Functions
fsp_err_t	R_WDT_Refresh (wdt_ctrl_t *const p_ctrl)

fsp_err_t	R_WDT_Open (wdt_ctrl_t const p_ctrl, wdt_cfg_t const const p_cfg)

fsp_err_t	R_WDT_StatusClear (wdt_ctrl_t *const p_ctrl, const wdt_status_t status)

fsp_err_t	R_WDT_StatusGet (wdt_ctrl_t const p_ctrl, wdt_status_t const p_status)

fsp_err_t	R_WDT_CounterGet (wdt_ctrl_t const p_ctrl, uint32_t const p_count)

fsp_err_t	R_WDT_TimeoutGet (wdt_ctrl_t const p_ctrl, wdt_timeout_values_t const p_timeout)

fsp_err_t	R_WDT_CallbackSet (wdt_ctrl_t const p_ctrl, void(p_callback)(wdt_callback_args_t ), void const p_context, wdt_callback_args_t *const p_callback_memory)

Detailed Description

Driver for the WDT peripheral on RX MCUs. This module implements the WDT Interface.

Overview

The watchdog timer is used to recover from unexpected errors in an application. The watchdog timer must be refreshed periodically in the permitted count window by the application. If the count is allowed to underflow or refresh occurs outside of the valid refresh period, the WDT resets the device or generates an IRQ.

Watchdog Timer Operation Example

Features

The WDT HAL module has the following key features:

When the WDT underflows or is refreshed outside of the permitted refresh window, one of the following events can occur:
- Resetting of the device
- Generation of an IRQ
The WDT has two supported modes:
- In auto start mode, the WDT begins counting at reset.
- In register start mode, the WDT can be started from the application.

Selecting a Watchdog

RX MCUs have two watchdog peripherals: the watchdog timer (WDT) and the independent watchdog timer (IWDT). When selecting between them, consider these factors:

	WDT	IWDT
Start Mode	The WDT can be started from the application (register start mode) or configured by hardware to start automatically (auto start mode).	The IWDT can only be configured by hardware to start automatically.
Clock Source	The WDT runs off a peripheral clock.	The IWDT has its own clock source which improves safety.

Configuration

The configuration of start mode setting is on the BSP tab. The default setting for the start mode is register start mode.

When using register start mode, no need to update the configuration of start mode on the BSP tab. Configure the watchdog timer on the Stacks tab.

Note: When using auto start mode, configurations on the Stacks tab are ignored. Configure the watchdog using the OFS settings on the BSP tab.

Build Time Configurations for r_wdt

The following build time configurations are defined in fsp_cfg/r_wdt_cfg.h:

Configuration	Options	Default	Description
Parameter Checking	Default (BSP) Enabled Disabled	Default (BSP)	If selected code for parameter checking is included in the build.
NMI Support	Disabled	Disabled	NMI is not supported.
IRQ Support	Enabled Disabled	Disabled	If enabled, code for IRQ support is included in the build.

Configurations for Monitoring > Watchdog (r_wdt)

This module can be added to the Stacks tab via New Stack > Monitoring > Watchdog (r_wdt).

Configuration	Options	Default	Description
Name	Name must be a valid C symbol	g_wdt0	Module name.
Timeout	1,024 Cycles 4,096 Cycles 8,192 Cycles 16,384 Cycles	16,384 Cycles	Select the watchdog timeout in cycles.
Clock Division Ratio	PCLK/4 PCLK/64 PCLK/128 PCLK/512 PCLK/2048 PCLK/8192	PCLK/8192	Select the watchdog clock divisor.
Window Start Position	100 (Window Position Not Specified) 75 50 25	100 (Window Position Not Specified)	Select the allowed watchdog refresh start point in %.
Window End Position	0 (Window Position Not Specified) 25 50 75	0 (Window Position Not Specified)	Select the allowed watchdog refresh end point in %.
Reset Control	Reset Output IRQ Output	Reset Output	Select what happens when the watchdog timer expires.(NMI request output is not supported)
Stop Control	MCU Specific Options		Select the watchdog state in low power mode.
NMI/IRQ Callback	Name must be a valid C symbol	NULL	A user callback function must be provided if the WDT is configured to generate an NMI or IRQ when the timer underflows or a refresh error occurs. If this callback function is provided, it will be called from the NMI/IRQ handler each time the watchdog triggers.
IRQ Priority	MCU Specific Options		Select the WDT interrupt priority.

