UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
596 of 1269
NXP Semiconductors
UM10503
Chapter 24: LPC43xx USB1 Host/Device controller
24.6.3 USB Status register (USBSTS)
This register indicates various states of the Host/Device controller and any pending
interrupts. Software sets a bit to zero in this register by writing a one to it.
Remark:
This register does not indicate status resulting from a transaction on the serial
bus.
15
FS2
Bit 2 of the Frame List Size bits. See
0
-
23:16
ITC
Interrupt threshold control.
The system software uses this field to set the maximum rate at which
the host/device controller will issue interrupts. ITC contains the
maximum interrupt interval measured in micro-frames. Valid values
are shown below. All other values are reserved.
0x0 = Immediate (no threshold)
0x1 = 1 micro frame.
0x2 = 2 micro frames.
0x8 = 8 micro frames.
0x10 = 16 micro frames.
0x20 = 32 micro frames.
0x40 = 64 micro frames.
0x8
R/W
31:24
-
Reserved
0
Table 461. USB Command register in host mode (USBCMD_H - address 0x4000 7140) bit description
…continued
Bit
Symbol
Value
Description
Reset
value
Access
Table 462. Frame list size values
USBCMD bit 15
USBCMD bit 3
USBCMD bit 2
Frame list size
0
0
0
1024 elements (4096 bytes) - default
value
0
0
1
512 elements (2048 bytes)
0
1
0
256 elements (1024 bytes)
0
1
1
128 elements (512 bytes)
1
0
0
64 elements (256 bytes)
1
0
1
32 elements (128 bytes)
1
1
0
16 elements (64 bytes)
1
1
1
8 elements (32 bytes)