S32K中的主题 Re: ETH MDIO driver

ETH MDIO driver

xingyun — Mon, 31 Aug 2026 07:17:21 GMT

We are using sia1110, and now we've noticed that when both TCP client and server are running simultaneously, one of them will randomly disconnect after some time. The client can reconnect successfully by clicking the reconnect button on the host machine, but the server cannot.

The same procedure does not have this problem on different platforms. Could you please explain to me the reason for this?

My current idea is to use MDIO to monitor the status between the MCU and the switch, but I'm currently facing some problems.

status_t Dwmac_LLD_Mii_Read_Reg(volatile DwmacReg *dwmac_reg, uint32_t phy_addr, uint32_t reg_addr, uint32_t *reg_data)

{

while (dwmac_reg->MAC_MDIO_ADDRESS.B.GB != 0U) {; }

dwmac_reg->MAC_MDIO_DATA.B.RA = reg_addr;

dwmac_reg->MAC_MDIO_DATA.B.GD = 0;

dwmac_reg->MAC_MDIO_ADDRESS.B.PA = phy_addr;

dwmac_reg->MAC_MDIO_ADDRESS.B.RDA = reg_addr;

dwmac_reg->MAC_MDIO_ADDRESS.B.GOC = 2U;

dwmac_reg->MAC_MDIO_ADDRESS.B.CR = 0xB;

dwmac_reg->MAC_MDIO_ADDRESS.B.GB = 1U;

while (dwmac_reg->MAC_MDIO_ADDRESS.B.GB != 0U) {; }

*reg_data = (uint16_t) (dwmac_reg->MAC_MDIO_DATA.R & 0x0000FFFFU);

return STATUS_SUCCESS;

}

Dwmac_LLD_Mii_Read_Reg(&ETHERNET_0, 0x1B, 0x2U, &reg_val);

The underlying function being used here, in which reg_val remains 0 all the time.

Re: ETH MDIO driver

PavelL — Mon, 31 Aug 2026 12:52:44 GMT

Hello @xingyun ,

Before analyzing the TCP disconnection and the MDIO read function, could you please provide some additional information about your setup?

Which exact SJA1110 device variant and silicon revision are you using?
Which MCU or processor is connected to the SJA1110 and which interface is used between them, for example RGMII, RMII, SGMII or another interface?
Could you provide a simplified connection diagram showing the MCU, SJA1110 ports and the devices running the TCP client and server?
Which TCP/IP stack and stack version are you using?
Which version of SJA1110 SDK/RTD is used in the project?
Does the TCP client and server run on the same MCU and the same Ethernet interface or on separate devices/interfaces?
Could you also clarify what exactly you intend to monitor using the MDIO read function? In particular, which device and register do PHY address 0x1B and register address 0x02 refer to in your setup? Please also share the relevant schematic section or connection details showing how the SMI interface, including the MDC and MDIO signals, is connected between the MCU and the SJA1110.

We kindly ask you to provide precise details for the questions above, as this will help us establish a clear understanding of your setup and avoid any potential misunderstandings at an early stage of the analysis.

Best regards,

Pavel

Re: ETH MDIO driver

xingyun — Tue, 01 Sep 2026 07:39:24 GMT

SJA110 2.0 and Using RMII

I want to use the MDIO to monitor the registers and check the status of the switch and MCU when one of the ports is disconnected. This is just one method of detection, as I'm not sure what causes the TCP server and client to fail to coexist simultaneously. Not sure which version it is.

xingyun_0-1788248086523.png

Re: ETH MDIO driver

PavelL — Wed, 02 Sep 2026 05:59:28 GMT

Hello @xingyun ,

To further help you I need more information. Please answer to all question below:

1. Which exact SJA1110 device variant do you use? SJA1110A, B, C or D?

2. What ports on SJA1110 are connected to TCPS and to TCPC?

3. Both used ports to TCPS and to TCPC used RMII?

4. TCPS and to TCPC are connected directly to RMII or is there any PHY between them?

5. How is SJA1110 configured? Is there any SW running on SJA1110 or SJA1110 acts only as a switch?

6. What software has been used to configure SJA1110? S32 Design Studio ?

Best regards,

Pavel