ST STM32F2 - Figure 7: Low Layer Driver Folders

Overview of Low Layer drivers
UM1940
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DocID028236 Rev 2
File
Description
stm32_assert_template.h
Template file allowing to define the assert_param macro, that is used
when run-time checking is enabled.
This file is required only when the LL drivers are used in standalone
mode (without calling the HAL APIs). It should be copied to the
application folder and renamed to stm32_assert.h.
There is no configuration file for the LL drivers.
The Low Layer files are located in the same HAL driver folder.
Figure 7: Low Layer driver folders
In general, Low Layer drivers include only the STM32 CMSIS device file.
#include "stm32yyxx.h"