Merge branch 'feature/ledc_low_speed_channels' into 'master'

add ledc low speed channels



1. add low speed channels

2. modify example code.



See merge request !490

components/driver/include/driver/ledc.h

@@ -29,8 +29,7 @@ extern "C" {
 
 typedef enum {
     LEDC_HIGH_SPEED_MODE = 0, /*!< LEDC high speed speed_mode */
-    //in this version, we only support high speed speed_mode. We will access low speed speed_mode later
-    //LEDC_LOW_SPEED_MODE,    /*!< LEDC low speed speed_mode */
+    LEDC_LOW_SPEED_MODE,    /*!< LEDC low speed speed_mode */
     LEDC_SPEED_MODE_MAX,      /*!< LEDC speed limit */
 } ledc_mode_t;
 
@@ -137,8 +136,6 @@ esp_err_t ledc_timer_config(ledc_timer_config_t* timer_conf);
  *        After ledc_set_duty, ledc_set_fade, we need to call this function to update the settings.
  *
  * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode,
- *        now we only support high-speed mode.
- *        We will access low-speed mode in next version
  * @param channel LEDC channel(0-7), select from ledc_channel_t
  *
  * @return
@@ -152,7 +149,7 @@ esp_err_t ledc_update_duty(ledc_mode_t speed_mode, ledc_channel_t channel);
  * @brief LEDC stop.
  *        Disable LEDC output, and set idle level
  *
- * @param  speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode, now we only support high-speed mode. We will access low-speed mode in next version
+ * @param  speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode
  * @param  channel LEDC channel(0-7), select from ledc_channel_t
  * @param  idle_level Set output idle level after LEDC stops.
  *
@@ -165,7 +162,7 @@ esp_err_t ledc_stop(ledc_mode_t speed_mode, ledc_channel_t channel, uint32_t idl
 /**
  * @brief LEDC set channel frequency(Hz)
  *
- * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode, now we only support high-speed mode. We will access low-speed mode in next version
+ * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode
  * @param  timer_num LEDC timer index(0-3), select from ledc_timer_t
  * @param  freq_hz Set the LEDC frequency
  *
@@ -179,7 +176,7 @@ esp_err_t ledc_set_freq(ledc_mode_t speed_mode, ledc_timer_t timer_num, uint32_t
 /**
  * @brief      LEDC get channel frequency(Hz)
  *
- * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode, now we only support high-speed mode. We will access low-speed mode in next version
+ * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode
  * @param timer_num LEDC timer index(0-3), select from ledc_timer_t
  *
  * @return
@@ -192,7 +189,7 @@ uint32_t ledc_get_freq(ledc_mode_t speed_mode, ledc_timer_t timer_num);
  * @brief LEDC set duty
  *        Only after calling ledc_update_duty will the duty update.
  *
- * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode, now we only support high-speed mode. We will access low-speed mode in next version
+ * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode
  * @param channel LEDC channel(0-7), select from ledc_channel_t
  * @param duty Set the LEDC duty, the duty range is [0, (2**bit_num) - 1]
  *
@@ -205,7 +202,7 @@ esp_err_t ledc_set_duty(ledc_mode_t speed_mode, ledc_channel_t channel, uint32_t
 /**
  * @brief LEDC get duty
  *
- * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode, now we only support high-speed mode. We will access low-speed mode in next version
+ * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode
  * @param channel LEDC channel(0-7), select from ledc_channel_t
  *
  * @return
@@ -218,7 +215,7 @@ int ledc_get_duty(ledc_mode_t speed_mode, ledc_channel_t channel);
  * @brief LEDC set gradient
  *        Set LEDC gradient, After the function calls the ledc_update_duty function, the function can take effect.
  *
- * @param  speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode, now we only support high-speed mode. We will access low-speed mode in next version
+ * @param  speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode
  * @param  channel LEDC channel(0-7), select from ledc_channel_t
  * @param  duty Set the start of the gradient duty, the duty range is [0, (2**bit_num) - 1]
  * @param  gradule_direction Set the direction of the gradient
@@ -254,7 +251,7 @@ esp_err_t ledc_isr_register(void (*fn)(void*), void * arg, int intr_alloc_flags,
 /**
  * @brief Configure LEDC settings
  *
- * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode, now we only support high-speed mode. We will access low-speed mode in next version
+ * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode
  * @param timer_sel  Timer index(0-3), there are 4 timers in LEDC module
  * @param div_num Timer clock divide number, the timer clock is divided from the selected clock source
  * @param bit_num The count number of one period, counter range is 0 ~ ((2 ** bit_num) - 1)
@@ -269,7 +266,7 @@ esp_err_t ledc_timer_set(ledc_mode_t speed_mode, ledc_timer_t timer_sel, uint32_
 /**
  * @brief Reset LEDC timer
  *
- * @param  speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode, now we only support high-speed mode. We will access low-speed mode in next version
+ * @param  speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode
  * @param  timer_sel LEDC timer index(0-3), select from ledc_timer_t
  *
  * @return
@@ -281,7 +278,7 @@ esp_err_t ledc_timer_rst(ledc_mode_t speed_mode, uint32_t timer_sel);
 /**
  * @brief Pause LEDC timer counter
  *
- * @param  speed_mode  Select the LEDC speed_mode, high-speed mode and low-speed mode, now we only support high-speed mode. We will access low-speed mode in next version
+ * @param  speed_mode  Select the LEDC speed_mode, high-speed mode and low-speed mode
  * @param  timer_sel LEDC timer index(0-3), select from ledc_timer_t
  *
  * @return
@@ -294,7 +291,7 @@ esp_err_t ledc_timer_pause(ledc_mode_t speed_mode, uint32_t timer_sel);
 /**
  * @brief Resume LEDC timer
  *
- * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode, now we only support high-speed mode. We will access low-speed mode in next version
+ * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode
  * @param timer_sel LEDC timer index(0-3), select from ledc_timer_t
  *
  * @return
@@ -306,7 +303,7 @@ esp_err_t ledc_timer_resume(ledc_mode_t speed_mode, uint32_t timer_sel);
 /**
  * @brief Bind LEDC channel with the selected timer
  *
- * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode, now we only support high-speed mode. We will access low-speed mode in next version
+ * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode
  * @param channel LEDC channel index(0-7), select from ledc_channel_t
  * @param timer_idx LEDC timer index(0-3), select from ledc_timer_t
  *
@@ -321,7 +318,6 @@ esp_err_t ledc_bind_channel_timer(ledc_mode_t speed_mode, uint32_t channel, uint
  *        Call ledc_fade_start() after this to start fading.
  *
  * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode,
- *                   For now we only support high-speed mode. We will access low-speed mode soon.
  * @param channel LEDC channel index(0-7), select from ledc_channel_t
  * @param target_duty Target duty of fading.( 0 - (2 ** bit_num - 1)))
  * @param scale Controls the increase or decrease step scale.
@@ -331,6 +327,7 @@ esp_err_t ledc_bind_channel_timer(ledc_mode_t speed_mode, uint32_t channel, uint
  *     - ESP_ERR_INVALID_ARG Parameter error
  *     - ESP_OK Success
  *     - ESP_ERR_INVALID_STATE Fade function not installed.
+ *     - ESP_FAIL Fade function init error
  */
 esp_err_t ledc_set_fade_with_step(ledc_mode_t speed_mode, ledc_channel_t channel, int target_duty, int scale, int cycle_num);
 
