Ultrabook Development Using Sensors - Intel AppLab Berlin

Application Development using
Sensors
Intel® Corporation

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Copyright© 2012, Intel Corporation. All rights reserved. *Other
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brands and All dates, plans and of their respective owners 2

Agenda
• Overview of available sensors
• Using sensors in a Windows 8* application
- In C++ desktop applications, using COM interface
- In C++ or C#/.NET Windows 8* store and desktop
applications, using WinRT APIs
• Considerations on Efficiency

Copyright(C) 2012 Intel Corporation. All rights reserved. *Other brands and names are properties of their respective owners.
3

Who am I ?

Xavier Hallade (@ph0b)
Technical Marketing Engineer at Intel
4

Sensors
OVERVIEW OF AVAILABLE SENSORS

Copyright(C) 2012 Intel Corporation. All rights reserved.
*Other brands and names are properties of their respective owners. 5

Available Sensors

Compass Accelerometer Gyroscope GPS Ambient Light NFC

+ with Sensor Fusion: Inclinometer, Orientation, SimpleOrientation

• Sensor Fusion : virtual sensors created by combining data
from compass, accelerometer and gyroscope
• Ambient Light, GPS, 3D Motion and orientation sensors are
all mandatory on Windows 8* Tablets and Convertibles
• Applications can subscribe to sensor events, set callbacks or
directly poll their current state.

Orientation and Motion detection
• Gyrometer returns yaw, pitch and roll velocities
• Accelerometer returns acceleration along x, y and z,
and optionally a Shake event
• Simple Orientation : returns device orientation into
one of four quadrants, face-up, or face-down
• Orientation Sensor and inclinometer both returns
the complete device orientation
– Inclinometer returns yaw, pitch, and roll angles
– Orientation Sensor returns a quaternion as well as a 3x3
orientation matrix

Orientation and Motion detection
same convention as on Android
and in the HTML5 specification

0.0° ≤ Yaw < 360.0°
-180.0° ≤ Pitch < 180.0°
-90.0° ≤ Roll < 90.0°

Ambient Light
• Can be used to adapt application interface
depending on light conditions : contrast,
font size
• Screen brightness control should be handled
by the operating system.
Lighting condition Illuminance (lux)
Pitch black 1
Very dark 10
Dark indoors 50
Dim indoors 100
Normal indoors 300
Bright indoors 1,000
Dim outdoors 5,000
Cloudy outdoors 30,000
Direct sunlight 100,000

Location
Returns latitude, longitude:
- using Wi-Fi if available
- using IP Address otherwise
- using GPS if available and desired accuracy is set
on High
- then it can also return Altitude, Speed and Heading

Depending on user’s choice, its use can be denied.
A Windows 8* store app has to declare the
“location” capability in its manifest.

Near Field Communication

• Short range (<4cm)
• Contactless
• Used between active and/or passive devices
– Active: Smartphone, Tablet, Ultrabook™…
– Passive: Tags, Smart cards…
• Small amount of data, low data transfer rate
• Easy to use, feels instantaneous (<1/10s)
-> Great user experience !

Near Field Communication
• Pairing
– with Bluetooth* peripherals, at the OS level
– with another running application, by establishing
a BT or Wi-Fi direct socket, at the application level
• Short data read/write on NFC tags
• Short data exchange with active devices
– Sharing URIs, contacts, positions
– Secure transactions

NFC messages
Protocol Pub. Sub. Message contents
Windows X X binary data.
WindowsUri X X UTF-16LE encoded string that is a URI.
use PublishUriMessage
WindowsMime X X message data of a specific mime type.
For example, "WindowsMime.image/jpeg".
You can subscribe to "WindowsMime" message
without specifying the mime type. If so, the first 256
bytes received is the ASCII mime type string.
Windows:WriteTag X Windows message to be written to a static tag.
WindowsUri:WriteTag X WindowsUri message to be written to a static tag.
WindowsMime:Write X WindowsMime message to be written to a static tag.
Tag Example, “WindowsMime:WriteTag.image/jpeg”
LaunchApp:WriteTag X Write a tag that can be used to launch a specific app.
more information on msdn.
WriteableTag X if a writeable tag is brought in to proximity, a
proximity message is received that contains an
int32 indicating the maximum writeable size.

NFC messages
Windows messages are fully compatible with NDEF messages,
but you can also directly manipulate them :
Protocol Pub. Sub. Message contents
NDEF X X properly formatted NDEF records.
NDEF:ext X application defined NDEF records (TNF field value of 0x04).
NDEF:MIME X properly formatted NDEF mime message (TNF field value
of 0x02). For example, "NDEF:MIME.image/jpeg".
NDEF:URI X properly formatted NDEF message of a type defined by a
URI namespace (TNF field value of 0x03). For example,
"NDEF:URI.http://contoso.com/sometype".
NDEF:wkt X properly formatted NDEF message of a type defined by the
NFC forum (TNF field value of 0x01).An example of this
type is "NDEF:wkt.U" for the well known type of URI.
NDEF:WriteTag X message data that should be written to an NFC forum
standard static tag.
NDEF:Unknown X untyped NDEF message (TNF field value of 0x05).

