feature(ledc):add ledc about esp8266

examples/peripherals/ledc/main/ledc_example_main.c

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+// Copyright 2018-2025 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "freertos/FreeRTOS.h"
+#include "freertos/queue.h"
+#include "freertos/task.h"
+
+#include "esp_err.h"
+#include "esp_log.h"
+
+#include "driver/ledc.h"
+
+#define LEDC_HS_CH0_GPIO (13)
+#define LEDC_HS_CH1_GPIO (14)
+#define LEDC_LS_CH2_GPIO (15)
+#define LEDC_LS_CH3_GPIO (12)
+
+#define LEDC_HS_CH0_CHANNEL LEDC_CHANNEL_0
+#define LEDC_HS_CH1_CHANNEL LEDC_CHANNEL_1
+#define LEDC_LS_CH2_CHANNEL LEDC_CHANNEL_2
+#define LEDC_LS_CH3_CHANNEL LEDC_CHANNEL_3
+
+#define LEDC_TEST_CH_NUM (4)
+#define LEDC_TEST_FREQ (1000) //1KHz
+#define LEDC_TEST_DUTY (900) //duty = LEDC_TEST_DUTY / LEDC_TEST_PERIOD  & LEDC_TEST_PERIOD = 1,000,000 / LEDC_TEST_FREQ
+#define LEDC_TEST_FADE_TIME (3000)
+
+static const char* TAG = "main";
+
+void app_main()
+{
+    int ch;
+    /*
+     * Prepare and set configuration of timers
+     * that will be used by LED Controller
+     */
+
+    ledc_timer_config_t ledc_timer = {
+        .duty_resolution = LEDC_TIMER_1_BIT, // resolution of PWM duty(Invalid parameter, compatible with esp32 API)
+        .freq_hz = LEDC_TEST_FREQ, // frequency of PWM signal
+        .speed_mode = 0, // timer mode (Invalid parameter, compatible with esp32 API)
+        .timer_num = 0 // timer index (Invalid parameter, compatible with esp32 API)
+    };
+    // Set configuration of timer0 for high speed channels
+    ledc_timer_config(&ledc_timer);
+
+    /*
+     * Prepare individual configuration
+     * for each channel of LED Controller
+     * by selecting:
+     * - controller's channel number
+     * - output duty cycle, set initially to 0
+     * - GPIO number where LED is connected to
+     * - speed mode, either high or low
+     * - timer servicing selected channel
+     *   Note: Speed_mode and timer_sel are only compatible with esp32, 
+     *   but it is not required in esp8266, so it can be set to 0 when
+     *   using esp8266
+     */
+    ledc_channel_config_t ledc_channel[LEDC_TEST_CH_NUM] = {
+        { .channel = LEDC_HS_CH0_CHANNEL,
+            .duty = 0,
+            .gpio_num = LEDC_HS_CH0_GPIO,
+            .speed_mode = 0,
+            .timer_sel = 0 },
+        { .channel = LEDC_HS_CH1_CHANNEL,
+            .duty = 0,
+            .gpio_num = LEDC_HS_CH1_GPIO,
+            .speed_mode = 0,
+            .timer_sel = 0 },
+        { .channel = LEDC_LS_CH2_CHANNEL,
+            .duty = 0,
+            .gpio_num = LEDC_LS_CH2_GPIO,
+            .speed_mode = 0,
+            .timer_sel = 0 },
+        { .channel = LEDC_LS_CH3_CHANNEL,
+            .duty = 0,
+            .gpio_num = LEDC_LS_CH3_GPIO,
+            .speed_mode = 0,
+            .timer_sel = 0 },
+    };
+
+    // Set LED Controller with previously prepared configuration
+    for (ch = 0; ch < LEDC_TEST_CH_NUM; ch++) {
+        ledc_channel_config(&ledc_channel[ch]);
+    }
+
+    // Initialize fade service.
+    ledc_fade_func_install(0);
+
+    while (1) {
+        ESP_LOGI(TAG, "1. LEDC fade up to duty = %d\n", LEDC_TEST_DUTY);
+        for (ch = 0; ch < LEDC_TEST_CH_NUM; ch++) {
+            ledc_set_fade_with_time(ledc_channel[ch].speed_mode,
+                ledc_channel[ch].channel, LEDC_TEST_DUTY, LEDC_TEST_FADE_TIME);
+        }
+        for (ch = 0; ch < LEDC_TEST_CH_NUM; ch++) {
+            ledc_fade_start(ledc_channel[ch].speed_mode,
+                ledc_channel[ch].channel, LEDC_FADE_NO_WAIT);
+        }
+        vTaskDelay(LEDC_TEST_FADE_TIME / portTICK_PERIOD_MS);
+        vTaskDelay(LEDC_TEST_FADE_TIME / portTICK_PERIOD_MS);
+
+        ESP_LOGI(TAG, "2. LEDC fade down to duty = 0\n");
+        for (ch = 0; ch < LEDC_TEST_CH_NUM; ch++) {
+            ledc_set_fade_with_time(ledc_channel[ch].speed_mode,
+                ledc_channel[ch].channel, 0, LEDC_TEST_FADE_TIME);
+        }
+        for (ch = 0; ch < LEDC_TEST_CH_NUM; ch++) {
+            ledc_fade_start(ledc_channel[ch].speed_mode,
+                ledc_channel[ch].channel, LEDC_FADE_NO_WAIT);
+        }
+        vTaskDelay(LEDC_TEST_FADE_TIME / portTICK_PERIOD_MS);
+        vTaskDelay(LEDC_TEST_FADE_TIME / portTICK_PERIOD_MS);
+    }
+}