diff --git a/libraries/AP_Baro/AP_Baro.cpp b/libraries/AP_Baro/AP_Baro.cpp
index 7cd348896e..169c875e65 100644
--- a/libraries/AP_Baro/AP_Baro.cpp
+++ b/libraries/AP_Baro/AP_Baro.cpp
@@ -50,6 +50,10 @@
  #define HAL_BARO_FILTER_DEFAULT 0 // turned off by default
 #endif
 
+#ifndef HAL_BARO_PROBE_EXT_DEFAULT
+ #define HAL_BARO_PROBE_EXT_DEFAULT 0
+#endif
+
 extern const AP_HAL::HAL& hal;
 
 // table of user settable parameters
@@ -143,6 +147,15 @@ const AP_Param::GroupInfo AP_Baro::var_info[] = {
     // @Increment: 1
     AP_GROUPINFO("FLTR_RNG", 13, AP_Baro, _filter_range, HAL_BARO_FILTER_DEFAULT),
 
+#ifdef HAL_PROBE_EXTERNAL_I2C_BAROS
+    // @Param: PROBE_EXT
+    // @DisplayName: External barometers to probe
+    // @Description: This sets which types of external i2c barometer to look for. It is a bitmask of barometer types
+    // @Bitmask: 0:BMP085,1:BMP280,2:MS5611,3:MS5607,4:MS5637,5:FBM320,6:DPS280,7:LPS25H,8:Keller
+    // @User: Advanced
+    AP_GROUPINFO("PROBE_EXT", 14, AP_Baro, _baro_probe_ext, HAL_BARO_PROBE_EXT_DEFAULT),
+#endif
+    
     AP_GROUPEND
 };
 
@@ -596,6 +609,10 @@ void AP_Baro::init(void)
 #endif
     }
 
+#ifdef HAL_PROBE_EXTERNAL_I2C_BAROS
+    _probe_i2c_barometers();
+#endif
+    
 #if CONFIG_HAL_BOARD != HAL_BOARD_F4LIGHT // most boards requires external baro
 
     if (_num_drivers == 0 || _num_sensors == 0 || drivers[0] == nullptr) {
@@ -604,6 +621,83 @@ void AP_Baro::init(void)
 #endif
 }
 
