Setting the Screen Resolution

HDMI monitors normally transmit what is called the EDID data when the RevPi Flat is started. This data includes, among other things, the possible resolutions that the monitor supports and a preferred resolution that is then selected by the system.

If the monitor is not turned on or connected at startup, however, this data will not be available. It is possible that the resolution is then incorrect or in the worst case that the monitor remains black.

This also applies to monitors that do not transmit EDID data or transmit incorrect EDID data. In all these cases you should set the resolution manually.

We will now use this example to fix this problem together.

You require:

  • RevPi Flat
  • Your PC
  • Power supply unit for the power supply
  • Ethernet cable if you do not use WLAN

Let’s go!

  • Determine the current settings for the resolution with the following command:


You see the current settings:


There are two operating modes for screens:

– Group 1: CEA (typical setting for TV monitors)

– Group 2: DMT (typical setting for PC monitors)

  • Enter the following command if you are using a TV: “/opt/vc/bin/tvservice -m CEA” or
  • Enter the following command if you are using a PC monitor: “opt/vc/bin/tvservice -m DMT”

All possible resolutions are displayed:


Make a note of the “mode” you want to use.

You can set the resolution for your monitor in the “config.txt” configuration file.

  • Launch the text editor to edit the file:


  • Change the following values: – HDMI Mode – HDMI Group (1 for TV, 2 for PC monitor)
  • Remove the # character before the lines you have changed. # disables the functions.

To ensure that an image is also displayed completely on a CRT TV, the RevPi Flat has the “Overscan” function.

If you are using a modern screen, this function may cause distracting borders to appear on the screen.


  • Launch the text editor to edit the file:


  • Remove # before the entry “disable_overscan=1”.
  • Save the file.
  • Restart your RevPi Flat: “sudo shutdown – r 0”.

The screen resolution is changed with the restart.