Functions
fsp_err_t	R_LVD_Open (lvd_ctrl_t const p_api_ctrl, lvd_cfg_t const const p_cfg)

fsp_err_t	R_LVD_StatusGet (lvd_ctrl_t const p_api_ctrl, lvd_status_t p_lvd_status)

fsp_err_t	R_LVD_StatusClear (lvd_ctrl_t *const p_api_ctrl)

fsp_err_t	R_LVD_CallbackSet (lvd_ctrl_t const p_api_ctrl, void(p_callback)(lvd_callback_args_t ), void const const p_context, lvd_callback_args_t *const p_callback_memory)

fsp_err_t	R_LVD_Close (lvd_ctrl_t *const p_api_ctrl)

Detailed Description

Driver for the LVD and PVD peripherals on RA MCUs. This module implements the Low Voltage Detection Interface.

Note: In the below usage notes, "LVD" refers to both LVD and PVD.

Overview

The Low Voltage Detection module configures the voltage monitors to detect when a power supply pin or a voltage detector pin voltages crosses a specified threshold.

Features

The LVD HAL module supports the following functions:

Five run-time configurable voltage monitors (Voltage Monitor 1, Voltage Monitor 2, LVD VBAT, LVD VRTC, EXLVD)
- Configurable voltage threshold
- Digital filter (Available on specific MCUs)
- Support for both interrupt or polling
  - NMI or maskable interrupt can be configured (NMI support for Voltage Monitor 1 & Voltage Monitor 2 only).
- Voltage monitor interrupt generation condition can be configured (rising, falling, or both edge event detection).
- Support for resetting the MCU when V_CC falls below/rises above configured threshold.

Configuration

Build Time Configurations for r_lvd

The following build time configurations are defined in fsp_cfg/r_lvd_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 > Low/Programmable Voltage Detection (r_lvd)

This module can be added to the Stacks tab via New Stack > Monitoring > Low/Programmable Voltage Detection (r_lvd). Non-secure callable guard functions can be generated for this module by right clicking the module in the RA Configuration tool and checking the "Non-secure Callable" box.

Configuration	Options	Default	Description
Name	Name must be a valid C symbol	g_lvd0	Module name.
Monitor Number	MCU Specific Options		Select the LVD monitor.
Digital Filter	MCU Specific Options		Enable the digital filter and select the digital filter clock divider.
Voltage Threshold	MCU Specific Options		Select the low voltage detection threshold.
Detection Response	MCU Specific Options		Select what happens when the voltage crosses the threshold voltage.
Voltage Slope	MCU Specific Options		Select interrupt generation on rising voltage, falling voltage or both.
Negation Delay	MCU Specific Options		Negation of the monitor signal can either be delayed from the reset event or from voltage returning to normal range.
Monitor Interrupt Callback	Name must be a valid C symbol.	NULL	A user callback function can be provided. If this callback function is provided, it will be called from the interrupt service routine (ISR) each time the IRQ triggers.
LVD Monitor Interrupt Priority	MCU Specific Options		Select the LVD Monitor interrupt priority.

Clock Configuration

The LOCO clock must be enabled in order to use the digital filter.

Pin Configuration

To use LVD module, you need to switch pin funtion of EXLVDVBAT pin, VRTC pin, EXLVD pin to enable LVD function on this pin.

Usage Notes

Startup Edge Detection

If V_CC is below the threshold prior to configuring the voltage monitor for falling edge detection, the monitor will immediately detect the a falling edge condition. If V_CC is above the threshold prior to configuring the monitor for rising edge detection, the monitor will not detect a rising edge condition until V_CC falls below the threshold and then rises above it again.

Voltage Monitor 0

The LVD HAL module only supports configuring voltage monitor 1 and voltage monitor 2. Voltage monitor 0 can be configured by setting the appropriate bits in the OFS1 register. This means that voltage monitor 0 settings cannot be changed at runtime.

Voltage monitor 0 supports the following features

Configurable Voltage Threshold (V_DET0)
Reset the device when V_CC falls below V_DET0

Limitations

The digital filter must be disabled when using voltage monitors in Software Standby or Deep Software Standby.
Deep Software Standby mode is not possible if the voltage monitor is configured to reset the MCU.
Reset generated by the VCC-rise detection is supported only on devices with PVD.
On RA0, when LVD0 is used the detection voltage of LVD1 must be higher than LVD0's. See the section "LVD1CR : Voltage Monitor 1 Circuit Control Register" of the RA0 Hardware User's Manual (r01uh1040ej0100).

