Read Guidance

This document consists of sections titled with Driver Overview, Data Structures, Enumerations, Functions, etc., each with an overview list and detailed documentation. It is recommended to read the Driver Overview first for it includes a comprehensive description of the peripheral, driver and driver changes. Other sections give detailed information for APIs, enums, macros, etc., for your further reference.

Driver Overview
	PIT Peripheral and Driver Overview
	Content including 1) peripheral features, work logic and work method; 2) driver design logic and use method.

	The Driver Change Log
	The current PIT driver version is 2.2.0.

Data Structures
struct	pit_config_t
	PIT configuration structure. More...

Enumerations
enum	pit_prescaler_value_t { kPIT_PrescalerDivBy1 = 0x0U, kPIT_PrescalerDivBy2 = 0x1U, kPIT_PrescalerDivBy4 = 0x2U, kPIT_PrescalerDivBy8 = 0x3U, kPIT_PrescalerDivBy16 = 0x4U, kPIT_PrescalerDivBy32 = 0x5U, kPIT_PrescalerDivBy64 = 0x6U, kPIT_PrescalerDivBy128 = 0x7U, kPIT_PrescalerDivBy256 = 0x8U, kPIT_PrescalerDivBy512 = 0x9U, kPIT_PrescalerDivBy1024 = 0xAU, kPIT_PrescalerDivBy2048 = 0xBU, kPIT_PrescalerDivBy4096 = 0xCU, kPIT_PrescalerDivBy8192 = 0xDU, kPIT_PrescalerDivBy16384 = 0xEU, kPIT_PrescalerDivBy32768 = 0xFU }
	PIT clock prescaler values. More...

enum	_pit_status_flags { kPIT_Timer_RollOverFlag = PIT_CTRL_PRF_MASK }
	List of PIT status flags. More...

Driver version
#define	FSL_PIT_DRIVER_VERSION (MAKE_VERSION(2, 2, 0))
	PIT Driver Version.

Initialization and deinitialization Interfaces
void	PIT_Init (PIT_Type base, const pit_config_t psConfig)
	Ungates the PIT clock, configures the PIT features. More...

void	PIT_Deinit (PIT_Type *base)
	Gates the PIT clock and disables the PIT module. More...

void	PIT_GetDefaultConfig (pit_config_t *psConfig)
	Fill in the PIT config structure with the default settings. More...

PIT operation Interfaces

Sets the PIT clock prescaler.

Parameters

base	PIT peripheral base address
ePrescaler	Timer prescaler value

static void PIT_EnableSlaveMode (PIT_Type *base, bool bEnable)

Enable/Disable PIT slave mode. More...

static void PIT_SetTimerPrescaler (PIT_Type *base, pit_prescaler_value_t ePrescaler)

static void PIT_SetTimerPeriod (PIT_Type *base, uint16_t u16PeriodCount)

Sets the timer period in units of count. More...

static uint16_t PIT_GetCurrentTimerCount (PIT_Type *base)

Reads the current timer counting value. More...

static void PIT_StartTimer (PIT_Type *base)

Starts the timer counting. More...

static void PIT_StopTimer (PIT_Type *base)

Stops the timer counting. More...

Interrupt control Interfaces
static void	PIT_EnableInterrupt (PIT_Type *base)
	Enables the PIT interrupts. More...

static void	PIT_DisableInterrupt (PIT_Type *base)
	Disables the selected PIT interrupts. More...

PIT Status Flag Interfaces.
static uint32_t	PIT_GetStatusFlags (PIT_Type *base)
	Gets the PIT status flags. More...

static void	PIT_ClearStatusFlags (PIT_Type *base)
	Clears the PIT status flags. More...

Data Structure Documentation

struct pit_config_t

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

The configuration structure can be made constant so it resides in flash.

Data Fields
pit_prescaler_value_t	ePrescaler: 5
	Clock prescaler value.

bool	bEnableInterrupt: 1
	Enable PIT Roll-Over Interrupt.

bool	bEnableSlaveMode: 1
	Enable the PIT module in slave mode, in which mode the timer will be triggered by master PIT enable. More...

bool	bEnableTimer: 1
	PIT timer enable flag, which is false by default.

pit_count_clock_source_t	eClockSource
	Specify the PIT count clock source.

uint16_t	u16PeriodCount
	Timer period in clock cycles, Use macro definition MSEC_TO_COUNT to convert value in ms to count of ticks, the COP clock rate is source clock divide prescaler. More...

