mixer: use an enum for airmode

src/drivers/linux_pwm_out/linux_pwm_out.cpp

@@ -116,7 +116,7 @@ static void subscribe();
 
 static void task_main(int argc, char *argv[]);
 
-static void update_params(int32_t &airmode);
+static void update_params(Mixer::Airmode &airmode);
 
 /* mixer initialization */
 int initialize_mixer(const char *mixer_filename);
@@ -135,7 +135,7 @@ int mixer_control_callback(uintptr_t handle,
 }
 
 
-void update_params(int32_t &airmode)
+void update_params(Mixer::Airmode &airmode)
 {
 	// multicopter air-mode
 	param_t param_handle = param_find("MC_AIRMODE");
@@ -255,7 +255,7 @@ void task_main(int argc, char *argv[])
 	// subscribe and set up polling
 	subscribe();
 
-	int32_t airmode = false;
+	Mixer::Airmode airmode = Mixer::Airmode::disabled;
 	update_params(airmode);
 	int params_sub = orb_subscribe(ORB_ID(parameter_update));
 

src/drivers/pwm_out_sim/PWMSim.hpp

@@ -131,7 +131,7 @@ private:
 	actuator_controls_s _controls[actuator_controls_s::NUM_ACTUATOR_CONTROL_GROUPS] {};
 	orb_id_t	_control_topics[actuator_controls_s::NUM_ACTUATOR_CONTROL_GROUPS] {};
 
-	int32_t 	_airmode{0}; 	///< multicopter air-mode
+	Mixer::Airmode 	_airmode{Mixer::Airmode::disabled}; 	///< multicopter air-mode
 
 	perf_counter_t	_perf_control_latency;
 

src/drivers/px4fmu/fmu.cpp

@@ -237,7 +237,7 @@ private:
 
 	float _mot_t_max;	///< maximum rise time for motor (slew rate limiting)
 	float _thr_mdl_fac;	///< thrust to pwm modelling factor
-	int32_t _airmode;	///< multicopter air-mode
+	Mixer::Airmode _airmode;	///< multicopter air-mode
 	MotorOrdering _motor_ordering;
 
 	perf_counter_t	_perf_control_latency;
@@ -321,7 +321,7 @@ PX4FMU::PX4FMU(bool run_as_task) :
 	_to_mixer_status(nullptr),
 	_mot_t_max(0.0f),
 	_thr_mdl_fac(0.0f),
-	_airmode(0),
+	_airmode(Mixer::Airmode::disabled),
 	_motor_ordering(MotorOrdering::PX4),
 	_perf_control_latency(perf_alloc(PC_ELAPSED, "fmu control latency"))
 {

src/drivers/snapdragon_pwm_out/snapdragon_pwm_out.cpp

@@ -138,7 +138,7 @@ static void subscribe();
 
 static void task_main(int argc, char *argv[]);
 
-static void update_params(int32_t &airmode);
+static void update_params(Mixer::Airmode &airmode);
 
 int initialize_mixer(const char *mixer_filename);
 
@@ -162,7 +162,7 @@ int mixer_control_callback(uintptr_t handle,
 	return 0;
 }
 
-void update_params(int32_t &airmode)
+void update_params(Mixer::Airmode &airmode)
 {
 	// multicopter air-mode
 	param_t param_handle = param_find("MC_AIRMODE");
@@ -355,7 +355,7 @@ void task_main(int argc, char *argv[])
 	// subscribe and set up polling
 	subscribe();
 
-	int32_t airmode = 0;
+	Mixer::Airmode airmode = Mixer::Airmode::disabled;
 	update_params(airmode);
 	int params_sub = orb_subscribe(ORB_ID(parameter_update));
 

src/drivers/tap_esc/tap_esc.cpp

@@ -141,7 +141,7 @@ private:
 	EscPacket 	_packet = {};
 
 	DEFINE_PARAMETERS(
-		(ParamBool<px4::params::MC_AIRMODE>) _airmode   ///< multicopter air-mode
+		(ParamInt<px4::params::MC_AIRMODE>) _airmode   ///< multicopter air-mode
 	)
 
 	void subscribe();
@@ -420,7 +420,7 @@ void TAP_ESC::cycle()
 	}
 
 	if (_mixers) {
-		_mixers->set_airmode(_airmode.get());
+		_mixers->set_airmode((Mixer::Airmode)_airmode.get());
 	}
 
 	/* check if anything updated */

src/drivers/uavcan/uavcan_main.hpp

@@ -210,7 +210,7 @@ private:
 
 	perf_counter_t			_perf_control_latency;
 
-	int32_t 			_airmode = 0;
+	Mixer::Airmode 			_airmode = Mixer::Airmode::disabled;
 
 	// index into _poll_fds for each _control_subs handle
 	uint8_t				_poll_ids[NUM_ACTUATOR_CONTROL_GROUPS_UAVCAN];

src/lib/mixer/mixer.h

@@ -140,6 +140,12 @@
 class __EXPORT Mixer
 {
 public:
+	enum class Airmode : int32_t {
+		disabled = 0,
+		roll_pitch = 1,
+		roll_pitch_yaw = 2
+	};
+
 	/** next mixer in a list */
 	Mixer				*_next;
 
@@ -223,7 +229,7 @@ public:
 	 *
 	 * @param[in]  airmode   Select airmode type (0 = disabled, 1 = roll/pitch, 2 = roll/pitch/yaw)
 	 */
-	virtual void set_airmode(int32_t airmode) {};
+	virtual void set_airmode(Airmode airmode) {};
 
 protected:
 	/** client-supplied callback used when fetching control values */
@@ -419,7 +425,7 @@ public:
 	 */
 	void	set_thrust_factor(float val) override;
 
-	void 	set_airmode(int32_t airmode) override;
+	void 	set_airmode(Airmode airmode) override;
 
 private:
 	Mixer				*_first;	/**< linked list of mixers */
@@ -667,7 +673,7 @@ public:
 	 */
 	void			set_thrust_factor(float val) override { _thrust_factor = val; }
 
-	void 			set_airmode(int32_t airmode) override;
+	void 			set_airmode(Airmode airmode) override;
 
 	union saturation_status {
 		struct {
@@ -694,7 +700,7 @@ private:
 	float 				_delta_out_max;
 	float 				_thrust_factor;
 
-	uint32_t			_airmode;
+	Airmode				_airmode;
 
 	void update_saturation_status(unsigned index, bool clipping_high, bool clipping_low);
 	saturation_status _saturation_status;

src/lib/mixer/mixer_group.cpp

@@ -188,7 +188,7 @@ MixerGroup::set_thrust_factor(float val)
 }
 
 void
-MixerGroup::set_airmode(int32_t airmode)
+MixerGroup::set_airmode(Airmode airmode)
 {
 	Mixer	*mixer = _first;
 

src/lib/mixer/mixer_multirotor.cpp

@@ -72,7 +72,7 @@ MultirotorMixer::MultirotorMixer(ControlCallback control_cb,
 	_idle_speed(-1.0f + idle_speed * 2.0f),	/* shift to output range here to avoid runtime calculation */
 	_delta_out_max(0.0f),
 	_thrust_factor(0.0f),
-	_airmode(0),
+	_airmode(Airmode::disabled),
 	_rotor_count(_config_rotor_count[(MultirotorGeometryUnderlyingType)geometry]),
 	_rotors(_config_index[(MultirotorGeometryUnderlyingType)geometry]),
 	_outputs_prev(new float[_rotor_count])
@@ -214,7 +214,7 @@ MultirotorMixer::mix(float *outputs, unsigned space)
 		boost = 1.0f - ((max_out - thrust) * roll_pitch_scale + thrust);
 	}
 
-	if (_airmode == 0) {
+	if (_airmode == Airmode::disabled) {
 		// disable positive boosting if not in air-mode
 		// boosting can only be positive when min_out < 0.0
 		// roll_pitch_scale is reduced accordingly
@@ -425,7 +425,7 @@ MultirotorMixer::update_saturation_status(unsigned index, bool clipping_high, bo
 }
 
 void
-MultirotorMixer::set_airmode(int32_t airmode)
+MultirotorMixer::set_airmode(Airmode airmode)
 {
 	_airmode = airmode;
 }

src/modules/mc_att_control/mc_att_control_params.c

@@ -569,14 +569,15 @@ PARAM_DEFINE_FLOAT(MC_DTERM_CUTOFF, 30.f);
  *
  * The air-mode enables the mixer to increase the total thrust of the multirotor
  * in order to keep attitude and rate control even at low and high throttle.
+ *
  * This function should be disabled during tuning as it will help the controller
- * to diverge if the closed-loop is unstable.
+ * to diverge if the closed-loop is unstable (i.e. the vehicle is not tuned yet).
  *
- * 0 = Disabled, 1 = Roll/Pitch, 2 = Roll/Pitch/Yaw
+ * Enabling air-mode for yaw requires the use of an arming switch.
  *
- * @min 0
- * @max 2
- * @decimal 0
+ * @value 0 Disabled
+ * @value 1 Roll/Pitch
+ * @value 2 Roll/Pitch/Yaw
  * @group Multicopter Attitude Control
  */
 PARAM_DEFINE_INT32(MC_AIRMODE, 0);

src/modules/px4iofirmware/mixer.cpp

@@ -259,7 +259,7 @@ mixer_tick(void)
 	/*
 	 * Update air-mode parameter
 	 */
-	mixer_group.set_airmode(REG_TO_BOOL(r_setup_airmode));
+	mixer_group.set_airmode((Mixer::Airmode)REG_TO_SIGNED(r_setup_airmode));
 
 
 	/*