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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?

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I have a HDMI to DVI cable that I've yet to test. I hope it works. –  Jivings Jun 13 '12 at 14:37
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I remember reading somewhere on Wiki that passive HDMI-DVI adapters should work but HDMI-VGA requires an active converter. –  Tibor Jun 13 '12 at 14:51
    
Would a composite-VGA be a better option? –  Alex Chamberlain Jun 13 '12 at 15:48
    
I think the product you linked to is designed to connect a PC's VGA output to a monitor's HDMI input, i.e. the opposite direction to what you want. –  finnw Jun 13 '12 at 16:01
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@Jivings - That's odd, HDMI is just single link DVI-D with a different connector. Are you sure it's not your monitor failing to sync to the resolution used by your RPi? –  Mark Booth Jun 14 '12 at 10:15
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7 Answers

up vote 48 down vote accepted

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

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Good answer, want to select it. One small bit: what is an HDMI to VGA cable and why will it not work with the Raspberry Pi? –  AlanSE Jun 13 '12 at 15:50
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@AlanSE, dedicated HDMI to VGA cables will work, as they contain the necessary circuitry. But I assumed that was not what you meant because you said "simple cable." –  finnw Jun 13 '12 at 15:51
    
What I meant is a simple cable like the one I linked to in the question. This cable does not contain the necessary circuitry. It works for some graphics cards and people are going to keep being confused about it unless it's clear what makes those different and why that does not apply for the Raspberry Pi. –  AlanSE Jun 13 '12 at 15:54
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@AlanSE - The important thing about that Amazon item is the NOTE: Your Video card must support digital signal output through VGA port function. I don't know of any video cards which support outputting VGA over pins of a HDMI connector, and a quick google search couldn't find any. –  Mark Booth Jun 14 '12 at 10:21
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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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You write that it needs some tuning? Does it need that in order to work at all, or does it need the tuning just to get a better picture? I am trying to connect my laptop/Raspberry to a monitor with a similar active adapter, and there is simply no connection. –  Mads Skjern Feb 11 at 21:09
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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 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)

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What type of DVI input did you have (like DVI-D) and was it a single link or dual link cable? I have an HP monitor myself and will need to get a cable for it. Is the selection based entirely on the monitor, or does the RasPi HDMI specs have anything to do with it? –  AlanSE Jun 13 '12 at 20:00
    
@AlanSE The DVI adapter was a DVI-I, and the monitor wanted a DVI-D. The specs for the pi had nothing to do with it simple problem of pin/connector geometry. The cable I linked to in my answer works like a charm and was far cheaper than most local alternatives even with the expedited shipping included. –  Steve Robillard Jun 13 '12 at 20:09
    
I still don't understand something. Why would you get a DVI-I adapter? And since the cable to your DVI monitor should have a male connector, and since the DVI-I has more connections than the DVI-D, you shouldn't physically be able to plug it in. The Amazon link you give isn't clear in the description, but the picture looks like DVI-D. This discussion might be better suited for a DVI question, but I'll see about giving an update when I do this myself. –  AlanSE Jun 14 '12 at 15:59
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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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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.

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Why is this downvoted? –  Bryan Dunsmore Jun 13 '12 at 15:19
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probably because it will not work. The OP is (if I understand correctly) asking about a combination of a HDMI->DVI cable and DVI->VGA adapter. Your solution will work only for a DVI monitor. –  finnw Jun 13 '12 at 15:42
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I had in mind more of HDMI->VGA as opposed to HDMI->DVI->VGA although that's not important. Your claim that it can use a DVI monitor with passive cables is useful and relevant to the question, as well as the claim that it can not work with a VGA monitor without conversion equipment. I think we are close to consensus on that. –  AlanSE Jun 13 '12 at 15:48
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Here's a quick tutorial explaining exactly how to enable VGA output via a $5 cable I brought.

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Hi Can you please write a brief description on how to do this. Linking to an external link is not great. –  ppumkin Dec 7 '12 at 9:28
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This should work, it definitely does for HDMI to DVI. I had my raspberry pi set up (until I got kernel panic from keyboard) yesterday using a HDMI lead with a DVI converter.

I have just remembered a step that I had to do to get it working. In the config.txt file on the SD card is a line that says something like HDMI = 17, I removed the line (in fact I deleted the file), which caused it to work.

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HDMI to VGA can't work with a simple cable for the reasons stated by finnw –  Martin Thompson Jun 13 '12 at 20:15
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