Configurable OSD refresh rate

docs/Settings.md

@@ -4842,6 +4842,16 @@ Force OSD to work in grid mode even if the OSD device supports pixel level acces
 
 ---
 
+### osd_framerate_hz
+
+Target refresh rate for OSD elements in Hz. Each element is redrawn at approximately this rate. Values above 10 Hz provide no visible improvement for typical flight data but increase CPU load. Artificial horizon and telemetry are always updated every cycle regardless of this setting. Set to -1 for legacy behavior (one element per frame).
+
+| Default | Min | Max |
+| --- | --- | --- |
+| -1 | -1 | 15 |
+
+---
+
 ### osd_gforce_alarm
 
 Value above which the OSD g force indicator will blink (g)

src/main/build/debug.h

@@ -79,6 +79,7 @@ typedef enum {
     DEBUG_GPS,
     DEBUG_LULU,
     DEBUG_SBUS2,
+    DEBUG_OSD_REFRESH,
     DEBUG_COUNT // also update debugModeNames in cli.c
 } debugType_e;
 

src/main/fc/cli.c

@@ -219,7 +219,8 @@ static const char *debugModeNames[DEBUG_COUNT] = {
     "HEADTRACKER",
     "GPS",
     "LULU",
-    "SBUS2"
+    "SBUS2",
+    "OSD_REFRESH"
 };
 
 /* Sensor names (used in lookup tables for *_hardware settings and in status

src/main/fc/settings.yaml

@@ -84,7 +84,7 @@ tables:
       "VIBE", "CRUISE", "REM_FLIGHT_TIME", "SMARTAUDIO", "ACC",
       "NAV_YAW", "PCF8574", "DYN_GYRO_LPF", "AUTOLEVEL", "ALTITUDE",
       "AUTOTRIM", "AUTOTUNE", "RATE_DYNAMICS", "LANDING", "POS_EST",
-      "ADAPTIVE_FILTER", "HEADTRACKER", "GPS", "LULU", "SBUS2"]
+      "ADAPTIVE_FILTER", "HEADTRACKER", "GPS", "LULU", "SBUS2", "OSD_REFRESH"]
   - name: aux_operator
     values: ["OR", "AND"]
     enum: modeActivationOperator_e
@@ -3329,6 +3329,13 @@ groups:
         max: 600
         type: int16_t
         field: msp_displayport_fullframe_interval
+      - name: osd_framerate_hz
+        description: "Target refresh rate for OSD elements in Hz. Each element is redrawn at approximately this rate. Values above 10 Hz provide no visible improvement for typical flight data but increase CPU load. Artificial horizon and telemetry are always updated every cycle regardless of this setting. Set to -1 for legacy behavior (one element per frame)."
+        default_value: -1
+        min: -1
+        max: 15
+        type: int8_t
+        field: osd_framerate_hz
       - name: osd_units
         description: "IMPERIAL, METRIC, UK"
         default_value: "METRIC"

src/main/io/osd.c

@@ -29,6 +29,7 @@
 #include <ctype.h>
 #include <math.h>
 #include <inttypes.h>
+#include <limits.h>
 
 #include "platform.h"
 
@@ -4245,15 +4246,48 @@ uint8_t osdIncElementIndex(uint8_t elementIndex)
 void osdDrawNextElement(void)
 {
     static uint8_t elementIndex = 0;
-    // Flag for end of loop, also prevents infinite loop when no elements are enabled
-    uint8_t index = elementIndex;
-    do {
-        elementIndex = osdIncElementIndex(elementIndex);
-    } while (!osdDrawSingleElement(elementIndex) && index != elementIndex);
+    static uint8_t activeElements = 0;
+    static unsigned lastLayout = UINT_MAX;
+
+    // Recount visible elements on layout change
+    if (currentLayout != lastLayout) {
+        lastLayout = currentLayout;
+        activeElements = 0;
+        uint8_t idx = 0;
+        do {
+            idx = osdIncElementIndex(idx);
+            if (OSD_VISIBLE(osdLayoutsConfig()->item_pos[currentLayout][idx])) {
+                activeElements++;
+            }
+        } while (idx > 0);
+    }
+
+    int8_t framerate_hz = osdConfig()->osd_framerate_hz;
+
+    uint8_t elementsPerCycle;
+    if (framerate_hz <= 0 || activeElements == 0) {
+        elementsPerCycle = 1; // legacy: one element per cycle
+    } else {
+        elementsPerCycle = ((uint16_t)activeElements * framerate_hz * 2 + 124) / 125;
+        if (elementsPerCycle < 1) elementsPerCycle = 1;
+        if (elementsPerCycle > activeElements) elementsPerCycle = activeElements;
+    }
+
+    DEBUG_SET(DEBUG_OSD_REFRESH, 0, elementsPerCycle);
+    DEBUG_SET(DEBUG_OSD_REFRESH, 1, activeElements);
+    DEBUG_SET(DEBUG_OSD_REFRESH, 2, elementIndex);
+    DEBUG_SET(DEBUG_OSD_REFRESH, 3, framerate_hz);
+
+    for (uint8_t i = 0; i < elementsPerCycle; i++) {
+        uint8_t index = elementIndex;
+        do {
+            elementIndex = osdIncElementIndex(elementIndex);
+        } while (!osdDrawSingleElement(elementIndex) && index != elementIndex);
+    }
 
     // Draw artificial horizon + tracking telemetry last
     osdDrawSingleElement(OSD_ARTIFICIAL_HORIZON);
-    if (osdConfig()->telemetry>0){
+    if (osdConfig()->telemetry > 0) {
         osdDisplayTelemetry();
     }
 }
@@ -4304,6 +4338,7 @@ 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,
+    .osd_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,

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;