+/*
+  probe all the i2c barometers enabled with GND_PROBE_EXT. This is
+  used on boards without a builtin barometer
+ */
+void AP_Baro::_probe_i2c_barometers(void)
+{
+    uint32_t probe = _baro_probe_ext.get();
+    if (probe & PROBE_BMP085) {
+        FOREACH_I2C_EXTERNAL(i) {
+            ADD_BACKEND(AP_Baro_BMP085::probe(*this,
+                                              std::move(hal.i2c_mgr->get_device(i, HAL_BARO_BMP085_I2C_ADDR))));
+        }
+    }
+    if (probe & PROBE_BMP280) {
+        FOREACH_I2C_EXTERNAL(i) {
+            ADD_BACKEND(AP_Baro_BMP280::probe(*this,
+                                              std::move(hal.i2c_mgr->get_device(i, HAL_BARO_BMP280_I2C_ADDR))));
+            ADD_BACKEND(AP_Baro_BMP280::probe(*this,
+                                              std::move(hal.i2c_mgr->get_device(i, HAL_BARO_BMP280_I2C_ADDR2))));
+        }
+    }
+    if (probe & PROBE_MS5611) {
+        FOREACH_I2C_EXTERNAL(i) {
+            ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
+                                              std::move(hal.i2c_mgr->get_device(i, HAL_BARO_MS5611_I2C_ADDR))));
+        }
+    }
+    if (probe & PROBE_MS5607) {
+        FOREACH_I2C_EXTERNAL(i) {
+            ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
+                                              std::move(hal.i2c_mgr->get_device(i, HAL_BARO_MS5607_I2C_ADDR)),
+                                              AP_Baro_MS56XX::BARO_MS5607));
+        }
+    }
+    if (probe & PROBE_MS5637) {
+        FOREACH_I2C_EXTERNAL(i) {
+            ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
+                                              std::move(hal.i2c_mgr->get_device(i, HAL_BARO_MS5637_I2C_ADDR)),
+                                              AP_Baro_MS56XX::BARO_MS5637));
+        }
+    }
+    if (probe & PROBE_FBM320) {
+        FOREACH_I2C_EXTERNAL(i) {
+            ADD_BACKEND(AP_Baro_FBM320::probe(*this,
+                                              std::move(hal.i2c_mgr->get_device(i, HAL_BARO_FBM320_I2C_ADDR))));
+            ADD_BACKEND(AP_Baro_FBM320::probe(*this,
+                                              std::move(hal.i2c_mgr->get_device(i, HAL_BARO_FBM320_I2C_ADDR2))));
+        }
+    }
+    if (probe & PROBE_DPS280) {
+        FOREACH_I2C_EXTERNAL(i) {
+            ADD_BACKEND(AP_Baro_DPS280::probe(*this,
+                                              std::move(hal.i2c_mgr->get_device(i, HAL_BARO_DPS280_I2C_ADDR))));
+            ADD_BACKEND(AP_Baro_DPS280::probe(*this,
+                                              std::move(hal.i2c_mgr->get_device(i, HAL_BARO_DPS280_I2C_ADDR2))));
+        }
+    }
+    if (probe & PROBE_LPS25H) {
+        FOREACH_I2C_EXTERNAL(i) {
+            ADD_BACKEND(AP_Baro_LPS2XH::probe(*this,
+                                              std::move(hal.i2c_mgr->get_device(i, HAL_BARO_LPS25H_I2C_ADDR))));
+        }
+    }
+    if (probe & PROBE_LPS25H) {
+        FOREACH_I2C_EXTERNAL(i) {
+            ADD_BACKEND(AP_Baro_KellerLD::probe(*this,
+                                                std::move(hal.i2c_mgr->get_device(i, HAL_BARO_KELLERLD_I2C_ADDR))));
+        }
+    }
+    if (probe & PROBE_MS5837) {
+        FOREACH_I2C_EXTERNAL(i) {
+            ADD_BACKEND(AP_Baro_MS56XX::probe(*this,
+                                              std::move(hal.i2c_mgr->get_device(i, HAL_BARO_MS5837_I2C_ADDR)), AP_Baro_MS56XX::BARO_MS5837));
+        }
+    }
+}
+
 bool AP_Baro::should_df_log() const
 {
     DataFlash_Class *instance = DataFlash_Class::instance();
diff --git a/libraries/AP_Baro/AP_Baro.h b/libraries/AP_Baro/AP_Baro.h
index a2d67021d5..6d8abd0b22 100644
--- a/libraries/AP_Baro/AP_Baro.h
+++ b/libraries/AP_Baro/AP_Baro.h
@@ -197,6 +197,20 @@ private:
 
     uint32_t _log_baro_bit = -1;
 
+    // bitmask values for GND_PROBE_EXT
+    enum {
+        PROBE_BMP085=(1<<0),
+        PROBE_BMP280=(1<<1),
+        PROBE_MS5611=(1<<2),
+        PROBE_MS5607=(1<<3),
+        PROBE_MS5637=(1<<4),
+        PROBE_FBM320=(1<<5),
+        PROBE_DPS280=(1<<6),
+        PROBE_LPS25H=(1<<7),
+        PROBE_KELLER=(1<<8),
+        PROBE_MS5837=(1<<9),
+    };
+    
     struct sensor {
         baro_type_t type;                   // 0 for air pressure (default), 1 for water pressure
         uint32_t last_update_ms;        // last update time in ms
@@ -229,7 +243,9 @@ private:
     uint32_t                            _last_notify_ms;
 
     bool _add_backend(AP_Baro_Backend *backend);
+    void _probe_i2c_barometers(void);
     AP_Int8                            _filter_range;  // valid value range from mean value
+    AP_Int32                           _baro_probe_ext;
 };
 
 namespace AP {
diff --git a/libraries/AP_Baro/AP_Baro_BMP280.h b/libraries/AP_Baro/AP_Baro_BMP280.h
index e59d0110fe..a1075c0b08 100644
--- a/libraries/AP_Baro/AP_Baro_BMP280.h
+++ b/libraries/AP_Baro/AP_Baro_BMP280.h
@@ -7,7 +7,10 @@
 #include "AP_Baro_Backend.h"
 
