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‎Adafruit_ADXL345/ADXL345.py

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import struct
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# Minimal constants carried over from Arduino library
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ADXL345_ADDRESS = 0x53
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ADXL345_REG_DEVID = 0x00 # Device ID
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ADXL345_REG_DATAX0 = 0x32 # X-axis data 0 (6 bytes for X/Y/Z)
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ADXL345_REG_POWER_CTL = 0x2D # Power-saving features control
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ADXL345_REG_DATA_FORMAT = 0x31
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ADXL345_REG_BW_RATE = 0x2C
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ADXL345_DATARATE_0_10_HZ = 0x00
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ADXL345_DATARATE_0_20_HZ = 0x01
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ADXL345_DATARATE_0_39_HZ = 0x02
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ADXL345_DATARATE_0_78_HZ = 0x03
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ADXL345_DATARATE_1_56_HZ = 0x04
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ADXL345_DATARATE_3_13_HZ = 0x05
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ADXL345_DATARATE_6_25HZ = 0x06
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ADXL345_DATARATE_12_5_HZ = 0x07
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ADXL345_DATARATE_25_HZ = 0x08
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ADXL345_DATARATE_50_HZ = 0x09
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ADXL345_DATARATE_100_HZ = 0x0A # (default)
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ADXL345_DATARATE_200_HZ = 0x0B
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ADXL345_DATARATE_400_HZ = 0x0C
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ADXL345_DATARATE_800_HZ = 0x0D
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ADXL345_DATARATE_1600_HZ = 0x0E
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ADXL345_DATARATE_3200_HZ = 0x0F
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ADXL345_RANGE_2_G = 0x00 # +/- 2g (default)
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ADXL345_RANGE_4_G = 0x01 # +/- 4g
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ADXL345_RANGE_8_G = 0x02 # +/- 8g
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ADXL345_RANGE_16_G = 0x03 # +/- 16g
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class ADXL345(object):
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"""ADXL345 triple-axis accelerometer."""
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def __init__(self, address=ADXL345_ADDRESS, i2c=None, **kwargs):
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"""Initialize the ADXL345 accelerometer using its I2C interface.
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"""
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# Setup I2C interface for the device.
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if i2c is None:
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import Adafruit_GPIO.I2C as I2C
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i2c = I2C
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self._device = i2c.get_i2c_device(address, **kwargs)
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# Check that the acclerometer is connected, then enable it.
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if self._device.readU8(ADXL345_REG_DEVID) == 0xE5:
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self._device.write8(ADXL345_REG_POWER_CTL, 0x08)
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else:
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raise RuntimeError('Failed to find the expected device ID register value, check your wiring.')
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def set_range(self, value):
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"""Set the range of the accelerometer to the provided value. Range value
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should be one of these constants:
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- ADXL345_RANGE_2_G = +/-2G
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- ADXL345_RANGE_4_G = +/-4G
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- ADXL345_RANGE_8_G = +/-8G
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- ADXL345_RANGE_16_G = +/-16G
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"""
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# Read the data format register to preserve bits. Update the data
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# rate, make sure that the FULL-RES bit is enabled for range scaling
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format_reg = self._device.readU8(ADXL345_REG_DATA_FORMAT) & ~0x0F
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format_reg |= value
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format_reg |= 0x08 # FULL-RES bit enabled
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# Write the updated format register.
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self._device.write8(ADXL345_REG_DATA_FORMAT, format_reg)
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def get_range(self):
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"""Retrieve the current range of the accelerometer. See set_range for
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the possible range constant values that will be returned.
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"""
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return self._device.readU8(ADXL345_REG_DATA_FORMAT) & 0x03
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def set_data_rate(self, rate):
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"""Set the data rate of the aceelerometer. Rate should be one of the
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following constants:
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- ADXL345_DATARATE_0_10_HZ = 0.1 hz
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- ADXL345_DATARATE_0_20_HZ = 0.2 hz
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- ADXL345_DATARATE_0_39_HZ = 0.39 hz
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- ADXL345_DATARATE_0_78_HZ = 0.78 hz
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- ADXL345_DATARATE_1_56_HZ = 1.56 hz
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- ADXL345_DATARATE_3_13_HZ = 3.13 hz
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- ADXL345_DATARATE_6_25HZ = 6.25 hz
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- ADXL345_DATARATE_12_5_HZ = 12.5 hz
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- ADXL345_DATARATE_25_HZ = 25 hz
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- ADXL345_DATARATE_50_HZ = 50 hz
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- ADXL345_DATARATE_100_HZ = 100 hz
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- ADXL345_DATARATE_200_HZ = 200 hz
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- ADXL345_DATARATE_400_HZ = 400 hz
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- ADXL345_DATARATE_800_HZ = 800 hz
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- ADXL345_DATARATE_1600_HZ = 1600 hz
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- ADXL345_DATARATE_3200_HZ = 3200 hz
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"""
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# Note: The LOW_POWER bits are currently ignored,
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# we always keep the device in 'normal' mode
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self._device.write8(ADXL345_REG_BW_RATE, rate & 0x0F)
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def get_data_rate(self):
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"""Retrieve the current data rate. See set_data_rate for the possible
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data rate constant values that will be returned.
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"""
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return self._device.readU8(ADXL345_REG_BW_RATE) & 0x0F
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def read(self):
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"""Read the current value of the accelerometer and return it as a tuple
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of signed 16-bit X, Y, Z axis values.
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"""
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raw = self._device.readList(ADXL345_REG_DATAX0, 6)
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return struct.unpack('<hhh', raw)

