UM10503
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
552 of 1269
NXP Semiconductors
UM10503
Chapter 23: LPC43xx USB0 Host/Device/OTG controller
23.8.1.6 Split state machines
The start and complete split operational model differs from EHCI slightly because there is
no bus medium between the EHCI controller and the embedded Transaction Translator.
Where a start or complete-split operation would occur by requesting the split to the HS
hub, the start/complete split operation is simply an internal operation to the embedded
Transaction Translator. The following table summarizes the conditions where handshakes
are emulated from internal state instead of actual handshakes to HS split bus traffic.
23.8.1.7 Asynchronous Transaction scheduling and buffer management
The following USB 2.0 specification items are implemented in the embedded Transaction
Translator:
1.
USB 2.0 specification, section 11.17.3
: Sequencing is provided & a packet length
estimator ensures no full-speed/low-speed packet babbles into SOF time.
2.
USB 2.0 specification, section 11.17.4
: Transaction tracking for 2 data pipes.
3.
USB 2.0 specification, section 11.17.5
: Clear_TT_Buffer capability provided though
the use of the TTCTRL register.
23.8.1.8 Periodic Transaction scheduling and buffer management
The following USB 2.0 specification items are implemented in the embedded Transaction
Translator:
1.
USB 2.0 specs, section 11.18.6.[1-2]
:
–
Abort of pending start-splits:
EOF (and not started in micro-frames 6)
Idle for more than 4 micro-frames
–
Abort of pending complete-splits:
EOF
Idle for more than 4 micro-frames
2.
USB 2.0 specs, section 11.18.6.[7-8]
:
–
Transaction tracking for up to 16 data pipes:
–
Complete-split transaction searching:
Table 433. Split state machine properties
Condition
Emulate TT response
Start-split
All asynchronous buffers full.
NAK
All periodic buffers full.
ERR
Success for start of Async. Transaction.
ACK
Start Periodic Transaction.
No Handshake (Ok)
Complete-split
Failed to find transaction in queue.
Bus Time Out
Transaction in Queue is Busy.
NYET
Transaction in Queue is Complete.
[Actual Handshake from
LS/FS device]