Hikey 960 Compatible LCD touchscreen list


#1

Dear fellow hikey 960 users, I want to add a touchscreen LCD display to my hikey 960. Is there a definitive list of LCD displays known to work with it?

I found this blog post: https://www.96boards.org/blog/linksprite-hikey-aosp/
which from a quick google search points to this product: https://www.arrow.com/en/products/96boards-display-7/linksprite-technologies-inc

I am hopefully trying to find a larger screen with a higher resolution. Hoping that someone here in the community would have a better idea.


#2

Most should work.

I’ve personally tested with this;
https://www.chalk-elec.com/?page_id=1280#!/7-open-frame-universal-HDMI-LCD-with-capacitive-multi-touch/p/21750207/category=3094861
(they have other sizes as well, probably all work)

and with this;
https://www.aliexpress.com/item/CARPC-Kit-7-Inch-1024-600-LCD-High-Brightness-Dirver-Board-Capacitive-Touch-Screen-HDMI-VGA/32251750075.html

One thing to be aware of is that USB POWERED displays probably won’t work unless you supply power externally. This is because there is no working hotplug support, and the USB power isn’t applied until too late.


#3

Thank you @doitright, are you using this with AOSP?

Follow up question - As I continue my search, I am looking at screen such as this: https://www.amazon.com/Raspberry-10-1-Display-Touchscreen-SunFounder/dp/B0776VNW9C
This screen claims android support - since Im new to the AOSP world, in your experience does this translate to - it will work with AOSP as well?


#4

“Android” doesn’t doesn’t have any relevance when it comes to display support.

The display negotiates its settings with the kernel by sending it a packet of data called an EDID. The kernel checks this EDID and if it is able to provide a display mode compatible with the monitor, then the monitor comes alive. This all happens BEFORE Android starts up.

Similarly, the touchscreen digitizer is also something between the hardware and the kernel. Virtually ALL USB touchscreen digitizers now work with Linux.

The biggest stumbling block that you can come across in picking a display for these units is in the clock generator on the board’s SoC. It is not quite able to reproduce the timings necessary for standard HDMI modes. Monitors that are extremely rigid about the modes they accept may refuse to light up. But again, this has absolutely nothing to do with Android, rather it is a hardware limitation.

I’d be willing to wager $50 that the monitor you link to WILL work on this board. Reason being that I can see in the pictures of the display controller board, that it is a realtek chip, which is a particularly common chip used in small displays (its the same chip used in the second of the two monitors I linked to), and they all run variations on the same software.


#5

Thank you @doitright - that was a really nice explanation.

I shouldve mentioned why I brought up Android support - it was more geared towards touchscreen support. From the blog post I linked earlier, It seemed that the Linksprite board did not have touchscreen support until it was incoroporated into a later build.

This is what was said:

But till now the Hikey boards, specially the HiKey960, were incompatible with this display. Which meant that if someone wanted to do a project using Android and 96Boards, their best bet was to use either of the Hikey boards. But then they weren’t able to use the Linksprite display as it was not compatible.
It Works Now!
However, with help from John Stultz, we were recently able to get this display working. And has been upstreamed to the AOSP kernel (https://android-review.googlesource.com/#/c/kernel/hikey-linaro/+/505547/).
So now, with an updated AOSP build, the Linksprite display should work out of the box!