diff --git a/firmware/export_from_build.ps1 b/firmware/export_from_build.ps1
index 24244ee..71cff14 100644
--- a/firmware/export_from_build.ps1
+++ b/firmware/export_from_build.ps1
@@ -1,9 +1,13 @@
-# Rebuild (optional) and refresh firmware/cyd from PlatformIO build output.
-# Usage:
-#   .\firmware\export_from_build.ps1
-#   .\firmware\export_from_build.ps1 -SkipBuild
+# Export firmware bins from PlatformIO build.
+# Default: 2.8" (cyd -> firmware/cyd)
+# 3.5":    .\firmware\export_from_build.ps1 -Env cyd_35r
+#          (only after: pio run -e cyd_35r)
 
-param([switch]$SkipBuild)
+param(
+  [switch]$SkipBuild,
+  [ValidateSet("cyd", "cyd_35r")]
+  [string]$Env = "cyd"
+)
 
 $ErrorActionPreference = "Stop"
 $root = Split-Path -Parent (Split-Path -Parent $MyInvocation.MyCommand.Path)
@@ -12,17 +16,26 @@ Set-Location $root
 $env:Path = "C:\Users\dsx2016\AppData\Local\Programs\Python\Python312\Scripts;" + $env:Path
 
 if (-not $SkipBuild) {
-  pio run -e cyd
+  pio run -e $Env
   if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
 }
 
-$src = Join-Path $root ".pio\build\cyd"
-$dst = Join-Path $root "firmware\cyd"
+$src = Join-Path $root (".pio\build\" + $Env)
+if ($Env -eq "cyd_35r") {
+  $dstName = "cyd_35r"
+  $boardLine = "board: ESP32-3248S035 (ST7796)"
+  $boardIdHint = "esp32-3248s035"
+} else {
+  $dstName = "cyd"
+  $boardLine = "board: ESP32-2432S028R (ILI9341)"
+  $boardIdHint = "esp32-2432s028"
+}
+$dst = Join-Path $root ("firmware\" + $dstName)
 New-Item -ItemType Directory -Force -Path $dst | Out-Null
 
 foreach ($f in @("bootloader.bin", "partitions.bin", "firmware.bin")) {
   $p = Join-Path $src $f
-  if (-not (Test-Path $p)) { Write-Error "Missing build artifact: $p" }
+  if (-not (Test-Path $p)) { Write-Error "Missing build artifact: $p — build with: pio run -e $Env" }
   Copy-Item $p $dst -Force
 }
 
@@ -37,11 +50,10 @@ try { $git = (git -C $root rev-parse --short HEAD).Trim() } catch { $git = "unkn
 $date = Get-Date -Format "yyyy-MM-dd"
 $hashes = Get-ChildItem (Join-Path $dst "*.bin") | Get-FileHash -Algorithm SHA256
 $lines = @(
-  "name: CYD Button (cyd)",
+  "name: CYD btntest ($dstName)",
   "git: $git",
   "date: $date",
-  "board: ESP32-2432S028R (ILI9341)",
-  "features: SoftSPI touch, LVGL, 3-pin button OUT on GPIO22 count+1",
+  $boardLine,
   "flash_size: 4MB",
   "offsets:",
   "  0x1000  bootloader.bin",
@@ -54,4 +66,22 @@ foreach ($h in $hashes) {
   $lines += ("  {0,-15} {1}" -f (Split-Path $h.Path -Leaf), $h.Hash)
 }
 $lines | Set-Content -Encoding utf8 (Join-Path $dst "VERSION.txt")
-Write-Host "Exported -> $dst (git $git)"
+
+# Keep / refresh meta.json boardId for catalog filtering
+$metaPath = Join-Path $dst "meta.json"
+if (Test-Path $metaPath) {
+  try {
+    $meta = Get-Content $metaPath -Raw | ConvertFrom-Json
+    $meta.boardId = $boardIdHint
+    if ($Env -eq "cyd_35r" -and $meta.name -notmatch "3\.5") {
+      $meta.name = ($meta.name -replace "\s*$","") + " (3.5\")"
+    }
+    $meta | ConvertTo-Json -Depth 8 | Set-Content -Encoding utf8 $metaPath
+  } catch {
+    Write-Host "meta.json update skipped: $_"
+  }
+} elseif ($Env -eq "cyd_35r") {
+  Write-Host "Note: add firmware/cyd_35r/meta.json with boardId=$boardIdHint for the web catalog"
+}
+
+Write-Host "Exported -> $dst (env=$Env git=$git)"
diff --git a/include/pins.h b/include/pins.h
index 86af0f4..c56e924 100644
--- a/include/pins.h
+++ b/include/pins.h
@@ -1,8 +1,20 @@
 #pragma once
 
-// CYD ESP32-2432S028R — 触控/屏脚与 tftest 一致
+// Board pins — 2.8" default; 3.5" when CYD_BOARD_3248S035 is set (env:cyd_35r)
 
+#if defined(CYD_BOARD_3248S035)
+#define TFT_BL_PIN 27
+#define SCREEN_WIDTH  320
+#define SCREEN_HEIGHT 480
+#define UI_HOR_RES    480
+#define UI_VER_RES    320
+#else
 #define TFT_BL_PIN 21
+#define SCREEN_WIDTH  240
+#define SCREEN_HEIGHT 320
+#define UI_HOR_RES    320
+#define UI_VER_RES    240
+#endif
 
 #define CYD_TOUCH_IRQ  36
 #define CYD_TOUCH_MOSI 32
@@ -10,10 +22,11 @@
 #define CYD_TOUCH_CLK  25
 #define CYD_TOUCH_CS   33
 
