DP83867IS: How to specify the speed at which PHYs link.

Hello,

Thank you for your query. Currently, US offices are closed for Labor Day holiday. Please expect a response during the middle of the week.

Sincerely,
Gerome

Hello,

Which speed are you looking to fix at? It is generally recommended to have auto-negotiation on in all situations.

Sincerely,

Gerome

Hi,

thank you for your reply.

My customer wants to fix to 10BASE or 100BASE.
When I specify the speed in "SPEED SELECTION LSB" and "SPEED SELECTION MSB", only 10BASE is linked up.
100/1000Base is not linked up.
Why can only 10BASE be linked up?

Could you tell me how to fix to 10BASE or 100BASE?

BR.
Kengo.

Hi Kengo,

I will look to recreate in lab.

Sincerely,

Gerome

Hi Gerome,

Thank you so much for checking the EVM and report.

I understood that it can be used at a fixed speed.
However, our setting is the same as your result.

Could you tell me some questions?

1 : Please let me know the trap setting.
2 : When I want to communicate at 100mbps, I write Reg 0x0 = 0x2100,
     What logic should be used for "TXCLK", "RXCLK", "TX_CTRL", "RX_CTRL", "TX_D0-D3" and "RX_D0-D3" in PHY during and after writing?

BR.
Kengo.

Hi Gerome,

Thank you for your support.

For unlinked devices, TX_CLK, TX_CTRL and TX_D[3:0]  were OPEN.
Auto-negotiation was able to link up with this setting.
If the speed is fixed, is there any communication on  TX_CLK, TX_CTRL and TX_D[3:0] ?

BR.
Kengo.

Hi Gerome,

Thank you for your reply.

Is it possible to communicate by fixing the logic of the TX_pin?
If so, what should I set the logic?

And, could you explain why auto-negotiation and fixed speed cannot be connected?

BR.
Kengo.

Hi Kengo,

I don't understand what you mean by "fixing the logic" of the TX_ pins. Is it possible to reword? These pin states are set by the MAC interface standard.

For auto-negotiation, the PHY will be sending out and expecting link pulses on the line. When fixed speed is set, the PHY will be beginning to send out signals that are not link pulses. Thus, there is a mismatch in expected signaling for linkup.

Sincerely,
Gerome

Hi Gerome,

Thank you for your quick reply.
It's very helpful for me.

Sorry for the lack my information.

Due to the circuit, I'd like to fix the TX_pins to Low or High.
If fixed logic is difficult, please let me know.

BR.
Kengo.

Hi Gerome,

Does this mean that txpin needs to be allowed to communicate?
In other words, PHY does not work with fixed logic?

BR.
Kengo.