DP83848I: How to switch speed mode without power cycle

Atsushi Takahashi

Expert 1040 points

Part Number: DP83848I

Tool/software:

Hi Team,

The customer would like to switch the mode from fixed 100Base-T to fixed 10Base-T without power cycle.

They changed the register settings with the following procedure, but it didn't switch.

Could you tell me the correct procedure?

1) At power up, set Bit13=1, Bit8=1 in the BMCR (Basic Mode Control Register); 100Mb/s, Full duplex

2) Set Bit15=1 in the BMCR; Reset

3) Set Bit13=0, Bit12=0, Bit9=0 in the BMCR, and set Bit8=1; Auto-Negotiation Disabled, 10Mb/s, Full duplex

Best Regards,

2 months ago

0 Gerome Cacho 2 months ago

TI__Mastermind 32515 points

Hello,

Do you require forcing the speed/duplex, or could this be solved by modifying the advertisements (Reg 0x4)?

Sincerely,

Gerome

0 Atsushi Takahashi 1 month ago in reply to Gerome Cacho

Expert 1040 points

Hi Gerome-san,

Thank you for your reply.

I require forcing the speed/duplex not advertisements for Auto-negotiation.

0 Gerome Cacho 1 month ago in reply to Atsushi Takahashi

TI__Mastermind 32515 points

Hi Takahashi-san,

Thank you for your reply. How are you determining that the speed is the same? What is register 0x10 reading before and after you change speeds? I would expect MLT3 signaling if auto-neg is disabled and speed is set to 100Mbps, while in 10Mbps, the line might be either silent or showing Manchester signals.

Sincerely,

Gerome

0 Atsushi Takahashi 1 month ago in reply to Gerome Cacho

Expert 1040 points

Hi Gerome-san,

They determine that the speed is same by the link light of HUB.

I'll check the register 0x10 reading.

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DP83848I: How to switch speed mode without power cycle