nrf5340 external lfclk test

RE: nrf5340 external lfclk test

ketiljo — Tue, 06 Apr 2021 12:30:18 GMT

The external HF clock is only needed by the radio, the CPU runs on a internal RC oscillator unless you change the config The HF and LF clock sources are used for different things. Typically, only the RTC and WDT are clocked from the LF clock. https://infocenter.nordicsemi.com/topic/ps_nrf5340/chapters/clock/doc/clock.html

Timers are clocked from the HF clock, so either the RC or the XO depending on the config.

RE: nrf5340 external lfclk test

Август — Tue, 06 Apr 2021 10:03:33 GMT

Hi ketiljo,

Thanks for your quick reply.

We want to make sure only external lfclk so remmove the HF clock.

We use the following two projects to test.

app:v1.5.0\nrf\samples\nrf5340\empty_app_core

net:v1.5.0\nrf\samples\peripheral\radio_test

I set up a thread to control the led.

How to ensure that only low-speed crystals are working on boards with high-speed crystals?

Thank you

RE: nrf5340 external lfclk test

ketiljo — Tue, 06 Apr 2021 09:45:26 GMT

[quote user=""]board: nrf5340dk without hfclk[/quote]

Is this a typo? It won't work well without the HF clock.

The external LF clock must be a 32.768 kHz clock source. See the product specification for more: https://infocenter.nordicsemi.com/topic/ps_nrf5340/chapters/oscillators/doc/oscillators.html#concept_32k_xosc