RTC driver

group nrfx_rtc

Real Timer Counter (RTC) peripheral driver.

Defines

NRFX_RTC_US_TO_TICKS(us, freq)

Macro for converting microseconds into ticks.

NRFX_RTC_INSTANCE(id)

Macro for creating an RTC driver instance.

NRFX_RTC_DEFAULT_CONFIG

RTC driver default configuration.

This configuration sets up RTC with the following options:

  • frequency 32.768 kHz

  • maximum latency 2000 us

  • reliability checks disabled

NRFX_RTC_INST_HANDLER_GET(idx)

Macro returning RTC interrupt handler.

param[in] idx RTC index.

Returns:

Interrupt handler.

Typedefs

typedef void (*nrfx_rtc_handler_t)(nrfx_rtc_int_type_t int_type)

RTC driver instance handler type.

Enums

enum nrfx_rtc_int_type_t

RTC driver interrupt types.

Values:

enumerator NRFX_RTC_INT_COMPARE0

Interrupt from COMPARE0 event.

enumerator NRFX_RTC_INT_COMPARE1

Interrupt from COMPARE1 event.

enumerator NRFX_RTC_INT_COMPARE2

Interrupt from COMPARE2 event.

enumerator NRFX_RTC_INT_COMPARE3

Interrupt from COMPARE3 event.

enumerator NRFX_RTC_INT_TICK

Interrupt from TICK event.

enumerator NRFX_RTC_INT_OVERFLOW

Interrupt from OVERFLOW event.

Functions

nrfx_err_t nrfx_rtc_init(nrfx_rtc_t const *p_instance, nrfx_rtc_config_t const *p_config, nrfx_rtc_handler_t handler)

Function for initializing the RTC driver instance.

After initialization, the instance is in power off state.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

  • p_config – [in] Pointer to the structure with the initial configuration.

  • handler – [in] Event handler provided by the user. Must not be NULL.

Return values:

  • NRFX_SUCCESS – Successfully initialized.

  • NRFX_ERROR_INVALID_STATE – The instance is already initialized.

void nrfx_rtc_uninit(nrfx_rtc_t const *p_instance)

Function for uninitializing the RTC driver instance.

After uninitialization, the instance is in idle state. The hardware should return to the state before initialization.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

void nrfx_rtc_enable(nrfx_rtc_t const *p_instance)

Function for enabling the RTC driver instance.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

void nrfx_rtc_disable(nrfx_rtc_t const *p_instance)

Function for disabling the RTC driver instance.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

nrfx_err_t nrfx_rtc_cc_set(nrfx_rtc_t const *p_instance, uint32_t channel, uint32_t val, bool enable_irq)

Function for setting a compare channel.

The function powers on the instance if the instance was in power off state.

The driver is not entering a critical section when configuring RTC, which means that it can be preempted for a certain amount of time. When the driver was preempted and the value to be set is short in time, there is a risk that the driver sets a compare value that is behind. In this case, if the reliable mode is enabled for the specified instance, the risk is handled. However, to detect if the requested value is behind, this mode makes the following assumptions:

  • The maximum preemption time in ticks (8-bit value) is known and is less than 7.7 ms (for prescaler = 0, RTC frequency 32 kHz).

  • The requested absolute compare value is not bigger than (0x00FFFFFF)-tick_latency. It is the user’s responsibility to ensure this.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

  • channel – [in] One of the channels of the instance.

  • val – [in] Absolute value to be set in the compare register.

  • enable_irq – [in] True to enable the interrupt. False to disable the interrupt.

Return values:

  • NRFX_SUCCESS – The procedure is successful.

  • NRFX_ERROR_TIMEOUT – The compare is not set because the request value is behind the current counter value. This error can only be reported if the reliable mode is enabled.

nrfx_err_t nrfx_rtc_cc_disable(nrfx_rtc_t const *p_instance, uint32_t channel)

Function for disabling a channel.