@@ -339,7 +336,6 @@ esp_err_t ledc_set_fade_with_step(ledc_mode_t speed_mode, ledc_channel_t channel
  *        Call ledc_fade_start() after this to start fading.
  *
  * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode,
- *                   For now we only support high-speed mode. We will access low-speed mode soon.
  * @param channel LEDC channel index(0-7), select from ledc_channel_t
  * @param target_duty Target duty of fading.( 0 - (2 ** bit_num - 1)))
  * @param max_fade_time_ms The maximum time of the fading ( ms ).
@@ -348,6 +344,7 @@ esp_err_t ledc_set_fade_with_step(ledc_mode_t speed_mode, ledc_channel_t channel
  *     - ESP_ERR_INVALID_ARG Parameter error
  *     - ESP_OK Success
  *     - ESP_ERR_INVALID_STATE Fade function not installed.
+ *     - ESP_FAIL Fade function init error
  */
 esp_err_t ledc_set_fade_with_time(ledc_mode_t speed_mode, ledc_channel_t channel, int target_duty, int max_fade_time_ms);
 
@@ -358,7 +355,6 @@ esp_err_t ledc_set_fade_with_time(ledc_mode_t speed_mode, ledc_channel_t channel
  *        ESP_INTR_FLAG_* values. See esp_intr_alloc.h for more info.
  *
  * @return
- *     - ESP_ERR_NO_MEM No enough memory
  *     - ESP_OK Success
  *     - ESP_ERR_INVALID_STATE Fade function already installed.
  */
@@ -373,6 +369,7 @@ void ledc_fade_func_uninstall();
 /**
  * @brief Start LEDC fading.
  *
+ * @param speed_mode Select the LEDC speed_mode, high-speed mode and low-speed mode
  * @param channel LEDC channel number
  * @param wait_done Whether to block until fading done.
  *
@@ -381,7 +378,7 @@ void ledc_fade_func_uninstall();
  *     - ESP_ERR_INVALID_STATE Fade function not installed.
  *     - ESP_ERR_INVALID_ARG Parameter error.
  */
-esp_err_t ledc_fade_start(ledc_channel_t channel, ledc_fade_mode_t wait_done);
+esp_err_t ledc_fade_start(ledc_mode_t speed_mode, ledc_channel_t channel, ledc_fade_mode_t wait_done);
 
 #ifdef __cplusplus
 }

components/driver/ledc.c

@@ -41,7 +41,8 @@ typedef struct {
     xSemaphoreHandle ledc_fade_sem;
     xSemaphoreHandle ledc_fade_mux;
 } ledc_fade_t;
-static ledc_fade_t* s_ledc_fade_rec = NULL;
+
+static ledc_fade_t *s_ledc_fade_rec[LEDC_SPEED_MODE_MAX][LEDC_CHANNEL_MAX];
 static ledc_isr_handle_t s_ledc_fade_isr_handle = NULL;
 
 #define LEDC_VAL_NO_CHANGE   (-1)
@@ -57,9 +58,24 @@ static ledc_isr_handle_t s_ledc_fade_isr_handle = NULL;
 #define LEDC_FADE_TARGET_ERR_STR    "LEDC fade target duty error"
 #define LEDC_FADE_INSTALLED_ERR_STR  "LEDC fade service already installed"
 #define LEDC_FADE_MODE_ERR_STR       "LEDC fade mode error"
+#define LEDC_FADE_INIT_ERROR_STR     "LEDC fade channel init error"
 
+static void ledc_ls_timer_update(ledc_mode_t speed_mode, ledc_timer_t timer_sel)
+{
+    if (speed_mode == LEDC_LOW_SPEED_MODE) {
+        LEDC.timer_group[speed_mode].timer[timer_sel].conf.low_speed_update = 1;
+    }
+}
 
