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Newbie needs help with Waveshare HDMI LCD screen+TB
#1
Hi everyone!
I'm a total newbie when it comes to Linux-based systems, Tinker Boards and the likes... but I decided to start a project that requires me to connect my Tinker Board to a 4 inch screen. 
So I bought the Waveshare 4inch HDMI LCD screen - but unfortunately I can't get it to work!
All I get is a black screen.. sometimes a blue one that fades slowly to black.

I never got to see any text showing or anything at all on the LCD screen except when I connected my Google Chromecast to it - and even then the picture was not clear at.

So I'm thinking this is probably an overscan or resolution issue. I managed to change my Tinkerboard resolution to match the one required by the LCD screen (800x480).

I've spent a few days trying to get this thing to work, read all tutorials and posts on several forums, and I've ran out of ideas. Most tutorials are for the Raspberry Pi and they refer files that I can't seem to find (like the config.txt). There are some overlays and drivers and stuff out there for the Pi but I can't find the equivalent locations on the Tinker Board.

Does anyone know what may be causing this?
Can someone please help me out?  Sad

Thank you!
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#2
(05-14-2018, 02:21 AM)vila4480 Wrote: Hi everyone!
I'm a total newbie when it comes to Linux-based systems, Tinker Boards and the likes... but I decided to start a project that requires me to connect my Tinker Board to a 4 inch screen. 
So I bought the Waveshare 4inch HDMI LCD screen - but unfortunately I can't get it to work!
All I get is a black screen.. sometimes a blue one that fades slowly to black.

I never got to see any text showing or anything at all on the LCD screen except when I connected my Google Chromecast to it - and even then the picture was not clear at.

So I'm thinking this is probably an overscan or resolution issue. I managed to change my Tinkerboard resolution to match the one required by the LCD screen (800x480).

I've spent a few days trying to get this thing to work, read all tutorials and posts on several forums, and I've ran out of ideas. Most tutorials are for the Raspberry Pi and they refer files that I can't seem to find (like the config.txt). There are some overlays and drivers and stuff out there for the Pi but I can't find the equivalent locations on the Tinker Board.

Does anyone know what may be causing this?
Can someone please help me out?  Sad

Thank you!

Hi, you can take a try with this.
https://tinkerboarding.co.uk/wiki/index.php?title=3.5/4_inch_HDMI_LCD
Reply
#3
(05-14-2018, 09:38 AM)Tinker Board Wrote: Hi, you can take a try with this.
https://tinkerboarding.co.uk/wiki/index.php?title=3.5/4_inch_HDMI_LCD

Thank you for your reply!
I did try to follow that tutorial closely as it seems like it fits the screen I've got.
However being a newbie, some steps are very unclear to me!

1:
Code:
# Add the dts overlay for Ads7846 touch IC
$ cp ads7846-tinker-overlay.dts {codebase}/kernel/arch/arm/boot/dts/overlays
$ cp Makefile {codebase}/kernel/arch/arm/boot/dts/overlays

I wasn't sure what {codebase} referred to... but I couldn't find any folders for kernel or arch or arm at all! So I put my files into the base folder /boot/dts/overlays. Did I do that right? Tongue

2:
Then comes this part:
Code:
Then add the line into the end of miniarm-rk3288_defconfig:
# The file in {codebase}/kernel/arch/arm/configs/miniarm-rk3288_defconfig
$ CONFIG_TOUCHSCREEN_ADS7846=y

The only miniarm file I could find was named "miniarm-rk3288" which I believe was a .dtb (or dts?) file which is uneditable. I found a way to convert it to dts.. the instructions made very little sense to me at that point and after making some changes I was unable to convert back to .dtb due to various errors related to the code structure (I only added the one line at the bottom of the last section... didn't seem to fit well into it though!).

3:
Code:
 To modify kernel is done, please re-build your image and flash for next step.
Sorry I got no idea what it means to rebuild an image or flash... I searched everywhere for info on how to do that or what it meant...  Confused  i feel dumb..

4: 
From what I understood those previous changes only affect the touchscreen. However I was unable to get the screen to work at all. All I get is a blue screen that fades slowly to black.
Also, the following instruction refers to a file that does not exist in the attached files. The file I've got doesn't include "-tinker" in its filename:
Code:
After reboot your device, modify /boot/hw_intf.conf to load the dts overlay we just added:
intf:dtoverlay=ads7846-tinker
Other than that I believe that I have done every other step correctly.

Sorry for taking your time but I really can't figure this one out by myself and I have no clue as to what I'm doing wrong...!!
If I manage to figure this one out I'll post a video on youtube for others who might be facing the same issue I am.
I'm using the latest version of TinkerOS.

Thank you,
-ViLa4480
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#4
(05-15-2018, 12:18 PM)vila4480 Wrote: 1:
Code:
# Add the dts overlay for Ads7846 touch IC
$ cp ads7846-tinker-overlay.dts {codebase}/kernel/arch/arm/boot/dts/overlays
$ cp Makefile {codebase}/kernel/arch/arm/boot/dts/overlays

I wasn't sure what {codebase} referred to... but I couldn't find any folders for kernel or arch or arm at all! So I put my files into the base folder /boot/dts/overlays. Did I do that right? Tongue

This {codebase} mean the kernel source code.
And you can find our source code here, https://github.com/TinkerBoard/debian_kernel

(05-15-2018, 12:18 PM)vila4480 Wrote: 2:
Then comes this part:
Code:
Then add the line into the end of miniarm-rk3288_defconfig:
# The file in {codebase}/kernel/arch/arm/configs/miniarm-rk3288_defconfig
$ CONFIG_TOUCHSCREEN_ADS7846=y

The only miniarm file I could find was named "miniarm-rk3288" which I believe was a .dtb (or dts?) file which is uneditable. I found a way to convert it to dts.. the instructions made very little sense to me at that point and after making some changes I was unable to convert back to .dtb due to various errors related to the code structure (I only added the one line at the bottom of the last section... didn't seem to fit well into it though!).

As the item 1, that is one of file in the kernel source code.
https://github.com/TinkerBoard/debian_kernel/blob/release/arch/arm/configs/miniarm-rk3288_defconfig

(05-15-2018, 12:18 PM)vila4480 Wrote: 3:
Code:
 To modify kernel is done, please re-build your image and flash for next step.
Sorry I got no idea what it means to rebuild an image or flash... I searched everywhere for info on how to do that or what it meant...  Confused  i feel dumb..

You can refer to this https://tinkerboarding.co.uk/wiki/index.php?title=Software#Kernel, to step by step re-build the kernel.
Then you can get new kernel with new config, and have the ads7846-tinker.dtb file.

Please take a try, and let us know if any the problem.

Thanks.
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#5
Hi, vila4480
    We have committed the change to the github, so you can use the following step instead of step a.
    step 1 :
    https://tinkerboarding.co.uk/wiki/index.php?title=Software#Kernel
    And after Get source code: before Building image:, please apply the following patch
  https://github.com/TinkerBoard/debian_kernel/commit/58dc6ada2b7991c7ca5f7bcceb839ee5bb123212

  step 2
  After finish the above SOP, just follow the step b of the below SOP to finish the setup
  https://tinkerboarding.co.uk/wiki/index.php?title=3.5/4_inch_HDMI_LCD
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#6
Wow amazing support thank you.
I'll try to follow your tips and I'll come back to share the results!

Thanks guys!
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