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| 1 | +# The MIT License (MIT) |
| 2 | +# |
| 3 | +# Copyright (c) 2017 Tony DiCola for Adafruit Industries |
| 4 | +# |
| 5 | +# Permission is hereby granted, free of charge, to any person obtaining a copy |
| 6 | +# of this software and associated documentation files (the "Software"), to deal |
| 7 | +# in the Software without restriction, including without limitation the rights |
| 8 | +# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| 9 | +# copies of the Software, and to permit persons to whom the Software is |
| 10 | +# furnished to do so, subject to the following conditions: |
| 11 | +# |
| 12 | +# The above copyright notice and this permission notice shall be included in |
| 13 | +# all copies or substantial portions of the Software. |
| 14 | +# |
| 15 | +# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 16 | +# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 17 | +# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| 18 | +# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 19 | +# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| 20 | +# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| 21 | +# THE SOFTWARE. |
| 22 | +""" |
| 23 | +`adafruit_fxos8700` |
| 24 | +==================================================== |
| 25 | +
|
| 26 | +CircuitPython module for the NXP FXOS8700 accelerometer and magnetometer. |
| 27 | +Based on the driver from: |
| 28 | + https://github.com/adafruit/Adafruit_FXOS8700 |
| 29 | +
|
| 30 | +See examples/simpletest.py for a demo of the usage. |
| 31 | +
|
| 32 | +* Author(s): Tony DiCola |
| 33 | +""" |
| 34 | +import adafruit_bus_device.i2c_device as i2c_device |
| 35 | + |
| 36 | + |
| 37 | +# Register addresses and other constants: |
| 38 | +_FXOS8700_ADDRESS = const(0x1F) # 0011111 |
| 39 | +_FXOS8700_ID = const(0xC7) # 1100 0111 |
| 40 | +_FXOS8700_REGISTER_STATUS = const(0x00) |
| 41 | +_FXOS8700_REGISTER_OUT_X_MSB = const(0x01) |
| 42 | +_FXOS8700_REGISTER_OUT_X_LSB = const(0x02) |
| 43 | +_FXOS8700_REGISTER_OUT_Y_MSB = const(0x03) |
| 44 | +_FXOS8700_REGISTER_OUT_Y_LSB = const(0x04) |
| 45 | +_FXOS8700_REGISTER_OUT_Z_MSB = const(0x05) |
| 46 | +_FXOS8700_REGISTER_OUT_Z_LSB = const(0x06) |
| 47 | +_FXOS8700_REGISTER_WHO_AM_I = const(0x0D) # 11000111 r |
| 48 | +_FXOS8700_REGISTER_XYZ_DATA_CFG = const(0x0E) |
| 49 | +_FXOS8700_REGISTER_CTRL_REG1 = const(0x2A) # 00000000 r/w |
| 50 | +_FXOS8700_REGISTER_CTRL_REG2 = const(0x2B) # 00000000 r/w |
| 51 | +_FXOS8700_REGISTER_CTRL_REG3 = const(0x2C) # 00000000 r/w |
| 52 | +_FXOS8700_REGISTER_CTRL_REG4 = const(0x2D) # 00000000 r/w |
| 53 | +_FXOS8700_REGISTER_CTRL_REG5 = const(0x2E) # 00000000 r/w |
| 54 | +_FXOS8700_REGISTER_MSTATUS = const(0x32) |
| 55 | +_FXOS8700_REGISTER_MOUT_X_MSB = const(0x33) |
| 56 | +_FXOS8700_REGISTER_MOUT_X_LSB = const(0x34) |
| 57 | +_FXOS8700_REGISTER_MOUT_Y_MSB = const(0x35) |
| 58 | +_FXOS8700_REGISTER_MOUT_Y_LSB = const(0x36) |
| 59 | +_FXOS8700_REGISTER_MOUT_Z_MSB = const(0x37) |
