By default, the HDMI output of the Raspberry Pi is only activated if a monitor or a TV is connected and powered up before the Raspberry Pi is started up.
Fortunately, there is an easy fix which will force the Raspberry Pi to turn on the HDMI output, no matter whether a display is connected or not.
In this note i will show how to force the HDMI output on the Raspberry Pi by modifying the HDMI hotplug settings.
Force HDMI Hotplug on Raspberry Pi
To force the Raspberry Pi to turn on the HDMI output, it is required to uncomment some setting in the
$ sudo nano /boot/config.txt
1 to activate the HDMI output, even if no monitor is detected:
To configure the HDMI output format, check the list of HDMI groups and modes here and set the appropriate numbers:
For example, set
1 if the Raspberry Pi is connected to a TV and
16 to select the resolution
60Hz and the screen aspect
Enable the HDMI sound output:
After updating the
/boot/config.txt file, reboot the Raspberry Pi to apply the changes.