-esp_err_t ledc_timer_set(ledc_mode_t speed_mode, ledc_timer_t timer_sel, uint32_t div_num, uint32_t bit_num, ledc_clk_src_t clk_src)
+static IRAM_ATTR void ledc_ls_channel_update(ledc_mode_t speed_mode, ledc_channel_t channel_num)
+{
+    if (speed_mode == LEDC_LOW_SPEED_MODE) {
+        LEDC.channel_group[speed_mode].channel[channel_num].conf0.low_speed_update = 1;
+    }
+}
+
+esp_err_t ledc_timer_set(ledc_mode_t speed_mode, ledc_timer_t timer_sel, uint32_t div_num, uint32_t bit_num,
+        ledc_clk_src_t clk_src)
 {
     LEDC_CHECK(speed_mode < LEDC_SPEED_MODE_MAX, LEDC_MODE_ERR_STR, ESP_ERR_INVALID_ARG);
     LEDC_CHECK(timer_sel <= LEDC_TIMER_3, LEDC_TIMER_ERR_STR, ESP_ERR_INVALID_ARG);
@@ -67,9 +83,7 @@ esp_err_t ledc_timer_set(ledc_mode_t speed_mode, ledc_timer_t timer_sel, uint32_
     LEDC.timer_group[speed_mode].timer[timer_sel].conf.div_num = div_num;
     LEDC.timer_group[speed_mode].timer[timer_sel].conf.tick_sel = clk_src;
     LEDC.timer_group[speed_mode].timer[timer_sel].conf.bit_num = bit_num;
-    if (speed_mode != LEDC_HIGH_SPEED_MODE) {
-        LEDC.timer_group[speed_mode].timer[timer_sel].conf.low_speed_update = 1;
-    }
+    ledc_ls_timer_update(speed_mode, timer_sel);
     portEXIT_CRITICAL(&ledc_spinlock);
     return ESP_OK;
 }
@@ -86,6 +100,7 @@ static IRAM_ATTR esp_err_t ledc_duty_config(ledc_mode_t speed_mode, ledc_channel
                                                                     ((duty_num & LEDC_DUTY_NUM_HSCH0_V) << LEDC_DUTY_NUM_HSCH0_S) |
                                                                     ((duty_cycle & LEDC_DUTY_CYCLE_HSCH0_V) << LEDC_DUTY_CYCLE_HSCH0_S) |
                                                                     ((duty_scale & LEDC_DUTY_SCALE_HSCH0_V) << LEDC_DUTY_SCALE_HSCH0_S);
+    ledc_ls_channel_update(speed_mode, channel_num);
     portEXIT_CRITICAL(&ledc_spinlock);
     return ESP_OK;
 }
@@ -96,6 +111,7 @@ esp_err_t ledc_bind_channel_timer(ledc_mode_t speed_mode, ledc_channel_t channel
     LEDC_CHECK(timer_idx <= LEDC_TIMER_3, LEDC_TIMER_ERR_STR, ESP_ERR_INVALID_ARG);
     portENTER_CRITICAL(&ledc_spinlock);
     LEDC.channel_group[speed_mode].channel[channel].conf0.timer_sel = timer_idx;
+    ledc_ls_channel_update(speed_mode, channel);
     portEXIT_CRITICAL(&ledc_spinlock);
     return ESP_OK;
 }
@@ -107,6 +123,7 @@ esp_err_t ledc_timer_rst(ledc_mode_t speed_mode, uint32_t timer_sel)
     portENTER_CRITICAL(&ledc_spinlock);
     LEDC.timer_group[speed_mode].timer[timer_sel].conf.rst = 1;
     LEDC.timer_group[speed_mode].timer[timer_sel].conf.rst = 0;
+    ledc_ls_timer_update(speed_mode, timer_sel);
     portEXIT_CRITICAL(&ledc_spinlock);
     return ESP_OK;
 }
@@ -117,6 +134,7 @@ esp_err_t ledc_timer_pause(ledc_mode_t speed_mode, uint32_t timer_sel)
     LEDC_CHECK(timer_sel <= LEDC_TIMER_3, LEDC_TIMER_ERR_STR, ESP_ERR_INVALID_ARG);
     portENTER_CRITICAL(&ledc_spinlock);
     LEDC.timer_group[speed_mode].timer[timer_sel].conf.pause = 1;
+    ledc_ls_timer_update(speed_mode, timer_sel);
     portEXIT_CRITICAL(&ledc_spinlock);
     return ESP_OK;
 }
@@ -127,6 +145,7 @@ esp_err_t ledc_timer_resume(ledc_mode_t speed_mode, uint32_t timer_sel)
     LEDC_CHECK(timer_sel <= LEDC_TIMER_3, LEDC_TIMER_ERR_STR, ESP_ERR_INVALID_ARG);
     portENTER_CRITICAL(&ledc_spinlock);
     LEDC.timer_group[speed_mode].timer[timer_sel].conf.pause = 0;
+    ledc_ls_timer_update(speed_mode, timer_sel);
     portEXIT_CRITICAL(&ledc_spinlock);
     return ESP_OK;
 }
@@ -138,10 +157,14 @@ static esp_err_t ledc_enable_intr_type(ledc_mode_t speed_mode, uint32_t channel,
     uint32_t intr_type = type;
     portENTER_CRITICAL(&ledc_spinlock);
     value = LEDC.int_ena.val;
+    uint8_t int_en_base = LEDC_DUTY_CHNG_END_HSCH0_INT_ENA_S;
+    if (speed_mode == LEDC_LOW_SPEED_MODE) {
+        int_en_base = LEDC_DUTY_CHNG_END_LSCH0_INT_ENA_S;
+    }
     if (intr_type == LEDC_INTR_FADE_END) {
-        LEDC.int_ena.val = value | BIT(LEDC_DUTY_CHNG_END_HSCH0_INT_ENA_S + channel);
+        LEDC.int_ena.val = value | BIT(int_en_base + channel);
     } else {
-        LEDC.int_ena.val = ( value & ( ~( BIT(LEDC_DUTY_CHNG_END_HSCH0_INT_ENA_S + channel) ) ) );
+        LEDC.int_ena.val = (value & (~(BIT(int_en_base + channel))));
     }
     portEXIT_CRITICAL(&ledc_spinlock);
     return ESP_OK;
@@ -188,12 +211,17 @@ esp_err_t ledc_timer_config(ledc_timer_config_t* timer_conf)
     if (div_param > LEDC_DIV_NUM_HSTIMER0_V) {
         // APB_CLK results in divisor which too high. Try using REF_TICK as clock source.
         timer_clk_src = LEDC_REF_TICK;
-        div_param = ( (uint64_t) LEDC_REF_CLK_HZ << 8 ) / freq_hz / precision;
+        div_param = ((uint64_t) LEDC_REF_CLK_HZ << 8) / freq_hz / precision;
         if (div_param < 256 || div_param > LEDC_DIV_NUM_HSTIMER0_V) {
             ESP_LOGE(LEDC_TAG, "requested frequency and bit depth can not be achieved, try increasing freq_hz or bit_num. div_param=%d",
                 (uint32_t ) div_param);
             ret = ESP_FAIL;
         }
+    } else {
+        if (speed_mode == LEDC_LOW_SPEED_MODE) {
+            //for now, we only select 80mhz for slow clk of LEDC low speed channels.
+            LEDC.conf.slow_clk_sel = 1;
+        }
     }
     // set timer parameters
     ledc_timer_set(speed_mode, timer_num, div_param, bit_num, timer_clk_src);
@@ -212,8 +240,7 @@ esp_err_t ledc_set_pin(int gpio_num, ledc_mode_t speed_mode, ledc_channel_t ledc
     if (speed_mode == LEDC_HIGH_SPEED_MODE) {
         gpio_matrix_out(gpio_num, LEDC_HS_SIG_OUT0_IDX + ledc_channel, 0, 0);
     } else {
-        ESP_LOGE(LEDC_TAG, "low speed mode is not implemented");
-        return ESP_ERR_NOT_SUPPORTED;
+        gpio_matrix_out(gpio_num, LEDC_LS_SIG_OUT0_IDX + ledc_channel, 0, 0);
     }
     return ESP_OK;
 }
@@ -248,7 +275,11 @@ esp_err_t ledc_channel_config(ledc_channel_config_t* ledc_conf)
     /*set LEDC signal in gpio matrix*/
     PIN_FUNC_SELECT(GPIO_PIN_MUX_REG[gpio_num], PIN_FUNC_GPIO);
     gpio_set_direction(gpio_num, GPIO_MODE_OUTPUT);
-    gpio_matrix_out(gpio_num, LEDC_HS_SIG_OUT0_IDX + ledc_channel, 0, 0);
+    if (speed_mode == LEDC_HIGH_SPEED_MODE) {
+        gpio_matrix_out(gpio_num, LEDC_HS_SIG_OUT0_IDX + ledc_channel, 0, 0);
+    } else {
+        gpio_matrix_out(gpio_num, LEDC_LS_SIG_OUT0_IDX + ledc_channel, 0, 0);
+    }
     return ret;
 }
 
