Driver design of bidirectional transmission equipment based on IEEE1394b

Most of the existing data transmission interface buses are relatively expensive, and it is difficult to meet the requirements for the transmission rate in practical use, which has become a major barrier hindering the performance improvement of the entire system. IEEE-1394 is one of the highest speed serial bus interfaces today. IEEE1394lb is faster than the original IEEE1394 and supports longer distances. It has a wide range of applications in real-time batch data transmission.

Based on the 1394 transmission system device driver literature, most of them are based on IEEE1394a, and IEEE1394b shows greater charm at its higher speed, which is of great significance for real-time mass data transmission, but Microsoft does not provide 1394b Support, 1394 that comes with Windows cannot support the speed of its S800, so 1394b is limited in applications, Unibrian provides the FireAPI SDK development kit, provides full support for 1394b, and is now the only driver development kit that supports 1394b .

1 IEEEl394 serial bus overview

IEEE1394, also known as Fire Wire, is a high-quality, high-speed serial bus technology developed by Apple Computer in the United States. In 1995, IEEE officially recognized the IEEE139 4-1995 specification, and in 2000, the IEEE1394a-2000 specification was launched. In 2002, the transmission rate of IEEE1394b-2002 was up to 3.2 Gb · s-1, compatible with IEEE1394a, but the shape of the interface changed from 6 Pin of IEEE1394a to 9 Pin. The main features of IEEE1394 are as follows:

(1) High-speed upgradeable, supporting transmission rates of 100 Mb · s-1, 200 Mb · s-1, and 400 Mb · s-1. IEEE1394b increases the transmission rate of 800 Mb · s-1, 16 00 bib · s-1, 3 200 Mb · s-1, and the chips available on the market now support up to 800 Mb · s-1.

(2) Support point-to-point transmission, each node can perform transactions independently from the host.

(3) Support long-distance transmission; the distance between IEEE1394 nodes cannot exceed 4.5 m. The maximum distance of IEEE1394b can reach 100 m, and more transmission media can be selected, such as unshielded category 5 twisted pair, plastic optical fiber and glass optical fiber.

(4) Support plug and play, you can add or delete devices to IEEE1394 network at any time.

(5) Hot swap, you can add and remove devices without powering off the system.

(6) Two types of transactions are supported, including IsochrONous and Asynchronous transactions.

(7) Topological structure, tree or daisy chain topology is adopted between devices, and each bus can connect up to 63 devices.

(8) Fair arbitration means that isochronous transmission has a higher priority, and asynchronous transmission can also obtain fair access to the bus.

2 The basic structure of IEEE1394b driver

The Unibrianl394 driver stack uses a top-down architecture. The core of this stack is the 1394 class driver, which completes all things in 1394 and provides all services required by the application. And this 1394 class driver is exactly the class driver in WDM driver. Figure 1 shows the Unibrainl394 driver stack.


Figure 1 Un ibra in1394 driver stack

3 Concrete realization of IEEE1394b driver

3.1 Driver entry point

The first thing to use FireAPI is to call C1394IniTIaliza. C1394IniTIalize performs all the necessary actions for 1394 initialization support. This function will check whether the FireAPI driver stack is fully installed, whether the corresponding driver has started, and the internal structure required to initialize the driver stack. .

3.2 How to open the device

When one or more devices are added or deleted on the 1394 bus, the physical device address is automatically reconfigured to support the plug-and-play feature. At this time, the physical ID of the device is reassigned, and the node number of the device may change. However, 1394 requires each node to have a globally unique identifier GUID, which is stored in Bus_Into_Block, which is unique throughout the lifetime of the device, so open the device handle in the program according to the device's GUID, and its transmission will be Don't worry about bus reset and physical ID change.

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