CYW20702
5.2 HCI Transport Detection Configuration
The CYW20702 supports the following interface types for the HCI transport from the host:
■ UART (H4 and H5)
■ USB
■ SPI
Only one host interface can be active at a time. The firmware performs a transport detect function at boot-time to determine which
host is the active transport. It can auto-detect UART and USB interfaces, but the SPI interface must be selected by strapping the SCL
pin to 0.
The complete algorithm is summarized as follows:
1. Determine if SCL is pulled low. If it is, select SPI as HCI host transport.
2. Determine if any local NVRAM contains a valid configuration file. If it does and a transport configuration entry is present, select the
active transport according to entry, and then exit the transport detection routine.
3. Look for start-of-frame (SOF) on the USB interface. If it is present, select USB.
4. Look for CTS_N = 0 on the UART interface. If it is present, select UART.
5. Repeat Step 3 and Step 4 until transport is determined.
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 bootup)
■ 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 CYW20702 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
Host
USB Compounded Device
Hub Controller
USB Device 1
HID Keyboard
USB Device 2
HID Mouse
USB Device 3
Bluetooth
Document Number: 002-14773 Rev. *L
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