st7735s: Added brightness control though LED pin

-> Uses LED(Backlight) Pin as PWM to control the brightness

Signed-off-by: Rajssss <sssraj.sssraj@gmail.com>

Author: Rajssss

lvgl_tft/st7735s.c

@@ -10,6 +10,7 @@
 #include "disp_spi.h"
 #include "driver/i2c.h"
 #include "driver/gpio.h"
+#include "driver/ledc.h"
 #include "esp_log.h"
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
@@ -172,6 +173,51 @@ void st7735s_sleep_out()
 	st7735s_send_cmd(0x11);
 }
 
+void st7735s_brightness_control_enable(void)
+{
+	/*
+		Configure LED (Backlight) pin as PWM for Brightness control.
+	*/
+    ledc_channel_config_t LCD_backlight_channel = {
+        .gpio_num = ST7735S_BCKL,
+        .speed_mode = LEDC_LOW_SPEED_MODE,
+        .channel = LEDC_CHANNEL_0,
+        .intr_type = LEDC_INTR_DISABLE,
+        .timer_sel = LEDC_TIMER_0,
+        .duty = 0,
+        .hpoint = 0,
+        .flags.output_invert = 0
+    };
+    ledc_timer_config_t LCD_backlight_timer = {
+        .speed_mode = LEDC_LOW_SPEED_MODE,
+        .bit_num = LEDC_TIMER_10_BIT,
+        .timer_num = LEDC_TIMER_0,
+        .freq_hz = 5000,
+        .clk_cfg = LEDC_AUTO_CLK
+    };
+
+	ESP_ERROR_CHECK( ledc_timer_config(&LCD_backlight_timer) );
+	ESP_ERROR_CHECK( ledc_channel_config(&LCD_backlight_channel) );
+
+}
+
+void st7735s_set_brightness(uint16_t brightness)
+{
+	/*
+		Set brightness.
+		0   -> Display off
+		100 -> Full brightness
+		NOTE: brightness value must be between 0 - 100
+	*/
+	if(brightness > 100)
+	{
+		ESP_LOGE(TAG, "Brightness value must be between 0 - 100");
+		return;
+	}
+    ESP_ERROR_CHECK( ledc_set_duty(LEDC_LOW_SPEED_MODE, LEDC_CHANNEL_0, brightness*10) );
+	ESP_ERROR_CHECK( ledc_update_duty(LEDC_LOW_SPEED_MODE, LEDC_CHANNEL_0) );
+}
+
 /**********************
  *   STATIC FUNCTIONS
  **********************/

lvgl_tft/st7735s.h

@@ -26,6 +26,7 @@ extern "C" {
 #define DISP_BUF_SIZE (LV_HOR_RES_MAX * 40)
 
 #define ST7735S_DC       CONFIG_LV_DISP_PIN_DC
+#define ST7735S_BCKL     CONFIG_LV_DISP_PIN_BCKL
 #define ST7735S_RST      CONFIG_LV_DISP_PIN_RST
 #define ST7735S_USE_RST  CONFIG_LV_DISP_USE_RST
 
@@ -137,6 +138,8 @@ void st7735s_flush(lv_disp_drv_t * drv, const lv_area_t * area, lv_color_t * col
 void st7735s_enable_backlight(bool backlight);
 void st7735s_sleep_in(void);
 void st7735s_sleep_out(void);
+void st7735s_brightness_control_enable(void);
+void st7735s_set_brightness(uint16_t brightness);
 
 /**********************
  *      MACROS