Application of MDK project macro definition

This macro definition refers to the macro definition under the project's Options window--"C/C++"--"Preprocerssor Symbols".

Here the macro definition allows the compiler to selectively compile certain codes. For example:

#if defined(LCD_MODEL_AT043)

    #define C_GLCD_H_PULSE 41

    #define C_GLCD_H_FRONT_PORCH 10

    #define C_GLCD_H_BACK_PORCH 10

    #define C_GLCD_V_PULSE 10

    #define C_GLCD_V_FRONT_PORCH 2

    #define C_GLCD_V_BACK_PORCH 2

#elif defined(LCD_MODEL_AT070)

    #define C_GLCD_H_PULSE 20

    #define C_GLCD_H_FRONT_PORCH 210

    #define C_GLCD_H_BACK_PORCH 46

    #define C_GLCD_V_PULSE 10

    #define C_GLCD_V_FRONT_PORCH 22

    #define C_GLCD_V_BACK_PORCH 23

#else

    #define C_GLCD_H_PULSE 20

    #define C_GLCD_H_FRONT_PORCH 250

    #define C_GLCD_H_BACK_PORCH 50

    #define C_GLCD_V_PULSE 5

    #define C_GLCD_V_FRONT_PORCH 5

    #define C_GLCD_V_BACK_PORCH 5

#endif

In the above code, because LCD_MODEL_AT043 is defined in the project's macro definition, only the following macro definitions will be compiled:

    #define C_GLCD_H_PULSE 41

    #define C_GLCD_H_FRONT_PORCH 10

    #define C_GLCD_H_BACK_PORCH 10

    #define C_GLCD_V_PULSE 10

    #define C_GLCD_V_FRONT_PORCH 2

    #define C_GLCD_V_BACK_PORCH 2

The application scenarios of this macro definition are as follows:

If your program may be used for two LCD screens: 4.3 inches and 7 inches, you can do this:

Create two project objects in the "Project Targets" under the "Manage Project Items" window (if you only created one before, you can just add another one).

At this time, when you go back to MDK, you can see two options in the drop-down box next to the download button.

This is the project object you just created.

Select the first 4.3-inch project object and add LCD_MODEL_AT043 in the project macro definition.

Select the second 7-inch project object and add LCD_MODEL_AT070 in the project macro definition.

This is done.

When you want to use the 4.3-inch screen program, select the 4.3-inch screen project object in the drop-down box, and the macro definition LCD_MODEL_AT043 will take effect, only compiling your program

#if defined(LCD_MODEL_AT043)

    #define C_GLCD_H_PULSE 41

    #define C_GLCD_H_FRONT_PORCH 10

    #define C_GLCD_H_BACK_PORCH 10

    #define C_GLCD_V_PULSE 10

    #define C_GLCD_V_FRONT_PORCH 2

    #define C_GLCD_V_BACK_PORCH 2

part.

You can also use this method to separate the debugging program from the official version of the program. When you need some debugging information during debugging, you can include it with a macro definition, such as:

#if defined(debug)

  shellSnd("It`s debuging status now!");

#endif