Freescale Semiconductor MCF54455 Reference Manual page 236

Field
31 Reserved, must be cleared.
30–24 TT Hub Address. This field is used to match against the Hub Address field in a QH or siTD to determine if the
TTHA packet is routed to the internal TT for directly attached FS/LS devices. If the hub address in the QH or siTD
does not match this address then the packet is broadcast on the high speed ports destined for a downstream
HS hub with the address in the QH or siTD.
23–0 Reserved, must be cleared.
10.3.4.10 Master Interface Data Burst Size Register (BURSTSIZE)
This register is not defined in the EHCI specification. BURSTSIZE dynamically controls the burst size
during data movement on the initiator (master) interface.
Address: 0xFC0B_0160 (BURSTSIZE)
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
R 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
W
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0
Figure 10-26. Master Interface Data Burst Size (BURSTSIZE)
Field
31–16 Reserved, must be cleared.
15–8 Programable TX burst length. Represents the maximum length of a burst in 32-bit words while moving data from
TXPBURST system memory to the USB bus. Must not be set to greater than 16.
7–0 Programable RX burst length. This register represents the maximum length of a burst in 32-bit words while
RXPBURST moving data from the USB bus to system memory. Must not be set to greater than 16.
10.3.4.11 Transmit FIFO Tuning Control Register (TXFILLTUNING)
This register is not defined in the EHCI specification. The TXFILLTUNING register controls performance
tuning associated with how the module posts data to the TX latency FIFO before moving the data onto the
USB bus. The specific areas of performance include how much data to post into the FIFO and an estimate
for how long that operation takes in the target system.
Definitions:
T = Standard packet overhead
0
T = Time to send data payload
1
T = Total packet flight time (send-only) packet (T
s
T = Time to fetch packet into TX FIFO up to specified level
ff
T = Total packet time (fetch and send) packet (T
p
Freescale Semiconductor
Table 10-28. TTCTRL Field Descriptions
Description
Table 10-29. BURSTSIZE Field Descriptions
Description
Universal Serial Bus Interface – On-The-Go Module
Access: User read/write
9 8 7 6
TXPBURST
= T + T )
s 0 1
= T + T )
p ff s
5 4 3 2 1 0
RXPBURST
10-29