You, as the designer, determine your device's MAC address. You have options:

• Buy a support chip that your uC talks to in order to retrieve an unique MAC address that the support chip already has in ROM (for my low-quantity products, this is what I do).
• Get yourself a list of legitimate MAC addresses that you specify in your firmware (requires $money$). Google it.
• Tell everyone 'Good luck!' and make up your own addresses (note: If I recall correctly, there is a block of MACs that are designated to be lawlessly used, assuming the device remains only on your isolated subnet).

For the RA6M4 family, it appears that you set the MAC in the MAHR & MALR registers (RA6M4 Group User’s Manual: Hardware 26.2.15, 26.2.16).

(https://www.renesas.com/us/en/document/man/ra6m4-group-user-s-manual-hardware?language=en&r=1333976)

Good luck!

You, as the designer, determine your device's MAC address. You have options:

• Buy a support chip that your uC talks to in order to retrieve an unique MAC address that the support chip already has in ROM (for my low-quantity products, this is what I do).
• Get yourself a list of legitimate MAC addresses (requires $money$ Google it). Pick an address from that list, apply it to your device from your firmware. (Unique address, not to be used again).
• Tell everyone 'Good luck!' and make up your own address (note: If I recall correctly, there is a block of MACs that are designated to be lawlessly used, assuming the device remains only on your isolated subnet). See next item below.
• Make up a locally unique MAC, and set the "locally Administered Addresses" (LAA) bit in the MAC address. (See Wikipedia "MAC Address" : "Universal vs. local (U/L bit)". " ...setting (assigning the value of 1 to) the second-least-significant bit of the first octet of the address." I'm not familiar with this method or the ramifications on your LAN.

For the RA6M4 family, it appears that you set the MAC in the MAHR & MALR registers (RA6M4 Group User’s Manual: Hardware 26.2.15, 26.2.16).

(https://www.renesas.com/us/en/document/man/ra6m4-group-user-s-manual-hardware?language=en&r=1333976)

Good luck!

You, as the designer, determine your device's MAC address. You have options:

• Buy a support chip that your uC talks to in order to retrieve an unique MAC address that the support chip already has in ROM (for my low-quantity products, this is what I do).
• Get yourself a list of legitimate MAC addresses that you specify in your firmware (requires $money$). Google it.
• Tell everyone 'Good luck!' and make up your own addresses (note: If I recall correctly, there is a block of MACs that are designated to be lawlessly used, assuming the device remains only on your isolated subnet).

For the RA6M4 family, it appears that you set the MAC in the MAHR & MALR registers.

Good luck!

You, as the designer, determine your device's MAC address. You have options:

• Buy a support chip that your uC talks to in order to retrieve an unique MAC address that the support chip already has in ROM (for my low-quantity products, this is what I do).
• Get yourself a list of legitimate MAC addresses that you specify in your firmware (requires $money$). Google it.
• Tell everyone 'Good luck!' and make up your own addresses (note: If I recall correctly, there is a block of MACs that are designated to be lawlessly used, assuming the device remains only on your isolated subnet).

For the RA6M4 family, it appears that you set the MAC in the MAHR & MALR registers (RA6M4 Group User’s Manual: Hardware 26.2.15, 26.2.16).

(https://www.renesas.com/us/en/document/man/ra6m4-group-user-s-manual-hardware?language=en&r=1333976)

Good luck!