Datasheet

4–8
Table 4–3. Quadlet-Receive Format Functions
FIELD NAME DESCRIPTION
PacCom Packet Complete. When PacCom = 1, the current block of data is the last one for the packet.
When PacCom = 0, the current block of data is just another block of the current packet.
spd The spd field indicates the speed at which the current packet is to be sent (00 = 100 Mbits/s,
01 = 200 Mbits/s, and 10 = 400 Mbits/s, and 11 is undefined).
WriteCount WriteCount indicates the number of data quadlets in the packet.
tCode The tCode field is the transaction code for the current packet (See Table 6–10 of IEEE
1394
-1995 standard).
ackSent This 5-bit field holds the acknowledge code sent by the receiver for the current packet (See
Table 6–13 of the IEEE 1394
-1995 standard).
destinationID The destinationID field is the concatenation of the 10-bit bus number and the 6-bit node
number that forms the destination node address of the current packet.
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 is the retry code for the current packet is: 00 = new, 01 = retry_X, 10 = retryA, and
11 = retryB.
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 clause 5.4.1.3 and
5.4.2.1 of the IEEE 1394
-1995 standard).
sourceID This is the node ID (bus ID and physical ID) of the sender of this packet.
destination OffsetHigh,
destination OffsetLow
The concatenation of these two fields addresses a quadlet in the destination node address
space. This address must be quadlet aligned (modulo 4).
rCode
Specifies the result of the read request transaction. The response codes that may be returned
to the requesting agent are defined as follows:
Response
Code
Name Description
0 resp_complete Node successfully completed requested operation.
1–3 Reserved
4 resp_conflict_error Resource conflict detected by responding agent.
Request may be retried.
5 resp_data_error Hardware error. Data not available.
6 resp_type_error Field within request packet header contains
unsupported or invalid value.
7 resp_address_error Address location within specified node not
accessible.
8 – Fh Reserved
quadlet data For write requests and read responses, the quadlet data field holds the data to be transferred.
For write responses and read requests, this field is not used and should not be written into the
FIFO.