Anyone built a Pi-KVM? HDMI/CSI adapter question

TangoEchoAlpha · 1 Sep 2021 at 13:41

Wondering if anyone has built a Pi-KVM on the forums? I am thinking about it as a project, so I could VNC into my work laptop from my main computer. Really it has to be a KVM solution as I can't install any extra software/run any software on the work laptop.

I'd be very interested if anyone has done it - in particular, which HMDI to CSI-2 bridge you used. The official docs suggest to use a HDMI/CSI adapter based upon the Toshiba TC358743XBG chipset and links to an adapter on AliExpress. I would rather buy an adapter/bridge more locally if I can and was wondering if something like the Waveshare HDMI to CSI adapter on the rainforest would work?

Or can I use any CSI/HDMI adapter? If anyone can suggest one to get from the usual Pi places, would be very grateful

TangoEchoAlpha · 3 Sep 2021 at 09:07

jrwagh333 said:
Have you taken part in the Kickstarter for the HAT? Looks great.

I'd seen it, but not backed it yet. Have you put in a backer pledge then?

TangoEchoAlpha · 3 Sep 2021 at 09:17

jrwagh333 said:
Unfortunately it's too rich for my blood. I'm going to try and do it DIY

Yes, I felt the same. I'll quite happily donate / Patreon the Pi-KVM project if it turns out to be something I find useful, but felt that HAT was a bit pricey. Same for the TinyPilot, great idea but also more than I'd like to spend on a home KVM. I guess relatively speaking though, it's still cheap compared to a 'proper' IP KVM.

TangoEchoAlpha · 3 Sep 2021 at 19:13

@jrwagh333 I have just ordered one of these:

https://www.ebay.co.uk/itm/USB-C-PWR-Splitter-/203570218304

As Pi Hut and Pimoroni were sold out. Looks like one guy making them and perhaps the interest in Pi KVM of late has used up all his stock?

I've also got a HDMI/CSI2 adapter, went for the Waveshare one - so once the splitter arrives I should be in a position to try it out

TangoEchoAlpha · 4 Sep 2021 at 17:07

Buffalo2102 said:
I guess it should be OK since OCUK don't sell anything like it.

https://www.amazon.co.uk/dp/B095KJ2181?ref_=pe_27063361_487360311_302_E_DDE_dt_1

Thanks for that link, of course it would be cheaper than the one I ordered - https://www.amazon.co.uk/gp/product/B08TBD68MH

Looks like exactly the same item :confused:

TangoEchoAlpha · 4 Sep 2021 at 17:25

Buffalo2102 said:
It's gone up since I bought it too.

Thought I'd chance my arm with an Amazon chat, see if I could get a credit for the difference. Nope, but they would be happy for me to return the one I have and place a new order with the cheaper one. Sadly common sense with Amazon policies did not take place

TangoEchoAlpha · 4 Sep 2021 at 17:33

Buffalo2102 said:
Nice try though.

I did make the point about the cost to Amazon in terms of processign the return and a new order, even played the 'environmental impact' card. Customer rep wasn't having any of it, be he's good at poker is all I'll say

What solution did you use for powering your Pi-KVM? I was getting ready to splice two cables together, but if that power adapter arrives then it might be a more elegant solution for not a lot of cash.

TangoEchoAlpha · 4 Sep 2021 at 17:48

Buffalo2102 said:
I bought one of these - https://www.amazon.co.uk/dp/B07DS2RJY1/ref=pe_27063361_487055811_TE_dp_1

Then cut the power to the USB data leg. You could just tape over the power conductor in the connector but I though that was too fiddly and too unreliable.

Do you not get any low current warnings on your Pi? I ask as I had looked at other similar Y cables, but couldn't find any that were rated for ~3 amps like the official Raspberry Pi 4 power adapter?

The Pi-KVM project also recommends one of these if you don't want to start hacking cables, like a data 'condom' to prevent juice jacking, but this one removes the power pins - https://www.amazon.co.uk/PortaPow-USB-Power-Blocker-Cased/dp/B094FYL9QT

TangoEchoAlpha · 4 Sep 2021 at 17:57

Buffalo2102 said:
I get an amber warning for undervoltage detected but I've been using it for around 10 hours a day, 5 days a week for more than a month now and haven't had a single hiccup with it. YMMV I guess.

