Nios® V/II Embedded Design Suite (EDS)
Support for Embedded Development Tools, Processors (SoCs and Nios® V/II processor), Embedded Development Suites (EDSs), Boot and Configuration, Operating Systems, C and C++
12627 Discussions

NIOS: MDIO: Platform Designer generates altera_eth_mdio.v that doesn't work


Hi Intel Community,

I have a strange error with MDIO interface on the NIOS II.
I'm using it to communicate with an external PHY.

I got an generated altera_eth_mdio.v file from a colleague where everything works fine.
My code can perfectly read and write any registers from the external PHY when I'm using his generated NIOS-HDL files.

When I generate new HDL files in the Platform Designer I get a different altera_eth_mdio.v file. All other files stay the same.
With this file I can't access any registers on the external PHY over the MDIO interface.

The .qsys file is the same in both designs.

Could you tell me why the Platform Designer generates a different altera_eth_mdio.v file?
Actually the configuration of the MDIO is very easy and I have absolutly no idea what is going wrong.

My workaround is to replace the altera_eth_mdio.v with the good one after generating HDL files.
But that's not a good solution

I appended my .qsys file and both generated altera_eth_mdio.v files.

Thanks a lot for your help.

Best regards,

0 Kudos
2 Replies

Ok, found it.

The TLK10232 we use in this project requires a longer MDIO preamble than the nios generates. So my colleague manually changed the file. And replaced it after generating new NIOS files. I didn't expect that...

We use Quartus Version18.1. Maybe in a newer Version this problem is fixed. If not it's maybe a good idea to make the preamble length configurable.

Have a nice day.

Best regards,




0 Kudos

There is a parameter for MDIO IP in Platform Designer as attached.

0 Kudos