Overview

The MCUXpresso SDK provides a driver for the Multi-Rate Timer (MRT) of MCUXpresso SDK devices.

Function groups

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

Initialization and deinitialization

The function MRT_Init() initializes the MRT with specified configurations. The function MRT_GetDefaultConfig() gets the default configurations. The initialization function configures the MRT operating mode.

The function MRT_Deinit() stops the MRT timers and disables the module clock.

Timer period Operations

The function MRT_UpdateTimerPeriod() is used to update the timer period in units of count. The new value will be immediately loaded or will be loaded at the end of the current time interval.

The function MRT_GetCurrentTimerCount() reads the current timer counting value. This function returns the real-time timer counting value, in a range from 0 to a timer period.

The timer period operation functions takes the count value in ticks. User can call the utility macros provided in fsl_common.h to convert to microseconds or milliseconds

Start and Stop timer operations

The function MRT_StartTimer() starts the timer counting. After calling this function, the timer loads the period value, counts down to 0 and depending on the timer mode it will either load the respective start value again or stop. When the timer reaches 0, it generates a trigger pulse and sets the timeout interrupt flag.

The function MRT_StopTimer() stops the timer counting.

Get and release channel

These functions can be used to reserve and release a channel. The function MRT_GetIdleChannel() finds the available channel. This function returns the lowest available channel number. The function MRT_ReleaseChannel() release the channel when the timer is using the multi-task mode. In multi-task mode, the INUSE flags allow more control over when MRT channels are released for further use.

Status

Provides functions to get and clear the PIT status.

Interrupt

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

Typical use case

MRT tick example

Updates the MRT period and toggles an LED periodically. Refer to the driver examples codes located at <SDK_ROOT>/boards/<BOARD>/driver_examples/mrt

Files
file	fsl_mrt.h

Data Structures
struct	mrt_config_t
	MRT configuration structure. More...

Enumerations
enum	mrt_chnl_t { kMRT_Channel_0 = 0U, kMRT_Channel_1, kMRT_Channel_2, kMRT_Channel_3 }
	List of MRT channels. More...

enum	mrt_timer_mode_t { kMRT_RepeatMode = (0 << MRT_CHANNEL_CTRL_MODE_SHIFT), kMRT_OneShotMode = (1 << MRT_CHANNEL_CTRL_MODE_SHIFT), kMRT_OneShotStallMode = (2 << MRT_CHANNEL_CTRL_MODE_SHIFT) }
	List of MRT timer modes. More...

enum	mrt_interrupt_enable_t { kMRT_TimerInterruptEnable = MRT_CHANNEL_CTRL_INTEN_MASK }
	List of MRT interrupts. More...

enum	mrt_status_flags_t { kMRT_TimerInterruptFlag = MRT_CHANNEL_STAT_INTFLAG_MASK, kMRT_TimerRunFlag = MRT_CHANNEL_STAT_RUN_MASK }
	List of MRT status flags. More...

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

Initialization and deinitialization
void	MRT_Init (MRT_Type base, const mrt_config_t config)
	Ungates the MRT clock and configures the peripheral for basic operation. More...

void	MRT_Deinit (MRT_Type *base)
	Gate the MRT clock. More...

static void	MRT_GetDefaultConfig (mrt_config_t *config)
	Fill in the MRT config struct with the default settings. More...

static void	MRT_SetupChannelMode (MRT_Type *base, mrt_chnl_t channel, const mrt_timer_mode_t mode)
	Sets up an MRT channel mode. More...

Interrupt Interface
static void	MRT_EnableInterrupts (MRT_Type *base, mrt_chnl_t channel, uint32_t mask)
	Enables the MRT interrupt. More...

static void	MRT_DisableInterrupts (MRT_Type *base, mrt_chnl_t channel, uint32_t mask)
	Disables the selected MRT interrupt. More...

static uint32_t	MRT_GetEnabledInterrupts (MRT_Type *base, mrt_chnl_t channel)
	Gets the enabled MRT interrupts. More...

Status Interface
static uint32_t	MRT_GetStatusFlags (MRT_Type *base, mrt_chnl_t channel)
	Gets the MRT status flags. More...

static void	MRT_ClearStatusFlags (MRT_Type *base, mrt_chnl_t channel, uint32_t mask)
	Clears the MRT status flags. More...

Read and Write the timer period
void	MRT_UpdateTimerPeriod (MRT_Type *base, mrt_chnl_t channel, uint32_t count, bool immediateLoad)
	Used to update the timer period in units of count. More...

static uint32_t	MRT_GetCurrentTimerCount (MRT_Type *base, mrt_chnl_t channel)
	Reads the current timer counting value. More...

Timer Start and Stop
static void	MRT_StartTimer (MRT_Type *base, mrt_chnl_t channel, uint32_t count)
	Starts the timer counting. More...

static void	MRT_StopTimer (MRT_Type *base, mrt_chnl_t channel)
	Stops the timer counting. More...

Get & release channel
static uint32_t	MRT_GetIdleChannel (MRT_Type *base)
	Find the available channel. More...

static void	MRT_ReleaseChannel (MRT_Type *base, mrt_chnl_t channel)
	Release the channel when the timer is using the multi-task mode. More...

