Cannot start HF clock after release

[moon.kim]

Hi.

Device : nRF52820

SDK 17.0.2 ( Softdevice 7.2.0)

I initialized the clock as below to use USB.

ret = nrf_drv_clock_init();
APP_ERROR_CHECK(ret);

nrf_drv_clock_lfclk_request(NULL);

while(!nrf_drv_clock_lfclk_is_running())
{
    /* Just waiting */
}

ble_stack_init();
gap_params_init();
gatt_init();
advertising_init();
services_init();
conn_params_init();
peer_manager_init();

And before changing to sleep mode, the clock was stopped to minimize current consumption. And after wake-up, it tries to run the clock again.

ret_code_t err_code;

//Clock release
nrf_drv_clock_hfclk_release();

err_code = nrf_ble_lesc_request_handler();
APP_ERROR_CHECK(err_code);

//Into sleep mode
nrf_pwr_mgmt_run();

//Wake-up
nrf_drv_clock_hfclk_request(NULL);

But for some reason this doesn't work. 

How do I stop and restart the clock when using USB?

[Vidar Berg]

Hello,

Please make sure your building with the SOFTDEVICE_PRESENT flag, This flag makes it so that the clock driver uses the sd_clock_hfclk_request() Softdevice function to start the clock, rather than trying to access the CLOCK peripheral directly (this is one of the peripherals reserved to the Softdevice).

Best regards,

Vidar

[moon.kim]

Thanks

This problem is solved.

However, when the device was in Sleep mode, nrf_drv_clock_hfclk_release() was performed and USB insert wake-up was not executed.

Is there any way to reduce the current while using the USB wake-up event?

[Vidar Berg]

Hi,

It shouldn't be neccessary to keep the clock running in sleep. Are you only receiving the USBDETECTED event if you don't release the HFXO (USBD power-up sequence)?

[moon.kim]

If so, is there a way to reduce the current consumption in sleep mode when using USBD?

[Vidar Berg]

What happens when you release the clock before entering sleep, does it not wake up again?