User manual

LPC4357 Developer’s Kit - User’s Guide
Page 34
Copyright 2013 © Embedded Artists AB
4.21 SP12: USB Channel 2
This section describes the second USB interface on the board. This interface has a USB Host
connector (USB-A), a USB OTG (USB mini-B) and a USB Device connector (USB-B). One of these
interfaces can be used at a time, i.e., both cannot be used simultaneously. The software on the
LPC4357 OEM Board is also different between the two interfaces.
This interface is connected to the USB0 interface on the LPC4357.
For USB Device operation; insert jumpers in position 1-2 in JP17/JP18/JP19. GPIO28 controls USB
connect functionality and LED32 lights when the USB Device is connected. SJ4 has pads 1-2 shorted
by default. LED33 is controlled by GPIO27 and signals USB-up state. GPIO54 is used for VBUS
sensing.
For USB Host operation; insert jumpers in position 2-3 in JP17/JP18/JP19. USB Host power is
controlled via distribution switch U20 (found in schematic page 11). Signal GPIO26 is active low and
enables +5V on VBUS2. LED35 light whenever +5V is present on VBUS2. GPIO55 is connected to
status feedback from the distribution switch. GPIO54 is used for VBUS sensing. 15Kohm pull-down
resistors are always active.
See picture below for locating relevant components. The table below lists signal connections.
Figure 22 – USB Channel#2
Signals
LPC4357
USB2-DP
USB0-DP
USB2-DM
USB0-DM
GPIO27
P9_4
GPIO28
P9_5
GPIO54
USB0_VBUS
GPIO26
inverted P2_3, the signal has been inverted to be
USB-A Connector
J22
USB-B Connector
J21
Host/Device Select
JP17
Upper: USB Device
Lower: USB Host
Host/Device Select
JP19/JP18
Left: USB Device
Right: USB Host
USB2-Up LED
LED33
USB2 VBUS Power
LED35
USB2-Connect LED
LED32
Mini-B USB Connector
J32
OTG ID
JP31