BCM4354 Data Sheet
USB Interface
USB Interface
Features
The following USB interface features are supported:
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USB Protocol, Revision 2.0, full-speed (12 Mbps) compliant including the hub
Optional hub compound device with up to three device cores internal to device
Bus or self-power, dynamic configuration for the hub
Global and selective suspend and resume with remote wake-up
Bluetooth HCI
HID, DFU, UHE (proprietary method to emulate an HID device at system bootup)
Integrated detach resistor
Operation
The BCM4354 can be configured to boot up as either a single USB peripheral or a USB hub with several USB
peripherals attached. As a single peripheral, the host detects a single USB Bluetooth device. In hub mode, the
host detects a hub with one to three of the ports already connected to USB devices (see Figure 16).
Figure 16: USB Compounded Device Configuration
Host
USB Compounded Device
Hub Controller
USB Device 1
HID Keyboard
USB Device 2
HID Mouse
USB Device 3
Bluetooth
Depending on the desired hub mode configuration, the BCM4354 can boot up showing the three ports
connected to logical USB devices internal to the BCM4354: a generic Bluetooth device, a mouse, and a
keyboard. In this mode, the mouse and keyboard are emulated devices, since they connect to real HID devices
via a Bluetooth link. The Bluetooth link to these HID devices is hidden from the USB host. To the host, the mouse
and/or keyboard appear to be directly connected to the USB port. This Broadcom proprietary architecture is
called USB HID Emulation (UHE).
The USB device, configuration, and string descriptors are fully programmable, allowing manufacturers to
customize the descriptors, including vendor and product IDs, the BCM4354 uses to identify itself on the USB
port. To make custom USB descriptor information available at boot time, stored it in external NVRAM.
Broadcom®
October 15, 2014 • 4354-DS109-R
Page 53
BROADCOM CONFIDENTIAL
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