Initial commit.

Author: tdicola

Adafruit_LSM303/LSM303.py

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+# The MIT License (MIT)
+#
+# Copyright (c) 2016 Adafruit Industries
+#
+# 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
+# copies 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.
+import struct
+
+
+# Minimal constants carried over from Arduino library:
+LSM303_ADDRESS_ACCEL = (0x32 >> 1)  # 0011001x
+LSM303_ADDRESS_MAG   = (0x3C >> 1)  # 0011110x
+                                         # Default    Type
+LSM303_REGISTER_ACCEL_CTRL_REG1_A = 0x20 # 00000111   rw
+LSM303_REGISTER_ACCEL_CTRL_REG4_A = 0x23 # 00000000   rw
+LSM303_REGISTER_ACCEL_OUT_X_L_A   = 0x28
+LSM303_REGISTER_MAG_CRB_REG_M     = 0x01
+LSM303_REGISTER_MAG_MR_REG_M      = 0x02
+LSM303_REGISTER_MAG_OUT_X_H_M     = 0x03
+
+# Gain settings for set_mag_gain()
+LSM303_MAGGAIN_1_3 = 0x20 # +/- 1.3
+LSM303_MAGGAIN_1_9 = 0x40 # +/- 1.9
+LSM303_MAGGAIN_2_5 = 0x60 # +/- 2.5
+LSM303_MAGGAIN_4_0 = 0x80 # +/- 4.0
+LSM303_MAGGAIN_4_7 = 0xA0 # +/- 4.7
+LSM303_MAGGAIN_5_6 = 0xC0 # +/- 5.6
+LSM303_MAGGAIN_8_1 = 0xE0 # +/- 8.1
+
+
+class LSM303(object):
+    """LSM303 accelerometer & magnetometer."""
+
+    def __init__(self, hires=True, accel_address=LSM303_ADDRESS_ACCEL,
+                 mag_address=LSM303_ADDRESS_MAG, i2c=None, **kwargs):
+        """Initialize the LSM303 accelerometer & magnetometer.  The hires
+        boolean indicates if high resolution (12-bit) mode vs. low resolution
+        (10-bit, faster and lower power) mode should be used.
+        """
+        # Setup I2C interface for accelerometer and magnetometer.
+        if i2c is None:
+            import Adafruit_GPIO.I2C as I2C
+            i2c = I2C
+        self._accel = i2c.get_i2c_device(accel_address, **kwargs)
+        self._mag = i2c.get_i2c_device(mag_address, **kwargs)
+        # Enable the accelerometer
+        self._accel.write8(LSM303_REGISTER_ACCEL_CTRL_REG1_A, 0x27)
+        # Select hi-res (12-bit) or low-res (10-bit) output mode.
+        # Low-res mode uses less power and sustains a higher update rate,
+        # output is padded to compatible 12-bit units.
+        if hires:
+            self._accel.write8(LSM303_REGISTER_ACCEL_CTRL_REG4_A, 0b00001000)
+        else:
+            self._accel.write8(LSM303_REGISTER_ACCEL_CTRL_REG4_A, 0)
+        # Enable the magnetometer
+        self._mag.write8(LSM303_REGISTER_MAG_MR_REG_M, 0x00)
+
+    def read(self):
+        """Read the accelerometer and magnetometer value.  A tuple of tuples will
+        be returned with:
+          ((accel X, accel Y, accel Z), (mag X, mag Y, mag Z))
+        """
+        # Read the accelerometer as signed 16-bit little endian values.
+        accel_raw = self._accel.readList(LSM303_REGISTER_ACCEL_OUT_X_L_A | 0x80, 6)
+        accel = struct.unpack('<hhh', accel_raw)
+        # Convert to 12-bit values by shifting unused bits.
+        accel = (accel[0] >> 4, accel[1] >> 4, accel[2] >> 4)
+        # Read the magnetometer.
+        mag_raw = self._mag.readList(LSM303_REGISTER_MAG_OUT_X_H_M, 6)
+        mag = struct.unpack('>hhh', mag_raw)
+        return (accel, mag)
+
+    def set_mag_gain(gain=LSM303_MAGGAIN_1_3):
+        """Set the magnetometer gain.  Gain should be one of the following
+        constants:
+         - LSM303_MAGGAIN_1_3 = +/- 1.3 (default)
+         - LSM303_MAGGAIN_1_9 = +/- 1.9
+         - LSM303_MAGGAIN_2_5 = +/- 2.5
+         - LSM303_MAGGAIN_4_0 = +/- 4.0
+         - LSM303_MAGGAIN_4_7 = +/- 4.7
+         - LSM303_MAGGAIN_5_6 = +/- 5.6
+         - LSM303_MAGGAIN_8_1 = +/- 8.1
+        """
+        self._mag.write8(LSM303_REGISTER_MAG_CRB_REG_M, gain)

Adafruit_LSM303/__init__.py

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+from .LSM303 import *

examples/simpletest.py

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+# Simple demo of of the LSM303 accelerometer & magnetometer library.
+# Will print the accelerometer & magnetometer X, Y, Z axis values every half
+# second.
+# Author: Tony DiCola
+# License: Public Domain
+import time
+
+# Import the LSM303 module.
+import Adafruit_LSM303
+
+
+# Create a LSM303 instance.
+lsm303 = Adafruit_LSM303.LSM303()
+
+# Alternatively you can specify the I2C bus with a bus parameter:
+#lsm303 = Adafruit_LSM303.LSM303(bus=2)
+
+print('Printing accelerometer & magnetometer X, Y, Z axis values, press Ctrl-C to quit...')
+while True:
+    # Read the X, Y, Z axis acceleration values and print them.
+    accel, mag = lsm303.read()
+    # Grab the X, Y, Z components from the reading and print them out.
+    accel_x, accel_y, accel_z = accel
+    mag_x, mag_y, mag_z = mag
+    print('Accel X={0}, Accel Y={1}, Accel Z={2}, Mag X={3}, Mag Y={4}, Mag Z={5}'.format(
+          accel_x, accel_y, accel_z, mag_x, mag_y, mag_z))
+    # Wait half a second and repeat.
+    time.sleep(0.5)