Embedded LPC3250 Betriebsanweisung PDF herunterladen (Seite 35)

LPC3250 Developer’s Kit v2 - User’s Guide

Page 35

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

1 2 ... 30 31 32 33 34 35 36 37 38 39 40 ... 65 66

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