@@ -259,6 +290,7 @@ esp_err_t ledc_update_duty(ledc_mode_t speed_mode, ledc_channel_t channel)
     portENTER_CRITICAL(&ledc_spinlock);
     LEDC.channel_group[speed_mode].channel[channel].conf0.sig_out_en = 1;
     LEDC.channel_group[speed_mode].channel[channel].conf1.duty_start = 1;
+    ledc_ls_channel_update(speed_mode, channel);
     portEXIT_CRITICAL(&ledc_spinlock);
     return ESP_OK;
 }
@@ -271,6 +303,7 @@ esp_err_t ledc_stop(ledc_mode_t speed_mode, ledc_channel_t channel, uint32_t idl
     LEDC.channel_group[speed_mode].channel[channel].conf0.idle_lv = idle_level & 0x1;
     LEDC.channel_group[speed_mode].channel[channel].conf0.sig_out_en = 0;
     LEDC.channel_group[speed_mode].channel[channel].conf1.duty_start = 0;
+    ledc_ls_channel_update(speed_mode, channel);
     portEXIT_CRITICAL(&ledc_spinlock);
     return ESP_OK;
 }
@@ -285,7 +318,7 @@ esp_err_t ledc_set_fade(ledc_mode_t speed_mode, ledc_channel_t channel, uint32_t
         ESP_LOGE(LEDC_TAG, "step_num=%u duty_cyle_num=%u duty_scale=%u", step_num, duty_cyle_num, duty_scale);
         return ESP_ERR_INVALID_ARG;
     }
-    if (s_ledc_fade_rec) {
+    if (s_ledc_fade_rec[speed_mode][channel]) {
         ledc_enable_intr_type(speed_mode, channel, LEDC_INTR_DISABLE);
     }
     ledc_duty_config(speed_mode,
@@ -304,7 +337,7 @@ esp_err_t ledc_set_duty(ledc_mode_t speed_mode, ledc_channel_t channel, uint32_t
 {
     LEDC_CHECK(speed_mode < LEDC_SPEED_MODE_MAX, LEDC_MODE_ERR_STR, ESP_ERR_INVALID_ARG);
     LEDC_CHECK(channel <= LEDC_CHANNEL_7, LEDC_CHANNEL_ERR_STR, ESP_ERR_INVALID_ARG);
-    if (s_ledc_fade_rec) {
+    if (s_ledc_fade_rec[speed_mode][channel]) {
         ledc_enable_intr_type(speed_mode, channel, LEDC_INTR_DISABLE);
     }
     ledc_duty_config(speed_mode,
@@ -334,11 +367,11 @@ esp_err_t ledc_set_freq(ledc_mode_t speed_mode, ledc_timer_t timer_num, uint32_t
     uint32_t div_num = 0;
     uint32_t bit_num = LEDC.timer_group[speed_mode].timer[timer_num].conf.bit_num;
     uint32_t timer_source_clk = LEDC.timer_group[speed_mode].timer[timer_num].conf.tick_sel;
-    uint32_t precision = ( 0x1 << bit_num );
+    uint32_t precision = (0x1 << bit_num);
     if (timer_source_clk == LEDC_APB_CLK) {
-        div_num = ( (uint64_t) LEDC_APB_CLK_HZ << 8 ) / freq_hz / precision;
+        div_num = ((uint64_t) LEDC_APB_CLK_HZ << 8) / freq_hz / precision;
     } else {
-        div_num = ( (uint64_t) LEDC_REF_CLK_HZ << 8 ) / freq_hz / precision;
+        div_num = ((uint64_t) LEDC_REF_CLK_HZ << 8) / freq_hz / precision;
     }
     if (div_num <= 256 || div_num > LEDC_DIV_NUM_HSTIMER0) {
         ESP_LOGE(LEDC_TAG, "div param err,div_param=%u", div_num);
@@ -351,81 +384,127 @@ esp_err_t ledc_set_freq(ledc_mode_t speed_mode, ledc_timer_t timer_num, uint32_t
 
 uint32_t ledc_get_freq(ledc_mode_t speed_mode, ledc_timer_t timer_num)
 {
-    LEDC_CHECK(speed_mode < LEDC_SPEED_MODE_MAX, LEDC_MODE_ERR_STR, ( 0 ));
+    LEDC_CHECK(speed_mode < LEDC_SPEED_MODE_MAX, LEDC_MODE_ERR_STR, (0));
     portENTER_CRITICAL(&ledc_spinlock);
     uint32_t freq = 0;
     uint32_t timer_source_clk = LEDC.timer_group[speed_mode].timer[timer_num].conf.tick_sel;
     uint32_t bit_num = LEDC.timer_group[speed_mode].timer[timer_num].conf.bit_num;
     uint32_t div_num = LEDC.timer_group[speed_mode].timer[timer_num].conf.div_num;
-    uint32_t precision = ( 0x1 << bit_num );
+    uint32_t precision = (0x1 << bit_num);
     if (timer_source_clk == LEDC_APB_CLK) {
-        freq = ( (uint64_t) LEDC_APB_CLK_HZ << 8 ) / precision / div_num;
+        freq = ((uint64_t) LEDC_APB_CLK_HZ << 8) / precision / div_num;
     } else {
-        freq = ( (uint64_t) LEDC_REF_CLK_HZ << 8 ) / precision / div_num;
+        freq = ((uint64_t) LEDC_REF_CLK_HZ << 8) / precision / div_num;
     }
     portEXIT_CRITICAL(&ledc_spinlock);
     return freq;
 }
 
-void IRAM_ATTR ledc_fade_isr()
+void IRAM_ATTR ledc_fade_isr(void* arg)
 {
-    int i;
+    int channel;
     portBASE_TYPE HPTaskAwoken = pdFALSE;
     uint32_t intr_status = LEDC.int_st.val;  //read LEDC interrupt status.
     LEDC.int_clr.val = intr_status;  //clear LEDC interrupt status.
-    for (i = 0; i < 8; i++) {
-        if (intr_status & BIT(LEDC_DUTY_CHNG_END_HSCH0_INT_ST_S + i)) {
-            int speed_mode = s_ledc_fade_rec[i].speed_mode;
-            int duty_cur = LEDC.channel_group[speed_mode].channel[i].duty_rd.duty_read >> LEDC_DUTY_DECIMAL_BIT_NUM;
-            if (duty_cur == s_ledc_fade_rec[i].target_duty) {
-                if(s_ledc_fade_rec[i].mode == LEDC_FADE_WAIT_DONE) {
-                    xSemaphoreGiveFromISR(s_ledc_fade_rec[i].ledc_fade_sem, &HPTaskAwoken);
-                    if(HPTaskAwoken == pdTRUE) {
-                        portYIELD_FROM_ISR() ;
+    int speed_mode = LEDC_HIGH_SPEED_MODE;
+    for (channel = 0; channel < LEDC_CHANNEL_MAX; channel++) {
+        if (intr_status & (BIT(LEDC_DUTY_CHNG_END_HSCH0_INT_ST_S + channel) | BIT(LEDC_DUTY_CHNG_END_LSCH0_INT_ST_S + channel))) {
+            if (intr_status & BIT(LEDC_DUTY_CHNG_END_HSCH0_INT_ST_S + channel)) {
+                speed_mode = LEDC_HIGH_SPEED_MODE;
+            } else {
+                speed_mode = LEDC_LOW_SPEED_MODE;
+            }
+            if (s_ledc_fade_rec[speed_mode][channel] == NULL) {
+                //fade object not initialized yet.
+                continue;
+            }
+            int duty_cur = LEDC.channel_group[speed_mode].channel[channel].duty_rd.duty_read >> LEDC_DUTY_DECIMAL_BIT_NUM;
+            if (duty_cur == s_ledc_fade_rec[speed_mode][channel]->target_duty) {
+                if (s_ledc_fade_rec[speed_mode][channel]->mode == LEDC_FADE_WAIT_DONE) {
+                    xSemaphoreGiveFromISR(s_ledc_fade_rec[speed_mode][channel]->ledc_fade_sem, &HPTaskAwoken);
+                    if (HPTaskAwoken == pdTRUE) {
+                        portYIELD_FROM_ISR();
                     }
                 }
                 continue;
             }
-            int duty_tar = s_ledc_fade_rec[i].target_duty;
-            int scale = s_ledc_fade_rec[i].scale;
+            int duty_tar = s_ledc_fade_rec[speed_mode][channel]->target_duty;
+            int scale = s_ledc_fade_rec[speed_mode][channel]->scale;
             if (scale == 0) {
                 continue;
             }
-            int cycle = s_ledc_fade_rec[i].cycle_num;
-            int delta = s_ledc_fade_rec[i].direction == LEDC_DUTY_DIR_DECREASE ? duty_cur - duty_tar : duty_tar - duty_cur;
+            int cycle = s_ledc_fade_rec[speed_mode][channel]->cycle_num;
+            int delta = s_ledc_fade_rec[speed_mode][channel]->direction == LEDC_DUTY_DIR_DECREASE ? duty_cur - duty_tar : duty_tar - duty_cur;
             int step = delta / scale > LEDC_STEP_NUM_MAX ? LEDC_STEP_NUM_MAX : delta / scale;
-
             if (delta > scale) {
                 ledc_duty_config(
                     speed_mode,
-                    i,
+                    channel,
                     LEDC_VAL_NO_CHANGE,
                     duty_cur << LEDC_DUTY_DECIMAL_BIT_NUM,
-                    s_ledc_fade_rec[i].direction,
+                    s_ledc_fade_rec[speed_mode][channel]->direction,
                     step,
                     cycle,
                     scale);
             } else {
                 ledc_duty_config(
                     speed_mode,
-                    i,
+                    channel,
                     LEDC_VAL_NO_CHANGE,
                     duty_tar << LEDC_DUTY_DECIMAL_BIT_NUM,
-                    s_ledc_fade_rec[i].direction,
+                    s_ledc_fade_rec[speed_mode][channel]->direction,
                     1,
                     1,
                     0);
             }
-            LEDC.channel_group[speed_mode].channel[i].conf1.duty_start = 1;
+            LEDC.channel_group[speed_mode].channel[channel].conf1.duty_start = 1;
         }
     }
     LEDC.int_clr.val = intr_status;  //clear LEDC interrupt status.
 }
 