Thanks, useful to know. Will wait and see if that £3 adapter turns up, otherwise I'll get a Y cable or get my soldering iron out (probably the latter)

TangoEchoAlpha · 5 Sep 2021 at 18:56

@jrwagh333 The USB C adapter is back in stock on Tindie

https://www.tindie.com/products/8086net/usb-cpwr-splitter/

TangoEchoAlpha · 6 Sep 2021 at 00:59

Buffalo2102 said:
I built one to use in the same way as you - remote into work laptop which is completely locked down.

I used the Waveshare adapter you mention above and it works well.

Do you have any recommendations for cases/what case did you use for your Pi KVM?

There is one I found on Thingiverse, which also takes the USBC/PWR adapter that I've ordered, so it good option, aside from the fact it has PI KVM cut out of the top lid as text. Otherwise, nothing obvious is juming out at me, given I'd like all of the parts enclosed.

TangoEchoAlpha · 6 Sep 2021 at 17:46

Buffalo2102 said:
No, I'm still looking myself. I currently have a simple perspex case with the adapter resting on top.

If I can't find anything I like by next weekend I'll probably get my dremel out and try and be creative.

The two most hopeful options I have found are the Argon Neo (which would require a bit of Dremel/hacksaw for the HDMI port) or the LeapMatic MaticBox, with the automation lid fitted and then trimming the automation screen (slot in piece of plastic) down to size for the HDMI port to fit.

I've got both on order with Pi Hut and will keep whichever out of the two looks most promising. Failing that I came up with a few possibilities on Thingiverse:

https://www.thingiverse.com/thing:4832248
https://www.thingiverse.com/thing:4942260

The latter would be my preferred option, as it has a cutout for a fan. I'm not a fan of the cut out 'Pi KVM' text though and am not skilled enough with any kind of modelling software to remake it with that cut out text filled in!

Also this chap https://ericlathrop.com/2020/12/my-pi-kvm-build/ suggests using one of the acrylic 'set-top cases' as they come wtih full size HDMI cutouts, but then not using the daughterboard that comes with those kits.

I would be interested to hear what you end up going with / doing

TangoEchoAlpha · 6 Sep 2021 at 21:37

Buffalo2102 said:
Yea I'll post in here when I've sorted something out.

Thanks for the links - I'll take a look later.

This one looks even better (IMO) and has a variety of options for the bottom and top.

https://www.thingiverse.com/thing:4931970

TangoEchoAlpha · 7 Sep 2021 at 20:45

I wouldn't bother with the MaticBox - the automation opening is completely the wrong side for an HDMI port. It would work if you could mount the adapter vertically, with the HDMI port on its side, but the lid won't close then because of the size of the PCB.

I have been messing around with a 3D model for an Argon Neo and asked in the 3D printing section if someone would be able to check my model for errors, as I've been editing a model from Thingiverse and I'm a complete noob when it comes to 3D modelling/CAD etc

TangoEchoAlpha · 9 Sep 2021 at 11:18

Buffalo2102 said:
......at least the adapter isn't just hanging off the ribbon cable anymore.

That's what has concerned me the most about not having some kind of solution. I am hoping that the 3D parts I've had printed for the Argon Neo will arrive over the next day or two and I can see if it all works.

TangoEchoAlpha · 10 Sep 2021 at 18:44

Woo-hoo! Got the case put together, with a lot of thanks to @andy_mk3 who made some changes to the CAD model I got from Thingiverse. Sadly the HDMI port was about 3mm out when I got it printed (down to the original Thingiverse model, not the printing), so if I was going to do another I would make a change to the model and move the HDMI port 3mm inwards. In the end I just took out a little bit of the FDM with a very sharp craft knife.

Due to the lid being very shallow, the HDMI/CSI adapter has to be held in place with some electrician's tape - even the heads of some M2.5 nylon screws, from my Pi box of tricks were too tall!

Original Argin Neo case:

New case lid:

And this is a print of a little case for the USB-C power/data splitter from Thingiverse. If I get the case reprinted, I might do it to match this little adapter case:

Very pleased with the printing of the adapter case especially. Printed with clear blue SLA.

TangoEchoAlpha · 14 Sep 2021 at 15:43

Buffalo2102 said:
I got a usb-c power/data splitter off ebay in the end - £4.29. No power warnings now.

Sweet, one of the 8086 Consultancy ones?

I'm really pleased with how PiKVM is working out and supported the project via Patreon. I feel that the piKVM HAT is too rich for my liking, but I am going to be using PiKVM almost daily, so wanted to support it. I haven't tried it yet, but if I could get a USB webcam working over the KVM as well, that would be amazing. Not sure if it's possible though, should try it and see what happens!