PWM automatic trigger system (ATS) for parachutes (#13726)

* parameter and logic to commander for triggering failsafe from external automatic trigger system.
* logic to startup script for enabling ATS. Added uORB publishing to pwm_input module.
* Refactored out CDev usage from pwm_input and ll40ls. Refactored out ll40ls specifics from pwm_input and cleaned up dead code.

src/modules/commander/failure_detector/FailureDetector.cpp

@@ -40,6 +40,8 @@
 
 #include "FailureDetector.hpp"
 
+using namespace time_literals;
+
 FailureDetector::FailureDetector(ModuleParams *parent) :
 	ModuleParams(parent)
 {
@@ -61,6 +63,10 @@ FailureDetector::update(const vehicle_status_s &vehicle_status)
 	if (isAttitudeStabilized(vehicle_status)) {
 		updated = updateAttitudeStatus();
 
+		if (_param_fd_ext_ats_en.get()) {
+			updated |= updateExternalAtsStatus();
+		}
+
 	} else {
 		updated = resetStatus();
 	}
@@ -111,8 +117,8 @@ FailureDetector::updateAttitudeStatus()
 		hrt_abstime time_now = hrt_absolute_time();
 
 		// Update hysteresis
-		_roll_failure_hysteresis.set_hysteresis_time_from(false, (hrt_abstime)(1e6f * _param_fd_fail_r_ttri.get()));
-		_pitch_failure_hysteresis.set_hysteresis_time_from(false, (hrt_abstime)(1e6f * _param_fd_fail_p_ttri.get()));
+		_roll_failure_hysteresis.set_hysteresis_time_from(false, (hrt_abstime)(1_s * _param_fd_fail_r_ttri.get()));
+		_pitch_failure_hysteresis.set_hysteresis_time_from(false, (hrt_abstime)(1_s * _param_fd_fail_p_ttri.get()));
 		_roll_failure_hysteresis.set_state_and_update(roll_status, time_now);
 		_pitch_failure_hysteresis.set_state_and_update(pitch_status, time_now);
 
@@ -132,3 +138,30 @@ FailureDetector::updateAttitudeStatus()
 
 	return updated;
 }
+
+bool
+FailureDetector::updateExternalAtsStatus()
+{
+	pwm_input_s pwm_input;
+	bool updated = _sub_pwm_input.update(&pwm_input);
+
+	if (updated) {
+
+		uint32_t pulse_width = pwm_input.pulse_width;
+		bool ats_trigger_status = (pulse_width >= (uint32_t)_param_fd_ext_ats_trig.get()) && (pulse_width < 3_ms);
+
+		hrt_abstime time_now = hrt_absolute_time();
+
+		// Update hysteresis
+		_ext_ats_failure_hysteresis.set_hysteresis_time_from(false, 100_ms); // 5 consecutive pulses at 50hz
+		_ext_ats_failure_hysteresis.set_state_and_update(ats_trigger_status, time_now);
+
+		_status &= ~FAILURE_EXT;
+
+		if (_ext_ats_failure_hysteresis.get_state()) {
+			_status |= FAILURE_EXT;
+		}
+	}
+
+	return updated;
+}

src/modules/commander/failure_detector/FailureDetector.hpp

@@ -48,17 +48,20 @@
 #include <px4_platform_common/module_params.h>
 #include <hysteresis/hysteresis.h>
 
+
 // subscriptions
 #include <uORB/Subscription.hpp>
 #include <uORB/topics/vehicle_attitude_setpoint.h>
 #include <uORB/topics/vehicle_attitude.h>
 #include <uORB/topics/vehicle_status.h>
+#include <uORB/topics/pwm_input.h>
 
 typedef enum {
 	FAILURE_NONE = vehicle_status_s::FAILURE_NONE,
 	FAILURE_ROLL = vehicle_status_s::FAILURE_ROLL,
 	FAILURE_PITCH = vehicle_status_s::FAILURE_PITCH,
 	FAILURE_ALT = vehicle_status_s::FAILURE_ALT,
+	FAILURE_EXT = vehicle_status_s::FAILURE_EXT,
 } failure_detector_bitmak;
 
 using uORB::SubscriptionData;
@@ -79,18 +82,24 @@ private:
 		(ParamInt<px4::params::FD_FAIL_P>) _param_fd_fail_p,
 		(ParamInt<px4::params::FD_FAIL_R>) _param_fd_fail_r,
 		(ParamFloat<px4::params::FD_FAIL_R_TTRI>) _param_fd_fail_r_ttri,
-		(ParamFloat<px4::params::FD_FAIL_P_TTRI>) _param_fd_fail_p_ttri
+		(ParamFloat<px4::params::FD_FAIL_P_TTRI>) _param_fd_fail_p_ttri,
+		(ParamBool<px4::params::FD_EXT_ATS_EN>) _param_fd_ext_ats_en,
+		(ParamInt<px4::params::FD_EXT_ATS_TRIG>) _param_fd_ext_ats_trig
 	)
 
 	// Subscriptions
 	uORB::Subscription _sub_vehicule_attitude{ORB_ID(vehicle_attitude)};
+	uORB::Subscription _sub_pwm_input{ORB_ID(pwm_input)};
+
 
 	uint8_t _status{FAILURE_NONE};
 
 	systemlib::Hysteresis _roll_failure_hysteresis{false};
 	systemlib::Hysteresis _pitch_failure_hysteresis{false};
+	systemlib::Hysteresis _ext_ats_failure_hysteresis{false};
 
 	bool resetStatus();
 	bool isAttitudeStabilized(const vehicle_status_s &vehicle_status);
 	bool updateAttitudeStatus();
+	bool updateExternalAtsStatus();
 };

src/modules/commander/failure_detector/failure_detector_params.c

@@ -103,3 +103,27 @@ PARAM_DEFINE_FLOAT(FD_FAIL_R_TTRI, 0.3);
  * @group Failure Detector
  */
 PARAM_DEFINE_FLOAT(FD_FAIL_P_TTRI, 0.3);
+
+/**
+ * Enable PWM input on AUX5 or MAIN5 (depending on board) for engaging failsafe from an external
+ * automatic trigger system (ATS).
+ *
+ * External ATS is required by ASTM F3322-18.
+ *
+ * @boolean
+ * @reboot_required true
+ * @group Failure Detector
+ */
+PARAM_DEFINE_INT32(FD_EXT_ATS_EN, 0);
+
+/**
+ * The PWM threshold from external automatic trigger system for engaging failsafe.
+ *
+ * External ATS is required by ASTM F3322-18.
+ *
+ * @unit microseconds
+ * @decimal 2
+ *
+ * @group Failure Detector
+ */
+PARAM_DEFINE_INT32(FD_EXT_ATS_TRIG, 1900);