How to use the RGMII interface on the OM14510-SJA1105TJP EVB

[chlee77]

How to use the RGMII interface on the X1100 connector of the OM14510-SJA1105TJP EVB?

It seems that there is only RMII configuration for the extension board and LPC1788FET208 MCU.

Can I remove the resistors R904~R913 which means there would be no 50MHz RMII clock connected to LPC1788FET208 MCU? That's because I need to use the extension connector and I would like to set it as RGMII interface not RMII.

Best Regards

CH

[xiangjun_rong]

Hi, Jason,

The LPC1788FET208 just supports MII or RMII mode, it does not support RGMII mode, in other words, the Ethernet module of LPC1788 only supports 10M/100MHz mode, it can not support 1G mode. But it appears that the Ethernet port of SJA1105 supports RGMII mode. In other words, I think you can configure the Ethernet port of SJA1105 which is connected to LPC1788 as RMII mode, configure the other port as RGMII mode.

Hope it can help you

BR

Xiangjun Rong

[137579513]

Hi xiagjun,

    Could you please tell me how to connect to the x1100 extension? What type of connect header should I use?Thanks a lot!

Best Regards

-JJC

[chlee77]

Thank you so much, but my intention is to cut off all RMII lines which are connected to LPC1788FET208 and set this port as RGMII mode includes the 50MHz reference clock of RMII. So I could use RGMII mode on the extension connector because it seems that the extension connector and LPC1788 are shared the same port of SJA1105 after I checked the schematic, but I'm not sure about that.

Does the LPC1788 can still work if I cut off all RMII lines from SJA1105 on the SJA1105EVB? We have the other platform which is RGMII interface ONLY, and we want to connect our platform and the SJA1105EVB together. That's why we need to figure out all details before we buy the platform.

Best Regards

CH

[xiangjun_rong]

Hi, Jason,

If you cut off all RMII lines from SJA1105 on the SJA1105EVB, the LPC1788 can still work, it can still configure the Ethernet switch via SPI port.

BR

Xiangjun Rong