I've recently (late 2007) been playing with the .NET Micro Framework from Microsoft on the Tahoe development board from Device Solutions.net (formerly Embedded Fusion). The MicroFramework was developed for Microsoft Smart Personal Object Technology (SPOT) and Windows SideShow devices.

The Meridian module on which the Tahoe MicroFramework development kit is based includes:

• 100MHz Freescale MC9328MXS (ARM9 core)
• 16Mbit Flash memory (32Mbit option available)
• 64Mbit SDRAM at 96MHz (256Mbit option available)
• TFT LCD interface configured for Hitachi TX07D08VM1CBB 2.7" screen

To try out the platform I created a simple FAT filesystem browser and picture viewer. The user can browse a FAT filesystem and display individual pictures or alternatively select a directory and see an animated display of all pictures below that point in the filesystem. The animation dynamically scales and rotates images into and out-of the display.

The biggest task was to create a C# implementation of the FAT filesystem for the .NET Micro Framework to read data from MMC and SD cards. The code handles partitions and, both FAT16 and FAT32.

Directory entries are decoded to give attributes, file creation time and file size. Long filenames are supported and icons are provided for common file types. See photos opposite.

Additionally, byte reads are efficiently handled by read ahead and block caching. Random access to files is supported via sector and byte seek( ) routines.

The Tahoe board doesn't have an SD interface so had to make a daughter board with an SD card slot. The board also contains a Bluetooth interface but have yet to put that to good use :)

More on this soon...

Dave Baker from Microsoft
demonstrates the system during a
Windows Embedded European Tour.
Photograph by Caroline Phillips