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 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. If the count is allowed to overflow occurs, the WDT resets the device.

Watchdog Timer Operation Example

Features

The WDT HAL module has the following key features:

• When the WDT overflowflow twice, the following event can occur:
  • Resetting of the device
• 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.
Timeout(s)	Value must be non-negative between 0.04369 and 178.9	60	Select the time before the WDT counter overflows. (A single overflow does not generate a reset.)
Overflow Interrupt Priority	Value must be an integer between 0 and 31	24	Select the overflow interrupt priority.
Callback	Name must be a valid C symbol	NULL	A user callback function can be provided.

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 178.9 seconds.

Pin Configuration

This WDT uses the following pin.

• WDTOVF_PERROUT: Watchdog timer counter overflow signal output.

Usage Notes

Period Calculation

The RZ/A3UL configuration editor can directly enter the timeout period (seconds) until overflow. The selectable timeout time (seconds) is from 0.04369(s) to 178.9(s).

Below is an example of calculating the maximum timeout time when OSCLK is 24MHz.

OSCCLK = 24 MHz
Timeout period = 1024 * 1024 * 4096 = 4294967296 cycles
(4095 : Register Settimg Max Value)
Cycle time = 1 / 24 MHz = 41.66 ns
Timeout = 41.66 us x 4294967296 cycles = 178.9 seconds

Limitations

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

• When using a J-Link debugger the WDT counter does not count and therefore will not reset the device. To enable the watchdog to count and generate a resetwhile debugging, add this line of code in the application:

  
      /* Enable system reset due to WDT. */
      R_CPG->CPG_WDTRST_SEL = R_CPG_CPG_WDTRST_SEL_WDTRSTSEL0_Msk | R_CPG_CPG_WDTRST_SEL_WDTRSTSEL0_WEN_Msk;
  

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;


    /* 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);

    /* Call R_WDT_Refresh to start the watchdog. */
    err = R_WDT_Refresh(&g_wdt0_ctrl);
    assert(FSP_SUCCESS == err);

    while (true)
    {
        /* Application work here. */


        /* Refresh before the counter overflows. */
        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 interrupt generated by an overflow.

#define WDT_START_WINDOW_75    ((1024 * 1024 * WDT_COUNT_CYCLE_VALUE) * 3 / 4 - 1)

/* 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) 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. */
    R_CPG->CPG_WDTRST_SEL = R_CPG_CPG_WDTRST_SEL_WDTRSTSEL0_Msk | R_CPG_CPG_WDTRST_SEL_WDTRSTSEL0_WEN_Msk;


    /* (Optional) Check if the WDTOVF flag is set to know if the system is
     * recovering from a WDT reset. */
    if (R_CPG->CPG_WDTOVF_RST_b.WDTOVF0)
    {
        R_CPG->CPG_WDTOVF_RST = R_CPG_CPG_WDTOVF_RST_WDTOVF0_Msk | R_CPG_CPG_WDTOVF_RST_WDTOVF0_WEN_Msk;
    }

    /* 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. */

    /* Call R_WDT_Refresh() to start the WDT. */
    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 overflows 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 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.

Example:

        /* Refresh before the counter overflows. */
        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.