1394b基础学习笔记

1. STOF Packet
The CC shall transmit a start of frame packet (STOF) at a fixed frame rate ± 0.1% of the frame rate (e.g. 10 milliseconds,12.5 milliseconds, etc.). The STOF packet shall be an asynchronous stream packet transmitted on channel 31. The STOF message shall conform to Figure 1. Note that there is no Packet Header or Packet Trailer in a STOF packet.

CC应以固定帧速率±0.1%的帧速率（例如10毫秒，12.5毫秒等）。STOF分组应当是在信道31上传输的异步流分组。这个STOF消息应符合图1的规定。请注意，在STOF数据包中不存在数据包报头或数据包尾部。

FIGURE 1 - STOF PACKET

2 Asynchronous Stream Packets

Asynchronous stream packets are isochronous packets that are normally sent during the asynchronous time interval. Figure 2 shows a typical asynchronous stream packet as seen on the bus. These packets, as defined in this specification, consist of the 1394 header, inserted by the hardware, the Anonymous Subscriber Messaging Header, the Payload Data Area, the Packet Trailer, and the 1394 CRC, inserted by the hardware.

异步流数据包是在异步时间间隔期间正常发送的等时数据包。图2显示了总线上的典型异步流数据包。如本说明书中所定义的，这些分组由硬件插入的1394报头、匿名用户消息报头、有效载荷数据区、分组尾部和硬件插入的1394 CRC组成。

FIGURE 2 ASYNCHRONOUS STREAM PACKET

3 Asynchronous Transactions

Asynchronous transactions may be used when a response such as acknowledge or negative acknowledge is required. An example might be software Load or integration support messages. The asynchronous packet format is shown in Figure 3.

当需要诸如确认或否定确认之类的响应时，可以使用异步事务。例如软件加载或集成支持消息。异步数据包格式如图3所示。

FIGURE 3 - ASYNCHRONOUS TRANSACTION PACKET