-// 三脚按键模块 OUT/S → GPIO22（VCC→3.3V，GND→GND）
-#define BTN_PIN 22
+/* Map 320x240 design coordinates onto the active UI resolution (identity on 2.8"). */
+#define UX(x) ((int)(((long)(x) * (UI_HOR_RES)) / 320))
+#define UY(y) ((int)(((long)(y) * (UI_VER_RES)) / 240))
+#define UW(w) UX(w)
+#define UH(h) UY(h)
 
-#define SCREEN_WIDTH  240
-#define SCREEN_HEIGHT 320
-#define UI_HOR_RES    320
-#define UI_VER_RES    240
+
+#define BTN_PIN 22
diff --git a/platformio.ini b/platformio.ini
index d818c5c..18941b3 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -54,3 +54,20 @@ build_flags =
   -I${PROJECT_DIR}/include
 
 extra_scripts = pre:copy_lv_conf.py
+
+; Optional 3.5" CYD ESP32-3248S035 (ST7796 resistive). Default remains [env:cyd].
+; Build: pio run -e cyd_35r
+[env:cyd_35r]
+extends = env:cyd
+build_flags =
+  ${env:cyd.build_flags}
+  -UILI9341_2_DRIVER
+  -DST7796_DRIVER=1
+  -UTFT_WIDTH
+  -UTFT_HEIGHT
+  -DTFT_WIDTH=320
+  -DTFT_HEIGHT=480
+  -UTFT_BL
+  -DTFT_BL=27
+  -DCYD_BOARD_3248S035=1
+
diff --git a/src/ui.cpp b/src/ui.cpp
index 49dcc5d..c4b2b60 100644
--- a/src/ui.cpp
+++ b/src/ui.cpp
@@ -66,41 +66,41 @@ void ui_create() {
   lv_label_set_text(lbl_title, "Button");
   lv_obj_set_style_text_color(lbl_title, lv_color_hex(COL_INK), 0);
   lv_obj_set_style_text_font(lbl_title, &lv_font_montserrat_28, 0);
-  lv_obj_align(lbl_title, LV_ALIGN_TOP_MID, 0, 4);
+  lv_obj_align(lbl_title, LV_ALIGN_TOP_MID, UX(0), UY(4));
 
   lbl_pin = lv_label_create(scr);
   lv_label_set_text_fmt(lbl_pin, "OUT->GPIO%d  VCC 3.3V", BTN_PIN);
   lv_obj_set_style_text_color(lbl_pin, lv_color_hex(COL_MUTED), 0);
   lv_obj_set_style_text_font(lbl_pin, &lv_font_montserrat_14, 0);
-  lv_obj_align(lbl_pin, LV_ALIGN_TOP_MID, 0, 36);
+  lv_obj_align(lbl_pin, LV_ALIGN_TOP_MID, UX(0), UY(36));
 
   lbl_count = lv_label_create(scr);
   lv_label_set_text(lbl_count, "0");
   lv_obj_set_style_text_color(lbl_count, lv_color_hex(COL_ACCENT), 0);
   lv_obj_set_style_text_font(lbl_count, &lv_font_montserrat_28, 0);
-  lv_obj_align(lbl_count, LV_ALIGN_TOP_MID, 0, 68);
+  lv_obj_align(lbl_count, LV_ALIGN_TOP_MID, UX(0), UY(68));
 
   lbl_hint = lv_label_create(scr);
   lv_label_set_text(lbl_hint, "count");
   lv_obj_set_style_text_color(lbl_hint, lv_color_hex(COL_MUTED), 0);
   lv_obj_set_style_text_font(lbl_hint, &lv_font_montserrat_14, 0);
-  lv_obj_align(lbl_hint, LV_ALIGN_TOP_MID, 0, 104);
+  lv_obj_align(lbl_hint, LV_ALIGN_TOP_MID, UX(0), UY(104));
 
   lbl_state = lv_label_create(scr);
   lv_label_set_text(lbl_state, "IDLE");
   lv_obj_set_style_text_color(lbl_state, lv_color_hex(COL_MUTED), 0);
   lv_obj_set_style_text_font(lbl_state, &lv_font_montserrat_20, 0);
-  lv_obj_align(lbl_state, LV_ALIGN_TOP_MID, 0, 126);
+  lv_obj_align(lbl_state, LV_ALIGN_TOP_MID, UX(0), UY(126));
 
   lbl_raw = lv_label_create(scr);
   lv_label_set_text(lbl_raw, "OUT --");
   lv_obj_set_style_text_color(lbl_raw, lv_color_hex(COL_MUTED), 0);
   lv_obj_set_style_text_font(lbl_raw, &lv_font_montserrat_14, 0);
-  lv_obj_align(lbl_raw, LV_ALIGN_TOP_MID, 0, 152);
+  lv_obj_align(lbl_raw, LV_ALIGN_TOP_MID, UX(0), UY(152));
 
   btn_reset = lv_button_create(scr);
-  lv_obj_set_size(btn_reset, UI_HOR_RES - 48, 44);
-  lv_obj_align(btn_reset, LV_ALIGN_TOP_MID, 0, 184);
+  lv_obj_set_size(btn_reset, UI_HOR_RES - UW(48), UH(44));
+  lv_obj_align(btn_reset, LV_ALIGN_TOP_MID, UX(0), UY(184));
   style_btn(btn_reset, COL_BTN);
   lv_obj_add_event_cb(btn_reset, on_reset, LV_EVENT_CLICKED, nullptr);
   lbl_reset = lv_label_create(btn_reset);