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Author Topic: Some info about the HDMI output on the Gemini  (Read 6778 times)

Varti

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Some info about the HDMI output on the Gemini
« on: December 28, 2017, 12:00:05 pm »
Hi,

as it stands, the Gemini doesn't have a built-in HDMI connector. It is possible to have a HDMI output via the USB-C port, but only a custom cable provided by Planet Computers can be used. Some users (including myself) have been wondering why a connector hasn't been included in the device, and why generic USB-C-to-HDMI cables can't be used. In case any of you is wondering the same, the user simon5mx has done some research and published some interesting facts on the Indiegogo project's comments page (https://www.indiegogo.com/projects/gemini-p...22374#/comments):

- including a HDMI connector would have been too expensive due to licensing fees: "[the fee] for HDMI manufacturers making fewer than 10,000 units per year is an annual fee of $5,000 with a royalty rate of $1 per unit." Source: https://en.wikipedia.org/wiki/HDMI#Cost https://hdmi.org/manufacturer/terms.aspx

- the reason why generic USB-C-to-HDMI adapters can't be used: "The MT6797 (X20, X25/X27 same family) doesn’t include a built-in HDMI interface. The X20 Development Board deploys the built-in DPI interface as the source for the HDMI output. A peripheral Bridge IC (U6502, MT8193) performs this task. So if the motherboard doesn’t have a DSI-HDMI Bridge IC then I guess the adaptor cable will need to do it. Perhaps DSI outputs are chip specific and the bridge chip needs to be programmed accordingly; hence a standard usb-c to hdmi adaptor isn’t going to do it." Reference: https://github.com/96boards/documentation/b...reUserManual.md

This cable is available only in the Connectivity Pack, in the All In Upgrade pack and in the All In Bundle, and it cannot be ordered separately, though it has been commented by Planet that "Once Gemini officially launches to general retail the cables will be available individually. For now, and for simplicity, we wanted to keep all the cables as part of the Connectivity Kit".

Thanks to simon5mx for the research and to Planet Computers for the clarification.

Varti
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babcom5

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Some info about the HDMI output on the Gemini
« Reply #1 on: May 23, 2018, 10:27:27 am »
Hi,

I have the cable as part of the pack. But when I connect it to a hdmi cable and into a monitor I just get a blank screen on the d vice the configure hdmi is greyed out. Any ideas ?
« Last Edit: May 23, 2018, 10:37:01 am by Varti »
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Daniel W

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Some info about the HDMI output on the Gemini
« Reply #2 on: May 23, 2018, 06:06:56 pm »
Quote from: babcom5
Hi,

I have the cable as part of the pack. But when I connect it to a hdmi cable and into a monitor I just get a blank screen on the d vice the configure hdmi is greyed out. Any ideas ?

Just to make sure, are you using the USB-C port on the right hand side (same side as Enter)? Only that port supports the HDMI adapter.
If screencast is enabled (Settings > Display > Cast > (three dots) >
  • Enable wireless display), HDMI will turn off and vice versa.


I don't know if the sequence matters, but what I usually do, is to first plug the HDMI cable into the adaptor cable, then plug it into the Gemini. Then I go to Settings > Display > HDMI settings and turn on the toggle (far right end of the "HDMI" row). As soon as my (FHD) TV locks on to the signal, the video resolution option becomes available, but all I have even seen there is (o)Auto.

I do notice the Gemini sends out a 1080p signal at 60Hz. If possible, make sure you monitor is compatible with that. It probably is, but I have heard of some PAL TVs that only works with 50Hz. If you have access to some other device(s) that will accept an HDMI signal, even if it is the neighbours TV, it might be worth trying out, just to see if it works, in which case you'll at least know nothing is broken.
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DJO

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Some info about the HDMI output on the Gemini
« Reply #3 on: May 23, 2018, 06:43:53 pm »
Quote from: Varti
This cable is available only in the Connectivity Pack, in the All In Upgrade pack and in the All In Bundle, and it cannot be ordered separately

Not so, the cable is available separately direct from PC

I don't know if they have stock now but I ordered one last week, if it turns up soon I'll repost here.
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Calamityspice

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Some info about the HDMI output on the Gemini
« Reply #4 on: May 23, 2018, 08:37:26 pm »
I just cast to my PC. No cables required.
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Daniel W

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Some info about the HDMI output on the Gemini
« Reply #5 on: May 24, 2018, 07:08:52 pm »
Quote from: Calamityspice
I just cast to my PC. No cables required.
Indeed, though wireless casting typically it causes more lag than a HDMI cable.
In my experiments, HDMI gives me 100-120ms video lag and 150ms audio lag.
Miracast gives me about 380-400ms video lag and 300ms audio lag.
(Which means both are somewhat useless to me, but that's borderline OT.)
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