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pre-calculated brightness table

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This commit is contained in:
Drath Vader
2026-03-16 01:08:28 +01:00
parent bd91ece2de
commit e8e97c0e6b
1 changed files with 30 additions and 14 deletions
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44
main/light_driver.c
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@@ -6,19 +6,25 @@
#include "esp_log.h"
#include "esp_err.h"
#include <stdbool.h>
#include <math.h>
static const char* TAG = "light_driver";
static const uint8_t light_gpio = 15;
static const uint16_t light_pwm_freq = 20000;
static const ledc_channel_t light_ledc_channel = LEDC_CHANNEL_0;
static const ledc_mode_t light_ledc_mode = LEDC_LOW_SPEED_MODE;
/* tweakable stuff */
static const uint8_t light_gpio = 2;
static const uint16_t light_pwm_freq = 65000;
static const ledc_timer_bit_t light_pwm_resolution = LEDC_TIMER_10_BIT;
static const uint32_t light_max_brightness = (1 << light_pwm_resolution) - 1;
static const uint32_t light_max_level = 254; // zigbee light level, goes from 0 to 254
static const double light_lowest_duty_pct = 0.05; // lowest duty percentage where the LEDs still light up nice
/* no need to tweak this stuff */
static const ledc_channel_t light_ledc_channel = LEDC_CHANNEL_0;
static const ledc_mode_t light_ledc_speed_mode = LEDC_LOW_SPEED_MODE;
static const uint32_t light_brightness_steps = (1 << light_pwm_resolution) - 1;
/* global vars */
static bool light_init_done = false;
static uint8_t light_current_level = 0;
static uint16_t gamma_lut[ZIGBEE_LIGHT_LEVELS + 1];
esp_err_t light_driver_set_level(const uint8_t level, const uint16_t transition_ms) {
if (!light_init_done) {
@@ -27,12 +33,11 @@ esp_err_t light_driver_set_level(const uint8_t level, const uint16_t transition_
}
light_current_level = level;
double brightness = (double)light_current_level / (double)light_max_level;
if (brightness > 1) brightness = 1;
if (brightness < 0) brightness = 0;
const uint32_t duty = (uint32_t)(light_max_brightness * brightness * brightness); // brightness^2 for fast gamma correction
ESP_ERROR_CHECK(ledc_set_fade_with_time(light_ledc_mode, light_ledc_channel, duty, transition_ms));
ESP_ERROR_CHECK(ledc_fade_start(light_ledc_mode, light_ledc_channel, LEDC_FADE_NO_WAIT));
const uint16_t duty = gamma_lut[light_current_level];
ESP_ERROR_CHECK(ledc_fade_stop(light_ledc_speed_mode, light_ledc_channel));
ESP_ERROR_CHECK(ledc_set_fade_with_time(light_ledc_speed_mode, light_ledc_channel, duty, transition_ms));
ESP_ERROR_CHECK(ledc_fade_start(light_ledc_speed_mode, light_ledc_channel, LEDC_FADE_NO_WAIT));
ESP_LOGI(TAG, "led set to %d, max is %d", duty, light_brightness_steps);
return ESP_OK;
}
@@ -42,7 +47,7 @@ esp_err_t light_driver_set_power(const bool power, const uint16_t transition_ms)
esp_err_t light_driver_init(const bool default_state) {
const ledc_timer_config_t ledc_timer = {
.speed_mode = light_ledc_mode,
.speed_mode = light_ledc_speed_mode,
.duty_resolution = light_pwm_resolution,
.timer_num = LEDC_TIMER_2,
.freq_hz = light_pwm_freq,
@@ -57,10 +62,21 @@ esp_err_t light_driver_init(const bool default_state) {
.duty = 0, // Set duty to 0%
.hpoint = 0
};
for (uint8_t i = 0; i <= ZIGBEE_LIGHT_LEVELS; i++) {
const double brightness_pct = (double)i / (double)ZIGBEE_LIGHT_LEVELS;
const double gamma_corrected = pow(brightness_pct, 2.2);
const double scaled = (double)light_brightness_steps * gamma_corrected * (1 - light_lowest_duty_pct);
gamma_lut[i] = (uint16_t)scaled + (uint16_t)((double)light_brightness_steps * light_lowest_duty_pct) + 1;
}
gamma_lut[0] = 0; // 0 is always completely off
if (gamma_lut[ZIGBEE_LIGHT_LEVELS] > light_brightness_steps) gamma_lut[ZIGBEE_LIGHT_LEVELS] = light_brightness_steps;
ESP_LOGI(TAG, "pre-computed brightness lookup table");
ESP_ERROR_CHECK(ledc_timer_config(&ledc_timer));
ESP_ERROR_CHECK(ledc_channel_config(&ledc_channel));
ESP_ERROR_CHECK(ledc_fade_func_install(0));
ESP_LOGI(TAG, "light driver inited, f=%d Hz", light_pwm_freq);
ESP_LOGI(TAG, "ledc driver initialized, f=%d Hz, %d step resolution", light_pwm_freq, light_brightness_steps);
light_init_done = true;
light_driver_set_power(default_state, 100);
return ESP_OK;