CONST configuration clarification required

[vsmguy]

I did not understand this explanation:

[Ttelmah]

All 'intialised' values, _start_ in program memory (= flash = ROM). There is nowhere else to hold them. So:

char str[]="fred";

Puts 'fred' in the ROM (flash) to begin with.

Then the vaue is read during boot, and copied to RAM (since this is a RAM variable).

With 'const', using the default settings, the string is left in the ROM, and accessed there.

When you instead select 'READ_ONLY', the value is initialised into RAM, just like a RAM variable, but the 'write' functions for that variable are disabled.
You can still accidentally overwrite it, if you use pointer arithmetic, and start to access the wrong part of RAM.....

You can use the addressmod functions to place variables into EEPROM (either internal or external). Downsides, you must remember the very large time overhead associated with writing, and significant bulk to the code using this route.

If you place an array, _and never access the values in it, or only access a few values_, the compiler wll only store the values you actually access.

Best Wishes