Remarks

Adxl345
Status
Source code	GitHub
Datasheet(s)	GitHub
NuGet package

The ADXL345 is a small, low power, triple axis acceleration sensor capable of measuring up to +/-16g with a resolution of 13-bits.

The ADXL345 is controlled via I2C.

The ADXL345 can operating in interrupt and polling mode. Polling applications are responsible for determining when a sensor is read. Interrupt applications will be notified when the sensor reading changes by + / - a threshold value.

Purchasing

The ADXL345 is available on a small breakout board:

• Sparkfun ADXL345 Breakout Board

Code Example

Adxl345 sensor;

public MeadowApp()
{
    Console.WriteLine("Initializing");

    sensor = new Adxl345(Device.CreateI2cBus());
    sensor.SetPowerState(false, false, true, false, Adxl345.Frequencies.TwoHz);

    // classical .NET events can also be used:
    sensor.Updated += (sender, result) =>
    {
        Console.WriteLine($"Accel: [X:{result.New.X.MetersPerSecondSquared:N2}," +
            $"Y:{result.New.Y.MetersPerSecondSquared:N2}," +
            $"Z:{result.New.Z.MetersPerSecondSquared:N2} (m/s^2)]");
    };

    //==== one-off read
    ReadConditions().Wait();

    // start updating
    sensor.StartUpdating(TimeSpan.FromMilliseconds(500));
}

protected async Task ReadConditions()
{
    var result = await sensor.Read();
    Console.WriteLine("Initial Readings:");
    Console.WriteLine($"Accel: [X:{result.X.MetersPerSecondSquared:N2}," +
        $"Y:{result.Y.MetersPerSecondSquared:N2}," +
        $"Z:{result.Z.MetersPerSecondSquared:N2} (m/s^2)]");
}

Sample project(s) available on GitHub

Wiring Example

Characteristic	Locus
Inheritance	System.Object > Adxl345
Implements	IAccelerometer
Namespace	Meadow.Foundation.Sensors.Motion
Assembly	Adxl3xx.dll

Syntax

public class Adxl345 : ByteCommsSensorBase<Acceleration3D>, IAccelerometer

Constructors

Adxl345(II2cBus, Adxl345.Addresses)

Create a new instance of the ADXL345 communicating over the I2C interface.

Declaration

public Adxl345(II2cBus i2cBus, Adxl345.Addresses address = default(Adxl345.Addresses))

Parameters

Type	Name	Description
II2cBus	i2cBus	I2C bus
Adxl345.Addresses	address	Address of the I2C sensor

Adxl345(II2cBus, Byte)

Create a new instance of the ADXL345 communicating over the I2C interface.

Declaration

public Adxl345(II2cBus i2cBus, byte address)

Parameters

Type	Name	Description
II2cBus	i2cBus	I2C bus
System.Byte	address	Address of the I2C sensor

Fields

MinimumPollingPeriod

Minimum value that can be used for the update interval when the sensor is being configured to generate interrupts.

Declaration

public const ushort MinimumPollingPeriod = null

Field Value

Type	Description
System.UInt16

Properties

Acceleration3D

Current acceleration

Declaration

public Acceleration3D? Acceleration3D { get; }

Property Value

Type	Description
System.Nullable<Acceleration3D>

OffsetX

Values stored in this register are automatically added to the X reading.

Declaration

public sbyte OffsetX { get; set; }

Property Value

Type	Description
System.SByte

Remarks

Scale factor is 15.6 mg/LSB so 0x7f represents an offset of 2g.

OffsetY

Values stored in this register are automatically added to the Y reading.

Declaration

public sbyte OffsetY { get; set; }

Property Value

Type	Description
System.SByte

Remarks

Scale factor is 15.6 mg/LSB so 0x7f represents an offset of 2g.

OffsetZ

Values stored in this register are automatically added to the Z reading.

Declaration

public sbyte OffsetZ { get; set; }

Property Value

Type	Description
System.SByte

Remarks

Scale factor is 15.6 mg/LSB so 0x7f represents an offset of 2g.

Methods

DisplayRegisters()

Dump the registers to the debug output stream.

Declaration

public void DisplayRegisters()

RaiseEventsAndNotify(IChangeResult<Acceleration3D>)

Raise changed event for subscribers

Declaration

protected override void RaiseEventsAndNotify(IChangeResult<Acceleration3D> changeResult)

Parameters

Type	Name	Description
IChangeResult<Acceleration3D>	changeResult

ReadSensor()

Read sensor

Declaration

protected override Task<Acceleration3D> ReadSensor()

Returns

Type	Description
Task<Acceleration3D>	Current acceleration

SetDataFormat(Boolean, Boolean, Boolean, Boolean, Adxl345.GForceRanges)

Configure the data format (see pages 26 and 27 of the data sheet).

Declaration

public void SetDataFormat(bool selfTest, bool spiMode, bool fullResolution, bool justification, Adxl345.GForceRanges range)

Parameters

Type	Name	Description
System.Boolean	selfTest	Put the device into self test mode when true.
System.Boolean	spiMode	Use 3-wire SPI (true) or 4-wire SPI (false).
System.Boolean	fullResolution	Set to full resolution (true) or 10-bit mode using the range determined by the range parameter (false).
System.Boolean	justification	Left-justified when true, right justified with sign extension when false.
Adxl345.GForceRanges	range	Set the range of the sensor to 2g, 4g, 8g or 16g

Remarks

The range of the sensor is determined by the following table: 0: +/- 2g 1: +/- 4g 2: +/- 8g 3: +/ 16g

SetDataRate(Byte, Boolean)

Set the data rate and low power mode for the sensor.

Declaration

public void SetDataRate(byte dataRate, bool lowPower)

Parameters

Type	Name	Description
System.Byte	dataRate	Data rate for the sensor.
System.Boolean	lowPower	Setting this to true will enter low power mode (note measurement will encounter more noise in this mode).

SetPowerState(Boolean, Boolean, Boolean, Boolean, Adxl345.Frequencies)

Set the PowerControl register (see pages 25 and 26 of the data sheet)

Declaration

public void SetPowerState(bool linkActivityAndInactivity, bool autoSleep, bool measuring, bool sleep, Adxl345.Frequencies frequency)

Parameters

Type	Name	Description
System.Boolean	linkActivityAndInactivity	Link the activity and inactivity events.
System.Boolean	autoSleep	Enable / disable auto sleep when the activity and inactivity are linked.
System.Boolean	measuring	Enable or disable measurements (turn on or off).
System.Boolean	sleep	Put the part to sleep (true) or run in normal more (false).
Adxl345.Frequencies	frequency	Frequency of measurements when the part is in sleep mode.

Events

Acceleration3DUpdated

Event raised when acceleration changes

Declaration

public event EventHandler<IChangeResult<Acceleration3D>> Acceleration3DUpdated

Event Type

Type	Description
EventHandler<IChangeResult<Acceleration3D>>