User manual

LPC3250 Developer’s Kit v2 - User’s Guide
Page 34
Copyright 2013 © Embedded Artists AB
GPIO42
GPO_14. Not used for USB1 interface
GPIO51
SPI2_DATIN. Not used for USB1 interface
GPIO52
GPIO_04. Not used for USB1 interface
GPIO53
SPI2_CLK. Not used for USB1 interface
GPIO46
P0.6 normally not connected. Not used for USB1 interface
GPIO43
GPI_03 normally not connected. Not used for USB1 interface
4.20.1 USB Channel 1 as USB Host
When USB channel #1 is used as USB Host, 15Kohm pull-down resistors are needed on the USB data
signals. These are activated inside the USB OTG chip (U31), and this has to be done via the I2C
interface of GPIO52/GPIO53.
J20 is the connector to use when USB Host is used. In order to provide +5V to the external USB
device connected to this connector (J20), channel A of U20 must be enabled. It is enabled by default
since SJ5 is normally connected between pin 1-2. LED34 lights green when +5V is available on J20.
JP15 shall not be inserted. JP16 has no effect.
4.20.2 USB Channel 1 as USB Device
When USB channel #1 is used as USB Device, a 1.5Kohm pull-up resistor is needed on the USB DP
data signal. There are two methods to create this. JP15 is inserted and the pull-up resistor is always
enabled. Alternatively, the pull-up resistor is activated inside the USB OTG chip (U31), and this has to
be done via the I2C interface of GPIO52/GPIO53. In the latter case, JP15 shall not be inserted.
J19 is the connector to use when USB Device is used. Normally it should be a USB-B connector for
creating a USB Device interface, but the mini-AB connector can also be used in this case. The status
of VBUS can be read via U31.
JP16 shall not be inserted.
LED34 is has no meaning.
4.20.3 USB Channel 1 as USB OTG
When USB channel #1 is used as USB OTG, pull-up and pull-down resistors are controlled via the
USB OTG chip (U31), and this has to be done via the I2C interface of GPIO52/GPIO53. Note that
some LCD signals interfere with the I2C signals to the USB OTG chip. In particular note that R163 is
typically not mounted on the OEM Base Board.
J19 is the connector to use when USB OTG is used. VBUS is controlled via U31.
JP15 shall not be inserted.
LED34 is has no meaning.
JP16 can be inserted in order to force USB Host behavior on the interface (if the external device
connected to J19 cannot pull the ID signal low).