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samples: boards: renesas: Add sample for RX LVD driver
Add a simple sample for LVD driver on RSK-RX130-512kb Signed-off-by: Quy Tran <[email protected]>
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‎samples/boards/renesas/lvd/CMakeLists.txt

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# Copyright (c) 2025 Renesas Electronics Corporation
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# SPDX-License-Identifier: Apache-2.0
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cmake_minimum_required(VERSION 3.20.0)
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find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
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project(lvd)
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FILE(GLOB app_sources src/*.c)
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target_sources(app PRIVATE src/main.c)

‎samples/boards/renesas/lvd/README.rst

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.. zephyr:code-sample:: renesas-lvd
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:name: Renesas Low-voltage Detection Sample
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Demonstrates monitoring and reacting to voltage levels.
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Overview
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********
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This sample application shows how to use the Renesas Low-voltage Detection (LVD)
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driver in Zephyr to monitor supply voltage and indicate status via LEDs.
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The app reads the voltage status, handles LVD interrupts, and updates
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LEDs based on whether the voltage is above or below a configured threshold.
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Features
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********
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- Reads voltage status from the LVD peripheral.
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- Handles LVD interrupts (if enabled in device tree/config).
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- Indicates voltage status using two LEDs:
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- LED_ABOVE: On when voltage is above threshold.
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- LED_BELOW: On when voltage is below threshold.
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- Prints status messages to the console.
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Hardware Setup
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**************
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- Ensure that the monitored target pin is supplied with power.
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Building and Running
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********************
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To build and flash the sample on a supported Renesas RX board:
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.. zephyr-app-commands::
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:zephyr-app: samples/boards/renesas/lvd
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:board: rsk_rx130@512kb
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:goals: build flash
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:compact:
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Usage
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*****
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- On startup, the app prints the configured voltage threshold.
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- The app continuously monitors the voltage:
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- If voltage is **above** the threshold, LED_ABOVE is turned on, LED_BELOW is off.
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- If voltage is **below** the threshold, LED_BELOW is turned on, LED_ABOVE is off.
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- If LVD interrupt is enabled, voltage changes will trigger an interrupt and update the
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status immediately.
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Customization
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*************
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- You can change the voltage threshold and LVD action via device tree properties.
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- LED pins can be reassigned by modifying the ``led0`` and ``led1`` aliases in your
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board's DTS.
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Example Output
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**************
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::
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===========================================================
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LVD Voltage Monitoring Sample Started
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Threshold Voltage Level : 384 mV
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===========================================================
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[LVD Init] Voltage is ABOVE threshold (384 mV)
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[LVD] Interrupt: Voltage level crossing detected!
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[WARNING] Voltage instability detected! Check power supply.
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[LVD] Voltage is BELOW threshold (384 mV)

‎samples/boards/renesas/lvd/boards/rsk_rx130_512kb.overlay

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/*
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* Copyright (c) 2025 Renesas Electronics Corporation
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* SPDX-License-Identifier: Apache-2.0
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*/
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&pinctrl {
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lvd1_default: lvd1_default {
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group1 {
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/* CMPA2 */
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psels = <RX_PSEL(RX_PSEL_LVD, 14, 4)>;
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renesas,analog-enable;
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input-enable;
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};
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};
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};
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&lvd1 {
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pinctrl-0 = <&lvd1_default>;
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pinctrl-names = "default";
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lvd-action = "maskable-interrupt";
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voltage-level = <384>;
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vdet-target = "cmpa";
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lvd-trigger = "rising";
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lvd-stabilization = <0>;
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status = "okay";
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};

‎samples/boards/renesas/lvd/prj.conf

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CONFIG_LOG=y

‎samples/boards/renesas/lvd/sample.yaml

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sample:
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name: Low Voltage Detector (LVD)
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tests:
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sample.boards.renesas.lvd:
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build_only: true
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platform_allow:
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- rsk_rx130@512kb
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tags: lvd

