Overview

The MCUXpresso SDK provides a driver for the Real Time Clock (RTC) of MCUXpresso SDK devices.

Function groups

The RTC driver supports operating the module as a time counter.

Initialization and deinitialization

The function RTC_Init() initializes the RTC with specified configurations. The function RTC_GetDefaultConfig() gets the default configurations.

The function RTC_Deinit() disables the RTC timer and disables the module clock.

Get current counter

The function RTC_GetCounter() reads the current counter.

Set & Get Alarm

The function RTC_SetAlarm() sets the alarm counter. When the RTC counter reaches the value of alarm counter, the alarm interrupt may occur.

The function RTC_GetAlarm() reads the alarm counter.

Start & Stop timer

The function RTC_StartTimer() starts the RTC time counter.

The function RTC_StopTimer() stops the RTC time counter.

The function RTC_ResetTimer() resets the RTC time counter.

Status

Provides functions to get and clear the RTC status.

Interrupt

Provides functions to enable/disable RTC interrupts and get current enabled interrupts.

Typical use case

RTC tick example

Example to set the RTC current time and trigger an alarm. Refer to the driver examples codes located at <SDK_ROOT>/boards/<BOARD>/driver_examples/rtc

Data Structures
struct	rtc_config_t
	RTC config structure. More...

Enumerations
enum	rtc_interrupt_enable_t { kRTC_AlarmInterruptEnable = (1U << 15U), kRTC_TimeOverflowInterruptEnable = (1U << 16U), kRTC_AllInterruptsEnable = (3U << 15U) }
	List of RTC interrupts. More...

enum	rtc_status_flags_t { kRTC_CntRunFlag = (1U << 0U), kRTC_CntRstDoneFlag = (1U << 1U), kRTC_ResetFlag = (1U << 2U), kRTC_AlarmFlag = (1U << 15U), kRTC_TimeOverflowFlag = (1U << 16U), kRTC_AllNonClearableFlags = (7U << 0U), kRTC_AllClearableFlags = (3U << 15U) }
	List of RTC flags. More...

enum	rtc_clock_div_t { kRTC_ClockDiv1 = 0U, kRTC_ClockDiv2 = 1U, kRTC_ClockDiv4 = 2U, kRTC_ClockDiv8 = 3U, kRTC_ClockDiv16 = 4U, kRTC_ClockDiv32 = 5U, kRTC_ClockDiv64 = 6U, kRTC_ClockDiv128 = 7U, kRTC_ClockDiv256 = 8U, kRTC_ClockDiv512 = 9U, kRTC_ClockDiv1024 = 10U, kRTC_ClockDiv2048 = 11U, kRTC_ClockDiv4096 = 12U, kRTC_ClockDiv8192 = 13U, kRTC_ClockDiv16384 = 14U, kRTC_ClockDiv32768 = 15U }
	List of clock divider. More...

Driver version
#define	FSL_RTC_DRIVER_VERSION (MAKE_VERSION(2, 0, 0))
	Version 2.0.0.

Initialization and deinitialization
void	RTC_Init (RTC_Type base, const rtc_config_t config)
	Ungates the RTC clock and configures the peripheral for basic operation. More...

void	RTC_Deinit (RTC_Type *base)
	Stops the timer and gate the RTC clock. More...

void	RTC_GetDefaultConfig (rtc_config_t *config)
	Fills in the RTC config struct with the default settings. More...

Current Time & Alarm
uint32_t	RTC_GetCounter (RTC_Type *base)
	Gets current RTC counter value. More...

status_t	RTC_SetAlarm (RTC_Type *base, uint32_t alarmCnt)
	Sets the RTC alarm time. More...

uint32_t	RTC_GetAlarm (RTC_Type *base)
	Returns the RTC alarm counter value. More...

Interrupt Interface
void	RTC_EnableInterrupts (RTC_Type *base, uint32_t mask)
	Enables the selected RTC interrupts. More...

void	RTC_DisableInterrupts (RTC_Type *base, uint32_t mask)
	Disables the selected RTC interrupts. More...

uint32_t	RTC_GetEnabledInterrupts (RTC_Type *base)
	Gets the enabled RTC interrupts. More...

Status Interface
uint32_t	RTC_GetStatusFlags (RTC_Type *base)
	Gets the RTC status flags. More...

void	RTC_ClearStatusFlags (RTC_Type *base, uint32_t mask)
	Clears the RTC status flags. More...

Timer Start and Stop
void	RTC_StartTimer (RTC_Type *base)
	Starts the RTC time counter. More...

void	RTC_StopTimer (RTC_Type *base)
	Stops the RTC time counter. More...

void	RTC_ResetTimer (RTC_Type *base)
	Performs a counter reset on the RTC module. More...

Data Structure Documentation

struct rtc_config_t

This structure holds the configuration settings for the RTC peripheral. To initialize this structure to reasonable defaults, call the RTC_GetDefaultConfig() function and pass a pointer to your config structure instance.

The config struct can be made const so it resides in flash

Data Fields
bool	ignoreInRunning
	true: If the counter is already running, the configuration will be ignored. More...

bool	autoUpdateCntVal
	true: CNT_VAL is updated on every counter clock tick. More...

bool	stopCntInDebug
	true: In debug mode, stop the counters. More...

rtc_clock_div_t	clkDiv
	Counter clock divider. More...

uint32_t	cntUppVal
	If counter reaches this value, the counter will overflow to 0. More...

