LAN8740A Datasheet, PDF (83/136 Pages) Microchip Technology – Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology

LAN8740A/LAN8740Ai
To read or write an MMD register, the following procedure must be observed:
1. Write the MMD Access Control Register with 00b (address) for the MMD Function field and the desired MMD
device (3 for PCS, 7 for Auto-Negotiation) for the MMD Device Address (DEVAD) field.
2. Write the MMD Access Address/Data Register with the 16-bit address of the desired MMD register to read/write
within the previously selected MMD device (PCS or Auto-Negotiation).
3. Write the MMD Access Control Register with 01b (data) for the MMD Function field and choose the previously
selected MMD device (3 for PCS, 7 for Auto-Negotiation) for the MMD Device Address (DEVAD) field.
4. If reading, read the MMD Access Address/Data Register, which contains the selected MMD register contents. If
writing, write the MMD Access Address/Data Register with the register contents intended for the previously
selected MMD register.
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DS00001987A-page 83