AP_BattMonitor: Maxell battery on any I2C bus

libraries/AP_BattMonitor/AP_BattMonitor.cpp

@@ -115,12 +115,12 @@ AP_BattMonitor::init()
 #if HAL_BATTMON_SMBUS_ENABLE
             case AP_BattMonitor_Params::BattMonitor_TYPE_SOLO:
                 drivers[instance] = new AP_BattMonitor_SMBus_Solo(*this, state[instance], _params[instance],
-                                                                  hal.i2c_mgr->get_device(AP_BATTMONITOR_SMBUS_BUS_INTERNAL, AP_BATTMONITOR_SMBUS_I2C_ADDR,
+                                                                  hal.i2c_mgr->get_device(_params[instance]._i2c_bus, AP_BATTMONITOR_SMBUS_I2C_ADDR,
                                                                                           100000, true, 20));
                 break;
             case AP_BattMonitor_Params::BattMonitor_TYPE_MAXELL:
                 drivers[instance] = new AP_BattMonitor_SMBus_Maxell(*this, state[instance], _params[instance],
-                                                                    hal.i2c_mgr->get_device(AP_BATTMONITOR_SMBUS_BUS_EXTERNAL, AP_BATTMONITOR_SMBUS_I2C_ADDR,
+                                                                    hal.i2c_mgr->get_device(_params[instance]._i2c_bus, AP_BATTMONITOR_SMBUS_I2C_ADDR,
                                                                                             100000, true, 20));
                 break;
 #endif // HAL_BATTMON_SMBUS_ENABLE

libraries/AP_BattMonitor/AP_BattMonitor_Params.cpp

@@ -162,6 +162,13 @@ const AP_Param::GroupInfo AP_BattMonitor_Params::var_info[] = {
     // @User: Advanced
     AP_GROUPINFO("ARM_MAH", 19, AP_BattMonitor_Params, _arming_minimum_capacity, 0),
 
+    // @Param: BUS
+    // @DisplayName: Battery monitor I2C bus number
+    // @Description: Battery monitor I2C bus number
+    // @Range: 0 3
+    // @User: Standard
+    AP_GROUPINFO("BUS", 20, AP_BattMonitor_Params, _i2c_bus, 0),
+
     AP_GROUPEND
 
 };

libraries/AP_BattMonitor/AP_BattMonitor_Params.h

@@ -55,5 +55,5 @@ public:
     AP_Int8  _failsafe_critical_action; /// action to preform on a critical battery failsafe
     AP_Int32 _arming_minimum_capacity;  /// capacity level required to arm
     AP_Float _arming_minimum_voltage;   /// voltage level required to arm
-
+    AP_Int8  _i2c_bus;                  /// I2C bus number
 };