Hardware Manual - RTD Embedded Technologies, Inc.

Board Functionality
Block Diagram
Below is a block diagram of the CM17047. Primary board components are in bold, while external
I/O connections are italicized.
CM17047 Block Diagram
USB
Port 1
USB
Port 2
USB
Port 3
USB
Port 4
USB
Port 5
NEC µPD720101
USB Controller
USB Routing Logic
EHCI Core
(Ports 1 through 5)
OHCI Core #1
(Ports 1, 3, and 5)
OHCI Core #2
(Ports 2 and 4)
PCI Arbiter
PCI Bus
USB Controller Cores
The CM17407 uses the NEC µPD720101 USB 2.0 Host Controller. It is a standard PCI USB 2.0
controller, and is compatible with all USB 2.0-compliant devices. As per the USB 2.0
specification, it is fully backwards compatible with USB 1.1 and 1.0 devices.
The NEC µPD720101 includes three USB controller cores. The primary core is an Enhanced
Host Controller Interface (EHCI), which provides high-speed USB 2.0 connections to all 5 ports.
The other two cores are Open Host Controller Interface (OHCI) cores, which provide full-speed
and low-speed connections to the ports. Which core is used will be determined dynamically by
the USB routing logic.
When a USB device is attached, the NEC µPD720101 detects the speed of the device. If it is a
high-speed USB 2.0 device, the EHCI core will be used for that port. If a full-speed or low-speed
device is connected, one of the OHCI cores will be used for that port. This approach allows
slower USB devices to be attached without affecting the performance of faster ones.
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