Updated ring buffer

Updated ring buffer to match use case, one write head with negative read
index

STM32/CM7/CMakeLists.txt

@@ -59,6 +59,7 @@ target_include_directories(${CMAKE_PROJECT_NAME} PRIVATE
 # Add sources to executable
 target_sources(${CMAKE_PROJECT_NAME} PRIVATE
     # Add user sources here
+    Core/Src/ring_buffer.c
 )
 
 # Link directories setup