diff --git a/libraries/AP_Proximity/AP_Proximity.cpp b/libraries/AP_Proximity/AP_Proximity.cpp
index 5e107b4e30..306751e617 100644
--- a/libraries/AP_Proximity/AP_Proximity.cpp
+++ b/libraries/AP_Proximity/AP_Proximity.cpp
@@ -178,8 +178,7 @@ const AP_Param::GroupInfo AP_Proximity::var_info[] = {
     AP_GROUPEND
 };
 
-AP_Proximity::AP_Proximity(AP_SerialManager &_serial_manager) :
-    serial_manager(_serial_manager)
+AP_Proximity::AP_Proximity()
 {
     AP_Param::setup_object_defaults(this, var_info);
 #if CONFIG_HAL_BOARD == HAL_BOARD_SITL
@@ -284,16 +283,16 @@ void AP_Proximity::detect_instance(uint8_t instance)
 {
     uint8_t type = _type[instance];
     if (type == Proximity_Type_SF40C) {
-        if (AP_Proximity_LightWareSF40C::detect(serial_manager)) {
+        if (AP_Proximity_LightWareSF40C::detect()) {
             state[instance].instance = instance;
-            drivers[instance] = new AP_Proximity_LightWareSF40C(*this, state[instance], serial_manager);
+            drivers[instance] = new AP_Proximity_LightWareSF40C(*this, state[instance]);
             return;
         }
     }
     if (type == Proximity_Type_RPLidarA2) {
-        if (AP_Proximity_RPLidarA2::detect(serial_manager)) {
+        if (AP_Proximity_RPLidarA2::detect()) {
             state[instance].instance = instance;
-            drivers[instance] = new AP_Proximity_RPLidarA2(*this, state[instance], serial_manager);
+            drivers[instance] = new AP_Proximity_RPLidarA2(*this, state[instance]);
             return;
         }
     }
@@ -303,16 +302,16 @@ void AP_Proximity::detect_instance(uint8_t instance)
         return;
     }
     if (type == Proximity_Type_TRTOWER) {
-        if (AP_Proximity_TeraRangerTower::detect(serial_manager)) {
+        if (AP_Proximity_TeraRangerTower::detect()) {
             state[instance].instance = instance;
-            drivers[instance] = new AP_Proximity_TeraRangerTower(*this, state[instance], serial_manager);
+            drivers[instance] = new AP_Proximity_TeraRangerTower(*this, state[instance]);
             return;
         }
     }
     if (type == Proximity_Type_TRTOWEREVO) {
-        if (AP_Proximity_TeraRangerTowerEvo::detect(serial_manager)) {
+        if (AP_Proximity_TeraRangerTowerEvo::detect()) {
             state[instance].instance = instance;
-            drivers[instance] = new AP_Proximity_TeraRangerTowerEvo(*this, state[instance], serial_manager);
+            drivers[instance] = new AP_Proximity_TeraRangerTowerEvo(*this, state[instance]);
             return;
         }
     }
diff --git a/libraries/AP_Proximity/AP_Proximity.h b/libraries/AP_Proximity/AP_Proximity.h
index 5055ccddb3..2ead768cfe 100644
--- a/libraries/AP_Proximity/AP_Proximity.h
+++ b/libraries/AP_Proximity/AP_Proximity.h
@@ -18,7 +18,6 @@
 #include <AP_HAL/AP_HAL.h>
 #include <AP_Param/AP_Param.h>
 #include <AP_Math/AP_Math.h>
-#include <AP_SerialManager/AP_SerialManager.h>
 #include <AP_RangeFinder/AP_RangeFinder.h>
 
 #define PROXIMITY_MAX_INSTANCES             1   // Maximum number of proximity sensor instances available on this platform
@@ -33,7 +32,7 @@ class AP_Proximity
 public:
     friend class AP_Proximity_Backend;
 
-    AP_Proximity(AP_SerialManager &_serial_manager);
+    AP_Proximity();
 
     AP_Proximity(const AP_Proximity &other) = delete;
     AP_Proximity &operator=(const AP_Proximity) = delete;
@@ -149,7 +148,6 @@ private:
     const RangeFinder *_rangefinder;
     uint8_t primary_instance;
     uint8_t num_instances;
-    AP_SerialManager &serial_manager;
 
