How to setup 3.5 inch screen

[Yaszuthemage]

Hi there! I have been working on a project with a 3.5 inch waveshare display, I have been having issues, how would I setup a 3.5 inch waveshare screen to work on the Pi 4? I have been using Pi 3 config but It has not been running emulation station at all.

[mitu]

Which model is that ? There's no 'one-size-fits-all' configuration that can be applied.
Waveshare have instructions for installation of their displays in their Wiki, did you try to use them ?

[Yaszuthemage]

@mitu its the waveshare 3.5 inch rpi display 480x320 ive tried the configuration and installation but it didnt work with emulation station all it shows is a command line.

[mitu]

Add to your config.txt file (don't remove anything else, just add at the end):

hdmi_force_hotplug=1
dtparam=i2c_arm=on
dtparam=spi=on
enable_uart=1
dtoverlay=tft35a:rotate=90

See if, after boot, the display works.
NB: this assumes you're starting with a RetroPie image (from https://retropie.org.uk/download).

[Yaszuthemage]

@mitu It didnt work it just booted up like usual. I got retropie image from the raspi imager presets should I go to the image from that website?

[mitu]

It didnt work it just booted up like usual.

I got retropie image from the raspi imager presets should I go to the image from that website?

No, it's the same image - it doesn't matter how it's installed.

Unfortunately I don't know much about the various 3.5' models for Waveshare's displays - the above config was taken from one of their images, but it looks like there's more than 1 model with this resolution (and supported with different drivers).

I suggest looking at their Wiki page and try one of their images to see which one works (and then replicating the config.txt from the image onto the RetroPie installation) or trying their install script from https://github.com/waveshare/LCD-show/.