The const keyword shall be used whenever possible, including:

    * To declare variables that should not be changed after initialization,
    * To define call-by-reference function parameters that should not be modified (for example, char const * p_data),
    * To define fields in structs and unions that cannot be modified (such as in a struct overlay for memory-mapped I/O peripheral registers), and
    * As a strongly typed alternative to #define for numerical constants.

Reasoning: The upside of using const as much as possible is compiler-enforced protection from unintended writes to data that should be read-only.

Let's think about this:

#define M_PI 3.1415926
...
M_PI = 2;

or maybe:

enum {
    MAX_COUNT = 100,
};
...
MAX_COUNT = 17;

Do you see #define or enum as having problems that requires them to require extra protection from "unintended writes to data that should be read-only"? A compiler would catch both the above situations and scream wildly.

But let's view the reverse. You have a const int, but you haven't placed it in the code segment (maybe a bug in a linker configuration file). Now you have a const variable that have an address. And if it happens to be stored in a read/write memory region that a pointer error somewhere in the program can modify your const int, suddenly making your program breaking even worse than it did from just a +/- 1 pointer access.

And the important thing: C likes a numeric value as size for an array - not an int variable (even if it happens to be const). So there can't be any universal conversion from #define or enum to const declarations.

By the way - you didn't follow rule #7 - use of uint8_t or int8_t to force the size of your constant ;)