TMS320F28388D: Detecting ethernet link status on TMDSCNCD28388D

Daniel,

The link status/detection has to be done by the PHY layer. In the TMDSCNCD28388D Control card, there is an external PHY (DP83822) to the F28388D chip.  You will have to query that using the MDIO. Ethernet_readPHYRegister() API can be used to read the Basic Mode Status Register (BMSR) at address 0x0001 of the PHY.It contains a bit field Link Status which will tell whether the Link is up or not. 

Best Regards

Siddharth

Thank you very much.

I found this code in lwiplib.c

in hw_memmap.h : 

    #define EMAC_BASE 0x400C0000U

in f2838xif.h :

    #define EPHY_BMSR 0x00000001 // Ethernet PHY Basic Mode Status
    #define EPHY_BMSR_LINKSTAT 0x00000004 // Link Status

while LwIP was working well, 

I called "Ethernet_readPHYRegister(EMAC_BASE, EPHY_BMSR)" and printed out the return value.

It was always 0xFFFF, regardless of actual link status.

Can you guess Why?

Hi, 

Please refer this post 

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/550756/problems-reading-dp83822-register-0x0001-basic-mode-status-register

It mentions that the register 0x01 (BMSR) always requires two reads. This bit in the register is a LL (latch-low). Thus two reads are required to get the correct real-time status.

Best Regards

Siddharth