Setup:
- VS Code - NRF Connect v 2.1.0
- Hardware: NRF52840-DK @ 1.8V
- Application: BLE Beacon (https://github.com/zephyrproject-rtos/zephyr/tree/main/samples/bluetooth/beacon)
KConfig/prj.conf:
CONFIG_BT=y CONFIG_BT_DEBUG_LOG=n CONFIG_BT_DEVICE_NAME="MyName" CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y CONFIG_CLOCK_CONTROL_NRF_K32SRC_XTAL=n CONFIG_BOARD_ENABLE_DCDC=y
I have disabled the LFXTAL and enabled the RC Oscillator as the clock source to reduce startup time, however from cold boot I am seeing a ~430ms period of inactivity that is running @ 4mA.
If I change my clock settings back to use the XTAL then another 400ms (expected) period is added for a total of 800ms of no BLE activity:
Yes I have powered cycled after programming. Yes I have performed a Pristine build.
When I load up the same BLE Beacon firmware from NRF5 SDK with the same clock settings, I DO NOT see this 400+ms delay. This looks to be specific to NCS/Zephyr.
Screenshot of NRF5 SDK sample code with RC oscillator as soft device clock:
I saw this post: nRF52840 startup delay
However this setting: CONFIG_ENTROPY_CC3XX=n causes a build error.
Any idea why the default NCS/Zephyr implementation for the BLE Beacon has this 400+ms delay before any BLE beacons are sent and why its at ~4mA?
Is there some additional KConfig setting I need to change?