+static esp_err_t ledc_fade_channel_deinit(ledc_mode_t speed_mode, ledc_channel_t channel)
+{
+    if (s_ledc_fade_rec[speed_mode][channel]) {
+        if (s_ledc_fade_rec[speed_mode][channel]->ledc_fade_mux) {
+            vSemaphoreDelete(s_ledc_fade_rec[speed_mode][channel]->ledc_fade_mux);
+            s_ledc_fade_rec[speed_mode][channel]->ledc_fade_mux = NULL;
+        }
+        if (s_ledc_fade_rec[speed_mode][channel]->ledc_fade_sem) {
+            vSemaphoreDelete(s_ledc_fade_rec[speed_mode][channel]->ledc_fade_sem);
+            s_ledc_fade_rec[speed_mode][channel]->ledc_fade_sem = NULL;
+        }
+        free(s_ledc_fade_rec[speed_mode][channel]);
+        s_ledc_fade_rec[speed_mode][channel] = NULL;
+    }
+    return ESP_OK;
+}
+
+static esp_err_t ledc_fade_channel_init_check(ledc_mode_t speed_mode, ledc_channel_t channel)
+{
+    if (s_ledc_fade_rec[speed_mode][channel] == NULL) {
+        s_ledc_fade_rec[speed_mode][channel] = (ledc_fade_t *) calloc(1, sizeof(ledc_fade_t));
+        s_ledc_fade_rec[speed_mode][channel]->ledc_fade_mux = xSemaphoreCreateMutex();
+        s_ledc_fade_rec[speed_mode][channel]->ledc_fade_sem = xSemaphoreCreateBinary();
+    }
+    if (s_ledc_fade_rec[speed_mode][channel]
+        && s_ledc_fade_rec[speed_mode][channel]->ledc_fade_mux
+        && s_ledc_fade_rec[speed_mode][channel]->ledc_fade_sem) {
+        return ESP_OK;
+    } else {
+        ledc_fade_channel_deinit(speed_mode, channel);
+        return ESP_FAIL;
+    }
+}
+
 esp_err_t ledc_set_fade_with_time(ledc_mode_t speed_mode, ledc_channel_t channel, int target_duty, int max_fade_time_ms)
 {
+    LEDC_CHECK(speed_mode < LEDC_SPEED_MODE_MAX, LEDC_MODE_ERR_STR, ESP_ERR_INVALID_ARG);
+    LEDC_CHECK(channel < LEDC_CHANNEL_MAX, LEDC_CHANNEL_ERR_STR, ESP_ERR_INVALID_ARG);
+    LEDC_CHECK(ledc_fade_channel_init_check(speed_mode, channel) == ESP_OK , LEDC_FADE_INIT_ERROR_STR, ESP_FAIL);
+
     int timer_sel = LEDC.channel_group[speed_mode].channel[channel].conf0.timer_sel;
-    int max_duty = ( 1 << ( LEDC.timer_group[speed_mode].timer[timer_sel].conf.bit_num ) ) - 1;
+    int max_duty = (1 << (LEDC.timer_group[speed_mode].timer[timer_sel].conf.bit_num)) - 1;
     LEDC_CHECK(target_duty <= max_duty, LEDC_FADE_TARGET_ERR_STR, ESP_ERR_INVALID_ARG);
     uint32_t freq = ledc_get_freq(speed_mode, timer_sel);
     int duty_cur = LEDC.channel_group[speed_mode].channel[channel].duty_rd.duty_read >> LEDC_DUTY_DECIMAL_BIT_NUM;
@@ -441,16 +520,17 @@ esp_err_t ledc_set_fade_with_time(ledc_mode_t speed_mode, ledc_channel_t channel
         cycle_num = total_cycles / duty_delta;
     } else {
         cycle_num = 1;
-        scale = ( duty_delta + total_cycles - 1 ) / total_cycles;
+        scale = (duty_delta + total_cycles - 1) / total_cycles;
     }
     return ledc_set_fade_with_step(speed_mode, channel, target_duty, scale, cycle_num);
 }
 
