Datasheet

TSB12LV32 Data Formats

SGLS139B − October 2003 − Revised April 2004TSB12LV32-EP

Table 7−4. Block Receive Format Functions

FIELD NAME DESCRIPTION

numofQuadlets Total number of quadlets in the current packet (payload and header quadlets only)

ackCode This 5-bit field holds the acknowledge code sent by the receiver for the current packet.

destinationID The destinationID field is the concatenation of the 10-bit bus number and the 6-bit node number that forms the node

address to which the current packet is being sent.

tLabel The tLabel field is the transaction label, which is a unique tag for each outstanding transaction between two nodes. This

field is used to pair up a response packet with its corresponding request packet.

rt The rt field contains the retry code for the current packet is 00 = new, 01 = retry_X, 10 = retryA, and 11 = retryB.

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

priority The priority field contains the priority level for the current packet. For cable implementation, the value of the bits must

be zero (for backplane implementation, see clauses 5.4.1.3 and 5.4.2.1 of the IEEE-1394-1995 standard).

sourceID The sourceID field contains the node ID of the sender of the current packet.

destination OffsetHigh,

destination OffsetLow

The concatenation of the destination OffsetHigh and the destination OffsetLow fields addresses a quadlet in the

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

OffsetHigh field are used as the response code for lock-response packets and the remaining bits are reserved.

dataLength For write request, read responses, and locks, the dataLength field indicates the number of bytes being transferred. For

read requests, the dataLength field indicates the number of bytes of data to be read. A write-response packet does not

use this field. Note that the number of bytes does not include the header, only the bytes of data.

extended_tCode The extended_tCode field contains the block extended_tCode to be performed on the data in the current packet (see

Table 6-11 of the IEEE 1394-1995 standard).

block data The block data field contains any data being transferred for the current packet. Regardless of the destination address

or memory alignment, the first byte of the data appears in byte 0 of the first quadlet of this field. The last quadlet of the

field is padded with zeros out to four bytes, if necessary.

spd The spd field indicates the speed at which the current packet was sent. 00 = 100 Mbps, 01 = 200 Mbps, 10 = 400 Mbs,

and 11 is undefined for this implementation.

7.2 Isochronous Transmit (Data-Mover Port to TSB12LV32)

The format of the isochronous transmit packet is shown in Figure 7−7 and is described in Table 7−5. The data

for each channel must be presented to the data-mover port in this format in the order that packets are to be

sent. The transmitter sends any packets available at the isochronous transmit interface immediately following

reception or transmission of the cycle-start message. The speed at which the current packet is sent is

determined by the speed field in the DM control register (bits 22–23). There is no FIFO in the TSB12LV32 that

supports isochronous transmit.

3210 765411109815141312 19181716 20 21 31302928272625242322

isochronous data

sytCodeTAG

dataLength

chanNum

Figure 7−7. Isochronous Transmit Format