Add support for displaying the debug[] array in the OSD

Element intentionally not added to the configurator nor CMS. Must
be set via CLI or MSP.

src/main/cms/cms_menu_osd.c

@@ -207,8 +207,10 @@ static const OSD_Entry menuOsdElemsEntries[] =
 };
 
 #if defined(VTX_COMMON) && defined(USE_GPS) && defined(USE_BARO) && defined(USE_PITOT)
-// All CMS OSD elements should be enabled in this case
-_Static_assert(ARRAYLEN(menuOsdElemsEntries) - 3 == OSD_ITEM_COUNT, "missing OSD elements in CMS");
+// All CMS OSD elements should be enabled in this case. The menu has 3 extra
+// elements (label, back and end), but there's an OSD element that we intentionally
+// don't show here (OSD_DEBUG).
+_Static_assert(ARRAYLEN(menuOsdElemsEntries) - 3 + 1 == OSD_ITEM_COUNT, "missing OSD elements in CMS");
 #endif
 
 const CMS_Menu menuOsdElements = {

src/main/io/osd.c

@@ -1737,6 +1737,16 @@ static bool osdDrawSingleElement(uint8_t item)
             break;
         }
 
+    case OSD_DEBUG:
+        {
+            // Longest representable string is -32768, hence 6 characters
+            tfp_sprintf(buff, "[0]=%6d [1]=%6d", debug[0], debug[1]);
+            displayWrite(osdDisplayPort, elemPosX, elemPosY, buff);
+            elemPosY++;
+            tfp_sprintf(buff, "[2]=%6d [3]=%6d", debug[2], debug[3]);
+            break;
+        }
+
     default:
         return false;
     }

src/main/io/osd.h

@@ -80,6 +80,7 @@ typedef enum {
     OSD_MAP_NORTH,
     OSD_MAP_TAKEOFF,
     OSD_RADAR,
+    OSD_DEBUG, // Number 46. Intentionally absent from configurator and CMS. Set it from CLI.
     OSD_ITEM_COUNT // MUST BE LAST
 } osd_items_e;