diff --git a/sdk/Windows/SMX.cpp b/sdk/Windows/SMX.cpp
index f42a2cd..4df2ac9 100644
--- a/sdk/Windows/SMX.cpp
+++ b/sdk/Windows/SMX.cpp
@@ -98,3 +98,6 @@ SMX_API void SMX_SetLights2(const char *lightData, int lightDataSize)
 }
 SMX_API void SMX_ReenableAutoLights() { SMXManager::g_pSMX->ReenableAutoLights(); }
 SMX_API const char *SMX_Version() { return SMX_BUILD_VERSION; }
+
+// This isn't exposed in the public API, since this is only used internally.
+SMX_API void SMX_SetOnlySendLightsOnChange(bool value) { SMXManager::g_pSMX->SetOnlySendLightsOnChange(value); }
diff --git a/sdk/Windows/SMXManager.cpp b/sdk/Windows/SMXManager.cpp
index fe43d70..d39388e 100644
--- a/sdk/Windows/SMXManager.cpp
+++ b/sdk/Windows/SMXManager.cpp
@@ -253,6 +253,22 @@ void SMX::SMXManager::SetLights(const string sPanelLights[2])
     if(m_PanelTestMode != PanelTestMode_Off)
         return;
 
+    // If m_bOnlySendLightsOnChange is true, only send lights commands if the lights have
+    // actually changed.  This is only used for internal testing, and the controllers normally
+    // expect to receive regular lights updates, even if the lights aren't actually changing.
+    if(m_bOnlySendLightsOnChange)
+    {
+        static string sLastPanelLights[2];
+        if(sPanelLights[0] == sLastPanelLights[0] && sPanelLights[1] == sLastPanelLights[1])
+        {
+            Log("no change");
+            return;
+        }
+
+        sLastPanelLights[0] = sPanelLights[0];
+        sLastPanelLights[1] = sPanelLights[1];
+    }
+
     // Separate top and bottom lights commands.
     //
     // sPanelLights[iPad] is
diff --git a/sdk/Windows/SMXManager.h b/sdk/Windows/SMXManager.h
index 4e4b1f7..cf64fe0 100644
--- a/sdk/Windows/SMXManager.h
+++ b/sdk/Windows/SMXManager.h
@@ -46,7 +46,8 @@ public:
     void SetLights(const string sLights[2]);
     void ReenableAutoLights();
     void SetPanelTestMode(PanelTestMode mode);
-
+    void SetOnlySendLightsOnChange(bool value) { m_bOnlySendLightsOnChange = value; }
+    
     // Run a function in the user callback thread.
     void RunInHelperThread(function<void()> func);
 
@@ -85,6 +86,8 @@ private:
     uint32_t m_SentPanelTestModeAtTicks = 0;
     PanelTestMode m_PanelTestMode = PanelTestMode_Off;
     PanelTestMode m_LastSentPanelTestMode = PanelTestMode_Off;
+
+    bool m_bOnlySendLightsOnChange = false;
 };
 }