We need to add a custom mac address in nrf52840. I check the offical way about wirting the address in URCR. BUT it can be reflash or erase by anyone. We want find a way to wirte our custom address only once and never be erase. So I try to write it in FICR by nrfjprog --memwr 0x10000114 --val 0x11223344 and it failed.