Sensors
LET’S DIVE INTO SOME CODE !


Sensors and Location Platform
using COM interface
FROM C++


Sensors and Location Platform
• Same interface as on Windows 7
– Sensor fusion available through new GUIDs
• Sensor manager controls sensors
– Use sensor manager to get to sensors
– Notifies when a sensor connects
• Sensors report data, changes in state and disconnection
• Access both via COM interfaces
– Use API to communicate to sensors
– Sensor events handled using callbacks
– API reference at msdn.microsoft.com/en-
us/library/windows/desktop/dd318953%28v=vs.85%29.aspx

17

COM: Connect to sensor manager
// Create the sensor manager
• Access to sensors is through the
sensor manager ISensorManager pSensorManager;

hr = CoCreateInstance(CLSID_SensorManager,
• Group policy settings may deny NULL, CLSCTX_INPROC_SERVER,
IID_PPV_ARGS(&pSensorManager));
access to the system sensors
if(hr == HRESULT_FROM_WIN32
(ERROR_ACCESS_DISABLED_BY_POLICY))
{
// Unable to retrieve sensor manager due
// to group policy settings.
// Alert the user.
}

(Source: Microsoft)

18

COM: Retrieve a sensor object
// Get the sensor collection
• Request sensors by category, type hr = pSensorManager->GetSensorsByCategory(
SENSOR_CATEGORY_ALL,
or ID &pSensorColl);
if(SUCCEEDED(hr))
{
ULONG ulCount = 0;
// Verify that the collection contains at
// least one sensor
hr = pSensorColl->GetCount(&ulCount);
if(SUCCEEDED(hr))
{
if(ulCount < 1)
{
• Request permission to use the wprintf_s(L"nNo sensors of the
requested category.n");
hr = E_UNEXPECTED;
sensor(s) } else
{
• Windows 8 will open a dialog // Request permissions for all sensors
// in the collection
box to ask the user hr = pSensorManager->
RequestPermissions(0, pSensorColl,
• Granting permission triggers }
FALSE);
…
the OnStateChanged event
(Source: Microsoft)

19

COM: Sensor event callback
class CMyEvents : public ISensorEvents
• Receive event notifications by
{
implementing required COM public:
interfaces
STDMETHODIMP QueryInterface(…) {…}
STDMETHODIMP_(ULONG) AddRef() {…}
• Sensor events require STDMETHODIMP_(ULONG) Release() {…}

ISensorEvents
// ISensorEvents methods. //
STDMETHODIMP OnEvent(…) {…}
• Sensor Manager events require STDMETHODIMP OnDataUpdated(…) {…}
STDMETHODIMP OnLeave(…) {…}
ISensorManagerEvents STDMETHODIMP OnStateChanged(…) {…}
…

(Source: Microsoft)

20

COM: Start receiving events
// Create an instance of the event
• To start receiving events provide // class
the sensor with a pointer to your pEventClass = new(std::nothrow)
CMyEvents();
callback
if(SUCCEEDED(hr))
• To stop receiving events call {
// Retrieve the pointer to the
SetEventSink with a parameter of // callback interface
NULL hr = pEventClass->QueryInterface(
IID_PPV_ARGS(&pMyEvents));
}
if(SUCCEEDED(hr))
{
// Start receiving events
hr = pSensor->
SetEventSink(pMyEvents);
}

(Source: Microsoft)

21

Ambient Light Sensor
DEMO

22

Using WinRT Sensors and
Location API
FROM C# AND C++/CX


WinRT API
• Windows.Sensors.
• Accelerometer
• Gyrometer
• Inclinometer
• OrientationSensor
• SimpleOrientationSensor
• Compass
• LightSensor
• Windows.Networking.Proximity.ProximityDevice (NFC)
• Windows.Device.Geolocation (GPS)

Copyright© 2012, Intel Corporation. All rights reserved. *Other brands and names are the property of their respective owners

Using the WinRT API
WinRT Sensors and Location APIs are available to
Windows 8* Desktop applications

You need to use WinRT Windows MetaData files :
• Platform.winmd:
C:Program Files (x86)Microsoft SDKsWindowsv8.0ExtensionSDKsMicrosoft.VCLi
bs11.0ReferencesCommonConfigurationneutral

• Windows.winmd:
C:Program Files (x86)Windows Kits8.0ReferencesCommonConfigurationNeutral

How ?