Examples

Basic Example

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

void basic_example (void)
{
    fsp_err_t err = R_LVD_Open(&g_lvd_ctrl, &g_lvd_cfg);
    assert(FSP_SUCCESS == err);
    while (1)
    {
        lvd_status_t status;
        err = R_LVD_StatusGet(&g_lvd_ctrl, &status);
        assert(FSP_SUCCESS == err);
        if (LVD_THRESHOLD_CROSSING_DETECTED == status.crossing_detected)
        {
            err = R_LVD_StatusClear(&g_lvd_ctrl);
            assert(FSP_SUCCESS == err);
            /* Do something */
        }
    }
}

Interrupt Example

This is a basic example of using a LVD instance that is configured to generate an interrupt.

void interrupt_example (void)
{
    fsp_err_t err = R_LVD_Open(&g_lvd_ctrl, &g_lvd_cfg);
    /* Handle any errors. This function should be defined by the user. */
    assert(FSP_SUCCESS == err);
    while (1)
    {
        /* Application Process */
        /* Application will be interrupted when Vcc crosses the configured threshold. */
    }
}
/* Called when Vcc crosses configured threshold. */
void lvd_callback (lvd_callback_args_t * p_args)
{
    if (LVD_CURRENT_STATE_BELOW_THRESHOLD == p_args->current_state)
    {
        /* Do Something */
    }
}

Reset Example

This is a basic example of using a LVD instance that is configured to reset the MCU.

void reset_example (void)
{
    if (1U == R_SYSTEM->RSTSR0_b.LVD1RF)
    {
        /* The system is coming out of reset because Vcc crossed configured voltage threshold. */
        /* Clear Voltage Monitor 1 Reset Detect Flag. */
        R_SYSTEM->RSTSR0_b.LVD1RF = 0;
    }
    fsp_err_t err = R_LVD_Open(&g_lvd_ctrl, &g_lvd_cfg);
    /* Handle any errors. This function should be defined by the user. */
    assert(FSP_SUCCESS == err);
    while (1)
    {
        /* Application Process */
        /* Application will reset when Vcc crosses the configured threshold. */
    }
}

Data Structures
struct	lvd_instance_ctrl_t

Data Structure Documentation

◆ lvd_instance_ctrl_t

struct lvd_instance_ctrl_t

LVD instance control structure

Function Documentation

◆ R_LVD_Open()

fsp_err_t R_LVD_Open	(	lvd_ctrl_t *const	p_api_ctrl,
		lvd_cfg_t const *const	p_cfg
	)

Initializes a voltage monitor and detector according to the passed-in configuration structure.

Parameters

[in]	p_api_ctrl	Pointer to the control structure for the driver instance
[in]	p_cfg	Pointer to the configuration structure for the driver instance

Note: Digital filter is not to be used with standby modes.; Startup time can take on the order of milliseconds for some configurations.

Example:

fsp_err_t err = R_LVD_Open(&g_lvd_ctrl, &g_lvd_cfg);

Return values

FSP_SUCCESS	Successful
FSP_ERR_ASSERTION	Requested configuration was invalid
FSP_ERR_ALREADY_OPEN	The instance was already opened
FSP_ERR_IN_USE	Another instance is already using the desired monitor
FSP_ERR_UNSUPPORTED	Digital filter was enabled on a device that does not support it

◆ R_LVD_StatusGet()

fsp_err_t R_LVD_StatusGet	(	lvd_ctrl_t *const	p_api_ctrl,
		lvd_status_t *	p_lvd_status
	)

Get the current state of the monitor (threshold crossing detected, voltage currently above or below threshold).

Parameters

[in]	p_api_ctrl	Pointer to the control structure for the driver instance
[out]	p_lvd_status	Pointer to status structure

Example:

err = R_LVD_StatusGet(&g_lvd_ctrl, &status);

Return values

FSP_SUCCESS	Successful
FSP_ERR_ASSERTION	An argument was NULL
FSP_ERR_NOT_OPEN	Driver is not open

◆ R_LVD_StatusClear()

fsp_err_t R_LVD_StatusClear ( lvd_ctrl_t *const p_api_ctrl )

Clears the latched status of the monitor.

Parameters

[in] p_api_ctrl Pointer to the control structure for the driver instance

Return values

FSP_SUCCESS	Successful
FSP_ERR_ASSERTION	An argument was NULL
FSP_ERR_NOT_OPEN	Driver is not open

◆ R_LVD_CallbackSet()

fsp_err_t R_LVD_CallbackSet	(	lvd_ctrl_t *const	p_api_ctrl,
		void()(lvd_callback_args_t )	p_callback,
		void const *const	p_context,
		lvd_callback_args_t *const	p_callback_memory
	)

Updates the user callback and has option of providing memory for callback structure. Implements lvd_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.

◆ R_LVD_Close()

fsp_err_t R_LVD_Close ( lvd_ctrl_t *const p_api_ctrl )

Disables the LVD peripheral. Closes the driver instance.

Parameters

[in] p_api_ctrl Pointer to the control block structure for the driver instance

Return values

FSP_SUCCESS	Successful
FSP_ERR_ASSERTION	An argument was NULL
FSP_ERR_NOT_OPEN	Driver is not open

Functions

Detailed Description

Overview

Features

Configuration

Build Time Configurations for r_lvd

Configurations for Monitoring > Low/Programmable Voltage Detection (r_lvd)

Clock Configuration

Pin Configuration

Usage Notes

Startup Edge Detection

Voltage Monitor 0

Limitations

Examples

Basic Example

Interrupt Example

Reset Example

Data Structures

Data Structure Documentation

◆ lvd_instance_ctrl_t

Function Documentation

◆ R_LVD_Open()

◆ R_LVD_StatusGet()

◆ R_LVD_StatusClear()

◆ R_LVD_CallbackSet()

◆ R_LVD_Close()