DP83TD510E: Unable to write to register 0x1834 bit 14

Hi Ivailo,

Register 0x1834 is an extended register and must be written to using the procedure given in section 6.3.10 of the datasheet (Note this register is in MMD1). Are you able to access extended registers other than 0x1834?

Thanks,

David

Hi David,

I'm using the dev board DP83TD510E-EVM and USB-2-MDIO tool where 'Extended Register' option is selected to 'Yes'.

PHY ID is zero and I successfully read the extended registers and I'm able to write to 0x8EE for example. But I'm unable to write to 0x1834 bit 14, 0x18F6 - bits 10 and 12, 0x18F8 - bits 13-15.

Maybe the tool has some bug?

I did the following test. Selected 'Extended Register" to 'No'

0x1F -> 0xD

0x1834 -> 0xF

0x401F -> 0xD

0 -> 0xE

1 -> 0xD

0x1834 -> 0xE

0x4001 -> 0xD

And read the register 0xE which returned 0x4002 instead of 2 - Can not write bit 14 to 0.

If now I select 'Extended Register' to 'Yes' and read 0x1834 it returns 0x251 - it seems that USB-2-MDIO tool doesn't read properly. Least significant nibble is 1 which is reserved value.

Best Regards

Ivailo

Hi David,

Thank you for your help! I believe that you unintentionally wrote 0834 instead of 1834 in register 0xE or I'm missing something (page 36 www.ti.com/.../dp83td510e)

The value that you write in register 0xD is '1' - the same for read and write. E.g. both scripts look the same with the only difference that at the end 0xE is written or read. Am I missing something or it is a mistake?

Here are the results:

1834_Read.txt file is open...
Register 000D is: 0001
Register 000E is: 0834
Register 000D is: 4001
Register 000E is: 4002
End of file.

1834_Write.txt file is open...
Register 000D is: 0001
Register 000E is: 0834
Register 000D is: 4001
Register 000E is: 0002
End of file.

1834_Read.txt file is open...
Register 000D is: 0001
Register 000E is: 0834
Register 000D is: 4001
Register 000E is: 0002
End of file.

I believe that this is the value of register 0x834.

Here are the scripts what I think they should look like (write 0 in 0xD for 'write access' - page 28, and 1834 in 0xE):

1834_Read_.txt:
begin
000D 0001
000E 1834
000D 4001
000E
end

1834_Write_.txt
begin
000D 0000
000E 1834
000D 4000
000E 0002
end

Results after I modified the scripts

1834_Read_.txt file is open...
Register 000D is: 0001
Register 000E is: 1834
Register 000D is: 4001
Register 000E is: 4002
End of file.

1834_Write_.txt file is open...
Register 000D is: 0000
Register 000E is: 1834
Register 000D is: 4000
Register 000E is: 0002
End of file.

1834_Read_.txt file is open...
Register 000D is: 0001
Register 000E is: 1834
Register 000D is: 4001
Register 000E is: 4002
End of file.

Do you have any thoughts?

Thank you very much for your time!

Best Regards!

Ivailo

Hi Ivailo,

See below note from a different datasheet (this note applies to all PHYs and should be present in DP83TD510E datasheet as well).

I see you are correctly able to read and write to register 0x1834 with the scripts I provided.

Thanks,

David

Hi David,

Thank you for your time checking on this!

Are you sure that the most significant nibble have that purpose in this chip?

There is an example on page 36 showing that it shouldn't be masked:

What about the read and write - you suggest to write value 1 on reg 0xD for both operations - am I missing something here?

Thank you!

Ivailo

Hi Ivailo,

The example on page 36 is an error and will be corrected in the next datasheet. This FAQ applies to all of our PHYs. As you can see with the shared scripts you are able to read the correct value of 0x4002 from register 0x1834, write the value of 0x0002, and read 0x0002 back again.

Thanks,

David

Hi David,

Thank you very much! It is all clear now. I hope I'll be able to help you so much some day.

Best Regards

Ivailo