Matthai
Posts: 11
Joined: Thu Jan 14, 2016 3:59 pm

KeDei 3.5 inch SPI TFT LCD (version 6.1)

Wed Jun 01, 2016 8:56 am

Hi,

I have bought 3.5" LCD TFT Touch Screen Display for Raspberry Pi 3 fo around 12 USD.

When it came, it turs out it is from a company KeDei. It is marked:
KeDei
3.5 inch SPI TFT LCD,
480x320 16bit/18 bit
ver 6.1 2016/5/1
I am using it on Raspberry Pi version 3, OS is Raspbian 8.0 and system is fully updated:
- firmware is from May 31 2016 11:48:49 (version 6faf136a2445687e1bd90c8c763a8796ace73be2 (clean) (release))
- kernel is: Linux rpi3 4.4.11-v7+ #891 SMP Tue May 31 12:30:26 BST 2016 armv7l GNU/Linux

The problem is, that the producer claims this display is working only with their "special" version of Raspbian (they are providing an image). And there in almost zero documentation (the display came without any documentation).

However, Googling around I have found that some people were able to compile and install kernel drivers and it seems that some drivers are available from here: http://kedei.net/raspberry/raspberry.html

I downloaded and untar-ed drivers for my version of device (6.1):

Code: Select all

wget http://kedei.net/raspberry/v6_1/LCD_show_v6_1.tar.gz
tar zxvf LCD_show_v6_1.tar.gz
Then I tried to run the binary:

Code: Select all

cd LCD_show_v6_1/
./LCD35_v
Now what happens... main HDMI screen cets coloured in four colors (red-yellow-blue-cyan), but SPI display started working. It shown four raspberry logos and a bunch of text, which ends with this line:
Waiting for root device /dev/mmcblk0p2...
SSH connection dies (I was running this commands via SSH), and after hard reboot, the same happens. So basically device in "bricked".

Any idea how to solve this problem? I also tried to connect a keyboard and a mouse, but the system is completely unresponsible...

MikeDK
Posts: 81
Joined: Thu Mar 19, 2015 12:01 pm

Re: KeDei 3.5 inch SPI TFT LCD (version 6.1)

Wed Jun 01, 2016 9:10 am

There is already a big thread about these kind of displays...:

viewtopic.php?f=44&t=124961

I did not read the full thread, but it seems the thread owner did some hardware/software hacking to get it working

I also have one of these displays ("vision 1.0" ... damn they could not even spell version right in their first try), and I once tried the full image given by kedei ... it worked, but I was very sceptical, and finally I worked on some other projects.

I found the thread I posted in the beginning yesterday... and one post is very interesting
viewtopic.php?p=960012#p960012

so there are "some strange connections to servers in china" when using the supplied driver !!!

If I were you, I would save all important data from your sdcard, and reinstall a fresh image.

Chances are high that you have already some malware on your sdcard!


regards,
MikeDK

Matthai
Posts: 11
Joined: Thu Jan 14, 2016 3:59 pm

Re: KeDei 3.5 inch SPI TFT LCD (version 6.1)

Wed Jun 01, 2016 9:58 am

Yes, that was also my concern - malware. I just don't trust these damn Chinese hackers... ;)

Any chance this will be supported in Rapbian by default some day?

MikeDK
Posts: 81
Joined: Thu Mar 19, 2015 12:01 pm

Re: KeDei 3.5 inch SPI TFT LCD (version 6.1)

Wed Jun 01, 2016 10:06 am

Matthai wrote:Yes, that was also my concern - malware. I just don't trust these damn Chinese hackers... ;)

Any chance this will be supported in Rapbian by default some day?
If kedei is not giving any open source driver, then someone has to reverse-engineer the whole thing and write an open source driver on his/their own ...

problem is that there is even not any document describing what kind of controller is used on which board version, or how the interface works in detail ... just nothing!

they really force users to take their driver ... and get infected in the same step :evil:

sometimes it's better to pay more money for hardware, just to prevent frustration ;)

Matthai
Posts: 11
Joined: Thu Jan 14, 2016 3:59 pm

Re: KeDei 3.5 inch SPI TFT LCD (version 6.1)

Wed Jun 01, 2016 12:55 pm

Unfortunately, yes.

Do you have any suggestio which TFT screen to buy? Adafuit is very good, but quite expensive, especially delivery. Anything else?

