Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Highlighted
Beginner
52 Views

TSE MAC phy MDIO write not working.

I am able to read register 0 of my phy by initiating a read command to address xA0 in the Avalon bus. the result is x1140. However if I try to write to this same address, no MDIO transaction takes place and the waitrequest remains high indefinitely. a reset of the MAC avalon port is required to regain access. Am I missing a step to get the write transaction to complete?

0 Kudos
4 Replies
Highlighted
Moderator
29 Views

Re: TSE MAC phy MDIO write not working.

Hi,

 

I noticed you are accessing mdio space 1 address 0xA0 instead of address 0x080 is due to you are using the address space for PCS function already ?

 

Some of the factor that I think maybe affecting your mdio write access is like below

  1. TSE IP MDIO host clock divisor setting - ensure MDC clock frequency does not exceed 2.5MHz
  2. External PHY Initialization using MDIO address -> TSE MAC Base Configuration Reg 
  • 0x0f for mdio_addr0
    • 0x10 for mdio_addr1
    • have you initialize and configure mdio_addr1 to correct PHY chip address before you perform wrire/read access ?
  1. Did you connect MIDO output enable connection for "mdio_oen" port, correctly ?

 

Thanks.

 

Regards,

dlim  

0 Kudos
Highlighted
Beginner
29 Views

Re: TSE MAC phy MDIO write not working.

Hi Dlim,

 

My core instantiation includes the PCS. My understanding is address space 0 is unavailable when using the PCS function.

  • My Avalon clk is 100 mhz, and the divider is set to 80, so i should have an MDC of 1.25MHz
  • I write x"0F" to addresss x"10" before initiating a read or write to address x"A0". My phy address is "1111"
  • Again, I am able to read data from the phy, but a write locks up the avalon interface with waitrequest held high and no transaction initiated on the MDIO bus
  • I have MDIO connected as below :

MDIO  <= mdio_out when mdio_oen = '0' else 'Z';

  •  
0 Kudos
Highlighted
Moderator
29 Views

Re: TSE MAC phy MDIO write not working.

Hi,

 

Yup, address space 0 will be occupied when PCS function is in used as explained by the TSE user guide doc.

 

Your MDIO setup looks correct.

 

I presume you have supply <= 125Mhz clock correctly to MAC control register clk pin as well. (which is the avalon bus clock)

 

My other debug suggestion for you is

  • Have you tried to run TSE simulation before to ensure your whole Quartus design is connected and working correctly. Then you can cross check your MDIO in sim waveform as well. This is to ensure nothing wrong with your Quartus design
  • Have you tried to access other reg address of your external PHY chip besides 0xA0 ?
  • Lastly, you can also use Oscilloscope to probe your on board external PHY chip MDIO bus when you try to perform a write transaction.
    • If no signal toggling on board then you know FPGA TSE IP doesn't send out the MDIO write transaction
    • Else if you saw signal toggling on board then maybe there is an issue with your external PHY chip

 

Thanks.

 

Regards,

dlim

0 Kudos
Highlighted
Moderator
27 Views

Re:TSE MAC phy MDIO write not working.

HI,


I have not hear back from you for close to 1 month.


Hopefully you are making progress on the debug.


For now, I am setting this case to closure. Feel free to post new forum thread in future if you still have enquiry in future.


Thanks.


Regards,

dlim


0 Kudos