High frequency clock lock hotfix module

Use the high frequency clock lock hotfix module to keep the high frequency clock enabled. This reduces the latency before the first packet in a row is transmitted over Bluetooth®, but it also increases the power consumption. If this module is disabled, a startup delay of around 1.4 ms (0.85 ms in case of nRF54L Series SoCs) will be added to the overall latency of the first packet.

Note

The module is deprecated. Use the CONFIG_DESKTOP_BLE_LOW_LATENCY_LOCK) Kconfig option instead. Setting the peripheral latency Bluetooth LE connection parameter to 0 for a connection that uses Low Latency Packet Mode connection interval on peripheral leads to keeping the high frequency clock enabled. That mitigates the extra HID report latency caused by the high frequency clock startup delay.

Module events

Source Module	Input Event	This Module	Output Event	Sink Module
Power manager module	power_down_event	hfclk_lock
Source modules for module_state_event	module_state_event
Bluetooth LE advertising module	wake_up_event
Buttons module
HID forward module
Motion module
Power manager module
Wheel module
			module_state_event	Sink modules for module_state_event

Note

See the Application overview for more information about the event-based communication in the nRF Desktop application and about how to read this table.

Configuration

The module is not supported for nRF54H SoC Series (CONFIG_SOC_SERIES_NRF54HX).

Make sure that Bluetooth LE Low Latency Packet Mode (LLPM) is enabled in configuration (CONFIG_CAF_BLE_USE_LLPM). Using LLPM connection parameters reduces HID data latency far more significantly than enabling the module.

Enable the module with the CONFIG_DESKTOP_HFCLK_LOCK_ENABLE Kconfig option.

Implementation details

The high frequency clock is disabled on power_down_event and reenabled on wake_up_event. This is done to reduce the power consumption.