Specifications

Chapter 3 Hardware
40 Reference Manual ReadyBoard 800
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 I/O Hub (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 I/O Hub 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 I/O Hub 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 2-8.
Legacy USB Support
The I/O Hub supports two USB Universal Host Controller Interfaces (UHCI) and each Host Controller
includes a root hub with two USB ports each, for a total of 4 USB ports. The USB Legacy features
implemented on 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 Description
1 VCC USB Voltage – +5V through sharedfuse (F1)
2 USBP0- Universal Serial Bus Port 0 Data Negative
3 USBP0+ Universal Serial Bus Port 0 Data Positive
4 GND Ground
5 VCC USB Voltage – +5V through shared fuse (F1)
6 USBP1- Universal Serial Bus Port 1 Data Negative
7 USBP1+ Universal Serial Bus Port 1 Data Positive
8 GND Ground
Note: The shaded area denotes power or ground.