ledc_fade.c
The H2 LEDC ramps by itself: ledc_set_fade_with_time computes the steps and the hardware applies the ramp while the CPU sleeps. Two calls per cycle for a 0-100% round trip in 1 s.
Hardware required
An ESP32-H2 board (RISC-V 96 MHz, IEEE 802.15.4 radio only — no Wi-Fi) such as a DevKitM-1, powered over USB. 1 LED + 330 Ω resistor on GPIO8 (or the user LED).
Wiring
LED anode on GPIO8 through 330 Ω, cathode GND. Any pin routable to the low-speed LEDC works.
How it works
An LEDC timer sets frequency (5 kHz) and resolution (10 bits); the channel carries the duty cycle. fade_start without wait launches the ramp the peripheral unwinds with no CPU task. Program it with ESP-IDF (idf.py set-target esp32h2); the USB-Serial/JTAG port (GPIO26/27) acts as console and flash port. Hold Boot + Reset for download mode if needed.
Going further
Two channels on the R and B pins of an RGB LED for a color gradient, or sync the ramp with the 802.15.4 radio.
ledc_fade.c
// ledc_fade.c — rampe automatique du LEDC (hardware fade).
#include "driver/ledc.h"
#include "esp_log.h"
#define CANAL LEDC_CHANNEL_0
#define PIN GPIO_NUM_8
static const char *TAG = "fade";
void app_main(void)
{
ledc_timer_config_t timer = {
.speed_mode = LEDC_LOW_SPEED_MODE, .duty_resolution = 10,
.timer_num = LEDC_TIMER_0, .freq_hz = 5000, .clk_cfg = LEDC_AUTO_CLK,
};
ESP_ERROR_CHECK(ledc_timer_config(&timer));
ledc_channel_config_t ch = {
.channel = CANAL, .duty = 0, .gpio_num = PIN,
.speed_mode = LEDC_LOW_SPEED_MODE, .timer_sel = LEDC_TIMER_0,
};
ESP_ERROR_CHECK(ledc_channel_config(&ch));
ledc_fade_func_install(0);
while (1) {
ESP_LOGI(TAG, "montee");
ledc_set_fade_with_time(LEDC_LOW_SPEED_MODE, CANAL, 1023, 1000);
ledc_fade_start(LEDC_LOW_SPEED_MODE, CANAL, LEDC_FADE_NO_WAIT);
vTaskDelay(pdMS_TO_TICKS(1100));
ESP_LOGI(TAG, "descente");
ledc_set_fade_with_time(LEDC_LOW_SPEED_MODE, CANAL, 0, 1000);
ledc_fade_start(LEDC_LOW_SPEED_MODE, CANAL, LEDC_FADE_NO_WAIT);
vTaskDelay(pdMS_TO_TICKS(1100));
}
}