‎Adafruit_ADXL345/__init__.py

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from .ADXL345 import *

‎examples/simpletest.py

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# Simple demo of of the ADXL345 accelerometer library. Will print the X, Y, Z
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# axis acceleration values every half second.
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# Author: Tony DiCola
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# License: Public Domain
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import time
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# Import the ADXL345 module.
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import Adafruit_ADXL345
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# Create an ADXL345 instance.
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accel = Adafruit_ADXL345.ADXL345()
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# You can optionally change the range to one of:
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# - ADXL345_RANGE_2_G = +/-2G (default)
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# - ADXL345_RANGE_4_G = +/-4G
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# - ADXL345_RANGE_8_G = +/-8G
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# - ADXL345_RANGE_16_G = +/-16G
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# For example to set to +/- 16G:
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#accel.set_range(Adafruit_ADXL345.ADXL345_RANGE_16_G)
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# Or change the data rate to one of:
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# - ADXL345_DATARATE_0_10_HZ = 0.1 hz
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# - ADXL345_DATARATE_0_20_HZ = 0.2 hz
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# - ADXL345_DATARATE_0_39_HZ = 0.39 hz
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# - ADXL345_DATARATE_0_78_HZ = 0.78 hz
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# - ADXL345_DATARATE_1_56_HZ = 1.56 hz
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# - ADXL345_DATARATE_3_13_HZ = 3.13 hz
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# - ADXL345_DATARATE_6_25HZ = 6.25 hz
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# - ADXL345_DATARATE_12_5_HZ = 12.5 hz
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# - ADXL345_DATARATE_25_HZ = 25 hz
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# - ADXL345_DATARATE_50_HZ = 50 hz
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# - ADXL345_DATARATE_100_HZ = 100 hz (default)
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# - ADXL345_DATARATE_200_HZ = 200 hz
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# - ADXL345_DATARATE_400_HZ = 400 hz
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# - ADXL345_DATARATE_800_HZ = 800 hz
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# - ADXL345_DATARATE_1600_HZ = 1600 hz
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# - ADXL345_DATARATE_3200_HZ = 3200 hz
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# For example to set to 6.25 hz:
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#accel.set_data_rate(Adafruit_ADXL345.ADXL345_DATARATE_6_25HZ)
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print('Printing X, Y, Z axis values, press Ctrl-C to quit...')
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while True:
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# Read the X, Y, Z axis acceleration values and print them.
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x, y, z = accel.read()
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print('X={0}, Y={1}, Z={2}'.format(x, y, z))
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# Wait half a second and repeat.
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time.sleep(0.5)

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