WDT: Watchdog Timer Driver

Overview

Peripheral features and how this peripheral works

The Watchdog Timer (WDT) regains control in case of system failure (due to a software error) to increase application reliability. The WDT can generate a reset or an interrupt when the counter reaches a given timeout value.

Features

• clock source from APB clock
• 32-bit down counter with the minimal timeout value of 65536
• Configurable reset or interrupt generation with the given timeout value
• Supports 8 bytes of reset pulse length configuration

How this peripheral works

1. Configure the WDT features properly, enable WDT
2. Service periodically to prevent reset event

How this driver is designed to make this peripheral works.

The wdt driver provides a structure wdt_config_t which contains all the programmable features of WDT. The WDT_Init() function takes the argument of structure pointer to wdt_config_t and configures the WDT features, then enable WDT. For the most simple user scenarios, only need to provide WDT service function to feed the WDT timer to avoid reset. But considering user may have some enhanced situation which needs to re-configure the features, such as to re-install timeout value, enable/disable interrupt functionality of WDT, several function groups are designed as below:

• Initialization Interfaces The APIs in the functional group is used to initialize WDT module.
• WDT operation Interfaces The APIs in this functional group allows user to re-configure the WDT features and service WDT timer.
• Interrupt control Interfaces The APIs in this functional group can be used to enable/disable WDT interrupt
• Status get/clear Interfaces The APIs in this functional group can be used to get/clear WDT interrupt status

How to use this driver

• Sets the WDT features by invoking WDT_Init()
  • Defines the variable in type of wdt_config_t. This variable takes 2 Bytes space.
  • [Optional] Invokes WDT_GetDefaultConfig() function with the pointer of variable which is type of wdt_config_t to get the default options.
  • Sets the member of the variable which is in type of wdt_config_t.
  • Invoke WDT_Init to set the WDT features and enable WDT.
• Call to WDT service API to feed WDT periodically by invoking WDT_Refresh()

Data Structures
struct	wdt_config_t
	structure for WDT module initialization configuration. More...

Enumerations
enum	wdt_timeout_response_mode_t {   kWDT_ModeTimeoutReset = 0,   kWDT_ModeTimeoutInterrupt = 1 }
	enumeration for wdt timeout response mode select. More...
enum	wdt_reset_width_t {   kWDT_ResetPulseLen2 = 0,   kWDT_ResetPulseLen4 = 1,   kWDT_ResetPulseLen8 = 2,   kWDT_ResetPulseLen16 = 3,   kWDT_ResetPulseLen32 = 4,   kWDT_ResetPulseLen64 = 5,   kWDT_ResetPulseLen128 = 6,   kWDT_ResetPulseLen256 = 7 }
	enumeration for wdt reset assert width select. More...
enum	wdt_timeout_value_t {   kWDT_TimeoutVal2ToThePowerOf16 = 0,   kWDT_TimeoutVal2ToThePowerOf17 = 1,   kWDT_TimeoutVal2ToThePowerOf18 = 2,   kWDT_TimeoutVal2ToThePowerOf19 = 3,   kWDT_TimeoutVal2ToThePowerOf20 = 4,   kWDT_TimeoutVal2ToThePowerOf21 = 5,   kWDT_TimeoutVal2ToThePowerOf22 = 6,   kWDT_TimeoutVal2ToThePowerOf23 = 7,   kWDT_TimeoutVal2ToThePowerOf24 = 8,   kWDT_TimeoutVal2ToThePowerOf25 = 9,   kWDT_TimeoutVal2ToThePowerOf26 = 10,   kWDT_TimeoutVal2ToThePowerOf27 = 11,   kWDT_TimeoutVal2ToThePowerOf28 = 12,   kWDT_TimeoutVal2ToThePowerOf29 = 13,   kWDT_TimeoutVal2ToThePowerOf30 = 14,   kWDT_TimeoutVal2ToThePowerOf31 = 15 }
	enumeration for wdt timeout value config. More...

Driver version
#define	FSL_WDT_DRIVER_VERSION   (MAKE_VERSION(2, 0, 0))
	WDT driver version 2.0.0. More...

WDT refresh pattern.
#define	WDT_REFRESH_PATTERN   (0x76U)
	Refresh pattern to restart WDT.

Initialization Interfaces
void	WDT_Init (WDT_Type *base, const wdt_config_t *config)
	Initializes the WDT module with input configuration Call this function to do initialization configuration for WDT module. More...
void	WDT_GetDefaultConfig (wdt_config_t *config)
	Prepares an available pre-defined setting for module's configuration. More...

WDT Operation Interfaces
static void	WDT_Enable (WDT_Type *base, bool enable)
	Enable/Disable the WDT module. More...
static void	WDT_SetTimeoutValue (WDT_Type *base, wdt_timeout_value_t timeoutValue)
	Sets the WDT timeout value.
static uint32_t	WDT_GetCounterValue (WDT_Type *base)
	Gets the WDT timeout value.
void	WDT_Refresh (WDT_Type *base)
	Refreshes the WDT timer. More...

