Where the .NET Micro Framework Fits

Now that we have looked at the benefits of managed code, let’s examine where the .NET Micro Framework fits in the range of Microsoft’s offerings (see Figure 1-6). Windows XP, Windows XP Embedded, and Windows Vista support the full .NET Framework, while Windows CE supports the .NET Compact Framework. There might be an overlap among the offerings, so two systems might fit well and be good choices for a given application.

The .NET Micro Framework is the smallest .NET platform to date and provides only a subset of the full .NET Framework and .NET Compact Framework. While Windows CE configurations supporting managed code with the.NET Compact Framework require at least 12MB of RAM, the .NET Micro Framework running directly on targeted hardware requires less than 100KB of RAM The smallest currently available module with the.NET Micro Framework built in is a headless device with a 72MHz ARM7 Core, 96KB RAM, 512KB Flash memory, and a power consumption of 10mA with all hardware components enabled.

The .NET Micro Framework requires a 32-bit processor. Although common embedded programming in assembly language or C still takes place on 16-bit or even 8-bit processors, improved production techniques have reduced the manufacturing costs and power requirements of 32-bit processors. However, the fact that the .NET Micro Framework does not require an MMU means it can run on less expensive processors than Windows CE can.

What the Framework Is Not
The .NET Micro Framework is not a real-time system. Although it is very fast and suitable for most applications, do not expect real-time deterministic behavior. A timer event might not be triggered exactly after the specified amount of time (varying by some milliseconds), or the runtime environment might take a few milliseconds to react to an interruption provoked by an interrupt service routine. Also, the garbage collector will run to free unused memory when memory gets low. Garbage collection might block all threads for a few milliseconds. You should also be aware that executing managed code is a bit slower than executing native code. With the .NET Micro Framework, all managed code is interpreted. There is no just-in-time compiler that compiles managed code parts to native machine code on the first execution, as there is for the full .NET Framework and .NET Compact Framework.

Downloading a Free Development Environment
The .NET Micro Framework SDK is available for download at no cost. To develop for the .NET Micro Framework, you need Microsoft Visual Studio 2008. It is also possible to use the free Express Editions for Visual C#. The .NET Micro Framework is a free add-in that can be integrated with the free Express Edition of Microsoft Visual Studio development environment. You can find more information and a download link at www.microsoft.com/express/vcsharp/Default.aspx.
Combining these development tools with the extensible hardware emulator of the .NET Micro Framework SDK enables you to start playing around immediately with the .NET Micro Framework—at no cost.

Licensing the .NET Micro Framework
A fee is charged for each device containing the .NET Micro Framework, but the fee is lower than the one for Windows CE. Also, you are not required to pay the fee directly. When you buy ready-to-use prebuilt modules or development boards containing the .NET Micro Framework, the license fee has already been paid to Microsoft. At time of I write this, Microsoft is changing the license model, moving the product from a revenue model to an “open” model. This means the platform is owned and maintained mainly by Microsoft, which will release nearly all the source of the base class library, tools, and porting kit to the public to make the platform broadly accessible. Microsoft will accept contributions from the community, and there will no longer be a runtime fee per device.

Source of Information : Apress Expert Dot NET Micro Framework 2nd Edition (09-2009)


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