| 60 | +_FXOS8700_REGISTER_MOUT_Z_LSB = const(0x38) |
| 61 | +_FXOS8700_REGISTER_MCTRL_REG1 = const(0x5B) # 00000000 r/w |
| 62 | +_FXOS8700_REGISTER_MCTRL_REG2 = const(0x5C) # 00000000 r/w |
| 63 | +_FXOS8700_REGISTER_MCTRL_REG3 = const(0x5D) # 00000000 r/w |
| 64 | +_ACCEL_MG_LSB_2G = 0.000244 |
| 65 | +_ACCEL_MG_LSB_4G = 0.000488 |
| 66 | +_ACCEL_MG_LSB_8G = 0.000976 |
| 67 | +_MAG_UT_LSB = 0.1 |
| 68 | +_SENSORS_GRAVITY_STANDARD = 9.80665 |
| 69 | + |
| 70 | +# User-facing constants/module-level globals: |
| 71 | +ACCEL_RANGE_2G = 0x00 |
| 72 | +ACCEL_RANGE_4G = 0x01 |
| 73 | +ACCEL_RANGE_8G = 0x02 |
| 74 | + |
| 75 | + |
| 76 | +class FXOS8700: |
| 77 | + |
| 78 | + # Class-level buffer for reading and writing data with the sensor. |
| 79 | + # This reduces memory allocations but means the code is not re-entrant or |
| 80 | + # thread safe! |
| 81 | + _BUFFER = bytearray(13) |
| 82 | + |
| 83 | + def __init__(self, i2c, address=_FXOS8700_ADDRESS, |
| 84 | + accel_range=ACCEL_RANGE_2G): |
| 85 | + assert accel_range in (ACCEL_RANGE_2G, ACCEL_RANGE_4G, ACCEL_RANGE_8G) |
| 86 | + self._accel_range = accel_range |
| 87 | + self._device = i2c_device.I2CDevice(i2c, address) |
| 88 | + # Check for chip ID value. |
| 89 | + if self._read_u8(_FXOS8700_REGISTER_WHO_AM_I) != _FXOS8700_ID: |
| 90 | + raise RuntimeError('Failed to find FXOS8700, check wiring!') |
| 91 | + # Set to standby mode (required to make changes to this register) |
| 92 | + self._write_u8(_FXOS8700_REGISTER_CTRL_REG1, 0) |
| 93 | + if accel_range == ACCEL_RANGE_2G: |
| 94 | + self._write_u8(_FXOS8700_REGISTER_XYZ_DATA_CFG, 0x00) |
| 95 | + elif accel_range == ACCEL_RANGE_4G: |
| 96 | + self._write_u8(_FXOS8700_REGISTER_XYZ_DATA_CFG, 0x01) |
| 97 | + elif accel_range == ACCEL_RANGE_8G: |
| 98 | + self._write_u8(_FXOS8700_REGISTER_XYZ_DATA_CFG, 0x02) |
| 99 | + # High resolution |
| 100 | + self._write_u8(_FXOS8700_REGISTER_CTRL_REG2, 0x02) |
| 101 | + # Active, Normal Mode, Low Noise, 100Hz in Hybrid Mode |
| 102 | + self._write_u8(_FXOS8700_REGISTER_CTRL_REG1, 0x15) |
| 103 | + # Configure the magnetometer |
| 104 | + # Hybrid Mode, Over Sampling Rate = 16 |
| 105 | + self._write_u8(_FXOS8700_REGISTER_MCTRL_REG1, 0x1F) |
| 106 | + # Jump to reg 0x33 after reading 0x06 |
| 107 | + self._write_u8(_FXOS8700_REGISTER_MCTRL_REG2, 0x20) |
| 108 | + |
| 109 | + def _read_u8(self, address): |
| 110 | + # Read an 8-bit unsigned value from the specified 8-bit address. |
| 111 | + with self._device: |
| 112 | + self._BUFFER[0] = address & 0xFF |
| 113 | + self._device.write(self._BUFFER, end=1) |
| 114 | + self._device.readinto(self._BUFFER, end=1) |
| 115 | + return self._BUFFER[0] |
| 116 | + |
| 117 | + def _write_u8(self, address, val): |
| 118 | + # Write an 8-bit unsigned value to the specified 8-bit address. |
| 119 | + with self._device: |
| 120 | + self._BUFFER[0] = address & 0xFF |
| 121 | + self._BUFFER[1] = val & 0xFF |
| 122 | + self._device.write(self._BUFFER, end=2) |
| 123 | + |
