User avatar
DAve Shillito
Posts: 13
Joined: Sat Sep 08, 2012 1:15 pm
Location: Guildford

Connecting a DVI monitor via HDMI after boot.

Mon Apr 08, 2013 12:38 pm

Hi,

I'm not sure where this belongs as it not exactly a beginners question, but nor is it one for "power users" so here seems an appropriate place to ask.

I have a Pi set up using public/private key authentication for ssh access.

Unfortunately while adding an additional key I managed to mess up my .ssh/authorized_keys file preventing any login using ssh.

This was entirely my only stupid fault, and no real hassle as I just needed to connect up a monitor and keyboard to login and fix it.

However when I attached a monitor to the HDMI using a HDMI->DVI cable the monitor did not display anything, forcing me to turn the PI off and on again, which caused the monitor to come live and I could login.

Again, not really hassle, but it would have been better to be able to login without causing an abnormal shutdown.

So my question is, is this expected or is there a way to allow a monitor to be added once a Pi is already running?

Was the HDMI->DVI lead the problem?
Would it have worked if I'd connected a composite TV?
Is the HDMI display checked at startup, and disabled if it is not present and if so is there a way to override this?

Cheers for any advice anyone can suggest.

DAve
Pi count: 2 (raspbmc | tinker pi)
Games developer by day : Linux newbie by night

PS1981
Posts: 445
Joined: Wed Dec 12, 2012 4:11 pm

Re: Connecting a DVI monitor via HDMI after boot.

Mon Apr 08, 2013 12:50 pm

I think, when booting that if hdmi is not detected, the pi diverts to the analogue output. Correct me if I'm wrong though.

User avatar
rpdom
Posts: 16386
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Connecting a DVI monitor via HDMI after boot.

Mon Apr 08, 2013 3:27 pm

PS1981 wrote:I think, when booting that if hdmi is not detected, the pi diverts to the analogue output. Correct me if I'm wrong though.
That is correct - unless you set "hdmi_force_hotplug=1" in /boot/config.txt, which will force the Pi to use HDMI even if no active monitor is connected to it, or "hdmi_ignore_hotplug=1", which forces the Pi to use composite output even if an HDMI monitor is connected.

I think it is possible to switch outputs using the tvservice command and fbset a couple of times, but I haven't tried that yet.

Return to “General discussion”