[FAQ] DP83TG720S-Q1: How to read or write registers in extended register space of Ethernet PHY?

write procedure for MMD "1F" registers:

write reg<000D> = 0x001F

write reg<000E> = <address>

write reg<000D> = 0x401F

write reg<000E> = <value>

read procedure for MMD "1F" registers:

write reg<000D> = 0x001F

write reg<000E> = <address>

write reg<000D> = 0x401F

read reg<000E>

Note : To read/write MMD "1" registers, replace 1F with 01.

Note : Above write and read procedure is normally used for registers with address greater than 0x001F. But it can also be used for any address in general.