     // parameters for all instances
     AP_Int8  _type[PROXIMITY_MAX_INSTANCES];
diff --git a/libraries/AP_Proximity/AP_Proximity_LightWareSF40C.cpp b/libraries/AP_Proximity/AP_Proximity_LightWareSF40C.cpp
index 9fc1e3cf64..32c4e2af95 100644
--- a/libraries/AP_Proximity/AP_Proximity_LightWareSF40C.cpp
+++ b/libraries/AP_Proximity/AP_Proximity_LightWareSF40C.cpp
@@ -27,10 +27,10 @@ extern const AP_HAL::HAL& hal;
    already know that we should setup the proximity sensor
 */
 AP_Proximity_LightWareSF40C::AP_Proximity_LightWareSF40C(AP_Proximity &_frontend,
-                                                         AP_Proximity::Proximity_State &_state,
-                                                         AP_SerialManager &serial_manager) :
+                                                         AP_Proximity::Proximity_State &_state) :
     AP_Proximity_Backend(_frontend, _state)
 {
+    const AP_SerialManager &serial_manager = AP::serialmanager();
     uart = serial_manager.find_serial(AP_SerialManager::SerialProtocol_Lidar360, 0);
     if (uart != nullptr) {
         uart->begin(serial_manager.find_baudrate(AP_SerialManager::SerialProtocol_Lidar360, 0));
@@ -38,9 +38,9 @@ AP_Proximity_LightWareSF40C::AP_Proximity_LightWareSF40C(AP_Proximity &_frontend
 }
 
 // detect if a Lightware proximity sensor is connected by looking for a configured serial port
-bool AP_Proximity_LightWareSF40C::detect(AP_SerialManager &serial_manager)
+bool AP_Proximity_LightWareSF40C::detect()
 {
-    return serial_manager.find_serial(AP_SerialManager::SerialProtocol_Lidar360, 0) != nullptr;
+    return AP::serialmanager().find_serial(AP_SerialManager::SerialProtocol_Lidar360, 0) != nullptr;
 }
 
 // update the state of the sensor
diff --git a/libraries/AP_Proximity/AP_Proximity_LightWareSF40C.h b/libraries/AP_Proximity/AP_Proximity_LightWareSF40C.h
index 562960a486..ce1a076435 100644
--- a/libraries/AP_Proximity/AP_Proximity_LightWareSF40C.h
+++ b/libraries/AP_Proximity/AP_Proximity_LightWareSF40C.h
@@ -10,10 +10,11 @@ class AP_Proximity_LightWareSF40C : public AP_Proximity_Backend
 
 public:
     // constructor
-    AP_Proximity_LightWareSF40C(AP_Proximity &_frontend, AP_Proximity::Proximity_State &_state, AP_SerialManager &serial_manager);
+    AP_Proximity_LightWareSF40C(AP_Proximity &_frontend,
+                                AP_Proximity::Proximity_State &_state);
 
     // static detection function
-    static bool detect(AP_SerialManager &serial_manager);
+    static bool detect();
 
     // update state
     void update(void) override;
diff --git a/libraries/AP_Proximity/AP_Proximity_RPLidarA2.cpp b/libraries/AP_Proximity/AP_Proximity_RPLidarA2.cpp
index a8ebaac088..171ad9685c 100644
--- a/libraries/AP_Proximity/AP_Proximity_RPLidarA2.cpp
+++ b/libraries/AP_Proximity/AP_Proximity_RPLidarA2.cpp
@@ -69,11 +69,12 @@ extern const AP_HAL::HAL& hal;
    constructor is not called until detect() returns true, so we
    already know that we should setup the proximity sensor
  */
-AP_Proximity_RPLidarA2::AP_Proximity_RPLidarA2(AP_Proximity &_frontend,
-                                               AP_Proximity::Proximity_State &_state,
-                                               AP_SerialManager &serial_manager) :
-                                               AP_Proximity_Backend(_frontend, _state)
+AP_Proximity_RPLidarA2::AP_Proximity_RPLidarA2(
+    AP_Proximity &_frontend,
+    AP_Proximity::Proximity_State &_state) :
+    AP_Proximity_Backend(_frontend, _state)
 {
+    const AP_SerialManager &serial_manager = AP::serialmanager();
     _uart = serial_manager.find_serial(AP_SerialManager::SerialProtocol_Lidar360, 0);
     if (_uart != nullptr) {
         _uart->begin(serial_manager.find_baudrate(AP_SerialManager::SerialProtocol_Lidar360, 0));
@@ -84,9 +85,9 @@ AP_Proximity_RPLidarA2::AP_Proximity_RPLidarA2(AP_Proximity &_frontend,
 }
 
