Compiler: Store a constant variable in program memory

Marat Akhmetov

Tool/software: TI C/C++ Compiler

Hi.

I'm currently developing a ZStack application. How can I store a constant variable (an array of uint8) in a program (flash) memory and read it's value?

over 8 years ago

0 YiKai Chen over 8 years ago

Guru 735695 points

You can use API osal_nv_write and osal_nv_read to do it.

0 Marat Akhmetov over 8 years ago in reply to YiKai Chen

Intellectual 560 points

osal_nv_write and osal_nv_read store data in EEPROM, I meant to ask how to store data in code memory.

In c/c++ reference I've found __code attribute.

Will it be correct and safe to declare variable like this to store constant data in code memory?

__code const unsigned char test[] = {0x00, 0x01, ...};

0 YiKai Chen over 8 years ago in reply to Marat Akhmetov

Guru 735695 points

No, those API will write and read internal flash not EEPROM.

0 Marat Akhmetov over 8 years ago in reply to YiKai Chen

Intellectual 560 points

If using osal_nv_write the variable has to be initialized during the runtime, but I want it to be initialized during compilation.

0 YiKai Chen over 8 years ago in reply to Marat Akhmetov

Guru 735695 points

You can claim a const variable in your code and use osal_nv_write to write the const variable into internal flash when device runs first time.

0 behold li over 8 years ago

Expert 2745 points

You must define your variable with __root keyword,IAR will not "store" your variable to RAM but to flash,don't need osal_NV_write and osal_NV_read.
please search "IAR __root" keyword in google,you can get vary much result.

0 Marat Akhmetov over 8 years ago in reply to behold li

Intellectual 560 points

hold li said:
You must define your variable with __root keyword,IAR will not "store" your variable to RAM but to flash,don't need osal_NV_write and osal_NV_read.
please search "IAR __root" keyword in google,you can get vary much result.

Thanks for reply. Using __code attrubute solved my problem. __code attribute tells compiler to store variable in code memory.

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Compiler: Store a constant variable in program memory