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I have recently been given a PWAY 4 way KVM switch (Model PW-SH0401B) so I can use one screen/mouse/keyboard with 4 Raspberry Pi I am using for some research work. Although it works when I attach my desktop or my laptop, it will not seem to detect that the Pi is attached. Is this a HDMI issue as it states it is compliant with HDMI 1.4 standard but also that it supports maximum video resolution up to 4K x 2K @ 30Hz or lower. Any ideas?

Additional: Apologies for the rather vague and poorly worded question.

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  • May be also the Raspberry can not detect your KVM. You can force Raspberry to enable HDMI see here: raspberrypi.stackexchange.com/a/2171
    – Robert
    Jun 18, 2020 at 19:57
  • Not recognize how? keyboard, mouse, video all of the above? Jun 18, 2020 at 20:04
  • Steve, when selecting the channel into which the pi is plugged, the screen goes blank as there is no input signal. If I go back to my Linux desktop it is fine.
    – A Bingham
    Jun 18, 2020 at 20:09
  • Robert, thanks, I hadn't thought of that. Will give it a try
    – A Bingham
    Jun 18, 2020 at 20:11
  • Robert, you dancer! That appears to have done the job. Thanks for the help both of you.
    – A Bingham
    Jun 18, 2020 at 20:19

1 Answer 1

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By default the Raspberry only enables the HDMI port if at boot time a connected HDMI devices is detected.

Therefore it is possible that your KVM want's the Raspberry to make the "first step" and the Raspberry want's the KVM to do the first step.

To solve this issue you can configure your Raspberry to always enable the HDMI part at boot. Afterwards the KVM should be able to detect it.

To do do you have to modify /boot/config.txt (config.txt on the boot partition) and add the entry:

hdmi_force_hotplug=1

Additionally add the following entry to force the HDMI to HDMI mode (with audio):

hdmi_drive=2

For more details on the video configuration options see the documentation at raspberrypi.org.

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