IEEE 1394 SBP-2 Driver Development Concepts (Windows CE 5.0)
The ANSI Standard NCTIS 325-1999 specification defines Serial Bus Protocol 2 (SBP-2). A driver based on the SBP-2 protocol is capable of carrying traffic for many types of devices. To access an IEEE 1394 SBP-2 device, you can use the standard file system APIs, such as CreateFile.
SBP-2 is a control protocol that encapsulates transactions for commands to maximize the direct memory access (DMA) capabilities of IEEE 1394. Certain sets define the commands for these transactions. The SCSI-3 standard defines the primary command sets. All command sets contain a collection of device types that define the type of device and the commands for a particular device.
Microsoft® Windows® CE offers direct support only for the SCSI-3 command set. SCSI-3 can generate commands to make use of the following device types:
- Reduced block commands (RBC)
- Multimedia commands (MMC)
- SCSI block commands (SBC)
An SBP-2 driver can support command sets other than SCSI-3, but those command sets require a driver similar to SCSIBLK to support their generation.
The SCSI-3 command set and the RBC, SBC, and MMC device types support most block-based SBP-2 mass storage devices.
The following table shows the two modules that provide SBP-2 support.
| Module | Description |
|---|---|
| SBP-2 | The SBP-2 driver encapsulates the SBP-2 protocol and provides the SBP-2 functionality to dependent drivers. |
| SCSIBLK | The SCSIBLK driver provides a bock device interface to the system. The SCSIBLK driver processes the commands it receives into SBP-2 transactions. For example, requests for large transfers are broken into N transfers of the maximum transaction size of the given device. SCSIBLK can receive many requests asynchronously and process them in parallel. |
The following illustration shows the two modules that provide the SBP-2 support.
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SBP-2 detects devices that use the RBC, SBC, and MMC device types and exports them to the Storage Manager under the FWRX: prefix; X is an index from 0 to 9. Once the Storage Manager is available, it attempts to mount a file system against the device. For example, FATFS for a hard drive or UDFS for a DVD-ROM drive. For more information on the Storage Manager, see Storage Manager.
The exported devices respond to normal block device IOCTLs, such as IOCTL_DISK_READ or IOCTL_DISK_WRITE. For more information on block device IOCTLs, see Block Driver Interface.
You can connect or disconnect IEEE 1394 at any time. When connected, SBP-2 devices are available to file systems and applications. When disconnected, associated file systems dismount and the FWRX: device disappears.
Only unplug hard drives when you are not using the device. If you remove a device while it is in use, such as during a read or write transaction, you will not physically damage the device, but you risk corruption of the file system on the device. If a file system implements caching, flush the cache to the hard drive before you disconnect the device.
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