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USB Interface

BCM4354 Data Sheet

BROADCOM CONFIDENTIAL

Broadcom®

October 15, 2014 • 4354-DS109-R

Page 53

USB Interface

Features

The following USB interface features are supported:

• 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

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.

USB Compounded Device

Hub Controller

USB Device 1

HID Keyboard

USB Device 2

HID Mouse

USB Device 3

Bluetooth

Host

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