Philips Semiconductors

Preliminary specification

PDI1394L21

1394 full duplex AV link layer controller

1999 Aug 06

13

12.5

Link Packet Data Formats

The data formats for transmission and reception of data are shown below. The transmit format describes the expected organization for data

presented to the link at the asynchronous transmit, physical response, or isochronous transmit FIFO interfaces.

12.5.1

Asynchronous Transmit Packet Formats

These sections describe the formats in which packets need to be delivered to the queues (FIFOs) for transmission. There are four basic formats

as follows:

ITEM

FORMAT

USAGE

TRANSACTION CODE

(tCode)

1

No packet data

Quadlet read requests

4

1

No-packet data

Quadlet/block write responses

2

Quadlet write requests

0

2

Quadlet packet

Quadlet read responses

6

Block read requests

5

Block write requests

1

3

Block Packet

Block read responses

7

3

Block Packet

Lock requests

9

Lock responses

4

Unformatted transmit

Concatenated self-ID / PHY packets

Each packet format uses several fields (see names and descriptions below). More information about these fields (not the format) can be found

in the 1394 specification. Grey fields are reserved and should be set to zero values.

12.5.1.1

No-data Transmit

The no-data transmit formats are shown in Figures 6 and 7. The first quadlet contains packet control information. The second and third quadlets

contain 16-bit destination ID and either the 48-bit, quadlet aligned destination offset (for requests) or the response code (for responses).

destinationID

spd

tLabel

rt

tCode

0000

29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

destinationOffsetHigh

SV00250

destinationOffsetLow

0

31 30

Figure 6. Quadlet Read Request Transmit Format

destinationID

spd

tLabel

rt

tCode

0000

SV00249

29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

rCode

31 30

0

Figure 7. Quadlet/Block Write Response Packet Transmit Format