BCM20705 datasheet(21/51 Pages) CYPRESS

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Document Number: 002-14867 Rev. *F

Page 21 of 51

CYW20705

5.3 USB Interface

5.3.1 Features

The following USB interface features are supported:

■ USB Protocol, Revision 2.0, full-speed 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 wakeup

■ Bluetooth HCI

■ HID, DFU, UHE (proprietary method to emulate an HID device at system boot)

■ Integrated detach resistor

5.3.2 Operation

Note: The USB and HCI UART interfaces cannot be used simultaneously. For designs that do not use the USB interface, VDD_USB,

HUSB_DP and HUSB_DN must be connected to ground.

The CYW20705 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 6).

Figure 6. USB Compounded Device Configuration

Depending on the desired hub mode configuration, the CYW20705 can boot up showing the three ports connected to logical USB

devices internal to the CYW20705—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 Cypress 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 CYW20705 uses to identify itself on the USB port. To make custom USB descriptor information

available at boot time, stored it in external NVRAM.

Despite the mode of operation (Single Peripheral or Hub), the Bluetooth device is configured to include the following interfaces:

Interface 0

Contains a Control endpoint (Endpoint 0x00) for HCI commands, a Bulk In Endpoint (Endpoint 0x82) for receiving

ACL data, a Bulk Out Endpoint (Endpoint 0x02) for transmitting ACL data, and an Interrupt Endpoint (Endpoint

0x81) for HCI events.

Interface 1

Contains Isochronous In and Out endpoints (Endpoints 0x83 and 0x03) for SCO traffic. Several alternate Interface

1 settings are available for reserving the proper bandwidth of isochronous data (depending on the application).

Interface 2

Contains Bulk In and Bulk Out endpoints (Endpoints 0x84 and 0x04) used for proprietary testing and debugging

purposes. These endpoints can be ignored during normal operation.

USB Compounded Device

Hub Controller

USB Device 1

HID Keyboard

USB Device 2

HID Mouse

USB Device 3

Bluetooth

Host

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