Posted by Michael Posner on May 2nd, 2014
This week I was asked to clarify what the PCIe Gen3 protocol speed is, to confirm, PCIe Gen3 speed is 8Gb/s per lane. PCIe Gen 1 is 2.5Gb/s and PCIe Gen2 is 5Gb/s. Yes I know I’m usually seen as the prototyping guy, (Or Mick “I’m not dead yet” Posner thanks to my pneumonia) but I also happen to double up as a protocol expert. One of the key advantages of FPGA-Based prototyping is the ability to model real world interfaces at speed so to be a prototyping expert you basically have to be a protocol expert as well. The above eye diagram (click image to view full size) is measured on the HAPS-70 (-2) speed grade systems running one of the many DesignWare PCIe Gen3 controller validation tests for interoperability and compliance testing. That is a good looking wide open eye!
I sneaked into the lab and snapped off this picture. (Click on image to view full size)
The little HAPS-70 S12 (-2) speed grade system is perched on top and that large black cable sticking out is the PCIe Gen3 capable cable connection. The cable plugs into a PCIe Gen3 host adapter board that in turn plugs into the host machine. In this specific setup I was told that we have the DesignWare PCIe Gen3 End Point controller modeled in a x4 lane configuration. Yes that’s x4 lanes of PCIe Gen3 so x4 lanes of 8Gb/s. I’m going to try and have the R&D engineer do a little video for me of the system in action as it was very impressive.
Oh, when using the Xilinx built in transceivers (Rocket IO) as the physical link the (-2) speed grade systems are required to model PCIe Gen3. The (-1) Xilinx Virtex-7 2000T devices only support up to 6.6 Gb/s while the (-2) support up to 10.3125 Gb/s thus supporting PCIe Gen3 speeds. Looking for PCIe Gen3 expert advice, go check out the Express Yourself blog
Off topic, spring has sprung in Oregon !! Yay, it was here for a whole 4 days and now we are expecting rain again. This is fine, this is what you expect and grow to love when living in Oregon. The mix of sun and rain makes everything really green, just look at how beautiful this little baby fern is. This is growing in my yard along with a huge amount of moss which is also typical across Oregon.
Click on image to view full size