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Forum Index : Microcontroller and PC projects : CMM2 via VGA-Hdmi Converter to KVM-Switch

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Wolfgang
Regular Member

Joined: 03/11/2021
Location: Germany
Posts: 87
Posted: 07:37am 08 Mar 2026
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Hallo experts,

I apologise if I am possibly revisiting an old topic here.


I would like to use my monitor for both tasks: HDMI (from my PCs) and also the CMM2-VGA via my KVM switch.

My KVM switch has HDMI-video inputs, so a VGA-HDMI converter could be connected between KVM-switch and the CMM2.

Has anyone tried connecting a CMM2 to such a KVM switch (HDMI inputs) via a VGA-HDMI adapter for using only one monitor? Does this makes sense, or are there any reasons not to do so?

Wolfgang
 
Mixtel90

Guru

Joined: 05/10/2019
Location: United Kingdom
Posts: 8650
Posted: 08:23am 08 Mar 2026
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Awww... And I was so looking forward to ordering a MicroMite Plus.  ;)

I must confess that I've not used a VGA to HDMI converter, only the other way so that I could use an old monitor with a Raspberry Pi.

I think your idea will *probably* work, after all VGA is a very basic linear system. The converter from VGA to HDMI should be taking care of everything to make the signal HDMI compatible. After that the KVM is merely switching the signals.

I suspect that, if you have any problems, it will be with your monitor re-synchronising to a different resolution. That can sometimes be a bit slow.

There is also the case that the VGA-HDMI converter will almost certainly have to be a "proper" active one and not a very cheap Chinese knock-off which might or might not work. They aren't that expensive now anyway.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
Volhout
Guru

Joined: 05/03/2018
Location: Netherlands
Posts: 5753
Posted: 09:17am 08 Mar 2026
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The mouse on CMM2 is PS2, not USB, despite the USB connector. You need a converter to run it through a KVM switch.

Volhout
PicomiteVGA PETSCII ROBOTS
 
Wolfgang
Regular Member

Joined: 03/11/2021
Location: Germany
Posts: 87
Posted: 09:18am 08 Mar 2026
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at the moment, my monitor is cycling through all four video inputs before finally displaying the VGA connection. This thake some time.

Could this be resolved with an EDID function on the VGA-HDMI converter?

Would it be possible to set the CMM2-VGA pin 9 to +5V or to use an EDID emulator for this purpose?
 
Mixtel90

Guru

Joined: 05/10/2019
Location: United Kingdom
Posts: 8650
Posted: 09:35am 08 Mar 2026
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I've no idea. VGA has no equivalent of EDID so it would be a function of the converter, which may or may not handle VGA pin 9. You probably need a full specification of the converter. Good luck with that unless you are getting a big name commercial one.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
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