DisplayPort Multi Stream versus Single Stream: What is the difference?

DisplayPort is the latest display technology on the market and is generally considered to be a competitor to HDMI.  The VESA specification which describes the DisplayPort Technology lists two types of transport modes.  The first is SST or Single Stream Transport.  The second is MST or Multi Stream Transport. What’s the difference between DisplayPort SST and DisplayPort MST? SST is Single Stream Transport mode so it can only handle one downstream device. For MST the link is divided into Virtual Channels and each of those Virtual channels is made up of Time Slots.  The link can have up to 64 (0 to 63) Virtual Channels and 64 Time Slots.  So at a maximum each Virtual Channel could be made up of 1 Time Slot and you could have 64 of them.  A Time Slot is a single Link Symbol Cycle, which for 8b10b (which DisplayPort is), equates to 10 clock cycles on the bus. Basically, you can think of Mulit Stream as streams of video data that are time multiplexed.  Each virtual channel can target a different monitor downstream from the source.  We like running Multi Stream in our lab with several down stream monitors. Figure 1:  MST setup with the FuturePlus Systems FS4500 DisplayPort Protocol Analyzer on an MST Link So what does the MST Traffic really look like?  Traffic between the source (the motherboard or graphics card) and the Sink (the monitor) consists of 2 different busses.  The first is the Aux Channel which handles low speed configuration information.  The second is the one way, Source to Sink, super highway of sorts called the High Speed Main...

Got DisplayPort?

Calling all DisplayPort Developers.  FuturePlus Systems will be at the next VESA DP PlugTest Nov 13-17 in Burlingame CA.  Sign up for a test session and see how your DP design performs with real life DP sources and sinks.  All test results are yours to take with you.  We can support regular DP and USB Type C connectors at data rates up to and including HBR3.  Can’t make the PlugTest?  Contact us!  Perhaps we can visit your...
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