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UM10375
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© NXP B.V. 2011. All rights reserved.
User manual
Rev. 3 — 14 June 2011
142 of 368
NXP Semiconductors
UM10375
Chapter 10: LPC13xx USB device controller
10.9.4 Remote wake-up
The USB block supports software initiated remote wake-up. Remote wake-up involves a
resume signal initiated from the device. This is done by resetting the suspend bit in the
Device Status register. Before writing into the register,
both the USB_MainClk and
PCLK need to be enabled in the system control block
.
Before the device is suspended, it is important that the AP_CLK bit in the Set
Mode register is set. The USB PHY should not be disabled while the device is
suspended so it can continue to respond to USB bus events.
10.9.5 Interrupts
The external interrupt generation takes place only if the necessary ‘enable’ bits are set in
the Device Interrupt Enable register. The raw interrupt status will be registered in the
status register. The interrupt has to be cleared by writing ‘1’ into the interrupt clear
register.
10.10 Register description
shows the USB Device Controller registers directly accessible by the CPU. The
Serial Interface Engine (SIE) has other registers that are indirectly accessible via the SIE
command registers. See
Section 10.11 “Serial interface engine command description”
for
more information.
Fig 18. USB clocking
.
USB_NeedClk
48 Mhz
Clock control block
EN
EN
clk
USB_NeedClk
USB_MainClk
48 Mhz
pclk input
USB block
PCLK
AP_CLK
(set Mode[0])
SYSAHBCLKCTRL[14]