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One may buy a simple HDMI-to-VGA cable, or an HDMI-to-DVI cable. Example: on Amazon. However, my vague knowledge is that these cables only work for video cards that have special support for this function. Does the Raspberry Pi support such things?

Is there any easy way to use the Raspberry Pi on a screen that only takes VGA input without a converter box? What kind of conversion to other video outputs would the Raspberry Pi hardware support, and what cables or other equipment would be necessary for this?

Peter Mortensen
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AlanSE
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7 Answers7

81

No.

The reason a DVI-to-VGA adapter works on your PC & laptop is that DVI includes analog (RGB) pins. The adapter is passive; It just connects the red analog output of the PC to the red analog input of the monitor, ditto for green and blue. They are included on most PCs and laptops for backward compatibility.

HDMI-to-DVI cables are also passive, but they carry digital signals only. The analog RGB signals are missing, but that does not matter as the DVI monitor does not need them.

HDMI contains no analog signal so it is not possible for any combination of passive adapters and/or cables to convert it to VGA.

Active adapters work because they use DSPs and DACs to convert from one standard to the other, but of course they are more expensive than passive cables.

Related forum thread: http://www.raspberrypi.org/phpBB3/viewtopic.php?f=30&t=8125

finnw
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The Neewer HDMI to VGA converter lead from Amazon does indeed work with the RPi but as has been reported elsewhere you have to do a bit of fine tuning in the /boot/config.txt file.

I still cannot get my Samsung 943N to see anything but a simple Dell generic 15" VGA monitor works fine. One problem seems to be that the default output signal level is not sufficient so setting config_hdmi_boost=4 seems necessary. The monitor also complains that it wants 1024x768 at 60Hz which is hdmi_mode=16.

The article at http://elinux.org/RPi_config.txt also suggests that the hdmi_group values documented should be 0 and 1 not 1 and 2 and indeed I needed to change hdmi_group to 1. So my current file looks like:

hdmi_drive=2 
config_hdmi_boost=4 
hdmi_group=1 
hdmi_mode=16 
hdmi_force_hotplug=1 
disable_overscan=0

Modification for Dell 15" Monitor with Debian GNU/Linux 6.0 OS I found that it would only work with: hdmi_group=2

Raspberry Pi User Guide by Eben Upton has the video modes in the appendix. The user guide lists the hdmi_group values as 1 or 2.

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Muonman
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The "simple" HDMI to VGA cables will not work quite simply because HDMI signals are pure digital and VGA is analogue. I made the mistake of buying a very cheap cable from Amazon which did not work for reasons that are clear to me now. I am awaiting the delivery of a "Neewer Black HDMI Input To VGA Adapter Converter For PC Laptop" from Amazon which I am confident will do the job. It was less than £15. I will post my findings here.

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Muonman
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I am using this cable to connect my Raspberry Pi to an HP monitor (with DVI input).

A couple of notes: You can not then connect another cable or adapter to change this to a VGA input. Secondly, if converting the Raspberry Pi's HDMI to DVI be careful of the DVI connector; there is more than one type and one size does not fit all (I learned this lesson the hard way).

Peter Mortensen
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Steve Robillard
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1

It may be a problem with your configuration file. Try deleting it, and if that doesn't work try changing it to this.

# config.txt
hdmi_group = 2
hdmi_mode  = 4

A list of available properties for the Raspberry Pi can be found here.

1

It is important to not just give up when the adaptor/converter doesn't seem to work out of the box. Most probably there will be converters which won't work and VGA displays which won't be supported, but my feeling is most of them work just fine - with some extra steps.

If you want to check whether yours has chances, use an empty /boot/config.txt file and add hdmi_safe=1 to it.

While this won't give you the best resolution, it probably will get you to the login prompt.

After that you can start with tweaking it further until you get the most out of your monitor capabilities.

You can get some useful information about your monitor by entering these 3 commands:

/opt/vc/bin/tvservice -m CEA /opt/vc/bin/tvservice -m DMT /opt/vc/bin/tvservice -s

Use the Raspberry Pi Video Modes reference link to yield the above results and finetune.

After rebooting the Pi, your monitor firmware might show errors like 'out of sync' or 'resolution not supported'. Lower the resolution and/or refresh rate and try again.

After testing I got good results even with small Chinese $3 adaptors connected to the cheapest monitors available in the shop. Out of the box the converter gave a blank screen with the monitor going into powersave mode seconds after. After following the above steps my /boot/config.txt now shows:

hdmi_group=1 hdmi_mode=16

EDP
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No +5v supply from setop box like tatasky dishtv hd box in hdmi output so converter not work. it can work properly after supply +5v in pin no.2of hdmi port.

Gererin
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