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UM10375
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© NXP B.V. 2011. All rights reserved.
User manual
Rev. 3 — 14 June 2011
140 of 368
NXP Semiconductors
UM10375
Chapter 10: LPC13xx USB device controller
For an OUT transaction, the USB ATX receives the bi-directional USB_DP and USB_DM
signals of the USB bus. The Serial Interface Engine (SIE) receives the serial data from the
ATX and converts it into a parallel data stream. The parallel data is written to the
corresponding endpoint buffer.
For IN transactions, the SIE reads the parallel data from the endpoint buffer in EP_RAM,
converts it into serial data, and transmits it onto the USB bus using the USB ATX.
Once data has been received or sent, the endpoint buffer can be read or written. The CPU
transfers data between RAM and the endpoint buffer using the register interface. See
Section 10.13 “Functional description”
for a detailed description.
10.8 Pin description
The device controller can access one USB port.
10.9 Clocking and power control
This section describes the clocking and power management features of the USB Device
Controller.
10.9.1 Power requirements
The USB protocol insists on power management by the device. This becomes very critical
if the device draws power from the bus (bus-powered device). The following constraints
should be met by a bus-powered device:
1. A device in the non-configured state should draw a maximum of 100 mA from the bus.
2. A configured device can draw only up to what is specified in the Max Power field of
the configuration descriptor. The maximum value is 500 mA.
3. A suspended device can draw a maximum of 500
A.
10.9.2 Clocks
The USB device controller clocks are shown in
Table 160. USB device pin description
Name
Direction
Description
V
BUS
I
V
BUS
status input. When this function is not enabled
via its corresponding IOCONFIG 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.