User manual

Advantech SOM-Express Design Guide
Chapter 5 Carrier Board Design Guidelines 47
5.2 Universal Serial Bus (USB)
The Universal Serial Bus (USB) provides a bi-directional, isochronous, hot-attachable
Plug and Play serial interface for adding external peripheral devices such as game
controllers, communication devices and input devices on a single bus. SOM-Express
modules provide several USB 2.0 ports.
USB stands for Universal Serial Bus, an industry-standard specification for attaching
peripherals to a computer. It delivers high performance, the ability to plug in and
unplug devices while the computer is running, great expandability, and a wide variety
of solutions.
5.2.1 Signal Description
Table 5.9 shows SOM-Express USB signals, including pin number, signals, I/0 and
descriptions.
Table 5.9 USB Signals Description
Pin Signal I/O Description
-
-
USB[0:7]+
USB[0:7]-
I/O USB differential pairs, channels 0 through 7
B44 USB_0_1_OC# I
USB over-current sense, USB channels 0 and 1. A pull-up for this
line shall be present on the module. An open drain driver from a
USB current monitor on the Carrier Board may drive this line low.
A44 USB_2_3_OC# I
USB over-current sense, USB channels 2 and 3. A pull-up for this
line shall be present on the module. An open drain driver from a
USB current monitor on the Carrier Board may drive this line low.
B38 USB_4_5_OC# I
USB over-current sense, USB channels 4 and 5. A pull-up for this
line shall be present on the module. An open drain driver from a
USB current monitor on the Carrier Board may drive this line low.
A38 USB_6_7_OC# I
USB over-current sense, USB channels 6 and 7. A pull-up for this
line shall be present on the module. An open drain driver from a
USB current monitor on the Carrier Board may drive this line low.
5.2.2 Design Guidelines
Figure 5-6 shows USB connections for SOM-Express USB signals.
Figure 5-6 USB Connections
SOM-Express
USB
[ 0 ]
USB Connector
USB [ 0 ] -
USB [ 1 ]
USB [ 1 ] -
USB [ 2 ]
USB [2 ]-
USB [ 3 ]
USB [3 ]-