12-OBD-Speed: settings page with screen rotation (0/90/180/270)

- third tile (swipe left from the menu): rotation buttons, saved in NVS,
  applied at boot
- shared lib: setRotation() rotates only the panel and redraws; touch
  points are converted in touchpad_read() for the current rotation;
  getRotation() added

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

12-OBD-Speed/README.md

@@ -9,6 +9,7 @@ Uses the shared board library and LVGL 9.6 (`../shared`), NimBLE-Arduino 2.5.1.
 - **Swipe left → adapter menu** — scans while open. OBD-like adapters (name OBD/ELM/…, or service FFF0/FFE0/18F0)
   are listed first in green. **Tap one** to select it: it is remembered (NVS) and connected immediately.
   **Forget** clears the remembered adapter, **Done** (or swipe right) returns to the speed page.
+- **Swipe left again → settings** — screen rotation 0 / 90 / 180 / 270 degrees (tap to apply; remembered in NVS, applied at boot).
 - On power-up the remembered adapter is connected automatically; if the link drops or the adapter is not
   there (car off), it retries every 3 s. With no adapter remembered, the device starts on the menu page.
 

12-OBD-Speed/src/main.cpp

@@ -1,6 +1,8 @@
 // OBD speed display for the JC3636W518: vehicle speed from an ELM327 over BLE on top of an animated GIF.
 // Swipe left for the adapter menu (scan, select, forget); the selected adapter is remembered and reconnected.
+// Swipe left again for settings (screen rotation, remembered).
 #include <Arduino.h>
+#include <Preferences.h>
 #include "jc3636w518.h"
 #include "obd_link.h"
 
@@ -19,7 +21,8 @@ static const lv_color_t COLOR_ARC = lv_color_hex(0x00C8FF);
 static const lv_color_t COLOR_OBD = lv_color_hex(0x4CD964);
 static const lv_color_t COLOR_PANEL = lv_color_hex(0x161C22);
 
-static lv_obj_t *tileview, *tile_speed, *tile_menu;
+static lv_obj_t *tileview, *tile_speed, *tile_menu, *tile_settings;
+static lv_obj_t *rot_buttons[4];
 static lv_obj_t *speed_arc, *speed_label, *speed_shadow, *status_label;
 static lv_obj_t *menu_saved, *menu_status, *menu_list;
 static lv_obj_t *menu_items[MAX_MENU_ITEMS];
@@ -79,6 +82,33 @@ static void on_done_clicked(lv_event_t *e)
   show_tile(tile_speed);
 }
 
+// ---------- settings: screen rotation ----------
+static uint8_t load_rotation()
+{
+  Preferences p;
+  p.begin("ui", true);
+  uint8_t r = p.getUChar("rot", 0);
+  p.end();
+  return r > 3 ? 0 : r;
+}
+
+static void highlight_rotation(uint8_t rot)
+{
+  for (int i = 0; i < 4; i++)
+    lv_obj_set_style_bg_color(rot_buttons[i], i == rot ? COLOR_ARC : lv_color_hex(0x222A33), 0);
+}
+
+static void on_rotation_clicked(lv_event_t *e)
+{
+  uint8_t rot = (uint8_t)(intptr_t)lv_event_get_user_data(e);
+  setRotation(rot);
+  highlight_rotation(rot);
+  Preferences p;
+  p.begin("ui", false);
+  p.putUChar("rot", rot);
+  p.end();
+}
+
 // ---------- speed page ----------
 static void build_speed_tile()
 {
@@ -178,6 +208,38 @@ static void build_menu_tile()
   make_button(tile_menu, "Done", 50, 296, 92, on_done_clicked);
 }
 
+static void build_settings_tile()
+{
+  lv_obj_t *title = lv_label_create(tile_settings);
+  lv_obj_set_style_text_font(title, &lv_font_montserrat_20, 0);
+  lv_obj_set_style_text_color(title, COLOR_TEXT, 0);
+  lv_label_set_text(title, "Settings");
+  lv_obj_align(title, LV_ALIGN_TOP_MID, 0, 20);
+
+  lv_obj_t *label = lv_label_create(tile_settings);
+  lv_obj_set_style_text_font(label, &lv_font_montserrat_16, 0);
+  lv_obj_set_style_text_color(label, COLOR_DIM, 0);
+  lv_label_set_text(label, "Screen rotation (degrees)");
+  lv_obj_align(label, LV_ALIGN_TOP_MID, 0, 86);
+
+  static const char *names[4] = {"0", "90", "180", "270"};
+  for (int i = 0; i < 4; i++)
+  {
+    lv_obj_t *b = lv_button_create(tile_settings);
+    lv_obj_set_size(b, 104, 48);
+    lv_obj_align(b, LV_ALIGN_TOP_MID, (i % 2) ? 58 : -58, 118 + (i / 2) * 60);
+    lv_obj_add_event_cb(b, on_rotation_clicked, LV_EVENT_CLICKED, (void *)(intptr_t)i);
+    lv_obj_t *l = lv_label_create(b);
+    lv_label_set_text(l, names[i]);
+    lv_obj_set_style_text_font(l, &lv_font_montserrat_20, 0);
+    lv_obj_center(l);
+    rot_buttons[i] = b;
+  }
+  highlight_rotation(getRotation());
+
+  make_button(tile_settings, "Done", 0, 296, 110, on_done_clicked);
+}
+
 static void build_ui()
 {
   lv_obj_set_style_bg_color(lv_screen_active(), lv_color_hex(0x000000), 0);
@@ -185,10 +247,12 @@ static void build_ui()
   lv_obj_set_style_bg_color(tileview, lv_color_hex(0x000000), 0);
   lv_obj_set_scrollbar_mode(tileview, LV_SCROLLBAR_MODE_OFF);
   tile_speed = lv_tileview_add_tile(tileview, 0, 0, LV_DIR_RIGHT);
-  tile_menu = lv_tileview_add_tile(tileview, 1, 0, LV_DIR_LEFT);
+  tile_menu = lv_tileview_add_tile(tileview, 1, 0, (lv_dir_t)(LV_DIR_LEFT | LV_DIR_RIGHT));
+  tile_settings = lv_tileview_add_tile(tileview, 2, 0, LV_DIR_LEFT);
   lv_obj_add_event_cb(tileview, on_tile_changed, LV_EVENT_VALUE_CHANGED, NULL);
   build_speed_tile();
   build_menu_tile();
+  build_settings_tile();
 }
 
 // ---------- periodic updates ----------
@@ -279,6 +343,7 @@ void setup()
   delay(200);
   Serial.begin(115200);
   scr_lvgl_init();
+  setRotation(load_rotation());
   build_ui();
   obd_begin();
   if (obd_saved_address().length() == 0)