Enable arbitrary euler angle for Mag rotation CAL_MAGx_{ROLL,PITCH,YAW}

- Enable arbitrary euler angle for Mag rotation
  - new CUSTOM rotation enum out of the normal enum range
 - mag_rot: automatically change to custom if euler rot is set
 - sensor_calibration: Magnetometer save custom rotation parameters
 - mag_cal: cross mention rotation parameters
  - This allows the user to see the RPY options when searching for the rotation parameter

---------

Co-authored-by: Junwoo Hwang <junwoo@auterion.com>
Co-authored-by: bresch <[brescianimathieu@gmail.com](mailto:brescianimathieu@gmail.com)>
Co-authored-by: Daniel Agar <daniel@agar.ca>

src/modules/commander/mag_calibration.cpp

@@ -771,6 +771,10 @@ calibrate_return mag_calibrate_all(orb_advert_t *mavlink_log_pub, int32_t cal_ma
 
 							// FALLTHROUGH
 							case ROTATION_PITCH_180_YAW_270: // skip 27, same as 10 ROTATION_ROLL_180_YAW_90
+
+							// FALLTHROUGH
+							case ROTATION_CUSTOM: // Skip, as we currently don't support detecting arbitrary euler angle orientation
+
 								MSE[r] = FLT_MAX;
 								break;
 
@@ -831,6 +835,11 @@ calibrate_return mag_calibrate_all(orb_advert_t *mavlink_log_pub, int32_t cal_ma
 									 worker_data.calibration[cur_mag].device_id(), worker_data.calibration[cur_mag].rotation_enum());
 								continue;
 
+							case ROTATION_CUSTOM:
+								PX4_INFO("[cal] External Mag: %d (%" PRIu32 "), not setting rotation enum since it's specified by Euler Angle",
+									 cur_mag, worker_data.calibration[cur_mag].device_id());
+								continue; // Continue to the next mag loop
+
 							default:
 								break;
 							}

src/modules/mavlink/mavlink_messages.cpp

@@ -228,8 +228,13 @@ static_assert(MAV_SENSOR_ROTATION_ROLL_90_PITCH_68_YAW_293 == static_cast<MAV_SE
 static_assert(MAV_SENSOR_ROTATION_PITCH_315 == static_cast<MAV_SENSOR_ORIENTATION>(ROTATION_PITCH_315), "Pitch: 315");
 static_assert(MAV_SENSOR_ROTATION_ROLL_90_PITCH_315 == static_cast<MAV_SENSOR_ORIENTATION>(ROTATION_ROLL_90_PITCH_315),
 	      "Roll: 90, Pitch: 315");
+
+// Note: Update the number (41, as of writing) below to the number of 'normal' rotation enums in MAVLink spec:
+// https://mavlink.io/en/messages/common.html#MAV_SENSOR_ORIENTATION
 static_assert(41 == ROTATION_MAX, "Keep MAV_SENSOR_ROTATION and PX4 Rotation in sync");
 
+static_assert(MAV_SENSOR_ROTATION_CUSTOM == static_cast<MAV_SENSOR_ORIENTATION>(ROTATION_CUSTOM), "Custom Rotation");
+
 
 static const StreamListItem streams_list[] = {
 #if defined(HEARTBEAT_HPP)

src/modules/sensors/module.yaml

@@ -360,6 +360,7 @@ parameters:
                 short: Magnetometer ${i} rotation relative to airframe
                 long: |
                     An internal sensor will force a value of -1, so a GCS should only attempt to configure the rotation if the value is greater than or equal to zero.
+                    Set to "Custom Euler Angle" to define the rotation using CAL_MAG${i}_ROLL, CAL_MAG${i}_PITCH and CAL_MAG${i}_YAW.
             category: System
             type: enum
             values:
@@ -405,12 +406,52 @@ parameters:
                 38: Roll 90°, Pitch 68°, Yaw 293°
                 39: Pitch 315°
                 40: Roll 90°, Pitch 315°
+                100: Custom Euler Angle
             min: -1
-            max: 40
+            max: 100
             default: -1
             num_instances: *max_num_sensor_instances
             instance_start: 0
 
+        CAL_MAG${i}_ROLL:
+            description:
+                short: Magnetometer ${i} Custom Euler Roll Angle
+                long: Setting this parameter changes CAL_MAG${i}_ROT to "Custom Euler Angle"
+            category: System
+            type: float
+            default: 0.0
+            min: -180
+            max: 180
+            unit: deg
+            num_instances: *max_num_sensor_instances
+            instance_start: 0
+
+        CAL_MAG${i}_PITCH:
+            description:
+                short: Magnetometer ${i} Custom Euler Pitch Angle
+                long: Setting this parameter changes CAL_MAG${i}_ROT to "Custom Euler Angle"
+            category: System
+            type: float
+            default: 0.0
+            min: -180
+            max: 180
+            unit: deg
+            num_instances: *max_num_sensor_instances
+            instance_start: 0
+
+        CAL_MAG${i}_YAW:
+            description:
+                short: Magnetometer ${i} Custom Euler Yaw Angle
+                long: Setting this parameter changes CAL_MAG${i}_ROT to "Custom Euler Angle"
+            category: System
+            type: float
+            default: 0.0
+            min: -180
+            max: 180
+            unit: deg
+            num_instances: *max_num_sensor_instances
+            instance_start: 0
+
         CAL_MAG${i}_XOFF:
             description:
                 short: Magnetometer ${i} X-axis offset