Well, localtalk is LLAP. Its defined in that standard how it talks on the port.
So all an ethernet adapter is, is an LLAP to Ethernet translator.
So what you need to do is lookup LLAP and find out how it is framed, etc... and use the arduino to decode it. Phone-Net appears to convert the RS422 full duplex bus into a single RS-485 half-duplex bus system.
So all you need is to setup the localtalk bus as half-duplex with only D+ and D- lines. Then hook these into a regular MAX488 or an ADM483 transceiver, to the AVR.
That will establish something that can listen/talk on the bus. BUT you need to come up with a way to decode the databits on the bus, which is all in the LLAP standard.
So all an ethernet adapter is, is an LLAP to Ethernet translator.
So what you need to do is lookup LLAP and find out how it is framed, etc... and use the arduino to decode it. Phone-Net appears to convert the RS422 full duplex bus into a single RS-485 half-duplex bus system.
So all you need is to setup the localtalk bus as half-duplex with only D+ and D- lines. Then hook these into a regular MAX488 or an ADM483 transceiver, to the AVR.
That will establish something that can listen/talk on the bus. BUT you need to come up with a way to decode the databits on the bus, which is all in the LLAP standard.