Field Documentation

bool rtc_config_t::ignoreInRunning

false: Counter will always be reset and the the configurations will always be set.

bool rtc_config_t::autoUpdateCntVal

false: CNT_VAL is not updated.

bool rtc_config_t::stopCntInDebug

false: In debug mode, counters are not affected.

rtc_clock_div_t rtc_config_t::clkDiv

uint32_t rtc_config_t::cntUppVal

Enumeration Type Documentation

enum rtc_interrupt_enable_t

Enumerator
kRTC_AlarmInterruptEnable	Alarm interrupt.
kRTC_TimeOverflowInterruptEnable	Time overflow interrupt.
kRTC_AllInterruptsEnable	All interrupts to enable.

enum rtc_status_flags_t

Enumerator
kRTC_CntRunFlag	Counter reset done flag.
kRTC_CntRstDoneFlag	Counter reset done flag.
kRTC_ResetFlag	Module reset flag.
kRTC_AlarmFlag	Alarm flag.
kRTC_TimeOverflowFlag	Time overflow flag.
kRTC_AllNonClearableFlags	All non-clearable flags.
kRTC_AllClearableFlags	All clearable flags.

enum rtc_clock_div_t

Enumerator
kRTC_ClockDiv1	Clock divider 1.
kRTC_ClockDiv2	Clock divider 2.
kRTC_ClockDiv4	Clock divider 4.
kRTC_ClockDiv8	Clock divider 8.
kRTC_ClockDiv16	Clock divider 16.
kRTC_ClockDiv32	Clock divider 32.
kRTC_ClockDiv64	Clock divider 64.
kRTC_ClockDiv128	Clock divider 128.
kRTC_ClockDiv256	Clock divider 256.
kRTC_ClockDiv512	Clock divider 512.
kRTC_ClockDiv1024	Clock divider 1024.
kRTC_ClockDiv2048	Clock divider 2048.
kRTC_ClockDiv4096	Clock divider 4096.
kRTC_ClockDiv8192	Clock divider 8192.
kRTC_ClockDiv16384	Clock divider 16384.
kRTC_ClockDiv32768	Clock divider 32768.

Function Documentation

void RTC_Init	(	RTC_Type *	base,
		const rtc_config_t *	config
	)

This function configures the RTC only if the counter is not running.

Note: This API should be called at the beginning of the application using the RTC driver.

Parameters

base	RTC peripheral base address
config	Pointer to the user's RTC configuration structure.

void RTC_Deinit ( RTC_Type * base )

Parameters

base	RTC peripheral base address

void RTC_GetDefaultConfig ( rtc_config_t * config )

The default values are as follows.

*    config->ignoreInRunning = true;
*    config->autoUpdateCntVal = true;
*    config->stopCntInDebug = true;
*    config->clkDiv = kRTC_ClockDiv32;
*    config->cntUppVal = 0xFFFFFFFFU;
* 

Parameters

config Pointer to the user's RTC configuration structure.

uint32_t RTC_GetCounter ( RTC_Type * base )

Parameters

base	RTC peripheral base address

Returns: counter value in RTC.

status_t RTC_SetAlarm	(	RTC_Type *	base,
		uint32_t	alarmCnt
	)

The function checks whether the specified alarm time is greater than the present time. If not, the function does not set the alarm and returns an error.

Parameters

base	RTC peripheral base address
alarmCnt	Counter value to trigger the alarm.

Returns: kStatus_Success: success in setting the RTC alarm kStatus_Fail: Error because the alarm time has already passed

uint32_t RTC_GetAlarm ( RTC_Type * base )

Parameters

base	RTC peripheral base address

Returns: Alarm counter value in RTC.

void RTC_EnableInterrupts	(	RTC_Type *	base,
		uint32_t	mask
	)

Parameters

base	RTC peripheral base address
mask	The interrupts to enable. This is a logical OR of members of the enumeration rtc_interrupt_enable_t

void RTC_DisableInterrupts	(	RTC_Type *	base,
		uint32_t	mask
	)

Parameters

base	RTC peripheral base address
mask	The interrupts to enable. This is a logical OR of members of the enumeration rtc_interrupt_enable_t

uint32_t RTC_GetEnabledInterrupts ( RTC_Type * base )

Parameters

base	RTC peripheral base address

Returns: The enabled interrupts. This is the logical OR of members of the enumeration rtc_interrupt_enable_t

uint32_t RTC_GetStatusFlags ( RTC_Type * base )

Parameters

base	RTC peripheral base address

Returns: The status flags. This is the logical OR of members of the enumeration rtc_status_flags_t

void RTC_ClearStatusFlags	(	RTC_Type *	base,
		uint32_t	mask
	)

Parameters

base	RTC peripheral base address
mask	The status flags to clear. This is a logical OR of members of the enumeration rtc_status_flags_t

void RTC_StartTimer ( RTC_Type * base )

Parameters

base	RTC peripheral base address

void RTC_StopTimer ( RTC_Type * base )

Parameters

base	RTC peripheral base address

void RTC_ResetTimer ( RTC_Type * base )

Parameters

base	RTC peripheral base address

Overview

Function groups

Initialization and deinitialization

Get current counter

Set & Get Alarm

Start & Stop timer

Status

Interrupt

Typical use case

RTC tick example

Data Structures

Enumerations

Driver version

Initialization and deinitialization

Current Time & Alarm

Interrupt Interface

Status Interface

Timer Start and Stop

Data Structure Documentation

Data Fields

Field Documentation

Enumeration Type Documentation

Function Documentation