I'm looking to build a simple board that has a 16x PCIe connector, that seats a compatible PCIe video card.
I can find the connectors and create a footprint, on the board. I can find and understand to some degree the basic pin-out of the PCIe 1x connector — but I'm not clear on the full end to end implementation.
I've read the full specifications costs lots of money, and honestly is overkill for what I want.
I'm not super concerned about the actual protocol (like at the physical layer), so not necessarily looking for the official PCIe spec — just the nuts and bolts implementation. Which pins go where on the cards, where they are laid out.
I am not certain on signal routing both between the mating connector and the PCIe card, and then where the card signals.
I know Altium provides templates of the actual pads and so on, but I'm more interested in where the signals go, and what each one does, and which signals need to be treated as high-speed signals and so on.
It seems like this kind of information isn't so open-source? It's not like a video manufacturer is just posting up a datasheet for every person who buys a PCIe card to understand how it is routed from card to the eventual CPU on a motherboard.
For people who are building video cards or whatever for PCIe, where do they learn how to build these devices?