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Chapter 3
USB Interfaces (J18A/B, J13A/B)
The I/O Hub (82801DBM) provides the USB solution for both legacy UHCI controllers and EHCI
controller (USB 2.0) support. The Southbridge contains port-routing logic that determines which
controller (UHCI or EHCI) handles the USB data signals. The PC-style (or Standard) connector
(J18A/B) provides two of the four USB ports (USB0 and USB1). The other two USB ports share a
single 10-pin header (J13A/B) on the board.
USB 2.0 Support
The Southbridge contains an Enhanced Host Controller Interface (EHCI) compliant host controller,
which supports up to 4 high-speed USB 2.0 Specification compliant root ports. The higher speed USB
2.0 specification allows data transfers up to 480 Mbps using the same pins as the 4 Full-speed/Low-
speed USB UHCI ports. The Southbridge port-routing logic determines which of the controllers (UHCI
or the EHCI) processes the USB signals.
•
One EHCI host controller for all four USB ports on connectors (J18A/B, and/or J13A/B)
•
Supports USB v2.0 Specification
•
Over-current fuses, located on the board, where USB0 and USB1 share a single fuse (F1) and
USB2 and USB3 share a single fuse (F2). See Table 2-4.
Legacy USB Support
The Southbridge supports two USB Universal Host Controller Interfaces (UHCI) and each Host
Controller includes a root hub with two separate USB ports each, for a total of 4 USB ports. The USB
Legacy features implemented in the USB ports include the following:
•
One root hub and two USB ports on connector (J18A/B)
• One root hub and two USB ports on connector (J13A/B)
•
Supports USB v.1.1 and UHCI v.1.1 with integrated physical layer transceivers
• Supports improved arbitration latency for UHCI controllers
• UHCI controllers support Analog Front End (AFE) embedded cell instead of USB I/O buffers to
allow for USB High-speed signaling rates
•
Over-current fuses, located on the board, are used on all four USB ports
Primary USB0 and USB1 (J18A/B)
Table 3-11. USB 1 & 2 Interface Pin/Signal Descriptions (J18A/B)
Pin #
Signal
1
+5V
2
USBP0-
3
USBP0+
4
GND
5
+5V
6
USBP1-
7
USBP1+
8
GND
Notes: The shaded area denotes power or ground.
40
Description
+5V through a fuse (F1)
Universal Serial Bus Port 0 Data Negative
Universal Serial Bus Port 0 Data Positive
Goes to ground thorough a choke
+5V through a fuse (F1)
Universal Serial Bus Port 1 Data Negative
Universal Serial Bus Port 1 Data Positive
Goes to ground thorough a choke
Reference Manual
Hardware
ReadyBoard 800
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