EWM: External Watchdog Monitor Driver

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
	EWM Peripheral and Driver Overview
	Content including 1) peripheral features, work logic and work method; 2) driver design logic and use method; 3) typical use case.
	The Driver Change Log
	The current EWM driver version is 2.0.0.

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

Enumerations
enum	ewm_input_assert_state_t {   kEWM_EwmInZeroAssert = 0U,   kEWM_EwmInOneAssert = 1U }

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

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

EWM functional Operation
static void	EWM_EnableInterrupt (EWM_Type *base)
	Enables the EWM interrupt. More...
static void	EWM_DisableInterrupt (EWM_Type *base)
	Disables the EWM interrupt. More...
void	EWM_Refresh (EWM_Type *base)
	Services the EWM. More...

---

Data Structure Documentation

struct ewm_config_t

This structure is used to configure the EWM.

Data Fields
uint8_t	bEnableEWM: 1
	Enable EWM module.
uint8_t	bEnableEWMInput: 1
	Enable EWM_in input.
uint8_t	bEnableInterrupt: 1
	Enable EWM interrupt.
ewm_input_assert_state_t	eInputAssertState: 1
	EWM_in signal assertion state select.
ewm_lpo_clock_source_t	eClockSource: 2
	Clock source select.
uint8_t	u8ClockDivder
	EWM counter clock is clockSource/(clockDivder+1)
uint8_t	u8CompareLowValue
	Compare low-register value.
uint8_t	u8CompareHighValue
	Compare high-register value, maximum setting is 0xFE.

Enumeration Type Documentation

enum ewm_input_assert_state_t

Enumerator
kEWM_EwmInZeroAssert	EWM-in assert with low-voltage logic.
kEWM_EwmInOneAssert	EWM-in assert with high-voltage logic.

Function Documentation

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

This function is used to initialize the EWM. After calling, the EWM runs immediately according to the configuration.

Note

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

Parameters

base	EWM peripheral base address
psConfig	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 *

psConfig

)

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

*   ewmConfig->bEnableEWM = true;
*   ewmConfig->bEnableEWMInput = false;
*   ewmConfig->eInputAssertState = kEWM_EwmInZeroAssert;
*   ewmConfig->bEnableInterrupt = false;
*   ewmConfig->eClockSource = kEWM_LpoClockSource0;
*   ewmConfig->u8ClockDivder = 0;
*   ewmConfig->u8CompareLowValue = 0;
*   ewmConfig->u8CompareHighValue = 0xFEU;
* 

Parameters

psConfig

Pointer to the EWM configuration structure.

See Also

ewm_config_t

static void EWM_EnableInterrupt ( EWM_Type *  base )

inlinestatic

This function enables the EWM interrupt.

Parameters

base	EWM peripheral base address

static void EWM_DisableInterrupt ( EWM_Type *  base )

inlinestatic

This function disables the EWM interrupt.

Parameters

base	EWM peripheral base address

void EWM_Refresh

(

EWM_Type *

base

)

This function resets the EWM counter to zero.

Parameters

base	EWM peripheral base address