NXP Semiconductors LPC11U1x, User Manual

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User manual Rev. 5.5 — 21 December 2016 225 of 523
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Chapter 11: LPC11U3x/2x/1x USB2.0 device controller
11.4.7 Clocking
The LPC11U3x/2x/1x USB device controller has the following clock connections:
•
USB main clock: The USB main clock is the 48 MHz +/- 500 ppm clock from the
dedicated USB PLL or the main clock (see
Table 28 ). If the main clock is used, the
system PLL output must be 48 MHz. The clock source for the USB PLL or the system
PLL must be derived from the system oscillator if the USB is operated in full-speed
mode. For low-speed mode, the IRC is suitable as the clock source.
The USB main clock is used to recover the 12 MHz clock from the USB bus.
•
AHB clock: This is the AHB system bus clock. The minimum frequency of the AHB
clock is 6 MHz when the USB device controller is receiving or transmitting USB
packets.
11.5 Pin description
The device controller can access one USB port.
11.6 Register description
Table 212. USB device pin description
Name Direction Description
V
BUS
I V
BUS
status input. When this function is not enabled
via its corresponding IOCON register, it is driven
HIGH internally.
USB_CONNECT O SoftConnect control signal.
USB_FTOGGLE O USB 1 ms SoF signal.
USB_DP I/O Positive differential data.
USB_DM I/O Negative differential data.
Table 213. Register overview: USB (base address: 0x4008 0000)
Name Access Address
offset Description Reset
value Reference
DEVCMDSTAT R/W 0x000 USB Device Command/Status
register 0x00000
800 Table 214
INFO R/W 0x004 USB Info register 0 Table 215
EPLISTSTART R/W 0x008 USB EP Command/Status List
start address 0 Table 216
DATABUFSTART R/W 0x00C USB Data buffer start address 0 Table 217
LPM R/W 0x010 USB Link Power Management
register 0 Table 218
EPSKIP R/W 0x014 USB Endpoint skip 0 Table 219
EPINUSE R/W 0x018 USB Endpoint Buffer in use 0 Table 220
EPBUFCFG R/W 0x01C USB Endpoint Buffer
Configuration register 0 Table 221
INTSTAT R/W 0x020 USB interrupt status register 0 Table 222
INTEN R/W 0x024 USB interrupt enable register 0 Table 223