Hi,
I have a board where a PHY is connected to a SJA1105Q switch via RMII. Other than descripbed in the switch reference manual, the 50MHz reference clock is generated by the PHY and supplied to the switch port's REF_CLK pin.
Is it possible to configure the REF_CLK pin to be an input when the switch port is in MAC mode?
Regards
Georg
No, it is not possible. In MAC mode RMII port of the switch outputs REF_CLK only. You can either, change configuration of the PHY to use external REF_CLK (from the switch), or set the switch's port to RMII PHY mode.
Regards,
Bulat
Hi,NXP experts,
There is a description in datasheet page15 like below.From my understanding the REF_CLK can be used as an output even acts as RMII MAC mode.
Can you please explain more?Thank you.
"RMII data is exchanged via 2-bit data signals TXD[1:0] and RXD[1:0] as shown in
Figure 7. Transmit and receive signals are synchronized with the shared reference clock,
REF_CLK.
In both the PHY-MAC (i.e. PHY to switch) and MAC-MAC (i.e. processor to switch)
configurations, the REF_CLK output on the Ethernet switch can provide the shared
reference clock."
BR
Yang