AP_ADSB: Allow for multiple backends in the future drivers

libraries/AP_ADSB/AP_ADSB.cpp

@@ -50,12 +50,12 @@ AP_ADSB *AP_ADSB::_singleton;
 
 // table of user settable parameters
 const AP_Param::GroupInfo AP_ADSB::var_info[] = {
-    // @Param: ENABLE
-    // @DisplayName: Enable ADSB
-    // @Description: Enable ADS-B
-    // @Values: 0:Disabled,1:Enabled
+    // @Param: TYPE
+    // @DisplayName: ADSB Type
+    // @Description: Type of ADS-B hardware for ADSB-in and ADSB-out configuration and operation. If any type is selected then MAVLink based ADSB-in messages will always be enabled
+    // @Values: 0:Disabled,1:uAvionix-MAVLink
     // @User: Standard
-    AP_GROUPINFO_FLAGS("ENABLE",     0, AP_ADSB, _enabled,    0, AP_PARAM_FLAG_ENABLE),
+    AP_GROUPINFO_FLAGS("TYPE",     0, AP_ADSB, _type[0],    0, AP_PARAM_FLAG_ENABLE),
 
     // index 1 is reserved - was BEHAVIOR
 
@@ -194,17 +194,24 @@ void AP_ADSB::init(void)
         in_state.list_size_allocated = in_state.list_size_param;
     }
 
-    if (_backend == nullptr) {
-        _backend = new AP_ADSB_uAvionix_MAVLink(*this);
-
-        if (_backend == nullptr) {
-            _init_failed = true;
-            gcs().send_text(MAV_SEVERITY_CRITICAL, "ADSB: Unable to initialize ADSB driver");
-            return;
+    if (detected_num_instances == 0) {
+        for (uint8_t i=0; i<ADSB_MAX_INSTANCES; i++) {
+            detect_instance(i);
+            if (_backend[i] != nullptr) {
+                // we loaded a driver for this instance, so it must be
+                // present (although it may not be healthy)
+                detected_num_instances = i+1;
+            }
         }
     }
+
+    if (detected_num_instances == 0) {
+        _init_failed = true;
+        gcs().send_text(MAV_SEVERITY_CRITICAL, "ADSB: Unable to initialize ADSB driver");
+    }
 }
 
+
 /*
  * de-initialize and free up some memory
  */
@@ -214,11 +221,26 @@ void AP_ADSB::deinit(void)
         delete [] in_state.vehicle_list;
         in_state.vehicle_list = nullptr;
     }
+    for (uint8_t i=0; i<ADSB_MAX_INSTANCES; i++) {
+        if (_backend[i] != nullptr) {
+            delete _backend[i];
+            _backend[i] = nullptr;
+        }
+    }
+    detected_num_instances = 0;
 }
 
 bool AP_ADSB::check_startup()
 {
-    if (!_enabled || _init_failed) {
+    bool all_backends_disabled = true;
+    for (uint8_t instance=0; instance<ADSB_MAX_INSTANCES; instance++) {
+        if (_type[instance] > 0) {
+            all_backends_disabled = false;
+            break;
+        }
+    }
+
+    if (all_backends_disabled || _init_failed) {
         if (in_state.vehicle_list != nullptr) {
             deinit();
         }
@@ -231,6 +253,31 @@ bool AP_ADSB::check_startup()
     return in_state.vehicle_list != nullptr;
 }
 
+
+//  detect if an instance of an ADSB sensor is connected.
+void AP_ADSB::detect_instance(uint8_t instance)
+{
+    switch (get_type(instance)) {
+    case Type::None:
+        return;
+    case Type::uAvionix_MAVLink:
+        if (AP_ADSB_uAvionix_MAVLink::detect()) {
+            _backend[instance] = new AP_ADSB_uAvionix_MAVLink(*this, instance);
+            return;
+        }
+        break;
+    }
+}
+
+// get instance type from instance
+AP_ADSB::Type AP_ADSB::get_type(uint8_t instance) const
+{
+    if (instance < ADSB_MAX_INSTANCES) {
+        return (Type)(_type[instance].get());
+    }
+    return Type::None;
+}
+
 bool AP_ADSB::is_valid_callsign(uint16_t octal)
 {
     // treat "octal" as decimal and test if any decimal digit is > 7
@@ -311,9 +358,12 @@ void AP_ADSB::update(void)
         out_state.last_config_ms = 0; // send now
     }
 
-    if (_backend != nullptr) {
-        _backend->update();
+    for (uint8_t i=0; i<detected_num_instances; i++) {
+        if (_backend[i] != nullptr) {
+            _backend[i]->update();
+        }
     }
+
 }
 
 /*

libraries/AP_ADSB/AP_ADSB.h

@@ -34,6 +34,8 @@
 #include <AP_Common/Location.h>
 #include <GCS_MAVLink/GCS_MAVLink.h>
 
