MIMX8SL1AVNFZBA Eth to SJA1110A configuration

[nxp82977]

Hi we are in the middle of bringu=ing up an iMX8dl based design. the eth0 is routed to an NXP eth switch.

but we only see a 25MHz clock expecting a 50mHz.

attached the schematic section for the imx and the switch.

Question: please confirm if the connectiones between imx and SJA1110 are done properly for RGMII interface or MII interface.

Also please confirm what speeds are supported as the DS only talks about 100Mbps (RGMII) or 100Mbps (RMII) but the RM menatioans all :

14.5.2.2 Using PHY interfaces
This module support the following modes:
• RMII 10/100 Mbps interface
• MII 10/100 Mbps interface
• RGMII 10/100/1000 Mbps interface

Br Martijn

[juanpablo_monterocastro]

Hi @nxp82977 

I'm currently looking at this, I apologize I forgot to update the ticket. I'll let you know when I have an update.

[nxp82977]

Hello Richard,

thank for the response and that cnd of matches our suspission.

I have added the dtb, could you have a look at this and let me know what is wrong? then i can fwd that to my sw team. (Im the HW guy )

thx Martijn

[seb_haezebrouck]

Hi Martijn,

Do you have the datasheet of the Ethernet transceiver used ?

Best regards,

Seb

[nxp82977]

Hi Seb. its the NXP SJA1110A. see attached.

We did find something in the meantime. seem like the imx should be configured for MII Reversed mode. is that possible? as it will be MAC to MAC see figure 13 and figure 15

[richard_stulens]

Hi Martijn,

When you see a 25 MHz clock, it may be an indication that the controller is configured for MII interface (4-bit data). When it is configured for RMII (2-bit data) the clock is expected to be 50 MHz.

Although the Ethernet controller supports MII interface mode, it should not be used as not all signals are available on pins. Hence RMII or RGMII (gigabit) mode should be used to connect to the switch.

I do not have the SJA1110 data sheet at this time, so I do not know if RMII/RGMII modes can be used.

Can you add it to this thread so we can check the connections?

Regards,

Richard