This function disables channel events and channel interrupts.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

  • channel – [in] One of the channels of the instance.

Return values:

  • NRFX_SUCCESS – The procedure is successful.

  • NRFX_ERROR_TIMEOUT – Interrupt is pending on the requested channel.

void nrfx_rtc_tick_enable(nrfx_rtc_t const *p_instance, bool enable_irq)

Function for enabling the TICK event.

This function enables the tick event and optionally the interrupt.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

  • enable_irq – [in] True to enable the interrupt. False to disable the interrupt.

void nrfx_rtc_tick_disable(nrfx_rtc_t const *p_instance)

Function for disabling the TICK event.

This function disables the TICK event and interrupt.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

void nrfx_rtc_overflow_enable(nrfx_rtc_t const *p_instance, bool enable_irq)

Function for enabling overflow.

This function enables the overflow event and optionally the interrupt.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

  • enable_irq – [in] True to enable the interrupt. False to disable the interrupt.

void nrfx_rtc_overflow_disable(nrfx_rtc_t const *p_instance)

Function for disabling overflow.

This function disables the overflow event and interrupt.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

uint32_t nrfx_rtc_max_ticks_get(nrfx_rtc_t const *p_instance)

Function for getting the maximum relative tick value that can be set in the compare channel.

When a stack (for example SoftDevice) is used and it occupies high priority interrupts, the application code can be interrupted at any moment for a certain period of time. If the reliable mode is enabled, the provided maximum latency is taken into account and the return value is smaller than the RTC counter resolution. If the reliable mode is disabled, the return value equals the counter resolution.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

Returns:

Maximum ticks value.

NRFX_STATIC_INLINE void nrfx_rtc_int_disable(nrfx_rtc_t const *p_instance, uint32_t *p_mask)

Function for disabling all instance interrupts.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

  • p_mask – [in] Pointer to the location where the mask is filled.

NRFX_STATIC_INLINE void nrfx_rtc_int_enable(nrfx_rtc_t const *p_instance, uint32_t mask)

Function for enabling instance interrupts.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

  • mask – [in] Mask of interrupts to enable.

NRFX_STATIC_INLINE uint32_t nrfx_rtc_counter_get(nrfx_rtc_t const *p_instance)

Function for retrieving the current counter value.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

Returns:

Counter value.

NRFX_STATIC_INLINE void nrfx_rtc_counter_clear(nrfx_rtc_t const *p_instance)

Function for clearing the counter value.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

NRFX_STATIC_INLINE uint32_t nrfx_rtc_task_address_get(nrfx_rtc_t const *p_instance, nrf_rtc_task_t task)

Function for returning a requested task address for the RTC driver instance.

The task address can be used by the PPI module.

Parameters:

  • p_instance – [in] Pointer to the instance.

  • task – [in] One of the peripheral tasks.

Returns:

Address of task register.

NRFX_STATIC_INLINE uint32_t nrfx_rtc_event_address_get(nrfx_rtc_t const *p_instance, nrf_rtc_event_t event)

Function for returning a requested event address for the RTC driver instance.

The event address can be used by the PPI module.

Parameters:

  • p_instance – [in] Pointer to the driver instance structure.

  • event – [in] One of the peripheral events.

Returns:

Address of event register.

struct nrfx_rtc_t
#include <nrfx_rtc.h>

RTC driver instance structure.

Public Members

NRF_RTC_Type *p_reg

Pointer to instance register set.

IRQn_Type irq

Instance IRQ ID.

uint8_t instance_id

Index of the driver instance. For internal use only.

uint8_t cc_channel_count

Number of capture/compare channels.

struct nrfx_rtc_config_t
#include <nrfx_rtc.h>

RTC driver instance configuration structure.

Public Members

uint16_t prescaler

Prescaler.

uint8_t interrupt_priority

Interrupt priority.

uint8_t tick_latency

Maximum length of the interrupt handler in ticks (maximum 7.7 ms).

bool reliable

Reliable mode flag.