Can't run Raspberry pi using dvi/hdmi adapter

[melholt]

can anyone please help? I am trying to set up some Raspberry pi on an RM CC4 network using dvi/hdmi adapters as space is limited. The dvi/vga switch on the side of the monitor is not allowing me to switch between the 2 on some of the machines. On some of them it will work then it won't, reverting to the VGA display after a few seconds. I have tried changing the HDMI cables and switching adapters and trying a different Pi.

 

Can anyone please advise? I have a year 6 code club after school who are looking forward to using the Pi and will be disappointed.

Any advice gratefully received

 

Mel

[LosOjos]

Hold Shift while booting the Pi to bring up recovery, then look for the "config.txt. option in the drop down menu (sorry, this is from memory)

 

The text file that opens up is a config file that runs at boot. Scroll down until you see hdmi_safe_mode (or similar, the file is commented) and enable it. Save and reboot.

 

If that works, you can then experiment with setting the resolution yourself in that same file (accessible via /boot/config.txt when running Raspbian) until you find a reliable one at decent resolution. I had to do this with a class load of them myself using HDMI/DVI adapters.

 

Good luck!

[melholt]

Many thanks for the response, but it doesn't get as far in as letting me see the Pi booting up. It refuses to switch between VGA and DVI it simply reverts to VGA and the RM logon screen. Have tried switching everything around but the issue appears to be intermittent. i can login using a Pi on one machine, shut it down and it won't work on another PC. Similarly a PC can work for 1 Pi and not the next one I connect to the same PC.

Hope that makes sense!

Mel

[LosOjos]

Many thanks for the response, but it doesn't get as far in as letting me see the Pi booting up. It refuses to switch between VGA and DVI it simply reverts to VGA and the RM logon screen. Have tried switching everything around but the issue appears to be intermittent. i can login using a Pi on one machine, shut it down and it won't work on another PC. Similarly a PC can work for 1 Pi and not the next one I connect to the same PC.

Hope that makes sense!

Mel

 

If I'm understanding correctly, you have a PC and the Pi connected to the same monitor, but the monitor won't let you switch between the two - correct?

 

Does the Pi function properly if you unplug the PC from the monitor?

 

If so, there may be nothing you can do but unplug the PCs from the monitor when you want to use the Pis I'm afraid. Have a dig through the monitor's settings for anything hinting at a preferred connection or automatic signal detection, but you're probably out of luck; some monitors just don't handle multiple sources well unfortunately and will switch to a source once they detect a signal, not necessarily the source you want!

[MrBrownPr]

The file mentioned, config.txt, can be edited on another computer. The SD card will have a (small) FAT32 partition that contains config.txt and some other files to boot the Pi. If you take out the SD card and stick it in another computer you should be able to edit config.txt and set hdmi_safe=1.

 

If that works then you can play around with other settings in config.txt. I think what you might actually need is hdmi_force_hotplug=1. You can read more about config.txt here:

 

RPiconfig - eLinux.org