‎samples/boards/renesas/lvd/src/main.c

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/*
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* Copyright (c) 2025 Renesas Electronics Corporation
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr/sys/util.h>
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#include <zephyr/drivers/misc/renesas_lvd/renesas_lvd.h>
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#include <zephyr/drivers/gpio.h>
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#include <zephyr/devicetree.h>
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#include <zephyr/kernel.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdbool.h>
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/* LVD node & config from Device Tree */
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#if DT_HAS_COMPAT_STATUS_OKAY(renesas_rx_lvd)
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#define LVD_NODE DT_INST(0, renesas_rx_lvd)
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#endif
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#define LVD_ACTION DT_ENUM_IDX(LVD_NODE, lvd_action)
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#define VOLTAGE_THRESHOLD DT_PROP(LVD_NODE, voltage_level)
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/* GPIO LEDs */
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#define LED_BELOW_NODE DT_ALIAS(led0)
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#define LED_ABOVE_NODE DT_ALIAS(led1)
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static const struct gpio_dt_spec led_below = GPIO_DT_SPEC_GET(LED_BELOW_NODE, gpios);
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static const struct gpio_dt_spec led_above = GPIO_DT_SPEC_GET(LED_ABOVE_NODE, gpios);
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/* Semaphore for LVD interrupt */
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static struct k_sem lvd_sem;
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#if LVD_ACTION == 2
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#define LVD_INT 1
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#else
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#define LVD_INT 0
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#endif
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#if LVD_INT
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void user_callback(const struct device *dev, void *user_data)
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{
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ARG_UNUSED(user_data);
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ARG_UNUSED(dev);
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printk("[LVD] Interrupt: Voltage level crossing detected!\n");
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printk("[WARNING] Voltage instability detected! Check power supply.\n");
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k_sem_give(&lvd_sem);
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}
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#endif
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/* Handle voltage status: get, print, update LEDs */
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static void handle_voltage_status(const struct device *lvd_dev, const char *tag)
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{
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int ret;
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renesas_lvd_status_t status;
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ret = renesas_lvd_get_status(lvd_dev, &status);
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if (ret != 0) {
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printk("[%s] Error: Failed to get LVD status.\n", tag);
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return;
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}
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switch (status.position) {
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case RENESAS_LVD_POSITION_ABOVE:
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printk("[%s] Voltage is ABOVE threshold (%.2f V)\n", tag,
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((double)VOLTAGE_THRESHOLD / 100));
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gpio_pin_set_dt(&led_above, 1);
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gpio_pin_set_dt(&led_below, 0);
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break;
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case RENESAS_LVD_POSITION_BELOW:
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printk("[%s] Voltage is BELOW threshold (%.2f V)\n", tag,
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((double)VOLTAGE_THRESHOLD / 100));
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gpio_pin_set_dt(&led_below, 1);
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gpio_pin_set_dt(&led_above, 0);
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break;
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default:
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printk("[%s] Unknown voltage position\n", tag);
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break;
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}
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ret = renesas_lvd_clear_status(lvd_dev);
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if (ret != 0) {
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printk("[%s] Warning: Failed to clear LVD status\n", tag);
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}
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}
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int main(void)
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{
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int ret;
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const struct device *const lvd_dev = DEVICE_DT_GET(LVD_NODE);
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k_sem_init(&lvd_sem, 0, 1);
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if (!device_is_ready(lvd_dev)) {
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printk("[LVD] Error: LVD device not ready.\n");
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return -EINVAL;
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}
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#if LVD_INT
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ret = renesas_lvd_callback_set(lvd_dev, user_callback, NULL);
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if (ret != 0) {
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printk("[LVD] Error: Failed to register callback.\n");
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return -EINVAL;
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}
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#endif
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if (!gpio_is_ready_dt(&led_below) || !gpio_is_ready_dt(&led_above)) {
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printk("[GPIO] Error: LED GPIOs not ready.\n");
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return -ENODEV;
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}
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ret = gpio_pin_configure_dt(&led_below, GPIO_OUTPUT_ACTIVE);
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if (ret < 0) {
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return ret;
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}
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ret = gpio_pin_configure_dt(&led_above, GPIO_OUTPUT_ACTIVE);
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if (ret < 0) {
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return ret;
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}
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printk("===========================================================\n");
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printk("LVD Voltage Monitoring Sample Started\n");
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printk("Threshold Voltage Level : %.2f V\n", ((double)VOLTAGE_THRESHOLD / 100));
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printk("===========================================================\n");
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handle_voltage_status(lvd_dev, "LVD Init");
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while (1) {
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k_sem_take(&lvd_sem, K_FOREVER);
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handle_voltage_status(lvd_dev, "LVD");
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}
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return 0;
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}

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