Flash management with operative system

Question

Hello, 
 we are using nrf52840 with nrf5 sdk for thread and Zigbee v4.2.0. 
 We have been experiencing flash memory issues for a while now: https://devzone.nordicsemi.com/f/nordic-q-a/110247/issue-with-zigbee-flash-area 
 I believe that we are not managing correctly multiple access to flash memory. 
 To erase a section we use nrf_nvmc_page_erase() and to write we call nrf_nvmc_write_words() but I saw that also Zigbee stack is doing the same. This can result in one task disabling write access (and enabling erase) while the other one is trying to write, for instance. 
 Do you agree with this? Is there another API we should use? 
 void nrf_nvmc_page_erase(uint32_t address)
{
 // Enable erase.
 NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Een;
 __ISB();
 __DSB();

// Erase the page
 NRF_NVMC->ERASEPAGE = address;
 wait_for_flash_ready();

NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren;
 __ISB();
 __DSB();
}

void nrf_nvmc_write_words(uint32_t address, const uint32_t * src, uint32_t num_words)
{
 uint32_t i;

// Enable write.
 NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen;
 __ISB();
 __DSB();

for (i = 0; i < num_words; i++)
 {
 ((uint32_t*)address)[i] = src[i];
 wait_for_flash_ready();
 }

NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren;
 __ISB();
 __DSB();
} 
 Best regards, 
 Laura

Edvin · Accepted Answer

Hello Laura, 
 That sounds plausible. When you are using the Zboss stack, you need to use it's flash management API, to make sure that they are not trying to use the flash at the same time, which can cause the other "user" to have an unsuccessful or incomplete flash operation, which in worst case can lead to corrupted zboss memory, and from there a lot of issues. 
 Please see the NVRAM documentation for the Zboss library: 
 https://infocenter.nordicsemi.com/topic/sdk_tz_v4.2.0/group__zboss__nvram.html?cp=9_3_5_1_9_10 
 You should use this to make the Zboss library aware that there are flash operations ongoing. 
 
 Best regards, 
 Edvin

Flash management with operative system

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