Source code for adafruit_lsm303dlh_mag

# SPDX-FileCopyrightText: 2019 Bryan Siepert for Adafruit Industries
#
# SPDX-License-Identifier: MIT

"""
`adafruit_lsm303dlh_mag`
====================================================


CircuitPython driver for the LSM303DLH's magnetometer.

* Author(s): Dave Astels, Bryan Siepert

Implementation Notes
--------------------

**Hardware:**

* Adafruit `Triple-axis Accelerometer+Magnetometer (Compass) Board - LSM303
  <https://www.adafruit.com/product/1120>`_ (Product ID: 1120)
* Adafruit `FLORA Accelerometer/Compass Sensor - LSM303 - v1.0
  <https://www.adafruit.com/product/1247>`_ (Product ID: 1247)

**Software and Dependencies:**

* Adafruit CircuitPython firmware:
  https://circuitpython.org/downloads
* Adafruit's Bus Device library:
  https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
"""

try:
    import struct
except ImportError:
    import ustruct as struct
from micropython import const
from adafruit_bus_device.i2c_device import I2CDevice

__version__ = "0.0.0-auto.0"
__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_LSM303DLH_Mag.git"

_ADDRESS_MAG = const(0x1E)  # (0x3C >> 1)       // 0011110x
_ID = const(0xD4)  # (0b11010100)

# Magnetometer registers
_REG_MAG_CRA_REG_M = const(0x00)
_REG_MAG_CRB_REG_M = const(0x01)
_REG_MAG_MR_REG_M = const(0x02)
_REG_MAG_OUT_X_H_M = const(0x03)
_REG_MAG_OUT_X_L_M = const(0x04)
_REG_MAG_OUT_Z_H_M = const(0x05)
_REG_MAG_OUT_Z_L_M = const(0x06)
_REG_MAG_OUT_Y_H_M = const(0x07)
_REG_MAG_OUT_Y_L_M = const(0x08)
_REG_MAG_SR_REG_M = const(0x09)
_REG_MAG_IRA_REG_M = const(0x0A)
_REG_MAG_IRB_REG_M = const(0x0B)
_REG_MAG_IRC_REG_M = const(0x0C)

_REG_MAG_TEMP_OUT_H_M = const(0x31)
_REG_MAG_TEMP_OUT_L_M = const(0x32)


MAG_DEVICE_ID = 0b01000000
# Magnetometer gains
MAGGAIN_1_3 = const(0x20)  # +/- 1.3
MAGGAIN_1_9 = const(0x40)  # +/- 1.9
MAGGAIN_2_5 = const(0x60)  # +/- 2.5
MAGGAIN_4_0 = const(0x80)  # +/- 4.0
MAGGAIN_4_7 = const(0xA0)  # +/- 4.7
MAGGAIN_5_6 = const(0xC0)  # +/- 5.6
MAGGAIN_8_1 = const(0xE0)  # +/- 8.1

# Magentometer rates
MAGRATE_0_7 = const(0x00)  # 0.75 Hz
MAGRATE_1_5 = const(0x01)  # 1.5 Hz
MAGRATE_3_0 = const(0x02)  # 3.0 Hz
MAGRATE_7_5 = const(0x03)  # 7.5 Hz
MAGRATE_15 = const(0x04)  # 15 Hz
MAGRATE_30 = const(0x05)  # 30 Hz
MAGRATE_75 = const(0x06)  # 75 Hz
MAGRATE_220 = const(0x07)  # 220 Hz

# Conversion constants
_GRAVITY_STANDARD = 9.80665  # Earth's gravity in m/s^2
_GAUSS_TO_MICROTESLA = 100.0  # Gauss to micro-Tesla multiplier


