How to create a safe memory in flash to store custom Data (not use Flash library of SDK)

[Giang]

Hi all,

Question 1 : 

I want to save 1 string to flash, but I don't use code for this, I have a machine and it store string to flash of NRF52832 for me. My job is to ensure a free memory area for this.

I read this link : http://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.sdk52.v0.9.0%2Fbledfu_memory.html

I want to define a free memory at Free in picture above. But the application size may change. How I can limit application memory for it do not overwrite my free memory in any case.

The size of string is 20 bytes.

Question 2 : 

I read this link : http://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.sdk52.v0.9.0%2Fbledfu_memory_banks.html

I want to question, ble_app_buttonless_dfu examble update application follow dual bank or single bank ? 

Thank for help !!

[AndreasF]

Hello.

Question 1:

You have to define a region in the free memory with an offset from the Application, read more in this ticket.

Question 2:

You don't specify if you want to use single or dual bank in the Application, this is done in the bootloader. If there is enough memory space for a dual bank update the bootloader will automatically choose dual bank, if there is not enough memory space the bootloader will choose single bank. You can also force the bootloader to choose dual bank by defining NRF_DFU_FORCE_DUAL_BANK_APP_UPDATES 1, if there is not enough space when this is defined then nothing will happen and the update will be canceled. You can read more here.

Best regards,

Andreas

[Giang]

Thank for reply,

At question 1, I use KeilC and I don't understand. Can you describe more clearly ?

[AndreasF]

Hi.

You can for example use this in your main.c file:

char dummy_block [0x400]  __attribute__((section(".ARM.__at_0x39000"))); 

Best regards,

Andreas

[Giang]

What does your code line mean?

[AndreasF]

Hi.

Giang said:

What does you code line mean?

The content of dummy_block gets written to the memory section 0x39000.

You can also use nrf_nvmc_write_word(uint32_t address, uint32_t value)

/**
 * @brief Write a 32-bit word to flash.
 * @param address Address to write to.
 * @param value   Value to write.
 */
void nrf_nvmc_write_word(uint32_t address, uint32_t value);

If you include nrf_nvic.c and nrf_nvic.h to your project.

Best regards,

Andreas