fix 3.5 backlight and GT911 for cyd_35r.

TFT_BL was wrongly GPIO21 (GT911 INT); use GPIO27, DRAW_BUF_DIV=20, and export firmware/cyd_35r.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/main.cpp

@@ -0,0 +1,45 @@
+#include <Arduino.h>
+#include <lvgl.h>
+
+#include "pins.h"
+#include "touch.h"
+#include "wifi_prov.h"
+#include "wifi_ui.h"
+
+static constexpr uint32_t DRAW_BUF_SIZE =
+    (SCREEN_WIDTH * SCREEN_HEIGHT / DRAW_BUF_DIV * (LV_COLOR_DEPTH / 8));
+static uint32_t draw_buf[DRAW_BUF_SIZE / 4];
+
+void setup() {
+  Serial.begin(460800);
+  delay(200);
+  Serial.println();
+  Serial.printf("LVGL %d.%d.%d | CYD WiFi Prov\n", lv_version_major(),
+                lv_version_minor(), lv_version_patch());
+
+  pinMode(TFT_BL_PIN, OUTPUT);
+  digitalWrite(TFT_BL_PIN, HIGH);
+
+  touch_init();
+
+  lv_init();
+  lv_display_t *disp =
+      lv_tft_espi_create(SCREEN_WIDTH, SCREEN_HEIGHT, draw_buf, sizeof(draw_buf));
+  lv_display_set_rotation(disp, LV_DISPLAY_ROTATION_270);
+
+  lv_indev_t *indev = lv_indev_create();
+  lv_indev_set_type(indev, LV_INDEV_TYPE_POINTER);
+  lv_indev_set_read_cb(indev, touch_read_cb);
+  lv_indev_set_display(indev, disp);
+
+  wifi_prov_begin();
+  wifi_ui_create();
+}
+
+void loop() {
+  wifi_prov_loop();
+  wifi_ui_tick();
+  lv_timer_handler();
+  lv_tick_inc(5);
+  delay(5);
+}