AP_Baro: added ExternalAHRS backend

libraries/AP_Baro/AP_Baro.cpp

@@ -47,6 +47,7 @@
 #include "AP_Baro_UAVCAN.h"
 #endif
 #include "AP_Baro_MSP.h"
+#include "AP_Baro_ExternalAHRS.h"
 
 #include <AP_Airspeed/AP_Airspeed.h>
 #include <AP_AHRS/AP_AHRS.h>
@@ -538,6 +539,12 @@ void AP_Baro::init(void)
     }
 #endif
 
+#if HAL_EXTERNAL_AHRS_ENABLED
+    if (int8_t serial_port = AP::externalAHRS().get_port() >= 0) {
+        ADD_BACKEND(new AP_Baro_ExternalAHRS(*this, serial_port));
+    }
+#endif
+
 // macro for use by HAL_INS_PROBE_LIST
 #define GET_I2C_DEVICE(bus, address) hal.i2c_mgr->get_device(bus, address)
 
@@ -956,6 +963,18 @@ void AP_Baro::handle_msp(const MSP::msp_baro_data_message_t &pkt)
 }
 #endif 
 
+#if HAL_EXTERNAL_AHRS_ENABLED
+/*
+  handle ExternalAHRS barometer data
+ */
+void AP_Baro::handle_external(const AP_ExternalAHRS::baro_data_message_t &pkt)
+{
+    for (uint8_t i=0; i<_num_drivers; i++) {
+        drivers[i]->handle_external(pkt);
+    }
+}
+#endif 
+
 namespace AP {
 
 AP_Baro &baro()

libraries/AP_Baro/AP_Baro.h

@@ -5,6 +5,7 @@
 #include <Filter/Filter.h>
 #include <Filter/DerivativeFilter.h>
 #include <AP_MSP/msp.h>
+#include <AP_ExternalAHRS/AP_ExternalAHRS.h>
 
 #ifndef HAL_MSP_BARO_ENABLED
 #define HAL_MSP_BARO_ENABLED HAL_MSP_SENSORS_ENABLED
@@ -205,6 +206,10 @@ public:
     void handle_msp(const MSP::msp_baro_data_message_t &pkt);
 #endif
 
+#if HAL_EXTERNAL_AHRS_ENABLED
+    void handle_external(const AP_ExternalAHRS::baro_data_message_t &pkt);
+#endif
+    
 private:
     // singleton
     static AP_Baro *_singleton;

libraries/AP_Baro/AP_Baro_Backend.h

@@ -28,6 +28,10 @@ public:
     virtual void handle_msp(const MSP::msp_baro_data_message_t &pkt) {}
 #endif 
 
+#if HAL_EXTERNAL_AHRS_ENABLED
+    virtual void handle_external(const AP_ExternalAHRS::baro_data_message_t &pkt) {}
+#endif 
+    
     /*
       device driver IDs. These are used to fill in the devtype field
       of the device ID, which shows up as BARO_DEVID* parameters to

libraries/AP_Baro/AP_Baro_ExternalAHRS.cpp

@@ -0,0 +1,35 @@
+#include "AP_Baro_ExternalAHRS.h"
+
+#if HAL_EXTERNAL_AHRS_ENABLED
+
+AP_Baro_ExternalAHRS::AP_Baro_ExternalAHRS(AP_Baro &baro, uint8_t port) :
+    AP_Baro_Backend(baro)
+{
+    instance = _frontend.register_sensor();
+    set_bus_id(instance, AP_HAL::Device::make_bus_id(AP_HAL::Device::BUS_TYPE_SERIAL,port,0,0));
+}
+
+// Read the sensor
+void AP_Baro_ExternalAHRS::update(void)
+{
+    if (count) {
+        WITH_SEMAPHORE(_sem);
+        _copy_to_frontend(instance, sum_pressure/count, sum_temp/count);
+        sum_pressure = sum_temp = 0;
+        count = 0;
+    }
+}
+
+void AP_Baro_ExternalAHRS::handle_external(const AP_ExternalAHRS::baro_data_message_t &pkt)
+{
+    if (pkt.instance != 0) {
+        // not for us
+        return;
+    }
+    WITH_SEMAPHORE(_sem);
+    sum_pressure += pkt.pressure_pa;
+    sum_temp += pkt.temperature;
+    count++;
+}
+
+#endif // HAL_EXTERNAL_AHRS_ENABLED

libraries/AP_Baro/AP_Baro_ExternalAHRS.h

@@ -0,0 +1,25 @@
+/*
+  ExternalAHRS backend barometer
+ */
+#pragma once
+
+#include "AP_Baro_Backend.h"
+
+#if HAL_EXTERNAL_AHRS_ENABLED
+
+class AP_Baro_ExternalAHRS : public AP_Baro_Backend
+{
+public:
+    AP_Baro_ExternalAHRS(AP_Baro &baro, uint8_t serial_port);
+    void update(void) override;
+    void handle_external(const AP_ExternalAHRS::baro_data_message_t &pkt) override;
+
+private:
+    uint8_t instance;
+    float sum_pressure;
+    float sum_temp;
+    uint16_t count;
+};
+
+#endif // HAL_EXTERNAL_AHRS_ENABLED
+

libraries/AP_HAL/Device.h

@@ -33,6 +33,7 @@ public:
         BUS_TYPE_UAVCAN  = 3,
         BUS_TYPE_SITL    = 4,
         BUS_TYPE_MSP     = 5,
+        BUS_TYPE_SERIAL  = 6,
     };
 
     enum Speed {