Usb interface signals – Lantronix DSTni-EX User Manual
Page 62
54
USB Interface Signals
Clock (CLK)
The clock input is required to be connected to a 12 MHz signal that is derived
from the USB signals.
USP Speed
(SPEED)
The USB speed indicator is used by external USB transceiver logic to
determine which speed interface the USB is implementing.
1 = USB is operating at full speed.
0 = USB is a low-speed device.
USB Suspend
(SUSPND)
The USB suspend signal is used by external logic to determine when the USB
is in suspend mode. This is useful when external logic must enter a low-power
mode during suspend.
1 = USB is suspended.
0 = USB is operational.
USB Output Enable
(USBOE)
The USB output enable signal is designed to be connected to the tri-state
control of USB transceivers.
1 = USB core drives serial data on to the USB.
USB Data Plus
Output (DPO)
The USB data plus output signal transmits the NRZI-encoded serial data to
the D+ side of the USB.
USB Data Minus
Output (DMO)
The USB data minus output signal transmits the NRZI-encoded serial data to
the D- side of the USB.
USB Receive Data
(RCV)
Connects the USB receive data input to a NRZ serial data stream decoded
from the USB D+ and D- signals. Typically, this signal connects to DATAOUT
output from the digital phase lock loop. The USB core assumes that this input
signal is synchronous to the CLK signal.
USB End Of Packet
(EOP)
The USB end-of-packet input should be active when a end of packet condition
is decoded on the USB D+ and D- signals. Typically, this signal connects to
EOP output from the digital phase lock loop. The USB core assumes that this
input signal is synchronous to the CLK signal.
USB Single Ended
Zero (SE0)
The USB single-ended zero input should be active when a single-ended zero
condition decodes on the USB D+ and D- signals. Typically this signal
connects to SE0 output from the digital phase lock loop. The USB core
assumes that this input signal is synchronous to the CLK signal.
HOST Mode Enable
(HOST_MODE)
The HOST Mode Enable signal provides external programmable control of
Host Mode functions. This typically includes the pull-up/pull-down resisters
necessary to implement a USB target peripheral or a USB Host controller. For
more information on the requisite pull-up/pull-down control see USB Pull-
up/Pull-down Resistors on page 53.