For my experiments with RetroPie I have bought a 480x320 pixels 3.5 inch HDMI screen on AliExpress. By default the configuration was to show on a Full HD (1920x1080) monitor. When connected to the tiny screen it was downscaling making the whole screen blurry.

Note that this probably works on any RaspberryPi with a Raspbian distribution.

In order to have a 1:1 ratio on the screen we have to set our resolution in /boot/config.txt.To edit, exit emulationstation (Select > Quit > Quit EmulationStation), then type sudo nano /boot/config.txt.

  • Remove the # before hdmi_force_hotplug=1.
  • Remove the # before hdmi_group and set it to 2.
  • Remove the # before hdmi_mode and set it to 87. This is the custom HDMI mode, so now we have to set a custom resolution and refresh rate:
  • Add hdmi_cvt=480 320 60 (or set it to your resolution and refresh rate).
  • Reboot.
  • Profit.

Here are all the lines as I have them in a snippet:

hdmi_cvt=480 320 60