Datasheet

4–12
4.3 Isochronous Transmit (Host Bus to TSB12LV01B)
The format of the isochronous-transmit packet is shown in Figure 4–17 and is described in Table 4–5. The
data for each channel must be presented to the isochronous-transmit FIFO interface in this format in the
order that packets are to be sent. The transmitter requests the bus to send any packets available at the
isochronous-transmit interface immediately following reception or transmission of the cycle-start message.
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
chanNum spd sy
isochronous data
dataLength
TAG
Reserved
Figure 4–17. Isochronous-Transmit Format
Table 4–5. Isochronous-Transmit Functions
FIELD NAME DESCRIPTION
dataLength The dataLength field indicates the number of bytes in the current packet.
TAG The TAG field indicates the format of data carried by the isochronous packet (00 = formatted,
01 – 11 are reserved).
chanNum The chanNum field carries the channel number with which the current data is associated.
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).
sy The sy field carries the transaction layer-specific synchronization bits.
isochronous data The isochronous data field contains the data to be sent with the current packet. The first byte of
data must appear in byte 0 of the first quadlet of this field. If the last quadlet does not contain four
bytes of data, the unused bytes should be padded with zeros.
4.4 Isochronous Receive (TSB12LV01B to Host Bus)
The format of the isochronous-receive data is shown in Figure 4–18 and is described in Table 4–6. The data
length, which is found in the header of the packet, determines the number of bytes in an isochronous packet.
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
chanNum
tCode
sy
isochronous data
dataLength
TAG
PacCom
spd WriteCount errCode1010
Figure 4–18. Isochronous-Receive Format