#----------------------------------------------------------------------------
# Copyright (c) FIRST 2008-2012. All Rights Reserved.
# Open Source Software - may be modified and shared by FRC teams. The code
# must be accompanied by the FIRST BSD license file in the root directory of
# the project.
#----------------------------------------------------------------------------
import hal
from .interfaces import Accelerometer
from .i2c import I2C
from .sensorbase import SensorBase
from .livewindow import LiveWindow
__all__ = ["ADXL345_I2C"]
[docs]class ADXL345_I2C(SensorBase):
"""
ADXL345 accelerometer device via i2c
"""
kAddress = 0x1D
kPowerCtlRegister = 0x2D
kDataFormatRegister = 0x31
kDataRegister = 0x32
kGsPerLSB = 0.00390625
kPowerCtl_Link = 0x20
kPowerCtl_AutoSleep = 0x10
kPowerCtl_Measure = 0x08
kPowerCtl_Sleep = 0x04
kDataFormat_SelfTest = 0x80
kDataFormat_SPI = 0x40
kDataFormat_IntInvert = 0x20
kDataFormat_FullRes = 0x08
kDataFormat_Justify = 0x04
Range = Accelerometer.Range
[docs] class Axes:
kX = 0x00
kY = 0x02
kZ = 0x04
def __init__(self, port, range):
"""Constructor.
:param port: The I2C port the accelerometer is attached to.
:param range: The range (+ or -) that the accelerometer will measure.
"""
self.i2c = I2C(port, self.kAddress)
# Turn on the measurements
self.i2c.write(self.kPowerCtlRegister, self.kPowerCtl_Measure)
self.setRange(range)
hal.HALReport(hal.HALUsageReporting.kResourceType_ADXL345,
hal.HALUsageReporting.kADXL345_I2C)
LiveWindow.addSensor("ADXL345_I2C", port, self)
# Accelerometer interface
[docs] def setRange(self, range):
"""Set the measuring range of the accelerometer.
:param range: The maximum acceleration, positive or negative, that
the accelerometer will measure.
:type range: :class:`ADXL345_I2C.Range`
"""
if range == self.Range.k2G:
value = 0
elif range == self.Range.k4G:
value = 1
elif range == self.Range.k8G:
value = 2
elif range == self.Range.k16G:
value = 3
else:
raise ValueError("Invalid range argument '%s'" % range)
# Specify the data format to read
self.i2c.write(self.kDataFormatRegister, self.kDataFormat_FullRes | value)
[docs] def getX(self):
"""Get the x axis acceleration
:returns: The acceleration along the x axis in g-forces
"""
return self.getAcceleration(self.Axes.kX)
[docs] def getY(self):
"""Get the y axis acceleration
:returns: The acceleration along the y axis in g-forces
"""
return self.getAcceleration(self.Axes.kY)
[docs] def getZ(self):
"""Get the z axis acceleration
:returns: The acceleration along the z axis in g-forces
"""
return self.getAcceleration(self.Axes.kZ)
[docs] def getAcceleration(self, axis):
"""Get the acceleration of one axis in Gs.
:param axis: The axis to read from.
:returns: An object containing the acceleration measured on each axis of the ADXL345 in Gs.
"""
data = self.i2c.read(self.kDataRegister + axis, 2)
# Sensor is little endian... swap bytes
rawAccel = (data[1] << 8) | data[0]
return rawAccel * self.kGsPerLSB
[docs] def getAccelerations(self):
"""Get the acceleration of all axes in Gs.
:returns: X,Y,Z tuple of acceleration measured on all axes of the
ADXL345 in Gs.
"""
data = self.i2c.read(self.kDataRegister, 6)
# Sensor is little endian... swap bytes
rawData = []
for i in range(3):
rawData.append((data[i*2+1] << 8) | data[i*2])
return (rawData[0] * self.kGsPerLSB,
rawData[1] * self.kGsPerLSB,
rawData[2] * self.kGsPerLSB)
# Live Window code, only does anything if live window is activated.
def getSmartDashboardType(self):
return "3AxisAccelerometer"
def initTable(self, subtable):
self.table = subtable
self.updateTable()
def getTable(self):
return self.table
def updateTable(self):
if self.table is not None:
self.table.putNumber("X", self.getX())
self.table.putNumber("Y", self.getY())
self.table.putNumber("Z", self.getZ())
def startLiveWindowMode(self):
"""
ADXL345_I2C doesn't have to do anything special when entering the LiveWindow.
"""
pass
def stopLiveWindowMode(self):
"""
ADXL345_I2C doesn't have to do anything special when exiting the LiveWindow.
"""
pass