Meadow.Foundation.Sensors.Motion.Adxl345

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.

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

Class Adxl345

Driver for the ADXL345 triple axis accelerometer +/- 16g

Assembly: Adxl3xx.dll

View Source

Declaration

public class Adxl345 : ByteCommsSensorBase<Acceleration3D>, IObservable<IChangeResult<Acceleration3D>>, IDisposable, IAccelerometer, ISamplingSensor<Acceleration3D>, ISensor<Acceleration3D>, ISensor, ISamplingSensor, II2cPeripheral

Inheritance: System.Object -> Meadow.Foundation.ObservableBase<UNIT>

Implements:
System.IObservable<Meadow.IChangeResult<Meadow.Units.Acceleration3D>>, System.IDisposable, Meadow.Peripherals.Sensors.Motion.IAccelerometer, Meadow.Peripherals.Sensors.ISamplingSensor<Meadow.Units.Acceleration3D>, Meadow.Peripherals.Sensors.ISensor<Meadow.Units.Acceleration3D>, Meadow.Peripherals.Sensors.ISensor, Meadow.Peripherals.Sensors.ISamplingSensor, Meadow.Hardware.II2cPeripheral

Properties

DefaultI2cAddress

The default I2C address for the peripheral

View Source

Declaration

public byte DefaultI2cAddress { get; }

Acceleration3D

Current acceleration

View Source

Declaration

public Acceleration3D? Acceleration3D { get; }

OffsetX

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

View Source

Declaration

public sbyte OffsetX { get; set; }

OffsetY

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

View Source

Declaration

public sbyte OffsetY { get; set; }

OffsetZ

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

View Source

Declaration

public sbyte OffsetZ { get; set; }

Fields

MinimumPollingPeriod

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

View Source

Declaration

public const ushort MinimumPollingPeriod = 100

Methods

ReadSensor()

Read sensor

View Source

Declaration

protected override Task<Acceleration3D> ReadSensor()

Returns

System.Threading.Tasks.Task<Meadow.Units.Acceleration3D>: Current acceleration### SetPowerState(bool, bool, bool, bool, Frequencies) Set the PowerControl register (see pages 25 and 26 of the data sheet)

View Source

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)
Meadow.Foundation.Sensors.Motion.Adxl345.Frequencies	frequency	Frequency of measurements when the part is in sleep mode

SetDataFormat(bool, bool, bool, bool, GForceRanges)

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

View Source

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
Meadow.Foundation.Sensors.Motion.Adxl345.GForceRanges	range	Set the range of the sensor to 2g, 4g, 8g or 16g

SetDataRate(byte, bool)

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

View Source

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).

DisplayRegisters()

Dump the registers to the debug output stream.

View Source

Declaration

public void DisplayRegisters()

Implements

• System.IObservable<Meadow.IChangeResult<Meadow.Units.Acceleration3D>>
• System.IDisposable
• Meadow.Peripherals.Sensors.Motion.IAccelerometer
• Meadow.Peripherals.Sensors.ISamplingSensor<Meadow.Units.Acceleration3D>
• Meadow.Peripherals.Sensors.ISensor<Meadow.Units.Acceleration3D>
• Meadow.Peripherals.Sensors.ISensor
• Meadow.Peripherals.Sensors.ISamplingSensor
• Meadow.Hardware.II2cPeripheral