The EUI64 is composed of 8 bytes (https://standards.ieee.org/develop/regauth/tut/eui64.pdf), for the CGE reference design, the values of first three bytes is fixed for Cisco's boards, byte0=0x00, byte1=0x17, byte2=0x3B. Vendor should use their own OUI value. The rest five bytes is either configured by cfgwriter (please see detail of cfgwriter READ ME) or read from MCU’s 96-bit unique device identifier. The 96-bit unique device identifier of Contex-M3 is located at base address 0x1FFF7A10, its last 40 bits(bit39:0) are selected as the last five bytes of EUI64, byte3 = bit39:32, byte4 = bit31:24, byte5 = bit23:16, byte6 = bit15:8, byte7 = bit7:0 (showed as pic at last).
For example, if one of the endpoint’s 96-bit unique device identifier is 0x333631363032470800410037 (bit95~0), the EUI64 of the endpoint would be 00173B0800410037.