7 inch WaveShare RGB LCD HAT for Raspberry Pi CM4

Nexwell

Following our phone conversation, I'm starting a thread on the forum. The problem concerns Android version 14 and higher. I need to get my device running with the "7-inch WaveShare RGB LCD HAT for Raspberry Pi CM4" display working. A year ago, I was using Android version 13 on this device, and after making the appropriate changes to the /boot/config.txt file, the display worked without any problems. Now, on Android version 14, after making the same changes to the same file, the display is "dead." The entries we added to this file in Android 13 are:

dtoverlay=vc4-kms-v3d
dtoverlay=vc4-kms-DPI-7inch
dtoverlay=waveshare-7dpi

After the changes, the file looked like this (/boot/config.txt):

# This file is generated and maintained by emteria
# Please do not modify it manually, as your changes will be overwritten during the next OS update
# If you need to add or overwrite something, please add your changes to config-overrides.txt file

# audio
dtparam=audio=on

# Following definitions only apply when booted on Compute Module 4
[cm4]
dtoverlay=dwc2,dr_mode=host
dtoverlay=vc4-kms-v3d
dtoverlay=vc4-kms-DPI-7inch
dtoverlay=waveshare-7dpi

# Following definitions always apply to all devices
[all]
kernel=u-boot.bin
arm_64bit=1

# audio
hdmi_force_edid_audio=1

# disable kms audio path and force bcm2835 card  0 = hdmi card 1 = headphone jack
dtoverlay=vc4-kms-v3d,cma-384
dtoverlay=cma,cma-384
dtoverlay=rpivid-v4l2
disable_overscan=1

# add support for official 7" touchscreen
dtoverlay=rpi-backlight
display_auto_detect=1
dtoverlay=vc4-kms-v3d
dtoverlay=vc4-kms-DPI-7inch
dtoverlay=waveshare-7dpi

# add overlay for camera sensor and use firmware with codecs
dtoverlay=imx219
camera_auto_detect=1
start_x=1

# temporarily increase the CPU frequency on boot
initial_turbo=60

# enable serial console and pin core clock fixed to 500MHz
enable_uart=1

# load user-defined overrides for this config
include config-overrides.txt

Thank you in advance for any help.

IKS

Hi @Nexwell. Let's break it down into different parts and solve step by step. First, we need to make sure you have a working version on your side - doesn't matter which version. Since you already know that Android 13 was working fine, I will try to find that release in our archive and send it to you.

IKS

I found our release for CM4IO version 13.1.0 in our legacy installer. This is the same image you used, but in a different package format. You need to install it through our installer application right away.

First, please open our Downloads page and pick an installer for your OS:

Second, login into the installer and pick the correct device and version:

Here are some knowledge base articles to help you:

Please let me know if you can successfully boot the device with Android 13 by using your screen. If yes, we can continue with the next step of making it work on Android 16 or 17.

Nexwell

Thank you for your time and help but today we have succesfully managed to run your newest (newest available on RPi Imager tool) Android 16 for CM4 with applied 7" RGB LCD HAT configuration and it now works. It turns out that one of the *.dtbo files in overlay directory on your Android 14 and newer versions was missing. Additional statements in config.txt file were related to it, so we copied that file from /boot/overlay directory from our Android 13 backup and it helped.

IKS

@Nexwell thanks for the update. I am happy to hear it works on Android 16 too. Could you please tell us which dtbo file was missing (exactly)? We need to research why it is missing - otherwise it will disappear on the next OS update, because the boot partition is fully overwritten.

Nexwell

The file name is "waveshare-7dpi.dtbo" and it was present on Android 13 /boot/overlay directory but on Android 14, 15 and 16 its missing (and the value in "dtoverlay=" refers to the name of this file).

vrbinc

@Nexwell starting 16.0.3 nightly build for cm4io includes the necessary overlays. Please feel free to test.

Claus

I am wondering How get you access to the config.txt . When I open it, I got the message that only readable.
so how did you got root access?

vrbinc

@Claus please check out this article https://emteria.com/kb/edit-config-file

Claus

@vrbinc: thanks solved: Now I like to change the Display to an 7" with 800x600 resolution HDMI.
I saw that i can change on EMTERIA to autodetection, Firmware setting and Kernel settings.
Autodetection does not work.
in my understanding there is a Memory on the HDMI Display board reading out the posible settings automatically...

If I selecting the Firmware setting I use to change the settings on config-overrides.txt as follows:

config_hdmi_boost=4

#remove black borders
disable_overscan=1

#set specific CVT mode
hdmi_cvt 800 480 60 6 0 0 0

#set CVT as default
hdmi_group=2
hdmi_mode=87

i am able to see the booting lines on the display but after change to the emteria symbol entry grafic the display goes black and then I see only stribes on my display...

same thing when I change the settings on emteria to kernel the I have the same result. After setting the video=HDMI-A-1:800x480M@60 in the file cmdline.txt.

where is my error?

other point: when I set the settings in emteria to autodetection for display and delete all settings on config-override or cmdline files. I expecting that the Emternia is detecting my reglual Monitor with a standard resolution 1k something but is goes back to fw ore kernel setting to the 640x480 resolution.

thats strange...
Maybe I have to post it ot an other thread ?

regards Claus

Claus

just share my information:
I have found a solution to switch to 800x480.

With following steps:

change settings in Android17 (Emteria,Raspberry PI4) in the menu System -Rasberry Requested Resolution to 800x480@60
Force specific display configuration to Force firmware mode setting
shut down
change in the config.txt as follows:

add the line to the end of the file

max_usb_current=1
hdmi_force_hotplug=1
config_hdmi_boost=7
hdmi_group=2
hdmi_mode=87
hdmi_drive=1
hdmi_cvt 800 480 60 6 0 0 0

delete the line or comment the line

display_auto_detect=1

and thats it...
regards
Claus

vrbinc

@Claus happy to hear you resolved the issue

Nexwell

I confirm that even 16.3.0 (which i suppose includes this fix) also works with this touchscreen on our devices. Therefore we can assume that issuse is fixed now.