LAN8742A read io is always 0xFFFF. [STM32H747I-DISCO]

[sjeon.11]

Hello Sir.

In STM32H747I-DISCO board​, LAN8742A IC cannot read properly.

Always read only the 0xFFFF value.

In the same source, NUCLEO-H745ZI-Q board reads IO of LAN8742A well.

In LAN8742.c 

&regvalue is always 0xFFFF.

 if((pObj->IO.GetTick() - tickstart) <= LAN8742_SW_RESET_TO)

            {

              if(pObj->IO.ReadReg(pObj->DevAddr, LAN8742_BCR, &regvalue) < 0)

              {

                status = LAN8742_STATUS_READ_ERROR;

                break;

              }

            }

            else

            {

              status = LAN8742_STATUS_RESET_TIMEOUT;

 break;

            }

Anyone please help.

[TOlli]

I had similar issue on a custom board. The problem was that I had wrong configuration of pins in the LAN8742A. Check any jumpers so that the chip is put into correct mode, you probably want RMII mode.