NRF52840 ble_App_uart_c example hangs in first start and debug mode (SDK 17.1.0)

[Yogeshwaran]

I am using ble_app_uart_c example to scan nrf beacons. Facing strange issue with debugger.

Enabled RTT and disable UART Logs, when i connect debugger and put break point after ble_stack_init() call then debugger get struck at SVCALL(SD_SOFTDEVICE_ENABLE, uint32_t, sd_softdevice_enable(nrf_clock_lf_cfg_t const * p_clock_lf_cfg, nrf_fault_handler_t fault_handler));

But if disconnect debugger and do hard reset things are fine. 

What could be the reason behind this issue?

[run_ar]

Hi,

Not sure exactly where you put your break-point. But the SoftDevice has real-time requirements, so if you halt it you will end up with an assert quite fast. For debugging when running the sd, I would recommend that you mainly use logging.

[Yogeshwaran]

Actually SVCALL is returning NRF_INVALID_STATE error.

It means that the soft device initialized already is it so?

But again if do hard reset device works fine.

[Yogeshwaran]

in debug mode system is not getting out of SVCALL(SD_SOFTDEVICE_ENABLE, uint32_t, sd_softdevice_enable(nrf_clock_lf_cfg_t const * p_clock_lf_cfg, nrf_fault_handler_t fault_handler));

any solution?

[run_ar]

Yes, it likely does. Please check your code to see where you could be initializing this earlier.

[run_ar]

You cannot debug while the SD is running. The SD has internal events that are timing critical, halting the cpu will lead to an assert.