UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
574 of 1269
NXP Semiconductors
UM10503
Chapter 23: LPC43xx USB0 Host/Device/OTG controller
# Packets Occurred > 0 AND # Packets Occurred < MULT.
•
CRC Error [Transaction Error bit is set]
Remark:
For ISO, when a dTD is retired, the next dTD is primed for the next frame. For
continuous (micro) frame to (micro) frame operation the DCD should ensure that the dTD
linked-list is out ahead of the device controller by at least two (micro) frames.
23.10.9.1 Isochronous pipe synchronization
When it is necessary to synchronize an isochronous data pipe to the host, the (micro)
frame number (FRINDEX register) can be used as a marker. To cause a packet transfer to
occur at a specific (micro) frame number [N], the DCD should interrupt on SOF during
frame N-1. When the FRINDEX = N -1, the DCD must write the prime bit. The device
controller will prime the isochronous endpoint in (micro) frame N–1 so that the device
controller will execute delivery during (micro) frame N.
Remark:
Priming an endpoint towards the end of (micro) frame N-1 will not guarantee
delivery in (micro) frame N. The delivery may actually occur in (micro) frame N+1 if the
device controller does not have enough time to complete the prime before the SOF for
packet N is received.
23.10.9.2 Isochronous endpoint bus response matrix
[1]
BS error = Force Bit Stuff Error
[2]
NULL packet = Zero length packet.
Table 446. Isochronous endpoint bus response matrix
Token
type
STALL
Not primed
Primed
Underflow
Overflow
Setup
STALL
STALL
STALL
n/a
n/a
In
NULL
packet
NULL packet
Transmit
BS error
n/a
Out
Ignore
Ignore
Receive
n/a
Drop packet
Ping
Ignore
Ignore
Ignore
Ignore
Ignore
Invalid
Ignore
Ignore
Ignore
Ignore
Ignore