How to directly write the environment constant (ENV) in MDK to some built-in flash settings

Placing a key in flash memory using _

Arm compiler toolchain v5.02 for µvision using the linker

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Placing a key in flash memory using _

Some flash devices require a key to be written to an address to activate certain features.__atSection provides a simple method of writing a value to a specific address.

Assuming a device has flash memory from0x8000To0x10000And a key is required in address0x8000. To do this with__atSection, you must declare a variable so that the compiler can generate a section called.ARM.__at_0x8000.

Example 24. Placement of the flash key variable in C or C ++ code

// place flash_key in a section called .ARM.__at_0x8000long flash_key __attribute__((section(".ARM.__at_0x8000")));

The following example shows a scatter file with manual placement of the flash execution region:

Example 25. Manual placement of Flash execution regions

ER_FLASH 0x8000 0x2000{    *(+RO)    *(.ARM.__at_0x8000) ; key}

Use the linker command-line option--no_autoatTo enable manual placement.

The following example shows a scatter file with automatic placement of the flash execution region. Use the linker command-line option--autoatTo enable automatic placement.

Example 26. Automatic Placement of Flash execution regions

Er_flash 0x8000 0x2000 {* (+ RO); Other code and read-only data, the; _ at section is automatically selected}


Test:

; *************************************************************; *** Scatter-Loading Description File generated by uVision ***; *************************************************************LR_IROM1 0x08000000 0x00010000     {    ER_IROM1 0x08000000    0x0000F000   {        startup.o (RESET, +First)             .ANY (+RO)    }            ER_IROM2 0x0800F000    FIXED 0x00001000   {        main.o (.ARM.__at_0xF000)     }        RW_IRAM1 0x20000000 0x00004000  {        .ANY (+RW,+ZI)    }                                                        ;     RW_IRAM3 0x20004800 UNINIT 0x0000200   ; HEAP   {         startup.o(HEAP)   }           RW_IRAM2 0x20004A00 UNINIT 0x0000600   ; STACK   {         startup.o(STACK)   }}// main.c/* Private macro -------------------------------------------------------------*/const char buf[4096] __attribute__((section(".ARM.__at_0xF000"))) = {"Hello World!"} 

The red font is a field identifier used for indexing.

How to directly write the environment constant (ENV) in MDK to some built-in flash settings