DP83867IR: Access to extended register fails

Atsushi Takahashi

Part Number: DP83867IR

Tool/software:

Hi Team,

The customer tried "Improving Link-up Margins for Short Cables" in the DP83867 Troubleshooting Guide below.
www.ti.com/.../snla246c.pdf

Most of the registers listed here are extended registers, but even when accessing them according to the FAQ below, writing fails.
[FAQ] Extended Register Space Access for Ethernet PHYs
e2e.ti.com/.../faq-extended-register-space-access-for-ethernet-phys

Specifically:
- Writing 5555 to Register 0x0115, whose default value is B8BB, the read value will be DDDD.
- Writing 0771 to Register 0x0118, whose default value is 8BF9, the read value will be 8FF9.

What could be the cause?
Please let me know if you have any advice on how to write correctly.

Best Regards,

4 months ago

0 David (ASIC) Liu 4 months ago

TI__Guru**** 176281 points

Hi,

Are they following the below extended register write?

Thanks

David

0 Atsushi Takahashi 4 months ago in reply to David (ASIC) Liu

Expert 1405 points

Hi David-san,

Thank you for your reply.

Are they following the below extended register write?

Yes, I think the contents of the data sheet and FAQ are the same.

They tried writing it this way but it didn't work.

0 David (ASIC) Liu 4 months ago in reply to Atsushi Takahashi

TI__Guru**** 176281 points

Hi,

Are they able to successfully write and then read the standard register 0x00 to 0x1F?

Thanks

David

0 Atsushi Takahashi 4 months ago in reply to David (ASIC) Liu

Expert 1405 points

Hi David-san,

Yes, they successfully access standard registers 0x0000 to 0x001F, and extended registers except 0x0115 and 0x0118.

0 David (ASIC) Liu 4 months ago in reply to Atsushi Takahashi

TI__Guru**** 176281 points

Hi,

Please see this e2e thread, https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1441972/dp83867ir-to-resolve-link-up-issue-for-a-short-cable, so the extended register access is working as expected.

Thanks

David

0 Atsushi Takahashi 4 months ago in reply to David (ASIC) Liu

Expert 1405 points

Hi David-san,

Thank you for your reply,

I understand 0x0115.

What about 0x0118?

Is there a read-only bit at 0x0118?

0 J 4 months ago in reply to Atsushi Takahashi

TI__Genius 11786 points

Hi Takahashi-san,

David-san is on travel so his response may be delayed.
But, yes there are read-only bits on 0x0118, the same bits described in the E2E post that David replied.

Best,
J

0 David (ASIC) Liu 2 months ago in reply to J

TI__Guru**** 176281 points

Hi,

I will go ahead and close this thread since there is no response. You can either respond to this thread to re-open it or create a new thread if you need continue support.

Thanks

David

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DP83867IR: Access to extended register fails