Add configurable OSD element refresh rate

Author: hntirgeam

src/main/fc/settings.yaml

@@ -3329,6 +3329,13 @@ groups:
         max: 600
         type: int16_t
         field: msp_displayport_fullframe_interval
+      - name: osd_framerate_hz
+        description: "OSD element refresh rate in Hz. Controls how often OSD elements are updated (except artificial horizon and telemetry which are always updated). Higher values provide smoother updates but increase CPU load. Set to -1 for legacy mode (one element per frame). Default: -1"
+        default_value: -1
+        min: -1
+        max: 60
+        type: int8_t
+        field: osd_framerate_hz
       - name: osd_units
         description: "IMPERIAL, METRIC, UK"
         default_value: "METRIC"

src/main/io/osd.c

@@ -4242,6 +4242,18 @@ uint8_t osdIncElementIndex(uint8_t elementIndex)
     return elementIndex;
 }
 
+static void osdDrawAllElements(void)
+{
+    for (uint8_t element = 0; element < OSD_ITEM_COUNT; element++) {
+        osdDrawSingleElement(element);
+    }
+
+    osdDrawSingleElement(OSD_ARTIFICIAL_HORIZON);
+    if (osdConfig()->telemetry>0){
+        osdDisplayTelemetry();
+    }
+}
+
 void osdDrawNextElement(void)
 {
     static uint8_t elementIndex = 0;
@@ -4304,6 +4316,7 @@ PG_RESET_TEMPLATE(osdConfig_t, osdConfig,
     .video_system = SETTING_OSD_VIDEO_SYSTEM_DEFAULT,
     .row_shiftdown = SETTING_OSD_ROW_SHIFTDOWN_DEFAULT,
     .msp_displayport_fullframe_interval = SETTING_OSD_MSP_DISPLAYPORT_FULLFRAME_INTERVAL_DEFAULT,
+    .framerate_hz = SETTING_OSD_FRAMERATE_HZ_DEFAULT,
 
     .ahi_reverse_roll = SETTING_OSD_AHI_REVERSE_ROLL_DEFAULT,
     .ahi_max_pitch = SETTING_OSD_AHI_MAX_PITCH_DEFAULT,
@@ -5976,7 +5989,28 @@ static void osdRefresh(timeUs_t currentTimeUs)
             displayClearScreen(osdDisplayPort);
             fullRedraw = false;
         }
-        osdDrawNextElement();
+
+        if (osdConfig()->osd_framerate_hz == -1) {
+            osdDrawNextElement();
+        } else {
+            static uint32_t lastDrawAllTimeUs = 0;
+            const int8_t hz = osdConfig()->osd_framerate_hz;
+            const uint32_t drawAllIntervalUs = (hz > 0) ? (1000000 / hz) : 0;
+
+            const bool forceDraw = (drawAllIntervalUs == 0);
+            const bool intervalExceeded = (currentTimeUs - lastDrawAllTimeUs) >= drawAllIntervalUs;
+
+            if (forceDraw || intervalExceeded) {
+                osdDrawAllElements();
+                lastDrawAllTimeUs = currentTimeUs;
+            }
+
+            osdDrawSingleElement(OSD_ARTIFICIAL_HORIZON);
+            if (osdConfig()->telemetry>0){
+                osdDisplayTelemetry();
+            }
+        }
+
         displayHeartbeat(osdDisplayPort);
         displayCommitTransaction(osdDisplayPort);
 #ifdef OSD_CALLS_CMS

src/main/io/osd.h

@@ -451,6 +451,7 @@ typedef struct osdConfig_s {
     videoSystem_e   video_system;
     uint8_t         row_shiftdown;
     int16_t         msp_displayport_fullframe_interval;
+    int8_t          osd_framerate_hz;
 
     // Preferences
     uint8_t         main_voltage_decimals;