DP83849I: About setting odd address by PHY address register

Hello Vibhu,

Thank you for reply.

I have more some question.

(1) According to datasheet(page77), default value of PHY address register[4:0] is described as following.

After reset, the PHY address register(PHYADDR) [4:1] is latched by bootstrap input pins.

And after that, can we write to new value to this register(PHYADDR) [4:1] as PHY address again?

(2) According to datasheet(page10), the PHY address bit[0] depends on the Port A/B

and bit[4:1] are selected based on bootstrap input pins.

After reset, bit[4:1] are latched by bootstrap input pins.

In this case, how is value in PHY address register(PHYADDR) bit[0]? (0 or 1?)

And can we write to new value(0or1) to PHY address register(PHYADDR) bit[0]?

Or is bit[0] fixed to 0?

Regards,

Tao_2199

Hello Vibhu,

Thank you for reply.

We have understood by your description.

This time , we were confused by datasheet typo. (page 62,77)

Do you have a plan about new revision? (Modify typo.)

I hope that these typos will be modified soon.

Regards,

Tao_2199

Hello Tao,

Thanks for pointing this out, I will make note of this. I'm glad the issue is clear.

Thanks,

Vibhu

Hello Vibhu,

Many thanks!
I will close this thred.

Regards,

Tao_2199

Hi Vibhu,

I work with Tao_2199 and we have same project.

My customer tried following steps.

It seems that Read and Write access of PHTCR(0x19) and individual setting for A/B of PHY Address are possible.

It is not described on datasheet.  Is it possible to apply this way?

■The procedure for changing the PHY address

When the hardware is up, PHY ADDR = 0 for port A and PHY ADDR = 1 for port B.

① Write 3 to PHYCR (19h) for PHY ADDR = 0 of port A and change to PHY ADDR = 3.

② Write 0 to PHYCR (19h) for PHY ADDR = 1 of port B and change to PHY ADDR = 0.

③ Write 1 to PHYCR (19h) for PHY ADDR = 3 of port A that was changed by previous step, and change it to PHY ADDR = 1.

④ The address of A port and B port was able to be exchanged.

　 Rewrite including PHY ADDR [0] was possible.

Best Regards,

ttd

Hi Vibhu,

Thank you for your reply.

Sorry to bother you again.

①

I guess that writing to PHYADDR had not been tested  for the correct operation(specification) during developing DP83849 at the time..

So is writing function prohibited ?

②

Not only DP83849, but also DP83822 is RO(read only) and DP83825 is H(hardware strap) for PHY ADDR.

Is there any background(issue) to profibit writing to the PHY ADDR through software after strap configuration(HW)? 

If you have some reason, I hope that datasheet of DP83849I/C will be fix from "RW" to "RO" or "H" in the near future.

Best Regards,

ttd