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SN75DP130 / about Table.3 Main Link EQ Configurations

Sho Ogane
Genius 5575 points
Other Parts Discussed in Thread: SN75DP130

Hi all.

This device has 3 frequency pattern RBR(1.62Gbps), HBR(2.7Gbps) and HBR2(5.4Gbps).
And HBR and HBR2 have 8 EQ gain.
・HBR
0dB, 1.5dB, 3dB, 4dB, 5dB, 6dB, 7dB, 9dB
・HBR2
0dB, 3.5dB, 6dB, 8dB, 10dB, 13dB, 15dB,18dB

Please check "LINK TRAINING AEQ(Lx) LANE 0 to 2" of Table 3
AEQ(Lx)=xdB at 2.7GHz.

HBR(2.7GHz) is not supported 3.5dB and 8dB, 10dB, 13dB, 15dB, so I think HBR2(5.4GHz) is correct in Table 3.
Is  my understanding right?

Best Regards,
Sho Ogne

  • 0
    TI__Mastermind 23815 points
    Hi Sho,

    2.7GHz comes from 5.4Gbps, this is because of the 1,0 toggling the signal may has.
    For the case you are talking about, it is when link training is disabled, so EQ is fixed at 2.7GHz(for 5.4Gbps).
    If you enable link training, DP130 will adjust EQ in a range selected by pre-emphasis level. For exmaple, if pre-emphasis level is L0, then EQ will be selected in the range from 0dB to 8dB at 2.7GHz.
    The values you talk about in tables 11 to 18, are to set a fixed EQ value depending on Lane numer and pre-emphasis level, but you have to enable EQ settings controlled by I²C register settings(reg 05h bit 7).

    Regards
  • 0 in reply to Moises Garcia
    Genius 5575 points

    Hi Moises san

    Thank you for your reply.
    I understood your comment, I overlooked the unit of GHz or Gbps.

    Best Regards,
    Sho Ogane

  • 0 in reply to Sho Ogane
    Genius 5575 points

    Hi Moises san

    I have 3 questions, about SN75DP130.

    【Q1】
    My customer sets the following resister, my customer would like to check default output(pre-emphasis and EQ re 0dB).
    However the expected value is not output, so please check the registers.

     Address = 0x01
       data    = 0x01
       ↓
     Address = 0x03        Main Link squelch sensitivity
       data    = 0x08        squelch detection disabled,  40mVpp set
       ↓
    Address = 0x05        EQ settings controlled by I2C register settings
      data     = 0x80        0 dB EQ gain (default)
       ↓
    Address = 0x06
      data     = 0x00        0 dB EQ gain (default)
       ↓
    Address = 0x07
      data     = 0x00        0 dB EQ gain (default)
       ↓
    Address = 0x08
      data     = 0x00        0 dB EQ gain (default)
         ↓
    Address = 0x09
      data     = 0x00        0 dB EQ gain (default)
       ↓
    Address = 0x0A
      data     = 0x00        0 dB EQ gain (default)
       ↓
    Address = 0x0B
      data     = 0x00        0 dB EQ gain (default)
       ↓
    Address = 0x0C
      data     = 0x00        0 dB EQ gain (default)

    ※other address are default

    【Q2】
    Please check Table.9. Offset = 03h.
    My customer doesn't know recommend squelch detection threshold set value, and ask us how to set recommend value.
    Please tell me how to decide recommend value.

    【Q3】
    This device(all default set) couldn't pass the following contents at compliance test.
    5.3.1.2           Successful link training with request of higher differential voltage swing during clock recovery sequence
    5.3.1.5           Successful link training at lower link rate due to loss of symbol lock during channel equalization sequence
    5.3.2.2           IRQ_HPD pulse due to loss of inter-lane alignment lock
    5.4.1.3           Main stream data unpacking and unstuffing - most packed TU
    5.4.2              Main video stream format change handling

    However the following setting device passed compliance test.
    Please give me your advise to improve result.(e.g. Change     squelch detection threshold set to 40mVpp)

    0x01     01h   1 – Shutdown mode is determined by EN input, normal operation
    0x03     18h   01 – Main Link IN0p/n squelch detection threshold set to 80mVpp (default)
                            1 – Main Link IN0p/n squelch detection disabled"
    0x05     D2h   1 – EQ settings controlled by     I2C register settings
                101 – 6 dB (HBR); 13 dB (HBR2) 
                010 – 3 dB (HBR); 6 dB (HBR2)  "
    0x06     10h   001 – 1.5 dB (HBR); 3.5 dB (HBR2)
                000 – 0 dB EQ gain (default)  "
    0x07     52h   101 – 6 dB (HBR); 13 dB (HBR2) 
                010 – 3 dB (HBR); 6 dB (HBR2)  "
    0x08     10h   001 – 1.5 dB (HBR); 3.5 dB (HBR2)
                000 – 0 dB EQ gain (default)  "
    0x09     52h   101 – 6 dB (HBR); 13 dB (HBR2) 
                010 – 3 dB (HBR); 6 dB (HBR2)  "
    0x0A    10h   001 – 1.5 dB (HBR); 3.5 dB (HBR2)
                000 – 0 dB EQ gain (default)  "
    0x0B    52h   101 – 6 dB (HBR); 13 dB (HBR2) 
                010 – 3 dB (HBR); 6 dB (HBR2)  "
    0x0C    10h   001 – 1.5 dB (HBR); 3.5 dB (HBR2)
                000 – 0 dB EQ gain (default)  "
    0x00    00h

    ※other address are default

    Sorry, I ask many question, please give me answer as soon as possible.

    Best Regards,
    Sho Ogane
  • 0 in reply to Sho Ogane
    TI__Mastermind 23815 points
    Hi Sho-san,

    [Q1]
    SN75DP130 is a redriver not an equalizer , so the output swing won't depend on EQ values, it will depend on Output swing configuration.

    [Q2]
    This depends on the noise floor, if there is a lot of noise you would need to set a higher threshold so noise doesn't wake up the device.

    [Q3]
    Have you tried only disabling squelch leaving all other parameter as default?
    Do you have any traces you can share with us?

    Regards
  • 0 in reply to Moises Garcia
    Genius 5575 points

    Hi Moises san

    Thank you for quick reply.
    I teach your comment.

    I have any questions about Q1 and Q3.

    【Q1】
    Is my customer's setting that I told last my response 0dB pre-emphasis?
    Can I change pre-emphasis by setting "TRAINING_LANE0_SET" address?

    【Q3】
    About your comment " Have you tried only disabling squelch leaving all other parameter as default?", I have one more question.
    Could you tell me how to set disabling squelch?

    Best Regards,
    Sho Ogane

  • 0 in reply to Sho Ogane
    TI__Mastermind 23815 points
    HI Sho-san,

    [Q1]
    Yes, you may write DPCD registers to configure pre=emphasis and VOD, I'll send you by email our application note for eDP, there you can see how to write these registers.

    [Q3]
    You disable squelch by setting to 1 bit 3 from register 03h, you have done it in your previous configuration, if you disable squelch it doesn't matter what squelch sensitivity level yu set.
    Address = 0x03 Main Link squelch sensitivity
    data = 0x08 squelch detection disabled, 40mVpp set

    Regards
  • 0 in reply to Moises Garcia
    Genius 5575 points

    Hi Moises san

    Thank you for the reply.
    I have two questions.

    【Q1】　About Voltage swing level value.

    My customer set Voltage swing level 800mV. 

    Voltage Swing Level2 （800mVpp)、Pre-Emphasis 0dB →measured result : 800mVpp
    Voltage Swing Level2 （800mVpp)、Pre-Emphasis 3.5dB →measured result : 750mVpp

    This phenomenon is not good.Is this phenomenon normal operation?
    Please give me improvement plan.

    【Q2】　About the compliance test of pre-emphasis

    My customer is doing compliance test.

    My customer set Pre-Emphasis value 0dB →3.5dB
    The pass value of measured result is 2dB, however measured result is 1.8dB.
    So my customer failed this test.

    Please give me your comment.

    Best Regards,
    Sho Ogane