lewmur
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Problem with 3.5" screen resolution [solved]

Tue Dec 25, 2018 5:38 pm

I just bought a 3.5" touchscreen for my Pi 3B who's resolution is only 320 x 480 but the lowest res in Raspberry Pi Configuration is 640x 480. At this res a large portion of the screen is cut off. How can I set to lower res?

W. H. Heydt
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Re: Problem with 3.5" screen resolution

Tue Dec 25, 2018 5:56 pm

Check the setup instructions on the vendor's web site. I'd have to dig into one of mine to check how, but it is possible to tell the system that the screen is 480x320.

lewmur
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Re: Problem with 3.5" screen resolution

Tue Dec 25, 2018 6:17 pm

Bought from Newfrog in China. No website. :cry:

klricks
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Re: Problem with 3.5" screen resolution

Tue Dec 25, 2018 6:29 pm

Try enabling and configuring the framebuffer settings in /boot/config.txt
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.

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mahjongg
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Re: Problem with 3.5" screen resolution

Tue Dec 25, 2018 6:31 pm


lewmur
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Re: Problem with 3.5" screen resolution

Tue Dec 25, 2018 6:41 pm

mahjongg wrote:
Tue Dec 25, 2018 6:31 pm
viewtopic.php?f=28&t=5851
The lowest setting there is still 640x480.

lewmur
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Re: Problem with 3.5" screen resolution

Tue Dec 25, 2018 7:09 pm

klricks wrote:
Tue Dec 25, 2018 6:29 pm
Try enabling and configuring the framebuffer settings in /boot/config.txt
Uncommented framebuffer width and height in /boot/config.txt and set to 480 x 320 but when I rebooted, display hadn't changed.

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mahjongg
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Re: Problem with 3.5" screen resolution

Tue Dec 25, 2018 7:16 pm

Are you sure Your monitor uses HDMI ?
If so it should have an eprom with EDID data you can readout.

The RPI is able to generate lower resolutions, for example for generating PAL and NTSC resolutions

lewmur
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Re: Problem with 3.5" screen resolution

Tue Dec 25, 2018 7:26 pm

mahjongg wrote:
Tue Dec 25, 2018 7:16 pm
Are you sure Your monitor uses HDMI ?
If so it should have an eprom with EDID data you can readout.

The RPI is able to generate lower resolutions, for example for generating PAL and NTSC resolutions
Who said anything about an HDMI monitor? I'm trying to set up a 3.5" LCD screen plugged into the GPIO pins.

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Re: Problem with 3.5" screen resolution

Tue Dec 25, 2018 7:32 pm

lewmur wrote:
Tue Dec 25, 2018 7:26 pm
mahjongg wrote:
Tue Dec 25, 2018 7:16 pm
Are you sure Your monitor uses HDMI ?
If so it should have an eprom with EDID data you can readout.

The RPI is able to generate lower resolutions, for example for generating PAL and NTSC resolutions
Who said anything about an HDMI monitor? I'm trying to set up a 3.5" LCD screen plugged into the GPIO pins.

In your initial post you never stated GPIO, could you post pictures of product ??
Retired disgracefully.....

klricks
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Re: Problem with 3.5" screen resolution

Tue Dec 25, 2018 7:52 pm

Is this it? https://www.newfrog.com/product/3.5-inc ... -2b-250175

The config settings are for HDMI only.

You might want to do some Google search of this forum. There are many posts concerning 3.5" screens.

From what I remember the small screens are good for custom GUI interfaces but almost unusable for general OS desktop usage.
Even if you could get the resolution right, many programs use hard coded screen size and/or menus that will go off the screen and are impossible to navigate.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.

lewmur
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Re: Problem with 3.5" screen resolution

Tue Dec 25, 2018 8:44 pm

klricks wrote:
Tue Dec 25, 2018 7:52 pm
Is this it? https://www.newfrog.com/product/3.5-inc ... -2b-250175

The config settings are for HDMI only.

You might want to do some Google search of this forum. There are many posts concerning 3.5" screens.

From what I remember the small screens are good for custom GUI interfaces but almost unusable for general OS desktop usage.
Even if you could get the resolution right, many programs use hard coded screen size and/or menus that will go off the screen and are impossible to navigate.
Yes, that is it. I've tried the searching this forum but the problem with that is that there are too many hits with none of them seeming to be relevant. Actually, my Pi is used as an FTP server and webpage host, so I don't use it for browsing or running other apps. The main thing I want the screen for is setting up Synergy and Teamviewer when it first boots. In the past, I've had to disconnect either my Chromecast or Fire TV stick to use an HDMI port on my 40" monitor.

