Allow FetchContent usage in external projects

CMakeLists.txt

@@ -174,4 +174,6 @@ add_subdirectory(source)
 add_subdirectory(tools)
 add_subdirectory(test)
 
-FetchContent_MakeAvailable(freertos_kernel cmock)
+if(NOT FREERTOS_PLUS_TCP_USE_LOCAL_FREERTOS)
+    FetchContent_MakeAvailable(freertos_kernel cmock)
+endif()

README.md

@@ -60,18 +60,20 @@ FetchContent_Declare( freertos_plus_tcp
   - this particular example supports a native and cross-compiled build option.
 
 ```cmake
-set( FREERTOS_PLUS_FAT_DEV_SUPPORT OFF CACHE BOOL "" FORCE)
 # Select the native compile PORT
-set( FREERTOS_PLUS_FAT_PORT "POSIX" CACHE STRING "" FORCE)
-# Select the cross-compile PORT
+set( FREERTOS_PLUS_TCP_NETWORK_IF "POSIX" CACHE STRING "" FORCE)
+# Or: select a cross-compile PORT
 if (CMAKE_CROSSCOMPILING)
-  # Eg. Zynq 2019_3 version of port
-  set(FREERTOS_PLUS_FAT_PORT "ZYNQ_2019_3" CACHE STRING "" FORCE)
+  # Eg. STM32Hxx version of port
+  set(FREERTOS_PLUS_TCP_NETWORK_IF "STM32HXX" CACHE STRING "" FORCE)
 endif()
 
 FetchContent_MakeAvailable(freertos_plus_tcp)
 ```
 
+If you already have FreeRTOS in your project, you may skip the fetch content by setting
+`FREERTOS_PLUS_TCP_USE_LOCAL_FREERTOS` to `ON`.
+
 ### Consuming stand-alone
 
 This repository uses [Git Submodules](https://git-scm.com/book/en/v2/Git-Tools-Submodules) to bring in dependent components.