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Display-switch: Turn a $30 USB switch into a full-featured multi-monitor KVM

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Re: Display-switch: Turn a $30 USB switch into a full-featured multi-monitor KVM

#51

Post by scruple »

walrus01 wrote: post #15

from a purely software perspective and sort of the inverse of this, everyone should be aware of barrier, the fork/continuation of synergy https://github.com/debauchee/barrier the general concept is you could have 2, 3, 4 or more individual desktop PCs at one desk, each connected to their own displays, and one keyboard and one mouse. The keyboard and mouse are on the primary workstation, you can roll the mouse off the…

I've been a happy synergy customer for about a decade now, I suppose but I didn't know about barrier. Thanks!

Re: Display-switch: Turn a $30 USB switch into a full-featured multi-monitor KVM

#52

Post by amelius »

lardo wrote: post #39

I control my monitor from a pi zero hooked up to a cheap vga/usb switch. If your monitor supports ddc/ci, ddcutil makes communicating over hdmi dead simple. The button from the usb switch, as well as a wire from the switch's chopped off vga cable is fed into gpio, as is a 4x4 input pad I use to control it from. Pressing D on the pad toggles displays and triggers the USB switch, A50# sets the volume to 50%, B50# brigh…

> The big downside is that switching inputs on my monitor takes ~5 seconds where a proper kvm would be instant.

This is something the industry should address. It's ridiculous.

Re: Display-switch: Turn a $30 USB switch into a full-featured multi-monitor KVM

#53

Post by mfwit »

intrepidhero wrote: post #49

Neat! Similarly, I've been using ddcutil on Linux and a stupid python script on Windows to switch video inputs. Janky as it is, it's more reliable than any KVM I've ever used, and I've tested quite a few. Now for my 2022 project I want to build one those promicro/QMK based custom keyboards with a direct I2c connection to my monitor and control it via hot keys. Eventually I'd add promicros for each computer all talkin…

Very interested in your QMK approach!

Re: Display-switch: Turn a $30 USB switch into a full-featured multi-monitor KVM

#54

Post by zbrozek »

rektide wrote: post #19
nkrisc wrote: post #14

Speaking from experience, download a program that can show what DDC commands your monitor supports before you bother. Mine supports many except… switching inputs (0x60 if I recall). Documentation for most consumer monitors is pretty lacking in this regard, it seems to be a feature mostly on monitors targeted to the professional market.

I was pretty shocked that most of the ddcutil & other similar programs on Linux weren't working for two of my monitors. The utils couldn't even detect the DDC display. But I told it what i2c bus to send to & what commands to issue, and it turns out my monitors had a pretty wide range of commands. Reminds me of an i2c motor controller I bought years ago, based off some avr microcontroller. I spent an afternoon trying…

Before we get that deep down on monitor tech, I want review sites to tell me whether I can use the monitor/tablet/phone/laptop with sunglasses.

Re: Display-switch: Turn a $30 USB switch into a full-featured multi-monitor KVM

#56

Post by yesenadam »

artemisbot wrote: post #9
mathfailure wrote: post #3

I've read the project's description and failed to figure what it does. What's a 'USB switch'? Where should this device be connected to? "press one button on your USB switch and all your monitors connect to a different input." - if the USB switch has buttons - why would I even disconnect/reconnect it? The project's description is shit.

If you actually sat and read it, you'd see that it's a piece of software that sits on each device connected to the USB switch and detects the USB disconnect/reconnect events which trigger when the USB switch is triggered and uses them to detect that the device should try to take control of the display devices.

> If you actually sat and read it, you'd see that

Without this phrase, your comment would be far friendlier and also not break the HN guidelines.

Re: Display-switch: Turn a $30 USB switch into a full-featured multi-monitor KVM

#57

Post by coryrc »

alufers wrote: post #45
rektide wrote: post #19

Earlier quoted context omitted.

I was pretty shocked that most of the ddcutil & other similar programs on Linux weren't working for two of my monitors. The utils couldn't even detect the DDC display. But I told it what i2c bus to send to & what commands to issue, and it turns out my monitors had a pretty wide range of commands. Reminds me of an i2c motor controller I bought years ago, based off some avr microcontroller. I spent an afternoon trying…

Sometimes it also the availability of commands depends on the cable/adapter used. If I connect my monitor directly via HDMI to my laptop I can send all the DDC commands I want, but when I use an USB-C -> DisplayPort cable ddcutil couldn't event detect the monitor. Sadly I must use this cable, because it's the only way I can get 4K@60FPS.

If you want to hack, you should be able to connect to the i2c directly on the monitor end.

