diff --git a/libraries/AP_HAL_SITL/HAL_SITL_Class.cpp b/libraries/AP_HAL_SITL/HAL_SITL_Class.cpp
index c157472f8c..8a7537ab97 100644
--- a/libraries/AP_HAL_SITL/HAL_SITL_Class.cpp
+++ b/libraries/AP_HAL_SITL/HAL_SITL_Class.cpp
@@ -64,11 +64,11 @@ static UARTDriver sitlUart7Driver(7, &sitlState);
 static UARTDriver sitlUart8Driver(8, &sitlState);
 static UARTDriver sitlUart9Driver(9, &sitlState);
 
+static I2CDeviceManager i2c_mgr_instance;
+
 #if defined(HAL_BUILD_AP_PERIPH)
-static Empty::I2CDeviceManager i2c_mgr_instance;
 static Empty::SPIDeviceManager spi_mgr_instance;
 #else
-static I2CDeviceManager i2c_mgr_instance;
 static SPIDeviceManager spi_mgr_instance;
 #endif
 static Util utilInstance(&sitlState);
diff --git a/libraries/AP_HAL_SITL/I2CDevice.cpp b/libraries/AP_HAL_SITL/I2CDevice.cpp
index e4f789ffe0..7b7b2d5914 100644
--- a/libraries/AP_HAL_SITL/I2CDevice.cpp
+++ b/libraries/AP_HAL_SITL/I2CDevice.cpp
@@ -17,7 +17,7 @@
 #include "I2CDevice.h"
 
 #include <AP_HAL/AP_HAL.h>
-#if CONFIG_HAL_BOARD == HAL_BOARD_SITL && !defined(HAL_BUILD_AP_PERIPH)
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
 
 #include <SITL/SITL.h>
 
@@ -217,4 +217,4 @@ bool I2CDevice::adjust_periodic_callback(Device::PeriodicHandle h, uint32_t peri
     return false;
 }
 
-#endif //#if CONFIG_HAL_BOARD == HAL_BOARD_SITL && !defined(HAL_BUILD_AP_PERIPH)
+#endif //#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
diff --git a/libraries/AP_HAL_SITL/I2CDevice.h b/libraries/AP_HAL_SITL/I2CDevice.h
index 2a414bcf69..828fd3efd4 100644
--- a/libraries/AP_HAL_SITL/I2CDevice.h
+++ b/libraries/AP_HAL_SITL/I2CDevice.h
@@ -19,7 +19,7 @@
 #include <inttypes.h>
 
 #include <AP_HAL/HAL.h>
-#if CONFIG_HAL_BOARD == HAL_BOARD_SITL && !defined(HAL_BUILD_AP_PERIPH)
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
 
 #include <AP_HAL/I2CDevice.h>
 #include <AP_HAL/utility/OwnPtr.h>
@@ -128,4 +128,4 @@ protected:
     #define NUM_SITL_I2C_BUSES 4
     static I2CBus buses[];
 };
-#endif //#if CONFIG_HAL_BOARD == HAL_BOARD_SITL && !defined(HAL_BUILD_AP_PERIPH)
+#endif //#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
diff --git a/libraries/AP_HAL_SITL/SITL_Periph_State.cpp b/libraries/AP_HAL_SITL/SITL_Periph_State.cpp
index c53f84623f..a4bf8cfa1c 100644
--- a/libraries/AP_HAL_SITL/SITL_Periph_State.cpp
+++ b/libraries/AP_HAL_SITL/SITL_Periph_State.cpp
@@ -117,6 +117,9 @@ void SITL_State::init(int argc, char * const argv[]) {
     sitl_model = new SimMCast("");
 
     _sitl = AP::sitl();
+
+    _sitl->i2c_sim.init();
+    sitl_model->set_i2c(&_sitl->i2c_sim);
 }
 
 void SITL_State::wait_clock(uint64_t wait_time_usec)
@@ -285,6 +288,12 @@ SimMCast::SimMCast(const char *frame_str) :
 void SimMCast::update(const struct sitl_input &input)
 {
     multicast_read();
+    update_external_payload(input);
+
+    auto *_sitl = AP::sitl();
+    if (_sitl != nullptr) {
+        battery_voltage = _sitl->batt_voltage;
+    }
 }
 
 #endif //CONFIG_HAL_BOARD == HAL_BOARD_SITL && defined(HAL_BUILD_AP_PERIPH)
diff --git a/libraries/AP_HAL_SITL/SITL_Periph_State.h b/libraries/AP_HAL_SITL/SITL_Periph_State.h
index 17bf1c8615..e519c84c53 100644
--- a/libraries/AP_HAL_SITL/SITL_Periph_State.h
+++ b/libraries/AP_HAL_SITL/SITL_Periph_State.h
@@ -51,7 +51,7 @@ class HALSITL::SITL_State : public SITL_State_Common {
     friend class HALSITL::Util;
     friend class HALSITL::GPIO;
 public:
-    void init(int argc, char * const argv[]);
+    void init(int argc, char * const argv[]) override;
 
     bool use_rtscts(void) const {
         return _use_rtscts;
diff --git a/libraries/AP_HAL_SITL/SITL_State.h b/libraries/AP_HAL_SITL/SITL_State.h
index 1bb57e161b..8ca5afd452 100644
--- a/libraries/AP_HAL_SITL/SITL_State.h
+++ b/libraries/AP_HAL_SITL/SITL_State.h
@@ -17,7 +17,7 @@ class HALSITL::SITL_State : public SITL_State_Common {
     friend class HALSITL::Util;
     friend class HALSITL::GPIO;
 public:
-    void init(int argc, char * const argv[]);
+    void init(int argc, char * const argv[]) override;
 
     void loop_hook(void);
     uint16_t base_port(void) const {
diff --git a/libraries/AP_HAL_SITL/SITL_State_common.h b/libraries/AP_HAL_SITL/SITL_State_common.h
index 1d4555ccd9..b1105ecc35 100644
--- a/libraries/AP_HAL_SITL/SITL_State_common.h
+++ b/libraries/AP_HAL_SITL/SITL_State_common.h
@@ -73,7 +73,7 @@ class HALSITL::SITL_State_Common {
     friend class HALSITL::Util;
     friend class HALSITL::GPIO;
 public:
-    void init(int argc, char * const argv[]);
+    virtual void init(int argc, char * const argv[]) = 0;
 
     enum vehicle_type {
         NONE,
diff --git a/libraries/AP_HAL_SITL/Scheduler.cpp b/libraries/AP_HAL_SITL/Scheduler.cpp
index ba04d6af2d..2531722d71 100644
--- a/libraries/AP_HAL_SITL/Scheduler.cpp
+++ b/libraries/AP_HAL_SITL/Scheduler.cpp
@@ -276,10 +276,8 @@ void Scheduler::_run_io_procs()
     }
     hal.storage->_timer_tick();
 
-#ifndef HAL_BUILD_AP_PERIPH
     // in lieu of a thread-per-bus:
     ((HALSITL::I2CDeviceManager*)(hal.i2c_mgr))->_timer_tick();
-#endif
 
 #if SITL_STACK_CHECKING_ENABLED
     check_thread_stacks();