MikeDK
Posts: 81
Joined: Thu Mar 19, 2015 12:01 pm

Re: KeDei 3.5 inch SPI TFT LCD (version 6.1)

Wed Jun 01, 2016 1:47 pm

I have exactly the same problem ... I bought that display because it was so cheap (5$ with free shipping - how is that even possible??)

Now I am frustrated about that display, and want something good ... but I can't decide which one to use ;)


MikeDK
Posts: 81
Joined: Thu Mar 19, 2015 12:01 pm

Re: KeDei 3.5 inch SPI TFT LCD (version 6.1)

Thu Jun 02, 2016 5:47 am

tinylcd wrote:hello

you can have a look at below 3.5 inch options

http://www.neosecsolutions.com//index.p ... d8d2a07712

http://www.neosecsolutions.com//index.php?cPath=20

regards
tinylcd
Hi and thanks ... the board looks promising .. but I can only see a whole image to download for this ... are there any hardware specs? open source drivers?

I'm sorry, but since i have tried that kedei display, I do not trust any periphal with no open documentation any more ... and my trust is even smaller when I'm only able to download a full image.

I want a display which works with well known drivers and the best would be, if there is already a devicetree overlay for that.

If all those cheap display manufacturers would just write open source drivers instead of providing some untrustful image, then many more ppl like me would buy them!


regards,
MikeDK

texy
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Forum Moderator
Posts: 5160
Joined: Sat Mar 03, 2012 10:59 am
Location: Berkshire, England

Re: KeDei 3.5 inch SPI TFT LCD (version 6.1)

Thu Jun 02, 2016 7:03 am

MikeDK wrote:
tinylcd wrote:hello

you can have a look at below 3.5 inch options

http://www.neosecsolutions.com//index.p ... d8d2a07712

http://www.neosecsolutions.com//index.php?cPath=20

regards
tinylcd
Hi and thanks ... the board looks promising .. but I can only see a whole image to download for this ... are there any hardware specs? open source drivers?

I'm sorry, but since i have tried that kedei display, I do not trust any periphal with no open documentation any more ... and my trust is even smaller when I'm only able to download a full image.

I want a display which works with well known drivers and the best would be, if there is already a devicetree overlay for that.

If all those cheap display manufacturers would just write open source drivers instead of providing some untrustful image, then many more ppl like me would buy them!


regards,
MikeDK
That's a very sensible approach - try and keep away from displays that need a custom OS in order to work. The tinylcd displays, at least the 3.5inch one anyway, have a fbtft overlay available by default in Raspbian - see for yourself in the /boot/overlays/ directory. You'll still need to do other configurations, like console redirection, etc.
Hope this helps,
Texy
Various male/female 40- and 26-way GPIO header for sale here ( IDEAL FOR YOUR PiZero ):
https://www.raspberrypi.org/forums/viewtopic.php?f=93&t=147682#p971555

Pilsener
Posts: 58
Joined: Thu Jan 03, 2013 3:25 pm

Re: KeDei 3.5 inch SPI TFT LCD (version 6.1)

Thu Jun 02, 2016 8:24 pm

I also get the "Waiting for root device /dev/mmcblk0p2" error.
It may be way off, but I noticed that the file /dev/mmcblk0p2 is missing from the installation that produces this error.

MikeDK
Posts: 81
Joined: Thu Mar 19, 2015 12:01 pm

Re: KeDei 3.5 inch SPI TFT LCD (version 6.1)

Fri Jun 03, 2016 8:11 am

Pilsener wrote:I also get the "Waiting for root device /dev/mmcblk0p2" error.
It may be way off, but I noticed that the file /dev/mmcblk0p2 is missing from the installation that produces this error.
Do you mean the file is not existing in the running system? or is it missing, when you look at the sdcard on another computer?
the files in directory /dev are not real files by means that they are somewhere on the harddisk (or sdcard).
Most of them are in fact device nodes, which are dynamically produced by the kernel and udev ... so you won't see them on the sdcard when you look at it on another computer.

/dev/mmcblk0p2 is in fact a device node to the second partition on the first mmc (sdcard) device in the system - which is the root partition on a raspbian (and probably also on other) system ... if this is not existing on a running linux, then there is no second partition and the boot process will never finish.

you can check on any other computer, if there are two partitions on the sd card ... if not, then either the image or the sdcard are messed up.

regards,
MikeDK

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