is the internet configuration on otto will be the same as it was for DUE, that the chip has ethernet bus but will nerver be enable.. ?
Good question. I'm curious too. I looked at the ST datasheet and the Star Otto schematic briefly.
Not sure if this is 100% correct, but here's what I see so far...
Signal Possible Pins & Net Names
------ -------------------------
RXD0 PC4=AD9=Analog9
RXD1 PC5=AD3=Analog3
RXDV PA7=AD7=Analog7
RXER (looks like ST does not use this RMII signal?)
TX0 PB12=CAN2_TX=Digital54 PG13=USART6_CTS=Digital53
TX1 PB13=CAN2_RX=Digital52 PG14=USART6_TX=Digital51
TXEN PB11=USART3_RX=Digital19 PG11=PIN24=Digital24
CLK ?????? (I can't tell which pin the chip uses)
The important RMII signals all appear to go to shield-accessible pins.
But it's not clear to me which pin this chip uses for the 50 MHz RMII clock. A quick search turned up
this conversation which talks of using PA1 for the clock. That is connected to digital pin 1, so at least it's available, but using the same pin as the very commonly used Serial pin would be a little unfortunate.
I couldn't find any mention of RXER. Looks like ST might not use this RMII signal at all. Maybe they just let in corrupted data and depend on the ethernet frame crc checks or TCP packet checksums reject it?
I didn't trace out where the MII signal go, with the assumption a shield would opt for fewer 50 Mbit/sec signals rather than more 25 Mbit/sec signals.
Also didn't bother looking for the MDIO signals. The Arduino Ethernet library doesn't offer any APIs for PHY management (eg, is a cable actually attached, what speed is it using, etc) so it seems unlikely they'll get used.