[docs]class LSM303DLH_Mag: """Driver for the Driver for the LSM303DLH's 'magnetometer. :param ~busio.I2C i2c: The I2C bus the device is connected to. **Quickstart: Importing and using the device** Here is an example of using the :class:`LSM303DLH_Mag` class. First you will need to import the libraries to use the sensor .. code-block:: python import board import adafruit_lsm303dlh_mag Once this is done you can define your `board.I2C` object and define your sensor object .. code-block:: python i2c = board.I2C() # uses board.SCL and board.SDA sensor = adafruit_lsm303dlh_mag.LSM303DLH_Mag(i2c) Now you have access to the :attr:`magnetic` attribute .. code-block:: python mag_x, mag_y, mag_z = sensor.magnetic """ # Class-level buffer for reading and writing data with the sensor. # This reduces memory allocations but means the code is not re-entrant or # thread safe! _BUFFER = bytearray(6) def __init__(self, i2c): self._mag_device = I2CDevice(i2c, _ADDRESS_MAG) self._write_u8( self._mag_device, _REG_MAG_MR_REG_M, 0x00 ) # Enable the magnetometer self._lsm303mag_gauss_lsb_xy = 1100.0 self._lsm303mag_gauss_lsb_z = 980.0 self._mag_gain = MAGGAIN_1_3 self._mag_rate = MAGRATE_0_7 @property def _raw_magnetic(self): """The raw magnetometer sensor values. A 3-tuple of X, Y, Z axis values that are 16-bit signed integers. """ self._read_bytes(self._mag_device, _REG_MAG_OUT_X_H_M, 6, self._BUFFER) raw_values = struct.unpack_from(">hhh", self._BUFFER[0:6]) return (raw_values[0], raw_values[2], raw_values[1]) @property def magnetic(self): """The processed magnetometer sensor values. A 3-tuple of X, Y, Z axis values in microteslas that are signed floats. """ mag_x, mag_y, mag_z = self._raw_magnetic return ( mag_x / self._lsm303mag_gauss_lsb_xy * _GAUSS_TO_MICROTESLA, mag_y / self._lsm303mag_gauss_lsb_xy * _GAUSS_TO_MICROTESLA, mag_z / self._lsm303mag_gauss_lsb_z * _GAUSS_TO_MICROTESLA, ) @property def mag_gain(self): """The magnetometer's gain.""" return self._mag_gain @mag_gain.setter def mag_gain(self, value): assert value in ( MAGGAIN_1_3, MAGGAIN_1_9, MAGGAIN_2_5, MAGGAIN_4_0, MAGGAIN_4_7, MAGGAIN_5_6, MAGGAIN_8_1, ) self._mag_gain = value self._write_u8(self._mag_device, _REG_MAG_CRB_REG_M, self._mag_gain) if self._mag_gain == MAGGAIN_1_3: self._lsm303mag_gauss_lsb_xy = 1100.0 self._lsm303mag_gauss_lsb_z = 980.0 elif self._mag_gain == MAGGAIN_1_9: self._lsm303mag_gauss_lsb_xy = 855.0 self._lsm303mag_gauss_lsb_z = 760.0 elif self._mag_gain == MAGGAIN_2_5: self._lsm303mag_gauss_lsb_xy = 670.0 self._lsm303mag_gauss_lsb_z = 600.0 elif self._mag_gain == MAGGAIN_4_0: self._lsm303mag_gauss_lsb_xy = 450.0 self._lsm303mag_gauss_lsb_z = 400.0 elif self._mag_gain == MAGGAIN_4_7: self._lsm303mag_gauss_lsb_xy = 400.0 self._lsm303mag_gauss_lsb_z = 355.0 elif self._mag_gain == MAGGAIN_5_6: self._lsm303mag_gauss_lsb_xy = 330.0 self._lsm303mag_gauss_lsb_z = 295.0 elif self._mag_gain == MAGGAIN_8_1: self._lsm303mag_gauss_lsb_xy = 230.0 self._lsm303mag_gauss_lsb_z = 205.0 @property def mag_rate(self): """The magnetometer update rate.""" return self._mag_rate @mag_rate.setter def mag_rate(self, value): assert value in ( MAGRATE_0_7, MAGRATE_1_5, MAGRATE_3_0, MAGRATE_7_5, MAGRATE_15, MAGRATE_30, MAGRATE_75, MAGRATE_220, ) self._mag_rate = value reg_m = ((value & 0x07) << 2) & 0xFF self._write_u8(self._mag_device, _REG_MAG_CRA_REG_M, reg_m) def _read_u8(self, device, address): with device as i2c: self._BUFFER[0] = address & 0xFF i2c.write_then_readinto(self._BUFFER, self._BUFFER, out_end=1, in_end=1) return self._BUFFER[0] def _write_u8(self, device, address, val): with device as i2c: self._BUFFER[0] = address & 0xFF self._BUFFER[1] = val & 0xFF i2c.write(self._BUFFER, end=2) @staticmethod def _read_bytes(device, address, count, buf): with device as i2c: buf[0] = address & 0xFF i2c.write_then_readinto(buf, buf, out_end=1, in_end=count)