Field Documentation

bool pit_config_t::bEnableSlaveMode

uint16_t pit_config_t::u16PeriodCount

Enumeration Type Documentation

enum pit_prescaler_value_t

Enumerator
kPIT_PrescalerDivBy1	Clock divided by 1.
kPIT_PrescalerDivBy2	Clock divided by 2.
kPIT_PrescalerDivBy4	Clock divided by 4.
kPIT_PrescalerDivBy8	Clock divided by 8.
kPIT_PrescalerDivBy16	Clock divided by 16.
kPIT_PrescalerDivBy32	Clock divided by 32.
kPIT_PrescalerDivBy64	Clock divided by 64.
kPIT_PrescalerDivBy128	Clock divided by 128.
kPIT_PrescalerDivBy256	Clock divided by 256.
kPIT_PrescalerDivBy512	Clock divided by 512.
kPIT_PrescalerDivBy1024	Clock divided by 1024.
kPIT_PrescalerDivBy2048	Clock divided by 2048.
kPIT_PrescalerDivBy4096	Clock divided by 4096.
kPIT_PrescalerDivBy8192	Clock divided by 8192.
kPIT_PrescalerDivBy16384	Clock divided by 16384.
kPIT_PrescalerDivBy32768	Clock divided by 32768.

enum _pit_status_flags

Enumerator
kPIT_Timer_RollOverFlag	Timer roll over flag.

Function Documentation

void PIT_Init	(	PIT_Type *	base,
		const pit_config_t *	psConfig
	)

The configurations are:

Clock source selection for PIT module
Prescaler configuration to the input clock source
PIT period interval
PIT slave mode enable/disable
Interrupt enable/disable
PIT timer enable/disable

Note: This API should be called at the beginning of the application using the PIT driver and call PIT_StartTimer() API to start PIT timer.

Parameters

base	PIT peripheral base address
psConfig	Pointer to the user's PIT config structure

void PIT_Deinit ( PIT_Type * base )

Parameters

base	PIT peripheral base address

void PIT_GetDefaultConfig ( pit_config_t * psConfig )

This function initializes the PIT configuration structure to default values.

*    psConfig->ePrescaler = kPIT_PrescalerDivBy1;
*    psConfig->bEnableInterrupt = false;
*    psConfig->bEnableSlaveMode = false;
*    psConfig->bEnableTimer = false;
*    psConfig->eClockSource = kPIT_CountClockSource0;
*    psConfig->u16PeriodCount = 0xFFFFU;
* 

Parameters

psConfig Pointer to user's PIT config structure.

static void PIT_EnableSlaveMode	(	PIT_Type *	base,
		bool	bEnable
	)

inlinestatic

Parameters

base	PIT peripheral base address
bEnable	enable/disable slave mode

static void PIT_SetTimerPeriod	(	PIT_Type *	base,
		uint16_t	u16PeriodCount
	)

inlinestatic

Timers begin counting from 0 until it reaches the value set by this function, then it generates an interrupt and counter resumes counting from 0 again.

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

Parameters

base	PIT peripheral base address
count	Timer period in units of ticks, use macro definition MSEC_TO_COUNT to convert value in ms to count of ticks, the PIT clock rate is source clock divide prescaler.

static uint16_t PIT_GetCurrentTimerCount ( PIT_Type * base )

inlinestatic

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

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

Parameters

base	PIT peripheral base address

Returns: Current timer counting value in ticks, use macro definition COUNT_TO_MSEC to convert value in ticks to count of millisecond, the PIT clock rate is source clock divide prescaler.

static void PIT_StartTimer ( PIT_Type * base )

inlinestatic

After calling this function, timers load period value, count down to 0 and then load the respective start value again. Each time a timer reaches 0, it generates a trigger pulse and sets the timeout interrupt flag.

Parameters

base	PIT peripheral base address

static void PIT_StopTimer ( PIT_Type * base )

inlinestatic

This function stops timer counting, and the counter remains at or returns to a 0 value.

Parameters

base	PIT peripheral base address

static void PIT_EnableInterrupt ( PIT_Type * base )

inlinestatic

Parameters

base	PIT peripheral base address

static void PIT_DisableInterrupt ( PIT_Type * base )

inlinestatic

Parameters

base	PIT peripheral base address

static uint32_t PIT_GetStatusFlags ( PIT_Type * base )

inlinestatic

Parameters

base	PIT peripheral base address

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

static void PIT_ClearStatusFlags ( PIT_Type * base )

inlinestatic

Parameters

base	PIT peripheral base address

Read Guidance

Driver Overview

Data Structures

Enumerations

Driver version

Initialization and deinitialization Interfaces

PIT operation Interfaces

Interrupt control Interfaces

PIT Status Flag Interfaces.

Data Structure Documentation

Data Fields

Field Documentation

Enumeration Type Documentation

Function Documentation