Clock Configuration

The WDT clock is based on the PCLKB frequency. You can set the PCLKB frequency using the Clocks tab of the RX Configuration editor or by using the CGC Interface at run-time. The maximum timeout period with PCLKB running at 60 MHz is approximately 2.2 seconds.

Pin Configuration

This module does not use I/O pins.

Usage Notes

NMI Interrupt

The watchdog timer uses the NMI, which is enabled by default. No special configuration is required. When the NMI is triggered, the callback function registered during open is called.

Note: NMI request output is not supported in WDT module.

IRQ Interrupt

The watchdog timer uses an IRQ, and the interrupt priority level must be configured before use. When the IRQ is triggered, the callback function registered during open is called.

Note: When using the WDT in software start mode with IRQ and the timer underflows, the WDT status must be reset by calling R_WDT_StatusClear before restarting the timer via R_WDT_Refresh.

Period Calculation

The WDT operates from PCLKB. With a PCLKB of 60 MHz, the maximum time from the last refresh to device reset or IRQ generation will be just over 2.2 seconds as detailed below.

PLCKB = 60 MHz
Clock division ratio = PCLKB / 8192
Timeout period = 16384 cycles
WDT clock frequency = 60 MHz / 8192 = 7.324 kHz
Cycle time = 1 / 7.324 kHz = 136.53 us
Timeout = 136.53 us x 16384 cycles = 2.23 seconds

Limitations

Developers should be aware of the following limitations when using the WDT:

NMI request output is not supported in WDT module. Please use Reset Output or IRQ Output only for the configuration of Reset Control.
If the WDT is configured to stop the counter in low power mode, then your application must restart the watchdog by calling R_WDT_Refresh() after the MCU wakes from low power mode.

Examples

WDT Basic Example

This is a basic example of minimal use of the WDT in an application.

void wdt_basic_example (void)
{
    fsp_err_t err = FSP_SUCCESS;
    /* In auto start mode, the WDT starts counting immediately when the MCU is powered on. */
    /* Initializes the module. */
    err = R_WDT_Open(&g_wdt0_ctrl, &g_wdt0_cfg);
    /* Handle any errors. This function should be defined by the user. */
    assert(FSP_SUCCESS == err);
    /* In register start mode, start the watchdog by calling R_WDT_Refresh. */
    err = R_WDT_Refresh(&g_wdt0_ctrl);
    assert(FSP_SUCCESS == err);
    while (true)
    {
        /* Application work here. */
        /* Refresh before the counter underflows to prevent reset. */
        err = R_WDT_Refresh(&g_wdt0_ctrl);
        assert(FSP_SUCCESS == err);
    }
}

WDT Advanced Example

This example demonstrates using a start window for refreshing before the counter underflows to prevent reset.

