After looking at some PiKVM “PCIe” cards which only use pcie power or sometimes don’t even connect to the board i got curious.
“How to build a full PCIe KVM Card where only a network cable connects externally?”
Power and Reset buttons got a fast “dismiss”. As far as i understand it, I²C doesn’t provide a Power Up only a Power Down. No Problem these Pins can be routed internally like current cards do it. (Maybe there is something else what could use WOL features in which i didn’t dive deep enough)
Power could come from PCIe, PoE or an external Plug. Coupled with a diode to block powering the MB over PoE would probably do the trick.
Keyboard and Mouse could go via internal USB header or have a build in USB to PCIe chip.
But video is where is struggle.
I don’t know of internal Video Ports, maybe they are a thing? But if not, the PCIe card would need to work as video out.
Is it possible to use an FPGA for this? Are their readily available GPU Chips or SOCs for low end devices?
Or in general is there a PCIe KVM using itself as a gpu? What are the challenges?
Is being a GPU in a pcie slot harder than simple powering a graphics engine providing HDMI signals?
I’m no engineer but i got curious and can’t get this out of my head, so i hope someone can kindly dismiss this thought process.
I think all of the blikvm/geekworm-type PCIe based iKVM options still use USB/internal header or PoE for power rather than getting the power from the PCIe port. Reason I assume is because the only stand-by power the PCIe slot provides is limited to 250mA @ 3.3v which isn’t enough for the relatively power hungry RPi.
The power and reset buttons need there own breakout header for maximum compatibility; but you’re right that a WoL implementation of power control should be able to be implemented assuming the correct BIOS settings were already applied to the computer.
I don’t think a diode would be necessary, if the iKVM system is getting power over PoE then it simply won’t pull any power from or have traces going to the 3.3/12v rails of the PCIe slot.
Almost ever single one of these iKVM cards requires external video input since the video output cannot be picked up from PCIe bus unless a video card was implemented in the iKVM itself, like some of the Aspeed solutions. But these Aspeed solutions seem to have lots of compatibility problems like the Asrock PAUL or the dedicated ASUS Aspeed card (to be fair to ASUS they don’t advertise it as working on any system without explicit BIOS support).
You’d never be able to run a even modest GPU implemented in FPGA on the standby power the PCIe port provides, but I suppose you could have the video portion of the iKVM initialize only after the PC powers on… but getting into GPU development is very heavy.
I’ve often wanted a powerful iKVM I could put into a PC so I could use it remotely and not have to rely on broken and buggy virtual desktop software (all of it is to varying degrees).
I think something like this is probably the best for my situation but I have yet to try it:
