User manual

LPC3250 Developer’s Kit v2 - User’s Guide
Page 35
Copyright 2013 © Embedded Artists AB
4.21 SP12: USB Channel 2
This section describes the second USB interface on the board. This is the interface that the USB
interface on the LPC3250 is connected to.
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 LPC3250 OEM Board is also different between the interfaces.
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. It is also possible to control the “connect functionality” via the USB OTG transceiver that is
located on the LPC3250 OEM board.
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 20 – USB Channel#2
Signals
LPC3250
USB2-DP
USB-DP from USB OTG transceiver on LPC3250 OEM board
USB2-DM
USB-DM from USB OTG transceiver on LPC3250 OEM board
GPIO27
GPO_17
GPIO28
GPO_20
GPIO54
USB-VBUS from USB OTG transceiver on LPC3250 OEM board
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