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# ----------------------------------------------------------------------------
# compass_cmps12.py
# Compass based on CMPS12 tilt-compensated compass driver
# For details, see http://www.robot-electronics.co.uk/files/cmps12.pdf
#
# The MIT License (MIT)
# Copyright (c) 2018 Thomas Euler
# 2018-10-30, v1
# 2019-05-06, `getPitchRoll` now returns 4-element tuple, with a -1 at
# position 1 to be compatible with the data format returned
# by `getHeading3D`
# 2019-12-21, native code generation added (requires MicroPython >=1.12)
# ----------------------------------------------------------------------------
try:
import struct
except ImportError:
import ustruct as struct
from math import radians
from micropython import const
from driver.sensor_base import SensorBase
__version__ = "0.1.1.0"
CHIP_NAME = "CMPS12"
# pylint: disable=bad-whitespace
_ADDRESS_CMPS12 = const(0x60) # (0xD0 >> 1)
OK = const(0)
ERR_DEVICE_NOT_READY = const(-1)
# Compass registers
_REG_CMD = const(0x00)
_REG_BEARING_8BIT = const(0x01) # 0-255 for a full circle
_REG_BEARING_16BIT_HB = const(0x02) # 0-3599, w/next
_REG_BEARING_16BIT_LB = const(0x03)
_REG_PITCH_8BIT_ANGLE = const(0x04) # signed byte, +/- 90°
_REG_ROLL_8BIT_ANGLE = const(0x05) # signed byte, +/- 90°
_REG_MAG_X_RAW_HB = const(0x06) # 16 bit signed int, w/next
_REG_MAG_X_RAW_LB = const(0x07)
_REG_MAG_Y_RAW_HB = const(0x08) # 16 bit signed int, w/next
_REG_MAG_Y_RAW_LB = const(0x09)
_REG_MAG_Z_RAW_HB = const(0x0A) # 16 bit signed int, w/next
_REG_MAG_Z_RAW_LB = const(0x0B)
_REG_ACCEL_X_RAW_HB = const(0x0C) # 16 bit signed int, w/next
_REG_ACCEL_X_RAW_LB = const(0x0D)
_REG_ACCEL_Y_RAW_HB = const(0x0E) # 16 bit signed int, w/next
_REG_ACCEL_Y_RAW_LB = const(0x0F)
_REG_ACCEL_Z_RAW_HB = const(0x10) # 16 bit signed int, w/next
_REG_ACCEL_Z_RAW_LB = const(0x11)
_REG_GYRO_X_RAW_HB = const(0x12) # 16 bit signed int, w/next
_REG_GYRO_X_RAW_LB = const(0x13)
_REG_GYRO_Y_RAW_HB = const(0x14) # 16 bit signed int, w/next
_REG_GYRO_Y_RAW_LB = const(0x15)
_REG_GYRO_Z_RAW_HB = const(0x16) # 16 bit signed int, w/next
_REG_GYRO_Z_RAW_LB = const(0x17)
_REG_TEMP_DEG_HB = const(0x18) # in degrees°, w/next
_REG_TEMP_DEG_LB = const(0x19)
_REG_BEARING_16BIT_BNO_HB = const(0x1A) # 0-5759, /16=°, w/next
_REG_BEARING_16BIT_BNO_LB = const(0x1B)
_REG_PITCH_16BIT_ANGLE_HB = const(0x1C) # 16bit signed int, +/- 180°, w/next
_REG_PITCH_16BIT_ANGLE_LB = const(0x1D)
_REG_CALIB_STATE = const(0x1E) # Calibration state, 0=not, 3=fully
# ----------------------------------------------------------------------------
class Compass(SensorBase):
"""Compass class that uses the tilt-compensated CMPS12 breakout."""
def __init__(self, i2c):
""" Requires already initialized I2C bus instance.
"""
super().__init__(None, 0)
self._i2c = i2c
self._isReady = False
self._type = "Compass w/ tilt-compensation"
addrList = self._i2c.deviceAddrList
if (_ADDRESS_CMPS12 in addrList):
# Get version and initialize
buf = bytearray(1)
self._read_bytes(_ADDRESS_CMPS12, _REG_CMD, buf)
self._version = buf[0]
self._heading = 0.0
self._pitch = 0.0
self._roll = 0.0
self._isReady = True
cn = "{0}_v{1}".format(CHIP_NAME, self._version)
print("[{0:>12}] {1:35} ({2}): {3}"
.format(cn, self._type, __version__,
"ok" if self._isReady else "FAILED"))
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
#@timed_function
@micropython.native
def getHeading(self, tilt=False, calib=False, hires=True):
""" Returns heading with or w/o tilt compensation and/or calibration,
if available.
NOTE: The CMPS12 has built-in tilt compensation and is pre-calibra-
ted, therefore the parameters "tilt" and "calib" are only for
compatibility reasons and have no effect. With "hires"=True, the
precision is 3599/360°, otherwise 255/360°.
"""
if not self._isReady:
return ERR_DEVICE_NOT_READY
hd = self._heading
if hires:
buf = bytearray(1)
self._read_bytes(_ADDRESS_CMPS12, _REG_BEARING_8BIT, buf)
hd = buf[0]/255 *360
else:
buf = bytearray(2)
self._read_bytes(_ADDRESS_CMPS12, _REG_BEARING_16BIT_HB, buf)
hd = ((buf[0] << 8) | buf[1]) /10
return hd
#@timed_function
@micropython.native
def getHeading3D(self, calib=False):
""" Returns heading, pitch and roll in [°] with or w/o calibration,
if available.
NOTE: The CMPS12 has built-in tilt compensation and is pre-calibra-
ted, therefore the parameter "calib" exists only for compatibility
reasons and has no effect.
"""
if not self._isReady:
return (ERR_DEVICE_NOT_READY, 0, 0, 0)
hd = self._heading
pit = self._pitch
rol = self._roll
buf = bytearray(4)
self._read_bytes(_ADDRESS_CMPS12, _REG_BEARING_16BIT_HB, buf)
hd, pit, rol = struct.unpack_from('>Hbb', buf[0:4])
hd /= 10
return (OK, hd, pit, rol)
#@timed_function
@micropython.native
def getPitchRoll(self, radians=False):
""" Returns error code, pitch and roll in [°] as a tuple
"""
if not self._isReady:
return (ERR_DEVICE_NOT_READY, 0, 0)
pit = self._pitch
rol = self._roll
buf = bytearray(2)
self._read_bytes(_ADDRESS_CMPS12, _REG_PITCH_8BIT_ANGLE, buf)
pit, rol = struct.unpack_from('>bb', buf[0:2])
if radians:
return (OK, -1, radians(pit), radians(rol))
else:
return (OK, -1, pit, rol)
@property
def isReady(self):
return self._isReady
@property
def channelCount(self):
return CHAN_COUNT
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
def _read_bytes(self, i2cAddr, regAddr, buf):
cmd = bytearray(1)
cmd[0] = regAddr & 0xff
self._i2c.bus.writeto(i2cAddr, cmd, False)
self._i2c.bus.readfrom_into(i2cAddr, buf)
# ----------------------------------------------------------------------------
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