TSB12C01APZ datasheet(32/59 Pages) TI

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4–2

4.1.2

Block Transmit

The block-transmit format is shown in Figure 4–2. The first quadlet contains packet-control information. The

second and third quadlets contain the 64-bit address. The first 16 bits of the fourth quadlet contains the

dataLength field. This is the number of bytes of data in the packet. The remaining 16 bits represent the

extended_tCode field. (See Table 6–11 of the IEEE 1394-1995 standard for more information on

extended_tCodes.) The block data, if any, follows the extended_tCode. Block write responses are identical

to the quadlet write response and use the format described in subsection 4.1.3.

1 2 3

5 6 7

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

spd

tLabel

tCode

priority

destinationID

destinationOffsetHigh

destinationOffsetLow

dataLength

extended_tCode

block data

Figure 4–2. Block-Transmit Format

Table 4–2. Block-Transmit Format Functions

FIELD NAME

DESCRIPTION

spd

This field indicates the speed at which this packet is to be sent. 00 = 100 Mb/s, 01 = 200 Mb/s,

and 10 = 400 Mb/s, and 11 is undefined for this implementation.

tLabel

This field is the transaction label, which is a unique tag for each outstanding transaction

between two nodes. This is used to pair up a response packet with its corresponding request

packet.

The retry code for this packet is 00 = new, 01 = retry_X, 10 = retryA, and 11 = retryB.

tCode

tCode is the transaction code for this packet (see Table 6–10 of IEEE 1394-1995 standard).

priority

The priority level for this packet. For cable implementation, the value of the bits must be 0.

For backplane implementation, see clause 5.4.1.3 and 5.4.2.1 of the IEEE 1394-1995

standard.

destinationID

This is the concatenation of the 10-bit bus number and the 6-bit node number that forms the

node address to which this packet is being sent.

destination OffsetHigh,

destination OffsetLow

The concatenation of these two fields addresses a quadlet in the destination node’s address

space. This address must be quadlet aligned (modulo 4). The upper four bits of the

destination OffsetHigh field are used as the response code for lock-response packets and

the remaining bits are reserved.

dataLength

The number of bytes of data to be transmitted in the packet.

extended_tCode

This field is the block extended_tCode to be performed on the data in this packet. See Table

6–11 of the IEEE 1394-1995 standard.

block data

The data to be sent. If dataLength is 0, no data should be written into the FIFO for this field.

Regardless of the destination or source alignment of the data, the first byte of the block must

appear in byte 0 of the first quadlet.

4.1.3

Quadlet Receive

The quadlet-receive format is shown in Figure 4–3. The first 16 bits of the first quadlet contain the destination

node and bus id, and the remaining 16 bits contain packet-control information. The first 16 bits of the second

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