Monitors that work with Dragonboard 401c


#1

I know this has been asked before but I can’t seem to find a clear answer. I think that the LinkSprite 7" monitor at $90 will work with some Linux distro’s but not sure if it will work with Android as well.

There are many monitors available for Raspberry PI starting around $30 but I wouldn’t know which model might work on Dragonboard 410c in Linux and/or Android.

Any guidance greatly appreciated,
Carl


#2

I would say that HDMI + USB combo is an easier setup, I’ve personally used a GIANTEC 11.6" MONITOR 1080p (HDMI) + touchscreen (USB), but maybe it’s too large for your use-case.

You can also find some feedbacks here:


#3

HI Carl

Your research is about right. The graphics stacks for Debian and Android are hugely different and the stack we use of Debian benefits from reusing all the code in the Linux kernel to support different PC monitors.

The Debian builds are able capable of driving most monitors and will automatically adopt the best display resolution (providing the display correctly reports its EDID). There are a few hicoughs every now and then but you can be fairly confident that a monitor will “just work” with Debian.

Android is more difficult. Technically speaking it can be configured for different video modes but it is a complex task. Qualcomm published an application note on the subject: https://developer.qualcomm.com/qfile/28816/lm80-p0436-4_dsi_display_porting_guide.pdf . The material is technically demanding (and relies on you realising the HDMI on DB410C is implemented as a DSI to HDMI bridge).


#4

Thank you @danielt and @Loic I have the hdmi and an additional 5v usb port available for power and this will probably work with a Raspberry PI like designed monitor which I can get from Amazon ~$35 and return if it does not work out. I realize that this will likely work with Linaro but will only display on about 1/4 of the screen for ubuntu but that is good enough for experiments. What I don’t understand (and the explanation is likely over my head) is why this works( lol ) flawlessly on my $250 50" lcd TV for both Linaro and for Android and not very well on these small lcd monitors. Perhaps it is the touch screen aspect (which I don’t really need) that complicates things.
Thanks again.


#5

Ubuntu Core should in principle be similar to our Debian releases.

Ubuntu Core is a third party release so if it doesn’t work you have to tell them rather than us. Having said that we talk to the guys who make this stuff (its on the OpenHours archive and we know that both systems are based on the fully open source freedreno mesa/drm drivers. In other words if it works in Linaro Debian releases but not in Ubuntu Core then consider pinging the Ubuntu guys… they may be keen to fix it!


#6

Did you possibly mean Android core is a third party release (maybe Android is based on Ubuntu core - not sure). Anyway Linaro is fine - I don’t need Ubuntu but it would be nice if it worked properly on Android so probably it is Android (Google) that I need check with why the Android image only works on my 50" hdmi TV but not on a 5" hdmi screen that is powered by 5V DC. I know you are trying your best to be helpful and maybe it is my lack of understanding - especially about the Android image - that is the reason I don’t fully grasp the problem. It is after all a hobbiest board and people like myself using it need to be more knowledgeable than an average consumer of electronic devices.


#7

I did find a GIANTEC 11.6" MONITOR on ebay for about $45. Did you try this with the Android image and if so did it work as expected (e.g. no 1/4 of the screen issue)?


#8

No… I meant Ubuntu Core (this is another OS available for DB410C in addition to the Debian images from Linaro and the AOSP build from Qualcomm.

However, whilst I meant what I said I think perhaps I didn’t properly read your post first time round.

This was the bit that confused me: I couldn’t understand why Debian would be sized correctly but Ubuntu would not. However I now guess that this was a misinterpretation.


#9

Sorry - I worded it wrong should have stated it more like:
I realize that this will likely work fine with Linaro, but for Android it will only display on about 1/4 of the screen.


#10

For the cheaper end of displays I think even getting a quarter screen would be somewhat lucky. Not displaying anything is perhaps more likely. As you go up the prices slightly you will find monitors with downscalers (so they can display 1920x1080p60 even the panel resolution is less than this). I’m afraid I haven’t bought one of these yet (though I’ve been looking) so haven’t got a concrete recommendation for you.