Interrupt Control Interfaces
static void	WDT_EnableInterrupt (WDT_Type *base)
	Enables the WDT interrupt, if config->timeoutMode = kWDT_TimeoutModeInterrupt for calling WDT_Init, the WDT interrupt is by default enabled, this function does not take effect. More...
static void	WDT_DisableInterrupt (WDT_Type *base)
	Enables the WDT interrupt, if config->timeoutMode = kWDT_TimeoutModeReset for calling WDT_Init, the WDT interrupt is by default disabled, this function does not take effect. More...

Status get/clear interface.
static bool	WDT_GetInterruptStatus (WDT_Type *base)
	Gets WDT interrupt status. More...
static void	WDT_ClearInterruptStatus (WDT_Type *base)
	Clear WDT interrupt status. More...

---

Data Structure Documentation

struct wdt_config_t

Macro Definition Documentation

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

Enumeration Type Documentation

enum wdt_timeout_response_mode_t

Enumerator
kWDT_ModeTimeoutReset	WDT will generate system reset for timeout.
kWDT_ModeTimeoutInterrupt	WDT will generate interrupt for timeout.

enum wdt_reset_width_t

Enumerator
kWDT_ResetPulseLen2	WDT reset pulse length: 2 pclk cycles.
kWDT_ResetPulseLen4	WDT reset pulse length: 4 pclk cycles.
kWDT_ResetPulseLen8	WDT reset pulse length: 8 pclk cycles.
kWDT_ResetPulseLen16	WDT reset pulse length: 16 pclk cycles.
kWDT_ResetPulseLen32	WDT reset pulse length: 32 pclk cycles.
kWDT_ResetPulseLen64	WDT reset pulse length: 64 pclk cycles.
kWDT_ResetPulseLen128	WDT reset pulse length: 128 pclk cycles.
kWDT_ResetPulseLen256	WDT reset pulse length: 256 pclk cycles.

enum wdt_timeout_value_t

Enumerator
kWDT_TimeoutVal2ToThePowerOf16	WDT timeout value : 2^16 pclk cycles.
kWDT_TimeoutVal2ToThePowerOf17	WDT timeout value : 2^17 pclk cycles.
kWDT_TimeoutVal2ToThePowerOf18	WDT timeout value : 2^18 pclk cycles.
kWDT_TimeoutVal2ToThePowerOf19	WDT timeout value : 2^19 pclk cycles.
kWDT_TimeoutVal2ToThePowerOf20	WDT timeout value : 2^20 pclk cycles.
kWDT_TimeoutVal2ToThePowerOf21	WDT timeout value : 2^21 pclk cycles.
kWDT_TimeoutVal2ToThePowerOf22	WDT timeout value : 2^22 pclk cycles.
kWDT_TimeoutVal2ToThePowerOf23	WDT timeout value : 2^23 pclk cycles.
kWDT_TimeoutVal2ToThePowerOf24	WDT timeout value : 2^24 pclk cycles.
kWDT_TimeoutVal2ToThePowerOf25	WDT timeout value : 2^25 pclk cycles.
kWDT_TimeoutVal2ToThePowerOf26	WDT timeout value : 2^26 pclk cycles.
kWDT_TimeoutVal2ToThePowerOf27	WDT timeout value : 2^27 pclk cycles.
kWDT_TimeoutVal2ToThePowerOf28	WDT timeout value : 2^28 pclk cycles.
kWDT_TimeoutVal2ToThePowerOf29	WDT timeout value : 2^29 pclk cycles.
kWDT_TimeoutVal2ToThePowerOf30	WDT timeout value : 2^30 pclk cycles.
kWDT_TimeoutVal2ToThePowerOf31	WDT timeout value : 2^31 pclk cycles.

Function Documentation

void WDT_Init	(	WDT_Type *	base,
		const wdt_config_t *	config
	)

The configurations are:

• WDT counter timeout value
• Timeout response mode select
• Reset assert pulse width configuration
• WDT enable/disable

  Parameters

  base	WDT peripheral base address.
  config	The pointer to WDT configuration structure, wdt_config_t.

void WDT_GetDefaultConfig

(

wdt_config_t *

config

)

This function initializes the WDT configuration structure to default values. config->timeoutValue = kWDT_TimeoutVal2ToThePowerOf16; config->timeoutMode =kWDT_TimeoutModeReset; config->resetWidth = kWDT_ResetWidthLen2; config->enableWDT = false;

Parameters

config

Pointer to the WDT configuration structure, wdt_config_t.

static void WDT_Enable ( WDT_Type *  base, bool  enable  )

inlinestatic

This function enable/disables the WDT. To disable the WDT Watchdog, call WDT_Enable(base, false).

Parameters

base	WDT peripheral base address.
enable	Enable the feature or not.

void WDT_Refresh

(

WDT_Type *

base

)

This function feeds/services the WDT.

Parameters

base	WDT peripheral base address.

static void WDT_EnableInterrupt ( WDT_Type *  base )

inlinestatic

This function set WDT timeout response mode to generate interrupt.

Parameters

base	WDT peripheral base address

static void WDT_DisableInterrupt ( WDT_Type *  base )

inlinestatic

This function set WDT timeout response mode to generate reset.

Parameters

base	WDT peripheral base address

static bool WDT_GetInterruptStatus ( WDT_Type *  base )

inlinestatic

Parameters

base	WDT peripheral base address

Returns

true if interrupt flag is asserted, else false

static void WDT_ClearInterruptStatus ( WDT_Type *  base )

inlinestatic

Parameters

base	WDT peripheral base address