Functions and data related to the high-frequency clock. More...

#include <nrfcxx/clock.hpp>

Static Public Member Functions
static bool	hfxt_active ()
	Return `true` iff the high-frequency clock is being driven by a crystal oscillator. More...

static bool	hfxt_configure (int on)
	Enable, disable, or query the state of application request for the high-frequency crystal. More...

Static Public Attributes
constexpr static unsigned int	Frequency_Hz = 16'000'000
	The high-frequency clock always runs at nominal 16 MHz. More...

Static Protected Member Functions
static void	constlat_request (const periph::TIMER &timer, bool enable)
	Set or clear timer-based requests for constant latency wakeups. More...

Friends
class	periph::TIMER
	TIMER needs to request and release HFCLK constant latency.

Detailed Description

Functions and data related to the high-frequency clock.

The high-frequency clock is on when the system is in ON mode, but may be sourced from either crystal oscillator or an RC oscillator.

Note: This is a data type for visibility management only; all members are static and it is not possible to create or manipulate instances of the type.

Member Function Documentation

◆ constlat_request()

static void nrfcxx::clock::hfclk::constlat_request	(	const periph::TIMER &	timer,
		bool	enable
	)

staticprotected

Set or clear timer-based requests for constant latency wakeups.

See also: periph::TIMER::configure

Note: Although this supports nRF51 PAN 11 "HFCLK: Base current with HFCLK running is too high" by ensuring a running timer sets the power submode to force HFCLK active, it is independently useful to reduce latency when timer interrupts occur.

◆ hfxt_active()

static bool nrfcxx::clock::hfclk::hfxt_active ( )

inlinestatic

Return true iff the high-frequency clock is being driven by a crystal oscillator.

If false the clock uses the RC oscillator.

◆ hfxt_configure()

static bool nrfcxx::clock::hfclk::hfxt_configure ( int on )

static

Enable, disable, or query the state of application request for the high-frequency crystal.

Parameters

on	a positive value to enable the HFXT; zero to disable HFXT; a negative value to return the configured state without change.

Returns: true iff the configured state of the crystal is on.

Note: This controls whether the application requires the crystal as a source. hfxt_active() can be false when the crystal is configured enabled (e.g. while stabilizing), and can be true when the crystal is configured disabled (e.g. when calibrating a synthesized low-frequency clock).

Warning: On some nRF51 chips starting the HFXT may inhibit functional writes to nrf5::CLOCK->LFCLKSRC until the HFCLKSTARTED event is received. A reasonable workaround is to start the LFCLK first. See devzone for the anomaly report to Nordic.

Field Documentation

◆ Frequency_Hz

constexpr static unsigned int nrfcxx::clock::hfclk::Frequency_Hz = 16'000'000

staticconstexpr

The high-frequency clock always runs at nominal 16 MHz.

This is true for both nRF51 where system clock is at 16 MHz, and for nRF52 where system clock is at 64 MHz.

The documentation for this class was generated from the following file:

nrfcxx/clock.hpp

Static Public Member Functions

Static Public Attributes

Static Protected Member Functions