Waveshare 7.9 inch

Post Reply
fvolk
Posts: 740
Joined: Sun Jun 05, 2016 11:04 pm
languages_spoken: english
ODROIDs: C4, H2, H3
Has thanked: 0
Been thanked: 99 times
Contact:

Waveshare 7.9 inch

Post by fvolk »

Anyone have experience with the Waveshare 1280x400 7.9" screen?
https://www.waveshare.com/wiki/7.9inch_HDMI_LCD

Is this resolution with the C4 possible?
Any other practical insights?

User avatar
odroid
Site Admin
Posts: 40074
Joined: Fri Feb 22, 2013 11:14 pm
languages_spoken: English, Korean
ODROIDs: ODROID
Has thanked: 2841 times
Been thanked: 1602 times
Contact:

Re: Waveshare 7.9 inch

Post by odroid »

If you can use stock Kernel 4.9, you can try manually setting the HDMI configuration by modeline parsing.
https://wiki.odroid.com/common/applicat ... splay_mode
https://wiki.odroid.com/odroid-c2/appli ... utosetting

As far as I know, that display tweaking feature is not available in the mainline kernel.

fvolk
Posts: 740
Joined: Sun Jun 05, 2016 11:04 pm
languages_spoken: english
ODROIDs: C4, H2, H3
Has thanked: 0
Been thanked: 99 times
Contact:

Re: Waveshare 7.9 inch

Post by fvolk »

I usually prefer tobetter's 5.10 tree.
Hmm... I don't want to bet almost 100 EUR on this experiment for a status display attached to a C4.
I will continue my search...

joy
Posts: 1584
Joined: Fri Oct 02, 2015 1:44 pm
languages_spoken: english
ODROIDs: .
Has thanked: 179 times
Been thanked: 211 times
Contact:

Re: Waveshare 7.9 inch

Post by joy »

Hi @fvolk,

Let me check 1280x400 resolution based on the timing from this link.
https://www.waveshare.com/wiki/7.9inch_HDMI_LCD

Code: Select all

max_usb_current=1
hdmi_group=2
hdmi_mode=87
hdmi_timings=400 0 100 10 140 1280 10 20 20 2 0 0 0 60 0 43000000 3
And as @odroid mentioned, there is no HK's modeline parsing interface on mainline kernel (5.x)
but maybe edid firmware loading scheme with drm_kms_helper can be available.
Let me check it and then, if it's available, I will test 1280x400.

joy
Posts: 1584
Joined: Fri Oct 02, 2015 1:44 pm
languages_spoken: english
ODROIDs: .
Has thanked: 179 times
Been thanked: 211 times
Contact:

Re: Waveshare 7.9 inch

Post by joy »

@fvolk,

Based on the following data, the native resolution of waveshare 7.9 inch is 400x1280@50Hz.

Code: Select all

hdmi_timings=400 0 100 10 140 1280 10 20 20 2 0 0 0 60 0 43000000 3
Pixel clock is 43MHz, htotal 650, vtotal 1322 -> vsync 50Hz,
but I have no idea why the wiki page says refresh rate is 60Hz.
I tried to find more information, but no additional data for the monitor.
So I tested some under the assumption that it's 400x1280@50Hz.

Code: Select all

Detailed mode: Clock 43.000 MHz
                400  500  510  650 hborder 0
               1280 1285 1289 1322 vborder 0
               -hsync +vsync 
And actually, we don't have any monitor those native resolution is 400x1280@50hz,
just I found one monitor that shows ubuntu login display with 400x1280 size.

I've tested 400x1280@50Hz with two kernel versions of C4, (1) HK 4.9.y and (2) tobetter's 5.11.0.

(1) HK 4.9.y kernel
I got ubuntu mate login display on my monitor, 400x1280 size with the following option.

Code: Select all

display_autodetect=false
hdmimode=custombuilt
modeline="400,1280,43000,66153,50,400,500,510,650,1280,1300,1320,1322,0,1,1"
Theoretically, there is no problem to generate pixel clock 43MHz, width 400 and height 1280 with custombuilt logic,
but I'm not sure there is any specific factor on the Waveshare monitor to run on C4.

(2) tobetter's 5.11.0
I tried a test edid firmware but, I can't get any hdmi signal on my monitor.
I attached the test edid, 400x1280.bin.zip.

Code: Select all

$ cat /usr/share/flash-kernel/ubootenv.d/upstream/90-misc 
setenv bootargs "${bootargs} cma=800M"
setenv bootargs "${bootargs} clk_ignore_unused"

setenv bootargs "${bootargs} drm_kms_helper.edid_firmware=400x1280.bin"
# setenv bootargs "${bootargs} drm.edid_firmware=1920x1080.bin"
# setenv bootargs "${bootargs} drm.edid_firmware=1280x720.bin"
To confirm DRM KMS option, I've tried 1920x1080 and 1280x720 modes, and for those cases, I have normal HDMI display using the same drm.edid_firmware=${edid_name} in bootargs.
I think there may be additional work to be done in mainline 5.y kernel.

It looks complicated to find a good solution. :roll:
Attachments
400x1280.bin.zip
(271 Bytes) Downloaded 56 times

fvolk
Posts: 740
Joined: Sun Jun 05, 2016 11:04 pm
languages_spoken: english
ODROIDs: C4, H2, H3
Has thanked: 0
Been thanked: 99 times
Contact:

Re: Waveshare 7.9 inch

Post by fvolk »

Thank you joy for investigation!
So... may work or maybe not.
The other thing is that they can mount a RPi on the back, but that doesn't mean a C4 would also fit nicely.
Hmm...

fsckerdot1q
Posts: 2
Joined: Fri Jun 18, 2021 12:15 pm
languages_spoken: english
ODROIDs: C4
Has thanked: 0
Been thanked: 0
Contact:

Re: Waveshare 7.9 inch

Post by fsckerdot1q »

I have one of these monitors. On first power up everything worked fine. Now that I’ve erased my device I’m getting strange lines across the screen and it’s not actually readable. I’m using an odroid c4 with the android version that shipped on the emmc.

Post Reply

Return to “Hardware and peripherals”

Who is online

Users browsing this forum: No registered users and 2 guests