feat(mipi_dsi): measure FPS by toggling GPIO

examples/peripherals/lcd/mipi_dsi/README.md

@@ -50,6 +50,8 @@ Before testing your LCD, you also need to read your LCD spec carefully, and then
 Run `idf.py menuconfig` and go to `Example Configuration`:
 
 * Choose whether to `Use DMA2D to copy draw buffer to frame buffer` asynchronously. If you choose `No`, the draw buffer will be copied to the frame buffer synchronously by CPU.
+* Choose if you want to `Monitor FPS by GPIO`. If you choose `Yes`, then you can attach an oscilloscope or logic analyzer to the GPIO pin to monitor the FPS of the display.
+  Please note, the actual FPS should be **double** the square wave frequency.
 
 ### Build and Flash
 

examples/peripherals/lcd/mipi_dsi/main/Kconfig.projbuild

@@ -5,4 +5,11 @@ menu "Example Configuration"
         help
             Enable this option, DMA2D will be used to copy the LVGL draw buffer to the target frame buffer.
             This can save some CPU time and improve the performance.
+
+    config EXAMPLE_MONITOR_FPS_BY_GPIO
+        bool "Monitor FPS by GPIO"
+        default y
+        help
+            Enable this option, you can visualize the FPS by attaching a logic analyzer to a specific GPIO.
+            The GPIO will output a square wave with the frequency of FPS/2.
 endmenu

examples/peripherals/lcd/mipi_dsi/main/mipi_dsi_lcd_example_main.c

@@ -51,6 +51,10 @@ static const char *TAG = "example";
 #define EXAMPLE_PIN_NUM_BK_LIGHT                -1
 #define EXAMPLE_PIN_NUM_LCD_RST                 -1
 
+#if CONFIG_EXAMPLE_MONITOR_FPS_BY_GPIO
+#define EXAMPLE_PIN_NUM_FPS_MONITOR             20  // Monitor the FPS by toggling the GPIO
+#endif
+
 ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 //////////////////// Please update the following configuration according to your Application ///////////////////////////
 ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -123,6 +127,17 @@ static bool example_notify_lvgl_flush_ready(esp_lcd_panel_handle_t panel, esp_lc
     return false;
 }
 
+#if CONFIG_EXAMPLE_MONITOR_FPS_BY_GPIO
+static bool example_monitor_fps(esp_lcd_panel_handle_t panel, esp_lcd_dpi_panel_event_data_t *edata, void *user_ctx)
+{
+    static int io_level = 0;
+    // please note, the real FPS should be 2*frequency of this GPIO toggling
+    gpio_set_level(EXAMPLE_PIN_NUM_FPS_MONITOR, io_level);
+    io_level = !io_level;
+    return false;
+}
+#endif
+
 static void example_bsp_enable_dsi_phy_power(void)
 {
     // Turn on the power for MIPI DSI PHY, so it can go from "No Power" state to "Shutdown" state
@@ -155,8 +170,23 @@ static void example_bsp_set_lcd_backlight(uint32_t level)
 #endif
 }
 
+#if CONFIG_EXAMPLE_MONITOR_FPS_BY_GPIO
+static void example_bsp_init_fps_monitor_io(void)
+{
+    gpio_config_t monitor_io_conf = {
+        .mode = GPIO_MODE_OUTPUT,
+        .pin_bit_mask = 1ULL << EXAMPLE_PIN_NUM_FPS_MONITOR,
+    };
+    ESP_ERROR_CHECK(gpio_config(&monitor_io_conf));
+}
+#endif
+
 void app_main(void)
 {
+#if CONFIG_EXAMPLE_MONITOR_FPS_BY_GPIO
+    example_bsp_init_fps_monitor_io();
+#endif
+
     example_bsp_enable_dsi_phy_power();
     example_bsp_init_lcd_backlight();
     example_bsp_set_lcd_backlight(EXAMPLE_LCD_BK_LIGHT_OFF_LEVEL);
@@ -246,6 +276,9 @@ void app_main(void)
     ESP_LOGI(TAG, "Register DPI panel event callback for LVGL flush ready notification");
     esp_lcd_dpi_panel_event_callbacks_t cbs = {
         .on_color_trans_done = example_notify_lvgl_flush_ready,
+#if CONFIG_EXAMPLE_MONITOR_FPS_BY_GPIO
+        .on_refresh_done = example_monitor_fps,
+#endif
     };
     ESP_ERROR_CHECK(esp_lcd_dpi_panel_register_event_callbacks(mipi_dpi_panel, &cbs, display));