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Pre-boot display output on laptops, how to trigger

By @hicktastic
    2021-06-18 18:50:24.238Z

    Most laptops don't automatically use the TinyPilot as an external mirrored display during startup. It has to be triggered manually via keyboard command or some other function. On our laptops, they key command is 'Fn'+F8. I could not find a way to trigger that key command remotely however.

    Is it possible to send 'Fn'+F8 at all?

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    1. NO SIGNAL but keyboard and mouse are working
    • 4 replies
    1. Michael Lynch @michael2021-06-18 22:02:40.618Z2022-02-14 22:35:50.640Z

      Update (2022-02-14) - This is a bug

      See TinyPilot can't send KEY_SWITCHVIDEOMODE

      You should see F8 appear on the bottom of your screen when you push Fn+F8. Does this appear?

      The OS doesn't see the Fn key. It's just on your keyboard to let you press the F8 key. You can verify this by visiting keycode.info, which should show nothing happening when you press Fn by itself.

      Some laptops don't accept external keyboard input during boot. You can try testing a USB keyboard in the laptop to see if it accepts an F8 from the keyboard. If it doesn't work with a physical keyboard, TinyPilot won't be able to enter input either. You can also check the laptop's BIOS settings for options regarding keyboard or display during boot.

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      1. H@hicktastic
          2021-06-21 16:37:12.396Z

          When I push Fn+F8 in TinyPilot, the JavaScript key translation for this combination is MediaStop and TinyPilot won't send it (shows up in red). My keyboard can also be recognized by the laptop if I connect it directly. However, I believe this is moot because even though the laptop will let me use an external keyboard, that particular key command (Fn+F8) still doesn't work and will only be acknowledged if pressed on the laptop keyboard. There's a BIOS setting for locking the F-keys to always use their secondary function, but that setting isn't utilized during boot. Doesn't feel like an issue with TinyPilot, but more of a hardware limitation the more I look at it.

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          1. Michael Lynch @michael2021-06-21 19:42:41.465Z

            It could be a hardware limitation. Would you mind sharing your logs to see if there are any clues there?

            They're available under System > Logs > Get Shareable URL

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            1. H@hicktastic
                2021-06-21 21:05:23.333Z

                Here's the websocket chatter when I send Fn+F8 from another Dell laptop:

                4280["keystroke",{"metaKey":false,"altKey":false,"shiftKey":false,"ctrlKey":false,"altGraphKey":false,"sysrqKey":false,"key":"OS","code":"OSLeft"}]
                4380[{"success":true}]

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