Added README.md file

Author: abdoaboganima

README.md

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+# Structure
+
+- I used layer architecture for developing the drivers and the HALs of the atmega32 microcontroller.
+
+## Module Structure
+
+- Every folder in the `MCAL` or `HAL` folders is considered as a module.
+- Every module contains 5 files:
+	1. `MODULE_interface.h `: Contains the interface of the module like functions prototypes 
+		and structure types. 
+	2. `MODULE_program.c   `: Contains the implementations and details of the module.
+	3. `MODULE_register.h  `: A register definition file that contains registers names and their map
+		either in the microcontroller or in an external device.
+	4. `MODULE_config.h    `: Contains the pre-build configurations of the module.
+	5. `MODULE_private.h   `: Contains definitions private to the module.
+	6. `MODULE_test.c      `: Contains tests for the module only. *(Note: It has a main function.)*
+
+# How to use
+	
+	This Project has multiple main functions. We can compile source files, but can link only with one 
+	source file that has a main function.
+	
+## Options for compiling, linking, building, and flashing.
+
+1. `make compile-all` : 
+
+   Compiles all source file that has no `main` function. 
+   *(It only compiles the `_program.c` source files)*
+
+
+2. `make build-all`   : 
+   1. Compiles all source files that has no `main` function.
+   2. For every source file that has the `main` function, Compile it and Link it with other object files.
+	  Then Generate its corresponding executable. *(Usually `.elf` and `.hex` format)* 
+
+
+3. `make flash EXEC=*flash_name*`:
+   
+   Flashes the `.hex` file to the microcontroller.
+   The `EXEC` variable must be specified because we have multiple executables.
+   > (**Note**:*`flash_name` must be without any suffixes*)
+   
+   
+4. `make clean`: Cleans all the generated files.
+5. `make docs` : Generate documentation files.
+
+
+## Examples
+To build all the executables and flash the `MPU6050_test.hex`, just do as the following:
+
+```
+$ make build-all && make all EXEC=MPU6050_test
+```