Re: Display-switch: Turn a $30 USB switch into a full-featured multi-monitor KVM

#58

Post by Waterluvian »

Won’t this have a painfully long delay as the monitor negotiates the different input port?

Not only does every monitor I’ve owned take seconds to do this, it often screws with the desktop layout and such when display devices seemingly come and go. Or am I misunderstanding this?

Re: Display-switch: Turn a $30 USB switch into a full-featured multi-monitor KVM

#59

Post by gsich »

Waterluvian wrote: post #58

Won’t this have a painfully long delay as the monitor negotiates the different input port? Not only does every monitor I’ve owned take seconds to do this, it often screws with the desktop layout and such when display devices seemingly come and go. Or am I misunderstanding this?

No, all monitors I have used are connected (as in the OS sees the monitor) even if not the current active input.

Re: Display-switch: Turn a $30 USB switch into a full-featured multi-monitor KVM

#60

Post by anonymousiam »

Thanks for posting this! I did not know that I had control of my monitor features this way. My LG 27UK850-W reports the following capabilities when queried. (First I ran "ddcutil detect" to see what it said.)

Invalid display

   I2C bus:             /dev/i2c-15

   EDID synopsis:

      Mfg id:           LGD

      Model:            

      Serial number:    

      Manufacture year: 2013

      EDID version:     1.4

   DDC communication failed

   This is an eDP laptop display. Laptop displays do not support DDC/CI.
Display 1

   I2C bus:             /dev/i2c-17

   EDID synopsis:

      Mfg id:           GSM

      Model:            LG HDR 4K

      Serial number:    

      Manufacture year: 2018

      EDID version:     1.3

   VCP version:         2.1
So knowing that my LG monitor is display device #1, I then ran "ddcutil -d 1 capabilities"

MCCS version: 2.1

VCP Features:

   Feature: 02 (New control value)

   Feature: 04 (Restore factory defaults)

   Feature: 05 (Restore factory brightness/contrast defaults)

   Feature: 08 (Restore color defaults)

   Feature: 10 (Brightness)

   Feature: 12 (Contrast)

   Feature: 14 (Select color preset)

      Values:

         05: 6500 K

         08: 9300 K

         0b: User 1

   Feature: 16 (Video gain: Red)

   Feature: 18 (Video gain: Green)

   Feature: 1A (Video gain: Blue)

   Feature: 52 (Active control)

   Feature: 60 (Input Source)

      Values:

         0f: DisplayPort-1

         10: DisplayPort-2

         11: HDMI-1

         12: HDMI-2

   Feature: AC (Horizontal frequency)

   Feature: AE (Vertical frequency)

   Feature: B2 (Flat panel sub-pixel layout)

   Feature: B6 (Display technology type)

   Feature: C0 (Display usage time)

   Feature: C6 (Application enable key)

   Feature: C8 (Display controller type)

   Feature: C9 (Display firmware level)

   Feature: D6 (Power mode)

      Values:

         01: DPM: On,  DPMS: Off

         04: DPM: Off, DPMS: Off

   Feature: DF (VCP Version)

   Feature: 62 (Audio speaker volume)

   Feature: 8D (Audio Mute)

   Feature: F4 (manufacturer specific feature)

   Feature: F5 (manufacturer specific feature)

      Values: 00 01 02 (interpretation unavailable)

   Feature: F6 (manufacturer specific feature)

      Values: 00 01 02 (interpretation unavailable)

   Feature: 4D (unrecognized feature)

   Feature: 4E (unrecognized feature)

   Feature: 4F (unrecognized feature)

   Feature: 15 (unrecognized feature)
      Values: 01 06 09 10 11 13 14 28 29 32 44 48 (interpretation unavailable)

   Feature: F7 (manufacturer specific feature)

      Values: 00 01 02 03 (interpretation unavailable)

   Feature: F8 (manufacturer specific feature)

      Values: 00 01 (interpretation unavailable)

   Feature: F9 (manufacturer specific feature)

   Feature: E4 (manufacturer specific feature)

   Feature: E5 (manufacturer specific feature)

   Feature: E6 (manufacturer specific feature)

   Feature: E7 (manufacturer specific feature)

   Feature: E8 (manufacturer specific feature)

   Feature: E9 (manufacturer specific feature)

   Feature: EA (manufacturer specific feature)

   Feature: EB (manufacturer specific feature)

   Feature: EF (manufacturer specific feature)

   Feature: FD (manufacturer specific feature)

      Values: 00 01 (interpretation unavailable)

   Feature: FE (manufacturer specific feature)

      Values: 00 01 02 (interpretation unavailable)

   Feature: FF (manufacturer specific feature)quirred
So I pretty much have control of all monitor features!
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