diff --git a/bspMCU/l_stm32.c b/bspMCU/l_stm32.c
index 3ffb53d..220a064 100644
--- a/bspMCU/l_stm32.c
+++ b/bspMCU/l_stm32.c
@@ -444,6 +444,7 @@ static int l_mount (lua_State *L)
 }
 #endif
 
+#ifdef BUILD_RBCORE
 static int l_sendto(lua_State *L)
 {
 	int MsgCenter_SendTo(const char *pszDstName, uint32_t uiMsgID, const void *pData, uint32_t uiDataLen);
@@ -478,6 +479,7 @@ static int l_sendto(lua_State *L)
     lua_pushinteger(L, ret);
     return 1;
 }
+#endif
 
 #ifdef USE_ONCHIP_FLASH
 
@@ -794,7 +796,9 @@ int luaopen_stm32(lua_State *L)
     lua_register_help(L, "mount", l_mount, "mount littlefs disk");
 #endif
 
+#ifdef BUILD_RBCORE
     lua_register_help(L, "sendto", l_sendto, "Send msg: sendto(dst,id,data)");
+#endif
 
     return 1;
 }