 esp_err_t ledc_set_fade_with_step(ledc_mode_t speed_mode, ledc_channel_t channel, int target_duty, int scale, int cycle_num)
 {
-    LEDC_CHECK(s_ledc_fade_rec != NULL, LEDC_FADE_SERVICE_ERR_STR, ESP_ERR_INVALID_STATE);
     LEDC_CHECK(speed_mode < LEDC_SPEED_MODE_MAX, LEDC_MODE_ERR_STR, ESP_ERR_INVALID_ARG);
     LEDC_CHECK(channel < LEDC_CHANNEL_MAX, LEDC_CHANNEL_ERR_STR, ESP_ERR_INVALID_ARG);
+    LEDC_CHECK(ledc_fade_channel_init_check(speed_mode, channel) == ESP_OK , LEDC_FADE_INIT_ERROR_STR, ESP_FAIL);
+
     int timer_sel = LEDC.channel_group[speed_mode].channel[channel].conf0.timer_sel;
     int max_duty = (1 << (LEDC.timer_group[speed_mode].timer[timer_sel].conf.bit_num)) - 1;
     LEDC_CHECK(target_duty <= max_duty, LEDC_FADE_TARGET_ERR_STR, ESP_ERR_INVALID_ARG);
@@ -463,18 +543,18 @@ esp_err_t ledc_set_fade_with_step(ledc_mode_t speed_mode, ledc_channel_t channel
     if (duty_delta == 0) {
         return ESP_OK;
     }
-    s_ledc_fade_rec[channel].speed_mode = speed_mode;
-    s_ledc_fade_rec[channel].target_duty = target_duty;
-    s_ledc_fade_rec[channel].cycle_num = cycle_num;
-    s_ledc_fade_rec[channel].scale = scale;
+    s_ledc_fade_rec[speed_mode][channel]->speed_mode = speed_mode;
+    s_ledc_fade_rec[speed_mode][channel]->target_duty = target_duty;
+    s_ledc_fade_rec[speed_mode][channel]->cycle_num = cycle_num;
+    s_ledc_fade_rec[speed_mode][channel]->scale = scale;
     int step_num;
     if (duty_cur > target_duty) {
-        s_ledc_fade_rec[channel].direction = LEDC_DUTY_DIR_DECREASE;
-        step_num = ( duty_cur - target_duty ) / scale;
+        s_ledc_fade_rec[speed_mode][channel]->direction = LEDC_DUTY_DIR_DECREASE;
+        step_num = (duty_cur - target_duty) / scale;
         step_num = step_num > LEDC_STEP_NUM_MAX ? LEDC_STEP_NUM_MAX : step_num;
     } else {
-        s_ledc_fade_rec[channel].direction = LEDC_DUTY_DIR_INCREASE;
-        step_num = ( target_duty - duty_cur ) / scale;
+        s_ledc_fade_rec[speed_mode][channel]->direction = LEDC_DUTY_DIR_INCREASE;
+        step_num = (target_duty - duty_cur) / scale;
         step_num = step_num > LEDC_STEP_NUM_MAX ? LEDC_STEP_NUM_MAX : step_num;
     }
     portEXIT_CRITICAL(&ledc_spinlock);
@@ -483,42 +563,28 @@ esp_err_t ledc_set_fade_with_step(ledc_mode_t speed_mode, ledc_channel_t channel
         speed_mode,
         channel,
         duty_cur,
-        s_ledc_fade_rec[channel].direction,
+        s_ledc_fade_rec[speed_mode][channel]->direction,
         step_num,
-        s_ledc_fade_rec[channel].cycle_num,
-        s_ledc_fade_rec[channel].scale
+        s_ledc_fade_rec[speed_mode][channel]->cycle_num,
+        s_ledc_fade_rec[speed_mode][channel]->scale
         );
     ESP_LOGD(LEDC_TAG, "cur duty: %d; target: %d, step: %d, cycle: %d; scale: %d\n",
         LEDC.channel_group[speed_mode].channel[channel].duty_rd.duty_read >> LEDC_DUTY_DECIMAL_BIT_NUM,
         target_duty,
         step_num,
-        s_ledc_fade_rec[channel].cycle_num,
-        s_ledc_fade_rec[channel].scale
+        s_ledc_fade_rec[speed_mode][channel]->cycle_num,
+        s_ledc_fade_rec[speed_mode][channel]->scale
         );
-    LEDC.int_clr.val |= BIT(LEDC_DUTY_CHNG_END_HSCH0_INT_ENA_S + channel);
+    int bit_num_ch0 = (speed_mode == LEDC_HIGH_SPEED_MODE) ? LEDC_DUTY_CHNG_END_HSCH0_INT_ENA_S : LEDC_DUTY_CHNG_END_LSCH0_INT_ENA_S;
+    LEDC.int_clr.val |= BIT(bit_num_ch0 + channel);
     ledc_enable_intr_type(speed_mode, channel, LEDC_INTR_FADE_END);
     return ESP_OK;
 }
 
 esp_err_t ledc_fade_func_install(int intr_alloc_flags)
 {
-    LEDC_CHECK(s_ledc_fade_rec == NULL, LEDC_FADE_INSTALLED_ERR_STR, ESP_ERR_INVALID_STATE);
-    s_ledc_fade_rec = (ledc_fade_t*) calloc(LEDC_CHANNEL_MAX, sizeof(ledc_fade_t));
-    if (s_ledc_fade_rec == NULL) {
-        return ESP_ERR_NO_MEM;
-    }
-    int i = 0;
-    for (i = 0; i < LEDC_CHANNEL_MAX; i++) {
-        s_ledc_fade_rec[i].ledc_fade_sem = xSemaphoreCreateBinary();
-        s_ledc_fade_rec[i].ledc_fade_mux = xSemaphoreCreateMutex();
-        if (s_ledc_fade_rec[i].ledc_fade_sem == NULL || s_ledc_fade_rec[i].ledc_fade_mux == NULL) {
-            ledc_fade_func_uninstall();
-            return ESP_ERR_NO_MEM;
-        }
-    }
     //OR intr_alloc_flags with ESP_INTR_FLAG_IRAM because the fade isr is in IRAM
-    ledc_isr_register(ledc_fade_isr, NULL, intr_alloc_flags | ESP_INTR_FLAG_IRAM, &s_ledc_fade_isr_handle);
-    return ESP_OK;
+    return ledc_isr_register(ledc_fade_isr, NULL, intr_alloc_flags | ESP_INTR_FLAG_IRAM, &s_ledc_fade_isr_handle);
 }
 
 void ledc_fade_func_uninstall()
@@ -526,42 +592,32 @@ void ledc_fade_func_uninstall()
     if (s_ledc_fade_rec == NULL) {
         return;
     }
-    if(s_ledc_fade_isr_handle) {
+    if (s_ledc_fade_isr_handle) {
         esp_intr_free(s_ledc_fade_isr_handle);
         s_ledc_fade_isr_handle = NULL;
     }
-    int i;
-    for (i = 0; i < LEDC_CHANNEL_MAX; i++) {
-        if (s_ledc_fade_rec[i].ledc_fade_sem) {
-            xSemaphoreHandle sem_tmp = s_ledc_fade_rec[i].ledc_fade_sem;
-            s_ledc_fade_rec[i].ledc_fade_sem = NULL;
-            vSemaphoreDelete(sem_tmp);
-        }
-        if (s_ledc_fade_rec[i].ledc_fade_mux) {
-            xSemaphoreHandle mux_tmp = s_ledc_fade_rec[i].ledc_fade_mux;
-            s_ledc_fade_rec[i].ledc_fade_mux = NULL;
-            vSemaphoreDelete(mux_tmp);
+    int channel, mode;
+    for (mode = 0; mode < LEDC_SPEED_MODE_MAX; mode++) {
+        for (channel = 0; channel < LEDC_CHANNEL_MAX; channel++) {
+            ledc_fade_channel_deinit(mode, channel);
         }
     }
-    free(s_ledc_fade_rec);
-    s_ledc_fade_rec = NULL;
     return;
 }
 
