¶ KVM over IP
Low cost standalone remote desktop.
¶ Architecture
PlantUML source
card ikvm [ iKVM ]card computer [
PC
]ikvm --> computer : USB OTG
ikvm <-- computer : HDMI/VGA
¶ Parts list
- ARM SbC that has USB OTG port for keyboard/mouse emulation
- ~15€ + 5€ SD Card
- USB HDMI capture dongle
- ~10€
- Optional VGA to HDMI converter box.
- ~5€
¶ ARM SbC
Possible canditates with USB OTG port are
-
- Costs around 10€ Aliexpress
- Has Wifi, 100Mbit ethernet
- One USB A port and One MicroUSB OTG port
- Well supported by linux-sunxi and Armbian
- Includes small SPI flash chip that allows it to boot without SD Card in the future.
- Wifi chip is really horrible and it is easier to pretend it does not exist.
-
- Similar to Orange Pi Zero
- but has no onboard wifi
- Has Better CPU cooler mounting options
-
Pretty much any other SbC supported by Armbian with OTG port also works here
-
- I have access to bunch of them.
-
Raspberry Pi 4
- Has USB-C OTG port
- Is power hungry and probably needs a separate PSU
¶ HDMI Capture
Recently a Really cheap USB 2.0 HDMI capture card came to market
It presents itself as a normal UVC webcam and should work with all modern systems.
Internally that dongle encodes everything as MJPG stream to fit FullHD videostream inside limited USB 2.0 bandwith. This can result in blury text and I recommend keeping the resolution equal or less than 720p for optimal usage.
¶ VGA to HDMI
Any VGA to HDMI converter box should work
¶ Software
¶ Streaming HDMI to a browser
Simplest way is to send the MJPG stream to the browser in a img tag and hope for the best
¶ Input to PC
Our SbC has to pretend to be a USB HID Keyboard and Mouse device
and get user input over WebSocket from the browser
¶ Previous work
- https://pikvm.org/
- Quite hevily tied to the Raspberry Pi.
- Supports mass storage emulatino
- Many features
- has ustreamer software that also works on other computers.
- https://tinypilotkvm.com/
- Alot simpler software
- https://zach.bloomqu.ist/blog/2020/08/pilo-raspberry-pi-lights-out-management.html
- Uses Arduino to emulate PS-2 keyboard