 // detect if a RPLidarA2 proximity sensor is connected by looking for a configured serial port
-bool AP_Proximity_RPLidarA2::detect(AP_SerialManager &serial_manager)
+bool AP_Proximity_RPLidarA2::detect()
 {
-    return serial_manager.find_serial(AP_SerialManager::SerialProtocol_Lidar360, 0) != nullptr;
+    return AP::serialmanager().find_serial(AP_SerialManager::SerialProtocol_Lidar360, 0) != nullptr;
 }
 
 // update the _rp_state of the sensor
diff --git a/libraries/AP_Proximity/AP_Proximity_RPLidarA2.h b/libraries/AP_Proximity/AP_Proximity_RPLidarA2.h
index d75936e381..26a2648701 100644
--- a/libraries/AP_Proximity/AP_Proximity_RPLidarA2.h
+++ b/libraries/AP_Proximity/AP_Proximity_RPLidarA2.h
@@ -39,10 +39,10 @@ class AP_Proximity_RPLidarA2 : public AP_Proximity_Backend
 
 public:
     // constructor
-    AP_Proximity_RPLidarA2(AP_Proximity &_frontend, AP_Proximity::Proximity_State &_state, AP_SerialManager &serial_manager);
+    AP_Proximity_RPLidarA2(AP_Proximity &_frontend, AP_Proximity::Proximity_State &_state);
 
     // static detection function
-    static bool detect(AP_SerialManager &serial_manager);
+    static bool detect();
 
     // update state
     void update(void) override;
diff --git a/libraries/AP_Proximity/AP_Proximity_TeraRangerTower.cpp b/libraries/AP_Proximity/AP_Proximity_TeraRangerTower.cpp
index a8b31faf55..4b1dc9e806 100644
--- a/libraries/AP_Proximity/AP_Proximity_TeraRangerTower.cpp
+++ b/libraries/AP_Proximity/AP_Proximity_TeraRangerTower.cpp
@@ -27,11 +27,13 @@ extern const AP_HAL::HAL& hal;
    constructor is not called until detect() returns true, so we
    already know that we should setup the proximity sensor
 */
-AP_Proximity_TeraRangerTower::AP_Proximity_TeraRangerTower(AP_Proximity &_frontend,
-                                                         AP_Proximity::Proximity_State &_state,
-                                                         AP_SerialManager &serial_manager) :
+AP_Proximity_TeraRangerTower::AP_Proximity_TeraRangerTower(
+    AP_Proximity &_frontend,
+    AP_Proximity::Proximity_State &_state) :
     AP_Proximity_Backend(_frontend, _state)
 {
+    const AP_SerialManager &serial_manager = AP::serialmanager();
+
     uart = serial_manager.find_serial(AP_SerialManager::SerialProtocol_Lidar360, 0);
     if (uart != nullptr) {
         uart->begin(serial_manager.find_baudrate(AP_SerialManager::SerialProtocol_Lidar360, 0));
@@ -39,10 +41,10 @@ AP_Proximity_TeraRangerTower::AP_Proximity_TeraRangerTower(AP_Proximity &_fronte
 }
 
