Using a Laptop as an HDMI Monitor for an SBC

https://danielmangum.com/posts/laptop-hdmi-monitor-sbc/

47•hasheddan•3h ago

Comments

kevmo314•2h ago

Since there’s monitors that work over USB-C, could one replace the capture card and somehow get the laptop to pull video like a USB-C monitor?

detaro•1h ago

not really. The video stuff needs explicit hardware support, so the laptop would need to include what's essentially a capture card already. It'd be awesome if vendors did that, but to my knowledge nobody does.

05•2h ago

I'm thinking a better solution for console would be an SSH to serial bridge using just a spare ESP32 and something like ESP32SerialSSHProxy[0]. Haven't tried myself yet, and there is suspiciously few stars on that repo, but that would be a nice lights out-ish management system for some hidden away home automation server.

[0] https://github.com/programminghoch10/ESP32SerialSSHProxy

jonathanberi•2h ago

That works sometimes. It can be flaky.

hasheddan•1h ago

You can also throw together a cheap software KVM switch[0] using an ESP32 or similar.

[0] https://euer.krebsco.de/a-software-kvm-switch.html

thesandlord•2h ago

If you have an iPad with a USB-C port, you can use the free Orion app to do this too

https://orion.tube/

rahimnathwani•1h ago

My son uses the Genki Studio app on his iPad. It works well enough without payment.

https://apps.apple.com/us/app/genki-studio/id6466343285

I don't know how Orion compares.

The home page says the one-time IAP unlocks 'AI-powered 4k upscaling', which sounds useful.

dylan604•28m ago

> The home page says the one-time IAP unlocks 'AI-powered 4k upscaling', which sounds useful.

To what end? For displaying on a tablet only? Does it provide screen capture to save that 4k version?

rahimnathwani•11m ago

iPads have high resolution screens.

Cheap USB capture devices usually support a maximum of 1080p@60Hz output. If you buy a random '4k' USB capture device, it probably supports up to 4k input but then scales it down to 1080p for output.

So perhaps 4k upscaling on the ipad will make the image look better.

MBCook•9m ago

I did that just last week to install Linux on a micro-PC I have. It’s only display output is HDMI and I didn’t want to unplug it and move it over to my TV just for the short time necessary to install a base system + SSH.

Worked great!

I’ve used the app for other things too. It’s a great solution if you already have an iPad.

CYR1X•1h ago

Yes, $5 USB HDMI capture cards exist?

actionfromafar•1h ago

Usually slow

gsich•46m ago

In what regard? The common Macrosilicon chip MS2130 has <100ms.

actionfromafar•44m ago

10 fps isn’t great, latency wise. Even typing or using a mouse is very clunky.

I may have been unlucky, but I have seen even worse.

jsheard•9m ago

Even a higher framerate isn't any guarentee of low latency, most HDMI capture devices have 50-80ms of lag even when capturing at 60fps.

https://youtu.be/lhBwJGhJyDM?t=142

dlcarrier•1h ago

There's off-the-shelf semiconductors that perform the conversion in hardware, so all the dongles need is a simple breakout board for the component.

frankus•1h ago

This would have been super helpful like 20 years ago when I was on the data center floor trying to debug rack-mount (headless) Linux servers. The center had like one KVM "crash cart" that needed to be plugged into a spare outlet in the rack that wasn't always easy to come by.

I'm sure we could have improved on that setup but we were an inexperienced skeleton crew on a shoestring budget and not the best management.

I always thought it would be great to have a "laptop without a motherboard" to manage these, and this is close enough given the price of the redundant hardware now.

Havoc•1h ago

You can do similar with an Android tablet and a usb adapter

hard_times•1h ago

is there no vendor offering HDMI-in or Display Port-in?

EnigmaCurry•1h ago

GPD Pocket 4

jollyllama•1h ago

It always used to baffle me that there wasn't support for this (or the historic equivalent) 20 years ago.

dylan604•26m ago

20 years ago it would have been prohibitively expensive.

theallan•58m ago

The Minisforum V3 does: https://store.minisforum.com/products/minisforum-v3 .

belthesar•1h ago

For use cases like attaching to an SBC or really any other computer, I'm sure this is great, but there are also USB crash cart consoles that can be gotten pretty cheaply like the NanoKVM-USB[0] or Cytrence's KIWI[1]. This gets you both video, keyboard and mouse.

[0] https://wiki.sipeed.com/hardware/en/kvm/NanoKVM_USB/introduc...

[1] https://www.cytrence.com/product-page/cytrence-kiwi

rahimnathwani•4m ago

Is there anywhere I can buy a NanoKVM-USB? The page you linked has a 'preorder' page linked, but I'm not sure how long I'd have to wait and whether it's an actual product that people have successfully used.

jmmv•1h ago

> digging up an HDMI monitor, finding somewhere to put it, and connecting it to the device is an annoying process. Furthermore, if I’m on the go I almost certainly don’t have easy access to an external monitor.

This has annoyed me many times as well with the headless computers I run... until recently, when I bought a USB-powered 7-inch HDMI monitor for an embedded project that didn't go anywhere. But now I have a spare little monitor that I can easily use in these situations and even carry it around if necessary.

blensor•36m ago

You may be interested in this then https://github.com/mgschwan/viture_virtual_display

Or now that I think of it, just use the glasses with a regular hdmi adapter ( but no 3dof tracking then )

asplake•55m ago

Anyone using a Intel iMac as a monitor for their much faster Apple CPU MacBook Pro? Wishing “target display mode” was still a thing…

crumpled•36m ago

I saw a video of this guy (the github project author) using the Lilygo T-deck as a VNC console. It's a fun looking solution, but it requires wifi.

https://github.com/moononournation/T-Deck/blob/main/ArduinoV...

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