WinRT From Desktop (C#)
Unload your C# Project
Manually edit the .csproj file to add :
<PropertyGroup>
<TargetPlatformVersion>8.0</TargetPlatformVersion>
</PropertyGroup>
Reload the project
Add Windows.winmd and Platform.winmd as references
from their respective locations


WinRT From Desktop (C++)
In your project properties, in C/C++->General:
• Set “Consume Windows Runtime Extension” on Yes
(/ZW)
• Add Windows.winmd and Platform.winmd paths to
“Additional #using Directories”
In your source code, add :
#using <Windows.winmd>
#using <Platform.winmd>


WinRT Sensor API
No need for a sensor manager:

1 – Retrieve the default sensor/device using GetDefault()
2 – Set the ReportInterval
3 – Add a delegate to ReadingChanged event


WinRT Sensor API
_accelero = Accelerometer.GetDefault();
if (_accelero != null)
{
_accelero.ReportInterval = 50 <= _accelero.MinimumReportInterval ?
_accelerometer.MinimumReportInterval : 50;
//Register for reading changed events
_accelero.ReadingChanged += (Accelerometer s, AccelerometerReadingChangedEventArgs
args) =>
{
//use e.Data.AccelerationX/Y/Z
};
}
C#

Accelerometer ^accelero = Accelerometer::GetDefault();
if(accelero!=nullptr)
{
accelero->ReportInterval = 50 <= accelero->MinimumReportInterval ? accelero-
>MinimumReportInterval : 50;
accelero->ReadingChanged += ref new TypedEventHandler<Accelerometer^,
AccelerometerReadingChangedEventArgs^>(
[](Object^ sender, AccelerometerReadingChangedEventArgs^ e)
{
//read e->Data->AccelerationX/Y/Z
});
}
C++

C#/WPF Accelerometer Demo
• Ellipse (ball) drawn on a canvas
• Accelerometer data is used to update X/Y/Z
display and location of ball
• Data is read using
accelerometer events in
conjunction with a
timer to move the ball

30

C#/WPF NFC DEMO
• Subscribe to incoming WindowsURI messages
• Publish a WindowsURI message to any active
device
• Write that
message to any
writable tag

31

USING SENSORS EFFICIENTLY


General Considerations
• The effects of applications on power use
• Both idle workloads and active workloads
• The rules of power management
– Computational efficiency
– Maximize idle
– Data efficiency
– Power-aware behavior
• Align, coalesce or batch activity whenever
possible

33

Regarding Sensors
• Do not set a small ReportInterval if your application doesn’t
need it
• Avoid periodic registry or disk accesses in order to let the
hard disk spin down
• Avoid status polling, statistics & background bookkeeping
• Avoid using sensors when application is not active
• Consider using accelerometer or gyroscope alone if full
orientation is not needed.

Sensors objects in Sensors API: At least one client connected
Hardware: Accelerometer Gyroscope Inclinometer Compass Device Orientation
Accelerometer On Off On On On
Gyro Off On On On On
Magnetometer Off Off On On On

34

Advanced : Context/power-aware
behavior
• Handling sleep transitions seamlessly
– Saving an restoring state
– Stopping ongoing activity prior to sleeping
– Closing open resources & disconnecting communications
• Respond/adapt to system power events
– Switching from AC to battery; low battery status
• Scale behavior based on power state
• Context awareness toolkits
– software.intel.com/en-us/mobility
– softwarecommunity.intel.com/articles/eng/1070.htm
– softwarecommunity.intel.com/articles/eng/1026.htm

35

Intel Software Development Products
Intel Power Tools
• Intel® Power Checker
– Reveals how much power your application is using
– software.intel.com/partner/app/software-
assessment/?cid=sw:ubpower004
• Energy-Efficient Software Checklist
– software.intel.com/en-us/articles/energy-
efficient-software-checklist/

36

References
• Intel® Software Network
– software.intel.com
• COM Sensor API
– msdn.microsoft.com/en-us/library/windows/desktop/dd318953(v=vs.85).aspx
• COM Location API
– msdn.microsoft.com/en-us/library/dd464636(v=VS.85).aspx
• WinRT Sensors API
– msdn.microsoft.com/en-us/library/windows/apps/br206408.aspx
• WinRT Geolocation API
– msdn.microsoft.com/en-us/library/windows/apps/windows.devices.geolocation.aspx
• WinRT ProximityAPI
– msdn.microsoft.com/en-us/library/windows/apps/windows.networking.proximity.aspx
• Detecting Ultrabook Sensors
– software.intel.com/en-us/blogs/2012/07/26/detecting-ultrabook-sensors
• Ultrabook and Tablet Windows 8* Sensors Development Guide
– software.intel.com/en-us/articles/ultrabook-and-tablet-windows-8-sensors-development-guide/
• Intel® Energy Efficient Software Guidelines
– software.intel.com/partner/assets/pdf/misc/Energy_Efficient_Software_Guidelines_v3_4_10_11.pdf

37

Summary
– sensors are a natural way to interact with end
users
– Desktop apps can utilize them as well as Windows
8* Store Apps
– Utilize efficient designs and coding practices to
save battery life

38

Q&A

39

END
• START OF NEXT SESSION IN 15 MINS.
• Ultrabook Developer Resources

40

Ultrabook Development Using Sensors - Intel AppLab Berlin

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