UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

cancel
Showing results for 
Search instead for 
Did you mean: 
Participant xxhc417s
Participant
1,211 Views
Registered: ‎12-02-2016

Displayport Rx AUX channel termination

Hi, 

  My custom board has Displayport Rx, the AUX channel is connected to 2.5V HR bank. As per VESA DP standard, AUX needs AC coupling and DC bias. The board uses 100nf for AC coupling, and 50 ohm resisters  pullup to 1.25V at FPGA side.

When I probe the aux chanels, the waveform is strange, data packet's voltage amplitude is not the same. Does this  related to incorrect terminations?

 

 

wave.png
0 Kudos
10 Replies
Moderator
Moderator
1,127 Views
Registered: ‎11-09-2015

Re: Displayport Rx AUX channel termination

Hi @xxhc417s,

 

Yes it might be a wrong termintation. You might want to check the Inrevium DP FMC card for a compliant solution


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
0 Kudos
Participant xxhc417s
Participant
1,113 Views
Registered: ‎12-02-2016

Re: Displayport Rx AUX channel termination

Thankyou for your reply. I didn't have dp fmc card, instead the schematic about aux termination is the same as ug417 fig. 1-72 without on board Rdiff=100Ω(use on chip 100Ω)。GPU can read edid through aux channel。Can you describe how the dp rx fmc card be terminated?
0 Kudos
Moderator
Moderator
1,035 Views
Registered: ‎11-09-2015

Re: Displayport Rx AUX channel termination

Hi @xxhc417s,

 

The termination on the FMC card is as documented in the FMC card:

1MOhm pull pup -> capacitor -> 50 ohm register followed by a level shifter.

 

How are you doing the bidirectional? Is is internal to the FPGA or do you have an external buffer. Note that Xilinx mainly tested with external buffer (with unidirectional LVDS)


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
0 Kudos
Participant xxhc417s
Participant
1,024 Views
Registered: ‎12-02-2016

Re: Displayport Rx AUX channel termination

I use internel bidirectional instead of external levelshifter. The aux channel connection between connector and DP rx
: 1MOhm pull pup -> capacitor -> 50 ohm resister pullup to 1.25V then to FPGA HR bank.
Though the aux channel waveform is not good, GPU can read corrected EDID.



0 Kudos
Moderator
Moderator
1,019 Views
Registered: ‎11-09-2015

Re: Displayport Rx AUX channel termination

Hi @xxhc417s,

 

Could it be that your waveform analyzer is creating this floating waveform?

 

If GPU can access EDID, it might not be an issue.


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
0 Kudos
Moderator
Moderator
976 Views
Registered: ‎11-09-2015

Re: Displayport Rx AUX channel termination

HI @xxhc417s,

 

Do you have any updates on this?


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
0 Kudos
Participant xxhc417s
Participant
962 Views
Registered: ‎12-02-2016

Re: Displayport Rx AUX channel termination

Hi,

    There is no update about this topic. DP Rx still cann't work for which you can reference this. Now I'm checking the power supply that feeds to GTX. 

 

0 Kudos
Moderator
Moderator
605 Views
Registered: ‎11-09-2015

Re: Displayport Rx AUX channel termination

HI @xxhc417s,

 

Were you able to have your link working?

 

Regards,


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
0 Kudos
Participant xxhc417s
Participant
275 Views
Registered: ‎12-02-2016

Re: Displayport Rx AUX channel termination

Hi,

  No, the board still can not work. I will keep updating.

 

Best Regards,

0 Kudos
Scholar watari
Scholar
266 Views
Registered: ‎06-16-2013

Re: Displayport Rx AUX channel termination

Hi @xxhc417s

 

Would you share version of DP Rx and a schema around DP ?

Also, would you turn off SSC at GPU, if possible ?

 

BTW, can you receive VGA video timing via DisplayPort ?

It means that I'd like to confirm whether it works fine under RBR (1.27Gbps) or not.

 

Best regards,

 

0 Kudos