CYW20706
3.4 Link Control Layer
The link control layer is part of the Bluetooth link control functions that are implemented in dedicated logic in the link control unit (LCU).
This layer consists of the command controller that takes commands from the software, and other controllers that are activated or
configured by the command controller, to perform the link control tasks. Each task performs a different state in the Bluetooth Link
Controller.
■ Major states:
❐ Standby
❐ Connection
■ Substates:
❐ Page
❐ Page Scan
❐ Inquiry
❐ Inquiry Scan
❐ Sniff
3.5 Test Mode Support
The CYW20706 fully supports Bluetooth Test mode as described in Specification of the Bluetooth Core v4.2, which includes the
transmitter tests, normal and delayed loopback tests, and reduced hopping sequence. In addition to the standard Bluetooth Test Mode,
the CYW20706 also supports enhanced testing features to simplify RF debugging and qualification and type-approval testing,
including:
■ Fixed frequency carrier wave (unmodulated) transmission
❐ Simplifies some type-approval measurements (Japan)
❐ Aids in transmitter performance analysis
■ Fixed frequency constant receiver mode
❐ Receiver output directed to I/O pin
❐ Allows for direct BER measurements using standard RF test equipment
❐ Facilitates spurious emissions testing for receive mode
■ Fixed frequency constant transmission
❐ 8-bit fixed pattern, PRBS-9, or PRBS-15
❐ Enables modulated signal measurements with standard RF test equipment
3.6 Power Management Unit
The Power Management Unit (PMU) provides power management features that can be invoked through power management registers
or packet handling in the baseband core. This section contains descriptions of the PMU features.
3.6.1 RF Power Management
The BBC generates power-down control signals for the transmit path, receive path, PLL, and power amplifier to the 2.4 GHz trans-
ceiver. The transceiver then processes the power-down functions, accordingly.
3.6.2 SoC Power Management
The host can place the device in a sleep state, in which all nonessential blocks are powered off and all nonessential clocks are
disabled. Power to the digital core is maintained so that the state of the registers and RAM is not lost. In addition, the CYW20706
internal LPO clock is applied to the internal sleep controller so that the chip can wake automatically at a specified time or based on
signaling from the host. The goal is to limit the current consumption to a minimum, while maintaining the ability to wake up and resume
a connection with minimal latency.
If a scan or sniff session is enabled while the device is in Sleep mode, the device automatically will wake up for the scan/sniff event,
then go back to sleep when the event is done. In this case, the device uses its internal LPO-based timers to trigger the periodic wake
up. While in Sleep mode, the transports are idle. However, the device can wake up at any time. If signaled to wake up while a scan
or sniff session is in progress, the session continues but the device will not sleep between scan/sniff events. Once Sleep mode is
enabled, the wake signaling mechanism can also be thought of as a sleep signaling mechanism, since removing the wake status will
often cause the device to sleep.
In addition to a Bluetooth device wake signaling mechanism, there is a host wake signaling mechanism. This feature provides a way
for the Bluetooth device to wake up a host that is in a reduced power state.
Document Number: 002-14790 Rev. *A
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