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DP83822IRHBR

qiang xiang
Intellectual 290 points

Dears, 

    May I ask two questions about   DP83822IRHBR? Thank you .

My customer uses this config as belows (the red rectangle):

My question is :

1/   If I don't insert the internet cable ,  can I get the FLP signal ?  Actually , I can't  get  the FLP signal in Oscilloscope.

      I'm not sure if the DP83822 will always generate the FLP signal in this config mode.

2/    We set  the Auto-Negotiation  enabled  by regsiter configuration, using bit[12] in the Basic Mode Control Register (BMCR, address 0x0000).

      When inserted  the internet cable, DP83822 maybe works in 10base, mybe works in 100base. What is the major factor to determine  DP83822 work speed?  10base or 100base?

Thank you very much.

  • 0
    TI__Mastermind 19780 points
    Hi qiang xiang,

    1. If you don't insert the cable, you will be able to measure the output of the DP83822, and you will see FLP coming from the DP83822. In the mode you selected, the FLP will transition from TD+/- to RD+/- and back again quickly. This is because auto mdix is enabled. This is a good setting. You should see FLP coming out of the DP83822!

    2. If auto-negotiation is set, using register 0x0 bit[12], and all speeds are advertised, as set in register 0x4, then the speed the DP83822 works at once the cable is connected is based on the speed on the other end. If the PHY on the other end connected to DP83822 is only capable of 10M, then DP83822 will work at 10M. If the PHY on the other end can do 10M and 100M, and is in auto-negotiation also, then DP83822 will select 100M mode.

    Best Regards,