 // detect if a TeraRanger Tower proximity sensor is connected by looking for a configured serial port
-bool AP_Proximity_TeraRangerTower::detect(AP_SerialManager &serial_manager)
+bool AP_Proximity_TeraRangerTower::detect()
 {
     AP_HAL::UARTDriver *uart = nullptr;
-    uart = serial_manager.find_serial(AP_SerialManager::SerialProtocol_Lidar360, 0);
+    uart = AP::serialmanager().find_serial(AP_SerialManager::SerialProtocol_Lidar360, 0);
     return uart != nullptr;
 }
 
diff --git a/libraries/AP_Proximity/AP_Proximity_TeraRangerTower.h b/libraries/AP_Proximity/AP_Proximity_TeraRangerTower.h
index 880a849850..5449382fa9 100644
--- a/libraries/AP_Proximity/AP_Proximity_TeraRangerTower.h
+++ b/libraries/AP_Proximity/AP_Proximity_TeraRangerTower.h
@@ -10,10 +10,10 @@ class AP_Proximity_TeraRangerTower : public AP_Proximity_Backend
 
 public:
     // constructor
-    AP_Proximity_TeraRangerTower(AP_Proximity &_frontend, AP_Proximity::Proximity_State &_state, AP_SerialManager &serial_manager);
+    AP_Proximity_TeraRangerTower(AP_Proximity &_frontend, AP_Proximity::Proximity_State &_state);
 
     // static detection function
-    static bool detect(AP_SerialManager &serial_manager);
+    static bool detect();
 
     // update state
     void update(void) override;
diff --git a/libraries/AP_Proximity/AP_Proximity_TeraRangerTowerEvo.cpp b/libraries/AP_Proximity/AP_Proximity_TeraRangerTowerEvo.cpp
index 0da1d247a6..5672f7bacc 100644
--- a/libraries/AP_Proximity/AP_Proximity_TeraRangerTowerEvo.cpp
+++ b/libraries/AP_Proximity/AP_Proximity_TeraRangerTowerEvo.cpp
@@ -28,10 +28,11 @@ extern const AP_HAL::HAL& hal;
    already know that we should setup the proximity sensor
 */
 AP_Proximity_TeraRangerTowerEvo::AP_Proximity_TeraRangerTowerEvo(AP_Proximity &_frontend,
-                                                         AP_Proximity::Proximity_State &_state,
-                                                         AP_SerialManager &serial_manager) :
+                                                         AP_Proximity::Proximity_State &_state) :
     AP_Proximity_Backend(_frontend, _state)
 {
+    const AP_SerialManager &serial_manager = AP::serialmanager();
+
     uart = serial_manager.find_serial(AP_SerialManager::SerialProtocol_Lidar360, 0);
     if (uart != nullptr) {
         uart->begin(serial_manager.find_baudrate(AP_SerialManager::SerialProtocol_Lidar360, 0));
@@ -40,11 +41,9 @@ AP_Proximity_TeraRangerTowerEvo::AP_Proximity_TeraRangerTowerEvo(AP_Proximity &_
 }
 
 // detect if a TeraRanger Tower proximity sensor is connected by looking for a configured serial port
-bool AP_Proximity_TeraRangerTowerEvo::detect(AP_SerialManager &serial_manager)
+bool AP_Proximity_TeraRangerTowerEvo::detect()
 {
-    AP_HAL::UARTDriver *uart = nullptr;
-    uart = serial_manager.find_serial(AP_SerialManager::SerialProtocol_Lidar360, 0);
-    return uart != nullptr;
+    return (AP::serialmanager().find_serial(AP_SerialManager::SerialProtocol_Lidar360, 0) != nullptr);
 }
 
 // update the state of the sensor
diff --git a/libraries/AP_Proximity/AP_Proximity_TeraRangerTowerEvo.h b/libraries/AP_Proximity/AP_Proximity_TeraRangerTowerEvo.h
index e886542500..e2dafc797c 100644
--- a/libraries/AP_Proximity/AP_Proximity_TeraRangerTowerEvo.h
+++ b/libraries/AP_Proximity/AP_Proximity_TeraRangerTowerEvo.h
@@ -9,10 +9,10 @@ class AP_Proximity_TeraRangerTowerEvo : public AP_Proximity_Backend {
 
 public:
     // constructor
-    AP_Proximity_TeraRangerTowerEvo(AP_Proximity &_frontend, AP_Proximity::Proximity_State &_state, AP_SerialManager &serial_manager);
+    AP_Proximity_TeraRangerTowerEvo(AP_Proximity &_frontend, AP_Proximity::Proximity_State &_state);
 
     // static detection function
-    static bool detect(AP_SerialManager &serial_manager);
+    static bool detect();
 
     // update state
     void update(void) override;