEL_YOUT_L = const(0x3e)
_ACCEL_ZOUT_H = const(0x3f)
_ACCEL_ZOUT_L= const(0x40)
_TEMP_OUT_H = const(0x41)
_TEMP_OUT_L = const(0x42)
_GYRO_XOUT_H = const(0x43)
_GYRO_XOUT_L = const(0x44)
_GYRO_YOUT_H = const(0x45)
_GYRO_YOUT_L = const(0x46)
_GYRO_ZOUT_H = const(0x47)
_GYRO_ZOUT_L = const(0x48)
_WHO_AM_I = const(0x75)
#_ACCEL_FS_MASK = const(0b00011000)
ACCEL_FS_SEL_2G = const(0b00000000)
ACCEL_FS_SEL_4G = const(0b00001000)
ACCEL_FS_SEL_8G = const(0b00010000)
ACCEL_FS_SEL_16G = const(0b00011000)
_ACCEL_SO_2G = 16384 # 1 / 16384 ie. 0.061 mg / digit
_ACCEL_SO_4G = 8192 # 1 / 8192 ie. 0.122 mg / digit
_ACCEL_SO_8G = 4096 # 1 / 4096 ie. 0.244 mg / digit
_ACCEL_SO_16G = 2048 # 1 / 2048 ie. 0.488 mg / digit
#_GYRO_FS_MASK = const(0b00011000)
GYRO_FS_SEL_250DPS = const(0b00000000)
GYRO_FS_SEL_500DPS = const(0b00001000)
GYRO_FS_SEL_1000DPS = const(0b00010000)
GYRO_FS_SEL_2000DPS = const(0b00011000)
_GYRO_SO_250DPS = 131
_GYRO_SO_500DPS = 62.5
_GYRO_SO_1000DPS = 32.8
_GYRO_SO_2000DPS = 16.4
_TEMP_SO = 333.87
_TEMP_OFFSET = 21
SF_G = 1
SF_M_S2 = 9.80665 # 1 g = 9.80665 m/s2 ie. standard gravity
SF_DEG_S = 1
SF_RAD_S = 0.017453292519943 # 1 deg/s is 0.017453292519943 rad/s
class MPU6500:
"""Class which provides interface to MPU6500 6-axis motion tracking device."""
def __init__(
self, i2c, address=0x68,
accel_fs=ACCEL_FS_SEL_2G, gyro_fs=GYRO_FS_SEL_250DPS,
accel_sf=SF_M_S2, gyro_sf=SF_RAD_S,
gyro_offset=(0, 0, 0)
):
self.i2c = i2c
self.address = address
# 0x70 = standalone MPU6500, 0x71 = MPU6250 SIP
if self.whoami not in [0x71, 0x70]:
raise RuntimeError("MPU6500 not found in I2C bus.")
self._accel_so = self._accel_fs(accel_fs)
self._gyro_so = self._gyro_fs(gyro_fs)
self._accel_sf = accel_sf
self._gyro_sf = gyro_sf
self._gyro_offset = gyro_offset
@property
def acceleration(self):
"""
Acceleration measured by the sensor. By default will return a
3-tuple of X, Y, Z axis acceleration values in m/s^2 as floats. Will
return values in g if constructor was provided `accel_sf=SF_M_S2`
parameter.
"""
so = self._accel_so
sf = self._accel_sf
xyz = self._register_three_shorts(_ACCEL_XOUT_H)
return tuple([value / so * sf for value in xyz])
@property
def gyro(self):
"""
X, Y, Z radians per second as floats.
"""
so = self._gyro_so
sf = self._gyro_sf
ox, oy, oz = self._gyro_offset
xyz = self._register_three_shorts(_GYRO_XOUT_H)
xyz = [value / so * sf for value in xyz]
xyz[0] -= ox
xyz[1] -= oy
xyz[2] -= oz
return tuple(xyz)
@property
def temperature(self):
"""
Die temperature in celcius as a float.
"""
temp = self._register_short(_TEMP_OUT_H)
return ((temp - _TEMP_OFFSET) / _TEMP_SO) + _TEMP_OFFSET
@property
def whoami(self):
""" Value of the whoami register. """
return self._register_char(_WHO_AM_I)
def calibrate(self, count=256, delay=0):
ox, oy, oz = (0.0, 0.0, 0.0)
self._gyro_offset = (0.0, 0.0, 0.0)
n = float(count)
while count:
utime.sleep_ms(delay)
gx, gy, gz = self.gyro
ox += gx
oy += gy
oz += gz
count -= 1
self._gyro_offset = (ox / n, oy / n, oz / n)
return self._gyro_offset
def _register_short(self, register, value=None, buf=bytearray(2)):
if value is None:
self.i2c.readfrom_mem_into(self.address, register, buf)
return ustruct.unpack(">h", buf)[0]
ustruct.pack_into(">h", buf, 0, value)
return self.i2c.writeto_mem(self.address, register, buf)
def _register_three_shorts(self, register, buf=bytearray(6)):
self.i2c.readfrom_mem_into(self.address, register, buf)
return ustruct.unpack(">hhh", buf)
def _register_char(self, register, value=None, buf=bytearray(1)):
if value is None:
self.i2c.readfrom_mem_into(self.address, register, buf)
return buf[0]
ustruct.pack_into("<b", buf, 0, value)
return self.i2c.writeto_mem(self.address, register, buf)
def _accel_fs(self, value):
self._register_char(_ACCEL_CONFIG, value)
# Return the sensitivity divider
if ACCEL_FS_SEL_2G == value:
return _ACCEL_SO_2G
elif ACCEL_FS_SEL_4G == value:
return _ACCEL_SO_4G
elif ACCEL_FS_SEL_8G == value:
return _ACCEL_SO_8G
elif ACCEL_FS_SEL_16G == value:
return _ACCEL_SO_16G
def _gyro_fs(self, value):
self._register_char(_GYRO_CONFIG, value)
# Return the sensitivity divider
if GYRO_FS_SEL_250DPS == value:
return _GYRO_SO_250DPS
elif GYRO_FS_SEL_500DPS == value:
return _GYRO_SO_500DPS
elif GYRO_FS_SEL_1000DPS == value:
return _GYRO_SO_1000DPS
elif GYRO_FS_SEL_2000DPS == value:
return _GYRO_SO_2000DPS
def __enter__(self):
return self
def __exit__(self, exception_type, exception_value, traceback):
pass