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DP83822HF: cannot ping

Cherry Zhou
Mastermind 22235 points
Part Number: DP83822HF

Hi Team,

DP83822HF cannot be pinged using a PC (DP83822HF optical port, rewired to RJ45 connector via fiber optic transceiver, connected to computer side) .

Please see the following debugging steps:

1) 2 fiber transceivers are used to send and receive the transceiver, which is able to ping successfully and prove that the fiber transceiver is not a problem.

2) Use the internal loopback mode of the DP83822HF for transmit and receive. The oscilloscope test signals such as the Digital TX RX CLK of the MII are good and the transmit and receive interrupts are normal.

3) Using DP83822HF normal mode (non-loopback), ping the device on the computer side and finding that the ping is not possible. Through the test waveform it's found that TD_p/TD_m had a sine wave of 800 mV while the received rd_p/rd_m had only bias voltage but no waveform.

4) Reset signal of DP83822HF is normal and there is a reset action at power-up, MDIO communication is good. 

Please see the schematic below:

And the reading register is as follows:

00> DP83848_Init reg0x0:0x3100
00> DP83848_Init reg0x1:0x784D
00> DP83848_Init reg0x2:0x2000
00> DP83848_Init reg0x3:0xA240
00> DP83848_Init reg0x4:0xDE1
00> DP83848_Init reg0x5:0x0
00> DP83848_Init reg0x6:0x4
00> DP83848_Init reg0x7:0x2001
00> DP83848_Init reg0x8:0x0
00> DP83848_Init reg0x9:0x0
00> DP83848_Init reg0xA:0x4100
00> DP83848_Init reg0xB:0x1000
00> DP83848_Init reg0xC:0x0
00> DP83848_Init reg0xD:0x0
00> DP83848_Init reg0xE:0x0
00> DP83848_Init reg0xF:0x0
00> DP83848_Init reg0x10:0x2A05
00> DP83848_Init reg0x11:0x108
00> DP83848_Init reg0x12:0x8200
00> DP83848_Init reg0x13:0x0
00> DP83848_Init reg0x14:0xFF
00> DP83848_Init reg0x15:0x1653
00> DP83848_Init reg0x16:0x100
00> DP83848_Init reg0x17:0x49
00> DP83848_Init reg0x18:0x400
00> DP83848_Init reg0x19:0xA001

Could you please help check this case? Thanks.

Best Regards,

Cherry

  • TI__Genius 14006 points

    Hi Cherry,

    Just to clarify, is this for the DP83848 or the DP83822? You mentioned the 822 in your post but the dump is of the 848. Is the correct register dump attached?

    In your design, are the resistors and capacitors should be placed as close to the fiber transceiver as possible?

    Cherry Zhou said:
    3) Using DP83822HF normal mode (non-loopback), ping the device on the computer side and finding that the ping is not possible. Through the test waveform it's found that TD_p/TD_m had a sine wave of 800 mV while the received rd_p/rd_m had only bias voltage but no waveform.

    Would you be able to provide a picture of this?

    Best regards,

    Melissa