HDMI 'No Signal' With No Config - Wrong Format With Config


5 posts
by nimdy » Thu Apr 19, 2012 1:25 pm
Hi Guys,

I've been able to play with my Pi, but I'm having issues with the display. On a freshly written Debian SD I get 'No Signal' on the display. On my first boot I thought (great, just my luck, ive got a dud!) but I troubleshooted a little and found that it was operational (plug in the Cat5, find the device from the router and SSH into it).

I've read some of the HDMI issues threads on the forum, and have got something on the display. I've used the following in the confix.txt:

hdmi_force_hotplug=1

hdmi_mode=16

This gives me a picture but a border around all for sides of the screen. I'm also not sure if the colour / refresh rate is correct for my LCD TV.

I've tried other hdmi_modes, with varying picture sizes and positions. Each time I've rebooted to see the effects (I assume this is the correct way).

My display is an LG M228WD LCD TV. I know that when I connect a PC to it via VGA/D-SUB I have to choose a non-standard resoloution to make it work (something like 1366 width rather than standard 1360, I think). Would this also apply to the HDMI side? I thought if it is an HD tv, it should manage 720/1080 resoloutions.

Any help or advise will be greatly appreciated. :)
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by Simon H » Thu Apr 19, 2012 2:45 pm
I was just going to reply in the other thread when I saw you had created a new one.

You can add the parameters

overscan_left=-30

overscan_right=-30

overscan_top=-30

overscan_bottom=-30

-30 is an example I used,+ values increases the borders – values reduce the borders (stretch the screen).

The problem is probably the resolution doesn"t match the monitor though, if you look in the other thread

http://www.raspberrypi.org/for.....mposite-ok

Dom posted some different parameters to try and there is a link to a list of resolutions under a config.txt post.
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Joined: Sun Jan 08, 2012 2:41 pm
by Simon H » Thu Apr 19, 2012 2:51 pm
Also look under the ./tvservice commands in that thread, you can get the current resolution and the available ones for your monitor. I found that very usefull.

I am currently having trouble with getting it to drive my monitor up to the full 1080p it is capable of but I will start another thread on that when I get home later.
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by dom » Thu Apr 19, 2012 4:21 pm
If your monitor is misbehaving dump the edid data, and we can investigate.

You will need a new tvservice for this to work. There's a link and info here:

https://github.com/raspberrypi/firmware/issues/4

(and try the latest firmware from github: https://github.com/raspberrypi/firmware there's been some tweaks over last few days)
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Location: Cambridge
by nimdy » Thu Apr 19, 2012 6:25 pm
Hi all,

I've downloaded the new version of tvservice from git and done a dump. Hopefully you can retrieve it from this link: http://dl.dropbox.com/u/5170394/edid.dat

The other commands you mentioned in post 9 (of the other thread) just return 'Group CEA has 0 modes:' 'Group DMT has 0 modes:'

From what I am reading, these commands are supposed to interegate the display for what modes it supports, right? If this is the case, is my cheap LG TV at fault?

[edit]

Oh and I've had a look at that dumped file. It shows a line of symbols and the model number of my TV (M228WD-BZ)

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