HFCLK control for serialization application.

[N.W]

Hi,

I'm developing a serialization system with nRF52832 and an application chip. My product is a power-sensitive.

The code of ble_connectivity in nRF5 SDK 17 calls nrf_drv_clock_init and nrf_drv_clock_hfclk_request.

1. Is it no problem for removing these calls? I want to know why the ble_connectivity sample code calls nrf_drv_clock_init and nrf_drv_clock_hfclk_request, even though some other sample applications do not call them.

2. Does nRF52832 automatically turn HFCLK on/off when RADIO event?　When advertising, is HFCLK turned on at the advertising RF signal sending, and off until next RF signal transmission for reducing the current?

[Einar Thorsrud]

Hi,

1. Is it no problem for removing these calls? I want to know why the ble_connectivity sample code calls nrf_drv_clock_init and nrf_drv_clock_hfclk_request, even though some other sample applications do not call them.

Are you using UART for serialization? If so, then I would keep this as having an accurate HF clock is important for reliable UART communication.

2. Does nRF52832 automatically turn HFCLK on/off when RADIO event?　When advertising, is HFCLK turned on at the advertising RF signal sending, and off until next RF signal transmission for reducing the current?

The SoftDevice will automatically use the HFXO whenever the radio is in use (as an accurate clock is needed), so that is not something you need to handle yourself.

[N.W]

Thank you for your answer. 

If SPI interface, can I remove nrf_drv_clock_init and nrf_drv_clock_hfclk_request call?

[Einar Thorsrud]

Hi,

Yes, SPI is synchronous, so using HFINT should not cause any problems in that case.

[N.W]

Thank you!