added an rc switch for arming and disarming with the option to use it as a button

src/modules/sensors/parameters.cpp

@@ -90,6 +90,7 @@ int initialize_parameter_handles(ParameterHandles &parameter_handles)
 	parameter_handles.rc_map_acro_sw = param_find("RC_MAP_ACRO_SW");
 	parameter_handles.rc_map_offboard_sw = param_find("RC_MAP_OFFB_SW");
 	parameter_handles.rc_map_kill_sw = param_find("RC_MAP_KILL_SW");
+	parameter_handles.rc_map_arm_sw = param_find("RC_MAP_ARM_SW");
 	parameter_handles.rc_map_trans_sw = param_find("RC_MAP_TRANS_SW");
 	parameter_handles.rc_map_gear_sw = param_find("RC_MAP_GEAR_SW");
 
@@ -120,6 +121,7 @@ int initialize_parameter_handles(ParameterHandles &parameter_handles)
 	parameter_handles.rc_acro_th = param_find("RC_ACRO_TH");
 	parameter_handles.rc_offboard_th = param_find("RC_OFFB_TH");
 	parameter_handles.rc_killswitch_th = param_find("RC_KILLSWITCH_TH");
+	parameter_handles.rc_armswitch_th = param_find("RC_ARMSWITCH_TH");
 	parameter_handles.rc_trans_th = param_find("RC_TRANS_TH");
 	parameter_handles.rc_gear_th = param_find("RC_GEAR_TH");
 
@@ -313,6 +315,10 @@ int update_parameters(const ParameterHandles &parameter_handles, Parameters &par
 		PX4_WARN("%s", paramerr);
 	}
 
+	if (param_get(parameter_handles.rc_map_arm_sw, &(parameters.rc_map_arm_sw)) != OK) {
+		PX4_WARN("%s", paramerr);
+	}
+
 	if (param_get(parameter_handles.rc_map_trans_sw, &(parameters.rc_map_trans_sw)) != OK) {
 		PX4_WARN("%s", paramerr);
 	}
@@ -365,6 +371,9 @@ int update_parameters(const ParameterHandles &parameter_handles, Parameters &par
 	param_get(parameter_handles.rc_killswitch_th, &(parameters.rc_killswitch_th));
 	parameters.rc_killswitch_inv = (parameters.rc_killswitch_th < 0);
 	parameters.rc_killswitch_th = fabs(parameters.rc_killswitch_th);
+	param_get(parameter_handles.rc_armswitch_th, &(parameters.rc_armswitch_th));
+	parameters.rc_armswitch_inv = (parameters.rc_armswitch_th < 0);
+	parameters.rc_armswitch_th = fabs(parameters.rc_armswitch_th);
 	param_get(parameter_handles.rc_trans_th, &(parameters.rc_trans_th));
 	parameters.rc_trans_inv = (parameters.rc_trans_th < 0);
 	parameters.rc_trans_th = fabs(parameters.rc_trans_th);

src/modules/sensors/parameters.h

@@ -83,6 +83,7 @@ struct Parameters {
 	int rc_map_acro_sw;
 	int rc_map_offboard_sw;
 	int rc_map_kill_sw;
+	int rc_map_arm_sw;
 	int rc_map_trans_sw;
 	int rc_map_gear_sw;
 
@@ -108,6 +109,7 @@ struct Parameters {
 	float rc_acro_th;
 	float rc_offboard_th;
 	float rc_killswitch_th;
+	float rc_armswitch_th;
 	float rc_trans_th;
 	float rc_gear_th;
 	bool rc_assist_inv;
@@ -119,6 +121,7 @@ struct Parameters {
 	bool rc_acro_inv;
 	bool rc_offboard_inv;
 	bool rc_killswitch_inv;
+	bool rc_armswitch_inv;
 	bool rc_trans_inv;
 	bool rc_gear_inv;
 
@@ -159,6 +162,7 @@ struct ParameterHandles {
 	param_t rc_map_acro_sw;
 	param_t rc_map_offboard_sw;
 	param_t rc_map_kill_sw;
+	param_t rc_map_arm_sw;
 	param_t rc_map_trans_sw;
 	param_t rc_map_gear_sw;
 
@@ -188,6 +192,7 @@ struct ParameterHandles {
 	param_t rc_acro_th;
 	param_t rc_offboard_th;
 	param_t rc_killswitch_th;
+	param_t rc_armswitch_th;
 	param_t rc_trans_th;
 	param_t rc_gear_th;
 

src/modules/sensors/rc_update.cpp

@@ -414,6 +414,8 @@ RCUpdate::rc_poll(const ParameterHandles &parameter_handles)
 						 _parameters.rc_offboard_th, _parameters.rc_offboard_inv);
 			manual.kill_switch = get_rc_sw2pos_position(rc_channels_s::RC_CHANNELS_FUNCTION_KILLSWITCH,
 					     _parameters.rc_killswitch_th, _parameters.rc_killswitch_inv);
+			manual.arm_switch = get_rc_sw2pos_position(rc_channels_s::RC_CHANNELS_FUNCTION_KILLSWITCH,
+					    _parameters.rc_armswitch_th, _parameters.rc_armswitch_inv);
 			manual.transition_switch = get_rc_sw2pos_position(rc_channels_s::RC_CHANNELS_FUNCTION_TRANSITION,
 						   _parameters.rc_trans_th, _parameters.rc_trans_inv);
 			manual.gear_switch = get_rc_sw2pos_position(rc_channels_s::RC_CHANNELS_FUNCTION_GEAR,

src/modules/sensors/sensor_params.c

@@ -2488,6 +2488,34 @@ PARAM_DEFINE_INT32(RC_MAP_OFFB_SW, 0);
  */
 PARAM_DEFINE_INT32(RC_MAP_KILL_SW, 0);
 
+/**
+ * Arm switch channel
+ *
+ * @min 0
+ * @max 18
+ * @group Radio Switches
+ * @value 0 Unassigned
+ * @value 1 Channel 1
+ * @value 2 Channel 2
+ * @value 3 Channel 3
+ * @value 4 Channel 4
+ * @value 5 Channel 5
+ * @value 6 Channel 6
+ * @value 7 Channel 7
+ * @value 8 Channel 8
+ * @value 9 Channel 9
+ * @value 10 Channel 10
+ * @value 11 Channel 11
+ * @value 12 Channel 12
+ * @value 13 Channel 13
+ * @value 14 Channel 14
+ * @value 15 Channel 15
+ * @value 16 Channel 16
+ * @value 17 Channel 17
+ * @value 18 Channel 18
+ */
+PARAM_DEFINE_INT32(RC_MAP_ARM_SW, 0);
+
 /**
  * Flaps channel
  *
@@ -2985,6 +3013,24 @@ PARAM_DEFINE_FLOAT(RC_OFFB_TH, 0.5f);
  */
 PARAM_DEFINE_FLOAT(RC_KILLSWITCH_TH, 0.25f);
 
+/**
+ * Threshold for the arm switch
+ *
+ * 0-1 indicate where in the full channel range the threshold sits
+ * 		0 : min
+ * 		1 : max
+ * sign indicates polarity of comparison
+ * 		positive : true when channel>th
+ * 		negative : true when channel<th
+ *
+ * @min -1
+ * @max 1
+ * @group Radio Switches
+ *
+ *
+ */
+PARAM_DEFINE_FLOAT(RC_ARMSWITCH_TH, 0.25f);
+
 /**
  * Threshold for the VTOL transition switch
  *