User manual

LPC4357 Developer’s Kit - User’s Guide

Page 32

4.20 SP11: USB Channel 1

The board contains two USB interfaces. This section covers the first (#1) that offers a USB Host or

USB OTG interface. Only 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 USB1 interface on the LPC4357.

There is an external USB OTG transceiver, U31. This transceiver is used for OTG specific signaling

but also for controlling the 1.5Kohm pull-up and 15Kohm pull-down resistor control that is needed for

USB Host/Device. If just USB Device is needed, it is possible to insert a jumper in JP15 to statically

connect a 1.5Kohm pull-up resistor to the USB-DP signal. LED31 can be used to signal USB-up state.

USB Host power is controlled via distribution switch U20. Pads 1-2 on SJ5 are by default connected to

always enable +5V on VBUS channel 1. LED34 light whenever +5V is present on VBUS1. VBUS

feedback via GPIO46 is by default disconnected as well as status feedback from the distribution switch

via GPIO51.

In case VBUS1 shall be actively controlled from the LPC4357 OEM Board, R190 and R198 must be

soldered and pad 2-3 on SJ5 must be connected. Further, GPIO43/46/51 must not be used for other

tasks in the design.

It is possible to force USB Host detection when using the USB OTG interface by inserting a jumper on

JP16.

See picture below for locating relevant components. The table below lists signal connections.

Figure 21 – USB Channel#1

Signals

LPC4357

USB1-DP

USB1-DM

USB-A Connector

J20

USB mini-AB Connector

J19

Force USB Host

J16

Force USB Connect

J15

MIC2555 Expansion

JP30

Power Control

SJ5

USB1-Up LED

LED31

USB1 VBUS Power

LED34