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Commit 3559ce7

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micropython/drivers/imu/BMM150: Add Magnetometer driver.
* BOSCH BMM150 magnetometer.
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"""
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The MIT License (MIT)
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Copyright (c) 2023 Arduino SA
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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Basic example usage:
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import time
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from bmm150 import BMM150
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from machine import Pin, SPI, I2C
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# Init in I2C mode.
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imu = BMM150(I2C(1, scl=Pin(15), sda=Pin(14)))
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# Or init in SPI mode.
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# TODO: Not supported yet.
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# imu = BMM150(SPI(5), cs_pin=Pin(10))
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while (True):
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print('magnetometer: x:{:>8.3f} y:{:>8.3f} z:{:>8.3f}'.format(*imu.read_magnet()))
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time.sleep_ms(100)
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"""
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import array
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import time
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from micropython import const
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class BMM150:
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_DEFAULT_ADDR = const(0x10)
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_CHIP_ID = const(0x40)
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_DATA = const(0x42)
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_POWER = const(0x4B)
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_OPMODE = const(0x4C)
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_INT_STATUS = const(0x4A)
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_TRIM_X1 = const(0x5D)
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_TRIM_Y1 = const(0x5E)
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_TRIM_Z4_LSB = const(0x62)
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_TRIM_Z2_LSB = const(0x68)
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_XYAXES_FLIP = const(-4096)
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_ZHAXES_FLIP = const(-16384)
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def __init__(
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self,
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bus,
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cs_pin=None,
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address=_DEFAULT_ADDR,
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magnet_odr=30,
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):
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"""Initalizes the Magnetometer.
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bus: IMU bus
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address: I2C address (in I2C mode).
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cs_pin: SPI CS pin (in SPI mode).
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magnet_odr: (2, 6, 8, 10, 15, 20, 25, 30)
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"""
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self.bus = bus
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self.cs_pin = cs_pin
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self.address = address
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self._use_i2c = hasattr(self.bus, "readfrom_mem")
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ODR = (10, 2, 6, 8, 15, 20, 25, 30)
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# Sanity checks
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if not self._use_i2c:
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raise ValueError("SPI mode is not supported")
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if not magnet_odr in ODR:
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raise ValueError("Invalid sampling rate: %d" % magnet_odr)
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# Perform soft reset, and power on.
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self.__write_reg(_POWER, 0x83)
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time.sleep_ms(10)
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if self.__read_reg(_CHIP_ID) != 0x32:
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raise OSError("No BMM150 device was found at address 0x%x" % (self.address))
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# Configure the device.
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# ODR | OP: Normal mode
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self.__write_reg(_OPMODE, ODR.index(magnet_odr) << 3)
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# Read trim registers.
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trim_x1y1 = self.__read_reg(_TRIM_X1, 2)
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trim_xyz_data = self.__read_reg(_TRIM_Z4_LSB, 4)
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trim_xy1xy2 = self.__read_reg(_TRIM_Z2_LSB, 10)
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self.trim_x1 = trim_x1y1[0]
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self.trim_y1 = trim_x1y1[1]
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self.trim_x2 = trim_xyz_data[2]
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self.trim_y2 = trim_xyz_data[3]
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self.trim_z1 = (trim_xy1xy2[3] << 8) | trim_xy1xy2[2]
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self.trim_z2 = (trim_xy1xy2[1] << 8) | trim_xy1xy2[0]
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self.trim_z3 = (trim_xy1xy2[7] << 8) | trim_xy1xy2[6]
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self.trim_z4 = (trim_xyz_data[1] << 8) | trim_xyz_data[0]
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self.trim_xy1 = trim_xy1xy2[9]
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self.trim_xy2 = trim_xy1xy2[8]
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self.trim_xyz1 = ((trim_xy1xy2[5] & 0x7F) << 8) | trim_xy1xy2[4]
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# Allocate scratch buffer.
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self.scratch = memoryview(array.array("h", [0, 0, 0, 0]))
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def __read_reg(self, reg, size=1):
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buf = self.bus.readfrom_mem(self.address, reg, size)
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if size == 1:
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return int(buf[0])
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return buf
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def __read_reg_into(self, reg, buf):
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self.bus.readfrom_mem_into(self.address, reg, buf)
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def __write_reg(self, reg, val):
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self.bus.writeto_mem(self.address, reg, bytes([val]))
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def __compensate_x(self, raw, hall):
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"""Compensation equation ported from C driver"""
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x = 0.0
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if raw != _XYAXES_FLIP:
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x0 = self.trim_xyz1 * 16384.0 / hall
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x = x0 - 16384.0
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x1 = (self.trim_xy2) * (x**2 / 268435456.0)
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x2 = x1 + x * (self.trim_xy1) / 16384.0
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x3 = (self.trim_x2) + 160.0
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x4 = raw * ((x2 + 256.0) * x3)
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x = ((x4 / 8192.0) + (self.trim_x1 * 8.0)) / 16.0
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return x
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def __compensate_y(self, raw, hall):
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"""Compensation equation ported from C driver"""
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y = 0.0
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if raw != _XYAXES_FLIP:
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y0 = self.trim_xyz1 * 16384 / hall
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y = y0 - 16384
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y1 = self.trim_xy2 * (y**2 / 268435456)
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y2 = y1 + y * self.trim_xy1 / 16384
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y3 = self.trim_y2 + 160
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y4 = raw * ((y2 + 256) * y3)
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y = ((y4 / 8192) + (self.trim_y1 * 8.0)) / 16.0
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return y
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def __compensate_z(self, raw, hall):
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"""Compensation equation ported from C driver"""
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z = 0.0
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if raw != _ZHAXES_FLIP:
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z0 = raw - self.trim_z4
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z1 = hall - self.trim_xyz1
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z2 = self.trim_z3 * z1
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z3 = (self.trim_z1 * hall) / 32768.0
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z4 = self.trim_z2 + z3
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z5 = (z0 * 131072.0) - z2
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z = (z5 / (z4 * 4.0)) / 16.0
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return z
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def reset(self):
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self.__write_reg(_CMD, 0xB6)
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def read_magnet_raw(self):
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for i in range(0, 10):
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self.__read_reg_into(_DATA, self.scratch)
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if self.scratch[3] & 0x1:
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return (
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self.scratch[0] >> 3,
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self.scratch[1] >> 3,
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self.scratch[2] >> 1,
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self.scratch[3] >> 2,
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)
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time.sleep_ms(30)
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raise OSError("Data not ready")
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def read_magnet(self):
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"""Returns magnetometer vector."""
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x, y, z, h = self.read_magnet_raw()
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return (self.__compensate_x(x, h), self.__compensate_y(y, h), self.__compensate_z(z, h))
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module("bmm150.py", opt=3)
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metadata(description="BOSCH BMM150 magnetometer driver.", version="1.0.0")

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