DP118 / DP120 for DisplayPort cloning

Martin,

This is not something that has been tested in the lab.  Typically, DP sources are designed to be only support a single load and by having two DP118, it will appear as two loads.  You really need a splitter, unfortunately TI does not have a splitter at this time.

Hello,

I know that this is not the common way, but I think it could work. Its a pitty that the 50R termination resistors are integrated in the chip. With two DP sinks at one source I think the signal amplitude will be cut to half. But even so the DP118 should be able to amplifiy the signal again.

Do you think the DP200 is the better solution? But the chip needs to be connected to the AUX channel and maybe its not possible to connect two chips to one AUX channel.

Regards,

Martin 

Greetings -

Depending upon a few system details, it might be possible to insert one of the "LVDS" type Crosspoint devices to split the data path and to make to a copy.  This would isolate the link into three different point-to-point links, and the electrical compatibility and terminations would need to be worked out of course. 

Two system considerations are: is the link unprotected data?  If protected content, then HDCP is also required and the link repeater / duplication becomes more complicated fast.  Also, DisplayPort can be 1, 2, or 4 lanes wide, so that would be another consideration along with data rate.  The AUX line is not addressed in this approach, just the serial data lines. 

Suggest a look at the LVDS_Crosspoint family

If only a 1 lane DP application, a 2x2 crosspoint could give a 1:2 function assuming the host and target and electrically compatible.

If a 4 lane DP application, a 8x8 could give the "quad 1:2" function assuming the host and target and electrically compatible again.

If data rate is less tham 4G, see SN65LVCP402 or SN65LVCP408.

John Goldie
DPS / SVA / www.ti.com

The solution is running a few years now. But only with DVI as the DisplayPort host and monitor needs bidirectional communication via the AUX channel.

DVI is simplier here with the monitors just displaying what they get.

Hi Martin,

Could you provide more information about the solution you implemented?

Are you using lvcp408? is this a dongle application? how do you connect AUX channel?

Regards

Hi Martin,

So you are not using AUX/DDC at all?

If this is the case DVI/HDMI send a default resolution when there is no DDC, however SDA from DDC is bidirectional too.

Have you tried using DP130(DP120) configuring it via I2C and using two lanes for each display?

You could connect one display to AUX and let the other just receive the video the first display supports.

We have TMDS442 to handle a similar scenario in HDMI/DVI.

Regards

Yes, we are connecting AUX/DDC to the first monitor and therefore all data comes from this display.
The second (clone) monitor has no AUX/DCC connection and therefore just has to handle with the data it gets. I.e. the display must be compatible with the resolution that uses the first monitor. Our customer simply uses two identical displays.

Fact is that with DisplayPort it is not so easy because the second monitor will not switch on without AUX channel communication. So leaving the AUX pins open results in a second monitor displaying just nothing...

Ok, DDC SDA line is bidirectional but as there is only an EEPROM in the monitor that is read out by the DDC host, no electronic unit within the monitor "knows" that the DDC EEPROM was red out. It just starts displaying something when there is valid data on the DVI lines.

TMDS442 I do not know. The project is rather old now, I just wanted to answer my old post to share the outcome with others.

Thanks for sharing your application Martin, we really appreciate.

Regards

You're welcome. I'd like to give something back, as imho you all do a great job at TI -- your website is outstanding, your parametric search is superb and it seems you really understood what data handling means in the 21st century. (: