Multiple Monitor Support

This is aimed particularly at mobile devices with limited connector space.

Backwards Compatibility

Dual-mode DisplayPort (also known as DisplayPort++) can directly output single-link HDMI and DVI signals using a simple passive adapter that adjusts from the different connector and the lower voltages used by DisplayPort. When a DVI or HDMI passive adapter is attached the dual mode compatible chipset switches to DVI/HDMI mode which uses the 4-lane main DisplayPort link and the AUX channel link to transmit three TMDS signals, a clock signal and Display Data Channel data/clock. Dual-mode ports are marked with the DP++ logo.  However there are limitations in that this mode can't support dual-link DVI and is limited to 165MHz.

Most current DisplayPort graphics cards and monitors offer this mode.

AUX Channel

DisplayPort doesn't have the DDC based I2C port of previous display connectors (e.g. DVI, HDMI).  Instead it has a high-speed auxiliary (AUX) channel for DDC, EDID, MCCS, DPMS, HDCP, adapter identification etc. traffic.

~1Vpk-pk differential signal, AC coupled

Bi-directional signal path

Default “AUX” mode:

1 Mbps transfer rate (either direction)
Manchester encoded

“Fast AUX” mode (option defined by DP 1.2)

720 Mbps transfer rate (either direction)
8B/10B encoded
Includes link training

Hot Plug Detect Signal

Signal provided by the Sink (display) to the Source (GPU)

Typically 0V or 3.3V signal (bi-level).

“High” signal (3.3V) indicates Sink presence.

“Low signal (0V) > 2 ” signal (0V) > 2 msec indicates Sink absence

“Low” signal of 0.5 to 1ms indicates “interrupt” from Sink (request to read Sink DPCD registers)

Power Pin

DisplayPort Source and Sink receptacle includes a power pin.

Provides 3.3V at 500 mA (1.5W) (May include higher power option in the future).

Can be used to power:

Display Adapters (such as DP to VGA DVI HDMI) Display Adapters (such as DP to VGA, DVI, HDMI)
Active cables (for greater distance)
Hybrid cables (Fiber optics, etc.)
Display Hubs (for multi-monitor connection)
Pico projectors

We benefit hugely from resources on the web so we decided we should try and give back some of our knowledge and resources to the community by opening up many of our company’s internal notes and libraries through mini sites like this. We hope you find the site helpful.
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