Implement RC and DL failsafe action handling for multirotors

Move RC and DL failsafe actions handling from navigator to commander (credits to @AndreasAntener)
Separate manual kill switch handling via manual_lockdown to prevent override and release of software lockdown by RC switch

Other changes:
Add failsafe tune
Fix LED blinking for Pixracer
Return back support for rc inputs in simulator but now it is configurable via cmake

src/drivers/ardrone_interface/ardrone_interface.c

@@ -333,7 +333,7 @@ int ardrone_interface_thread_main(int argc, char *argv[])
 			/* for now only spin if armed and immediately shut down
 			 * if in failsafe
 			 */
-			if (armed.armed && !armed.lockdown) {
+			if (armed.armed && !(armed.lockdown || armed.manual_lockdown)) {
 				ardrone_mixing_and_output(ardrone_write, &actuator_controls);
 
 			} else {

src/drivers/navio_sysfs_pwm_out/navio_sysfs_pwm_out.cpp

@@ -373,7 +373,7 @@ void task_main(int argc, char *argv[])
 				       pwm,
 				       &_pwm_limit);
 
-			if (_armed.lockdown) {
+			if (_armed.lockdown || _armed.manual_lockdown) {
 				send_outputs_pwm(disarmed_pwm);
 
 			} else {

src/drivers/pwm_out_sim/pwm_out_sim.cpp

@@ -88,6 +88,8 @@ class PWMSim : public device::CDev
 class PWMSim : public device::VDev
 #endif
 {
+	const uint32_t PWM_SIM_DISARMED_MAGIC = 900;
+	const uint32_t PWM_SIM_FAILSAFE_MAGIC = 600;
 public:
 	enum Mode {
 		MODE_2PWM,
@@ -128,6 +130,8 @@ private:
 
 	volatile bool	_task_should_exit;
 	static bool	_armed;
+	static bool	_lockdown;
+	static bool	_failsafe;
 
 	MixerGroup	*_mixers;
 
@@ -170,6 +174,8 @@ PWMSim	*g_pwm_sim;
 } // namespace
 
 bool PWMSim::_armed = false;
+bool PWMSim::_lockdown = false;
+bool PWMSim::_failsafe = false;
 
 PWMSim::PWMSim() :
 #ifdef __PX4_NUTTX
@@ -508,10 +514,23 @@ PWMSim::task_main()
 					 * This will be clearly visible on the servo status and will limit the risk of accidentally
 					 * spinning motors. It would be deadly in flight.
 					 */
-					outputs.output[i] = 900;
+					outputs.output[i] = PWM_SIM_DISARMED_MAGIC;
 				}
 			}
 
+			/* overwrite outputs in case of force_failsafe */
+			if (_failsafe) {
+				for (size_t i = 0; i < num_outputs; i++) {
+					outputs.output[i] = PWM_SIM_FAILSAFE_MAGIC;
+				}
+			}
+
+			/* overwrite outputs in case of lockdown */
+			if (_lockdown) {
+				for (size_t i = 0; i < num_outputs; i++) {
+					outputs.output[i] = 0.0;
+				}
+			}
 
 			/* and publish for anyone that cares to see */
 			orb_publish(ORB_ID(actuator_outputs), _outputs_pub, &outputs);
@@ -526,6 +545,8 @@ PWMSim::task_main()
 			orb_copy(ORB_ID(actuator_armed), _armed_sub, &aa);
 			/* do not obey the lockdown value, as lockdown is for PWMSim */
 			_armed = aa.armed;
+			_failsafe = aa.force_failsafe;
+			_lockdown = aa.lockdown || aa.manual_lockdown;
 		}
 	}
 

src/drivers/px4fmu/fmu.cpp

@@ -1200,8 +1200,15 @@ PX4FMU::cycle()
 				       _disarmed_pwm, _min_pwm, _max_pwm, outputs, pwm_limited, &_pwm_limit);
 
 
+			/* overwrite outputs in case of force_failsafe with _failsafe_pwm PWM values */
+			if (_armed.force_failsafe) {
+				for (size_t i = 0; i < num_outputs; i++) {
+					pwm_limited[i] = _failsafe_pwm[i];
+				}
+			}
+
 			/* overwrite outputs in case of lockdown with disarmed PWM values */
-			if (_armed.lockdown) {
+			if (_armed.lockdown || _armed.manual_lockdown) {
 				for (size_t i = 0; i < num_outputs; i++) {
 					pwm_limited[i] = _disarmed_pwm[i];
 				}

src/drivers/px4io/px4io.cpp

@@ -1462,11 +1462,11 @@ PX4IO::io_set_arming_state()
 
 		_armed = armed.armed;
 
-		if (armed.lockdown && !_lockdown_override) {
+		if ((armed.lockdown || armed.manual_lockdown) && !_lockdown_override) {
 			set |= PX4IO_P_SETUP_ARMING_LOCKDOWN;
 			_lockdown_override = true;
 
-		} else if (!armed.lockdown && _lockdown_override) {
+		} else if (!(armed.lockdown || armed.manual_lockdown) && _lockdown_override) {
 			clear |= PX4IO_P_SETUP_ARMING_LOCKDOWN;
 			_lockdown_override = false;
 		}