UM10503
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User manual
Rev. 1.3 — 6 July 2012
522 of 1269
NXP Semiconductors
UM10503
Chapter 23: LPC43xx USB0 Host/Device/OTG controller
23.6.6 Frame index register (FRINDEX)
23.6.6.1 Device mode
In Device mode this register is read only, and the device controller updates the
FRINDEX[13:3] register from the frame number indicated by the SOF marker. Whenever a
SOF is received by the USB bus, FRINDEX[13:3] will be checked against the SOF
marker. If FRINDEX[13:3] is different from the SOF marker, FRINDEX[13:3] will be set to
the SOF value and FRINDEX[2:0] will be set to zero (i.e. SOF for 1 ms frame). If
FRINDEX [13:3] is equal to the SOF value, FRINDEX[2:0] will be incremented (i.e. SOF
for 125
s micro-frame) by hardware.
23.6.6.2 Host mode
This register is used by the host controller to index the periodic frame list. The register
updates every 125
s (once each micro-frame). Bits[N: 3] are used to select a particular
entry in the Periodic Frame List during periodic schedule execution. The number of bits
used for the index depends on the size of the frame list as set by system software in the
Frame List Size field in the USBCMD register.
This register must be written as a DWord. Byte writes produce undefined results. This
register cannot be written unless the Host Controller is in the 'Halted' state as indicated by
the HCHalted bit in the USBSTS register (host mode). A write to this register while the
Run/Stop bit is set to a one produces undefined results. Writes to this register also affect
the SOF value.
Table 406. USB frame index register in device mode (FRINDEX_D - address 0x4000 614C) bit
description
Bit
Symbol
Description
Reset value
Access
2:0
FRINDEX2_0
Current micro frame number
N/A
RO
13:3
FRINDEX13_3
Current frame number of the last frame
transmitted
N/A
RO
31:14
-
Reserved
N/A
Table 407. USB frame index register in host (FRINDEX_H - address 0x4000 614C) bit
description
Bit
Symbol
Description
Reset value
Access
2:0
FRINDEX2_0
Current micro frame number
N/A
R/W
12:3
FRINDEX12_3
Frame list current index.
N/A
R/W
31:13
-
Reserved
N/A
Table 408. Number of bits used for the frame list index
USBCMD
bit 15
USBCMD
bit 3
USBCMD
bit 2
Frame list size
N
0
0
0
1024 elements (4096 bytes). Default value.
12
0
0
1
512 elements (2048 bytes)
11
0
1
0
256 elements (1024 bytes)
10
0
1
1
128 elements (512 bytes)
9
1
0
0
64 elements (256 bytes)
8