 #ifndef HAL_BARO_BMP280_I2C_ADDR
- #define HAL_BARO_BMP280_I2C_ADDR (0x76)
+ #define HAL_BARO_BMP280_I2C_ADDR  (0x76)
+#endif
+#ifndef HAL_BARO_BMP280_I2C_ADDR2
+ #define HAL_BARO_BMP280_I2C_ADDR2 (0x77)
 #endif
 
 class AP_Baro_BMP280 : public AP_Baro_Backend
diff --git a/libraries/AP_Baro/AP_Baro_DPS280.h b/libraries/AP_Baro/AP_Baro_DPS280.h
index 0ea5cadbff..35c7b1c2ee 100644
--- a/libraries/AP_Baro/AP_Baro_DPS280.h
+++ b/libraries/AP_Baro/AP_Baro_DPS280.h
@@ -6,6 +6,13 @@
 
 #include "AP_Baro_Backend.h"
 
+#ifndef HAL_BARO_DPS280_I2C_ADDR
+ #define HAL_BARO_DPS280_I2C_ADDR  0x76
+#endif
+#ifndef HAL_BARO_DPS280_I2C_ADDR2
+ #define HAL_BARO_DPS280_I2C_ADDR2 0x77
+#endif
+
 class AP_Baro_DPS280 : public AP_Baro_Backend {
 public:
     AP_Baro_DPS280(AP_Baro &baro, AP_HAL::OwnPtr<AP_HAL::Device> dev);
diff --git a/libraries/AP_Baro/AP_Baro_FBM320.h b/libraries/AP_Baro/AP_Baro_FBM320.h
index 8104e4f0ec..b538d9e85c 100644
--- a/libraries/AP_Baro/AP_Baro_FBM320.h
+++ b/libraries/AP_Baro/AP_Baro_FBM320.h
@@ -6,6 +6,14 @@
 
 #include "AP_Baro_Backend.h"
 
+#ifndef HAL_BARO_FBM320_I2C_ADDR
+ #define HAL_BARO_FBM320_I2C_ADDR  0x6C
+#endif
+#ifndef HAL_BARO_FBM320_I2C_ADDR2
+ #define HAL_BARO_FBM320_I2C_ADDR2 0x6D
+#endif
+
+
 class AP_Baro_FBM320 : public AP_Baro_Backend {
 public:
     AP_Baro_FBM320(AP_Baro &baro, AP_HAL::OwnPtr<AP_HAL::Device> dev);
diff --git a/libraries/AP_Baro/AP_Baro_LPS2XH.h b/libraries/AP_Baro/AP_Baro_LPS2XH.h
index 627ceff6c7..028f17d86d 100644
--- a/libraries/AP_Baro/AP_Baro_LPS2XH.h
+++ b/libraries/AP_Baro/AP_Baro_LPS2XH.h
@@ -7,7 +7,10 @@
 #include "AP_Baro_Backend.h"
 
 #define HAL_BARO_LPS25H_I2C_BUS 0
-#define HAL_BARO_LPS25H_I2C_ADDR 0x5D
+
+#ifndef HAL_BARO_LPS25H_I2C_ADDR
+# define HAL_BARO_LPS25H_I2C_ADDR 0x5D
+#endif
 
 
 class AP_Baro_LPS2XH : public AP_Baro_Backend
diff --git a/libraries/AP_Baro/AP_Baro_MS5611.h b/libraries/AP_Baro/AP_Baro_MS5611.h
index 8f69f62060..393d048a02 100644
--- a/libraries/AP_Baro/AP_Baro_MS5611.h
+++ b/libraries/AP_Baro/AP_Baro_MS5611.h
@@ -10,10 +10,18 @@
 #define HAL_BARO_MS5611_I2C_ADDR 0x77
 #endif
 
+#ifndef HAL_BARO_MS5607_I2C_ADDR
+#define HAL_BARO_MS5607_I2C_ADDR 0x77
+#endif
+
 #ifndef HAL_BARO_MS5837_I2C_ADDR
 #define HAL_BARO_MS5837_I2C_ADDR 0x76
 #endif
 
+#ifndef HAL_BARO_MS5637_I2C_ADDR
+#define HAL_BARO_MS5637_I2C_ADDR 0x76
+#endif
+
 class AP_Baro_MS56XX : public AP_Baro_Backend
 {
 public: