TMDS181 Question

Mehrdad Bradaran

Intellectual 430 points

Other Parts Discussed in Thread: TMDS181

Hello,

On the TMDS181 I need to:

1) Swap receive lanes.

2) Swap the polarity of each lane.

The pin function description in section 5 for SWAP/POL (pin-1) is as follows (please see attached):

SWAP/POL = H: receive lanes polarity swap (retime mode only)

SWAP/POL = L: receive lanes swap (redriver and retime mode)

SWAP/POL = No connect: normal operation

Based on the description, the SWAP/POL pin can only enable lane swapping or polarity swapping, but not both at the same time. Can you please confirm if that is the case?

Can I enable both without using the I2C interface?

The note in the descriptions for LANE_SWAP and LANE_POLARITY bits in the control register (09h) seem to indicate that both are enabled when SWAP/POL pin is High.

Please confirm.

Thanks,

Mehrdad.

over 7 years ago

0 Elias Villegas M. over 7 years ago

TI__Guru* 76130 points

Hello,
Sorry for the delay,
A support engineer has been assigned and will reply soon.
regards

0 Moises Garcia over 7 years ago

TI__Mastermind 23815 points

Hi Mehrdad,

In GPIO mode there is no way you can set both lane and polarity swap.

Bbesides polarity swap only works in retimer mode, you would need to configure it in retimer mode across full data range in register 0x0A[1:0]

Regards

0 Mehrdad Bradaran over 7 years ago in reply to Moises Garcia

Intellectual 430 points

Hello Moises,

Can you please confirm that my connections are correct if lane and polarity swap are enabled. I will email you the schematic.

Thanks,

0 Moises Garcia over 7 years ago in reply to Mehrdad Bradaran

TI__Mastermind 23815 points

Hi Mehrdad,

Lane swap and polarity swap can be implemented at the same time in retimer mode, polarity swap doesn't work in redriver mode.

You will need to set retimer mode across full range 250MBps to 6Gbps

Saludos

0 Mehrdad Bradaran over 7 years ago in reply to Moises Garcia

Intellectual 430 points

Hi Moises,

How did their schematic look? Any suggestions?

Thanks,

0 Moises Garcia over 7 years ago in reply to Mehrdad Bradaran

TI__Mastermind 23815 points

Hi Mehrdad,

Please share full schematic in order to conduct a proper review.

Regards

0 Mehrdad Bradaran over 7 years ago in reply to Moises Garcia

Intellectual 430 points

I sent it to your email last week. Please let me know if you don't see it and I can send it again.

Thanks,

0 Moises Garcia over 7 years ago in reply to Mehrdad Bradaran

TI__Mastermind 23815 points

Hi Merhdad,

I saw the images you sent, that's why I new you had lane and polarity swap.
To conduct proper review that portion of the schematic is not enough, could you send the full layout or at least an image with all the components involved with TMDS181?

Regards

0 Mehrdad Bradaran over 7 years ago in reply to Moises Garcia

Intellectual 430 points

Hi Moises,

I just emailed you the schematic for this potion of the design. Can you please confirm if their connections are correct?

Thanks,

0 Moises Garcia over 7 years ago in reply to Mehrdad Bradaran

TI__Mastermind 23815 points

Hi Mehrdad,

I have reviewed your schematic this are my comments:

In DDC you have both connections snoop mode and DDC on, which resistors are not populated R1/R3 or R10/R11?
In DDC on R2/R4 should be 2k

Resistors in control pins should be 65k, which configuration are you using? which resistors are being populated?
If the environment is very noisy you may need to add 1uF capacitor on each control pin.

Will you use GPIO or I2C mode? you may need 2k pull-ups to 3.3V on SCL_CTL/SDA_CTL

For each power supply add a pair of 4.7pF and 10pF.

Regards

0 Moises Garcia over 7 years ago in reply to Moises Garcia

TI__Mastermind 23815 points

Hi Mehrdad,

To have Lane swap and polarity swap you need to configure it via I2C, so 2k pull-ups in SCL_CTL/SDA_CTL are needed and a controller to configure it.
Besides, polarity swap only works in retimer mode, you need to configure it in retimer mode across full range.

Regards

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TMDS181 Question