-esp_err_t ledc_fade_start(ledc_channel_t channel, ledc_fade_mode_t wait_done)
+esp_err_t ledc_fade_start(ledc_mode_t speed_mode, ledc_channel_t channel, ledc_fade_mode_t wait_done)
 {
     LEDC_CHECK(s_ledc_fade_rec != NULL, LEDC_FADE_SERVICE_ERR_STR, ESP_ERR_INVALID_STATE);
     LEDC_CHECK(wait_done < LEDC_FADE_MAX, LEDC_FADE_MODE_ERR_STR, ESP_ERR_INVALID_ARG);
-    int speed_mode = s_ledc_fade_rec[channel].speed_mode;
-    xSemaphoreTake(s_ledc_fade_rec[channel].ledc_fade_mux, portMAX_DELAY);
+    xSemaphoreTake(s_ledc_fade_rec[speed_mode][channel]->ledc_fade_mux, portMAX_DELAY);
     if (wait_done == LEDC_FADE_WAIT_DONE) {
-        s_ledc_fade_rec[channel].mode = LEDC_FADE_WAIT_DONE;
+        s_ledc_fade_rec[speed_mode][channel]->mode = LEDC_FADE_WAIT_DONE;
         ledc_update_duty(speed_mode, channel);
-        xSemaphoreTake(s_ledc_fade_rec[channel].ledc_fade_sem, portMAX_DELAY);
+        xSemaphoreTake(s_ledc_fade_rec[speed_mode][channel]->ledc_fade_sem, portMAX_DELAY);
     } else {
-        s_ledc_fade_rec[channel].mode = LEDC_FADE_NO_WAIT;
+        s_ledc_fade_rec[speed_mode][channel]->mode = LEDC_FADE_NO_WAIT;
         ledc_update_duty(speed_mode, channel);
     }
-    xSemaphoreGive(s_ledc_fade_rec[channel].ledc_fade_mux);
+    xSemaphoreGive(s_ledc_fade_rec[speed_mode][channel]->ledc_fade_mux);
     return ESP_OK;
 }

components/esp32/include/soc/ledc_struct.h

@@ -21,7 +21,8 @@ typedef volatile struct {
                     uint32_t timer_sel:  2;              /*There are four high speed timers  the two bits are used to select one of them for high speed channel.  2'b00: seletc hstimer0.   2'b01: select hstimer1.  2'b10: select hstimer2.    2'b11: select hstimer3.*/
                     uint32_t sig_out_en: 1;              /*This is the output enable control bit for high speed channel*/
                     uint32_t idle_lv:    1;              /*This bit is used to control the output value when high speed channel is off.*/
-                    uint32_t reserved4: 27;
+                    uint32_t low_speed_update: 1;        /*This bit is only useful for low speed timer channels, reserved for high speed timers*/
+                    uint32_t reserved4: 26;
                     uint32_t clk_en:     1;              /*This bit is clock gating control signal. when software configure LED_PWM internal registers  it controls the register clock.*/
                 };
                 uint32_t val;
@@ -204,9 +205,13 @@ typedef volatile struct {
     } int_clr;
     union {
         struct {
-            uint32_t apb_clk_sel: 1;                   /*This bit is used to set the frequency of slow_clk. 1'b1:80mhz  1'b0:8mhz*/
+            uint32_t apb_clk_sel: 1;                   /*This bit decides the slow clock for LEDC low speed channels, so we want to replace the field name with slow_clk_sel*/
             uint32_t reserved1:  31;
         };
+        struct {
+            uint32_t slow_clk_sel: 1;                  /*This bit is used to set the frequency of slow_clk. 1'b1:80mhz  1'b0:8mhz, (only used by LEDC low speed channels/timers)*/
+            uint32_t reserved:  31;
+        };
         uint32_t val;
     } conf;
     uint32_t reserved_194;

examples/peripherals/ledc/README.md

@@ -14,3 +14,4 @@
  
  * This example use GPIO18/19/4/5 as LEDC ouput, and it will change the duty repeatedly.
 
+ * GPIO18/19 are from high speed channel group. GPIO4/5 are from low speed channel group.

examples/peripherals/ledc/main/ledc_fade.c

@@ -27,105 +27,124 @@
  *
  * 4. This example use GPIO18/19/4/5 as LEDC ouput, and it will change the duty repeatedly.
  *
+ * 5. GPIO18/19 are from high speed channel group. GPIO4/5 are from low speed channel group.
  *
  */
+#define LEDC_HS_TIMER          LEDC_TIMER_0
+#define LEDC_HS_MODE           LEDC_HIGH_SPEED_MODE
+#define LEDC_HS_CH0_GPIO       (18)
+#define LEDC_HS_CH0_CHANNEL    LEDC_CHANNEL_0
+#define LEDC_HS_CH1_GPIO       (19)
+#define LEDC_HS_CH1_CHANNEL    LEDC_CHANNEL_1
 
-#define LEDC_IO_0    (18)
-#define LEDC_IO_1    (19)
-#define LEDC_IO_2    (4)
-#define LEDC_IO_3    (5)
+#define LEDC_LS_TIMER          LEDC_TIMER_1
+#define LEDC_LS_MODE           LEDC_LOW_SPEED_MODE
+#define LEDC_LS_CH2_GPIO       (4)
+#define LEDC_LS_CH2_CHANNEL    LEDC_CHANNEL_2
+#define LEDC_LS_CH3_GPIO       (5)
+#define LEDC_LS_CH3_CHANNEL    LEDC_CHANNEL_3
+
+#define LEDC_TEST_CH_NUM       (4)
+typedef struct {
+    int channel;
+    int io;
+    int mode;
+    int timer_idx;
+} ledc_info_t;
+
+void app_main()
+{
+    int ch;
+    ledc_info_t ledc_ch[LEDC_TEST_CH_NUM] = {
+        {
+            .channel   = LEDC_HS_CH0_CHANNEL,
+            .io        = LEDC_HS_CH0_GPIO,
+            .mode      = LEDC_HS_MODE,
+            .timer_idx = LEDC_HS_TIMER
+        },
+        {
+            .channel   = LEDC_HS_CH1_CHANNEL,
+            .io        = LEDC_HS_CH1_GPIO,
+            .mode      = LEDC_HS_MODE,
+            .timer_idx = LEDC_HS_TIMER
+        },
+        {
+            .channel   = LEDC_LS_CH2_CHANNEL,
+            .io        = LEDC_LS_CH2_GPIO,
+            .mode      = LEDC_LS_MODE,
+            .timer_idx = LEDC_LS_TIMER
+        },
+        {
+            .channel   = LEDC_LS_CH3_CHANNEL,
+            .io        = LEDC_LS_CH3_GPIO,
+            .mode      = LEDC_LS_MODE,
+            .timer_idx = LEDC_LS_TIMER
+        }
+    };
 