| 124 | + def read_raw_accel_mag(self): |
| 125 | + """Read the raw accelerometer and magnetometer readings. Returns a |
| 126 | + 2-tuple of 3-tuples: |
| 127 | + - Accelerometer X, Y, Z axis 14-bit unsigned raw values |
| 128 | + - Magnetometer X, Y, Z axis 16-bit unsigned raw values |
| 129 | + If you want the acceleration or magnetometer values in friendly units |
| 130 | + consider using the accelerometer and magnetometer properties! |
| 131 | + """ |
| 132 | + # Read 13 bytes from the sensor. |
| 133 | + with self._device: |
| 134 | + self._BUFFER[0] = _FXOS8700_REGISTER_STATUS | 0x80 |
| 135 | + self._device.write(self._BUFFER, end=1) |
| 136 | + self._device.readinto(self._BUFFER) |
| 137 | + # Parse out the accelerometer and magnetometer data. |
| 138 | + status = self._BUFFER[0] |
| 139 | + axhi = self._BUFFER[1] |
| 140 | + axlo = self._BUFFER[2] |
| 141 | + ayhi = self._BUFFER[3] |
| 142 | + aylo = self._BUFFER[4] |
| 143 | + azhi = self._BUFFER[5] |
| 144 | + azlo = self._BUFFER[6] |
| 145 | + mxhi = self._BUFFER[7] |
| 146 | + mxlo = self._BUFFER[8] |
| 147 | + myhi = self._BUFFER[9] |
| 148 | + mylo = self._BUFFER[10] |
| 149 | + mzhi = self._BUFFER[11] |
| 150 | + mzlo = self._BUFFER[12] |
| 151 | + # Shift values to create properly formed integers |
| 152 | + # Note, accel data is 14-bit and left-aligned, so we shift two bit right |
| 153 | + accel_raw_x = (((axhi << 8) | axlo) >> 2) & 0xFFFF |
| 154 | + accel_raw_y = (((ayhi << 8) | aylo) >> 2) & 0xFFFF |
| 155 | + accel_raw_z = (((azhi << 8) | azlo) >> 2) & 0xFFFF |
| 156 | + mag_raw_x = ((mxhi << 8) | mxlo) & 0xFFFF |
| 157 | + mag_raw_y = ((myhi << 8) | mylo) & 0xFFFF |
| 158 | + mag_raw_z = ((mzhi << 8) | mzlo) & 0xFFFF |
| 159 | + return ((accel_raw_x, accel_raw_y, accel_raw_z), |
| 160 | + (mag_raw_x, mag_raw_y, mag_raw_z)) |
| 161 | + |
| 162 | + @property |
| 163 | + def accelerometer(self): |
| 164 | + """Read the acceleration from the accelerometer and return its |
| 165 | + X, Y, Z axis values as a 3-tuple in m/s^2. |
| 166 | + """ |
| 167 | + accel_raw, mag_raw = self.read_raw_accel_mag() |
| 168 | + # Convert accel values to m/s^2 |
| 169 | + if self._accel_range == ACCEL_RANGE_2G: |
| 170 | + return map(lambda x: x * _ACCEL_MG_LSB_2G * _SENSORS_GRAVITY_STANDARD, |
| 171 | + accel_raw) |
| 172 | + elif self._accel_range == ACCEL_RANGE_4G: |
| 173 | + return map(lambda x: x * _ACCEL_MG_LSB_4G * _SENSORS_GRAVITY_STANDARD, |
| 174 | + accel_raw) |
| 175 | + elif self._accel_range == ACCEL_RANGE_8G: |
| 176 | + return map(lambda x: x * _ACCEL_MG_LSB_8G * _SENSORS_GRAVITY_STANDARD, |
| 177 | + accel_raw) |
| 178 | + |
| 179 | + @property |
| 180 | + def magnetometer(self): |
| 181 | + """Read the magnetometer values and return its X, Y, Z axis values |
| 182 | + as a 3-tuple in uTeslas. |
| 183 | + """ |
| 184 | + accel_raw, mag_raw = self.read_raw_accel_mag() |
| 185 | + # Convert mag values to uTesla |
| 186 | + return map(lambda x: x * _MAG_UT_LSB, mag_raw) |
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