User guide

C M M - 52259 J U N E 1 1 , 2 0 1 0
U S E R G U I D E
11
Device Mode
The CMM-52259 may act as either a bus-powered or a self-powered device. As a bus-
powered device, the CMM-52259 will take input voltage and current through the USB connec-
tor. As a self-powered device, the CMM-52259 must be powered through the barrel connector.
The VBUS input is designed to prevent back-driving VBUS if the board is powered externally.
Connecting a mini-B cable to the CMM-52259 signals the user application to configure as a
USB Device. In this configuration, VBUS output is disabled and the CMM-52259 may be po-
wered from the USB bus. The user application must take care not to enable VBUS output to
prevent damage to the CMM-52259 or USB HOST.
As a USB Device, pull-ups on DM and DP determine USB communications speed. Enabling
the DP pull-up selects full-speed mode while enabling the DM pull-up selects low-speed.
On-The-Go Mode
The On-The-Go supplement (OTG) to the USB2.0 specification enables dual role operation.
An OTG appliance can take on HOST mode and DEVICE mode operations based on the type
of cable attached. An OTG appliance can also switch modes during a USB session using the
Host Negotiation Protocol (HNP) and Session Request Protocol (SRP) application program-
ming interface (API). The CMM-52259 is designed to allow user applications to sense the ID
pin voltage level when a USB cable is attached.
Figure 3 below shows the control signals associated with HOST and DEVICE Mode.
Figure 3: USB Configuration
USB
Signal
Function
Control Signal
Host
Mode
Device
Mode
DM
USB data(-) signal
USB_DM
DM
DM
DP
USB data(+) signal
USB_DP
DP
DP
DM Pull
Down
DM pull-down control
USB_DM_PDOWN/PQS5
Applied
NA
DP Pull
Down
DP pull-down control
USB_DP_PDOWN/PQS6
Applied
NA
DM Pull-
Up
DM pull-up control
PUC2
NA
Applied for
low-speed
DP Pull-
Up
DP pull-up control
PUB3
Na
Applied for
high-speed
VBUS /
USB ID
Sense/Enable VBUS
output
USB_BVUSCHG/PUC3
Low
High
VBUS
FAULT
Indicate VBUS fault
TP5
NA
NA
NOTE: The customer must apply a jumper wire between TP5 and an IO header signal to
access the VBUS over-current indicator signal.