Add ACC_CALIB arming disabled reason if ACC is required but not calibrated

Checks various features, modes, and OSD elements to determine if ACC is needed. Generates an arming disabled warning if ACC calibration has never been completed.

src/main/fc/core.c

@@ -214,6 +214,61 @@ void resetArmingDisabled(void)
     lastArmingDisabledReason = 0;
 }
 
+#ifdef USE_ACC
+static bool accNeedsCalibration(void)
+{
+    if (sensors(SENSOR_ACC)) {
+
+        // Check to see if the ACC has already been calibrated
+        if (accelerometerConfig()->calibrationCompleted ||
+            accelerometerConfig()->accZero.values.roll != 0 ||
+            accelerometerConfig()->accZero.values.pitch != 0 ||
+            accelerometerConfig()->accZero.values.yaw != 0) {
+
+            return false;
+        }
+
+        // We've determined that there's a detected ACC that has not
+        // yet been calibrated. Check to see if anything is using the
+        // ACC that would be affected by the lack of calibration.
+
+        // Check for any configured modes that use the ACC
+        if (isModeActivationConditionPresent(BOXANGLE) ||
+            isModeActivationConditionPresent(BOXHORIZON) ||
+            isModeActivationConditionPresent(BOXGPSRESCUE) ||
+            isModeActivationConditionPresent(BOXCAMSTAB) ||
+            isModeActivationConditionPresent(BOXCALIB) ||
+            isModeActivationConditionPresent(BOXACROTRAINER)) {
+
+            return true;
+        }
+
+        // Launch Control only requires the ACC if a angle limit is set
+        if (isModeActivationConditionPresent(BOXLAUNCHCONTROL) && currentPidProfile->launchControlAngleLimit) {
+            return true;
+        }
+
+#ifdef USE_OSD
+        // Check for any enabled OSD elements that need the ACC
+        if (featureIsEnabled(FEATURE_OSD)) {
+            if (osdNeedsAccelerometer()) {
+                return true;
+            }
+        }
+#endif
+
+#ifdef USE_GPS_RESCUE
+        // Check if failsafe will use GPS Rescue
+        if (failsafeConfig()->failsafe_procedure == FAILSAFE_PROCEDURE_GPS_RESCUE) {
+            return true;
+        }
+#endif
+    }
+
+    return false;
+}
+#endif
+
 void updateArmingStatus(void)
 {
     if (ARMING_FLAG(ARMED)) {
@@ -328,6 +383,14 @@ void updateArmingStatus(void)
             setArmingDisabled(ARMING_DISABLED_PARALYZE);
         }
 
+#ifdef USE_ACC
+        if (accNeedsCalibration()) {
+            setArmingDisabled(ARMING_DISABLED_ACC_CALIBRATION);
+        } else {
+            unsetArmingDisabled(ARMING_DISABLED_ACC_CALIBRATION);
+        }
+#endif
+
         if (!isUsingSticksForArming()) {
           /* Ignore ARMING_DISABLED_CALIBRATING if we are going to calibrate gyro on first arm */
           bool ignoreGyro = armingConfig()->gyro_cal_on_first_arm