feat: use RTC backup for EM on BW F4 1Mb flash radio (#5686)

radio/src/main.cpp

@@ -547,7 +547,13 @@ void perMain()
 
 #if defined(RTC_BACKUP_RAM)
   if (UNEXPECTED_SHUTDOWN()) {
+#if defined(COLORLCD)
     drawFatalErrorScreen(STR_EMERGENCY_MODE);
+#else
+    lcdClear();
+    menuMainView(0);
+    lcdRefresh();
+#endif
     return;
   }
 #endif

radio/src/targets/taranis/CMakeLists.txt

@@ -520,11 +520,13 @@ elseif ((CPU_TYPE_FULL STREQUAL STM32F407xE) OR (CPU_TYPE_FULL STREQUAL STM32F40
   if (CPU_TYPE_FULL STREQUAL STM32F407xG)
     set(TARGET_FLASH_SIZE 1M)
     add_definitions(-DSTM32F407xG)
+    set(RTC_BACKUP_RAM YES)
   else()
     set(USBJ_EX OFF)
   endif()
 elseif (CPU_TYPE_FULL STREQUAL STM32F413xG)
   set(CPU_TYPE STM32F4)
+  set(RTC_BACKUP_RAM YES)
   add_definitions(-DSTM32F40_41xxx -DSTM32F413xx)
   set(TARGET_LINKER_DIR stm32f413)
 else()