#define WDT_TIMEOUT_COUNTS     (16384U)
#define WDT_MAX_COUNTER        (WDT_TIMEOUT_COUNTS - 1U)
#define WDT_START_WINDOW_75    ((WDT_MAX_COUNTER * 3) / 4)
void wdt_advanced_example (void)
{
    fsp_err_t err = FSP_SUCCESS;
    /* (Optional) Check if the WDTRF flag is set to know if the system is
     * recovering from a WDT reset. */
    if (R_SYSTEM->RSTSR1_b.WDT0RF)
    {
        /* Clear the flag. */
        R_SYSTEM->RSTSR1 = 0U;
    }
    /* Open the module. */
    err = R_WDT_Open(&g_wdt0_ctrl, &g_wdt0_cfg);
    /* Handle any errors. This function should be defined by the user. */
    assert(FSP_SUCCESS == err);
    /* Initialize other application code. */
    /* (Register start mode) Call R_WDT_Refresh() to start the WDT in register
     * start mode.  Do not call R_WDT_Refresh() in auto start mode unless the
     * counter is in the acceptable refresh window. */
    err = R_WDT_Refresh(&g_wdt0_ctrl);
    assert(FSP_SUCCESS == err);
    while (true)
    {
        /* Application work here. */
        /* (Optional) If there is a chance the application takes less time than
         * the start window, verify the WDT counter is past the start window
         * before refreshing the WDT. */
        uint32_t wdt_counter = 0U;
        do
        {
            /* Read the current WDT counter value. */
            err = R_WDT_CounterGet(&g_wdt0_ctrl, &wdt_counter);
            assert(FSP_SUCCESS == err);
        } while (wdt_counter >= WDT_START_WINDOW_75);
        /* Refresh before the counter underflows to prevent reset. */
        err = R_WDT_Refresh(&g_wdt0_ctrl);
        assert(FSP_SUCCESS == err);
    }
}

Data Structures
struct	wdt_instance_ctrl_t

struct	wdt_extended_cfg_t

Data Structure Documentation

◆ wdt_instance_ctrl_t

struct wdt_instance_ctrl_t

WDT private control block. DO NOT MODIFY. Initialization occurs when R_WDT_Open() is called.

◆ wdt_extended_cfg_t

struct wdt_extended_cfg_t

WDT Extended Configuration

Data Fields
IRQn_Type	irq	WUNI interrupt number.
uint8_t	ipl	WUNI interrupt priority.

Function Documentation

◆ R_WDT_Refresh()

fsp_err_t R_WDT_Refresh ( wdt_ctrl_t *const p_ctrl )

Refresh the watchdog timer. Implements wdt_api_t::refresh.

In addition to refreshing the watchdog counter this function can be used to start the counter in register start mode.

Example:

        /* Refresh before the counter underflows to prevent reset. */
        err = R_WDT_Refresh(&g_wdt0_ctrl);
        assert(FSP_SUCCESS == err);

Return values

FSP_SUCCESS	WDT successfully refreshed.
FSP_ERR_ASSERTION	p_ctrl is NULL.
FSP_ERR_NOT_OPEN	Instance control block is not initialized.

Note: This function only returns FSP_SUCCESS. If the refresh fails due to being performed outside of the permitted refresh period the device will either reset or trigger an NMI/IRQ ISR to run.

◆ R_WDT_Open()

fsp_err_t R_WDT_Open	(	wdt_ctrl_t *const	p_ctrl,
		wdt_cfg_t const *const	p_cfg
	)

Configure the WDT in register start mode. In auto-start_mode the NMI/IRQ callback can be registered. Implements wdt_api_t::open.

This function should only be called once as WDT configuration registers can only be written to once so subsequent calls will have no effect.

Example:

    /* Initializes the module. */
    err = R_WDT_Open(&g_wdt0_ctrl, &g_wdt0_cfg);

Return values

FSP_SUCCESS	WDT successfully configured.
FSP_ERR_ASSERTION	Null pointer, or one or more configuration options is invalid.
FSP_ERR_ALREADY_OPEN	Module is already open. This module can only be opened once.

Note: In auto start mode the only valid configuration option is for registering the callback for the NMI/IRQ ISR if NMI/IRQ output has been selected.

◆ R_WDT_StatusClear()

fsp_err_t R_WDT_StatusClear	(	wdt_ctrl_t *const	p_ctrl,
		const wdt_status_t	status
	)

Clear the WDT status and error flags. Implements wdt_api_t::statusClear.

