BCM20705 Datasheet, PDF (33/67 Pages) Cypress Semiconductor – Single-Chip Bluetooth Transceiver and Baseband Processor

BCM20705 Data Sheet
USB Interface
The USB device, configuration, and string descriptors are fully programmable, allowing manufacturers to
customize the descriptors, including vendor and product IDs, the BCM20705 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
Interface 1
Interface 2
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.
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).
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 Hub and UHE Support
The BCM20705 supports the USB hub and device model (USB, Revision 2.0, full-speed compliant). Optional
mouse and keyboard devices utilize Broadcom’s proprietary USB HID Emulation (UHE) architecture, which
allows these devices appear as standalone HID devices even though connected through a Bluetooth link.
The presence of UHE devices requires the hub to be enabled. The BCM20705 cannot appear as a single
keyboard or a single mouse device without the hub. Once either mouse or keyboard UHE device is enabled, the
hub must also be enabled.
When the hub is enabled, the BCM20705 handles all standard USB functions for the following devices:
• HID keyboard
• HID mouse
• Bluetooth
All hub and device descriptors are firmware-programmable. This USB compound device configuration (see
Figure 6 on page 31) supports up to three downstream ports. This configuration can also be programmed to a
single USB device core. The device automatically detects activity on the USB interface when connected.
Therefore, no special configuration is needed to select HCI as the transport.
The hub’s downstream port definition is as follows:
• Port 1 USB lite device core (for HID applications)
• Port 2 USB lite device core (for HID applications)
• Port 3 USB full device core (for Bluetooth applications)
When operating in Hub mode, all three internal devices do not have to be enabled. Each internal USB device
can be optionally enabled. The configuration record in NVRAM determines which devices are present.
Broadcom®
Bluetooth Transceiver and Baseband Processor
November 13, 2014 • MCS20705-DS104-R
Page 32
BROADCOM CONFIDENTIAL