Watchdog (r_wdt)

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 *const p_context, wdt_callback_args_t *const p_callback_memory)

Detailed Description

Driver for the WDT peripheral on RZ MPUs. 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 can be started from the application.

Configuration

When using register start mode, configure the watchdog timer on the Stacks 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.

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.
Channel	MCU Specific Options		Check User's Manual: Hardware to see which CPU a channel is for.
Timeout	MCU Specific Options		Select the watchdog timeout in cycles.
Clock Division Ratio	MCU Specific Options		Select the watchdog clock divisor.
Window Start Position	MCU Specific Options		Select the allowed watchdog refresh start point in %.
Window End Position	MCU Specific Options		Select the allowed watchdog refresh end point in %.
WDT Counting	MCU Specific Options		Select to enable or disable WDT counting. It is recommended to set "WDT Counting" to "Disabled" to avoid unintentional WDT interrupt occurs when debugging the user program.
System Reset	MCU Specific Options		Select to enable or disable system reset due to a request by WDT.
WDTUDFOUT Assertion	MCU Specific Options		Select to enable or disable the assertion of WDTUDFOUT due to a request by WDT.
Cold Reset	MCU Specific Options		Select to enable or disable the cold reset due to a request by WDT.
Underflow Interrupt Enable	MCU Specific Options		Enable the WDT underflow interrupt.
Underflow Interrupt Priority	Value must be an integer between 0 and 255	8	Select the underflow interrupt priority.
WDT 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 when the timer underflows or a refresh error occurs. If this callback function is provided, it will be called from the NMI handler each time the watchdog triggers.

Clock Configuration

The WDT clock is based on the OSCCLK frequency. You can not set the OSCCLK frequency using the Clocks tab of the RZ Configuration editor or by using the CGC Interface at run-time. The maximum timeout period with OSCCLK running at 24 MHz is approximately 0.175 seconds.

Pin Configuration

This WDT uses the following pin.

• WDTUDF_PERROUT: Watchdog timer counter underflow signal output.

Usage Notes

Period Calculation

The WDT operates from OSCCLK. With a OSCCLK of 24 MHz, the maximum time from the last refresh to device reset or IRQ generation will be just over 0.175 seconds as detailed below.

OSCCLK = 24 MHz
Clock division ratio = OSCCLK / 256
Timeout period = 16384 cycles
WDT clock frequency = 24 MHz / 256 = 93.750 kHz
Cycle time = 1 / 93.750 kHz = 10.667 us
Timeout = 10.667 us x 16384 cycles = 0.175 seconds

Limitations

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

• 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.
• When WDT counting starts, it keeps running even if the user program is stopped at a breakpoint by the debugger. Then an unintentional WDT interrupt occurs. To avoid such cases, it is recommended to set "WDT Counting" to "Disabled" when debugging.

WDT Interrupt

WDT interrupt to CPU are prohibited in specific core.

Device	Core	WDT interrupt to CPU
RZ/V2H	CM33	Prohibited
	CR8	Not prohibited

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 or NMI. */
        err = R_WDT_Refresh(&g_wdt0_ctrl);
        assert(FSP_SUCCESS == err);

    }
}

WDT Advanced Example

This example demonstrates using a start window and gives an example callback to handle an IRQ generated by an underflow or refresh error.

#define WDT_TIMEOUT_COUNTS     (16384U)
#define WDT_MAX_COUNTER        (WDT_TIMEOUT_COUNTS - 1U)
#define WDT_START_WINDOW_75    ((WDT_MAX_COUNTER * 3) / 4)

/* Example callback called when a watchdog NMI occurs. */
void wdt_callback (wdt_callback_args_t * p_args)
{
    FSP_PARAMETER_NOT_USED(p_args);
    fsp_err_t err = FSP_SUCCESS;


    /* (Optional) Determine the source of the NMI. */
    wdt_status_t status = WDT_STATUS_NO_ERROR;
    err = R_WDT_StatusGet(&g_wdt0_ctrl, &status);
    assert(FSP_SUCCESS == err);


    /* (Optional) Log source of NMI and any other debug information. */


    /* (Optional) Clear the error flags. */
    err = R_WDT_StatusClear(&g_wdt0_ctrl, status);
    assert(FSP_SUCCESS == err);


    /* Call R_WDT_Refresh() to continue using the watchdog after an error. */
    err = R_WDT_Refresh(&g_wdt0_ctrl);
    assert(FSP_SUCCESS == err);
}

void wdt_advanced_example (void)
{
    fsp_err_t err = FSP_SUCCESS;


    /* Enable system reset due to WDT. */
    wdt_extended_cfg_t g_wdt0_cfg_extend_0 =
    {
        .channel                    = 0,
        .wdt_counting_enable        = true,
        .system_reset_enable        = true,
        .wdtudfout_assertion_enable = false,
        .cold_reset_enable          = false,
        .underflow_ipl              = 8,
        .underflow_irq              = FSP_INVALID_VECTOR,
    };


    const wdt_cfg_t g_wdt0_cfg_0 =
    {
        .timeout        = WDT_TIMEOUT_16384,
        .clock_division = WDT_CLOCK_DIVISION_256,
        .window_start   = WDT_WINDOW_START_100,
        .window_end     = WDT_WINDOW_END_0,
        .reset_control  = WDT_RESET_CONTROL_NMI,
        .stop_control   = WDT_STOP_CONTROL_DISABLE,
        .p_callback     = NULL,
        .p_context      = NULL,
        .p_extend       = &g_wdt0_cfg_extend_0,
    };

    /* (Optional) Check if the error system reset flag for WDT is set to know if the system is
     * recovering from a WDT reset. */
    if (R_CPG->CPG_ERROR_RST2 & R_CPG_CPG_ERROR_RST2_ERROR_RST0_Msk)
    {
        R_CPG->CPG_ERROR_RST2 = R_CPG_CPG_ERROR_RST2_ERROR_RST0_Msk | R_CPG_CPG_ERROR_RST2_ERROR_RST0_WEN_Msk;
    }

    /* Open the module. */
    err = R_WDT_Open(&g_wdt0_ctrl, &g_wdt0_cfg_0);

    /* 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 or NMI. */
        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 configuration extension. This extension is required.

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 or NMI. */
        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.

R_WDT_Open()

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

Configures the WDT driver based on the input configurations. This function sets the callback function, the timeout count value, and enables the overflow interrupt. 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.

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.

Example:

    /* (Optional) Clear the error flags. */
    err = R_WDT_StatusClear(&g_wdt0_ctrl, status);
    assert(FSP_SUCCESS == err);

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.

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.

Example:

    /* (Optional) Determine the source of the NMI. */
    wdt_status_t status = WDT_STATUS_NO_ERROR;
    err = R_WDT_StatusGet(&g_wdt0_ctrl, &status);
    assert(FSP_SUCCESS == err);

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.

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 *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.
FSP_ERR_NO_CALLBACK_MEMORY	p_callback is non-secure and p_callback_memory is either secure or NULL.