-esp_err_t app_main() 
-{	
     ledc_timer_config_t ledc_timer = {
-        //set timer counter bit number
-        .bit_num = LEDC_TIMER_13_BIT,
-        //set frequency of pwm
-        .freq_hz = 5000,
-        //timer mode,
-        .speed_mode = LEDC_HIGH_SPEED_MODE,
-        //timer index
-        .timer_num = LEDC_TIMER_0
+        .bit_num = LEDC_TIMER_13_BIT, //set timer counter bit number
+        .freq_hz = 5000,              //set frequency of pwm
+        .speed_mode = LEDC_HS_MODE,   //timer mode,
+        .timer_num = LEDC_HS_TIMER    //timer index
     };
+    //configure timer0 for high speed channels
     ledc_timer_config(&ledc_timer);
 
-    ledc_channel_config_t ledc_channel = {
-        //set LEDC channel 0
-        .channel = LEDC_CHANNEL_0,
-        //set the duty for initialization.(duty range is 0 ~ ((2**bit_num)-1)
-        .duty = 100,
-        //GPIO number
-        .gpio_num = LEDC_IO_0,
-        //GPIO INTR TYPE, as an example, we enable fade_end interrupt here.
-        .intr_type = LEDC_INTR_FADE_END,
-        //set LEDC mode, from ledc_mode_t
-        .speed_mode = LEDC_HIGH_SPEED_MODE,
-        //set LEDC timer source, if different channel use one timer,
-        //the frequency and bit_num of these channels should be the same
-        .timer_sel = LEDC_TIMER_0
-    };
-    //set the configuration
-    ledc_channel_config(&ledc_channel);
+    //configure timer1 for low speed channels
+    ledc_timer.speed_mode = LEDC_LS_MODE;
+    ledc_timer.timer_num = LEDC_LS_TIMER;
+    ledc_timer_config(&ledc_timer);
 
-    //config ledc channel1
-    ledc_channel.channel = LEDC_CHANNEL_1;
-    ledc_channel.gpio_num = LEDC_IO_1;
-    ledc_channel_config(&ledc_channel);
-    //config ledc channel2
-    ledc_channel.channel = LEDC_CHANNEL_2;
-    ledc_channel.gpio_num = LEDC_IO_2;
-    ledc_channel_config(&ledc_channel);
-    //config ledc channel3
-    ledc_channel.channel = LEDC_CHANNEL_3;
-    ledc_channel.gpio_num = LEDC_IO_3;
-    ledc_channel_config(&ledc_channel);
+    for (ch = 0; ch < LEDC_TEST_CH_NUM; ch++) {
+        ledc_channel_config_t ledc_channel = {
+            //set LEDC channel 0
+            .channel = ledc_ch[ch].channel,
+            //set the duty for initialization.(duty range is 0 ~ ((2**bit_num)-1)
+            .duty = 0,
+            //GPIO number
+            .gpio_num = ledc_ch[ch].io,
+            //GPIO INTR TYPE, as an example, we enable fade_end interrupt here.
+            .intr_type = LEDC_INTR_FADE_END,
+            //set LEDC mode, from ledc_mode_t
+            .speed_mode = ledc_ch[ch].mode,
+            //set LEDC timer source, if different channel use one timer,
+            //the frequency and bit_num of these channels should be the same
+            .timer_sel = ledc_ch[ch].timer_idx,
+        };
+        //set the configuration
+        ledc_channel_config(&ledc_channel);
+    }
 
     //initialize fade service.
     ledc_fade_func_install(0);
-
-    while(1) {
+    while (1) {
         printf("LEDC fade up\n");
-        ledc_set_fade_with_time(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_0, 1000, 2000);
-        ledc_set_fade_with_time(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_1, 7000, 2000);
-        ledc_set_fade_with_time(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_2, 5000, 2000);
-        ledc_set_fade_with_time(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_3, 3000, 2000);
-        ledc_fade_start(LEDC_CHANNEL_0, LEDC_FADE_NO_WAIT);
-        ledc_fade_start(LEDC_CHANNEL_1, LEDC_FADE_NO_WAIT);
-        ledc_fade_start(LEDC_CHANNEL_2, LEDC_FADE_NO_WAIT);
-        ledc_fade_start(LEDC_CHANNEL_3, LEDC_FADE_NO_WAIT);
+        for (ch = 0; ch < LEDC_TEST_CH_NUM; ch++) {
+            ledc_set_fade_with_time(ledc_ch[ch].mode, ledc_ch[ch].channel, 4000, 2000);
+            ledc_fade_start(ledc_ch[ch].mode, ledc_ch[ch].channel, LEDC_FADE_NO_WAIT);
+        }
         vTaskDelay(3000 / portTICK_PERIOD_MS);
 
         printf("LEDC fade down\n");
-        ledc_set_fade_with_time(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_0, 100, 2000);
-        ledc_set_fade_with_time(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_1, 300, 2000);
-        ledc_set_fade_with_time(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_2, 500, 2000);
-        ledc_set_fade_with_time(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_3, 700, 2000);
-        ledc_fade_start(LEDC_CHANNEL_0, LEDC_FADE_NO_WAIT);
-        ledc_fade_start(LEDC_CHANNEL_1, LEDC_FADE_NO_WAIT);
-        ledc_fade_start(LEDC_CHANNEL_2, LEDC_FADE_NO_WAIT);
-        ledc_fade_start(LEDC_CHANNEL_3, LEDC_FADE_NO_WAIT);
+        for (ch = 0; ch < LEDC_TEST_CH_NUM; ch++) {
+            ledc_set_fade_with_time(ledc_ch[ch].mode, ledc_ch[ch].channel, 0, 2000);
+            ledc_fade_start(ledc_ch[ch].mode, ledc_ch[ch].channel, LEDC_FADE_NO_WAIT);
+        }
         vTaskDelay(3000 / portTICK_PERIOD_MS);
 
         printf("LEDC set duty without fade\n");
-        ledc_set_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_0, 1000);
-        ledc_set_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_1, 7000);
-        ledc_set_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_2, 5000);
-        ledc_set_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_3, 3000);
-        ledc_update_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_0);
-        ledc_update_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_1);
-        ledc_update_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_2);
-        ledc_update_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_3);
-        vTaskDelay(2000 / portTICK_PERIOD_MS);
+        for (ch = 0; ch < LEDC_TEST_CH_NUM; ch++) {
+            ledc_set_duty(ledc_ch[ch].mode, ledc_ch[ch].channel, 2000);
+            ledc_update_duty(ledc_ch[ch].mode, ledc_ch[ch].channel);
+        }
+        vTaskDelay(1000 / portTICK_PERIOD_MS);
 
         printf("LEDC set duty without fade\n");
-        ledc_set_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_0, 0);
-        ledc_set_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_1, 0);
-        ledc_set_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_2, 0);
-        ledc_set_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_3, 0);
-        ledc_update_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_0);
-        ledc_update_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_1);
-        ledc_update_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_2);
-        ledc_update_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_3);
-        vTaskDelay(2000 / portTICK_PERIOD_MS);
+        for (ch = 0; ch < LEDC_TEST_CH_NUM; ch++) {
+            ledc_set_duty(ledc_ch[ch].mode, ledc_ch[ch].channel, 0);
+            ledc_update_duty(ledc_ch[ch].mode, ledc_ch[ch].channel);
+        }
+        vTaskDelay(1000 / portTICK_PERIOD_MS);
     }
 }