Jim Travis's Blog

Use your Wii-mote as a sensor with the Windows 7 Sensor Platform

jimtravis — Thu, 11 Feb 2010 22:14:00 GMT

A cool Wii-mote driver project on The Code Project:

http://www.codeproject.com/KB/system/wiisensor.aspx

Windows Sensors on Channel 9 and Coding4Fun Arduino sensors

jimtravis — Sat, 30 Jan 2010 03:36:00 GMT

Channel 9 discusses generic sensor driver from O'Reilly:

http://channel9.msdn.com/shows/This+Week+On+Channel+9/TWC9-Hack-Powerwheels-APIs-for-Wikipedia-Smooth-Streaming-Arduinos-and-more/

Coding4Fun topic about Arduino sensors:

http://blogs.msdn.com/coding4fun/archive/2010/01/15/9949045.aspx

Facebook group for Windows Developers

jimtravis — Fri, 22 Jan 2010 01:21:00 GMT

Gus Class has created a Facebook group called "Windows Developers." If you use Facebook, come join us.

Using Windows 7 to Monitor a Motion Sensor

jimtravis — Sun, 06 Dec 2009 20:15:00 GMT

Donn Morse has posted sample code and a white paper here:

http://code.msdn.microsoft.com/motionsensor

The whitepaper describes how you can build a simple motion sensor, a Sensor device driver, and a Sensor application that you can use to observe real-time sensor data in Windows 7.

The sample firmware can be used to program a Parallax BS2 microcontroller.

Learning Pathways for Sensors and Location

jimtravis — Tue, 27 Oct 2009 05:41:00 GMT

We've published a new Windows Developer Center on MSDN. Part of the update includes a nice page for learning about Windows 7 sensors and location. Here's the link: http://msdn.microsoft.com/en-us/windows/ee658252.aspx

Enjoy!

u-blox Releases Windows 7 Driver

jimtravis — Wed, 16 Sep 2009 01:30:00 GMT

Press release here: http://www.u-blox.com/en/press-and-events/press-release-archive/845.html

If you're looking for GPS hardware to use for developing your Windows 7 location-aware apps, u-blox has a solution available now.

Driver here: http://www.u-blox.com/en/usb-drivers/windows-7-driver.html

Sensor API interop in Windows API Code Pack

jimtravis — Sat, 01 Aug 2009 02:31:00 GMT

Here's a source code release for .NET interop with Win32 features, including the Sensor API:

http://code.msdn.microsoft.com/WindowsAPICodePack

The Windows® API Code Pack for Microsoft® .NET Framework provides a source code library that can be used to access some new Windows 7 features (and some existing features of older versions of Windows operating system) from managed code. These Windows features are not available to developers today in the .NET Framework.

Sensor Constants and VECTOR Types

jimtravis — Tue, 14 Jul 2009 01:04:00 GMT

In the Windows 7 Sensor platform, some properties and data fields contain arrays of information. For example, the SENSOR_PROPERTY_LIGHT_RESPONSE_CURVE property contains an array of 4-byte unsigned integers. However, when you receive such arrays through the Sensor API, they will always represented as type VT_VECTOR|UI1, an array of single-byte characters, regardless of the actual type of the data in the array. This requirement arises because the platform uses the WPD serializer when moving data from the sensor class extension to the API layer. The WPD serializer can serialize arrays of data only if the individual data type is UI1.

From the driver perspective, this means that PROPVARIANT for these array types should be created by using InitPropVariantFromBuffer. This function creates the PROPVARIANT as type VT_VECTOR|UI1. Here's some example code that creates a light response curve:

UINT responseCurve[10] = {0}; // Array to contain the response curve data.

// ****************************************************************************************

// The response curve consists of an array of integer pairs.

// The first integer contains the percentage brightness offset to be applied to the display.

// The second integer contains the corresponding ambient light value (in LUX).

// ****************************************************************************************

// (0, 10)

responseCurve[0] = 0; responseCurve[1] = 10;

// (10, 40)

responseCurve[2] = 10; responseCurve[3] = 40;

// (40, 80)

responseCurve[4] = 40; responseCurve[5] = 80;

// (68, 100)

responseCurve[6] = 68; responseCurve[7] = 100;

// (90, 150)

responseCurve[8] = 90; responseCurve[9] = 150;

// Create the buffer.

PROPVARIANT pvCurve = {0};

InitPropVariantFromBuffer(responseCurve, 10 * sizeof (UINT), &pvCurve);

// Add the values to the IPortableDeviceValues object.

hr = m_pSensorProperties->SetValue(SENSOR_PROPERTY_LIGHT_RESPONSE_CURVE, &pvCurve);

PropVariantClear(&pvCurve);

From the API perspective, you must be careful to cast arrays to the correct data type for the property or data field. Here's an example of how to "unpack" the light response curve data on the API side:

PROPVARIANT pvCurve;
PropVariantInit(&pvCurve);

// Retrieve the property value.
hr = pSensor->GetProperty(SENSOR_PROPERTY_LIGHT_RESPONSE_CURVE, &pvCurve);
if (SUCCEEDED(hr))
{
    if ((VT_UI1|VT_VECTOR) == V_VT(pvCurve)) // Note actual type of UI1
    {
        // Cast the array to UINT, a 4-byte unsigned integer.

        // Item count for the array.
        UINT cElement = pvCurve.caub.cElems/sizeof(UINT);
        // Array pointer.
        UINT* pElement = (UINT*)(pvCurve.caub.pElems);

// Use the array.
}
}

// Remember to free the PROPVARIANT when done.
PropVariantClear(&pvCurve);

Earlier documentation for the Sensor API and WDK (or the header, sensors.h) did not call out this re-typing requirement. We've been updating the docs, but the header comments will continue to show the actual data type, without mention of the serialization issue.

New page on Freescale's Web site for the Windows 7 Sensor Development Kit

jimtravis — Wed, 10 Jun 2009 02:04:00 GMT

http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=JMBADGE2008-B

Location Sensors Question from a Reader

jimtravis — Thu, 04 Jun 2009 08:29:00 GMT

A reader asks:

I've searched for information on Internet how to say to Windows 7 that external Bluetooth GPS should be used as the location sensor, but actually I have not found any answers, just the similar questions in forums. Probably it would be a good post in your blog which will explain what is possible and what not. I suspect there should be some driver support for translating information from Bluetooth COM ports to location, but it should be some class driver that is part of Sensor & Location API. I am using Nokia LD-3W BT GPS. It has category Other and from services there is only Serial Port. GPS function works just fine with legacy applications that use COM port directly, but I would like to know how Win7 can utilize this device as Location sensor.

The Sensor and Location platform in Windows 7 does not provide a class driver for location sensors. In this particular instance, Nokia would have to write an updated native driver for the GPS. Alternatively, you could write a COM port-based sensor driver, but this is not a trivial exercise.