Data Structure Documentation

struct mrt_config_t

This structure holds the configuration settings for the MRT peripheral. To initialize this structure to reasonable defaults, call the MRT_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	enableMultiTask
	true: Timers run in multi-task mode; false: Timers run in hardware status mode

Enumeration Type Documentation

enum mrt_chnl_t

Enumerator
kMRT_Channel_0	MRT channel number 0.
kMRT_Channel_1	MRT channel number 1.
kMRT_Channel_2	MRT channel number 2.
kMRT_Channel_3	MRT channel number 3.

enum mrt_timer_mode_t

Enumerator
kMRT_RepeatMode	Repeat Interrupt mode.
kMRT_OneShotMode	One-shot Interrupt mode.
kMRT_OneShotStallMode	One-shot stall mode.

enum mrt_interrupt_enable_t

Enumerator
kMRT_TimerInterruptEnable	Timer interrupt enable.

enum mrt_status_flags_t

Enumerator
kMRT_TimerInterruptFlag	Timer interrupt flag.
kMRT_TimerRunFlag	Indicates state of the timer.

Function Documentation

void MRT_Init	(	MRT_Type *	base,
		const mrt_config_t *	config
	)

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

Parameters

base	Multi-Rate timer peripheral base address
config	Pointer to user's MRT config structure

void MRT_Deinit ( MRT_Type * base )

Parameters

base	Multi-Rate timer peripheral base address

static void MRT_GetDefaultConfig ( mrt_config_t * config )

inlinestatic

The default values are:

* config->enableMultiTask = false;

*

Parameters

config Pointer to user's MRT config structure.

static void MRT_SetupChannelMode	(	MRT_Type *	base,
		mrt_chnl_t	channel,
		const mrt_timer_mode_t	mode
	)

inlinestatic

Parameters

base	Multi-Rate timer peripheral base address
channel	Channel that is being configured.
mode	Timer mode to use for the channel.

static void MRT_EnableInterrupts	(	MRT_Type *	base,
		mrt_chnl_t	channel,
		uint32_t	mask
	)

inlinestatic

Parameters

base	Multi-Rate timer peripheral base address
channel	Timer channel number
mask	The interrupts to enable. This is a logical OR of members of the enumeration mrt_interrupt_enable_t

static void MRT_DisableInterrupts	(	MRT_Type *	base,
		mrt_chnl_t	channel,
		uint32_t	mask
	)

inlinestatic

Parameters

base	Multi-Rate timer peripheral base address
channel	Timer channel number
mask	The interrupts to disable. This is a logical OR of members of the enumeration mrt_interrupt_enable_t

static uint32_t MRT_GetEnabledInterrupts	(	MRT_Type *	base,
		mrt_chnl_t	channel
	)

inlinestatic

Parameters

base	Multi-Rate timer peripheral base address
channel	Timer channel number

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

static uint32_t MRT_GetStatusFlags	(	MRT_Type *	base,
		mrt_chnl_t	channel
	)

inlinestatic

Parameters

base	Multi-Rate timer peripheral base address
channel	Timer channel number

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

static void MRT_ClearStatusFlags	(	MRT_Type *	base,
		mrt_chnl_t	channel,
		uint32_t	mask
	)

inlinestatic

Parameters

base	Multi-Rate timer peripheral base address
channel	Timer channel number
mask	The status flags to clear. This is a logical OR of members of the enumeration mrt_status_flags_t

void MRT_UpdateTimerPeriod	(	MRT_Type *	base,
		mrt_chnl_t	channel,
		uint32_t	count,
		bool	immediateLoad
	)

The new value will be immediately loaded or will be loaded at the end of the current time interval. For one-shot interrupt mode the new value will be immediately loaded.

Note: User can call the utility macros provided in fsl_common.h to convert to ticks

Parameters

base	Multi-Rate timer peripheral base address
channel	Timer channel number
count	Timer period in units of ticks
immediateLoad	true: Load the new value immediately into the TIMER register; false: Load the new value at the end of current timer interval

static uint32_t MRT_GetCurrentTimerCount	(	MRT_Type *	base,
		mrt_chnl_t	channel
	)

inlinestatic

This function returns the real-time timer counting value, in a range from 0 to a timer period.

Note: User can call the utility macros provided in fsl_common.h to convert ticks to usec or msec

Parameters

base	Multi-Rate timer peripheral base address
channel	Timer channel number

Returns: Current timer counting value in ticks

static void MRT_StartTimer	(	MRT_Type *	base,
		mrt_chnl_t	channel,
		uint32_t	count
	)

inlinestatic

After calling this function, timers load period value, counts down to 0 and depending on the timer mode it will either load the respective start value again or stop.

Note: User can call the utility macros provided in fsl_common.h to convert to ticks

Parameters

base	Multi-Rate timer peripheral base address
channel	Timer channel number.
count	Timer period in units of ticks

static void MRT_StopTimer	(	MRT_Type *	base,
		mrt_chnl_t	channel
	)

inlinestatic

This function stops the timer from counting.

Parameters

base	Multi-Rate timer peripheral base address
channel	Timer channel number.

static uint32_t MRT_GetIdleChannel ( MRT_Type * base )

inlinestatic

This function returns the lowest available channel number.

Parameters

base	Multi-Rate timer peripheral base address

static void MRT_ReleaseChannel	(	MRT_Type *	base,
		mrt_chnl_t	channel
	)

inlinestatic

In multi-task mode, the INUSE flags allow more control over when MRT channels are released for further use. The user can hold on to a channel acquired by calling MRT_GetIdleChannel() for as long as it is needed and release it by calling this function. This removes the need to ask for an available channel for every use.

Parameters

base	Multi-Rate timer peripheral base address
channel	Timer channel number.

Overview

Function groups

Initialization and deinitialization

Timer period Operations

Start and Stop timer operations

Get and release channel

Status

Interrupt

Typical use case

MRT tick example

Files

Data Structures

Enumerations

Driver version

Initialization and deinitialization

Interrupt Interface

Status Interface

Read and Write the timer period

Timer Start and Stop

Get & release channel

Data Structure Documentation

Data Fields

Enumeration Type Documentation

Function Documentation