CYW20704
There are two mechanisms for the device and the host to signal wake status to each other:
USB
When running in USB mode with LPM, the device supports the USB version 2.0
full-speed specification, suspend/resume signaling, as well as remote wake-up
signaling for power control.
Bluetooth device WAKE (BT_DEV_WAKE) and The BT_DEV_WAKE signal allows the host to wake the BT device, and
Host WAKE (and BT_HOST_WAKE) signaling
BT_HOST_WAKE is an output that allows the BT device to wake the host.
Table 2. Power Control Pin Summary
Pin
Direction
Description
BT_DEV_WAKE
(BT_GPIO_0)
Host output
BT input
Bluetooth device wake-up: Signal from the host to the Bluetooth device that the host
requires attention.
■Asserted = Bluetooth device must wake up or remain awake.
■Deasserted = Bluetooth device may sleep when sleep criteria are met.
The polarity of this signal is software configurable and can be asserted high or low. By
default, BT_DEV_WAKE is active-low (if BT-WAKE is low it requires the device to wake up
or remain awake).
For USB applications, this pin can be used to disable the BT radio, which puts the device
in Airport mode.
BT_HOST_WAKE
(BT_GPIO_1)
BT output
Host input
Host wake-up. Signal from the Bluetooth device to the host indicating that Bluetooth device
requires attention.
■Asserted = Host device must wake up or remain awake.
■Deasserted = Host device may sleep when sleep criteria are met.
The polarity of this signal is software configurable and can be asserted high or low.
BT_CLK_REQ
RST_N
BT output
BT input
Clock request
■Asserted = External clock reference required
■Deasserted = External clock reference may be powered down
Used to place the chip in reset. RST_N is active-low.
3.6.3 Bluetooth Baseband Core Power Management
The following are low-power operations for the Bluetooth Baseband Core (BBC):
■ Physical layer packet-handling turns the RF on and off dynamically within transmit/receive packets.
■ Bluetooth-specified low-power connection modes: sniff, hold, and park. While in these modes, the CYW20704 runs on the low-power
oscillator and wakes up after a predefined time period.
3.7 Adaptive Frequency Hopping
The CYW20704 supports host channel classification and dynamic channel classification Adaptive Frequency Hopping (AFH)
schemes, as defined in the Bluetooth specification.
Host channel classification enables the host to set a predefined hopping map for the device to follow.
If dynamic channel classification is enabled, the device gathers link quality statistics on a channel-by-channel basis to facilitate chan-
nel assessment and channel map selection. To provide a more accurate frequency hop map, link quality is determined using both RF
and baseband signal processing.
Document Number: 002-14786 Rev. *E
Page 11 of 49
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