+#define ADSB_MAX_INSTANCES             1   // Maximum number of ADSB sensor instances available on this platform
+
 class AP_ADSB_Backend;
 
 class AP_ADSB {
@@ -53,6 +55,12 @@ public:
         return _singleton;
     }
 
+    // ADSB driver types
+    enum class Type {
+        None                = 0,
+        uAvionix_MAVLink    = 1,
+    };
+
     struct adsb_vehicle_t {
         mavlink_adsb_vehicle_t info; // the whole mavlink struct with all the juicy details. sizeof() == 38
         uint32_t last_update_ms; // last time this was refreshed, allows timeouts
@@ -92,8 +100,14 @@ public:
     // extract a location out of a vehicle item
     Location get_location(const adsb_vehicle_t &vehicle) const;
 
+    // ADSB is considered enabled if there are any configured backends
     bool enabled() const {
-        return _enabled;
+        for (uint8_t instance=0; instance<detected_num_instances; instance++) {
+            if (_type[instance] > 0) {
+                return true;
+            }
+        }
+        return false;
     }
 
     bool init_failed() const {
@@ -122,6 +136,8 @@ public:
     // confirm a value is a valid callsign
     static bool is_valid_callsign(uint16_t octal) WARN_IF_UNUSED;
 
+    AP_ADSB::Type get_type(uint8_t instance) const;
+
 private:
     static AP_ADSB *_singleton;
 
@@ -155,7 +171,9 @@ private:
     // mavlink handler
     void handle_transceiver_report(const mavlink_channel_t chan, const mavlink_uavionix_adsb_transceiver_health_report_t &packet);
 
-    AP_Int8     _enabled;
+    void detect_instance(uint8_t instance);
+
+    AP_Int8 _type[ADSB_MAX_INSTANCES];
 
     Location  _my_loc;
 
@@ -211,6 +229,7 @@ private:
 
     } out_state;
 
+    uint8_t detected_num_instances;
 
     // special ICAO of interest that ignored filters when != 0
     AP_Int32 _special_ICAO_target;
@@ -230,7 +249,7 @@ private:
     };
 
     // reference to backend
-    AP_ADSB_Backend *_backend;
+    AP_ADSB_Backend *_backend[ADSB_MAX_INSTANCES];
 };
 
 namespace AP {

libraries/AP_ADSB/AP_ADSB_Backend.cpp

@@ -20,8 +20,9 @@
 /*
   base class constructor.
 */
-AP_ADSB_Backend::AP_ADSB_Backend(AP_ADSB &frontend) :
-    _frontend(frontend)
+AP_ADSB_Backend::AP_ADSB_Backend(AP_ADSB &frontend, uint8_t instance) :
+    _frontend(frontend),
+    _instance(instance)
 {
 }
 

libraries/AP_ADSB/AP_ADSB_Backend.h

@@ -21,16 +21,21 @@ class AP_ADSB_Backend
 {
 public:
     // constructor.
-    AP_ADSB_Backend(AP_ADSB &frontend);
+    AP_ADSB_Backend(AP_ADSB &frontend, uint8_t instance);
 
+    // we declare a virtual destructor so that ADSB drivers can
+    // override with a custom destructor if need be
+    virtual ~AP_ADSB_Backend(void) {}
+
+    // static detection function
+    static bool detect();
 
     virtual void update() = 0;
 protected:
 
+    uint8_t _instance;
+
     // references
     AP_ADSB &_frontend;
-
-private:
-
 };
 #endif // HAL_ADSB_ENABLED

libraries/AP_ADSB/AP_ADSB_uAvionix_MAVLink.cpp

@@ -15,7 +15,7 @@
 
 #include "AP_ADSB_uAvionix_MAVLink.h"
 
-#if HAL_ADSB_ENABLED
+#if HAL_ADSB_UAVIONIX_MAVLINK_ENABLED
 #include <stdio.h>  // for sprintf
 #include <limits.h>
 #include <GCS_MAVLink/GCS.h>
@@ -31,6 +31,14 @@
 
 extern const AP_HAL::HAL& hal;
 
+// detect if an port is configured as MAVLink
+bool AP_ADSB_uAvionix_MAVLink::detect()
+{
+    // this actually requires SerialProtocol_MAVLink or SerialProtocol_MAVLink2 but
+    // we can't have a running system with that, so its safe to assume it's already defined
+    return true;
+}
+
 void AP_ADSB_uAvionix_MAVLink::update()
 {
     const uint32_t now = AP_HAL::millis();

libraries/AP_ADSB/AP_ADSB_uAvionix_MAVLink.h

@@ -17,13 +17,20 @@
 
 #include "AP_ADSB_Backend.h"
 
-#if HAL_ADSB_ENABLED
+#ifndef HAL_ADSB_UAVIONIX_MAVLINK_ENABLED
+#define HAL_ADSB_UAVIONIX_MAVLINK_ENABLED HAL_ADSB_ENABLED
+#endif
+
+#if HAL_ADSB_UAVIONIX_MAVLINK_ENABLED
 class AP_ADSB_uAvionix_MAVLink : public AP_ADSB_Backend {
 public:
     using AP_ADSB_Backend::AP_ADSB_Backend;
 
     void update() override;
 
+    // static detection function
+    static bool detect();
+
 private:
     // send static and dynamic data to ADSB transceiver
     void send_configure(const mavlink_channel_t chan);