Return values

FSP_SUCCESS	WDT flag(s) successfully cleared.
FSP_ERR_ASSERTION	Null pointer as a parameter.
FSP_ERR_NOT_OPEN	Instance control block is not initialized.
FSP_ERR_UNSUPPORTED	This function is only valid if the watchdog generates an NMI/IRQ when an error occurs.

Note: When the WDT is configured to output a reset on underflow or refresh error reading the status and error flags serves no purpose as they will always indicate that no underflow has occurred and there is no refresh error. Reading the status and error flags is only valid when interrupt request output is enabled.

◆ R_WDT_StatusGet()

fsp_err_t R_WDT_StatusGet	(	wdt_ctrl_t *const	p_ctrl,
		wdt_status_t *const	p_status
	)

Read the WDT status flags. Implements wdt_api_t::statusGet.

Indicates both status and error conditions.

Return values

FSP_SUCCESS	WDT status successfully read.
FSP_ERR_ASSERTION	Null pointer as a parameter.
FSP_ERR_NOT_OPEN	Instance control block is not initialized.
FSP_ERR_UNSUPPORTED	This function is only valid if the watchdog generates an NMI/IRQ when an error occurs.

Note: When the WDT is configured to output a reset on underflow or refresh error reading the status and error flags serves no purpose as they will always indicate that no underflow has occurred and there is no refresh error. Reading the status and error flags is only valid when interrupt request output is enabled.

◆ R_WDT_CounterGet()

fsp_err_t R_WDT_CounterGet	(	wdt_ctrl_t *const	p_ctrl,
		uint32_t *const	p_count
	)

Read the current count value of the WDT. Implements wdt_api_t::counterGet.

Example:

            /* Read the current WDT counter value. */
            err = R_WDT_CounterGet(&g_wdt0_ctrl, &wdt_counter);
            assert(FSP_SUCCESS == err);

Return values

FSP_SUCCESS	WDT current count successfully read.
FSP_ERR_ASSERTION	Null pointer passed as a parameter.
FSP_ERR_NOT_OPEN	Instance control block is not initialized.

◆ R_WDT_TimeoutGet()

fsp_err_t R_WDT_TimeoutGet	(	wdt_ctrl_t *const	p_ctrl,
		wdt_timeout_values_t *const	p_timeout
	)

Read timeout information for the watchdog timer. Implements wdt_api_t::timeoutGet.

Return values

FSP_SUCCESS	WDT timeout information retrieved successfully.
FSP_ERR_ASSERTION	Null Pointer.
FSP_ERR_NOT_OPEN	Instance control block is not initialized.

◆ R_WDT_CallbackSet()

fsp_err_t R_WDT_CallbackSet	(	wdt_ctrl_t *const	p_ctrl,
		void()(wdt_callback_args_t )	p_callback,
		void *const	p_context,
		wdt_callback_args_t *const	p_callback_memory
	)

Updates the user callback and has option of providing memory for callback structure. Implements wdt_api_t::callbackSet

Return values

FSP_SUCCESS	Callback updated successfully.
FSP_ERR_ASSERTION	A required pointer is NULL.
FSP_ERR_NOT_OPEN	The control block has not been opened.

Functions

Detailed Description

Overview

Features

Selecting a Watchdog

Configuration

Build Time Configurations for r_wdt

Configurations for Monitoring > Watchdog (r_wdt)

Clock Configuration

Pin Configuration

Usage Notes

NMI Interrupt

IRQ Interrupt

Period Calculation

Limitations

Examples

WDT Basic Example

WDT Advanced Example

Data Structures

Data Structure Documentation

◆ wdt_instance_ctrl_t

◆ wdt_extended_cfg_t

Function Documentation

◆ R_WDT_Refresh()

◆ R_WDT_Open()

◆ R_WDT_StatusClear()

◆ R_WDT_StatusGet()

◆ R_WDT_CounterGet()

◆ R_WDT_TimeoutGet()

◆ R_WDT_CallbackSet()