EWM: External Watchdog Monitor Driver

Overview

The MCUXpresso SDK provides a peripheral driver for the External Watchdog (EWM) Driver module of MCUXpresso SDK devices.

Typical use case

Refer to the driver examples codes located at <SDK_ROOT>/boards/<BOARD>/driver_examples/ewm

Data Structures
struct	ewm_config_t
	Data structure for EWM configuration. More...

Enumerations
enum	ewm_lpo_clock_source_t {   kEWM_LpoClockSource0 = 0U,   kEWM_LpoClockSource1 = 1U,   kEWM_LpoClockSource2 = 2U,   kEWM_LpoClockSource3 = 3U }
	Describes EWM clock source. More...
enum	_ewm_interrupt_enable_t { kEWM_InterruptEnable = EWM_CTRL_INTEN_MASK }
	EWM interrupt configuration structure with default settings all disabled. More...
enum	_ewm_status_flags_t { kEWM_RunningFlag = EWM_CTRL_EWMEN_MASK }
	EWM status flags. More...

Driver version
#define	FSL_EWM_DRIVER_VERSION   (MAKE_VERSION(2, 0, 2))
	EWM driver version 2.0.2. More...

EWM initialization and de-initialization
void	EWM_Init (EWM_Type *base, const ewm_config_t *config)
	Initializes the EWM peripheral. More...
void	EWM_Deinit (EWM_Type *base)
	Deinitializes the EWM peripheral. More...
void	EWM_GetDefaultConfig (ewm_config_t *config)
	Initializes the EWM configuration structure. More...

EWM functional Operation
static void	EWM_EnableInterrupts (EWM_Type *base, uint32_t mask)
	Enables the EWM interrupt. More...
static void	EWM_DisableInterrupts (EWM_Type *base, uint32_t mask)
	Disables the EWM interrupt. More...
static uint32_t	EWM_GetStatusFlags (EWM_Type *base)
	Gets all status flags. More...
void	EWM_Refresh (EWM_Type *base)
	Services the EWM. More...

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Data Structure Documentation

struct ewm_config_t

This structure is used to configure the EWM.

Data Fields
bool	enableEwm
	Enable EWM module.
bool	enableEwmInput
	Enable EWM_in input.
bool	setInputAssertLogic
	EWM_in signal assertion state.
bool	enableInterrupt
	Enable EWM interrupt.
ewm_lpo_clock_source_t	clockSource
	Clock source select.
uint8_t	prescaler
	Clock prescaler value.
uint8_t	compareLowValue
	Compare low-register value.
uint8_t	compareHighValue
	Compare high-register value.

Macro Definition Documentation

#define FSL_EWM_DRIVER_VERSION   (MAKE_VERSION(2, 0, 2))

Enumeration Type Documentation

enum ewm_lpo_clock_source_t

Enumerator
kEWM_LpoClockSource0	EWM clock sourced from lpo_clk[0].
kEWM_LpoClockSource1	EWM clock sourced from lpo_clk[1].
kEWM_LpoClockSource2	EWM clock sourced from lpo_clk[2].
kEWM_LpoClockSource3	EWM clock sourced from lpo_clk[3].

enum _ewm_interrupt_enable_t

This structure contains the settings for all of EWM interrupt configurations.

Enumerator
kEWM_InterruptEnable	Enable the EWM to generate an interrupt.

enum _ewm_status_flags_t

This structure contains the constants for the EWM status flags for use in the EWM functions.

Enumerator
kEWM_RunningFlag	Running flag, set when EWM is enabled.

Function Documentation

void EWM_Init	(	EWM_Type *	base,
		const ewm_config_t *	config
	)

This function is used to initialize the EWM. After calling, the EWM runs immediately according to the configuration. Note that, except for the interrupt enable control bit, other control bits and registers are write once after a CPU reset. Modifying them more than once generates a bus transfer error.

This is an example.

*   ewm_config_t config;
*   EWM_GetDefaultConfig(&config);
*   config.compareHighValue = 0xAAU;
*   EWM_Init(ewm_base,&config);
* 

Parameters

base	EWM peripheral base address
config	The configuration of the EWM

void EWM_Deinit

(

EWM_Type *

base

)

This function is used to shut down the EWM.

Parameters

base	EWM peripheral base address

void EWM_GetDefaultConfig

(

ewm_config_t *

config

)

This function initializes the EWM configuration structure to default values. The default values are as follows.

*   ewmConfig->enableEwm = true;
*   ewmConfig->enableEwmInput = false;
*   ewmConfig->setInputAssertLogic = false;
*   ewmConfig->enableInterrupt = false;
*   ewmConfig->ewm_lpo_clock_source_t = kEWM_LpoClockSource0;
*   ewmConfig->prescaler = 0;
*   ewmConfig->compareLowValue = 0;
*   ewmConfig->compareHighValue = 0xFEU;
* 

Parameters

config

Pointer to the EWM configuration structure.

See Also

ewm_config_t

static void EWM_EnableInterrupts ( EWM_Type *  base, uint32_t  mask  )

inlinestatic

This function enables the EWM interrupt.

Parameters

base	EWM peripheral base address
mask	The interrupts to enable The parameter can be combination of the following source if defined kEWM_InterruptEnable

static void EWM_DisableInterrupts ( EWM_Type *  base, uint32_t  mask  )

inlinestatic

This function enables the EWM interrupt.

Parameters

base	EWM peripheral base address
mask	The interrupts to disable The parameter can be combination of the following source if defined kEWM_InterruptEnable

static uint32_t EWM_GetStatusFlags ( EWM_Type *  base )

inlinestatic

This function gets all status flags.

This is an example for getting the running flag.

*   uint32_t status;
*   status = EWM_GetStatusFlags(ewm_base) & kEWM_RunningFlag;
* 

Parameters

base	EWM peripheral base address

Returns

State of the status flag: asserted (true) or not-asserted (false).

See Also

_ewm_status_flags_t

• True: a related status flag has been set.
• False: a related status flag is not set.

void EWM_Refresh

(

EWM_Type *

base

)

This function resets the EWM counter to zero.

Parameters

base	EWM peripheral base address