W. H. Heydt
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Re: Problem with 3.5" screen resolution

Tue Dec 25, 2018 8:49 pm

Okay... Now that I have a little time...

Lesson 1: Never buy equipment from a company that doesn't provide adequate support. For Pi accessories, no website is a strong indicator that there is no support.

Here are the relevant setting for the Neosec 3.5" GPIO mounted display that I use (YMMV):

Code: Select all

[email protected]:~ $ cat /boot/cmdline.txt
dwc_otg.lpm_enable=0 console=serial0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait modules-load=dwc2,g_ether fbcon=map:10 fbcon=font:VGA8x8 consoleblank=0
For config.txt, I'm only going to include the relevant parts...

Code: Select all

[email protected]:~ $ cat /boot/config.txt

# uncomment this if your display has a black border of unused pixels visible
# and your display can output without overscan
disable_overscan=1

# Overlay for TinyLCD35 (Neosec)
dtoverlay=tinylcd35,rotate=270,speed=48000000,touch
No idea if those settings will work for your display, but they work for mine. At least it should point you in the *general* direction to do what you're looking for.

lewmur
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Re: Problem with 3.5" screen resolution

Tue Dec 25, 2018 9:08 pm

W. H. Heydt wrote:
Tue Dec 25, 2018 8:49 pm
Okay... Now that I have a little time...

Lesson 1: Never buy equipment from a company that doesn't provide adequate support. For Pi accessories, no website is a strong indicator that there is no support.

I've been in the game of building my own computers since 1978 and that is hardly lesson number one. :D :D I'd certainly never buy anything of importance from a Chinese supplier, but taking a chance on something that cost only $16, to scratch an itch that has been bothering me for sometime, is a chance I'm quite willing to take. ;)

W. H. Heydt
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Location: Vallejo, CA (US)

Re: Problem with 3.5" screen resolution

Wed Dec 26, 2018 1:11 am

lewmur wrote:
Tue Dec 25, 2018 9:08 pm
W. H. Heydt wrote:
Tue Dec 25, 2018 8:49 pm
Okay... Now that I have a little time...

Lesson 1: Never buy equipment from a company that doesn't provide adequate support. For Pi accessories, no website is a strong indicator that there is no support.

I've been in the game of building my own computers since 1978 and that is hardly lesson number one. :D :D I'd certainly never buy anything of importance from a Chinese supplier, but taking a chance on something that cost only $16, to scratch an itch that has been bothering me for sometime, is a chance I'm quite willing to take. ;)
Have it your way. You appear to have purchased a not terribly expensive paperweight.

lewmur
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Re: Problem with 3.5" screen resolution

Wed Dec 26, 2018 1:12 pm

W. H. Heydt wrote:
Wed Dec 26, 2018 1:11 am
lewmur wrote:
Tue Dec 25, 2018 9:08 pm
W. H. Heydt wrote:
Tue Dec 25, 2018 8:49 pm
Okay... Now that I have a little time...

Lesson 1: Never buy equipment from a company that doesn't provide adequate support. For Pi accessories, no website is a strong indicator that there is no support.

I've been in the game of building my own computers since 1978 and that is hardly lesson number one. :D :D I'd certainly never buy anything of importance from a Chinese supplier, but taking a chance on something that cost only $16, to scratch an itch that has been bothering me for sometime, is a chance I'm quite willing to take. ;)
Have it your way. You appear to have purchased a not terribly expensive paperweight.
Too light to be a paper weight. I prefer to think of it as an inexpensive puzzle. :lol:

lewmur
Posts: 371
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Re: Problem with 3.5" screen resolution

Thu Dec 27, 2018 4:17 pm

lewmur wrote:
Wed Dec 26, 2018 1:12 pm
W. H. Heydt wrote:
Wed Dec 26, 2018 1:11 am
lewmur wrote:
Tue Dec 25, 2018 9:08 pm


I've been in the game of building my own computers since 1978 and that is hardly lesson number one. :D :D I'd certainly never buy anything of importance from a Chinese supplier, but taking a chance on something that cost only $16, to scratch an itch that has been bothering me for sometime, is a chance I'm quite willing to take. ;)
Have it your way. You appear to have purchased a not terribly expensive paperweight.
Too light to be a paper weight. I prefer to think of it as an inexpensive puzzle. :lol:

Puzzle solved. 8-) Turns the Adafruit setup for their 3.5", works. This is probably a clone of their 3.5" Touchscreen for the Pi so Newfrog can't include the setup files.

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